Science.gov

Sample records for gprc5a tumor suppressor

  1. GPRC5A is a potential oncogene in pancreatic ductal adenocarcinoma cells that is upregulated by gemcitabine with help from HuR

    PubMed Central

    Zhou, H; Telonis, A G; Jing, Y; Xia, N L; Biederman, L; Jimbo, M; Blanco, F; Londin, E; Brody, J R; Rigoutsos, I

    2016-01-01

    GPRC5A is an orphan G-protein coupled receptor with an intriguing dual behavior, acting as an oncogene in some cancers and as a tumor suppressor in other cancers. In the pancreatic cancer context, very little is known about GPRC5A. By analyzing messenger RNA (mRNA) expression data from 675 human cancer cell lines and 10 609 samples from The Cancer Genome Atlas (TCGA) we found that GPRC5A's abundance in pancreatic cancer is highest (cell lines) or second highest (TCGA) among all tissues and cancer types. Further analyses of an independent set of 252 pancreatic normal and cancer samples showed GPRC5A mRNA to be more than twofold upregulated in primary tumor samples compared with normal pancreas (P-value<10−5), and even further upregulated in pancreatic cancer metastases to various organs (P-value=0.0021). Immunostaining of 208 cores (103 samples) of a tissue microarray showed generally low expression of GPRC5A protein in normal pancreatic ductal cells; on the other hand, in primary and metastatic samples, GPRC5A protein levels were dramatically increased in pancreatic ductal cells. In vitro studies of multiple pancreatic cancer cell lines showed that an increase in GPRC5A protein levels promoted pancreatic cancer cell growth and migration. Unexpectedly, when we treated pancreatic cancer cell lines with gemcitabine (2′,2′-difluorodeoxycytidine), we observed an increase in GPRC5A protein abundance. On the other hand, when we knocked down GPRC5A we sensitized pancreatic cancer cells to gemcitabine. Through further experimentation we showed that the monotonic increase in GPRC5A protein levels that we observe for the first 18 h following gemcitabine treatment results from interactions between GPRC5A's mRNA and the RNA-binding protein HuR, which is an established key mediator of gemcitabine's efficacy in cancer cells. As we discovered, the interaction between GPRC5A and HuR is mediated by at least one HuR-binding site in GPRC5A's mRNA. Our findings indicate that

  2. High prevalence of GPRC5A germline mutations in BRCA1-mutant breast cancer patients.

    PubMed

    Sokolenko, Anna P; Bulanova, Daria R; Iyevleva, Aglaya G; Aleksakhina, Svetlana N; Preobrazhenskaya, Elena V; Ivantsov, Alexandr O; Kuligina, Ekatherina Sh; Mitiushkina, Natalia V; Suspitsin, Evgeny N; Yanus, Grigoriy A; Zaitseva, Olga A; Yatsuk, Olga S; Togo, Alexandr V; Kota, Poojitha; Dixon, J Michael; Larionov, Alexey A; Kuznetsov, Sergey G; Imyanitov, Evgeny N

    2014-05-15

    In a search for new breast cancer (BC) predisposing genes, we performed a whole exome sequencing analysis using six patient samples of familial BC and identified a germline inactivating mutation c.183delG [p. Arg61fs] in an orphan G protein-coupled receptor GPRC5A. An extended case-control study revealed a tenfold enrichment for this mutation in BC patients carrying the 5382insC allele of BRCA1, the major founder mutation in the Russian population, compared to wild-type BRCA1 BC cases [6/117 (5.1%) vs. 8/1578 (0.5%), p = 0.0002]. In mammary tumors (n = 60), the mRNA expression of GPRC5A significantly correlated with that of BRCA1 (p = 0.00018). In addition, the amount of GPRC5A transcript was significantly lower in BC obtained from BRCA1 mutation carriers (n = 17) compared to noncarriers (n = 93) (p = 0.026). Accordingly, a siRNA-mediated knockdown of either BRCA1 or GPRC5A in the MDA-MB-231 human BC cell line reduced expression of GPRC5A or BRCA1, respectively. Knockdown of GPRC5A also attenuated radiation-induced BRCA1- and RAD51-containing nuclear DNA repair foci. Taken together, these data suggest that GPRC5A is a modifier of BC risk in BRCA1 mutation carriers and reveals a functional interaction of these genes.

  3. GPRC5A suppresses protein synthesis at the endoplasmic reticulum to prevent radiation-induced lung tumorigenesis

    PubMed Central

    Wang, Jian; Farris, Alton B.; Xu, Kaiming; Wang, Ping; Zhang, Xiangming; Duong, Duc M.; Yi, Hong; Shu, Hui-Kuo; Sun, Shi-Yong; Wang, Ya

    2016-01-01

    GPRC5A functions as a lung tumour suppressor to prevent spontaneous and environmentally induced lung carcinogenesis; however, the underlying mechanism remains unclear. Here we reveal that GPRC5A at the endoplasmic reticulum (ER) membrane suppresses synthesis of the secreted or membrane-bound proteins including a number of oncogenes, the most important one being Egfr. The ER-located GPRC5A disturbs the assembly of the eIF4F-mediated translation initiation complex on the mRNA cap through directly binding to the eIF4F complex with its two middle extracellular loops. Particularly, suppression of EGFR by GPRC5A contributes significantly to preventing ionizing radiation (IR)-induced lung tumorigenesis. Thus, GPRC5A deletion enhances IR-promoted EGFR expression through an increased translation rate, thereby significantly increasing lung tumour incidence in Gprc5a−/− mice. Our findings indicate that under-expressed GPRC5A during lung tumorigenesis enhances any transcriptional stimulation through an active translational status, which can be used to control oncogene expression and potentially the resulting related disease. PMID:27273304

  4. Tumor suppressors: enhancers or suppressors of regeneration?

    PubMed Central

    Pomerantz, Jason H.; Blau, Helen M.

    2013-01-01

    Tumor suppressors are so named because cancers occur in their absence, but these genes also have important functions in development, metabolism and tissue homeostasis. Here, we discuss known and potential functions of tumor suppressor genes during tissue regeneration, focusing on the evolutionarily conserved tumor suppressors pRb1, p53, Pten and Hippo. We propose that their activity is essential for tissue regeneration. This is in contrast to suggestions that tumor suppression is a trade-off for regenerative capacity. We also hypothesize that certain aspects of tumor suppressor pathways inhibit regenerative processes in mammals, and that transient targeted modification of these pathways could be fruitfully exploited to enhance processes that are important to regenerative medicine. PMID:23715544

  5. Orphan G protein-coupled receptor GPRC5A modulates integrin β1-mediated epithelial cell adhesion.

    PubMed

    Bulanova, Daria R; Akimov, Yevhen A; Rokka, Anne; Laajala, Teemu D; Aittokallio, Tero; Kouvonen, Petri; Pellinen, Teijo; Kuznetsov, Sergey G

    2016-10-07

    G-Protein Coupled Receptor (GPCR), Class C, Group 5, Member A (GPRC5A) has been implicated in several malignancies. The underlying mechanisms, however, remain poorly understood. Using a panel of human cell lines, we demonstrate that CRISPR/Cas9-mediated knockout and RNAi-mediated depletion of GPRC5A impairs cell adhesion to integrin substrates: collagens I and IV, fibronectin, as well as to extracellular matrix proteins derived from the Engelbreth-Holm-Swarm (EHS) mouse sarcoma (Matrigel). Consistent with the phenotype, knock-out of GPRC5A correlated with a reduced integrin β1 (ITGB1) protein expression, impaired phosphorylation of the focal adhesion kinase (FAK), and lower activity of small GTPases RhoA and Rac1. Furthermore, we provide the first evidence for a direct interaction between GPRC5A and a receptor tyrosine kinase EphA2, an upstream regulator of FAK, although its contribution to the observed adhesion phenotype is unclear. Our findings reveal an unprecedented role for GPRC5A in regulation of the ITGB1-mediated cell adhesion and it's downstream signaling, thus indicating a potential novel role for GPRC5A in human epithelial cancers.

  6. Single-cell Sequencing Reveals Variants in ARID1A, GPRC5A and MLL2 Driving Self-renewal of Human Bladder Cancer Stem Cells.

    PubMed

    Yang, Zhao; Li, Chong; Fan, Zusen; Liu, Hongjie; Zhang, Xiaolong; Cai, Zhiming; Xu, Liqin; Luo, Jian; Huang, Yi; He, Luyun; Liu, Chunxiao; Wu, Song

    2017-01-01

    Cancer stem cells are considered responsible for many important aspects of tumors such as their self-renewal, tumor-initiating, drug-resistance and metastasis. However, the genetic basis and origination of human bladder cancer stem cells (BCSCs) remains unknown. Here, we conducted single-cell sequencing on 59 cells including BCSCs, bladder cancer non-stem cells (BCNSCs), bladder epithelial stem cells (BESCs) and bladder epithelial non-stem cells (BENSCs) from three bladder cancer (BC) specimens. Specifically, BCSCs demonstrate clonal homogeneity and suggest their origin from BESCs or BCNSCs through phylogenetic analysis. Moreover, 21 key altered genes were identified in BCSCs including six genes not previously described in BC (ETS1, GPRC5A, MKL1, PAWR, PITX2 and RGS9BP). Co-mutations of ARID1A, GPRC5A and MLL2 introduced by CRISPR/Cas9 significantly enhance the capabilities of self-renewal and tumor-initiating of BCNSCs. To our knowledge, our study first provides an overview of the genetic basis of human BCSCs with single-cell sequencing and demonstrates the biclonal origin of human BCSCs via evolution analysis.

  7. Is PML a Tumor Suppressor?

    PubMed Central

    Mazza, Massimiliano; Pelicci, Pier Giuseppe

    2013-01-01

    The role of the promyelocytic leukemia (PML) protein has been widely tested in many different contexts, as attested by the hundreds of papers present in the literature. In most of these studies, PML is regarded as a tumor suppressor, a notion on the whole accepted by the scientific community. In this review, we examine how the concept of tumor-suppressor gene has evolved until now and then systematically assess whether this assumption for PML is supported by unambiguous experimental evidence. PMID:23847764

  8. Tumor suppressor molecules and methods of use

    DOEpatents

    Welch, Peter J.; Barber, Jack R.

    2004-09-07

    The invention provides substantially pure tumor suppressor nucleic acid molecules and tumor suppressor polypeptides. The invention also provides hairpin ribozymes and antibodies selective for these tumor suppressor molecules. Also provided are methods of detecting a neoplastic cell in a sample using detectable agents specific for the tumor suppressor nucleic acids and polypeptides.

  9. WWOX: A fragile tumor suppressor

    PubMed Central

    Schrock, Morgan S

    2015-01-01

    WWOX, the WW domain-containing oxidoreductase gene at chromosome region 16q23.3–q24.1, spanning chromosomal fragile site FRA16D, encodes the 46 kDa Wwox protein, a tumor suppressor that is lost or reduced in expression in a wide variety of cancers, including breast, prostate, ovarian, and lung. The function of Wwox as a tumor suppressor implies that it serves a function in the prevention of carcinogenesis. Indeed, in vitro studies show that Wwox protein interacts with many binding partners to regulate cellular apoptosis, proliferation, and/or maturation. It has been reported that newborn Wwox knockout mice exhibit nascent osteosarcomas while Wwox+/− mice exhibit increased incidence of spontaneous and induced tumors. Furthermore, absence or reduction of Wwox expression in mouse xenograft models results in increased tumorigenesis, which can be rescued by Wwox re-expression, though there is not universal agreement among investigators regarding the role of Wwox loss in these experimental models. Despite this proposed tumor suppressor function, the overlap of the human WWOX locus with FRA16D sensitizes the gene to protein-inactivating deletions caused by replication stress. The high frequency of deletions within the WWOX locus in cancers of various types, without the hallmark protein inactivation-associated mutations of “classical” tumor suppressors, has led to the proposal that WWOX deletions in cancers are passenger events that occur in early cancer progenitor cells due to fragility of the genetic locus, rather than driver events which provide the cancer cell a selective advantage. Recently, a proposed epigenetic cause of chromosomal fragility has suggested a novel mechanism for early fragile site instability and has implications regarding the involvement of tumor suppressor genes at chromosomal fragile sites in cancer. In this review, we provide an overview of the evidence for WWOX as a tumor suppressor gene and put this into the context of fragility

  10. Tumor suppressor ARF

    PubMed Central

    Través, Paqui G.; Luque, Alfonso; Hortelano, Sonsoles

    2012-01-01

    ARF (alternative reading frame) is one of the most important tumor regulator playing critical roles in controlling tumor initiation and progression. Recently, we have demonstrated a novel and unexpected role for ARF as modulator of inflammatory responses. PMID:23162766

  11. Therapeutic targeting of tumor suppressor genes.

    PubMed

    Morris, Luc G T; Chan, Timothy A

    2015-05-01

    Carcinogenesis is a multistep process attributable to both gain-of-function mutations in oncogenes and loss-of-function mutations in tumor suppressor genes. Currently, most molecular targeted therapies are inhibitors of oncogenes, because inactivated tumor suppressor genes have proven harder to "drug." Nevertheless, in cancers, tumor suppressor genes undergo alteration more frequently than do oncogenes. In recent years, several promising strategies directed at tumor suppressor genes, or the pathways controlled by these genes, have emerged. Here, we describe advances in a number of different methodologies aimed at therapeutically targeting tumors driven by inactivated tumor suppressor genes.

  12. Discovery of Tumor Suppressor Gene Function.

    ERIC Educational Resources Information Center

    Oppenheimer, Steven B.

    1995-01-01

    This is an update of a 1991 review on tumor suppressor genes written at a time when understanding of how the genes work was limited. A recent major breakthrough in the understanding of the function of tumor suppressor genes is discussed. (LZ)

  13. Targeting tumor suppressor networks for cancer therapeutics.

    PubMed

    Guo, Xuning Emily; Ngo, Bryan; Modrek, Aram Sandaldjian; Lee, Wen-Hwa

    2014-01-01

    Cancer is a consequence of mutations in genes that control cell proliferation, differentiation and cellular homeostasis. These genes are classified into two categories: oncogenes and tumor suppressor genes. Together, overexpression of oncogenes and loss of tumor suppressors are the dominant driving forces for tumorigenesis. Hence, targeting oncogenes and tumor suppressors hold tremendous therapeutic potential for cancer treatment. In the last decade, the predominant cancer drug discovery strategy has relied on a traditional reductionist approach of dissecting molecular signaling pathways and designing inhibitors for the selected oncogenic targets. Remarkable therapies have been developed using this approach; however, targeting oncogenes is only part of the picture. Our understanding of the importance of tumor suppressors in preventing tumorigenesis has also advanced significantly and provides a new therapeutic window of opportunity. Given that tumor suppressors are frequently mutated, deleted, or silenced with loss-of-function, restoring their normal functions to treat cancer holds tremendous therapeutic potential. With the rapid expansion in our knowledge of cancer over the last several decades, developing effective anticancer regimens against tumor suppressor pathways has never been more promising. In this article, we will review the concept of tumor suppression, and outline the major therapeutic strategies and challenges of targeting tumor suppressor networks for cancer therapeutics.

  14. Tumor suppressor identified as inhibitor of inflammation

    Cancer.gov

    Scientists at NCI have found that a protein, FBXW7, which acts as a tumor suppressor, is also important for the reduction in strength of inflammatory pathways. It has long been recognized that a complex interaction exists between cancer causing mechanisms

  15. Targeting tumor suppressor genes for cancer therapy.

    PubMed

    Liu, Yunhua; Hu, Xiaoxiao; Han, Cecil; Wang, Liana; Zhang, Xinna; He, Xiaoming; Lu, Xiongbin

    2015-12-01

    Cancer drugs are broadly classified into two categories: cytotoxic chemotherapies and targeted therapies that specifically modulate the activity of one or more proteins involved in cancer. Major advances have been achieved in targeted cancer therapies in the past few decades, which is ascribed to the increasing understanding of molecular mechanisms for cancer initiation and progression. Consequently, monoclonal antibodies and small molecules have been developed to interfere with a specific molecular oncogenic target. Targeting gain-of-function mutations, in general, has been productive. However, it has been a major challenge to use standard pharmacologic approaches to target loss-of-function mutations of tumor suppressor genes. Novel approaches, including synthetic lethality and collateral vulnerability screens, are now being developed to target gene defects in p53, PTEN, and BRCA1/2. Here, we review and summarize the recent findings in cancer genomics, drug development, and molecular cancer biology, which show promise in targeting tumor suppressors in cancer therapeutics.

  16. Modulation and Expression of Tumor Suppressor Genes by Environmental Agents.

    DTIC Science & Technology

    1996-12-01

    MAMA produced other tumors in medaka (e.g. liver) and Rb expression is altered in many human tumors , the capability of examining the pathology of all...AD GRANT NUMBER DAMDI7-93-J-3011 TITLE: Modulation and Expression of Tumor Suppressor Genes by Environmental Agents PRINCIPAL INVESTIGATOR: Gary K...SUBTITLE 5. FUNDING NUMBERS Modulation and Expression of Tumor Suppressor Genes by Environmental Agents DAMDl7-93- J-3011 6. AUTHOR(S) Gary K

  17. The tumor suppressor CDKN3 controls mitosis.

    PubMed

    Nalepa, Grzegorz; Barnholtz-Sloan, Jill; Enzor, Rikki; Dey, Dilip; He, Ying; Gehlhausen, Jeff R; Lehmann, Amalia S; Park, Su-Jung; Yang, Yanzhu; Yang, Xianlin; Chen, Shi; Guan, Xiaowei; Chen, Yanwen; Renbarger, Jamie; Yang, Feng-Chun; Parada, Luis F; Clapp, Wade

    2013-06-24

    Mitosis is controlled by a network of kinases and phosphatases. We screened a library of small interfering RNAs against a genome-wide set of phosphatases to comprehensively evaluate the role of human phosphatases in mitosis. We found four candidate spindle checkpoint phosphatases, including the tumor suppressor CDKN3. We show that CDKN3 is essential for normal mitosis and G1/S transition. We demonstrate that subcellular localization of CDKN3 changes throughout the cell cycle. We show that CDKN3 dephosphorylates threonine-161 of CDC2 during mitotic exit and we visualize CDC2(pThr-161) at kinetochores and centrosomes in early mitosis. We performed a phosphokinome-wide mass spectrometry screen to find effectors of the CDKN3-CDC2 signaling axis. We found that one of the identified downstream phosphotargets, CKβ phosphorylated at serine 209, localizes to mitotic centrosomes and controls the spindle checkpoint. Finally, we show that CDKN3 protein is down-regulated in brain tumors. Our findings indicate that CDKN3 controls mitosis through the CDC2 signaling axis. These results have implications for targeted anticancer therapeutics.

  18. Studies of Tumor Suppressor Genes via Chromosome Engineering.

    PubMed

    Kugoh, Hiroyuki; Ohira, Takahito; Oshimura, Mitsuo

    2015-12-30

    The development and progression of malignant tumors likely result from consecutive accumulation of genetic alterations, including dysfunctional tumor suppressor genes. However, the signaling mechanisms that underlie the development of tumors have not yet been completely elucidated. Discovery of novel tumor-related genes plays a crucial role in our understanding of the development and progression of malignant tumors. Chromosome engineering technology based on microcell-mediated chromosome transfer (MMCT) is an effective approach for identification of tumor suppressor genes. The studies have revealed at least five tumor suppression effects. The discovery of novel tumor suppressor genes provide greater understanding of the complex signaling pathways that underlie the development and progression of malignant tumors. These advances are being exploited to develop targeted drugs and new biological therapies for cancer.

  19. Tumor suppressor activity of RIG-I

    PubMed Central

    Li, Xian-Yang; Guo, He-Zhou; Zhu, Jiang

    2014-01-01

    Retinoic acid inducible gene-I (RIG-I), named for the observation that its mRNA expression is highly upregulated in the progression of all-trans retinoic acid (ATRA)-induced maturation of acute promyelocytic leukemia (APL) cells, has been well documented as a pivotal virus-associated molecular pattern recognition receptor (PRR) responsible for triggering innate immunity. Upon recognizing viral RNA ligands, RIG-I experiences a series of programmed conformational changes and modifications that unleash its activity through the formation of complexes with various binding partners. Such partners include the mitochondria membrane-anchored protein IPS-1 (also named MAVS/VISA/Cardif) that activates both the IRF3/7 and NF-κB pathways. These partnerships and resulting pathway activations underlie the synthesis of type I interferon and other inflammatory factors. Recent studies have demonstrated that RIG-I is also involved in the regulation of basic cellular processes outside of innate immunity against viral infections, such as hematopoietic proliferation and differentiation, maintenance of leukemic stemness, and tumorigenesis of hepatocellular carcinoma. In this review, we will highlight recent studies leading up to the recognition that RIG-I performs an essential function as a tumor suppressor and try to reconcile this activity of RIG-I with its well-known role in protecting cells against viral infection. PMID:27308362

  20. Tumor suppressor genes in familial adenomatous polyposis

    PubMed Central

    Eshghifar, Nahal; Farrokhi, Naser; Naji, Tahereh; Zali, Mohammadreza

    2017-01-01

    Colorectal cancer (CRC) is mostly due to a series of genetic alterations that are being greatly under the influence of the environmental factors. These changes, mutational or epigenetic modifications at transcriptional forefront and/or post-transcriptional effects via miRNAs, include inactivation and the conversion of proto-oncogene to oncogenes, and/or inactivation of tumor suppressor genes (TSG). Here, a thorough review was carried out on the role of TSGs with the focus on the APC as the master regulator, mutated genes and mal-/dysfunctional pathways that lead to one type of hereditary form of the CRC; namely familial adenomatous polyposis (FAP). This review provides a venue towards defining candidate genes that can be used as new PCR-based markers for early diagnosis of FAP. In addition to diagnosis, defining the modes of genetic alterations will open door towards genome editing to either suppress the disease or reduce its progression during the course of action. PMID:28331559

  1. Tumor Suppressors Status in Cancer Cell Line Encyclopedia

    PubMed Central

    Sonkin, Dmitriy; Hassan, Mehedi; Murphy, Denis J.; Tatarinova, Tatiana V.

    2013-01-01

    Tumor suppressors play a major role in the etiology of human cancer, and typically achieve a tumor promoting effect upon complete functional inactivation. Bi-allelic inactivation of tumor suppressors may occur through genetic mechanisms (such as loss-of-function mutation, copy number (CN) loss, or loss-of-heterozygosity (LOH)), epigenetic mechanisms (such as promoter methylation or histone modification), or a combination of the two. We report systematically derived status of 69 known or putative tumor suppressors, across 799 samples of the Cancer Cell Line Encyclopedia. In order to generate such resource we constructed a novel comprehensive computational framework for the assessment of tumor suppressor functional “status”. This approach utilizes several orthogonal genomic data types, including mutation data, copy number, LOH and expression. Through correlation with additional data types (compound sensitivity and gene set activity) we show that this integrative method provides a more accurate assessment of tumor suppressor status than can be inferred by expression, copy number, or mutation alone. This approach has the potential for a more realistic assessment of tumor suppressor genes for both basic and translational oncology research. PMID:23639312

  2. Tumor suppressors status in cancer cell line Encyclopedia.

    PubMed

    Sonkin, Dmitriy; Hassan, Mehedi; Murphy, Denis J; Tatarinova, Tatiana V

    2013-08-01

    Tumor suppressors play a major role in the etiology of human cancer, and typically achieve a tumor-promoting effect upon complete functional inactivation. Bi-allelic inactivation of tumor suppressors may occur through genetic mechanisms (such as loss of function mutation, copy number (CN) loss, or loss of heterozygosity (LOH)), epigenetic mechanisms (such as promoter methylation or histone modification), or a combination of the two. We report systematically derived status of 69 known or putative tumor suppressors, across 799 samples of the Cancer Cell Line Encyclopedia. In order to generate such resource we constructed a novel comprehensive computational framework for the assessment of tumor suppressor functional "status". This approach utilizes several orthogonal genomic data types, including mutation data, copy number, LOH and expression. Through correlation with additional data types (compound sensitivity and gene set activity) we show that this integrative method provides a more accurate assessment of tumor suppressor status than can be inferred by expression, copy number, or mutation alone. This approach has the potential for a more realistic assessment of tumor suppressor genes for both basic and translational oncology research.

  3. Structure of the Wilms Tumor Suppressor

    SciTech Connect

    Stoll, R.; Lee, B.M.; Debler, E.W.; Laity, J.H.; Wilson, I.A.; Dyson, H.J.; Wright, P.E.

    2009-06-04

    The zinc finger domain of the Wilms tumor suppressor protein (WT1) contains four canonical Cys{sub 2}His{sub 2} zinc fingers. WT1 binds preferentially to DNA sequences that are closely related to the EGR-1 consensus site. We report the structure determination by both X-ray crystallography and NMR spectroscopy of the WT1 zinc finger domain in complex with DNA. The X-ray structure was determined for the complex with a cognate 14 base-pair oligonucleotide, and composite X-ray/NMR structures were determined for complexes with both the 14 base-pair and an extended 17 base-pair DNA. This combined approach allowed unambiguous determination of the position of the first zinc finger, which is influenced by lattice contacts in the crystal structure. The crystal structure shows the second, third and fourth zinc finger domains inserted deep into the major groove of the DNA where they make base-specific interactions. The DNA duplex is distorted in the vicinity of the first zinc finger, with a cytidine twisted and tilted out of the base stack to pack against finger 1 and the tip of finger 2. By contrast, the composite X-ray/NMR structures show that finger 1 continues to follow the major groove in the solution complexes. However, the orientation of the helix is non-canonical, and the fingertip and the N terminus of the helix project out of the major groove; as a consequence, the zinc finger side-chains that are commonly involved in base recognition make no contact with the DNA. We conclude that finger 1 helps to anchor WT1 to the DNA by amplifying the binding affinity although it does not contribute significantly to binding specificity. The structures provide molecular level insights into the potential consequences of mutations in zinc fingers 2 and 3 that are associated with Denys-Drash syndrome and nephritic syndrome. The mutations are of two types, and either destabilize the zinc finger structure or replace key base contact residues.

  4. [Interaction of two tumor suppressors: Phosphatase CTDSPL and Rb protein].

    PubMed

    Beniaminov, A D; Krasnov, G S; Dmitriev, A A; Puzanov, G A; Snopok, B A; Senchenko, V N; Kashuba, V I

    2016-01-01

    Earlier we established that CTDSPL gene encoding small carboxy-terminal domain serine phosphatase can be considered a classical tumor suppressor gene. Besides, transfection of tumor cell line MCF-7 with CTDSPL led to the content decrease of inactive phosphorylated form of another tumor suppressor, retinoblastoma protein (Rb), and subsequently to cell cycle arrest at the G1/S boundary. This result implied that small phosphatase CTDSPL is able to specifically dephosphorylate and activate Rb protein. In order to add some fuel to this hypothesis, in the present work we studied the interaction of two tumor suppressors CTDSPL and Rb in vitro. GST pool-down assay revealed that CTDSPL is able to precipitate Rb protein from MCF-7 cell extracts, while surface plasmon resonance technique showed that interaction of the two proteins is direct. Results of this study reassert that phosphatase CTDSPL and Rb could be involved in the common mechanism of cell cycle regulation.

  5. Targeted deletion of Wwox reveals a tumor suppressor function.

    PubMed

    Aqeilan, Rami I; Trapasso, Francesco; Hussain, Sadiq; Costinean, Stefan; Marshall, Dean; Pekarsky, Yuri; Hagan, John P; Zanesi, Nicola; Kaou, Mohamed; Stein, Gary S; Lian, Jane B; Croce, Carlo M

    2007-03-06

    The WW domain-containing oxidoreductase (WWOX) spans the second most common fragile site of the human genome, FRA16D, located at 16q23, and its expression is altered in several types of human cancer. We have previously shown that restoration of WWOX expression in cancer cells suppresses tumorigenicity. To investigate WWOX tumor suppressor function in vivo, we generated mice carrying a targeted deletion of the Wwox gene and monitored incidence of tumor formation. Osteosarcomas in juvenile Wwox(-/-) and lung papillary carcinoma in adult Wwox(+/-) mice occurred spontaneously. In addition, Wwox(+/-) mice develop significantly more ethyl nitrosourea-induced lung tumors and lymphomas in comparison to wild-type littermate mice. Intriguingly, these tumors still express Wwox protein, suggesting haploinsuffiency of WWOX itself is cancer predisposing. These results indicate that WWOX is a bona fide tumor suppressor.

  6. Tumor-Induced Myeloid-Derived Suppressor Cells.

    PubMed

    De Sanctis, Francesco; Bronte, Vincenzo; Ugel, Stefano

    2016-06-01

    Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous, immune-suppressive leukocyte population that develops systemically and infiltrates tumors. MDSCs can restrain the immune response through different mechanisms including essential metabolite consumption, reactive oxygen and nitrogen species production, as well as display of inhibitory surface molecules that alter T-cell trafficking and viability. Moreover, MDSCs play a role in tumor progression, acting directly on tumor cells and promoting cancer stemness, angiogenesis, stroma deposition, epithelial-to-mesenchymal transition, and metastasis formation. Many biological and pharmaceutical drugs affect MDSC expansion and functions in preclinical tumor models and patients, often reversing host immune dysfunctions and allowing a more effective tumor immunotherapy.

  7. Tumor Suppressor Genes: A Key to the Cancer Puzzle?

    ERIC Educational Resources Information Center

    Oppenheimer, Steven B.

    1991-01-01

    Author describes developments in understanding of tumor suppressor genes or antioncogenes that he feels is most important breakthrough in solving cancer problem. Describes 1969 starting work of Harris with mouse fibroblast genes and later work of Knudson with retinoblastoma cells. Provides evidence that deletion of chromosome that results in the…

  8. "Ring-fencing" BRCA1 tumor suppressor activity.

    PubMed

    Patel, Ketan J; Crossan, Gerry P; Hodskinson, Michael R G

    2011-12-13

    BRCA1 is a crucial human breast and ovarian cancer tumor suppressor gene. The article by Drost et al. in this issue of Cancer Cell together with a recent paper in Science now provide a clearer picture of how this large and complex protein suppresses tumorigenesis.

  9. Enhanced transfection of brain tumor suppressor genes by photochemical internalization

    NASA Astrophysics Data System (ADS)

    Chou, Chih H.; Sun, Chung-Ho; Zhou, Yi-Hong; Madsen, Steen J.; Hirschberg, Henry

    2011-03-01

    One of many limitations for cancer gene therapy is the inability of the therapeutic gene to transfect a sufficient number of tumor cells. Photochemical internalization (PCI) is a photodynamic therapy-based approach for improving the delivery of macromolecules and genes into the cell cytosol. The utility of PCI for the delivery of a tumor suppressor gene (PAX-6) was investigated in monolayers and spheroids consisting of F98 rat glioma cells.

  10. Tumor-induced immune dysfunctions caused by myeloid suppressor cells.

    PubMed

    Bronte, V; Serafini, P; Apolloni, E; Zanovello, P

    2001-01-01

    In the late 1970s, several findings suggested that accessory cells distinct from lymphocytes might suppress immune reactivity in tumor-bearing hosts. Studies in animal models and patients later confirmed that cells driven to act as dominant immune suppressors by growing cancers could subvert the immune system. These cells have also been termed natural suppressors, a functional definition connoting their ability to hamper various T- and B-lymphocyte responses without prior activation and independently from antigen and MHC restriction. These properties were attributed to distinct cell populations. The phenotypic discrepancies, together with the lack of antigen specificity, have generated serious restraints to research on tumor-induced suppression. Recent evidence indicates that suppressor cells are closely related to immature myeloid precursors and can be found in several situations that can exert adverse effects on the immunotherapy of cancer. The present review is an attempt to address the nature and properties of immature myeloid suppressors and their relationship to dendritic cells and macrophages, with the aim of clarifying the complex network of tumor-induced, negative regulators of the immune system.

  11. The tumor suppressor protein Fhit. A novel interaction with tubulin.

    PubMed

    Chaudhuri, A R; Khan, I A; Prasad, V; Robinson, A K; Ludueña, R F; Barnes, L D

    1999-08-20

    FHIT (fragile histidine triad) is a candidate human tumor suppressor gene located at chromosome 3p14.2, a location that encompasses the FRA3B chromosomal fragile site. Aberrant transcripts have been detected in a variety of primary tumors, and homozygous deletions in the FHIT locus have been detected in different tumor cell lines. The gene product Fhit in vitro possesses the ability to hydrolyze diadenosine 5',5"'-P(1),P(3)-triphosphate (Ap(3)A). The mechanism of action of Fhit as a tumor suppressor is unknown. Because the tubulin-microtubule system plays an important role in cell division and cell proliferation, we investigated the interaction between wild-type Fhit or mutant Fhit (H96N) and tubulin in vitro. The mutant form of Fhit (H96N) lacks Ap(3)A hydrolase activity but retains tumor suppressor activity. We found that both wild-type and mutated forms of Fhit bind to tubulin strongly and specifically with K(d) values of 1.4 and 2.1 microM, respectively. Neither wild-type nor mutant Fhit cause nucleation or formation of microtubules, but in the presence of microtubule-associated proteins, both wild-type and mutant Fhit promote assembly to a greater extent than do microtubule-associated proteins alone, and the microtubules formed appear normal by electron microscopy. Our results suggest the possibility that Fhit may exert its tumor suppressor activity by interacting with microtubules and also indicate that the interaction between Fhit and tubulin is not related to the Ap(3)A hydrolase activity of Fhit.

  12. Isolation of tumor suppressor genes from MEN-1 related neoplasms

    SciTech Connect

    Yavari, R.; Kinder, B.; Bale, A.E.

    1994-09-01

    Multiple Endocrine Neoplasia type 1 (MEN 1) is a cancer predisposition syndrome marked by the development of tumors in specific endocrine tissues such as the pituitary, parathyroid and pancreatic islets. Genetic linkage studies have mapped the MEN 1 gene to 11q13, and allelic loss in related tumors suggests that the gene is a tumor suppressor. Because inactivation of tumor suppressors may be accompanied by underexpression, subtractive hybridization was used to isolate potential candidate genes underexpressed in MEN 1 tumors. cDNA was synthesized from tumor and normal parathyroid tissue by RT-PCR. Biotinylated tumor cDNA was used as a driver and normal cDNA as a tester in subtractive hybridization. Following annealing of the driver and tester amplicons, the biotinylated strands were removed with streptavidin. The subtracted material was then used as a probe to isolate clones from a normal pancreatic islet library. Screening 2 x 10{sup 5} plaques yielded 14 positive clones. Of 6 clones analyzed, 3 were confirmed to be underexpressed in parathyroid tumors. Sequence analysis identified 2 clones as human ribosomal protein S10 (RPS10, chromosome 6) and 1 as the islet amyloid polypeptide (1AP, chromosome 12). The precise function of human RPS10 is not known but the related RPS6 functions as a tumor suppressor in Drosophila. 1AP has been implicated in modulation of G protein activity. The remaining positive clones will be mapped to determine if any fall on chromosome 11q13, and additional subtractions with parathyroid and pancreatic islet neoplasms are underway.

  13. Control of autophagy by oncogenes and tumor suppressor genes.

    PubMed

    Maiuri, M C; Tasdemir, E; Criollo, A; Morselli, E; Vicencio, J M; Carnuccio, R; Kroemer, G

    2009-01-01

    Multiple oncogenes (in particular phosphatidylinositol 3-kinase, PI3K; activated Akt1; antiapoptotic proteins from the Bcl-2 family) inhibit autophagy. Similarly, several tumor suppressor proteins (such as BH3-only proteins; death-associated protein kinase-1, DAPK1; the phosphatase that antagonizes PI3K, PTEN; tuberous sclerosic complex 1 and 2, TSC1 and TSC2; as well as LKB1/STK11) induce autophagy, meaning that their loss reduces autophagy. Beclin-1, which is required for autophagy induction acts as a haploinsufficient tumor suppressor protein, and other essential autophagy mediators (such as Atg4c, UVRAG and Bif-1) are bona fide oncosuppressors. One of the central tumor suppressor proteins, p53 exerts an ambiguous function in the regulation of autophagy. Within the nucleus, p53 can act as an autophagy-inducing transcription factor. Within the cytoplasm, p53 exerts a tonic autophagy-inhibitory function, and its degradation is actually required for the induction of autophagy. The role of autophagy in oncogenesis and anticancer therapy is contradictory. Chronic suppression of autophagy may stimulate oncogenesis. However, once a tumor is formed, autophagy inhibition may be a therapeutic goal for radiosensitization and chemosensitization. Altogether, the current state-of-the art suggests a complex relationship between cancer and deregulated autophagy that must be disentangled by further in-depth investigation.

  14. Inactivation of X-linked tumor suppressor genes in human cancer

    PubMed Central

    Liu, Runhua; Kain, Mandy; Wang, Lizhong

    2015-01-01

    Cancer cells silence autosomal tumor suppressor genes by Knudson’s two-hit mechanism in which loss-of-function mutations and then loss of heterozygosity occur at the tumor suppressor gene loci. However, the identification of X-linked tumor suppressor genes has challenged the traditional theory of “two-hit inactivation” in tumor suppressor genes, introducing the novel concept that a single genetic hit can cause loss of tumor suppressor function. The mechanism through which these genes are silenced in human cancer is unclear, but elucidating the details will greatly enhance our understanding of the pathogenesis of human cancer. Here, we review the identification of X-linked tumor suppressor genes and discuss the potential mechanisms of their inactivation. In addition, we also discuss how the identification of X-linked tumor suppressor genes can potentially lead to new approaches to cancer therapy. PMID:22515449

  15. Inactivation of X-linked tumor suppressor genes in human cancer.

    PubMed

    Liu, Runhua; Kain, Mandy; Wang, Lizhong

    2012-04-01

    Cancer cells silence autosomal tumor suppressor genes by Knudson's two-hit mechanism in which loss-of-function mutations and then loss of heterozygosity occur at the tumor suppressor gene loci. However, the identification of X-linked tumor suppressor genes has challenged the traditional theory of 'two-hit inactivation' in tumor suppressor genes, introducing the novel concept that a single genetic hit can cause loss of tumor suppressor function. The mechanism through which these genes are silenced in human cancer is unclear, but elucidating the details will greatly enhance our understanding of the pathogenesis of human cancer. Here, we review the identification of X-linked tumor suppressor genes and discuss the potential mechanisms of their inactivation. In addition, we also discuss how the identification of X-linked tumor suppressor genes can potentially lead to new approaches in cancer therapy.

  16. Interaction between Nm23 and the tumor suppressor VHL.

    PubMed

    Lin, Chih-Hung; Dammai, Vincent; Adryan, Boris; Hsu, Tien

    2015-02-01

    Among the anti-tumor genes (tumor suppressors and metastasis suppressors), the von-Hippel Lindau gene and the Nm23 family of genes are among the more intriguing ones. Both are small (long and short forms of VHL are 30 and 19 kD, respectively, and Nm23 is ~17 kD), and both possess diverse molecular and cellular functions. Despite extensive studies, the entire spectra of functions and the molecular function-phenotype correlation of these two proteins have not been completely elucidated. In this report, we present data showing these two proteins interact physically. We also summarize and confirm the previous studies that demonstrated the endocytic function of these two genes and further show that the endocytic function of VHL is mediated through the activity of Nm23. These functional and molecular interactions are evolutionarily conserved from Drosophila to human.

  17. ETV1 positively regulates transcription of tumor suppressor ARF

    PubMed Central

    Zynda, Evan; Jackson, Mark W; Bhattacharya, Partho; Kandel, Eugene S

    2013-01-01

    ETV1 (ETS variant 1) is a transcription factor from the ETS family and an oncogene in several types of human malignancies. Paradoxically, a predicted inactivating mutation in ETV1 was previously found in a clone of HT1080 cells with reduced activity of p53. We report that elevated expression of ETV1 makes p53-null tumor cells hypersensitive to restoration of said tumor suppressor. Furthermore, elevated levels of either wild-type ETV1 or its truncated derivative, dETV1, which mimics the product of an oncogenic rearrangement in certain tumors, results in increased expression of mRNA for p14ARF, a known activator of p53. Accordingly, expression of a luciferase reporter, which is driven by a putative ARF promoter, was elevated by concomitant expression of either ETV1 or dETV1. Our observations point to yet another example of a tumor suppressor gene being activated by a potentially oncogenic signal. A better understanding of the mechanisms that allow a cell to bypass such safeguards is needed in order to predict and prevent the development of an oncogene-tolerant state during cancer evolution. PMID:24157551

  18. Jade-1, a candidate renal tumor suppressor that promotes apoptosis.

    PubMed

    Zhou, Mina I; Foy, Rebecca L; Chitalia, Vipul C; Zhao, Jin; Panchenko, Maria V; Wang, Hongmei; Cohen, Herbert T

    2005-08-02

    Medical therapies are lacking for advanced renal cancer, so there is a great need to understand its pathogenesis. Most renal cancers have defects in the von Hippel-Lindau tumor suppressor pVHL. The mechanism by which pVHL protein functions in renal tumor suppression remains unclear. Jade-1 is a short-lived, kidney-enriched transcription factor that is stabilized by direct interaction with pVHL. Loss of Jade-1 stabilization by pVHL correlates with renal cancer risk, making the relationship between Jade-1 and renal cancer compelling. We report that Jade-1 expression was barely detectable in all tested renal cancer cell lines, regardless of VHL status. Strikingly, proteasome inhibitor treatment increased endogenous Jade-1 expression up to 10-fold. Jade-1 inhibited renal cancer cell growth, colony formation, and tumor formation in nude mice. Intriguingly, Jade-1 also affected the pattern of cell growth in monolayer culture and 3D culture. Jade-1 increased apoptosis by 40-50% and decreased levels of antiapoptotic Bcl-2. Antisense Jade-1-expressing cells confirmed these results. Therefore, Jade-1 may suppress renal cancer cell growth in part by increasing apoptosis. Jade-1 may represent a proapoptotic barrier to proliferation that must be overcome generally in renal cancer, perhaps initially by pVHL inactivation and subsequently by increased proteasomal activity. Therefore, Jade-1 may be a renal tumor suppressor.

  19. ANX7, a candidate tumor suppressor gene for prostate cancer

    PubMed Central

    Srivastava, Meera; Bubendorf, Lukas; Srikantan, Vasantha; Fossom, Linda; Nolan, Lisa; Glasman, Mirta; Leighton, Ximena; Fehrle, Wilfred; Pittaluga, Stefania; Raffeld, Mark; Koivisto, Pasi; Willi, Niels; Gasser, Thomas C.; Kononen, Juha; Sauter, Guido; Kallioniemi, Olli P.; Srivastava, Shiv; Pollard, Harvey B.

    2001-01-01

    The ANX7 gene is located on human chromosome 10q21, a site long hypothesized to harbor a tumor suppressor gene(s) (TSG) associated with prostate and other cancers. To test whether ANX7 might be a candidate TSG, we examined the ANX7-dependent suppression of human tumor cell growth, stage-specific ANX7 expression in 301 prostate specimens on a prostate tissue microarray, and loss of heterozygosity (LOH) of microsatellite markers at or near the ANX7 locus. Here we report that human tumor cell proliferation and colony formation are markedly reduced when the wild-type ANX7 gene is transfected into two prostate tumor cell lines, LNCaP and DU145. Consistently, analysis of ANX7 protein expression in human prostate tumor microarrays reveals a significantly higher rate of loss of ANX7 expression in metastatic and local recurrences of hormone refractory prostate cancer as compared with primary tumors (P = 0.0001). Using four microsatellite markers at or near the ANX7 locus, and laser capture microdissected tumor cells, 35% of the 20 primary prostate tumors show LOH. The microsatellite marker closest to the ANX7 locus showed the highest rate of LOH, including one homozygous deletion. We conclude that the ANX7 gene exhibits many biological and genetic properties expected of a TSG and may play a role in prostate cancer progression. PMID:11287641

  20. Therapeutic Targets in the ARF Tumor Suppressor Pathway

    PubMed Central

    Saporita, Anthony J.; Maggi, Leonard B.; Apicelli, Anthony J.; Weber, Jason D.

    2008-01-01

    One of the outstanding fundamental questions in cancer cell biology concerns how cells coordinate cellular growth (or macromolecular synthesis) with cell cycle progression and mitosis. Intuitively, rapidly dividing cells must have some control over these processes; otherwise cells would continue to shrink in volume with every passing cycle, similar to the cytoreductive divisions seen in the very early stages of embryogenesis. The problem is easily solved in unicellular organisms, such as yeast, as their growth rates are entirely dependent on nutrient availability. Multicellular organisms such as mammals, however, must have acquired additional levels of control, as nutrient availability is seldom an issue and the organism has a prodigious capacity to store necessary metabolites in the form of glycogen, lipids, and protein. Furthermore, the specific needs and specialized architecture of tissues must constrain growth for growth’s sake; if not, the necessary function of the organ could be lost. While certainly a myriad of mechanisms for preventing this exist via initiating cell death (e.g. apoptosis, autophagy, necrosis), these all depend on some external cue, such as death signals, hypoxia, lack of nutrients or survival signals. However there must also be some cell autonomous method for surveying against inappropriate growth signals (such as oncogenic stress) that occur in a stochastic fashion, possibly as a result of random mutations. The ARF tumor suppressor seems to fulfill that role, as its expression is near undetectable in normal tissues, yet is potently induced by oncogenic stress (such as overexpression of oncogenic Ras or myc). As a result of induced expression of ARF, the tumor suppressor protein p53 is stabilized and promotes cell cycle arrest. Mutations or epigenetic alterations of the INK4a/Arf locus are second only to p53 mutations in cancer cells, and in some cancers, alterations in both Arf and p53 observed, suggesting that these two tumor

  1. Induction of myeloid-derived suppressor cells by tumor exosomes.

    PubMed

    Xiang, Xiaoyu; Poliakov, Anton; Liu, Cunren; Liu, Yuelong; Deng, Zhong-bin; Wang, Jianhua; Cheng, Ziqiang; Shah, Spandan V; Wang, Gui-Jun; Zhang, Liming; Grizzle, William E; Mobley, Jim; Zhang, Huang-Ge

    2009-06-01

    Myeloid-derived suppressor cells (MDSCs) promote tumor progression. The mechanisms of MDSC development during tumor growth remain unknown. Tumor exosomes (T-exosomes) have been implicated to play a role in immune regulation, however the role of exosomes in the induction of MDSCs is unclear. Our previous work demonstrated that exosomes isolated from tumor cells are taken up by bone marrow myeloid cells. Here, we extend those findings showing that exosomes isolated from T-exosomes switch the differentiation pathway of these myeloid cells to the MDSC pathway (CD11b(+)Gr-1(+)). The resulting cells exhibit MDSC phenotypic and functional characteristics including promotion of tumor growth. Furthermore, we demonstrated that in vivo MDSC mediated promotion of tumor progression is dependent on T-exosome prostaglandin E2 (PGE2) and TGF-beta molecules. T-exosomes can induce the accumulation of MDSCs expressing Cox2, IL-6, VEGF, and arginase-1. Antibodies against exosomal PGE2 and TGF-beta block the activity of these exosomes on MDSC induction and therefore attenuate MDSC-mediated tumor-promoting ability. Exosomal PGE2 and TGF-beta are enriched in T-exosomes when compared with exosomes isolated from the supernatants of cultured tumor cells (C-exosomes). The tumor microenvironment has an effect on the potency of T-exosome mediated induction of MDSCs by regulating the sorting and the amount of exosomal PGE2 and TGF-beta available. Together, these findings lend themselves to developing specific targetable therapeutic strategies to reduce or eliminate MDSC-induced immunosuppression and hence enhance host antitumor immunotherapy efficacy.

  2. RB1: a prototype tumor suppressor and an enigma

    PubMed Central

    Dyson, Nicholas J.

    2016-01-01

    The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients? PMID:27401552

  3. Fastest Time to Cancer by Loss of Tumor Suppressor Genes

    PubMed Central

    Sanchez-Tapia, Cynthia; Wan, Frederic Y.M.

    2014-01-01

    Genetic instability promotes cancer progression (by increasing the probability of cancerous mutations) as well as hinders it (by imposing a higher cell death rate for cells susceptible to cancerous mutation). With the loss of tumor suppressor gene function known to be responsible for a high percentage of breast and colorectal cancer (and a good fraction of lung and other types as well), it is important to understand how genetic instability can be orchestrated toward carcinogenesis. In this context, this paper gives a complete characterization of the optimal (time-varying) cell mutation rate for the fastest time to a target cancerous cell population through the loss of both copies of a tumor suppressor gene (TSG). Similar to the (1-step) oncogene activation model previously analyzed, the optimal mutation rate of the present 2-step model changes qualitatively with the convexity of the (mutation rate dependent) cell death rate. However, the structure of the Hamiltonian for the new model differs significantly and intrinsically from that of the 1-step model and a completely new approach is needed for the solution of the present 2-step problem. Considerable insight on the biology of optimal switching (between corner controls) is extracted from numerical results for cases with nonconvex death rates. PMID:25338553

  4. Transcriptional Regulation of the p16 Tumor Suppressor Gene.

    PubMed

    Kotake, Yojiro; Naemura, Madoka; Murasaki, Chihiro; Inoue, Yasutoshi; Okamoto, Haruna

    2015-08-01

    The p16 tumor suppressor gene encodes a specific inhibitor of cyclin-dependent kinase (CDK) 4 and 6 and is found altered in a wide range of human cancers. p16 plays a pivotal role in tumor suppressor networks through inducing cellular senescence that acts as a barrier to cellular transformation by oncogenic signals. p16 protein is relatively stable and its expression is primary regulated by transcriptional control. Polycomb group (PcG) proteins associate with the p16 locus in a long non-coding RNA, ANRIL-dependent manner, leading to repression of p16 transcription. YB1, a transcription factor, also represses the p16 transcription through direct association with its promoter region. Conversely, the transcription factors Ets1/2 and histone H3K4 methyltransferase MLL1 directly bind to the p16 locus and mediate p16 induction during replicative and premature senescence. In the present review, we discuss the molecular mechanisms by which these factors regulate p16 transcription.

  5. RB1: a prototype tumor suppressor and an enigma.

    PubMed

    Dyson, Nicholas J

    2016-07-01

    The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients?

  6. Phosphorylation is the switch that turns PEA-15 from tumor suppressor to tumor promoter

    PubMed Central

    Sulzmaier, Florian J.; Opoku-Ansah, John; Ramos, Joe W.

    2012-01-01

    Abnormal ERK signaling is implicated in many human diseases including cancer. This signaling cascade is a good target for the therapy of certain malignancies because of its important role in regulating cell proliferation and survival. The small phosphoprotein PEA-15 is a potent regulator of the ERK signaling cascade, and, by acting on this pathway, has been described to have both tumor-suppressor and tumor-promoter functions. However, the exact mechanism by which PEA-15 drives the outcome one way or the other remains unclear. We propose that the cellular environment is crucial in determining PEA-15 protein function by affecting the protein’s phosphorylation state. We hypothesize that only unphosphorylated PEA-15 can act as a tumor-suppressor and that phosphorylation alters the interaction with binding partners to promote tumor development. In order to use PEA-15 as a prognostic marker or therapeutic target it is therefore important to evaluate its phosphorylation status. PMID:22694972

  7. TANGO is a tumor suppressor of malignant melanoma.

    PubMed

    Arndt, Stephanie; Bosserhoff, Anja K

    2006-12-15

    The TANGO gene was originally identified as a new family member of the melanoma inhibitory activity gene family. The gene codes for a 14 kDa protein of so far unknown function. In our study we revealed that TANGO was downregulated or lost in 9 melanoma cell lines when compared to normal melanocytes and in most of the 8 tumor samples analyzed. The losses were associated with advanced stage of the disease. These results were confirmed in situ by immunohistochemistry on 10 paraffin-embedded sections of human malignant melanoma primary tumors and melanoma skin metastases. A small reduction of TANGO was also seen in different benign and atypical nevi when compared to normal skin. For functional analysis of TANGO we evaluated TANGO re-expressing melanoma cell clones and antisense TANGO cell clones with a complete loss of TANGO. Functional assays with TANGO transfected or treated cell lines revealed that TANGO expression reduces motility, whereas reduction of TANGO enhances migration. Our studies, therefore, indicate that reduction of TANGO expression contributes to tumor progression. These results taken together provide the first indications for a tumor suppressor role of TANGO gene in human malignant melanoma.

  8. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration.

    PubMed

    Hesse, Robert G; Kouklis, Gayle K; Ahituv, Nadav; Pomerantz, Jason H

    2015-11-17

    The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species' regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF -p53 axis activation.

  9. Metastasis Suppressors Regulate the Tumor Microenvironment by Blocking Recruitment of Prometastatic Tumor-Associated Macrophages.

    PubMed

    Frankenberger, Casey; Rabe, Daniel; Bainer, Russell; Sankarasharma, Devipriya; Chada, Kiran; Krausz, Thomas; Gilad, Yoav; Becker, Lev; Rosner, Marsha Rich

    2015-10-01

    Triple-negative breast cancer (TNBC) patients have the highest risk of recurrence and metastasis. Because they cannot be treated with targeted therapies, and many do not respond to chemotherapy, they represent a clinically underserved group. TNBC is characterized by reduced expression of metastasis suppressors such as Raf kinase inhibitory protein (RKIP), which inhibits tumor invasiveness. Mechanisms by which metastasis suppressors alter tumor cells are well characterized; however, their ability to regulate the tumor microenvironment and the importance of such regulation to metastasis suppression are incompletely understood. Here, we use species-specific RNA sequencing to show that RKIP expression in tumors markedly reduces the number and metastatic potential of infiltrating tumor-associated macrophages (TAM). TAMs isolated from nonmetastatic RKIP(+) tumors, relative to metastatic RKIP(-) tumors, exhibit a reduced ability to drive tumor cell invasion and decreased secretion of prometastatic factors, including PRGN, and shed TNFR2. RKIP regulates TAM recruitment by blocking HMGA2, resulting in reduced expression of numerous macrophage chemotactic factors, including CCL5. CCL5 overexpression in RKIP(+) tumors restores recruitment of prometastatic TAMs and intravasation, whereas treatment with the CCL5 receptor antagonist Maraviroc reduces TAM infiltration. These results highlight the importance of RKIP as a regulator of TAM recruitment through chemokines such as CCL5. The clinical significance of these interactions is underscored by our demonstration that a signature comprised of RKIP signaling and prometastatic TAM factors strikingly separates TNBC patients based on survival outcome. Collectively, our findings identify TAMs as a previously unsuspected mechanism by which the metastasis-suppressor RKIP regulates tumor invasiveness, and further suggest that TNBC patients with decreased RKIP activity and increased TAM infiltration may respond to macrophage

  10. Notch1 functions as a tumor suppressor in mouse skin.

    PubMed

    Nicolas, Michael; Wolfer, Anita; Raj, Kenneth; Kummer, J Alain; Mill, Pleasantine; van Noort, Mascha; Hui, Chi-chung; Clevers, Hans; Dotto, G Paolo; Radtke, Freddy

    2003-03-01

    Notch proteins are important in binary cell-fate decisions and inhibiting differentiation in many developmental systems, and aberrant Notch signaling is associated with tumorigenesis. The role of Notch signaling in mammalian skin is less well characterized and is mainly based on in vitro studies, which suggest that Notch signaling induces differentiation in mammalian skin. Conventional gene targeting is not applicable to establishing the role of Notch receptors or ligands in the skin because Notch1-/- embryos die during gestation. Therefore, we used a tissue-specific inducible gene-targeting approach to study the physiological role of the Notch1 receptor in the mouse epidermis and the corneal epithelium of adult mice. Unexpectedly, ablation of Notch1 results in epidermal and corneal hyperplasia followed by the development of skin tumors and facilitated chemical-induced skin carcinogenesis. Notch1 deficiency in skin and in primary keratinocytes results in increased and sustained expression of Gli2, causing the development of basal-cell carcinoma-like tumors. Furthermore, Notch1 inactivation in the epidermis results in derepressed beta-catenin signaling in cells that should normally undergo differentiation. Enhanced beta-catenin signaling can be reversed by re-introduction of a dominant active form of the Notch1 receptor. This leads to a reduction in the signaling-competent pool of beta-catenin, indicating that Notch1 can inhibit beta-catenin-mediated signaling. Our results indicate that Notch1 functions as a tumor-suppressor gene in mammalian skin.

  11. Vitamin D receptor, a tumor suppressor in skin.

    PubMed

    Bikle, Daniel D

    2015-05-01

    Vitamin D and calcium are well-established regulators of keratinocyte proliferation and differentiation. Therefore, it was not a great surprise that deletion of the vitamin D receptor (VDR) should predispose the skin to tumor formation, and that the combination of deleting both the VDR and calcium sensing receptor (CaSR) should be especially pro-oncogenic. In this review I have examined 4 mechanisms that appear to underlie the means by which VDR acts as a tumor suppressor in skin. First, DNA damage repair is curtailed in the absence of the VDR, allowing mutations in DNA to accumulate. Second and third involve the increased activation of the hedgehog and β-catenin pathways in the epidermis in the absence of the VDR, leading to poorly regulated proliferation with reduced differentiation. Finally, VDR deletion leads to a shift in the expression of long noncoding RNAs toward a more oncogenic profile. How these different mechanisms interact and their relative importance in the predisposition of the VDR null epidermis to tumor formation remain under active investigation.

  12. The vitamin D receptor: a tumor suppressor in skin.

    PubMed

    Bikle, Daniel David

    2011-01-01

    Epidemiologic evidence supporting a major chemopreventive role for vitamin D in various malignancies is strong. Likewise the use of the active metabolite of vitamin D, 1,25(OH)(2)D(3), and its analogs to prevent and/or treat a wide variety of malignancies in animals is well established. The evidence has been less compelling for epidermal carcinogenesis perhaps because the same agent that produces vitamin D in the skin, UVB radiation (UVR), is also the same agent that results in most epidermal malignancies. However, recent studies indicate that the role of vitamin D and its receptor (VDR) in protecting against the development of epidermal tumors deserves a closer look. One such study found mice lacking the VDR were quite sensitive to epidermal tumor formation following the administration of the carcinogen DMBA. A more recent study showed that these mice were similarly more sensitive to tumor formation following UVR, results we have confirmed. The epidermis of the VDR null mouse is hyperproliferative with gross distortion of hair follicles, structures that may provide the origin for the tumors found in the skin following such treatment. Two interacting pathways critical for epidermal and hair follicle function, beta-catenin and hedgehog (Hh), result in epidermal tumors when they are activated abnormally. Thus, we considered the possibility that loss of VDR predisposes to epidermal tumor formation by activation of either or both beta-catenin and Hh signaling. We determined that all elements of the Hh signaling pathway are upregulated in the epidermis and utricles of the VDR null mouse, and that 1,25(OH)(2)D(3) suppresses the expression of these elements in normal mouse skin. In addition we observed that the transcriptional activity of beta-catenin was increased in keratinocytes lacking the VDR. These results lead us to the hypothesis that the VDR with its ligand 1,25(OH)(2)D(3) functions as a tumor suppressor with respect to epidermal tumor formation in response to

  13. Cigarette smoke induces methylation of the tumor suppressor gene NISCH

    PubMed Central

    Ostrow, Kimberly Laskie; Michalidi, Christina; Guerrero-Preston, Rafael; Hoque, Mohammad O.; Greenberg, Alissa; Rom, William; Sidransky, David

    2013-01-01

    We have previously identified a putative tumor suppressor gene, NISCH, whose promoter is methylated in lung tumor tissue as well as in plasma obtained from lung cancer patients. NISCH was observed to be more frequently methylated in smoker lung cancer patients than in non-smoker lung cancer patients. Here, we investigated the effect of tobacco smoke exposure on methylation of the NISCH gene. We tested methylation of NISCH after oral keratinocytes were exposed to mainstream and side stream cigarette smoke extract in culture. Methylation of the promoter region of the NISCH gene was also evaluated in plasma obtained from lifetime non-smokers and light smokers (< 20 pack/year), with and without lung tumors, and heavy smokers (20+ pack/year) without disease. Promoter methylation of NISCH was tested by quantitative fluorogenic real-time PCR in all samples. Promoter methylation of NISCH occurred after exposure to mainstream tobacco smoke as well as to side stream tobacco smoke in normal oral keratinocyte cell lines. NISCH methylation was also detected in 68% of high-risk, heavy smokers without detectable tumors. Interestingly, in light smokers, NISCH methylation was present in 69% of patients with lung cancer and absent in those without disease. Our pilot study indicates that tobacco smoke induces methylation changes in the NISCH gene promoter before any detectable cancer. Methylation of the NISCH gene was also found in lung cancer patients’ plasma samples. After confirming these findings in longitudinally collected plasma samples from high-risk populations (such as heavy smokers), examining patients for hypermethylation of the NISCH gene may aid in identifying those who should undergo additional screening for lung cancer. PMID:23503203

  14. Epigenetic silencing of tumor suppressor genes: Paradigms, puzzles, and potential.

    PubMed

    Kazanets, Anna; Shorstova, Tatiana; Hilmi, Khalid; Marques, Maud; Witcher, Michael

    2016-04-01

    Cancer constitutes a set of diseases with heterogeneous molecular pathologies. However, there are a number of universal aberrations common to all cancers, one of these being the epigenetic silencing of tumor suppressor genes (TSGs). The silencing of TSGs is thought to be an early, driving event in the oncogenic process. With this in consideration, great efforts have been made to develop small molecules aimed at the restoration of TSGs in order to limit tumor cell proliferation and survival. However, the molecular forces that drive the broad epigenetic reprogramming and transcriptional repression of these genes remain ill-defined. Undoubtedly, understanding the molecular underpinnings of transcriptionally silenced TSGs will aid us in our ability to reactivate these key anti-cancer targets. Here, we describe what we consider to be the five most logical molecular mechanisms that may account for this widely observed phenomenon: 1) ablation of transcription factor binding, 2) overexpression of DNA methyltransferases, 3) disruption of CTCF binding, 4) elevation of EZH2 activity, 5) aberrant expression of long non-coding RNAs. The strengths and weaknesses of each proposed mechanism is highlighted, followed by an overview of clinical efforts to target these processes.

  15. T-cell intracellular antigens function as tumor suppressor genes.

    PubMed

    Sánchez-Jiménez, C; Ludeña, M D; Izquierdo, J M

    2015-03-05

    Knockdown of T-cell intracellular antigens TIA1 and TIAR in transformed cells triggers cell proliferation and tumor growth. Using a tetracycline-inducible system, we report here that an increased expression of TIA1 or TIAR in 293 cells results in reduced rates of cell proliferation. Ectopic expression of these proteins abolish endogenous TIA1 and TIAR levels via the regulation of splicing of their pre-mRNAs, and partially represses global translation in a phospho-eukaryotic initiation factor 2 alpha-dependent manner. This is accompanied by cell cycle arrest at G1/S and cell death through caspase-dependent apoptosis and autophagy. Genome-wide profiling illustrates a selective upregulation of p53 signaling pathway-related genes. Nude mice injected with doxycycline-inducible cells expressing TIA1 or TIAR retard, or even inhibit, growth of xenotumors. Remarkably, low expressions of TIA1 and TIAR correlate with poor prognosis in patients with lung squamous cell carcinoma. These findings strongly support the concept that TIA proteins act as tumor suppressor genes.

  16. Epigenetic regulator Smchd1 functions as a tumor suppressor.

    PubMed

    Leong, Huei San; Chen, Kelan; Hu, Yifang; Lee, Stanley; Corbin, Jason; Pakusch, Miha; Murphy, James M; Majewski, Ian J; Smyth, Gordon K; Alexander, Warren S; Hilton, Douglas J; Blewitt, Marnie E

    2013-03-01

    SMCHD1 is an epigenetic modifier of gene expression that is critical to maintain X chromosome inactivation. Here, we show in mouse that genetic inactivation of Smchd1 accelerates tumorigenesis in male mice. Loss of Smchd1 in transformed mouse embryonic fibroblasts increased tumor growth upon transplantation into immunodeficient nude mice. In addition, loss of Smchd1 in Eμ-Myc transgenic mice that undergo lymphomagenesis reduced disease latency by 50% relative to control animals. In premalignant Eμ-Myc transgenic mice deficient in Smchd1, there was an increase in the number of pre-B cells in the periphery, likely accounting for the accelerated disease in these animals. Global gene expression profiling suggested that Smchd1 normally represses genes activated by MLL chimeric fusion proteins in leukemia, implying that Smchd1 loss may work through the same pathways as overexpressed MLL fusion proteins do in leukemia and lymphoma. Notably, we found that SMCHD1 is underexpressed in many types of human hematopoietic malignancy. Together, our observations collectively highlight a hitherto uncharacterized role for SMCHD1 as a candidate tumor suppressor gene in hematopoietic cancers.

  17. Regulation of cell signaling and apoptosis by tumor suppressor WWOX

    PubMed Central

    Lo, Jui-Yen; Chou, Ying-Tsen; Lai, Feng-Jie

    2015-01-01

    Human fragile WWOX gene encodes a tumor suppressor WW domain-containing oxidoreductase (named WWOX, FOR, or WOX1). Functional suppression of WWOX prevents apoptotic cell death induced by a variety of stress stimuli, such as tumor necrosis factor, UV radiation, and chemotherapeutic drug treatment. Loss of WWOX gene expression due to gene deletions, loss of heterozygosity, chromosomal translocations, or epigenetic silencing is frequently observed in human malignant cancer cells. Acquisition of chemoresistance in squamous cell carcinoma, osteosarcoma, and breast cancer cells is associated with WWOX deficiency. WWOX protein physically interacts with many signaling molecules and exerts its regulatory effects on gene transcription and protein stability and subcellular localization to control cell survival, proliferation, differentiation, autophagy, and metabolism. In this review, we provide an overview of the recent advances in understanding the molecular mechanisms by which WWOX regulates cellular functions and stress responses. A potential scenario is that activation of WWOX by anticancer drugs is needed to overcome chemoresistance and trigger cancer cell death, suggesting that WWOX can be regarded as a prognostic marker and a candidate molecule for targeted cancer therapies. PMID:25595191

  18. Expression of the p16{sup INK4a} tumor suppressor gene in rodent lung tumors

    SciTech Connect

    Swafford, D.S.; Tesfaigzi, J.; Belinsky, S.A.

    1995-12-01

    Aberrations on the short arm of chromosome 9 are among the earliest genetic changes in human cancer. p16{sup INK4a} is a candidate tumor suppressor gene that lies within human 9p21, a chromosome region associated with frequent loss of heterozygosity in human lung tumors. The p16{sup INK4a} protein functions as an inhibitor of cyclin D{sub 1}-dependent kinases that phosphorylate the retinoblastoma (Rb) tumor suppressor gene product enabling cell-cycle progression. Thus, overexpression of cyclin D{sub 1}, mutation of cyclin-dependent kinase genes, or loss of p16{sup INK4a} function, can all result in functional inactivation of Rb. Inactivation of Rb by mutation or deletion can result in an increase in p16{sup INK4a} transcription, suggesting that an increased p16{sup INK4a} expression in a tumor cell signals dysfunction of the pathway. The p16{sup (INK4a)} gene, unlike some tumor suppressor genes, is rarely inactivated by mutation. Instead, the expression of this gene is suppressed in some human cancers by hypermethylation of the CpG island within the first exon or by homozygous deletion: 686. Chromosome losses have been observed at 9p21 syntenic loci in tumors of the mouse and rat, two species often used as animal models for pulmonary carcinogenesis. Expression of p16{sup INK4a} is lost in some mouse tumor cell lines, often due to homozygous deletion. These observations indicate that p16{sup INK4a} dysfunction may play a role in the development of neoplasia in rodents as well as humans. The purpose of the current investigation was to define the extent to which p16{sup INK4a} dysfunction contributes to the development of rodent lung tumors and to determine the mechanism of inactivation of the gene. There is no evidence to suggest a loss of function of the p16{sup INK4a} tumor suppressor gene in these primary murine lung tumors by mutation, deletion, or methylation.

  19. Targeting the BRCA1/2 tumor suppressors.

    PubMed

    Rosen, Eliot M; Pishvaian, Michael J

    2014-01-01

    The breast cancer susceptibility genes BRCA1 and BRCA2 are classic tumor suppressor genes that exhibit an autosomal dominant pattern of inheritance with high penetrance. BRCA carriers inherit one mutant BRCA allele and one wild-type allele; and the wild-type allele is invariably deleted or mutated within the tumor. These genes function as caretakers in the maintenance of genomic stability, in part, by participating in homology-directed DNA repair (HDR), an error- free mechanism for the repair of double-strand breaks (DSBs). PARP1 (poly (ADP-ribose) polymerase 1) is an enzyme that functions in the base excision repair (BER) pathway, where its ability to post-translationally modify histones and DNA damage response proteins is required for repair of single-strand breaks (SSBs). In 2005, it was observed that knockdown of PARP1 or treatment with a small molecule PARP inhibitor was far more toxic to cells with BRCA1 or BRCA2 mutations than BRCA1/2-competent cells. This observation is an example of "synthetic lethality", a concept whereby two gene mutations combine to cause cell death, when neither mutation alone is lethal. These results spawned the idea to use PARP inhibitors to treat BRCA1/2 mutant cancers. Here, we will review the basic science underlying the discoveries described above, the preclinical research, and the clinical trials designed to exploit the sensitivity of BRCA1/2 mutant tumor cells to PARP inhibitors. We will also describe problems associated with the use of these agents, including development and mechanisms of drug resistance; and we will provide a forward look at new agents and strategies currently under development.

  20. Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4

    PubMed Central

    Schmid, Tobias; Blees, Johanna S.; Bajer, Magdalena M.; Wild, Janine; Pescatori, Luca; Cuzzucoli Crucitti, Giuliana; Scipione, Luigi; Costi, Roberta; Henrich, Curtis J.; Brüne, Bernhard; Colburn, Nancy H.; Di Santo, Roberto

    2016-01-01

    The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyl)disulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2–4) or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6). We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted. PMID:26982744

  1. PML tumor suppressor protein is required for HCV production

    SciTech Connect

    Kuroki, Misao; Ariumi, Yasuo; Hijikata, Makoto; Ikeda, Masanori; Dansako, Hiromichi; Wakita, Takaji; Shimotohno, Kunitada; Kato, Nobuyuki

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer PML tumor suppressor protein is required for HCV production. Black-Right-Pointing-Pointer PML is dispensable for HCV RNA replication. Black-Right-Pointing-Pointer HCV could not alter formation of PML-NBs. Black-Right-Pointing-Pointer INI1 and DDX5, PML-related proteins, are involved in HCV life cycle. -- Abstract: PML tumor suppressor protein, which forms discrete nuclear structures termed PML-nuclear bodies, has been associated with several cellular functions, including cell proliferation, apoptosis and antiviral defense. Recently, it was reported that the HCV core protein colocalizes with PML in PML-NBs and abrogates the PML function through interaction with PML. However, role(s) of PML in HCV life cycle is unknown. To test whether or not PML affects HCV life cycle, we examined the level of secreted HCV core and the infectivity of HCV in the culture supernatants as well as the level of HCV RNA in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, stably expressing short hairpin RNA targeted to PML. In this context, the level of secreted HCV core and the infectivity in the supernatants from PML knockdown cells was remarkably reduced, whereas the level of HCV RNA in the PML knockdown cells was not significantly affected in spite of very effective knockdown of PML. In fact, we showed that PML is unrelated to HCV RNA replication using the subgenomic HCV-JFH1 replicon RNA, JRN/3-5B. Furthermore, the infectivity of HCV-like particle in the culture supernatants was significantly reduced in PML knockdown JRN/3-5B cells expressing core to NS2 coding region of HCV-JFH1 genome using the trans-packaging system. Finally, we also demonstrated that INI1 and DDX5, the PML-related proteins, are involved in HCV production. Taken together, these findings suggest that PML is required for HCV production.

  2. Mapping a tumor suppressor gene in 11p15.5

    SciTech Connect

    Reid, L.; West, A.; Gioeli, D.

    1994-09-01

    We are mapping a tumor suppressor gene in 11p15.5 which is associated with Wilms` tumors (WT), a pediatric kidney cancer. This gene was identified in a functional assay that analyzes the effect of human chromosomes on tumorigenicity by transferring them into the G401 WT cell line. WT hybrids containing an introduced t(X;11) chromosome do not form tumors after subcutaneous injection into nude mice, while other hybrids with different introduced chromosomes remain tumorigenic. In order to better map the tumor suppressor gene, we created a series of deletions in the t(X;11) chromosomes by {gamma}-radiation. Interestingly, three of the radiation-reduced chromosomes are indistinguishable as determined by cytogenetic, Southern blot, and PCR analyses. Upon transfer of these chromosomes into the G401 WT cells, one of the chromosomes retains tumor suppressor activity, while the two other chromosomes lack this ability. We propose two hypotheses to explain the functional difference observed between the indistinguishable chromosomes. First, the chromosome with suppressor activity may contain a region of DNA absent in the other two chromosomes. This proposal would localize the tumor suppressor gene to a 200 kb region of 11p15.5 between D11S648 and D11S601. Alternatively, the indistinguishable chromosomes may be derived from the same clone and their functional differences may indicate that the tumor suppressor gene is imprinted. That is, the tumor suppressor gene may be present on each of the three chromosomes, but not expressed on two of them due to imprinting differences. The H19 gene, located in 11p15.5, is imprinted and was recently shown to have tumor suppressor activity. However, H19 expression does not correlate with tumor suppression in our assay. Instead, we may be tracking a new imprinted gene in 11p15.5.

  3. Allelotyping in Wilms tumors identifies a putative third tumor suppressor gene on chromosome 11

    SciTech Connect

    Radice, P.; Benedetti, V.D.; Mondini, P.

    1995-06-10

    An analysis of loss of heterozygosity for markers on both the short and the long arm of chromosome 11 was performed in 24 sporadic Wilms tumors. Six cases (25%) showed allelic losses involving the entire chromosome. In one case (4%) the loss was restricted solely to the WT1 gene on band p13. Two cases (8%) displayed allelic losses for WT1 and for markers on band p15.5, where the putative tumor suppressor gene WT2 has been mapped, but retained heterozygosity for markers on the long arm. In three tumors (13%) the loss of heterozygosity involved markers mapped to chromosomal regions p15.5 and q23.3-qter, but did not affect WT1 and markers on q12-q13. Altogether, the proportion of cases showing allelic losses at the distal region of 11q (37%) was comparable to that of cases with LOH affecting the WT1 (37%) or the WT2 (46%) loci, thus suggesting the existence of a third chromosome 11 tumor suppressor gene involved in the pathogenesis of Wilms tumors. 51 refs., 1 fig., 1 tab.

  4. Akt phosphorylates and regulates Pdcd4 tumor suppressor protein.

    PubMed

    Palamarchuk, Alexey; Efanov, Alexey; Maximov, Vadim; Aqeilan, Rami I; Croce, Carlo M; Pekarsky, Yuri

    2005-12-15

    Programmed cell death 4 (Pdcd4) is a tumor suppressor protein that interacts with eukaryotic initiation factor 4A and inhibits protein synthesis. Pdcd4 also suppresses the transactivation of activator protein-1 (AP-1)-responsive promoters by c-Jun. The Akt (protein kinase B) serine/threonine kinase is a key mediator of phosphoinositide 3-kinase pathway involved in the regulation of cell proliferation, survival, and growth. Because Pdcd4 has two putative Akt phosphorylation sites at Ser(67) and Ser(457), we investigated whether Akt phosphorylates and regulates Pdcd4. Our results show that Akt specifically phosphorylates Ser(67) and Ser(457) residues of Pdcd4 in vitro and in vivo. We further show that phosphorylation of Pdcd4 by Akt causes nuclear translocation of Pdcd4. Using luciferase assay, we show that phosphorylation of Pdcd4 by Akt also causes a significant decrease of the ability of Pdcd4 to interfere with the transactivation of AP-1-responsive promoter by c-Jun.

  5. Tumor suppressor p53 protects mice against Listeria monocytogenes infection

    PubMed Central

    Wang, Shaohui; Liu, Pingping; Wei, Jianchao; Zhu, Zixiang; Shi, Zixue; Shao, Donghua; Ma, Zhiyong

    2016-01-01

    Tumor suppressor p53 is involved in regulating immune responses, which contribute to antitumor and antiviral activity. However, whether p53 has anti-bacterial functions remains unclear. Listeria monocytogenes (LM) causes listeriosis in humans and animals, and it is a powerful model for studying innate and adaptive immunity. In the present study, we illustrate an important regulatory role of p53 during LM infection. p53 knockout (p53KO) mice were more susceptible to LM infection, which was manifested by a shorter survival time and lower survival rate. p53KO mice showed significant impairments in LM eradication. Knockdown of p53 in RAW264.7 and HeLa cells resulted in increased invasion and intracellular survival of LM. Furthermore, the invasion and intracellular survival of LM was inhibited in p53-overexpressing RAW264.7 and HeLa cells. LM-infected p53KO mice exhibited severe clinical symptoms and organ injury, presumably because of the abnormal production of the pro-inflammatory cytokines TNF-α, IL-6, IL-12, and IL-18. Decreased IFN-γ and GBP1 productions were observed in LM-infected p53-deficient mice or cells. The combination of these defects likely resulted in the overwhelming LM infection in the p53KO mice. These observations indicate that p53 serves as an important regulator of the host innate immune that protects against LM infection. PMID:27644341

  6. Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport.

    PubMed

    Rexhepaj, Rexhep; Rotte, Anand; Gu, Shuchen; Michael, Diana; Pasham, Venkanna; Wang, Kan; Kempe, Daniela S; Ackermann, Teresa F; Brücher, Björn; Fend, Falko; Föller, Michael; Lang, Florian

    2011-05-01

    Loss of function mutations of the tumor suppressor gene adenomatous polyposis coli (APC) underly the familial adenomatous polyposis. Mice carrying an inactivating mutation in the apc gene (apc (Min/+)) similarly develop intestinal polyposis. APC is effective at least in part by degrading β-catenin and lack of APC leads to markedly enhanced cellular β-catenin levels. β-Catenin has most recently been shown to upregulate the Na+/K+ ATPase. The present study, thus, explored the possibility that APC could influence intestinal transport. The abundance and localization of β-catenin were determined utilizing Western blotting and confocal microscopy, the activity of the electrogenic glucose carrier (SGLT1) was estimated from the glucose-induced current in jejunal segments utilizing Ussing chamber experiments and the Na+/H+ exchanger (NHE3) activity from Na+ -dependent re-alkalinization of cytosolic pH (ΔpH(i)) following an ammonium pulse employing BCECF fluorescence. As a result, β-catenin abundance in intestinal tissue was significantly higher in apc (Min/+) mice than in wild-type mice (apc (+/+)). The β-catenin protein was localized in the basolateral membrane. Both, the glucose-induced current and ΔpH(i) were significantly higher in apc (Min/+) mice than in apc (+/+) mice. In conclusion, intestinal electrogenic transport of glucose and intestinal Na+/H+ exchanger activity are both significantly enhanced in apc (Min/+) mice, pointing to a role of APC in the regulation of epithelial transport.

  7. The retinoblastoma tumor suppressor and stem cell biology.

    PubMed

    Sage, Julien

    2012-07-01

    Stem cells play a critical role during embryonic development and in the maintenance of homeostasis in adult individuals. A better understanding of stem cell biology, including embryonic and adult stem cells, will allow the scientific community to better comprehend a number of pathologies and possibly design novel approaches to treat patients with a variety of diseases. The retinoblastoma tumor suppressor RB controls the proliferation, differentiation, and survival of cells, and accumulating evidence points to a central role for RB activity in the biology of stem and progenitor cells. In some contexts, loss of RB function in stem or progenitor cells is a key event in the initiation of cancer and determines the subtype of cancer arising from these pluripotent cells by altering their fate. In other cases, RB inactivation is often not sufficient to initiate cancer but may still lead to some stem cell expansion, raising the possibility that strategies aimed at transiently inactivating RB might provide a novel way to expand functional stem cell populations. Future experiments dedicated to better understanding how RB and the RB pathway control a stem cell's decisions to divide, self-renew, or give rise to differentiated progeny may eventually increase our capacity to control these decisions to enhance regeneration or help prevent cancer development.

  8. Functional involvement of human discs large tumor suppressor in cytokinesis

    SciTech Connect

    Unno, Kenji; Hanada, Toshihiko; Chishti, Athar H.

    2008-10-15

    Cytokinesis is the final step of cell division that completes the separation of two daughter cells. We found that the human discs large (hDlg) tumor suppressor homologue is functionally involved in cytokinesis. The guanylate kinase (GUK) domain of hDlg mediates the localization of hDlg to the midbody during cytokinesis, and over-expression of the GUK domain in U2OS and HeLa cells impaired cytokinesis. Mouse embryonic fibroblasts (MEFs) derived from dlg mutant mice contained an increased number of multinucleated cells and showed reduced proliferation in culture. A kinesin-like motor protein, GAKIN, which binds directly to the GUK domain of hDlg, exhibited a similar intracellular distribution pattern with hDlg throughout mitosis and localized to the midbody during cytokinesis. However, the targeting of hDlg and GAKIN to the midbody appeared to be independent of each other. The midbody localization of GAKIN required its functional kinesin-motor domain. Treatment of cells with the siRNA specific for hDlg and GAKIN caused formation of multinucleated cells and delayed cytokinesis. Together, these results suggest that hDlg and GAKIN play functional roles in the maintenance of midbody architecture during cytokinesis.

  9. Common Fragile Site Tumor Suppressor Genes and Corresponding Mouse Models of Cancer

    PubMed Central

    Drusco, Alessandra; Pekarsky, Yuri; Costinean, Stefan; Antenucci, Anna; Conti, Laura; Volinia, Stefano; Aqeilan, Rami I.; Huebner, Kay; Zanesi, Nicola

    2011-01-01

    Chromosomal common fragile sites (CFSs) are specific mammalian genomic regions that show an increased frequency of gaps and breaks when cells are exposed to replication stress in vitro. CFSs are also consistently involved in chromosomal abnormalities in vivo related to cancer. Interestingly, several CFSs contain one or more tumor suppressor genes whose structure and function are often affected by chromosomal fragility. The two most active fragile sites in the human genome are FRA3B and FRA16D where the tumor suppressor genes FHIT and WWOX are located, respectively. The best approach to study tumorigenic effects of altered tumor suppressors located at CFSs in vivo is to generate mouse models in which these genes are inactivated. This paper summarizes our present knowledge on mouse models of cancer generated by knocking out tumor suppressors of CFS. PMID:21318118

  10. Common fragile site tumor suppressor genes and corresponding mouse models of cancer.

    PubMed

    Drusco, Alessandra; Pekarsky, Yuri; Costinean, Stefan; Antenucci, Anna; Conti, Laura; Volinia, Stefano; Aqeilan, Rami I; Huebner, Kay; Zanesi, Nicola

    2011-01-01

    Chromosomal common fragile sites (CFSs) are specific mammalian genomic regions that show an increased frequency of gaps and breaks when cells are exposed to replication stress in vitro. CFSs are also consistently involved in chromosomal abnormalities in vivo related to cancer. Interestingly, several CFSs contain one or more tumor suppressor genes whose structure and function are often affected by chromosomal fragility. The two most active fragile sites in the human genome are FRA3B and FRA16D where the tumor suppressor genes FHIT and WWOX are located, respectively. The best approach to study tumorigenic effects of altered tumor suppressors located at CFSs in vivo is to generate mouse models in which these genes are inactivated. This paper summarizes our present knowledge on mouse models of cancer generated by knocking out tumor suppressors of CFS.

  11. The Retinoblastoma Tumor Suppressor Transcriptionally Represses Pak1 in Osteoblasts

    PubMed Central

    Sosa-García, Bernadette; Vázquez-Rivera, Viviana; González-Flores, Jonathan N.; Engel, Brienne E.; Cress, W. Douglas; Santiago-Cardona, Pedro G.

    2015-01-01

    We previously characterized the retinoblastoma tumor suppressor protein (Rb) as a regulator of adherens junction assembly and cell-to-cell adhesion in osteoblasts. This is a novel function since Rb is predominantly known as a cell cycle repressor. Herein, we characterized the molecular mechanisms by which Rb performs this function, hypothesizing that Rb controls the activity of known regulators of adherens junction assembly. We found that Rb represses the expression of the p21-activated protein kinase (Pak1), an effector of the small Rho GTPase Rac1. Rac1 is a well-known regulator of adherens junction assembly whose increased activity in cancer is linked to perturbations of intercellular adhesion. Using nuclear run-on and luciferase reporter transcription assays, we found that Pak1 repression by Rb is transcriptional, without affecting Pak1 mRNA and protein stability. Pak1 promoter bioinformatics showed multiple E2F1 binding sites within 155 base pairs of the transcriptional start site, and a Pak1-promoter region containing these E2F sites is susceptible to transcriptional inhibition by Rb. Chromatin immunoprecipitations showed that an Rb-E2F complex binds to the region of the Pak1 promoter containing the E2F1 binding sites, suggesting that Pak1 is an E2F target and that the repressive effect of Rb on Pak1 involves blocking the trans-activating capacity of E2F. A bioinformatics analysis showed elevated Pak1 expression in several solid tumors relative to adjacent normal tissue, with both Pak1 and E2F increased relative to normal tissue in breast cancer, supporting a cancer etiology for Pak1 up-regulation. Therefore, we propose that by repressing Pak1 expression, Rb prevents Rac1 hyperactivity usually associated with cancer and related to cytoskeletal derangements that disrupt cell adhesion, consequently enhancing cancer cell migratory capacity. This de-regulation of cell adhesion due to Rb loss could be part of the molecular events associated with cancer progression

  12. Control of glutamine metabolism by the tumor suppressor Rb.

    PubMed

    Reynolds, M R; Lane, A N; Robertson, B; Kemp, S; Liu, Y; Hill, B G; Dean, D C; Clem, B F

    2014-01-30

    Retinoblastoma (Rb) protein is a tumor suppressor that is dysregulated in a majority of human cancers. Rb functions to inhibit cell cycle progression in part by directly disabling the E2F family of cell cycle-promoting transcription factors. Because the de novo synthesis of multiple glutamine-derived anabolic precursors is required for cell cycle progression, we hypothesized that Rb also may directly regulate proteins involved in glutamine metabolism. We examined glutamine metabolism in mouse embryonic fibroblasts (MEFs) isolated from mice that have triple knock-outs (TKO) of all three Rb family members (Rb-1, Rbl1 and Rbl2) and found that loss of global Rb function caused a marked increase in (13)C-glutamine uptake and incorporation into glutamate and tricarboxylic acid cycle (TCA) intermediates in part via upregulated expression of the glutamine transporter ASCT2 and the activity of glutaminase 1 (GLS1). The Rb-controlled transcription factor E2F-3 altered glutamine uptake by direct regulation of ASCT2 mRNA and protein expression, and E2F-3 was observed to associate with the ASCT2 promoter. We next examined the functional consequences of the observed increase in glutamine uptake and utilization and found that glutamine exposure potently increased oxygen consumption, whereas glutamine deprivation selectively decreased ATP concentration in the Rb TKO MEFs but not the wild-type (WT) MEFs. In addition, TKO MEFs exhibited elevated production of glutathione from exogenous glutamine and had increased expression of gamma-glutamylcysteine ligase relative to WT MEFs. Importantly, this metabolic shift towards glutamine utilization was required for the proliferation of Rb TKO MEFs but not for the proliferation of the WT MEFs. Last, addition of the TCA cycle intermediate α-ketoglutarate to the Rb TKO MEFs reversed the inhibitory effects of glutamine deprivation on ATP, GSH levels and viability. Taken together, these studies demonstrate that the Rb/E2F cascade directly

  13. Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome 11p15.5.

    DTIC Science & Technology

    1996-07-01

    Noblett, B. D., Pedone, C. A. Chromosome llp 15 deletions in human malignant astrocytomas and primitive neuroectodermal tumors . Genomics 14: 799-801...AD GRANT NUMBER: DAMDI7-94-J-4175 TITLE: Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome 11p15.5 PRINCIPAL INVESTIGATOR: Tracy...SUBTITLE 5. FUNDING NUMBERS Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome 11p15.5 DAMD17-94-J-4175 6. AUTHOR(S) Tracy Moore, Ph.D. 7

  14. B7x and myeloid-derived suppressor cells in the tumor microenvironment

    PubMed Central

    Jeon, Hyungjun; Ohaegbulam, Kim C; Abadi, Yael M; Zang, Xingxing

    2013-01-01

    A new study demonstrates the tumorigenic functions of B7x and reveals a link between B7x and myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment. We propose that the binding of B7x to a hitherto unidentified receptor on MDSCs may stimulate their proliferation and/or immunosuppressive functions, hence promoting tumor growth. PMID:24073367

  15. [The activity of nonspecific bone marrow and spleen suppressors in the latent period of tumor growth].

    PubMed

    Ogreba, V I; Kusmartsev, S A; Vasil'ev, N V

    1988-01-01

    Female A/Sn mice aged 2-3 and 11-14 months (with spontaneous adenocarcinomas of the mammary gland and tumor-free) and C57Bl/6 mice were followed after treatment with DMBA. Suppressor cells were tested for the ability to inhibit in vivo antibody responses to sheep erythrocytes by adoptively syngeneically transferred cells. It was demonstrated that the activity of nonspecific suppressors of the bone marrow and spleen increases considerably in the precancer period.

  16. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration

    PubMed Central

    Hesse, Robert G; Kouklis, Gayle K; Ahituv, Nadav; Pomerantz, Jason H

    2015-01-01

    The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species’ regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF –p53 axis activation. DOI: http://dx.doi.org/10.7554/eLife.07702.001 PMID:26575287

  17. Role of the ARF Tumor Suppressor in Prostate Cancer

    DTIC Science & Technology

    2005-10-01

    Schreiner , Y. Yoneda, M. Yanagida, S. Horinouchi, and M. Yoshida. 1998. Leptomycin B inhibition of signal-me- diated nuclear export by direct binding...suppressor inhibits ribosomal RNA processing. Mol. Cell 11:415– 424. 50. Tao , W., and A. J. Levine. 1999. Nucleocytoplasmic shuttling of oncoprotein

  18. Chromosomal localization of putative tumor-suppressor genes in several human cancers

    SciTech Connect

    Yokota, Jun; Sugimura, Takashi; Terada, Masaaki )

    1991-06-01

    Restriction-fragment-length polymorphism analysis was performed on several different types of human cancers, including carcinoma of the uterine cervix, neuroblastoma, hepatocellular carcinoma, pheochromocytoma, stomach cancer, and small-cell lung carcinoma (SCLC), to determine the chromosomal loci of putative tumor-suppressor genes in each type of tumor because loss of heterozygosity (LOH) is supposed to unmask the recessive mutation of tumor-suppressor gene in the remaining allele. Chromosomal loci showing frequent LOH differed among these tumors, suggesting that there are several tumor-suppressor genes in the human genome and that critical genes for the development of each type of tumor are different. In some cases LOH was observed in the early stage of tumor such as chromosome 3p loss in carcinoma of the uterine cervix, and in other cases it was observed only in the advanced stage of tumor such as chromosomes 4 and 16q loss in hepatocellular carcinoma. These results suggest that there are two different types of tumor-suppressor genes: one is the gene whose inactivation is responsible for malignant transformation of a normal cell and the other is the gene whose inactivation is responsible for the progression of a tumor cell. In SCLC, LOH at three different chromosomal loci, 3p, 13q, and 17p, was simultaneously observed in nearly 100% of tumors. It was observed even in stage I tumors and an untreated tumor, and it occurred prior to N-myc amplification. These results may imply that at least six genetic alterations are necessary to convert a normal cell into a fully malignant cancer cell in SCLC.

  19. The nature of myeloid-derived suppressor cells in the tumor microenvironment

    PubMed Central

    Gabrilovich, Dmitry I.

    2016-01-01

    Myeloid-derived suppressor cells (MDSC) are one of the major components of the tumor microenvironment. The main feature of these cells is their potent immune suppressive activity. MDSC are generated in the bone marrow, and in tumor-bearing hosts, migrate to peripheral lymphoid organs and the tumor to contribute to the formation of the tumor microenvironment. Recent findings have revealed differences in the function and fate of MDSC in the tumor and peripheral lymphoid organs. We review these findings here, and in this context we discuss the current understanding as to the nature of these differences, the underlying mechanisms, and their potential impact on the regulation of tumor progression. PMID:26858199

  20. Frequent alteration of the tumor suppressor gene APC in sporadic canine colorectal tumors.

    PubMed

    Youmans, Lydia; Taylor, Cynthia; Shin, Edwin; Harrell, Adrienne; Ellis, Angela E; Séguin, Bernard; Ji, Xinglai; Zhao, Shaying

    2012-01-01

    Sporadic canine colorectal cancers (CRCs) should make excellent models for studying the corresponding human cancers. To molecularly characterize canine CRC, we investigated exonic sequence mutations of adenomatous polyposis coli (APC), the best known tumor suppressor gene of human CRC, in 23 sporadic canine colorectal tumors, including 8 adenomas and 15 adenocarcinomas, via exon-resequencing analysis. As a comparison, we also performed the same sequencing analysis on 10 other genes, either located at human 5q22 (the same locus as APC) or 18q21 (also frequently altered in human CRC), or known to play a role in human carcinogenesis. We noted that APC was the most significantly mutated gene in both canine adenomas and adenocarcinomas among the 11 genes examined. Significantly, we detected large deletions of ≥ 10 bases, many clustered near the mutation cluster region, as well as single or two base deletions in ~70% canine tumors of both subtypes. These observations indicate that like in the human, APC is also frequently altered in sporadic colorectal tumors in the dog and its alteration is an early event in canine colorectal tumorigenesis. Our study provides further evidence demonstrating the molecular similarity in pathogenesis between sporadic human and canine CRCs. This work, along with our previous copy number abnormality study, supports that sporadic canine CRCs are valid models of human CRCs at the molecular level.

  1. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment

    PubMed Central

    Cui, Yan; Guo, Gang

    2016-01-01

    The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome. PMID:27869779

  2. The potential for tumor suppressor gene therapy in head and neck cancer.

    PubMed

    Birkeland, Andrew C; Ludwig, Megan L; Spector, Matthew E; Brenner, J Chad

    2016-01-01

    Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer.

  3. The Potential for Tumor Suppressor Gene Therapy in Head and Neck Cancer

    PubMed Central

    Birkeland, Andrew C.; Ludwig, Megan L.; Spector, Matthew E.; Brenner, J. Chad

    2016-01-01

    Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer. PMID:26896601

  4. Functional evidence for a second tumor suppressor gene on human chromosome 17.

    PubMed Central

    Chen, P; Ellmore, N; Weissman, B E

    1994-01-01

    The development and progression of human tumors often involves inactivation of tumor suppressor gene function. Observations that specific chromosome deletions correlate with distinct groups of cancer suggest that some types of tumors may share common defective tumor suppressor genes. In support of this notion, our initial studies showed that four human carcinoma cell lines belong to the same complementation group for tumorigenic potential. In this investigation, we have extended these studies to six human soft tissue sarcoma cell lines. Our data showed that hybrid cells between a peripheral neuroepithelioma (PNET) cell line and normal human fibroblasts or HeLa cells were nontumorigenic. However, hybrid cells between the PNET cell line and five other soft tissue sarcoma cell lines remained highly tumorigenic, suggesting at least one common genetic defect in the control of tumorigenic potential in these cells. To determine the location of this common tumor suppressor gene, we examined biochemical and molecular polymorphic markers in matched pairs of tumorigenic and nontumorigenic hybrid cells between the PNET cell line and a normal human fibroblast. The data showed that loss of the fibroblast-derived chromosome 17 correlated with the conversion from nontumorigenic to tumorigenic cells. Transfer of two different chromosome 17s containing a mutant form of the p53 gene into the PNET cell line caused suppression of tumorigenic potential, implying the presence of a second tumor suppressor gene on chromosome 17. Images PMID:8264622

  5. Advances in the understanding of the Fanconi anemia tumor suppressor pathway.

    PubMed

    Pickering, Anna; Zhang, Jun; Panneerselvam, Jayabal; Fei, Peiwen

    2013-12-01

    Extremely high cancer incidence in Fanconi anemia (FA) patients has long suggested that the FA signaling pathway is a tumor suppressor pathway. Indeed, our recent findings, for the first time, indicate that the FA pathway plays a significant role in suppressing the development of non-FA human cancer. Also our studies on FA group D2 protein (FANCD2) have, among the first, documented the crosstalks between the FA and Rad6/Rad18 (HHR6) pathways upon DNA damage. In this review, we will discuss how our studies enhance the understanding of the FA tumor suppressor pathway.

  6. Is Rab25 a tumor promoter or suppressor--context dependency on RCP status?

    PubMed

    Tang, Bor Luen

    2010-08-01

    Conflicting reports in the literature suggest that Rab25 could either be a context dependent promoter or suppressor of tumorigenesis. We hypothesized that whether Rab25 acts as a promoter or suppressor in tumor progression depends on the expression status of its effector, the Rab coupling protein (RCP). An elevated expression of RCP resulting from genomic amplification may enhance Rab25's tumor progression activity. Elevation of Rab25 alone may sequester endogenous RCP, and attenuates its activating effect on other oncogenic products, such as mutant Ras.

  7. Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome 11P15.5

    DTIC Science & Technology

    1997-07-01

    4. Fults, D., Petronio, J., Noblett, B. D., Pedone, C. A. Chromosome 11p15 deletions in human malignant astrocytomas and primitive neuroectodermal ...AD _ GRANT NUMBER DAMDI7-94-J-4175 TITLE: Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome 11P15.5 PRINCIPAL INVESTIGATOR: Tracey...FUNDING NUMBERS Mapping of a Breast Carcinoma Tumor Suppressor Gene to Chromosome llP15.5 DAMD17-94-J-4175 6. AUTHOR(S) Tracey Moore, Ph.D. 7

  8. Identification of Tumor Suppressors and Oncogenes from Genomic and Epigenetic Features in Ovarian Cancer

    PubMed Central

    Wrzeszczynski, Kazimierz O.; Varadan, Vinay; Byrnes, James; Lum, Elena; Kamalakaran, Sitharthan; Levine, Douglas A.; Dimitrova, Nevenka; Zhang, Michael Q.; Lucito, Robert

    2011-01-01

    The identification of genetic and epigenetic alterations from primary tumor cells has become a common method to identify genes critical to the development and progression of cancer. We seek to identify those genetic and epigenetic aberrations that have the most impact on gene function within the tumor. First, we perform a bioinformatic analysis of copy number variation (CNV) and DNA methylation covering the genetic landscape of ovarian cancer tumor cells. We separately examined CNV and DNA methylation for 42 primary serous ovarian cancer samples using MOMA-ROMA assays and 379 tumor samples analyzed by The Cancer Genome Atlas. We have identified 346 genes with significant deletions or amplifications among the tumor samples. Utilizing associated gene expression data we predict 156 genes with altered copy number and correlated changes in expression. Among these genes CCNE1, POP4, UQCRB, PHF20L1 and C19orf2 were identified within both data sets. We were specifically interested in copy number variation as our base genomic property in the prediction of tumor suppressors and oncogenes in the altered ovarian tumor. We therefore identify changes in DNA methylation and expression for all amplified and deleted genes. We statistically define tumor suppressor and oncogenic features for these modalities and perform a correlation analysis with expression. We predicted 611 potential oncogenes and tumor suppressors candidates by integrating these data types. Genes with a strong correlation for methylation dependent expression changes exhibited at varying copy number aberrations include CDCA8, ATAD2, CDKN2A, RAB25, AURKA, BOP1 and EIF2C3. We provide copy number variation and DNA methylation analysis for over 11,500 individual genes covering the genetic landscape of ovarian cancer tumors. We show the extent of genomic and epigenetic alterations for known tumor suppressors and oncogenes and also use these defined features to identify potential ovarian cancer gene candidates. PMID

  9. AZU-1: A Candidate Breast Tumor Suppressor and Biomarker for Tumor Progression

    SciTech Connect

    Chen, Huei-Mei; Schmeichel, Karen L; Mian, I. Saira; Lelie`vre, Sophie; Petersen, Ole W; Bissell, Mina J

    2000-02-04

    To identify genes misregulated in the final stages of breast carcinogenesis, we performed differential display to compare the gene expression patterns of the human tumorigenic mammary epithelial cells, HMT-3522-T4-2, with those of their immediate premalignant progenitors, HMT-3522-S2. We identified a novel gene, called anti-zuai-1 (AZU-1), that was abundantly expressed in non- and premalignant cells and tissues but was appreciably reduced in breast tumor cell types and in primary tumors. The AZU-1 gene encodes an acidic 571-amino-acid protein containing at least two structurally distinct domains with potential protein-binding functions: an N-terminal serine and proline-rich domain with a predicted immunoglobulin-like fold and a C-terminal coiled-coil domain. In HMT-3522 cells, the bulk of AZU-1 protein resided in a detergent-extractable cytoplasmic pool and was present at much lower levels in tumorigenic T4-2 cells than in their nonmalignant counterparts. Reversion of the tumorigenic phenotype of T4-2 cells, by means described previously, was accompanied by the up-regulation of AZU-1. In addition, reexpression of AZU-1 in T4-2 cells, using viral vectors, was sufficient to reduce their malignant phenotype substantially, both in culture and in vivo. These results indicate that AZU-1 is a candidate breast tumor suppressor that may exert its effects by promoting correct tissue morphogenesis.

  10. Monocytic myeloid-derived suppressor cells as a potent suppressor of tumor immunity in non-small cell lung cancer

    PubMed Central

    Pogoda, Katarzyna; Pyszniak, Maria; Rybojad, Paweł; Tabarkiewicz, Jacek

    2016-01-01

    Immunotherapy is a promising therapeutic option for patients with non-small cell lung cancer (NSCLC) who do not qualify for surgery. In patients with advanced NSCLC, systemic immune suppression is frequently observed, therefore, researchers are investigating the tumor microenvironment for less invasive and more effective methods of treating lung cancer. Monocytic myeloid-derived suppressor cells (Mo-MDSCs) are potent suppressors of tumor immunity; therefore, this population may significantly impede the application of immunotherapy to treat cancer. The present study evaluated the distribution of Mo-MDSCs and monocytes/macrophages in the peripheral blood, lymph nodes and tumor tissue of patients with NSCLC. Furthermore, the profiles of cytokines produced by these cell populations, including interleukin (IL)-1β, IL-12/23p40, IL-10, transforming growth factor-β (TGF-β) and tumor necrosis factor (TNF), were compared. The cell populations and the expression of cytokines were assessed by flow cytometry after 4 h in culture with mitogens and Brefeldin A. Mo-MDSCs were more numerous than monocytes/macrophages in all tissues and their prevalence was highest in the peripheral blood; they expressed higher levels of TGF-β than monocytes/macrophages in all tissues and expression of TGF-β produced by Mo-MDSCs was higher in the blood than in lymph nodes and tumor tissues. A higher percentage of monocytes/macrophages was observed in lymph nodes and tumor tissues than in blood. CD14+HLA-DR+ cells also produced more IL-10 in lymph nodes than Mo-MDSCs and more IL-1β and TNF in all tissues. A higher prevalence of cluster of differentiation 14+ human leukocyte antigen-D related+ cells secreting IL-1β, TNF and IL-12/23p40 was observed in peripheral blood. Thus, the results of the current study support the statement that Mo-MDSCs and monocytes/macrophages participate in NSCLC induced immunosuppression, and is consistent with previous research into associations between the TGF

  11. Macrophages, Inflammation, and Tumor Suppressors: ARF, a New Player in the Game

    PubMed Central

    Través, Paqui G.; Luque, Alfonso; Hortelano, Sonsoles

    2012-01-01

    The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed. PMID:23316105

  12. Cyclophosphamide-facilitated adoptive immunotherapy of an established tumor depends on elimination of tumor-induced suppressor T cells

    PubMed Central

    1982-01-01

    On the basis of preceding studies showing that tumor-induced, T cell- mediated immunosuppression serves as an obstacle to adoptive immunotherapy of the Meth A fibrosarcoma, it was predicted that cyclophosphamide treatment of tumor bearers would remove this obstacle and allow passively transferred immune T cells to cause tumor regression. It was found that infusion of immune spleen cells alone had no effect on tumor growth, and cyclophosphamide alone caused a temporary halt in tumor progression. In contrast, combination therapy consisting of intravenous injection of 100 mg/kg of cyclophosphamide followed 1 h later by intravenous infusion of tumor-immune spleen cells caused small, as well as large tumors, to completely and permanently regress. Tumor regression caused by combination therapy was completely inhibited by intravenous infusion of splenic T cells from donors with established tumors, but not by spleen cells from normal donors. These suppressor T cells were eliminated from the spleen by treating the tumor-bearing donors with 100 mg/kg of cyclophosphamide. Immune T cells, in contrast, were resistant to this dose of cyclophosphamide. These results show that failure of intravenously-infused, tumor- sensitized T cells to cause regression of the Meth A fibrosarcoma growing in its syngeneic or semi-syngeneic host is caused by the presence of a tumor-induced population of cyclophosphamide-sensitive suppressor T cells. PMID:6460831

  13. Power of PTEN/AKT: Molecular switch between tumor suppressors and oncogenes

    PubMed Central

    XIE, YINGQIU; NAIZABEKOV, SANZHAR; CHEN, ZHANLIN; TOKAY, TURSONJAN

    2016-01-01

    An increasing amount of evidence has shown that tumor suppressors can become oncogenes, or vice versa, but the mechanism behind this is unclear. Recent findings have suggested that phosphatase and tensin homolog (PTEN) is one of the powerful switches for the conversion between tumor suppressors and oncogenes. PTEN regulates a number of cellular processes, including cell death and proliferation, through the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. Furthermore, a number of studies have suggested that PTEN deletions may alter various functions of certain tumor suppressor and oncogenic proteins. The aim of the present review was to analyze specific cases driven by PTEN loss/AKT activation, including aberrant signaling pathways and novel drug targets for clinical application in personalized medicine. The findings illustrate how PTEN loss and/or AKT activation switches MDM2-dependent p53 downregulation, and induces conversion between oncogene and tumor suppressor in enhancer of zeste homolog 2, BTB domain-containing 7A, alternative reading frame 2, p27 and breast cancer 1, early onset, through multiple mechanisms. This review highlights the genetic basis of complex drug targets and provides insights into the rationale of precision cancer therapy. PMID:27347153

  14. Regulation of The Tumor Suppressor Activity of P53 In Human Breast Cancer

    DTIC Science & Technology

    1999-09-01

    Lenglet, S., Moreau , V., Iggo, R., and Frehourg. T. Michael Datto and Xiao-Fan Wang (Duke University) for the p21 pro- (1998) Oncgene 16, 1369-1372...School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA Depending upon particular cellular conditions, the tumor suppressor protein p53

  15. Antiviral activity of tumor-suppressor pathways: clues from molecular piracy by KSHV.

    PubMed

    Moore, P S; Chang, Y

    1998-04-01

    A common feature of many tumor viruses is that they possess genes that produce specific proteins to inhibit major cellular tumor-suppressor pathways. Despite intensive studies, the reasons why these diverse and unrelated viruses have independently evolved oncogenes remains obscure. Kaposi-sarcoma-associated herpesvirus (KSHV or HHV8) has pirated a number of recognizable cellular genes that are key to cell survival and proliferation. In this review, we provide an overview of the known activities of these viral genes and show that many of these pirated proteins affect the same cellular pathways targeted by other, unrelated tumor viruses. We speculate that tumor-suppressor pathways are used by the cell as a primary defense against persistent virus infection, in addition to their well-known activity in regulating cell proliferation.

  16. Repression of the Androgen Receptor by WT1, a Tumor Suppressor Gene

    DTIC Science & Technology

    2001-09-01

    indications of the portions of this data which are subject to such limitations, shall be included on any reproduction hereof which includes any part of the...Cancer Research 21:1-10 (2001). Motoyoshi Tanaka, Gail C. Fraizer, Jorge De La Cerda , Richard Cristiano, Monica Liebert, H. Barton Grossman, Connexin... Cerda , J. , Diaz M., "Wilms’ Tumor Suppressor Gene WT1 Suppresses tumor formation by Prostate Cancer Cells" (Manuscript in Preparation). Presentations

  17. Tumor-derived lactate and myeloid-derived suppressor cells: Linking metabolism to cancer immunology.

    PubMed

    Husain, Zaheed; Seth, Pankaj; Sukhatme, Vikas P

    2013-11-01

    Many malignant cells produce increased amounts of lactate, which promotes the development of myeloid-derived suppressor cells (MDSCs). MDSCs, lactate, and a low pH in the tumor microenvironment inhibit the function of natural killer (NK) cells and T lymphocytes, hence allowing for disease progression. Ketogenic diets can deplete tumor-bearing animals from MDSCs and regulatory T cells, thereby improving their immunological profile.

  18. Tumor STAT1 transcription factor activity enhances breast tumor growth and immune suppression mediated by myeloid-derived suppressor cells.

    PubMed

    Hix, Laura M; Karavitis, John; Khan, Mohammad W; Shi, Yihui H; Khazaie, Khashayarsha; Zhang, Ming

    2013-04-26

    Previous studies had implicated the IFN-γ transcription factor signal transducer and activator of transcription 1 (STAT1) as a tumor suppressor. However, accumulating evidence has correlated increased STAT1 activation with increased tumor progression in multiple types of cancer, including breast cancer. Indeed, we present evidence that tumor up-regulation of STAT1 activity in human and mouse mammary tumors correlates with increasing disease progression to invasive carcinoma. A microarray analysis comparing low aggressive TM40D and highly aggressive TM40D-MB mouse mammary carcinoma cells revealed significantly higher STAT1 activity in the TM40D-MB cells. Ectopic overexpression of constitutively active STAT1 in TM40D cells promoted mobilization of myeloid-derived suppressor cells (MDSCs) and inhibition of antitumor T cells, resulting in aggressive tumor growth in tumor-transplanted, immunocompetent mice. Conversely, gene knockdown of STAT1 in the metastatic TM40D-MB cells reversed these events and attenuated tumor progression. Importantly, we demonstrate that in human breast cancer, the presence of tumor STAT1 activity and tumor-recruited CD33(+) myeloid cells correlates with increasing disease progression from ductal carcinoma in situ to invasive carcinoma. We conclude that STAT1 activity in breast cancer cells is responsible for shaping an immunosuppressive tumor microenvironment, and inhibiting STAT1 activity is a promising immune therapeutic approach.

  19. RBSP3 (HYA22) is a tumor suppressor gene implicated in major epithelial malignancies

    PubMed Central

    Kashuba, Vladimir I.; Li, Jingfeng; Wang, Fuli; Senchenko, Vera N.; Protopopov, Alexey; Malyukova, Alena; Kutsenko, Alexey S.; Kadyrova, Elena; Zabarovska, Veronika I.; Muravenko, Olga V.; Zelenin, Alexander V.; Kisselev, Lev L.; Kuzmin, Igor; Minna, John D.; Winberg, Gösta; Ernberg, Ingemar; Braga, Eleonora; Lerman, Michael I.; Klein, George; Zabarovsky, Eugene R.

    2004-01-01

    Chromosome 3p21.3 region is frequently (>90%) deleted in lung and other major human carcinomas. We subdivided 3p21.3 into LUCA and AP20 subregions and discovered frequent homozygous deletions (10-18%) in both subregions. This finding strongly implies that they harbor multiple tumor suppressor genes involved in the origin and/or development of major epithelial cancers. In this study, we performed an initial analysis of RBSP3/HYA22, a candidate tumor suppressor genes located in the AP20 region. Two sequence splice variants of RBSP3/HYA22 (A and B) were identified, and we provide evidence for their tumor suppressor function. By sequence analysis RBSP3/HYA22 belongs to a gene family of small C-terminal domain phosphatases that may control the RNA polymerase II transcription machinery. Expression of the gene was drastically (>20-fold) decreased in 11 of 12 analyzed carcinoma cell lines and in three of eight tumor biopsies. We report missense and nonsense mutations in tumors where RBSP3/HYA22 was expressed, growth suppression with regulated transgenes in culture, suppression of tumor formation in severe combined immunodeficient mice, and dephosphorylation of ppRB by RBSP3/HYA22, presumably leading to a block of the cell cycle at the G1/S boundary. PMID:15051889

  20. RSUME inhibits VHL and regulates its tumor suppressor function.

    PubMed

    Gerez, J; Tedesco, L; Bonfiglio, J J; Fuertes, M; Barontini, M; Silberstein, S; Wu, Y; Renner, U; Páez-Pereda, M; Holsboer, F; Stalla, G K; Arzt, E

    2015-09-10

    Somatic mutations or loss of von Hippel-Lindau (pVHL) happen in the majority of VHL disease tumors, which present a constitutively active Hypoxia Inducible Factor (HIF), essential for tumor growth. Recently described mechanisms for pVHL modulation shed light on the open question of the HIF/pVHL pathway regulation. The aim of the present study was to determine the molecular mechanism by which RSUME stabilizes HIFs, by studying RSUME effect on pVHL function and to determine the role of RSUME on pVHL-related tumor progression. We determined that RSUME sumoylates and physically interacts with pVHL and negatively regulates the assembly of the complex between pVHL, Elongins and Cullins (ECV), inhibiting HIF-1 and 2α ubiquitination and degradation. We found that RSUME is expressed in human VHL tumors (renal clear-cell carcinoma (RCC), pheochromocytoma and hemangioblastoma) and by overexpressing or silencing RSUME in a pVHL-HIF-oxygen-dependent degradation stability reporter assay, we determined that RSUME is necessary for the loss of function of type 2 pVHL mutants. The functional RSUME/pVHL interaction in VHL-related tumor progression was further confirmed using a xenograft assay in nude mice. RCC clones, in which RSUME was knocked down and express either pVHL wt or type 2 mutation, have an impaired tumor growth, as well as HIF-2α, vascular endothelial growth factor A and tumor vascularization diminution. This work shows a novel mechanism for VHL tumor progression and presents a new mechanism and factor for targeting tumor-related pathologies with pVHL/HIF altered function.

  1. RASSF10 is epigenetically silenced and functions as a tumor suppressor in gastric cancer

    SciTech Connect

    Wei, Ziran; Chen, Xia; Chen, Ji; Wang, Weimin; Xu, Xudong; Cai, Qingping

    2013-03-22

    Highlights: ► Epigenetic silencing of RASSF10 gene expression in GC cells. ► RASSF10 overexpression inhibits cell growth in vitro and in vivo. ► RASSF10 induces apoptosis in GC cells. ► RASSF10 inhibits Wnt/β-catenin signaling pathway. -- Abstract: Ras association domain family (RASSF) proteins are encoded by several tumor suppressor genes that are frequently silenced in human cancers. In this study, we investigated RASSF10 as a target of epigenetic inactivation and examined its functions as a tumor suppressor in gastric cancer. RASSF10 was silenced in six out of eight gastric cancer cell lines. Loss or downregulation of RASSF10 expression was associated with promoter hypermethylation, and could be restored by a demethylating agent. Overexpression of RASSF10 in gastric cancer cell lines (JRST, BGC823) suppressed cell growth and colony formation, and induced apoptosis, whereas RASSF10 depletion promoted cell growth. In xenograft animal experiments, RASSF10 overexpression effectively repressed tumor growth. Mechanistic investigations revealed that RASSF10 inhibited tumor growth by blocking activation of β-catenin and its downstream targets including c-Myc, cyclinD1, cyclinE1, peroxisome proliferator-activated receptor δ, transcription factor 4, transcription factor 1 and CD44. In conclusion, the results of this study provide insight into the role of RASSF10 as a novel functional tumor suppressor in gastric cancer through inhibition of the Wnt/β-catenin signaling pathway.

  2. CMTM5 exhibits tumor suppressor activity through promoter methylation in oral squamous cell carcinoma

    SciTech Connect

    Zhang, Heyu; Nan, Xu; Li, Xuefen; Chen, Yan; Zhang, Jianyun; Sun, Lisha; Han, Wenlin; Li, Tiejun

    2014-05-02

    Highlights: • Down-regulation of CMTM5 expression in OSCC tissues was found. • The promoter methylation status of CMTM5 was measured. • CMTM5-v1 inhibited cell proliferation and migration and induced apoptosis. • CMTM5 might act as a putative tumor suppressor gene in OSCC. - Abstract: Oral squamous cell carcinoma (OSCC) is one of the most common types of malignancies in the head and neck region. CKLF-like MARVEL transmembrane domain-containing member 5 (CMTM5) has been recently implicated as a tumor suppressor gene in several cancer types. Herein, we examined the expression and function of CMTM5 in oral squamous cell carcinoma. CMTM5 was down-regulated in oral squamous cell lines and tumor samples from patients with promoter methylation. Treatment with the demethylating agent 5-aza-2′-deoxycytidine restored CMTM5 expression. In the OSCC cell lines CAL27 and GNM, the ectopic expression of CMTM5-v1 strongly inhibited cell proliferation and migration and induced apoptosis. In addition, CMTM5-v1 inhibited tumor formation in vivo. Therefore, CMTM5 might act as a putative tumor suppressor gene through promoter methylation in oral squamous cell carcinoma.

  3. Cables1 is a tumor suppressor gene that regulates intestinal tumor progression in Apc(Min) mice.

    PubMed

    Arnason, Thomas; Pino, Maria S; Yilmaz, Omer; Kirley, Sandra D; Rueda, Bo R; Chung, Daniel C; Zukerberg, Lawrence R

    2013-07-01

    The transformation of colonic mucosal epithelium to adenocarcinoma requires progressive oncogene activation and tumor suppressor gene inactivation. Loss of chromosome 18q is common in colon cancer but not in precancerous adenomas. A few candidate tumor suppressor genes have been identified in this region, including CABLES1 at 18q11.2-12.1. This study investigates the role of CABLES1 in an in vivo mouse model of intestinal adenocarcinoma and in human colon cancer cell culture. Apc(Min/+) mice were crossed with mice harboring targeted inactivation of the Cables1 gene (Cables1(-/-)). The intestinal tumor burden and tumor expression of β-catenin and PCNA was compared in Cables1(+/+)Apc(Min/+) and Cables1(-/-)Apc(Min/+) mice. β-catenin activity in human colon cancer cells with CABLES1 inactivation and intestinal progenitor cell function in Cables1(-/-) mice were assayed in vitro. The mean number of small intestinal tumors per mouse was 3.1 ± 0.6 in Cables1(+/+)Apc(Min/+) mice, compared with 32.4 ± 3.5 in the Cables1(-/-)Apc(Min/+) mice (P < 0.0001). Fewer colonic tumors were observed in Cables1(+/+)Apc(Min/+) mice (mean 0.6 ± 0.1) compared with the Cables1(-/-)Apc(Min/+) mice (mean 1.3 ± 0.3, P = 0.01). Tumors from Cables1(-/-)Apc(Min/+) mice demonstrated increased nuclear expression of β-catenin and an increased number of PCNA-positive cells. In vitro studies revealed that CABLES1 deficiency increased β-catenin dependent transcription and increased intestinal progenitor cell activity. Loss of Cables1 enhances tumor progression in the Apc(Min/+) mouse model and activates the Wnt/β-catenin signaling pathway. Cables1 is a tumor suppressor gene on chromosome 18q in this in vivo mouse model and likely has a similar role in human colon cancer.

  4. Complement component 7 (C7), a potential tumor suppressor, is correlated with tumor progression and prognosis

    PubMed Central

    Pan, Xiaodan; Chen, Kaiyan; Zhang, Nan; Jin, Jiaoyue; Wu, Junzhou; Feng, Jianguo; Yu, Herbert; Jin, Hongchuan; Su, Dan

    2016-01-01

    Our previous study found copy number variation of chromosome fragment 5p13.1-13.3 might involve in the progression of ovarian cancer. In the current study, the alteration was validated and complement component 7 (C7), located on 5p13.1, was identified. To further explore the clinical value of C7 in tumors, 156 malignant, 22 borderline, 33 benign and 24 normal ovarian tissues, as well as 173 non-small cell lung cancer (NSCLC) tissues along with corresponding adjacent and normal tissues from the tissue bank of Zhejiang Cancer Hospital were collected. The expression of C7 was analyzed using reverse transcriptase quantitative polymerase chain reaction. As a result, the C7 expression displayed a gradual downward trend in normal, benign, borderline and malignant ovarian tissues, and the decreased expression of C7 was correlative to poor differentiation in patients with ovarian cancer. Interestingly, a similar change of expression of C7 was found in normal, adjacent and malignant tissues in patients with NSCLC, and low expression of C7 was associated with worse grade and advanced clinical stage. Both results from this cohort and the public database indicated that NSCLC patients with low expression of C7 had a worse outcome. Furthermore, multivariate cox regression analysis showed NSCLC patients with low C7 had a 3.09 or 5.65-fold higher risk for relapse or death than those with high C7 respectively, suggesting C7 was an independent prognostic predictor for prognoses of patients with NSCLC. Additionally, overexpression of C7 inhibited colony formation of NSCLC cells, which hints C7 might be a potential tumor suppressor. PMID:27852032

  5. Role of the ARF Tumor Suppressor in Prostate Cancer

    DTIC Science & Technology

    2010-08-01

    literature. We asked Dr. Jeff Arbeit in the department of Surgery here at Washington University for his expertise in mouse prostate tumor development...18070929 6. Lu, Z.H., Wright, J.D., Belt, B., Cardiff, R.D. & Arbeit , J.M. Hypoxia-inducible factor-1 facilitates cervical cancer progression in human

  6. Estrogen receptor beta, a possible tumor suppressor involved in ovarian carcinogenesis

    PubMed Central

    Lazennec, Gwendal

    2006-01-01

    Ovarian cancer is one of the leading cause of death from gynecological tumors in women. Several lines of evidence suggest that estrogens may play an important role in ovarian carcinogenesis, through their receptors, ERα and ERβ. Interestingly, malignant ovarian tumors originating from epithelial surface constitute about 90% of ovarian cancers and expressed low levels of ERβ, compared to normal tissues. In addition, restoration of ERβ in ovarian cancer cells, leads to strong inhibition of their proliferation and invasion, while apoptosis is enhanced. In this manuscript, recent data suggesting a possible tumor-suppressor role for ERβ in ovarian carcinogenesis are discussed. PMID:16399219

  7. Myeloid-derived suppressor cell role in tumor-related inflammation.

    PubMed

    Dolcetti, Luigi; Marigo, Ilaria; Mantelli, Barbara; Peranzoni, Elisa; Zanovello, Paola; Bronte, Vincenzo

    2008-08-28

    Chronic inflammatory state can create a proper environment for neoplastic onset and sustain cancer growth. The inflammatory state that arises at the tumor edge could contribute to immune escape phenomena in many ways. Myeloid-derived suppressor cells (MDSCs), a cell population that contributes to tumor escape, immune tolerance, and suppression, respond to a variety of pro-inflammatory and anti-inflammatory stimuli, which drive their recruitment and activation. Understanding how the inflammatory milieu favours tumor escape through the accumulation of MDSCs could be very useful to improve the efficacy of cancer immunotherapy.

  8. The retinoblastoma tumor suppressor modulates DNA repair and radioresponsiveness

    PubMed Central

    Thangavel, Chellappagounder; Liu, Yi; O’Neill, Raymond; Sharma, Ankur; McMahon, Steve B.; Mellert, Hestia; Addya, Sankar; Ertel, Adam; Birbe, Ruth; Fortina, Paolo; Dicker, Adam P; Knudsen, Karen E; Den, Robert B

    2014-01-01

    Purpose Perturbations in the RB pathway are overrepresented in advanced prostate cancer; RB loss promotes bypass of first line hormone therapy. Conversely, preliminary studies suggested that RB-deficient tumors may become sensitized to a subset of DNA damaging agents. Here, the molecular and in vivo consequence of RB status was analyzed in models of clinical relevance. Experimental Design Experimental work was performed with multiple isogenic prostate cancer cell lines (hormone sensitive: LNCaP and LAPC4 cells and hormone resistant C42, 22Rv1 cells; stable knockdown of RB using shRNA). Multiple mechanisms were interrogated including cell cycle, apoptosis, and DNA damage repair. Transcriptome analysis was performed, validated, and mechanisms discerned. Cell survival was measured using clonogenic cell survival assay and in vivo analysis was performed in nude mice with human derived tumor xenografts. Results Loss of RB enhanced the radioresponsiveness of both hormone sensitive and castrate resistant prostate cancer. Hypersensitivity to ionizing radiation was not mediated by cell cycle or p53. RB loss led to alteration in DNA damage repair and activation of the NFκB pathway and subsequent cellular apoptosis through PLK3. In vivo xenografts of RB deficient tumors exhibited diminished tumor mass, lower PSA kinetics and decreased tumor growth after treatment with ionizing radiation (p<0.05). Conclusions Loss of RB confers increased radiosensitivity in prostate cancer. This hypersensitization was mediated by alterations in apoptotic signaling. Combined, these not only provide insight into the molecular consequence of RB loss, but also credential RB status as a putative biomarker for predicting response to radiation therapy. PMID:25165096

  9. Tumor-induced tolerance and immune suppression by myeloid derived suppressor cells.

    PubMed

    Marigo, Ilaria; Dolcetti, Luigi; Serafini, Paolo; Zanovello, Paola; Bronte, Vincenzo

    2008-04-01

    Emerging evidence indicates that the Achilles' heel of cancer immunotherapies is often the complex interplay of tumor-derived factors and deviant host properties, which involve a wide range of immune elements in the lymphoid and myeloid compartments. Regulatory lymphocytes, tumor-conditioned myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages, and dysfunctional and immature dendritic cells take part in a complex immunoregulatory network. Despite the fact that some mechanisms governing tumor-induced immune tolerance and suppression are starting to be better understood and their complexity dissected, little is known about the diachronic picture of immune tolerance. Based on observations of MDSCs, we present a time-structured and topologically consistent idea of tumor-dependent tolerance progression in tumor-bearing hosts.

  10. Cyclin D1 down-regulation is essential for DBC2's tumor suppressor function

    SciTech Connect

    Yoshihara, Takashi; Collado, Denise; Hamaguchi, Masaaki . E-mail: hamaguchi@fordham.edu

    2007-07-13

    The expression of tumor suppressor gene DBC2 causes certain breast cancer cells to stop growing [M. Hamaguchi, J.L. Meth, C. Von Klitzing, W. Wei, D. Esposito, L. Rodgers, T. Walsh, P. Welcsh, M.C. King, M.H. Wigler, DBC2, a candidate for a tumor suppressor gene involved in breast cancer, Proc. Natl. Acad. Sci. USA 99 (2002) 13647-13652]. Recently, DBC2 was found to participate in diverse cellular functions such as protein transport, cytoskeleton regulation, apoptosis, and cell cycle control [V. Siripurapu, J.L. Meth, N. Kobayashi, M. Hamaguchi, DBC2 significantly influences cell cycle, apoptosis, cytoskeleton, and membrane trafficking pathways. J. Mol. Biol. 346 (2005) 83-89]. Its tumor suppression mechanism, however, remains unclear. In this paper, we demonstrate that DBC2 suppresses breast cancer proliferation through down-regulation of Cyclin D1 (CCND1). Additionally, the constitutional overexpression of CCND1 prevented the negative impact of DBC2 expression on their growth. Under a CCND1 promoter, the expression of CCNE1 exhibited the same protective effect. Our results indicate that the down-regulation of CCND1 is an essential step for DBC2's growth suppression of cancer cells. We believe that this discovery contributes to a better understanding of DBC2's tumor suppressor function.

  11. Characterization of a set of tumor suppressor microRNAs in T cell acute lymphoblastic leukemia

    PubMed Central

    Sanghvi, Viraj R.; Mavrakis, Konstantinos J.; Van der Meulen, Joni; Boice, Michael; Wolfe, Andrew L.; Carty, Mark; Mohan, Prathibha; Rondou, Pieter; Socci, Nicholas D.; Benoit, Yves; Taghon, Tom; Van Vlierberghe, Pieter; Leslie, Christina S.; Speleman, Frank; Wendel, Hans-Guido

    2015-01-01

    The posttranscriptional control of gene expression by microRNAs (miRNAs) is highly redundant, and compensatory effects limit the consequences of the inactivation of individual miRNAs. This implies that only a few miRNAs can function as effective tumor suppressors. It is also the basis of our strategy to define functionally relevant miRNA target genes that are not under redundant control by other miRNAs. We identified a functionally interconnected group of miRNAs that exhibited a reduced abundance in leukemia cells from patients with T cell acute lymphoblastic leukemia (T-ALL). To pinpoint relevant target genes, we applied a machine learning approach to eliminate genes that were subject to redundant miRNA-mediated control and to identify those genes that were exclusively targeted by tumor-suppressive miRNAs. This strategy revealed the convergence of a small group of tumor suppressor miRNAs on the Myb oncogene, as well as their effects on HBP1, which encodes a transcription factor. The expression of both genes was increased in T-ALL patient samples, and each gene promoted the progression of T-ALL in mice. Hence, our systematic analysis of tumor suppressor miRNA action identified a widespread mechanism of oncogene activation in T-ALL. PMID:25406379

  12. Complement inhibitor CSMD1 acts as tumor suppressor in human breast cancer

    PubMed Central

    Escudero-Esparza, Astrid; Okroj, Marcin; Owen, Sioned; Jirström, Karin; Orimo, Akira; Jiang, Wen G.; Pietras, Kristian; Blom, Anna M.

    2016-01-01

    Human CUB and Sushi multiple domains 1 (CSMD1) is a membrane-bound complement inhibitor suggested to act as a putative tumor suppressor gene, since allelic loss of this region encompassing 8p23 including CSMD1 characterizes various malignancies. Here, we assessed the role of CSMD1 as a tumor suppressor gene in the development of breast cancer in vitro and in vivo. We found that human breast tumor tissues expressed CSMD1 at lower levels compared to that in normal mammary tissues. The decreased expression of CSMD1 was linked to a shorter overall survival of breast cancer patients. We also revealed that expression of CSMD1 in human breast cancer cells BT-20 and MDA-MB-231 significantly inhibited their malignant phenotypes, including migration, adhesion and invasion. Conversely, stable silencing of CSMD1 expression in T47D cells enhanced cancer cell migratory, adherent and clonogenic abilities. Moreover, expression of CSMD1 in the highly invasive MDA-MB-231 cells diminished their signaling potential as well as their stem cell-like properties as assessed by measurement of aldehyde dehydrogenase activity. In a xenograft model, expression of CSMD1 blocked the ability of cancer cells to metastasize to secondary sites in vivo, likely via inhibiting local invasion but not the extravasation into distant tissues. Taken together, these findings demonstrate the role of CSMD1 as a tumor suppressor gene in breast cancer. PMID:27764775

  13. Isolation of Breast Tumor Suppressor Genes from Chromosome 11p

    DTIC Science & Technology

    2001-09-01

    at chromosome crucial role in urogenital development (Pelletier et al., llp15 has also been described in Wilms tumors but thus 1991). However...Atkins L and Riccardi VM. (1979). Nowak NJ, Evans G, Stanbridge EJ, de Jong P, Shows TB , Cytogenet. Cell Genet., 24, 185-192. Weissman BE and Higgins MJ...Singh-Kahlon P, Weksberg R, Squire J, Grundy P, Coppes MJ and Haber D. (1995). Hematology/ Shows TB and Higgins MJ. (1994). Genes Chromosomes Oncology

  14. The vitamin D receptor: a tumor suppressor in skin.

    PubMed

    Bikle, Daniel D

    2014-01-01

    Cutaneous malignancies including melanomas and non melanoma skin cancers (NMSC) are the most common types of cancer, occurring at a rate of over 1 million per year in the United States. The major cell in the epidermis, the keratinocyte, not only produces vitamin D but contains the enzymatic machinery to metabolize vitamin D to its active metabolite, 1,25(OH)2D, and expresses the receptor for this metabolite, the vitamin D receptor (VDR), allowing the cell to respond to the 1,25(OH)2D that it produces. In vitro, 1,25(OH)2D stimulates the differentiation and inhibits the proliferation of these cells and so would be expected to be tumor suppressive. However, epidemiologic evidence demonstrating a negative relationship between circulating levels of the substrate for CYP27B1, 25OHD, and the incidence of these malignancies is mixed, raising the question whether vitamin D is protective in the in vivo setting. UV radiation (UV), both UVB and UVA, as occurs with sunlight exposure is generally regarded as causal for these malignancies, but UVB is also required for vitamin D synthesis in the skin. This complicates conclusions reached from epidemiologic studies in that UVB is associated with higher 25OHD levels as well as increased incidence of cutaneous malignancies. Based on our own data and that reported in the literature we hypothesize that vitamin D signaling in the skin suppresses UVR induced epidermal tumor formation. In this chapter we will first discuss recent data regarding potential mechanisms by which vitamin D signaling suppresses tumor formation, then focus on three general mechanisms that mediate tumor suppression by VDR in the skin: inhibition of proliferation and stimulation of differentiation, immune regulation, and stimulation of DNA damage repair (DDR).

  15. The vertebrate Hef ortholog is a component of the Fanconi anemia tumor-suppressor pathway.

    PubMed

    Mosedale, Georgina; Niedzwiedz, Wojciech; Alpi, Arno; Perrina, Franco; Pereira-Leal, Jose B; Johnson, Mark; Langevin, Frederic; Pace, Paul; Patel, Ketan J

    2005-09-01

    The helicase-associated endonuclease for fork-structured DNA (Hef) is an archaeabacterial protein that processes blocked replication forks. Here we have isolated the vertebrate Hef ortholog and investigated its molecular function. Disruption of this gene in chicken DT40 cells results in genomic instability and sensitivity to DNA cross-links. The similarity of this phenotype to that of cells lacking the Fanconi anemia-related (FA) tumor-suppressor genes led us to investigate whether Hef functions in this pathway. Indeed, we found a genetic interaction between the FANCC and Hef genes. In addition, Hef is a component of the FA nuclear protein complex that facilitates its DNA damage-inducible chromatin localization and the monoubiquitination of the FA protein FANCD2. Notably, Hef interacts directly with DNA structures that are intermediates in DNA replication. This discovery sheds light on the origins, regulation and molecular function of the FA tumor-suppressor pathway in the maintenance of genome stability.

  16. Targeted ablation of the WW domain-containing oxidoreductase tumor suppressor leads to impaired steroidogenesis.

    PubMed

    Aqeilan, Rami I; Hagan, John P; de Bruin, Alain; Rawahneh, Maysoon; Salah, Zaidoun; Gaudio, Eugenio; Siddiqui, Hasan; Volinia, Stefano; Alder, Hansjuerg; Lian, Jane B; Stein, Gary S; Croce, Carlo M

    2009-03-01

    The WW domain-containing oxidoreductase (WWOX) gene encodes a 46-kDa tumor suppressor. The Wwox protein contains two N-terminal WW domains that interact with several transcriptional activators containing proline-tyrosine motifs and a central short-chain dehydrogenase/reductase domain that has been suggested to play a role in steroid metabolism. Recently, we have shown that targeted deletion of the Wwox gene in mice leads to postnatal lethality and defects in bone growth. Here, we report that Wwox-deficient mice display impaired steroidogenesis. Mutant homozygous mice are born with gonadal abnormalities, including failure of Leydig cell development in testis and reduced theca cell proliferation in ovary. Furthermore, Wwox(-/-) mice displayed impaired gene expression of key steroidogenesis enzymes. Affymetrix microarray gene analysis revealed differentially expressed related genes in steroidogenesis in knockout mice testis and ovary as compared with control mice. These results demonstrate the essential requirement for the Wwox tumor suppressor in proper steroidogenesis.

  17. Functional association between Wwox tumor suppressor protein and p73, a p53 homolog.

    PubMed

    Aqeilan, Rami I; Pekarsky, Yuri; Herrero, Juan J; Palamarchuk, Alexey; Letofsky, Jean; Druck, Teresa; Trapasso, Francesco; Han, Shuang-Yin; Melino, Gerry; Huebner, Kay; Croce, Carlo M

    2004-03-30

    The WWOX gene is a recently cloned tumor suppressor gene that spans the FRA16D fragile region. Wwox protein contains two WW domains that are generally known to mediate protein-protein interaction. Here we show that Wwox physically interacts via its first WW domain with the p53 homolog, p73. The tyrosine kinase, Src, phosphorylates Wwox at tyrosine 33 in the first WW domain and enhances its binding to p73. Our results further demonstrate that Wwox expression triggers redistribution of nuclear p73 to the cytoplasm and, hence, suppresses its transcriptional activity. In addition, we show that cytoplasmic p73 contributes to the proapoptotic activity of Wwox. Our findings reveal a functional cross-talk between p73 and Wwox tumor suppressor protein.

  18. MLL3 is a haploinsufficient 7q tumor suppressor in acute myeloid leukemia.

    PubMed

    Chen, Chong; Liu, Yu; Rappaport, Amy R; Kitzing, Thomas; Schultz, Nikolaus; Zhao, Zhen; Shroff, Aditya S; Dickins, Ross A; Vakoc, Christopher R; Bradner, James E; Stock, Wendy; LeBeau, Michelle M; Shannon, Kevin M; Kogan, Scott; Zuber, Johannes; Lowe, Scott W

    2014-05-12

    Recurring deletions of chromosome 7 and 7q [-7/del(7q)] occur in myelodysplastic syndromes and acute myeloid leukemia (AML) and are associated with poor prognosis. However, the identity of functionally relevant tumor suppressors on 7q remains unclear. Using RNAi and CRISPR/Cas9 approaches, we show that an ∼50% reduction in gene dosage of the mixed lineage leukemia 3 (MLL3) gene, located on 7q36.1, cooperates with other events occurring in -7/del(7q) AMLs to promote leukemogenesis. Mll3 suppression impairs the differentiation of HSPC. Interestingly, Mll3-suppressed leukemias, like human -7/del(7q) AMLs, are refractory to conventional chemotherapy but sensitive to the BET inhibitor JQ1. Thus, our mouse model functionally validates MLL3 as a haploinsufficient 7q tumor suppressor and suggests a therapeutic option for this aggressive disease.

  19. Phosphorylation of the tumor suppressor CYLD by the breast cancer oncogene IKKε promotes cell transformation

    PubMed Central

    Hutti, Jessica E.; Shen, Rhine R.; Abbott, Derek W.; Zhou, Alicia Y.; Sprott, Kam M.; Asara, John M.; Hahn, William C.; Cantley, Lewis C.

    2009-01-01

    Summary The non-canonical IKK family member IKKε is essential for regulating anti-viral signaling pathways and is a recently-discovered breast cancer oncoprotein. Although several IKKε targets have been described, direct IKKε substrates necessary for regulating cell transformation have not been identified. Here, we performed a screen for putative IKKε substrates using an unbiased proteomic and bioinformatic approach. Using a positional scanning peptide library assay we determined the optimal phosphorylation motif for IKKε and used bioinformatic approaches to predict IKKε substrates. Of these potential substrates, serine 418 of the tumor suppressor CYLD was identified as a likely site of IKKε phosphorylation. We confirmed that CYLD is directly phosphorylated by IKKε, and that IKKε phosphorylates serine 418 in vivo. Phosphorylation of CYLD at serine 418 decreases its deubiquitinase activity and is necessary for IKKε-driven transformation. Together, these observations define IKKε and CYLD as an oncogene-tumor suppressor network that participates in tumorigenesis. PMID:19481526

  20. Nutrient restriction enhances the proliferative potential of cells lacking the tumor suppressor PTEN in mitotic tissues

    PubMed Central

    Nowak, Katarzyna; Seisenbacher, Gerhard; Hafen, Ernst; Stocker, Hugo

    2013-01-01

    How single cells in a mitotic tissue progressively acquire hallmarks of cancer is poorly understood. We exploited mitotic recombination in developing Drosophila imaginal tissues to analyze the behavior of cells devoid of the tumor suppressor PTEN, a negative regulator of PI3K signaling, under varying nutritional conditions. Cells lacking PTEN strongly overproliferated specifically in nutrient restricted larvae. Although the PTEN mutant cells were sensitive to starvation, they successfully competed with neighboring cells by autonomous and non-autonomous mechanisms distinct from cell competition. The overgrowth was strictly dependent on the activity of the downstream components Akt/PKB and TORC1, and a reduction in amino acid uptake by reducing the levels of the amino acid transporter Slimfast caused clones of PTEN mutant cells to collapse. Our findings demonstrate how limiting nutritional conditions impact on cells lacking the tumor suppressor PTEN to cause hyperplastic overgrowth. DOI: http://dx.doi.org/10.7554/eLife.00380.001 PMID:23853709

  1. Functions of the Tumor Suppressors p53 and Rb in Actin Cytoskeleton Remodeling

    PubMed Central

    Ebata, Takahiro; Hirata, Hiroaki

    2016-01-01

    Mechanical microenvironments, such as extracellular matrix stiffness and strain, have crucial roles in cancer progression. Cells sense their microenvironments with mechanosensing biomolecules, which is accompanied by the modulation of actin cytoskeleton structures, and the signals are subsequently transduced downstream as biochemical signals. The tumor suppressors p53 and retinoblastoma protein (Rb) are known to prevent cancer progression. The p53 and Rb signaling pathways are disrupted in many types of cancers. Here, we review recent findings about the roles of these tumor suppressors in the regulation of mechanosensing biomolecules and the actin cytoskeleton. We further discuss how dysfunction in the p53- and/or Rb-mediated mechanosignaling pathways is potentially involved in cancer progression. These pathways might provide good targets for developing anticancer therapies. PMID:28078303

  2. Tumor Suppressor WWOX and p53 Alterations and Drug Resistance in Glioblastomas

    PubMed Central

    Chiang, Ming-Fu; Chou, Pei-Yi; Wang, Wan-Jen; Sze, Chun-I; Chang, Nan-Shan

    2013-01-01

    Tumor suppressor p53 are frequently mutated in glioblastomas (GBMs) and appears to contribute, in part, to resistance to temozolomide (TMZ) and therapeutic drugs. WW domain-containing oxidoreductase WWOX (FOR or WOX1) is a proapoptotic protein and is considered as a tumor suppressor. Loss of WWOX gene expression is frequently seen in malignant cancer cells due to promoter hypermethylation, genetic alterations, and translational blockade. Intriguingly, ectopic expression of wild type WWOX preferentially induces apoptosis in human glioblastoma cells harboring mutant p53. WWOX is known to physically bind and stabilize wild type p53. Here, we provide an overview for the updated knowledge in p53 and WWOX, and postulate potential scenarios that wild type and mutant p53, or isoforms, modulate the apoptotic function of WWOX. We propose that triggering WWOX activation by therapeutic drugs under p53 functional deficiency is needed to overcome TMZ resistance and induce GBM cell death. PMID:23459853

  3. Role of the Rb and p53 Tumor Suppressor Pathways in Mammary Tumorigenesis

    DTIC Science & Technology

    2012-09-01

    kinase screen and off-patent drug screen) REPORTABLE OUTCOMES Jones, Robert., Jiang, Zhe ., Deng, Tao., Schimmer, AD., Moffat, J and...Robert., Jiang, Zhe ., Deng, Tao., Schimmer, AD., Moffat, J and Zacksenhaus, E. Role of the RB and p53 tumor suppressor pathways in mammary tumorigenesis...CDMRP 2011 Era of Hope Conference Jiang Z, Jones R, Liu JC, Deng T, Robinson T, Chung PE, Wang S, Herschkowitz Jl, Egan SE, Perou CM

  4. Isolation of a Breast Cancer Tumor Suppressor Gene from Chromosome 3p

    DTIC Science & Technology

    1995-10-01

    regions) of 3p that most consistently undergo LOH in breast cancer and to further narrow the critical region in order to facilitate molecular cloning of...tumorigenesis. In the identification and molecular cloning of tumor suppressor genes, homozygous deletions have played a very major role in directing gene...narrow the critical region in order to facilitate molecular cloning of the disease gene. Fluorescence in situ hybridization will be employed as an

  5. Inflammation in Prostate Carcinogenesis: Role of the Tumor Suppressor Par-4

    DTIC Science & Technology

    2012-09-01

    which they coordinate with each other to form an intricate regula- tory network to protect against tumorigenesis. The Tumor Suppressor Par-4 at the...that integrates signals to coordinate molecular events that protect cells against tumorigenesis. Understanding the cross talks among each compo- nent...with the atypical isoforms of protein kinase C. Cell. 1996;86(5):777-86. 8. Sells SF, Wood DP, Jr., Joshi-Barve SS, Muthukumar S, Jacob RJ, Crist SA

  6. Identification of Novel Candidate Tumor Suppressor Genes Using C. elegans as a Model.

    DTIC Science & Technology

    1997-12-01

    Breast Cancer, Tumor Suppressors, Growth Factor Receptors, Model System, Molecular Cloning , Proto-Oncogenes, Genetic Analysis 15. NUMBER OF PAGES 26...its molecular cloning in any case since it represents a new locus. sy542 is being analyzed now to determine if it is worthy of pursuit. rok-2(sy317...allow its molecular cloning this year, rot-1 appears to act downstream oflin-25 as indicated by its suppression oflin-25 null mutation (Table 6

  7. Identification of Fat4 as a candidate tumor suppressor gene in breast cancers

    PubMed Central

    Qi, Chao; Zhu, Yiwei Tony; Hu, Liping; Zhu, Yi-Jun

    2009-01-01

    Fat, a candidate tumor suppressor in drosophila, is a component of Hippo signaling pathway involved in controlling organ size. We found that a ~3Mbp deletion in mouse chromosome 3 caused tumorigenesis of a non-tumorigenic mammary epithelial cell line. The expression of Fat4 gene, one member of the Fat family, in the deleted region was inactivated, which resulted from promoter methylation of another Fat4 allele following the deletion of one Fat4 allele. Re-expression of Fat4 in Fat4-deficient tumor cells suppressed the tumorigenecity while suppression of Fat4 expression in the non-tumorigenic mammary epithelial cell line induced tumorigenesis. We also found that Fat4 expression was lost in a large fraction of human breast tumor cell lines and primary tumors. Loss of Fat4 expression in breast tumors was associated with human Fat4 promoter methylation. Together, these findings suggest that Fat4 is a strong candidate for a breast tumor suppressor gene. PMID:19048595

  8. Proline oxidase functions as a mitochondrial tumor suppressor in human cancers

    PubMed Central

    Liu, Yongmin; Borchert, Gregory L.; Donald, Steve; Diwan, Bhalchandra; Anver, Miriam; Phang, James M.

    2009-01-01

    Tumor metabolism and bioenergetics have become important topics for cancer research and are promising targets for anticancer therapy. Although glucose serves as the main source of energy, proline, an alternative substrate, is important, especially during nutrient stress. Proline oxidase (POX), catalyzing the first step in proline catabolism, is induced by p53 and can regulate cell survival as well as mediate programmed cell death. In a mouse xenograft tumor model, we found that POX greatly reduced tumor formation by causing G2 cell cycle arrest. Furthermore, immunohistochemical staining showed decreased POX expression in tumor tissues. Importantly, HIF-1α signaling was impaired with POX expression due to the increased production of α-ketoglutarate, a critical substrate for prolyl hydroxylation and degradation of HIF-1α. Combined with previous in vitro findings and reported clinical genetic associations, these new findings lead us to propose POX as a mitochondrial tumor suppressor and a potential target for cancer therapy. PMID:19654292

  9. KLF10, transforming growth factor-{beta}-inducible early gene 1, acts as a tumor suppressor

    SciTech Connect

    Song, Ki-Duk; Kim, Duk-Jung; Lee, Jong Eun; Yun, Cheol-Heui; Lee, Woon Kyu

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer KLF10{sup -/-} mice exhibited accelerated papilloma development after DMBA/TPA treatment. Black-Right-Pointing-Pointer KLF10{sup -/-} keratinocytes showed increased proliferation and apoptosis. Black-Right-Pointing-Pointer KLF10{sup -/-} MEFs yielded more colonies than wild-type one with H-Ras transfection. Black-Right-Pointing-Pointer KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription. Black-Right-Pointing-Pointer KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription. -- Abstract: Krueppel-like factor 10 (KLF10) has been suggested to be a putative tumor suppressor. In the present study, we generated KLF10 deficient mice to explore this hypothesis in vivo. KLF10 deficient mice exhibited increased predisposition to skin tumorigenesis and markedly accelerated papilloma development after DMBA/TPA treatment. On the other hand, KLF10 deficient keratinocytes showed increased proliferation and apoptosis. In colony formation assays after oncogenic H-Ras transfection, KLF10 deficient mouse embryonic fibroblasts (MEFs) yielded more colonies than wild-type MEFs. Furthermore, KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription, which was independent of p53 and Sp1 binding sites in p21{sup WAF1/CIP1} promoter. This study demonstrates that KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription.

  10. Tumor suppressor WWOX regulates glucose metabolism via HIF1α modulation

    PubMed Central

    Abu-Remaileh, M; Aqeilan, R I

    2014-01-01

    The WW domain-containing oxidoreductase (WWOX) encodes a tumor suppressor that is frequently lost in many cancer types. Wwox-deficient mice develop normally but succumb to a lethal hypoglycemia early in life. Here, we identify WWOX as a tumor suppressor with emerging role in regulation of aerobic glycolysis. WWOX controls glycolytic genes' expression through hypoxia-inducible transcription factor 1α (HIF1α) regulation. Specifically, WWOX, via its first WW domain, physically interacts with HIF1α and modulates its levels and transactivation function. Consistent with this notion, Wwox-deficient cells exhibited increased HIF1α levels and activity and displayed increased glucose uptake. Remarkably, WWOX deficiency is associated with enhanced glycolysis and diminished mitochondrial respiration, conditions resembling the ‘Warburg effect'. Furthermore, Wwox-deficient cells are more tumorigenic and display increased levels of GLUT1 in vivo. Finally, WWOX expression is inversely correlated with GLUT1 levels in breast cancer samples highlighting WWOX as a modulator of cancer metabolism. Our studies uncover an unforeseen role for the tumor-suppressor WWOX in cancer metabolism. PMID:25012504

  11. Tumor suppressor WWOX regulates glucose metabolism via HIF1α modulation.

    PubMed

    Abu-Remaileh, M; Aqeilan, R I

    2014-11-01

    The WW domain-containing oxidoreductase (WWOX) encodes a tumor suppressor that is frequently lost in many cancer types. Wwox-deficient mice develop normally but succumb to a lethal hypoglycemia early in life. Here, we identify WWOX as a tumor suppressor with emerging role in regulation of aerobic glycolysis. WWOX controls glycolytic genes' expression through hypoxia-inducible transcription factor 1α (HIF1α) regulation. Specifically, WWOX, via its first WW domain, physically interacts with HIF1α and modulates its levels and transactivation function. Consistent with this notion, Wwox-deficient cells exhibited increased HIF1α levels and activity and displayed increased glucose uptake. Remarkably, WWOX deficiency is associated with enhanced glycolysis and diminished mitochondrial respiration, conditions resembling the 'Warburg effect'. Furthermore, Wwox-deficient cells are more tumorigenic and display increased levels of GLUT1 in vivo. Finally, WWOX expression is inversely correlated with GLUT1 levels in breast cancer samples highlighting WWOX as a modulator of cancer metabolism. Our studies uncover an unforeseen role for the tumor-suppressor WWOX in cancer metabolism.

  12. FAT4 functions as a tumor suppressor in triple-negative breast cancer.

    PubMed

    Hou, Lingmi; Chen, Maoshan; Zhao, Xiaobo; Li, Jingdong; Deng, Shishan; Hu, Jiani; Yang, Hongwei; Jiang, Jun

    2016-11-28

    Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is often associated with biologic behavior with frequent distant metastasis. FAT tumor suppressor homolog 4 (FAT4), a cadherin-related protein, is involved in a variety of biological processes as a tumor suppressor; however, the role of FAT4 in TNBC is still unclear. The aim of our study was to identify the role of FAT4 in TNBC and examine the underlying molecular mechanisms. The expression of FAT4 was evaluated by immunohistochemistry, western blotting, and qRT-PCR in a series of TNBC tissues. The effects of FAT4 on the ability of cell proliferation, migration, and invasion were assessed by MTT assay and migration and invasion assays. We demonstrated that the repression of FAT4 by shRNA could promote TNBC progression. Taken together, our findings provide evidence for a role of the FAT4 cluster as a tumor suppressor in TNBC patients and may serve as potential novel targets for the treatment of TNBC.

  13. Reduced inflammation in the tumor microenvironment delays the accumulation of myeloid-derived suppressor cells and limits tumor progression.

    PubMed

    Bunt, Stephanie K; Yang, Linglin; Sinha, Pratima; Clements, Virginia K; Leips, Jeff; Ostrand-Rosenberg, Suzanne

    2007-10-15

    Chronic inflammation is frequently associated with malignant growth and is thought to promote and enhance tumor progression, although the mechanisms which regulate this relationship remain elusive. We reported previously that interleukin (IL)-1beta promoted tumor progression by enhancing the accumulation of myeloid-derived suppressor cells (MDSC), and hypothesized that inflammation leads to cancer through the production of MDSC which inhibit tumor immunity. If inflammation-induced MDSC promote tumor progression by blocking antitumor immunity, then a reduction in inflammation should reduce MDSC levels and delay tumor progression, whereas an increase in inflammation should increase MDSC levels and hasten tumor progression. We have tested this hypothesis using the 4T1 mammary carcinoma and IL-1 receptor (IL-1R)-deficient mice which have a reduced potential for inflammation, and IL-1R antagonist-deficient mice, which have an increased potential for inflammation. Consistent with our hypothesis, IL-1R-deficient mice have a delayed accumulation of MDSC and reduced primary and metastatic tumor progression. Accumulation of MDSC and tumor progression are partially restored by IL-6, indicating that IL-6 is a downstream mediator of the IL-1beta-induced expansion of MDSC. In contrast, excessive inflammation in IL-1R antagonist-deficient mice promotes the accumulation of MDSC and produces MDSC with enhanced suppressive activity. These results show that immune suppression by MDSC and tumor growth are regulated by the inflammatory milieu and support the hypothesis that the induction of suppressor cells which down-regulate tumor immunity is one of the mechanisms linking inflammation and cancer.

  14. Cellular senescence checkpoint function determines differential Notch1-dependent oncogenic and tumor-suppressor activities.

    PubMed

    Kagawa, S; Natsuizaka, M; Whelan, K A; Facompre, N; Naganuma, S; Ohashi, S; Kinugasa, H; Egloff, A M; Basu, D; Gimotty, P A; Klein-Szanto, A J; Bass, A J; Wong, K-K; Diehl, J A; Rustgi, A K; Nakagawa, H

    2015-04-30

    Notch activity regulates tumor biology in a context-dependent and complex manner. Notch may act as an oncogene or a tumor-suppressor gene even within the same tumor type. Recently, Notch signaling has been implicated in cellular senescence. Yet, it remains unclear as to how cellular senescence checkpoint functions may interact with Notch-mediated oncogenic and tumor-suppressor activities. Herein, we used genetically engineered human esophageal keratinocytes and esophageal squamous cell carcinoma cells to delineate the functional consequences of Notch activation and inhibition along with pharmacological intervention and RNA interference experiments. When expressed in a tetracycline-inducible manner, the ectopically expressed activated form of Notch1 (ICN1) displayed oncogene-like characteristics inducing cellular senescence corroborated by the induction of G0/G1 cell-cycle arrest, Rb dephosphorylation, flat and enlarged cell morphology and senescence-associated β-galactosidase activity. Notch-induced senescence involves canonical CSL/RBPJ-dependent transcriptional activity and the p16(INK4A)-Rb pathway. Loss of p16(INK4A) or the presence of human papilloma virus (HPV) E6/E7 oncogene products not only prevented ICN1 from inducing senescence but permitted ICN1 to facilitate anchorage-independent colony formation and xenograft tumor growth with increased cell proliferation and reduced squamous-cell differentiation. Moreover, Notch1 appears to mediate replicative senescence as well as transforming growth factor-β-induced cellular senescence in non-transformed cells and that HPV E6/E7 targets Notch1 for inactivation to prevent senescence, revealing a tumor-suppressor attribute of endogenous Notch1. In aggregate, cellular senescence checkpoint functions may influence dichotomous Notch activities in the neoplastic context.

  15. Functional evidence for a nasopharyngeal carcinoma tumor suppressor gene that maps at chromosome 3p21.3

    PubMed Central

    Cheng, Yue; Poulos, Nicholas E.; Lung, Maria L.; Hampton, Garret; Ou, Baoxiang; Lerman, Michael I.; Stanbridge, Eric J.

    1998-01-01

    Nasopharyngeal carcinoma is a malignancy that is prevalent among populations from Southeast Asia. Epidemiological studies indicate that genetic predisposition, Epstein–Barr virus, and environmental conditions may play a role in determining incidence. Molecular studies have implicated a tumor suppressor gene(s) on the short arm of chromosome 3. In this study we provide functional evidence, via monochromosome transfer, for a tumor suppressor gene(s) activity in chromosome 3p21.3. PMID:9501212

  16. Dnmt3a Is a Haploinsufficient Tumor Suppressor in CD8+ Peripheral T Cell Lymphoma

    PubMed Central

    Opavska, Jana; Klinkebiel, David; Roy, Sohini; Dutta, Samikshan; Datta, Kaustubh; Opavsky, Rene

    2016-01-01

    DNA methyltransferase 3A (DNMT3A) is an enzyme involved in DNA methylation that is frequently mutated in human hematologic malignancies. We have previously shown that inactivation of Dnmt3a in hematopoietic cells results in chronic lymphocytic leukemia in mice. Here we show that 12% of Dnmt3a-deficient mice develop CD8+ mature peripheral T cell lymphomas (PTCL) and 29% of mice are affected by both diseases. 10% of Dnmt3a+/- mice develop lymphomas, suggesting that Dnmt3a is a haploinsufficient tumor suppressor in PTCL. DNA methylation was deregulated genome-wide with 10-fold more hypo- than hypermethylated promoters and enhancers, demonstrating that hypomethylation is a major event in the development of PTCL. Hypomethylated promoters were enriched for binding sites of transcription factors AML1, NF-κB and OCT1, implying the transcription factors potential involvement in Dnmt3a-associated methylation. Whereas 71 hypomethylated genes showed an increased expression in PTCL, only 3 hypermethylated genes were silenced, suggesting that cancer-specific hypomethylation has broader effects on the transcriptome of cancer cells than hypermethylation. Interestingly, transcriptomes of Dnmt3a+/- and Dnmt3aΔ/Δ lymphomas were largely conserved and significantly overlapped with those of human tumors. Importantly, we observed downregulation of tumor suppressor p53 in Dnmt3a+/- and Dnmt3aΔ/Δ lymphomas as well as in pre-tumor thymocytes from 9 months old but not 6 weeks old Dnmt3a+/- tumor-free mice, suggesting that p53 downregulation is chronologically an intermediate event in tumorigenesis. Decrease in p53 is likely an important event in tumorigenesis because its overexpression inhibited proliferation in mouse PTCL cell lines, suggesting that low levels of p53 are important for tumor maintenance. Altogether, our data link the haploinsufficient tumor suppressor function of Dnmt3a in the prevention of mouse mature CD8+ PTCL indirectly to a bona fide tumor suppressor of T cell

  17. Regulation of protein phosphatase 2A (PP2A) tumor suppressor function by PME-1.

    PubMed

    Kaur, Amanpreet; Westermarck, Jukka

    2016-12-15

    Protein phosphatase 2A (PP2A) plays a major role in maintaining cellular signaling homeostasis by dephosphorylation of a variety of signaling proteins and acts as a tumor suppressor. Protein phosphatase methylesterase-1 (PME-1) negatively regulates PP2A activity by highly complex mechanisms that are reviewed here. Importantly, recent studies have shown that PME-1 promotes oncogenic MAPK/ERK and AKT pathway activities in various cancer types. In human glioma, high PME-1 expression correlates with tumor progression and kinase inhibitor resistance. We discuss the emerging cancer-associated function of PME-1 and its potential clinical relevance.

  18. SIRT3 is a Mitochondrial Tumor Suppressor and Genetic Loss Results in a Murine Model for ER/PR-Positive Mammary Tumors Connecting Metabolism and Carcinogenesis Mitochondrial Tumor Suppressor. Revision

    DTIC Science & Technology

    2013-11-01

    breast cancer in younger women have been established by altering the expression of BRCA genes . In contrast, there are no murine models for the...overarching goal of this proposal is to determine if the mitochondrial sirtuin SIRT3 is a tumor suppressor gene (TSG) that may be used to: (1...tumors. Based on these results we initially proposed a hypothesis that longevity genes impact the process of carcinogenesis via the maintenance of

  19. Whole chromosome instability caused by Bub1 insufficiency drives tumorigenesis through tumor suppressor gene loss of heterozygosity

    PubMed Central

    Baker, Darren J.; Jin, Fang; Jeganathan, Karthik B.; van Deursen, Jan M.

    2010-01-01

    Summary Genetic alterations that promote chromosome missegregation have been proposed to drive tumorigenesis through loss of whole chromosomes containing key tumor suppressor genes. To test this unproven idea, we bred Bub1 mutant mice that inaccurately segregate their chromosomes onto p53+/−, ApcMin/+, Rb+/− or Pten+/− backgrounds. Bub1 insufficiency predisposed p53+/− mice to thymic lymphomas and ApcMin/+ mice to colonic tumors. These tumors consistently lacked the non-mutated tumor suppressor allele, but had gained a copy of the mutant allele. In contrast, Bub1 insufficiency had no impact on tumorigenesis in Rb+/− mice and inhibited prostatic intraepithelial neoplasia formation in Pten+/− mice. Thus, Bub1 insufficiency can drive tumor formation through tumor suppressor gene loss of heterozygosity, but only in restricted genetic and cellular contexts. PMID:19962666

  20. LSAMP, a novel candidate tumor suppressor gene in human osteosarcomas, identified by array comparative genomic hybridization.

    PubMed

    Kresse, Stine H; Ohnstad, Hege O; Paulsen, Erik B; Bjerkehagen, Bodil; Szuhai, Karoly; Serra, Massimo; Schaefer, Karl-Ludwig; Myklebost, Ola; Meza-Zepeda, Leonardo A

    2009-08-01

    Osteosarcomas are the most common primary malignant tumor of bone, and almost all conventional osteosarcomas are high-grade tumors with complex karyotypes. We have examined DNA copy number changes in 36 osteosarcoma tumors and 20 cell lines using microarray-based comparative genomic hybridization. The most frequent minimal recurrent regions of gain identified in the tumor samples were in 1q21.2-q21.3 (78% of the samples), 1q21.3-q22 (78%), and 8q22.1 (72%). Minimal recurrent regions in 10q22.1-q22.2 (81%), 6q16.1 (67%), 13q14.2 (67%), and 13q21.1 (67%) were most frequently lost. A small region in 3q13.31 (2.1 Mb) containing the gene limbic system-associated membrane protein (LSAMP) was frequently deleted (56%). LSAMP has previously been reported to be a candidate tumor suppressor gene in other cancer types. The deletion was validated using fluorescence in situ hybridization, and the expression level and promoter methylation status of LSAMP were investigated using quantitative real-time reverse transcription PCR and methylation-specific PCR, respectively. LSAMP showed low expression compared to two normal bone samples in 6/15 tumors and 5/9 cell lines with deletion of 3q13.31, and also in 5/14 tumors and 3/11 cell lines with normal copy number or gain. Partial or full methylation of the investigated CpG island was identified in 3/30 tumors and 7/20 cell lines. Statistical analyses revealed that loss of 11p15.4-p15.3 and low expression of LSAMP (both P = 0.011) were significantly associated with poor survival. Our results show that LSAMP is a novel candidate tumor suppressor gene in osteosarcomas.

  1. The ETS transcription factor MEF is a candidate tumor suppressor gene on the X chromosome.

    PubMed

    Seki, Yoshiyuki; Suico, Mary Ann; Uto, Ayako; Hisatsune, Akinobu; Shuto, Tsuyoshi; Isohama, Yoichiro; Kai, Hirofumi

    2002-11-15

    Although X chromosome transfer experiments indicated that tumor suppressor genes are present on the X chromosome, they have not been previously identified. In this report, we show that the ETS transcription factor MEF (ELF4), which is located on chromosome Xq26.1, possesses tumor suppressive capability. MEF expression was up-regulated by 5-azacytidine in some cancer cell lines. MEF overexpression induced morphological changes, such as the conversion of normally loose cell-cell contacts to strong interactions similar to those seen in the presence of matrix metalloproteinase (MMP) inhibitor BB94. In the colony formation assay, A549 cells, but not MEF-overexpressing cells, formed colonies in soft agar culture. Furthermore, MEF-overexpressing cells s.c. injected in the nude mice did not grow, whereas the control cells did. The A549 tumors were poorly differentiated, whereas the MEF-overexpressing tumors were well differentiated. By immunostaining with CD31, a marker on vascular endothelial cells, we found that tumor angiogenesis was significantly suppressed in the tumors formed from MEF-overexpressing cells. In addition, the conditioned media from A549 cell cultures stimulated the migration of human umbilical vein endothelial cells, whereas conditioned media from MEF-overexpressing cell cultures had less of an effect. By gelatin zymography, Western blotting analysis, and immunohistochemistry, we found that the expression levels of MMP-9 and MMP-2 were significantly reduced in MEF-overexpressing tumors. Immunohistochemical analyses showed that interleukin (IL)-8 expression was reduced in the MEF-overexpressing tumors in nude mice. Furthermore, IL-8 mRNA expression in vitro was significantly down-regulated in MEF-overexpressing cells, compared with A549 cells. MEF suppressed the transcription and promoter activities of the genes encoding MMP-9 and IL-8, whereas ETS-2 up-regulated these activities. Therefore, we propose that MEF is a candidate tumor suppressor gene on the

  2. Prostaglandin E2 promotes tumor progression by inducing myeloid-derived suppressor cells.

    PubMed

    Sinha, Pratima; Clements, Virginia K; Fulton, Amy M; Ostrand-Rosenberg, Suzanne

    2007-05-01

    A causative relationship between chronic inflammation and cancer has been postulated for many years, and clinical observations and laboratory experiments support the hypothesis that inflammation contributes to tumor onset and progression. However, the precise mechanisms underlying the relationship are not known. We recently reported that the proinflammatory cytokine, interleukin-1beta, induces the accumulation and retention of myeloid-derived suppressor cells (MDSC), which are commonly found in many patients and experimental animals with cancer and are potent suppressors of adaptive and innate immunity. This finding led us to hypothesize that inflammation leads to cancer through the induction of MDSC, which inhibit immunosurveillance and thereby allow the unchecked persistence and proliferation of premalignant and malignant cells. We now report that host MDSC have receptors for prostaglandin E2 (PGE2) and that E-prostanoid receptor agonists, including PGE2, induce the differentiation of Gr1(+)CD11b(+) MDSC from bone marrow stem cells, whereas receptor antagonists block differentiation. BALB/c EP2 knockout mice inoculated with the spontaneously metastatic BALB/c-derived 4T1 mammary carcinoma have delayed tumor growth and reduced numbers of MDSC relative to wild-type mice, suggesting that PGE2 partially mediates MDSC induction through the EP2 receptor. Treatment of 4T1-tumor-bearing wild-type mice with the cyclooxygenase 2 inhibitor, SC58236, delays primary tumor growth and reduces MDSC accumulation, further showing that PGE2 induces MDSC and providing a therapeutic approach for reducing this tumor-promoting cell population.

  3. Gene trapping identifies a putative tumor suppressor and a new inducer of cell migration

    SciTech Connect

    Guardiola-Serrano, Francisca; Haendeler, Judith; Lukosz, Margarete; Sturm, Karsten; Melchner, Harald von; Altschmied, Joachim

    2008-11-28

    Tumor necrosis factor alpha (TNF{alpha}) is a pleiotropic cytokine involved in apoptotic cell death, cellular proliferation, differentiation, inflammation, and tumorigenesis. In tumors it is secreted by tumor associated macrophages and can have both pro- and anti-tumorigenic effects. To identify genes regulated by TNF{alpha}, we performed a gene trap screen in the mammary carcinoma cell line MCF-7 and recovered 64 unique, TNF{alpha}-induced gene trap integration sites. Among these were the genes coding for the zinc finger protein ZC3H10 and for the transcription factor grainyhead-like 3 (GRHL3). In line with the dual effects of TNF{alpha} on tumorigenesis, we found that ZC3H10 inhibits anchorage independent growth in soft agar suggesting a tumor suppressor function, whereas GRHL3 strongly stimulated the migration of endothelial cells which is consistent with an angiogenic, pro-tumorigenic function.

  4. ANRIL: a pivotal tumor suppressor long non-coding RNA in human cancers.

    PubMed

    Li, Zheng; Yu, Xin; Shen, Jianxiong

    2016-05-01

    Long non-coding RNAs (lncRNAs) are a family of non-protein-coding RNAs with length more than 200 nucleotides. LncRNAs played important roles in many biological processes such as cell development, proliferation, invasion and migration. Deregulation of LncRNAs was found in multiple tumors where they can act as a tumor suppressor gene or oncogene. LncRNA ANRIL was identified as an oncogene involved in a number of tumors such as gastric cancer, lung cancer, hepatocellular carcinoma, and esophageal squamous cell carcinoma. Inhibition of ANRIL suppressed the cancer cell proliferation, migration and invasion. Increasing data has showed that ANRIL may act as a diagnostic and prognostic biomarker for some tumors. In our review, we summarize an overview of current knowledge concerning the expression and role of ANRIL in various cancers.

  5. Inhibition of tumor-induced myeloid-derived suppressor cell function by a nanoparticulated adjuvant.

    PubMed

    Fernández, Audry; Mesa, Circe; Marigo, Ilaria; Dolcetti, Luigi; Clavell, Marilyn; Oliver, Liliana; Fernández, Luis E; Bronte, Vincenzo

    2011-01-01

    The interaction between cancer vaccine adjuvants and myeloid-derived suppressor cells (MDSCs) is currently poorly understood. Very small size proteoliposomes (VSSP) are a nanoparticulated adjuvant under investigation in clinical trials in patients with renal carcinoma, breast cancer, prostate cancer, and cervical intraepithelial neoplasia grade III. We found that VSSP adjuvant induced a significant splenomegaly due to accumulation of CD11b(+)Gr-1(+) cells. However, VSSP-derived MDSCs showed a reduced capacity to suppress both allogeneic and Ag-specific CTL response compared with that of tumor-induced MDSCs. Moreover, splenic MDSCs isolated from tumor-bearing mice treated with VSSP were phenotypically more similar to those isolated from VSSP-treated tumor-free mice and much less suppressive than tumor-induced MDSCs, both in vitro and in vivo. Furthermore, different from dendritic cell vaccination, inoculation of VSSP-based vaccine in EG.7-OVA tumor-bearing mice was sufficient to avoid tumor-induced tolerance and stimulate an immune response against OVA Ag, similar to that observed in tumor-free mice. This effect correlated with an accelerated differentiation of MDSCs into mature APCs that was promoted by VSSP. VSSP used as a cancer vaccine adjuvant might thus improve antitumor efficacy not only by stimulating a potent immune response against tumor Ags but also by reducing tumor-induced immunosuppression.

  6. Tumor suppressor function of Betaig-H3 gene in radiation carcinogenesis

    NASA Astrophysics Data System (ADS)

    Zhao, Y. L.; Piao, C. Q.; Hei, T. K.

    Interaction between cell and extracellular matrix (ECM) plays a crucial role in tumor invasiveness and metastasis. Using an immortalized human bronchial epithelial (BEP2D) cell model, we showed previously that expression of a list of genes including Betaig-h3 (induced by transforming growth factor-β) DCC (deleted in colorectal cancer), p21 cip1, c-fos , Heat shock protein (HSP27) and cytokeratin 14 were differentially expressed in several independently generated, radiation-induced tumor cell lines (TL1-TL5) relative to parental BEP2D cells. Our previous data further demonstrated that loss of tumor suppressor gene(s) as a likely mechanism of radiation carcinogenesis. In the present study, we chose Betaig-h3 and DCC that were downregulated in tumorigenic cells for further study. Restored expression of Betaig-h3 gene, not DCC gene, by transfecting cDNA into tumor cells resulted in a significant reduction in tumor growth. While integrin receptor α5β1 was overexpressed in tumor cells, its expression was corrected to the level found in control BEP2D cells after Betaig-h3 transfection. These data suggest that Betaig-h3 gene is involved in tumor progression by regulating integrin α5β1 receptor. Furthermore, exogenous TGF-β1 induced expression of Betaig-h3 gene and inhibited the growth of both control and tumorigenic BEP2D cells. Therefore, downregulation of Betaig-h3 gene may results from the decreased expression of upstream mediators such as TGF-β. The findings provide strong evidence that the Betaig-h3 gene has tumor suppressor function in radiation-induced tumorigenic human bronchial epithelial cells and suggest a potential target for interventional therapy.

  7. MicroRNA-103 promotes colorectal cancer by targeting tumor suppressor DICER and PTEN.

    PubMed

    Geng, Li; Sun, Bing; Gao, Bo; Wang, Zheng; Quan, Cheng; Wei, Feng; Fang, Xue-Dong

    2014-05-13

    MicroRNAs (miRNAs) are a class of small, noncoding RNAs that act as key regulators in various physiological and pathological processes. However, the regulatory mechanisms for miRNAs in colorectal cancer remain largely unknown. Here, we found that miR-103 is up-regulated in colorectal cancer and its overexpression is closely associated with tumor proliferation and migration. In addition, repressing the expression of miR-103 apparently inhibits colorectal cancer cell proliferation and migration in vitro and HCT-116 xenograft tumor growth in vivo. Subsequent software analysis and dual-luciferase reporter assay identified two tumor suppressor genes DICER and PTEN as direct targets of miR-103, and up-regulation of DICER and PTEN obtained similar results to that occurred in the silencing of miR-103. In addition, restoration of DICER and PTEN can inhibit miR-103-induced colorectal cancer cell proliferation and migration. Our data collectively demonstrate that miR-103 is an oncogene miRNA that promotes colorectal cancer proliferation and migration through down-regulation of the tumor suppressor genes DICER and PTEN. Thus, miR-103 may represent a new potential diagnostic and therapeutic target for colorectal cancer treatment.

  8. The retinoblastoma gene functions as a growth and tumor suppressor in human bladder carcinoma cells

    SciTech Connect

    Takahashi, Rei; Hashimoto, Tomoko; Hongji Xu; Shixu Hu; Bigo-Marshall, H.; Benedict, W.F. ); Matsui, Toshimitsu Kobe Univ. School of Medicine ); Miki, Toru; Aaronson, S.A. )

    1991-06-15

    The product of the human retinoblastoma gene (RB) is a nuclear phosphoprotein that is thought to function as a tumor suppressor. Mutations of RB frequently occur in human bladder carcinoma. To investigate the significance of the functional loss of this gene in bladder cancer, an RB expression plasmid (pBARB) under control of the human {beta}-actin promoter was transfected into the bladder carcinoma cell line HTB9, which lacks RB expression. Marker-selected transfectants that expressed RB protein were identified by immunoblotting and immunohistochemical staining. In selected clones, stable RB expression has persisted over 1 yr under standard culture conditions with 10% serum. However, RB expression caused major alterations of HTB9 growth properties both in vitro and in vivo. RB{sup +} tranfectants lacked the ability to form colonies in semi-solid medium, and their growth rate was significantly decreased in 3% serum. In addition, the tumorigenicity of these transfectants was markedly decreased. Tumors that formed in nude mice were much smaller and had a longer latency period but were indistinguishable microscopically from those produced by parental cells. Slower growing tumors were RB{sup +}, as measured by nuclear staining of their RB protein and by a normal RB protein pattern on immunoblots. These findings support the concept that the RB gene acts as both a growth and tumor suppressor in bladder cancer cells.

  9. Autophagy inhibits oxidative stress and tumor suppressors to exert its dual effect on hepatocarcinogenesis.

    PubMed

    Tian, Y; Kuo, C-F; Sir, D; Wang, L; Govindarajan, S; Petrovic, L M; Ou, J-H J

    2015-06-01

    The role of autophagy in carcinogenesis is controversial and apparently complex. By using mice with hepatocyte-specific knockout of Atg5, a gene essential for autophagy, we longitudinally studied the role of autophagy in hepatocarcinogenesis. We found that impairing autophagy in hepatocytes would induce oxidative stress and DNA damage, followed by the initiation of hepatocarcinogenesis, which could be suppressed by the antioxidant N-acetylcysteine. Interestingly, these mice developed only benign tumors with no hepatocellular carcinoma (HCC), even after the treatment with diethylnitrosamine, which induced HCC in wild-type mice. The inability of mice to develop HCC when autophagy was impaired was associated with the induction of multiple tumor suppressors including p53. Further analysis indicated that the induction of p53 was associated with the DNA-damage response. Tumorigenesis studies using an established liver tumor cell line confirmed a positive role of autophagy in tumorigenesis and a negative role of p53 in this process when autophagy was impaired. Our studies thus demonstrate that autophagy is required to maintain healthy mitochondria and to reduce oxidative stress and DNA damage to prevent the initiation of hepatocarcinogenesis. However, once hepatocarcinogenesis has been initiated, its presence is also required to suppress the expression of tumor suppressors to promote the development of HCC.

  10. Connection between Tumor Suppressor BRCA1 and PTEN in Damaged DNA Repair.

    PubMed

    Minami, Akari; Nakanishi, Atsuko; Ogura, Yasunori; Kitagishi, Yasuko; Matsuda, Satoru

    2014-01-01

    Genomic instability finally induces cell death or apoptosis. The tumor suppressor, phosphatase and tensin homolog on chromosome 10 (PTEN), is a dual-specificity phosphatase, which has protein phosphatase activity and lipid phosphatase activity that antagonizes PI3K activity. Cells that lack PTEN have constitutively higher levels of PIP3 and activated downstream PI3K/AKT targets. BRCA1, a well-known breast cancer tumor suppressor, is to associate with breast cancer risk and genetic susceptibility. Many studies have demonstrated that PTEN, as well as BRCA1, plays a critical role in DNA damage responses. The BRCA1 functionally cooperates with PTEN and might be an essential blockage in the development of several tumors. Actually, the PTEN and BRCA1 genes are recognized as one of the most frequently deleted and/or mutated in many human cancers. The PI3K/AKT pathway is constitutively active in BRCA1-defective human cancer cells. Loss or decrease of these PTEN or BRCA1 function, by either mutation or reduced expression, has a role in various tumor developments. This review summarizes recent findings of the function of BRCA1 and PTEN involved in genomic stability and cancer cell signaling.

  11. Molecular chaperone Hsp27 regulates the Hippo tumor suppressor pathway in cancer

    PubMed Central

    Vahid, Sepideh; Thaper, Daksh; Gibson, Kate F.; Bishop, Jennifer L.; Zoubeidi, Amina

    2016-01-01

    Heat shock protein 27 (Hsp27) is a molecular chaperone highly expressed in aggressive cancers, where it is involved in numerous pro-tumorigenic signaling pathways. Using functional genomics we identified for the first time that Hsp27 regulates the gene signature of transcriptional co-activators YAP and TAZ, which are negatively regulated by the Hippo Tumor Suppressor pathway. The Hippo pathway inactivates YAP by phosphorylating and increasing its cytoplasmic retention with the 14.3.3 proteins. Gain and loss of function experiments in prostate, breast and lung cancer cells showed that Hsp27 knockdown induced YAP phosphorylation and cytoplasmic localization while overexpression of Hsp27 displayed opposite results. Mechanistically, Hsp27 regulates the Hippo pathway by accelerating the proteasomal degradation of ubiquitinated MST1, the core Hippo kinase, resulting in reduced phosphorylation/activity of LATS1 and MOB1, its downstream effectors. Importantly, our in vitro results were supported by data from human tumors; clinically, high expression of Hsp27 in prostate tumors is correlated with increased expression of YAP gene signature and reduced phosphorylation of YAP in lung and invasive breast cancer clinical samples. This study reveals for the first time a link between Hsp27 and the Hippo cascade, providing a novel mechanism of deregulation of this tumor suppressor pathway across multiple cancers. PMID:27555231

  12. Aggregation and Prion-Like Properties of Misfolded Tumor Suppressors: Is Cancer a Prion Disease?

    PubMed

    Costa, Danielly C F; de Oliveira, Guilherme A P; Cino, Elio A; Soares, Iaci N; Rangel, Luciana P; Silva, Jerson L

    2016-10-03

    Prion diseases are disorders that share several characteristics that are typical of many neurodegenerative diseases. Recently, several studies have extended the prion concept to pathological aggregation in malignant tumors involving misfolded p53, a tumor-suppressor protein. The aggregation of p53 and its coaggregation with p53 family members, p63 and p73, have been shown. Certain p53 mutants exert a dominant-negative regulatory effect on wild-type (WT) p53. The basis for this dominant-negative effect is that amyloid-like mutant p53 converts WT p53 into an aggregated species, leading to a gain-of-function (GoF) phenotype and the loss of its tumor-suppressor function. Recently, it was shown that p53 aggregates can be internalized by cells and can coaggregate with endogenous p53, corroborating the prion-like properties of p53 aggregates. The prion-like behavior of oncogenic p53 mutants provides an explanation for its dominant-negative and GoF properties, including the high metastatic potential of cancer cells carrying p53 mutations. The inhibition of p53 aggregation appears to represent a promising target for therapeutic intervention in patients with malignant tumors.

  13. Simultaneous loss of the DLC1 and PTEN tumor suppressors enhances breast cancer cell migration

    SciTech Connect

    Heering, Johanna; Erlmann, Patrik; Olayioye, Monilola A.

    2009-09-10

    The phosphatase and tensin homolog (PTEN) gene is a tumor suppressor frequently deleted or mutated in sporadic tumors of the breast, prostate, endometrium and brain. The protein acts as a dual specificity phosphatase for lipids and proteins. PTEN loss confers a growth advantage to cells, protects from apoptosis and favors cell migration. The deleted in liver cancer 1 (DLC1) gene has emerged as a novel tumor suppressor downregulated in a variety of tumor types including those of the breast. DLC1 contains a Rho GTPase activating domain that is involved in the inhibition of cell proliferation, migration and invasion. To investigate how simultaneous loss of PTEN and DLC1 contributes to cell transformation, we downregulated both proteins by RNA interference in the non-invasive MCF7 breast carcinoma cell line. Joint depletion of PTEN and DLC1 resulted in enhanced cell migration in wounding and chemotactic transwell assays. Interestingly, both proteins were found to colocalize at the plasma membrane and interacted physically in biochemical pulldowns and coimmunoprecipitations. We therefore postulate that the concerted local inactivation of signaling pathways downstream of PTEN and DLC1, respectively, is required for the tight control of cell migration.

  14. A CRISPR/Cas9 Functional Screen Identifies Rare Tumor Suppressors

    PubMed Central

    Katigbak, Alexandra; Cencic, Regina; Robert, Francis; Sénécha, Patrick; Scuoppo, Claudio; Pelletier, Jerry

    2016-01-01

    An enormous amount of tumor sequencing data has been generated through large scale sequencing efforts. The functional consequences of the majority of mutations identified by such projects remain an open, unexplored question. This problem is particularly complicated in the case of rare mutations where frequency of occurrence alone or prediction of functional consequences are insufficient to distinguish driver from passenger or bystander mutations. We combine genome editing technology with a powerful mouse cancer model to uncover previously unsuspected rare oncogenic mutations in Burkitt’s lymphoma. We identify two candidate tumor suppressors whose loss cooperate with MYC over-expression to accelerate lymphomagenesis. Our results highlight the utility of in vivo CRISPR/Cas9 screens combined with powerful mouse models to identify and validate rare oncogenic modifier events from tumor mutational data. PMID:27982060

  15. ZBTB7A acts as a tumor suppressor through the transcriptional repression of glycolysis.

    PubMed

    Liu, Xue-Song; Haines, Jenna E; Mehanna, Elie K; Genet, Matthew D; Ben-Sahra, Issam; Asara, John M; Manning, Brendan D; Yuan, Zhi-Min

    2014-09-01

    Elevated glycolysis is a common metabolic trait of cancer, but what drives such metabolic reprogramming remains incompletely clear. We report here a novel transcriptional repressor-mediated negative regulation of glycolysis. ZBTB7A, a member of the POK (POZ/BTB and Krüppel) transcription repressor family, directly binds to the promoter and represses the transcription of critical glycolytic genes, including GLUT3, PFKP, and PKM. Analysis of The Cancer Genome Atlas (TCGA) data sets reveals that the ZBTB7A locus is frequently deleted in many human tumors. Significantly, reduced ZBTB7A expression correlates with up-regulation of the glycolytic genes and poor survival in colon cancer patients. Remarkably, while ZBTB7A-deficient tumors progress exceedingly fast, they exhibit an unusually heightened sensitivity to glycolysis inhibition. Our study uncovers a novel tumor suppressor role of ZBTB7A in directly suppressing glycolysis.

  16. Interleukin 6 supports the maintenance of p53 tumor suppressor gene promoter methylation.

    PubMed

    Hodge, David R; Peng, Benjamin; Cherry, James C; Hurt, Elaine M; Fox, Stephen D; Kelley, James A; Munroe, David J; Farrar, William L

    2005-06-01

    A strong association exists between states of chronic inflammation and cancer, and it is believed that mediators of inflammation may be responsible for this phenomenon. Interleukin 6 (IL-6) is an inflammatory cytokine known to play a role in the growth and survival of many types of tumors, yet the mechanisms employed by this pleomorphic cytokine to accomplish this feat are still poorly understood. Another important factor in tumor development seems to be the hypermethylation of CpG islands located within the promoter regions of tumor suppressor genes. This common epigenetic alteration enables tumor cells to reduce or inactivate the expression of important tumor suppressor and cell cycle regulatory genes. Here we show that in the IL-6-responsive human multiple myeloma cell line KAS 6/1, the promoter region of p53 is epigenetically modified by methyltransferases, resulting in decreased levels of expression. Furthermore, cells treated with IL-6 exhibit an increase in the expression of the DNA maintenance methylation enzyme, DNMT-1. The DNA methyltransferase inhibitor zebularine reverses the methylation of the p53 promoter, allowing the resumption of its expression. However, when zebularine is withdrawn from the cells, the reestablishment of the original CpG island methylation within the p53 promoter does not occur in the absence of IL-6, and cells which do not receive IL-6 eventually die, as p53 expression continues unchecked by remethylation. Interestingly, this loss of viability seems to involve not the withdrawal of cytokine, but the inability of the cell to resilence the promoter. Consistent with this model, when cells that express IL-6 in an autocrine fashion are subjected to identical treatment, p53 expression is reduced shortly after withdrawal of zebularine. Therefore, it seems IL-6 is capable of maintaining promoter methylation thus representing one of the possible mechanisms used by inflammatory mediators in the growth and survival of tumors.

  17. Tumor suppressor ARF regulates tissue microenvironment and tumor growth through modulation of macrophage polarization

    PubMed Central

    Jiménez-García, Lidia; Herranz, Sandra; Higueras, María Angeles

    2016-01-01

    Tumor microenvironment has been described to play a key role in tumor growth, progression, and metastasis. Macrophages are a major cellular constituent of the tumor stroma, and particularly tumor associated macrophages (TAMs or M2-like macrophages) exert important immunosuppressive activity and a pro-tumoral role within the tumor microenvironment. Alternative-reading frame (ARF) gene is widely inactivated in human cancer. We have previously demonstrated that ARF deficiency severely impairs inflammatory response establishing a new role for ARF in the regulation of innate immunity. On the basis of these observations, we hypothesized that ARF may also regulates tumor growth through recruitment and modulation of the macrophage phenotype in the tumor microenvironment. Xenograft assays of B16F10 melanoma cells into ARF-deficient mice resulted in increased tumor growth compared to those implanted in WT control mice. Tumors from ARF-deficient mice exhibited significantly increased number of TAMs as well as microvascular density. Transwell assays showed crosstalk between tumor cells and macrophages. On the one hand, ARF-deficient macrophages modulate migratory ability of the tumor cells. And on the other, tumor cells promote the skewing of ARF−/− macrophages toward a M2-type polarization. In conclusion, these results demonstrate that ARF deficiency facilitates the infiltration of macrophages into the tumor mass and favors their polarization towards a M2 phenotype, thus promoting tumor angiogenesis and tumor growth. This work provides novel information about the critical role of ARF in the modulation of tumor microenvironment. PMID:27572316

  18. Isoform-specific interactions of the von Hippel-Lindau tumor suppressor protein

    PubMed Central

    Minervini, Giovanni; Mazzotta, Gabriella M.; Masiero, Alessandro; Sartori, Elena; Corrà, Samantha; Potenza, Emilio; Costa, Rodolfo; Tosatto, Silvio C. E.

    2015-01-01

    Deregulation of the von Hippel-Lindau tumor suppressor protein (pVHL) is considered one of the main causes for malignant renal clear-cell carcinoma (ccRCC) insurgence. In human, pVHL exists in two isoforms, pVHL19 and pVHL30 respectively, displaying comparable tumor suppressor abilities. Mutations of the p53 tumor suppressor gene have been also correlated with ccRCC insurgence and ineffectiveness of treatment. A recent proteomic analysis linked full length pVHL30 with p53 pathway regulation through complex formation with the p14ARF oncosuppressor. The alternatively spliced pVHL19, missing the first 53 residues, lacks this interaction and suggests an asymmetric function of the two pVHL isoforms. Here, we present an integrative bioinformatics and experimental characterization of the pVHL oncosuppressor isoforms. Predictions of the pVHL30 N-terminus three-dimensional structure suggest that it may exist as an ensemble of structured and disordered forms. The results were used to guide Yeast two hybrid experiments to highlight isoform-specific binding properties. We observed that the physical pVHL/p14ARF interaction is specifically mediated by the 53 residue long pVHL30 N-terminal region, suggesting that this N-terminus acts as a further pVHL interaction interface. Of note, we also observed that the shorter pVHL19 isoform shows an unexpected high tendency to form homodimers, suggesting an additional isoform-specific binding specialization. PMID:26211615

  19. MiRNA-34 intrinsically links p53 tumor suppressor and Wnt signaling.

    PubMed

    Cha, Yong Hoon; Kim, Nam Hee; Park, Changbum; Lee, Inhan; Kim, Hyun Sil; Yook, Jong In

    2012-04-01

    Though tumor suppressor p53 and the canonical Wnt cascade have been extensively studied for the last 30 years, due to their important physiological roles, the two signaling pathways have been largely considered independent. Recently, the miR-34 family was found to directly link p53 and Wnt, revealing the tight connection between loss of tumor suppressor function and activation of oncogenic signaling. These observations demonstrate that miR-34, known to be directly downstream of p53, targets a set of highly conserved sites in the UTR of Wnt and EMT genes, specifically WNT1, WNT3, LRP6, AXIN2, β-catenin, LEF1 and Snail, resulting in suppression of TCF/LEF transcriptional activity and the EMT program. The loss of p53 function increases Wnt activities and promotes the Snail-dependent EMT program at multiple levels in a miR-34/UTR-specific manner. The TCF/LEF transcriptional signature was closely associated with functionality of p53 and miR-34 in clinical samples, suggesting the pervasive impact of miR-34 loss on the oncogenic pathway in human cancer. Here, we review recent findings on ceRNA in light of novel data to elucidate the physiological relevance of the p53-miR-34-Wnt network, which encompasses sets of genes and directions of signaling. As loss of wt-p53 or hyperactivation of Wnt is critical in maintaining cancer stem cell properties and in establishing the metastatic program, these observations indicate a mechanism of miR-mediated quasi-sufficiency which connects tumor suppressor and oncogenic signaling pathways, supporting a continuum model of human cancer.

  20. The Regulation of Tumor Suppressor p63 by the Ubiquitin-Proteasome System

    PubMed Central

    Armstrong, Stephen R.; Wu, Hong; Wang, Benfan; Abuetabh, Yasser; Sergi, Consolato; Leng, Roger P.

    2016-01-01

    The protein p63 has been identified as a homolog of the tumor suppressor protein p53 and is capable of inducing apoptosis, cell cycle arrest, or senescence. p63 has at least six isoforms, which can be divided into two major groups: the TAp63 variants that contain the N-terminal transactivation domain and the ΔNp63 variants that lack the N-terminal transactivation domain. The TAp63 variants are generally considered to be tumor suppressors involved in activating apoptosis and suppressing metastasis. ΔNp63 variants cannot induce apoptosis but can act as dominant negative inhibitors to block the function of TAp53, TAp73, and TAp63. p63 is rarely mutated in human tumors and is predominately regulated at the post-translational level by phosphorylation and ubiquitination. This review focuses primarily on regulation of p63 by the ubiquitin E-3 ligase family of enzymes via ubiquitination and proteasome-mediated degradation, and introduces a new key regulator of the p63 protein. PMID:27929429

  1. Dnmt3b is a haploinsufficient tumor suppressor gene in Myc-induced lymphomagenesis.

    PubMed

    Vasanthakumar, Aparna; Lepore, Janet B; Zegarek, Matthew H; Kocherginsky, Masha; Singh, Mahi; Davis, Elizabeth M; Link, Petra A; Anastasi, John; Le Beau, Michelle M; Karpf, Adam R; Godley, Lucy A

    2013-03-14

    The drivers of abnormal DNA methylation in human cancers include widespread aberrant splicing of the DNMT3B gene, producing abnormal transcripts that encode truncated proteins that may act as dominant negative isoforms. To test whether reduced Dnmt3b dosage can alter tumorigenesis, we bred Dnmt3b(+/-) mice to Eµ-Myc mice, a mouse model susceptible to B-cell lymphomas. Eµ-Myc/Dnmt3b(+/-) mice showed a dramatic acceleration of lymphomagenesis, greater even than that observed in Eµ-Myc mice that express a truncated DNMT3B isoform found in human tumors, DNMT3B7. This finding indicates that Dnmt3b can act as a haploinsufficient tumor suppressor gene. Although reduction in both Dnmt3b dosage and expression of DNMT3B7 within the Eµ-Myc system had similar effects on tumorigenesis and DNA hypermethylation, different molecular mechanisms appear to underlie these changes. This study offers insight into how de novo DNA methyltransferases function as tumor suppressors and the sensitivity of Myc-induced lymphomas to DNA methylation.

  2. [HINT1--a novel tumor suppressor protein of the HIT superfamily].

    PubMed

    Ozga, Magdalena

    2010-01-01

    The histidine triad nucleotide binding protein1 (Hint1) belongs to the first branch of the HIT superfamily. Hint1 catalyses the process of hydrolysis of the P-N bond in AMP-lysine, AMP-alanine, AMP-NH2. The physiological role of this enzyme is still unclear. There is accumulating evidence that HINT1 is a novel tumor suppressor protein, albeit the mechanism of action of HINT1 in respect to tumor suppression is not fully understood. Recent findings have shown that Hint1 inhibits the activity of the transcription factors AP1, MITF and USF2, as well as influences the transcription process of some genes of Wnt/beta-catenin pathway. Thereby, it seems that Hint1 exerts its major cellular function as gene transcription regulator, and thus, this function provides its potential role as a tumor suppressor protein. The clinical relevance of impairments in the Hint1 expression with the respect to specific human cancers is still a matter of extensive studies.

  3. PARP6 acts as a tumor suppressor via downregulating Survivin expression in colorectal cancer

    PubMed Central

    Liu, Tian; Jin, Shengjian; Liu, Jing; Zuo, Xiaoxu; Mi, Sisi; Shao, Wenhuan; Ma, Xiaojuan; Tsunematsu, Takaaki; Ishimaru, Naozumi; Zeng, Sien; Tatsuka, Masaaki; Shimamoto, Fumio

    2016-01-01

    Poly (ADP-ribose) polymerases (PARPs) are enzymes that transfer ADP-ribose groups to target proteins and are involved in a variety of biological processes. PARP6 is a novel member, and our previous findings suggest that PARP6 may act as a tumor suppressor via suppressing cell cycle progression. However, it is still unclear that PARP6 function besides growth suppression in colorectal cancer (CRC). In this study, we examined tumor suppressive roles of PAPR6 in CRC cells both in vitro and in vivo. We found that PARP6 inhibited colony formation, invasion and migration as well as cell proliferation. Moreover, ectopic overexpression of PARP6 decreased Survivin expression, which acts as an oncogene and is involved in apoptosis and mitosis. We confirmed the inverse correlation between PARP6 and Survivin expression in CRC cases by immunohistochemistry. Importantly, CRC cases with downregulation of PARP6 and upregulation of Survivin showed poor prognosis. In summary, PARP6 acts as a tumor suppressor via downregulating Survivin expression in CRC. PARP6 can be a novel diagnostic and therapeutic target together with Survivin for CRC. PMID:26934315

  4. The structure and function of NKAIN2-a candidate tumor suppressor

    PubMed Central

    Zhao, Shan-Chao; Zhou, Bo-Wei; Luo, Fei; Mao, Xueying; Lu, Yong-Jie

    2015-01-01

    The deletion of chromosomal region 6q was commonly found in several types of human cancers, although the tumor suppressor genes (TSGs) located within this genomic region are not well established. Our recent work detected recurrent chromosomal truncation at the Na+/K+ transporting ATPase interacting 2 (NKAIN2) gene in prostate cancer, which was also found to be truncated in leukemia and lymphoma, suggesting that NKAIN2 is potentially one of the TSGs located in the 6q commonly deleted region in human cancers. NKAIN2 gene consists of eight coding exons that span approximately 1 Mb of genomic DNA on chromosome 6q and there are four main splice variants. The function of this gene is not well investigated and the limited knowledge of this gene pointed to nervous system development. The chromosomal translocations in nervous development disorders usually lead to inactivation of this gene. In human tumors, both chromosomal deletion and translocation may also inactivate this gene and consequently contribute to tumorigenesis. Further genetic and cellular functional studies are required to establish its tumor suppressor role. PMID:26770299

  5. PAX5 is a tumor suppressor in mouse mutagenesis models of acute lymphoblastic leukemia

    PubMed Central

    Dang, Jinjun; Wei, Lei; de Ridder, Jeroen; Su, Xiaoping; Rust, Alistair G.; Roberts, Kathryn G.; Payne-Turner, Debbie; Cheng, Jinjun; Ma, Jing; Qu, Chunxu; Wu, Gang; Song, Guangchun; Huether, Robert G.; Schulman, Brenda; Janke, Laura; Zhang, Jinghui; Downing, James R.; van der Weyden, Louise; Adams, David J.

    2015-01-01

    Alterations of genes encoding transcriptional regulators of lymphoid development are a hallmark of B-progenitor acute lymphoblastic leukemia (B-ALL) and most commonly involve PAX5, encoding the DNA-binding transcription factor paired-box 5. The majority of PAX5 alterations in ALL are heterozygous, and key PAX5 target genes are expressed in leukemic cells, suggesting that PAX5 may be a haploinsufficient tumor suppressor. To examine the role of PAX5 alterations in leukemogenesis, we performed mutagenesis screens of mice heterozygous for a loss-of-function Pax5 allele. Both chemical and retroviral mutagenesis resulted in a significantly increased penetrance and reduced latency of leukemia, with a shift to B-lymphoid lineage. Genomic profiling identified a high frequency of secondary genomic mutations, deletions, and retroviral insertions targeting B-lymphoid development, including Pax5, and additional genes and pathways mutated in ALL, including tumor suppressors, Ras, and Janus kinase-signal transducer and activator of transcription signaling. These results show that in contrast to simple Pax5 haploinsufficiency, multiple sequential alterations targeting lymphoid development are central to leukemogenesis and contribute to the arrest in lymphoid maturation characteristic of ALL. This cross-species analysis also validates the importance of concomitant alterations of multiple cellular growth, signaling, and tumor suppression pathways in the pathogenesis of B-ALL. PMID:25855603

  6. Neuron-Specific Deletion of the Nf2 Tumor Suppressor Impairs Functional Nerve Regeneration

    PubMed Central

    Schulz, Alexander; Büttner, Robert; Toledo, Andrea; Baader, Stephan L.; von Maltzahn, Julia; Irintchev, Andrey; Bauer, Reinhard; Morrison, Helen

    2016-01-01

    In contrast to axons of the central nervous system (CNS), axons of the peripheral nervous system (PNS) show better, but still incomplete and often slow regeneration following injury. The tumor suppressor protein merlin, mutated in the hereditary tumor syndrome Neurofibromatosis type 2 (NF2), has recently been shown to have RhoA regulatory functions in PNS neurons—in addition to its well-characterized, growth-inhibitory activity in Schwann cells. Here we report that the conditional knockout of merlin in PNS neurons leads to impaired functional recovery of mice following sciatic nerve crush injury, in a gene-dosage dependent manner. Gross anatomical or electrophysiological alterations of sciatic nerves could not be detected. However, correlating with attenuated RhoA activation due to merlin deletion, ultrastructural analysis of nerve samples indicated enhanced sprouting of axons with reduced caliber size and increased myelination compared to wildtype animals. We conclude that deletion of the tumor suppressor merlin in the neuronal compartment of peripheral nerves results in compromised functional regeneration after injury. This mechanism could explain the clinical observation that NF2 patients suffer from higher incidences of slowly recovering facial nerve paralysis after vestibular schwannoma surgery. PMID:27467574

  7. The tumor suppressor semaphorin 3B triggers a prometastatic program mediated by interleukin 8 and the tumor microenvironment

    PubMed Central

    Rolny, Charlotte; Capparuccia, Lorena; Casazza, Andrea; Mazzone, Massimiliano; Vallario, Antonella; Cignetti, Alessandro; Medico, Enzo; Carmeliet, Peter; Comoglio, Paolo M.; Tamagnone, Luca

    2008-01-01

    Semaphorins are a large family of evolutionarily conserved morphogenetic molecules originally identified for their repelling role in axonal guidance. Intriguingly, semaphorins have recently been implicated in cancer progression (Neufeld, G., T. Lange, A. Varshavsky, and O. Kessler. 2007. Adv. Exp. Med. Biol. 600:118–131). In particular, semaphorin 3B (SEMA3B) is considered a putative tumor suppressor, and yet we found that it is expressed at high levels in many invasive and metastatic human cancers. By investigating experimental tumor models, we confirmed that SEMA3B expression inhibited tumor growth, whereas metastatic dissemination was surprisingly increased. We found that SEMA3B induced the production of interleukin (IL) 8 by tumor cells by activating the p38–mitogen-activated protein kinase pathway in a neuropilin 1–dependent manner. Silencing the expression of endogenous SEMA3B in tumor cells impaired IL-8 transcription. The release of IL-8, in turn, induced the recruitment of tumor-associated macrophages and metastatic dissemination to the lung, which could be rescued by blocking IL-8 with neutralizing antibodies. In conclusion, we report that SEMA3B exerts unexpected functions in cancer progression by fostering a prometastatic environment through elevated IL-8 secretion and recruitment of macrophages coupled to the suppression of tumor growth. PMID:18458115

  8. The tumor suppressor semaphorin 3B triggers a prometastatic program mediated by interleukin 8 and the tumor microenvironment.

    PubMed

    Rolny, Charlotte; Capparuccia, Lorena; Casazza, Andrea; Mazzone, Massimiliano; Vallario, Antonella; Cignetti, Alessandro; Medico, Enzo; Carmeliet, Peter; Comoglio, Paolo M; Tamagnone, Luca

    2008-05-12

    Semaphorins are a large family of evolutionarily conserved morphogenetic molecules originally identified for their repelling role in axonal guidance. Intriguingly, semaphorins have recently been implicated in cancer progression (Neufeld, G., T. Lange, A. Varshavsky, and O. Kessler. 2007. Adv. Exp. Med. Biol. 600:118-131). In particular, semaphorin 3B (SEMA3B) is considered a putative tumor suppressor, and yet we found that it is expressed at high levels in many invasive and metastatic human cancers. By investigating experimental tumor models, we confirmed that SEMA3B expression inhibited tumor growth, whereas metastatic dissemination was surprisingly increased. We found that SEMA3B induced the production of interleukin (IL) 8 by tumor cells by activating the p38-mitogen-activated protein kinase pathway in a neuropilin 1-dependent manner. Silencing the expression of endogenous SEMA3B in tumor cells impaired IL-8 transcription. The release of IL-8, in turn, induced the recruitment of tumor-associated macrophages and metastatic dissemination to the lung, which could be rescued by blocking IL-8 with neutralizing antibodies. In conclusion, we report that SEMA3B exerts unexpected functions in cancer progression by fostering a prometastatic environment through elevated IL-8 secretion and recruitment of macrophages coupled to the suppression of tumor growth.

  9. The tumor suppressor WW domain-containing oxidoreductase modulates cell metabolism.

    PubMed

    Abu-Remaileh, Muhannad; Aqeilan, Rami I

    2015-03-01

    The WW domain-containing oxidoreductase (WWOX) encodes a tumor suppressor that is frequently altered in cancer. WWOX binds several proteins and thus is postulated to be involved in a variety of cellular processes. Interestingly, Wwox-knockout mice develop normally in utero but succumb to hypoglycemia and other metabolic defects early in life resulting in their death by 3-4 weeks of age. Cumulative evidence has linked WWOX with cellular metabolism including steroid metabolism, high-density lipoprotein cholesterol (HDL-C) metabolism, bone metabolism and, more recently, glucose metabolism. In this review, we discuss these evolving functions for WWOX and how its deletion affects cellular metabolism and neoplastic progression.

  10. An in vivo screen identifies ependymoma oncogenes and tumor-suppressor genes.

    PubMed

    Mohankumar, Kumarasamypet M; Currle, David S; White, Elsie; Boulos, Nidal; Dapper, Jason; Eden, Christopher; Nimmervoll, Birgit; Thiruvenkatam, Radhika; Connelly, Michele; Kranenburg, Tanya A; Neale, Geoffrey; Olsen, Scott; Wang, Yong-Dong; Finkelstein, David; Wright, Karen; Gupta, Kirti; Ellison, David W; Thomas, Arzu Onar; Gilbertson, Richard J

    2015-08-01

    Cancers are characterized by non-random chromosome copy number alterations that presumably contain oncogenes and tumor-suppressor genes (TSGs). The affected loci are often large, making it difficult to pinpoint which genes are driving the cancer. Here we report a cross-species in vivo screen of 84 candidate oncogenes and 39 candidate TSGs, located within 28 recurrent chromosomal alterations in ependymoma. Through a series of mouse models, we validate eight new ependymoma oncogenes and ten new ependymoma TSGs that converge on a small number of cell functions, including vesicle trafficking, DNA modification and cholesterol biosynthesis, identifying these as potential new therapeutic targets.

  11. Hydroxylation-Dependent Interaction of Substrates to the Von Hippel-Lindau Tumor Suppressor Protein (VHL).

    PubMed

    Heir, Pardeep; Ohh, Michael

    2016-01-01

    Oxygen-dependent hydroxylation of critical proline residues, catalyzed by prolyl hydroxylase (PHD1-3) enzymes, is a crucial posttranslational modification (PTM) within the canonical hypoxia-inducible factor (HIF)-centric cellular oxygen-sensing pathway. Alteration of substrates in this way often leads to proteasomal degradation mediated by the von Hippel-Lindau Tumor Suppressor protein (VHL) containing E3-ubiquitin ligase complex known as ECV (Elongins B/C, CUL2, VHL). Here, we outline in vitro protocols to demonstrate the ability of VHL to bind to a prolyl-hydroxylated substrate.

  12. Fibronectin is a hypoxia-independent target of the tumor suppressor VHL.

    PubMed

    Bluyssen, Hans A R; Lolkema, Martijn P J K; van Beest, Moniek; Boone, Michelle; Snijckers, Cristel M J T; Los, Maartje; Gebbink, Martijn F B G; Braam, Branko; Holstege, Frank C P; Giles, Rachel H; Voest, Emile E

    2004-01-02

    The von Hippel-Lindau (VHL) tumor suppressor gene regulates the extracellular matrix by controlling fibronectin deposition. To identify novel VHL target genes, we subjected mRNA from VHL-deficient RCC cells (786-0-pRC) and a transfectant re-expressing wildtype VHL (786-0-VHL) to differential expression profiling. Among the differentially expressed genes, we detected that fibronectin is upregulated in the presence of VHL, while it is not affected by hypoxia. Thus regulation of fibronectin deposition by VHL occurs at the transcriptional level, irrespective of oxygen levels.

  13. Brush border Myosin Ia has tumor suppressor activity in the intestine

    PubMed Central

    Mazzolini, Rocco; Dopeso, Higinio; Mateo-Lozano, Silvia; Chang, Wakam; Rodrigues, Paulo; Bazzocco, Sarah; Alazzouzi, Hafid; Landolfi, Stefania; Hernández-Losa, Javier; Andretta, Elena; Alhopuro, Pia; Espín, Eloy; Armengol, Manel; Tabernero, Josep; Ramón y Cajal, Santiago; Kloor, Matthias; Gebert, Johannes; Mariadason, John M.; Schwartz, Simo; Aaltonen, Lauri A.; Mooseker, Mark S.; Arango, Diego

    2012-01-01

    The loss of the epithelial architecture and cell polarity/differentiation is known to be important during the tumorigenic process. Here we demonstrate that the brush border protein Myosin Ia (MYO1A) is important for polarization and differentiation of colon cancer cells and is frequently inactivated in colorectal tumors by genetic and epigenetic mechanisms. MYO1A frame-shift mutations were observed in 32% (37 of 116) of the colorectal tumors with microsatellite instability analyzed, and evidence of promoter methylation was observed in a significant proportion of colon cancer cell lines and primary colorectal tumors. The loss of polarization/differentiation resulting from MYO1A inactivation is associated with higher tumor growth in soft agar and in a xenograft model. In addition, the progression of genetically and carcinogen-initiated intestinal tumors was significantly accelerated in Myo1a knockout mice compared with Myo1a wild-type animals. Moreover, MYO1A tumor expression was found to be an independent prognostic factor for colorectal cancer patients. Patients with low MYO1A tumor protein levels had significantly shorter disease-free and overall survival compared with patients with high tumoral MYO1A (logrank test P = 0.004 and P = 0.009, respectively). The median time-to-disease recurrence in patients with low MYO1A was 1 y, compared with >9 y in the group of patients with high MYO1A. These results identify MYO1A as a unique tumor-suppressor gene in colorectal cancer and demonstrate that the loss of structural brush border proteins involved in cell polarity are important for tumor development. PMID:22307608

  14. NDRG2 is a candidate tumor-suppressor for oral squamous-cell carcinoma

    SciTech Connect

    Furuta, Hiroshi; Kondo, Yuudai; Nakahata, Shingo; Hamasaki, Makoto; Sakoda, Sumio; Morishita, Kazuhiro

    2010-01-22

    Oral cancer is one of the most common cancers worldwide, and squamous-cell carcinoma (OSCC) is the most common phenotype of oral cancer. Although patients with OSCC have poor survival rates and a high incidence of metastasis, the molecular mechanisms of OSCC development have not yet been elucidated. This study investigated whether N-myc downstream-regulated gene 2 (NDRG2) contributes to the carcinogenesis of OSCC, as NDRG2 is reported to be a candidate tumor-suppressor gene in a wide variety of cancers. The down-regulation of NDRG2 mRNA, which was dependent on promoter methylation, was seen in the majority of OSCC cases and in several cases of precancerous leukoplakia with dysplasia. Induction of NDRG2 expression in an HSC-3/OSCC cell line significantly inhibited cell proliferation and decreased colony formation ability on soft agar. The majority of OSCC cell lines showed an activation of PI3K/Akt signaling, and enforced expression of NDRG2 in HSC-3 cells decreased the level of phosphorylated Akt at Serine 473 (p-Akt). Immunohistochemical p-Akt staining was detected in 56.5% of the OSCC tumors, and 80.4% of the tumors were negative for NDRG2 staining. Moreover, positive p-Akt staining was inversely correlated with decreased NDRG2 expression in OSCC tumors with moderate to poor differentiation (p < 0.005). Therefore, NDRG2 is a candidate tumor-suppressor gene for OSCC development and probably contributes to the tumorigenesis of OSCC partly via the modulation of Akt signaling.

  15. Expression of the tumor suppressor genes NF2, 4.1B, and TSLC1 in canine meningiomas.

    PubMed

    Dickinson, P J; Surace, E I; Cambell, M; Higgins, R J; Leutenegger, C M; Bollen, A W; LeCouteur, R A; Gutmann, D H

    2009-09-01

    Meningiomas are common primary brain tumors in dogs; however, little is known about the molecular genetic mechanisms involved in their tumorigenesis. Several tumor suppressor genes have been implicated in meningioma pathogenesis in humans, including the neurofibromatosis 2 (NF2), protein 4.1B (4.1 B), and tumor suppressor in lung cancer-1 (TSLC1) genes. We investigated the expression of these tumor suppressor genes in a series of spontaneous canine meningiomas using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) (NF2; n = 25) and western blotting (NF2/merlin, 4.1B, TSLC1; n = 30). Decreased expression of 4.1B and TSLC1 expression on western blotting was seen in 6/30 (20%) and in 15/30 (50%) tumors, respectively, with 18/30 (60%) of meningiomas having decreased or absent expression of one or both proteins. NF2 gene expression assessed by western blotting and RT-PCR varied considerably between individual tumors. Complete loss of NF2 protein on western blotting was not seen, unlike 4.1B and TSLC1. Incidence of TSLC1 abnormalities was similar to that seen in human meningiomas, while perturbation of NF2 and 4.1B appeared to be less common than reported for human tumors. No association was observed between tumor grade, subtype, or location and tumor suppressor gene expression based on western blot or RT-PCR. These results suggest that loss of these tumor suppressor genes is a frequent occurrence in canine meningiomas and may be an early event in tumorigenesis in some cases. In addition, it is likely that other, as yet unidentified, genes play an important role in canine meningioma formation and growth.

  16. DNA methylation determines nucleosome occupancy in the 5'-CpG islands of tumor suppressor genes.

    PubMed

    Portela, A; Liz, J; Nogales, V; Setién, F; Villanueva, A; Esteller, M

    2013-11-21

    Promoter CpG island hypermethylation of tumor suppressor genes is an epigenetic hallmark of human cancer commonly associated with nucleosome occupancy and the transcriptional silencing of the neighboring gene. Nucleosomes can determine the underlying DNA methylation status. Herein, we show that the opposite is also true: DNA methylation can determine nucleosome positioning. Using a cancer model and digital nucleosome positioning techniques, we demonstrate that the induction of DNA hypomethylation events by genetic (DNMT1/DNMT3B deficient cells) or drug (a DNA demethylating agent) approaches is associated with the eviction of nucleosomes from previously hypermethylated CpG islands of tumor suppressor genes. Most importantly, the establishment of a stable cell line that restores DNMT1/DNMT3B deficiency shows that nucleosomes reoccupy their positions in de novo methylated CpG islands. Finally, we extend these results to the genomic level, combining a DNA methylation microarray and the nucleosome positioning technique. Using this global approach, we observe the dependency of nucleosome occupancy upon the DNA methylation status. Thus, our results suggest that there is a close association between hypermethylated CpG islands and the presence of nucleosomes, such that each of these epigenetic mechanisms can determine the recruitment of the other.

  17. Tumor Suppressor Genes within Common Fragile Sites Are Active Players in the DNA Damage Response.

    PubMed

    Hazan, Idit; Hofmann, Thomas G; Aqeilan, Rami I

    2016-12-01

    The role of common fragile sites (CFSs) in cancer remains controversial. Two main views dominate the discussion: one suggests that CFS loci are hotspots of genomic instability leading to inactivation of genes encoded within them, while the other view proposes that CFSs are functional units and that loss of the encoded genes confers selective pressure, leading to cancer development. The latter view is supported by emerging evidence showing that expression of a given CFS is associated with genome integrity and that inactivation of CFS-resident tumor suppressor genes leads to dysregulation of the DNA damage response (DDR) and increased genomic instability. These two viewpoints of CFS function are not mutually exclusive but rather coexist; when breaks at CFSs are not repaired accurately, this can lead to deletions by which cells acquire growth advantage because of loss of tumor suppressor activities. Here, we review recent advances linking some CFS gene products with the DDR, genomic instability, and carcinogenesis and discuss how their inactivation might represent a selective advantage for cancer cells.

  18. EZH2 Inhibition Blocks Multiple Myeloma Cell Growth through Upregulation of Epithelial Tumor Suppressor Genes.

    PubMed

    Hernando, Henar; Gelato, Kathy A; Lesche, Ralf; Beckmann, Georg; Koehr, Silke; Otto, Saskia; Steigemann, Patrick; Stresemann, Carlo

    2016-02-01

    Multiple myeloma is a plasma cell malignancy characterized by marked heterogeneous genomic instability including frequent genetic alterations in epigenetic enzymes. In particular, the histone methyltransferase Enhancer of Zeste Homolog 2 (EZH2) is overexpressed in multiple myeloma. EZH2 is the catalytic component of the polycomb repressive complex 2 (PRC2), a master transcriptional regulator of differentiation. EZH2 catalyzes methylation of lysine 27 on histone H3 and its deregulation in cancer has been reported to contribute to silencing of tumor suppressor genes, resulting in a more undifferentiated state, and thereby contributing to the multiple myeloma phenotype. In this study, we propose the use of EZH2 inhibitors as a new therapeutic approach for the treatment of multiple myeloma. We demonstrate that EZH2 inhibition causes a global reduction of H3K27me3 in multiple myeloma cells, promoting reexpression of EZH2-repressed tumor suppressor genes in a subset of cell lines. As a result of this transcriptional activation, multiple myeloma cells treated with EZH2 inhibitors become more adherent and less proliferative compared with untreated cells. The antitumor efficacy of EZH2 inhibitors is also confirmed in vivo in a multiple myeloma xenograft model in mice. Together, our data suggest that EZH2 inhibition may provide a new therapy for multiple myeloma treatment and a promising addition to current treatment options. Mol Cancer Ther; 15(2); 287-98. ©2015 AACR.

  19. NNK, a tobacco-specific carcinogen, inhibits the expression of lysyl oxidase, a tumor suppressor.

    PubMed

    Cheng, Guang; Li, Jianmin; Zheng, Maoguen; Zhao, Yinzhi; Zhou, Jing; Li, Wande

    2014-12-23

    A tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), is believed to contribute to the cancer burden in cigarette smokers. To evaluate NNK effects on the expression of lysyl oxidase (LOX), a tumor suppressor, we examined this enzyme at various levels in NNK-treated rat fetal lung fibroblasts (RFL6). Exposure of cells to NNK reduced levels of steady-states LOX mRNA and new transcript synthesis. NNK inhibited all LOX protein species in a dose-dependent manner. Although 300 µM NNK markedly decreased the level in the 46 kDa preproenzyme, under same conditions, there was no detectable amounts of the 50 kDa proenzyme and the 32 kDa mature enzyme suggesting NNK perturbing the LOX protein processing to its mature form. Moreover, NNK also suppressed LOX activities in conditioned media of treated cells. At the promoter level, NNK enhanced methylation of CpG, but decreased acetylation of histone H3 at the core promoter region of the LOX gene. These results indicated that transcriptional and translational processes of LOX are major targets for NNK. Thus, inactivation of tumor suppressor gene LOX may play a critical role in NNK carcinogenesis.

  20. Newcomers to the WW Domain-Mediated Network of the Hippo Tumor Suppressor Pathway.

    PubMed

    Sudol, Marius

    2010-11-01

    The Hippo tumor suppressor pathway regulates the size of organs by controlling 2 opposing processes: proliferation and apoptosis. The pathway was originally defined in Drosophila, but it is well conserved in mammals. One of the unique features of Hippo signaling is the unusually wide occurrence of WW domains and its cognate PPxY ligand motifs within components of this pathway. Recently, it was proposed that the prevalence of WW domain-mediated complexes in the Hippo signaling pathway should facilitate its molecular analysis and help in the identification of new components of the Hippo-centered network. Indeed, several new members of the Hippo pathway, which form functional complexes with WW domains of YAP and TAZ effectors, were recently described. We focus here on 2 families of such proteins, angiomotins and SMADs, plus 1 regulatory factor, WBP-2, which together shed new light on the rapidly expanding Hippo network. Since the Hippo pathway acts as a tumor suppressor pathway, the complexes described here, which assemble on WW domains of YAP and TAZ, represent potential targets of cancer therapy.

  1. Histone deacetylase 3 inhibits new tumor suppressor gene DTWD1 in gastric cancer

    PubMed Central

    Ma, Yanning; Yue, Yongfang; Pan, Min; Sun, Jie; Chu, Jue; Lin, Xiaoying; Xu, Wenxia; Feng, Lifeng; Chen, Yan; Chen, Dingwei; Shin, Vivian Y; Wang, Xian; Jin, Hongchuan

    2015-01-01

    Cancer epigenetics plays an important role in the pathogenesis of many cancers including gastric cancer. Histone deacetylases (HDACs) emerge as exciting therapeutic targets for cancer treatment and prevention. In this study, we identified DTWD1 as one of the 122 genes upregulated after treatment of trichostatin A (TSA) in two gastric cancer cell lines. Moreover, DTWD1 was downregulated in gastric cancer cell lines and primary gastric carcinoma tissues. It was further identified as the new target of p53. Then we revealed that HDAC3 downregulated DTWD1 by disrupting the interaction of p53 with DTWD1 promoter. Furthermore, DTWD1 functioned as a tumor suppressor by downregulating cyclin B1 expression to inhibit proliferation. In summary, as the new p53 target gene, DTWD1 was downregulated in gastric cancer by HDAC3 and acted as a novel tumor suppressor gene. Specific inhibitors of HDAC3 might be a new approach for gastric cancer treatment by activating DTWD1 expression. PMID:25973305

  2. The LATS2 tumor suppressor inhibits SREBP and suppresses hepatic cholesterol accumulation.

    PubMed

    Aylon, Yael; Gershoni, Anat; Rotkopf, Ron; Biton, Inbal E; Porat, Ziv; Koh, Anna P; Sun, Xiaochen; Lee, Youngmin; Fiel, Maria-Isabel; Hoshida, Yujin; Friedman, Scott L; Johnson, Randy L; Oren, Moshe

    2016-04-01

    The Hippo signaling pathway is a major regulator of organ size. In the liver, Hippo pathway deregulation promotes hyperplasia and hepatocellular carcinoma primarily through hyperactivation of its downstream effector, YAP. The LATS2 tumor suppressor is a core member of the Hippo pathway. A screen for LATS2-interacting proteins in liver-derived cells identified the transcription factor SREBP2, master regulator of cholesterol homeostasis. LATS2 down-regulation caused SREBP activation and accumulation of excessive cholesterol. Likewise, mice harboring liver-specific Lats2 conditional knockout (Lats2-CKO) displayed constitutive SREBP activation and overexpressed SREBP target genes and developed spontaneous fatty liver disease. Interestingly, the impact of LATS2 depletion on SREBP-mediated transcription was clearly distinct from that of YAP overexpression. When challenged with excess dietary cholesterol, Lats2-CKO mice manifested more severe liver damage than wild-type mice. Surprisingly, apoptosis, inflammation, and fibrosis were actually attenuated relative to wild-type mice, in association with impaired p53 activation. Subsequently, Lats2-CKO mice failed to recover effectively from cholesterol-induced damage upon return to a normal diet. Additionally, decreased LATS2 mRNA in association with increased SREBP target gene expression was observed in a subset of human nonalcoholic fatty liver disease cases. Together, these findings further highlight the tight links between tumor suppressors and metabolic homeostasis.

  3. Tumor Suppressor Genes within Common Fragile Sites Are Active Players in the DNA Damage Response

    PubMed Central

    Hazan, Idit; Hofmann, Thomas G.; Aqeilan, Rami I.

    2016-01-01

    The role of common fragile sites (CFSs) in cancer remains controversial. Two main views dominate the discussion: one suggests that CFS loci are hotspots of genomic instability leading to inactivation of genes encoded within them, while the other view proposes that CFSs are functional units and that loss of the encoded genes confers selective pressure, leading to cancer development. The latter view is supported by emerging evidence showing that expression of a given CFS is associated with genome integrity and that inactivation of CFS-resident tumor suppressor genes leads to dysregulation of the DNA damage response (DDR) and increased genomic instability. These two viewpoints of CFS function are not mutually exclusive but rather coexist; when breaks at CFSs are not repaired accurately, this can lead to deletions by which cells acquire growth advantage because of loss of tumor suppressor activities. Here, we review recent advances linking some CFS gene products with the DDR, genomic instability, and carcinogenesis and discuss how their inactivation might represent a selective advantage for cancer cells. PMID:27977694

  4. Tumor-suppressor Genes, Cell Cycle Regulatory Checkpoints, and the Skin

    PubMed Central

    Velez, Ana Maria Abreu; Howard, Michael S.

    2015-01-01

    The cell cycle (or cell-division cycle) is a series of events that take place in a cell, leading to its division and duplication. Cell division requires cell cycle checkpoints (CPs) that are used by the cell to both monitor and regulate the progress of the cell cycle. Tumor-suppressor genes (TSGs) or antioncogenes are genes that protect the cell from a single event or multiple events leading to cancer. When these genes mutate, the cell can progress to a cancerous state. We aimed to perform a narrative review, based on evaluation of the manuscripts published in MEDLINE-indexed journals using the Medical Subject Headings (MeSH) terms “tumor suppressor's genes,” “skin,” and “cell cycle regulatory checkpoints.” We aimed to review the current concepts regarding TSGs, CPs, and their association with selected cutaneous diseases. It is important to take into account that in some cell cycle disorders, multiple genetic abnormalities may occur simultaneously. These abnormalities may include intrachromosomal insertions, unbalanced division products, recombinations, reciprocal deletions, and/or duplication of the inserted segments or genes; thus, these presentations usually involve several genes. Due to their complexity, these disorders require specialized expertise for proper diagnosis, counseling, personal and family support, and genetic studies. Alterations in the TSGs or CP regulators may occur in many benign skin proliferative disorders, neoplastic processes, and genodermatoses. PMID:26110128

  5. The LATS2 tumor suppressor inhibits SREBP and suppresses hepatic cholesterol accumulation

    PubMed Central

    Aylon, Yael; Gershoni, Anat; Rotkopf, Ron; Biton, Inbal E.; Porat, Ziv; Koh, Anna P.; Sun, Xiaochen; Lee, Youngmin; Fiel, Maria-Isabel; Hoshida, Yujin; Friedman, Scott L.; Johnson, Randy L.; Oren, Moshe

    2016-01-01

    The Hippo signaling pathway is a major regulator of organ size. In the liver, Hippo pathway deregulation promotes hyperplasia and hepatocellular carcinoma primarily through hyperactivation of its downstream effector, YAP. The LATS2 tumor suppressor is a core member of the Hippo pathway. A screen for LATS2-interacting proteins in liver-derived cells identified the transcription factor SREBP2, master regulator of cholesterol homeostasis. LATS2 down-regulation caused SREBP activation and accumulation of excessive cholesterol. Likewise, mice harboring liver-specific Lats2 conditional knockout (Lats2-CKO) displayed constitutive SREBP activation and overexpressed SREBP target genes and developed spontaneous fatty liver disease. Interestingly, the impact of LATS2 depletion on SREBP-mediated transcription was clearly distinct from that of YAP overexpression. When challenged with excess dietary cholesterol, Lats2-CKO mice manifested more severe liver damage than wild-type mice. Surprisingly, apoptosis, inflammation, and fibrosis were actually attenuated relative to wild-type mice, in association with impaired p53 activation. Subsequently, Lats2-CKO mice failed to recover effectively from cholesterol-induced damage upon return to a normal diet. Additionally, decreased LATS2 mRNA in association with increased SREBP target gene expression was observed in a subset of human nonalcoholic fatty liver disease cases. Together, these findings further highlight the tight links between tumor suppressors and metabolic homeostasis. PMID:27013235

  6. The tumor suppressor Rb critically regulates starvation-induced stress response in C. elegans.

    PubMed

    Cui, Mingxue; Cohen, Max L; Teng, Cindy; Han, Min

    2013-06-03

    How animals coordinate gene expression in response to starvation is an outstanding problem closely linked to aging, obesity, and cancer. Newly hatched Caenorhabditis elegans respond to food deprivation by halting development and promoting long-term survival (L1 diapause), thereby providing an excellent model for the study of starvation response. Through a genetic search, we have discovered that the tumor suppressor Rb critically promotes survival during L1 diapause and most likely does so by regulating the expression of genes in both insulin-IGF-1 signaling (IIS)-dependent and -independent pathways mainly in neurons and the intestine. Global gene expression analyses suggested that Rb maintains the "starvation-induced" transcriptome and represses the "refeeding-induced" transcriptome, including the repression of many pathogen-, toxin-, and oxidative-stress-inducible and metabolic genes, as well as the activation of many other stress-resistant genes, mitochondrial respiratory chain genes, and potential IIS receptor antagonists. Notably, the majority of genes dysregulated in starved L1 Rb(-) animals were not found to be dysregulated in fed conditions. Altogether, these findings identify Rb as a critical regulator of the starvation response and suggest a link between functions of tumor suppressors and starvation survival. These results may provide mechanistic insights into why cancer cells are often hypersensitive to starvation treatment.

  7. Functional conservation of the human EXT1 tumor suppressor gene and its Drosophila homolog tout velu.

    PubMed

    Dasgupta, Ujjaini; Dixit, Bharat L; Rusch, Melissa; Selleck, Scott; The, Inge

    2007-08-01

    Heparan sulfate proteoglycans play a vital role in signaling of various growth factors in both Drosophila and vertebrates. In Drosophila, mutations in the tout velu (ttv) gene, a homolog of the mammalian EXT1 tumor suppressor gene, leads to abrogation of glycosaminoglycan (GAG) biosynthesis. This impairs distribution and signaling activities of various morphogens such as Hedgehog (Hh), Wingless (Wg), and Decapentaplegic (Dpp). Mutations in members of the exostosin (EXT) gene family lead to hereditary multiple exostosis in humans leading to bone outgrowths and tumors. In this study, we provide genetic and biochemical evidence that the human EXT1 (hEXT1) gene is conserved through species and can functionally complement the ttv mutation in Drosophila. The hEXT1 gene was able to rescue a ttv null mutant to adulthood and restore GAG biosynthesis.

  8. The putative tumor suppressor gene EphA7 is a novel BMI-1 target

    PubMed Central

    Jagemann, Lucas; Nolbrant, Sara; Leefa, Isabelle V.; Offen, Nils; Miharada, Kenichi; Lang, Stefan; Artner, Isabella; Nuber, Ulrike A.

    2016-01-01

    Bmi1 was originally identified as a gene that contributes to the development of mouse lymphoma by inhibiting MYC-induced apoptosis through repression of Ink4a and Arf. It codes for the Polycomb group protein BMI-1 and acts primarily as a transcriptional repressor via chromatin modifications. Although it binds to a large number of genomic regions, the direct BMI-1 target genes described so far do not explain the full spectrum of BMI-1-mediated effects. Here we identify the putative tumor suppressor gene EphA7 as a novel direct BMI-1 target in neural cells and lymphocytes. EphA7 silencing has been reported in several different human tumor types including lymphomas, and our data suggest BMI1 overexpression as a novel mechanism leading to EphA7 inactivation via H3K27 trimethylation and DNA methylation. PMID:27533460

  9. Inhibition of pluripotency networks by the Rb tumor suppressor restricts reprogramming and tumorigenesis.

    PubMed

    Kareta, Michael S; Gorges, Laura L; Hafeez, Sana; Benayoun, Bérénice A; Marro, Samuele; Zmoos, Anne-Flore; Cecchini, Matthew J; Spacek, Damek; Batista, Luis F Z; O'Brien, Megan; Ng, Yi-Han; Ang, Cheen Euong; Vaka, Dedeepya; Artandi, Steven E; Dick, Frederick A; Brunet, Anne; Sage, Julien; Wernig, Marius

    2015-01-08

    Mutations in the retinoblastoma tumor suppressor gene Rb are involved in many forms of human cancer. In this study, we investigated the early consequences of inactivating Rb in the context of cellular reprogramming. We found that Rb inactivation promotes the reprogramming of differentiated cells to a pluripotent state. Unexpectedly, this effect is cell cycle independent, and instead reflects direct binding of Rb to pluripotency genes, including Sox2 and Oct4, which leads to a repressed chromatin state. More broadly, this regulation of pluripotency networks and Sox2 in particular is critical for the initiation of tumors upon loss of Rb in mice. These studies therefore identify Rb as a global transcriptional repressor of pluripotency networks, providing a molecular basis for previous reports about its involvement in cell fate pliability, and implicate misregulation of pluripotency factors such as Sox2 in tumorigenesis related to loss of Rb function.

  10. Gastrokines: stomach-specific proteins with putative homeostatic and tumor suppressor roles.

    PubMed

    Menheniott, Trevelyan R; Kurklu, Bayzar; Giraud, Andrew S

    2013-01-15

    During the past decade, a new family of stomach-specific proteins has been recognized. Known as "gastrokines" (GKNs), these secreted proteins are products of gastric mucus-producing cell lineages. GKNs are highly conserved in physical structure, and emerging data point to convergent functions in the modulation of gastric mucosal homeostasis and inflammation. While GKNs are highly prevalent in the normal stomach, frequent loss of GKN expression in gastric cancers, coupled with established antiproliferative activity, suggests putative tumor suppressor roles. Conversely, ectopic expression of GKNs in reparative lesions of Crohn's disease alludes to additional activity in epithelial wound healing and/or repair. Modes of action remain unsolved, but the recent demonstration of a GKN2-trefoil factor 1 heterodimer implicates functional interplay with trefoil factors. This review aims to provide a historical account of GKN biology and encapsulate the rapidly accumulating evidence supporting roles in gastric epithelial homeostasis and tumor suppression.

  11. MicroRNA-106b regulates the tumor suppressor RUNX3 in laryngeal carcinoma cells.

    PubMed

    Xu, Ying; Wang, Kai; Gao, Wei; Zhang, Chunming; Huang, Fuhui; Wen, Shuxin; Wang, Binquan

    2013-10-01

    Our study focuses on a set of laryngeal tumors that show reduced RUNX3 expression in the absence of transcriptional silencing of tumor suppressor gene RUNX3 by aberrant methylation of CpG islands. We report that the loss of expression of RUNX3 correlates with up-regulation of miR-106b in human laryngeal carcinoma tissue. The downregulation of RUNX3 is mediated by miR-106b through binding of its 3'UTR. Moreover, miR-106b can promote the proliferation and invasion of laryngeal carcinoma cells by directly targeting RUNX3, and RUXN3 knockdown can abolish this phenotype. These results shed a new insight into the mechanism of miRNA regulation in laryngeal carcinoma.

  12. Tricyclic guanidine alkaloids from the marine sponge Acanthella cavernosa that stabilize the tumor suppressor PDCD4.

    PubMed

    Grkovic, Tanja; Blees, Johanna S; Bayer, Magdalena M; Colburn, Nancy H; Thomas, Cheryl L; Henrich, Curtis J; Peach, Megan L; McMahon, James B; Schmid, Tobias; Gustafson, Kirk R

    2014-08-21

    A cell-based high-throughput screen that assessed the cellular stability of a tumor suppressor protein PDCD4 (Programmed cell death 4) was used to identify a new guanidine-containing marine alkaloid mirabilin K (3), as well as the known compounds mirabilin G (1) and netamine M (2). The structures of these tricyclic guanidine alkaloids were established from extensive spectroscopic analyses. Compounds 1 and 2 inhibited cellular degradation of PDCD4 with EC50 values of 1.8 μg/mL and 2.8 μg/mL, respectively. Mirabilin G (1) and netamine M (2) are the first marine natural products reported to stabilize PDCD4 under tumor promoting conditions.

  13. Tricyclic Guanidine Alkaloids from the Marine Sponge Acanthella cavernosa that Stabilize the Tumor Suppressor PDCD4

    PubMed Central

    Grkovic, Tanja; Blees, Johanna S.; Bayer, Magdalena M.; Colburn, Nancy H.; Thomas, Cheryl L.; Henrich, Curtis J.; Peach, Megan L.; McMahon, James B.; Schmid, Tobias; Gustafson, Kirk R.

    2014-01-01

    A cell-based high-throughput screen that assessed the cellular stability of a tumor suppressor protein PDCD4 (Programmed cell death 4) was used to identify a new guanidine-containing marine alkaloid mirabilin K (3), as well as the known compounds mirabilin G (1) and netamine M (2). The structures of these tricyclic guanidine alkaloids were established from extensive spectroscopic analyses. Compounds 1 and 2 inhibited cellular degradation of PDCD4 with EC50 values of 1.8 μg/mL and 2.8 μg/mL, respectively. Mirabilin G (1) and netamine M (2) are the first marine natural products reported to stabilize PDCD4 under tumor promoting conditions. PMID:25196934

  14. NF1 is a tumor suppressor in neuroblastoma that determines retinoic acid response and disease outcome

    PubMed Central

    Hölzel, Michael; Huang, Sidong; Koster, Jan; Øra, Ingrid; Lakeman, Arjan; Caron, Huib; Nijkamp, Wouter; Xie, Jing; Callens, Tom; Asgharzadeh, Shahab; Seeger, Robert C.; Messiaen, Ludwine; Versteeg, Rogier; Bernards, René

    2010-01-01

    Summary Retinoic acid (RA) induces differentiation of neuroblastoma cells in vitro and is used with variable success to treat aggressive forms of this disease. This variability in clinical response to RA is enigmatic, as no mutations in components of the RA signaling cascade have been found. Using a large-scale RNAi genetic screen, we identify crosstalk between the tumor suppressor NF1 and retinoic acid induced differentiation in neuroblastoma. Loss of NF1 activates RAS-MEK signaling, which in turn represses ZNF423, a critical transcriptional co-activator of the retinoic acid receptors. Neuroblastomas with low levels of both NF1 and ZNF423 have extremely poor outcome. We find NF1 mutations in neuroblastoma cell lines and in primary tumors. Inhibition of MEK signaling downstream of NF1 restores responsiveness to RA, suggesting a therapeutic strategy to overcome RA resistance in NF1 deficient neuroblastomas. PMID:20655465

  15. Tumor suppressor gene E-cadherin and its role in normal and malignant cells

    PubMed Central

    Pećina-Šlaus, Nives

    2003-01-01

    E-cadherin tumor suppressor genes are particularly active area of research in development and tumorigenesis. The calcium-dependent interactions among E-cadherin molecules are critical for the formation and maintenance of adherent junctions in areas of epithelial cell-cell contact. Loss of E-cadherin-mediated-adhesion characterises the transition from benign lesions to invasive, metastatic cancer. Nevertheless, there is evidence that E-cadherins may also play a role in the wnt signal transduction pathway, together with other key molecules involved in it, such as beta-catenins and adenomatous poliposis coli gene products. The structure and function of E-cadherin, gene and protein, in normal as well as in tumor cells are reviewed in this paper. PMID:14613514

  16. An identity crisis for fps/fes: oncogene or tumor suppressor?

    PubMed

    Sangrar, Waheed; Zirgnibl, Ralph A; Gao, Yan; Muller, William J; Jia, Zongchao; Greer, Peter A

    2005-05-01

    Fps/Fes proteins were among the first members of the protein tyrosine kinase family to be characterized as dominant-acting oncoproteins. Addition of retroviral GAG sequences or other experimentally induced mutations activated the latent transforming potential of Fps/Fes. However, activating mutations in fps/fes had not been found in human tumors until recently, when mutational analysis of a panel of colorectal cancers identified four somatic mutations in sequences encoding the Fps/Fes kinase domain. Here, we report biochemical and theoretical structural analysis demonstrating that three of these mutations result in inactivation, not activation, of Fps/Fes, whereas the fourth mutation compromised in vivo activity. These results did not concur with a classic dominant-acting oncogenic role for fps/fes involving activating somatic mutations but instead raised the possibility that inactivating fps/fes mutations might promote tumor progression in vivo. Consistent with this, we observed that tumor onset in a mouse model of breast epithelial cancer occurred earlier in mice targeted with either null or kinase-inactivating fps/fes mutations. Furthermore, a fps/fes transgene restored normal tumor onset kinetics in targeted fps/fes null mice. These data suggest a novel and unexpected tumor suppressor role for Fps/Fes in epithelial cells.

  17. Loss of RasGAP Tumor Suppressors Underlies the Aggressive Nature of Luminal B Breast Cancers.

    PubMed

    Olsen, Sarah Naomi; Wronski, Ania; Castaño, Zafira; Dake, Benjamin; Malone, Clare; De Raedt, Thomas; Enos, Miriam; DeRose, Yoko S; Zhou, Wenhui; Guerra, Stephanie; Loda, Massimo; Welm, Alana; Partridge, Ann H; McAllister, Sandra S; Kuperwasser, Charlotte; Cichowski, Karen

    2017-02-01

    Luminal breast cancers are typically estrogen receptor-positive and generally have the best prognosis. However, a subset of luminal tumors, namely luminal B cancers, frequently metastasize and recur. Unfortunately, the causal events that drive their progression are unknown, and therefore it is difficult to identify individuals who are likely to relapse and should receive escalated treatment. Here, we identify a bifunctional RasGAP tumor suppressor whose expression is lost in almost 50% of luminal B tumors. Moreover, we show that two RasGAP genes are concomitantly suppressed in the most aggressive luminal malignancies. Importantly, these genes cooperatively regulate two major oncogenic pathways, RAS and NF-κB, through distinct domains, and when inactivated drive the metastasis of luminal tumors in vivo Finally, although the cooperative effects on RAS drive invasion, NF-κB activation triggers epithelial-to-mesenchymal transition and is required for metastasis. Collectively, these studies reveal important mechanistic insight into the pathogenesis of luminal B tumors and provide functionally relevant prognostic biomarkers that may guide treatment decisions.

  18. The p53 tumor suppressor protein protects against chemotherapeutic stress and apoptosis in human medulloblastoma cells

    PubMed Central

    Parasido, Erika; Tricoli, Lucas; Sivakumar, Angiela; Mikhaiel, John P.; Yenugonda, Venkata; Rodriguez, Olga C.; Karam, Sana D.; Rood, Brian R.; Avantaggiati, Maria Laura; Albanese, Chris

    2015-01-01

    Medulloblastoma (MB), a primitive neuroectodermal tumor, is the most common malignant childhood brain tumor and remains incurable in about a third of patients. Currently, survivors carry a significant burden of late treatment effects. The p53 tumor suppressor protein plays a crucial role in influencing cell survival in response to cellular stress and while the p53 pathway is considered a key determinant of anti-tumor responses in many tumors, its role in cell survival in MB is much less well defined. Herein, we report that the experimental drug VMY-1-103 acts through induction of a partial DNA damage-like response as well induction of non-survival autophagy. Surprisingly, the genetic or chemical silencing of p53 significantly enhanced the cytotoxic effects of both VMY and the DNA damaging drug, doxorubicin. The inhibition of p53 in the presence of VMY revealed increased late stage apoptosis, increased DNA fragmentation and increased expression of genes involved in apoptosis, including CAPN12 and TRPM8, p63, p73, BIK, EndoG, CIDEB, P27Kip1 and P21cip1. These data provide the groundwork for additional studies on VMY as a therapeutic drug and support further investigations into the intriguing possibility that targeting p53 function may be an effective means of enhancing clinical outcomes in MB. PMID:26540407

  19. Rnd3 in Cancer: A Review of the Evidence for Tumor Promoter or Suppressor.

    PubMed

    Paysan, Lisa; Piquet, Léo; Saltel, Frédéric; Moreau, Violaine

    2016-11-01

    Rho-GTPases are members of the Ras superfamily of small GTPases and are general modulators of important cellular processes in tumor biology such as migration and proliferation. Among these proteins, Rnd3/RhoE, an atypical Rho-GTPase devoid of GTP hydrolytic activity, has recently been studied for its putative role in tumorigenesis. Indeed, Rnd3 is implicated in processes, such as proliferation and migration, whose deregulation is linked to cancer development and metastasis. The aim of this review is to provide an overview of the data surrounding Rnd3 deregulation in cancers, its origin, and consequences. Presented here is a comprehensive account of the expression status and biological output obtained in prostate, liver, stomach, colon, lung, and brain cancers as well as in melanoma and squamous cell carcinoma. Although there appears to be no general consensus about Rnd3 expression in cancers as this protein is differently altered according to the tumor context, these alterations overwhelmingly favor a protumorigenic role. Thus, depending on the tumor type, it may behave either as a tumor suppressor or as a tumor promoter. Importantly, the deregulation of Rnd3, in most cases, is linked to patient poor outcome.

  20. mTOR masters monocytic myeloid-derived suppressor cells in mice with allografts or tumors.

    PubMed

    Wu, Tingting; Zhao, Yang; Wang, Hao; Li, Yang; Shao, Lijuan; Wang, Ruoyu; Lu, Jun; Yang, Zhongzhou; Wang, Junjie; Zhao, Yong

    2016-02-01

    CD11b(+) Gr1(+) myeloid-derived suppressor cells (MDSCs) play critical roles in controlling the processes of tumors, infections, autoimmunity and graft rejection. Immunosuppressive drug rapamycin (RPM), targeting on the key cellular metabolism molecule mTOR, is currently used in clinics to treat patients with allo-grafts, autoimmune diseases and tumors. However, the effect of RPM on MDSCs has not been studied. RPM significantly decreases the cell number and the immunosuppressive ability on T cells of CD11b(+) Ly6C(high) monocytic MDSCs (M-MDSCs) in both allo-grafts-transplanted and tumor-bearing mice respectively. Mice with a myeloid-specific deletion of mTOR have poor M-MDSCs after grafting with allo-skin tissue or a tumor. Grafting of allo-skin or tumors significantly activates glycolysis pathways in myeloid precursor cells in bone marrow, which is inhibited by RPM or mTOR deletion. 2-deoxyglucose (2-DG), an inhibitor of the glycolytic pathway, inhibits M-MDSC differentiation from precursors, while enhancing glycolysis by metformin significantly rescues the RPM-caused deficiency of M-MDSCs. Therefore, we offer evidence supporting that mTOR is an intrinsic factor essential for the differentiation and immunosuppressive function of M-MDSCs and that these metabolism-relevant medicines may impact MDSCs-mediated immunosuppression or immune tolerance induction, which is of considerable clinical importance in treating graft rejection, autoimmune diseases and cancers.

  1. Tumor-induced myeloid deviation: when myeloid-derived suppressor cells meet tumor-associated macrophages.

    PubMed

    Ugel, Stefano; De Sanctis, Francesco; Mandruzzato, Susanna; Bronte, Vincenzo

    2015-09-01

    The generation of an inflammatory environment is favorable and often decisive for the growth of both primary tumors and metastases. Tumor cells either express membrane molecules or release tumor-derived soluble factors able to alter myelopoiesis. Tumor-reprogrammed myeloid cells not only create a tolerogenic environment by blocking T cell functions and proliferation, but also directly drive tumor growth by promoting cancer stemness, angiogenesis, stroma deposition, epithelial-to-mesenchymal transition, and metastasis formation. In this Review, we discuss the interplay between immunosuppressive and protumoral myeloid cells and detail their immune-regulatory mechanisms, the molecular pathways involved in their differentiation, as well as their potential role as prognostic and diagnostic biomarkers and prospective targets for innovative approaches to treat tumor-bearing hosts.

  2. Tumor-induced myeloid deviation: when myeloid-derived suppressor cells meet tumor-associated macrophages

    PubMed Central

    Ugel, Stefano; De Sanctis, Francesco; Mandruzzato, Susanna; Bronte, Vincenzo

    2015-01-01

    The generation of an inflammatory environment is favorable and often decisive for the growth of both primary tumors and metastases. Tumor cells either express membrane molecules or release tumor-derived soluble factors able to alter myelopoiesis. Tumor-reprogrammed myeloid cells not only create a tolerogenic environment by blocking T cell functions and proliferation, but also directly drive tumor growth by promoting cancer stemness, angiogenesis, stroma deposition, epithelial-to-mesenchymal transition, and metastasis formation. In this Review, we discuss the interplay between immunosuppressive and protumoral myeloid cells and detail their immune-regulatory mechanisms, the molecular pathways involved in their differentiation, as well as their potential role as prognostic and diagnostic biomarkers and prospective targets for innovative approaches to treat tumor-bearing hosts. PMID:26325033

  3. Compositional features are potentially involved in the regulation of gene expression of tumor suppressor genes in human tissues.

    PubMed

    Hajjari, Mohammadreza; Khoshnevisan, Atefeh; Behmanesh, Mehrdad

    2014-12-15

    Different mechanisms regulate the expression level of tissue specific genes in human. Here we report some compositional features such as codon usage bias, amino acid usage bias, codon frequency, and base composition which may be potentially related to mRNA amount of tissue specific tumor suppressor genes. Our findings support the possibility that structural elements in gene and protein may play an important role in the regulation of tumor suppressor genes, development, and tumorigenesis. The data presented here can open broad vistas in the understanding and treatment of a variety of human malignancies.

  4. Circulating and Tumor-Infiltrating Myeloid-Derived Suppressor Cells in Patients with Colorectal Carcinoma

    PubMed Central

    Wu, Liangliang; Zhang, Meng; Li, Wei; Ding, Jianhua; Zhu, Jun; Wei, Huafeng; Zhao, Ke

    2013-01-01

    Myeloid-derived suppressor cells (MDSCs) are a heterogeneous family of myeloid cells that suppress T cell immunity in tumor-bearing hosts. In patients with colon cancer, MDSCs have recently been described as Lin−/lowHLA-DR−CD11b+CD33+ cells correlating with cancer stage, metastasis and chemotherapy response. To learn in more detail the dynamic change and clinical relevance of circulating and tumor-infiltrating Lin−/lowHLA-DR−CD11b+CD33+ MDSC in colorectal cancer, we harvested the blood from 64 patients with varying stage of colorectal cancer and tumor and matched paraneoplastic tissues from 5 patients with advanced colorectal cancer, subjected them to multicolor flow cytometric analysis of percentage, absolute number and phenotype of MDSC and finally characterized their immunosuppressive functions. Our results demonstrate that peripheral blood from colorectal cancer patients contains markedly increased percentage and absolute number of Lin−/lowHLA-DR−CD11b+CD33+ MDSCs compared with healthy individuals, and this increase is closely correlated with clinical cancer stage and tumor metastasis but not primary tumor size and serum concentrations of cancer biomarker. A similar increase of MDSCs was also observed in the tumor tissues. Phenotyping MDSCs shows that they express high CD13 and CD39, low CD115, CD117, CD124 and PD-L1, and devoid of CD14, CD15 and CD66b, reminiscent of precursor myeloid cells. MDSCs from cancer patients but not healthy donors have the immunosuppressive activity and were able to inhibit in vitro autologous T-cell proliferation. Collectively, this study substantiates the presence of increased immunosuppressive circulating and tumor-resident Lin−/lowHLA-DR−CD11b+CD33+ MDSCs in patients with colorectal cancers correlating with cancer stage and metastasis, and suggests that pharmacologic blockade of MDSCs should be considered in future clinical trials. PMID:23437326

  5. The WWOX tumor suppressor is essential for postnatal survival and normal bone metabolism.

    PubMed

    Aqeilan, Rami I; Hassan, Mohammad Q; de Bruin, Alain; Hagan, John P; Volinia, Stefano; Palumbo, Titziana; Hussain, Sadiq; Lee, Suk-Hee; Gaur, Tripti; Stein, Gary S; Lian, Jane B; Croce, Carlo M

    2008-08-01

    The WW domain-containing oxidoreductase (WWOX) gene encodes a tumor suppressor. We have previously shown that targeted ablation of the Wwox gene in mouse increases the incidence of spontaneous and chemically induced tumors. To investigate WWOX function in vivo, we examined Wwox-deficient (Wwox(-/-)) mice for phenotypical abnormalities. Wwox(-/-) mice are significantly reduced in size, die at the age of 2-3 weeks, and suffer a metabolic disorder that affects the skeleton. Wwox(-/-) mice exhibit a delay in bone formation from a cell autonomous defect in differentiation beginning at the mineralization stage shown in calvarial osteoblasts ex vivo and supported by significantly decreased bone formation parameters in Wwox(-/-) mice by microcomputed tomography analyses. Wwox(-/-) mice develop metabolic bone disease, as a consequence of reduced serum calcium, hypoproteinuria, and hypoglycemia leading to increased osteoclast activity and bone resorption. Interestingly, we find WWOX physically associates with RUNX2, the principal transcriptional regulator of osteoblast differentiation, and on osteocalcin chromatin. We show WWOX functionally suppresses RUNX2 transactivation ability in osteoblasts. In breast cancer MDA-MB-242 cells that lack endogenous WWOX protein, restoration of WWOX expression inhibited Runx2 and RUNX2 target genes related to metastasis. Affymetrix mRNA profiling revealed common gene targets in multiple tissues. In Wwox(-/-) mice, genes related to nucleosome assembly and cell growth genes were down-regulated, and negative regulators of skeletal metabolism exhibited increased expression. Our results demonstrate an essential requirement for the WWOX tumor suppressor in postnatal survival, growth, and metabolism and suggest a central role for WWOX in regulation of bone tissue formation.

  6. The tumor suppressor HHEX inhibits axon growth when prematurely expressed in developing central nervous system neurons

    PubMed Central

    Simpson, Matthew T; Venkatesh, Ishwariya; Callif, Ben L; Thiel, Laura K; Coley, Denise M; Winsor, Kristen N; Wang, Zimei; Kramer, Audra A; Lerch, Jessica K; Blackmore, Murray G

    2015-01-01

    Neurons in the embryonic and peripheral nervous system respond to injury by activating transcriptional programs supportive of axon growth, ultimately resulting in functional recovery. In contrast, neurons in the adult central nervous system (CNS) possess a limited capacity to regenerate axons after injury, fundamentally constraining repair. Activating pro-regenerative gene expression in CNS neurons is a promising therapeutic approach, but progress is hampered by incomplete knowledge of the relevant transcription factors. An emerging hypothesis is that factors implicated in cellular growth and motility outside the nervous system may also control axon growth in neurons. We therefore tested sixty-nine transcription factors, previously identified as possessing tumor suppressive or oncogenic properties in non-neuronal cells, in assays of neurite outgrowth. This screen identified YAP1 and E2F1 as enhancers of neurite outgrowth, and PITX1, RBM14, ZBTB16, and HHEX as inhibitors. Follow-up experiments focused on the tumor suppressor HHEX, one of the strongest growth inhibitors. HHEX is widely expressed in adult CNS neurons, including corticospinal tract neurons after spinal injury, but is present in only trace amounts in immature cortical neurons and adult peripheral neurons. HHEX overexpression in early postnatal cortical neurons reduced both initial axonogenesis and the rate of axon elongation, and domain deletion analysis strongly implicated transcriptional repression as the underlying mechanism. These findings suggest a role for HHEX in restricting axon growth in the developing CNS, and substantiate the hypothesis that previously identified oncogenes and tumor suppressors can play conserved roles in axon extension. PMID:26306672

  7. ECRG4 is a candidate tumor suppressor gene frequently hypermethylated in colorectal carcinoma and glioma

    PubMed Central

    2009-01-01

    Background Cancer cells display widespread changes in DNA methylation that may lead to genetic instability by global hypomethylation and aberrant silencing of tumor suppressor genes by focal hypermethylation. In turn, altered DNA methylation patterns have been used to identify putative tumor suppressor genes. Methods In a methylation screening approach, we identified ECRG4 as a differentially methylated gene. We analyzed different cancer cells for ECRG4 promoter methylation by COBRA and bisulfite sequencing. Gene expression analysis was carried out by semi-quantitative RT-PCR. The ECRG4 coding region was cloned and transfected into colorectal carcinoma cells. Cell growth was assessed by MTT and BrdU assays. ECRG4 localization was analyzed by fluorescence microscopy and Western blotting after transfection of an ECRG4-eGFP fusion gene. Results We found a high frequency of ECRG4 promoter methylation in various cancer cell lines. Remarkably, aberrant methylation of ECRG4 was also found in primary human tumor tissues, including samples from colorectal carcinoma and from malignant gliomas. ECRG4 hypermethylation associated strongly with transcriptional silencing and its expression could be re-activated in vitro by demethylating treatment with 5-aza-2'-deoxycytidine. Overexpression of ECRG4 in colorectal carcinoma cells led to a significant decrease in cell growth. In transfected cells, ECRG4 protein was detectable within the Golgi secretion machinery as well as in the culture medium. Conclusions ECRG4 is silenced via promoter hypermethylation in different types of human cancer cells. Its gene product may act as inhibitor of cell proliferation in colorectal carcinoma cells and may play a role as extracellular signaling molecule. PMID:20017917

  8. Peperomin E reactivates silenced tumor suppressor genes in lung cancer cells by inhibition of DNA methyltransferase.

    PubMed

    Wang, Xin-Zhi; Cheng, Ying; Wang, Kui-Long; Liu, Rui; Yang, Xiao-Lin; Wen, Hong-Mei; Chai, Chuan; Liang, Jing-Yu; Wu, Hao

    2016-10-01

    Advanced lung cancer has poor prognosis owing to its low sensitivity to current chemotherapy agents. Therefore, discovery of new therapeutic agents is urgently needed. In this study, we investigated the antitumor effects of peperomin E, a secolignan isolated from Peperomia dindygulensis, a frequently used Chinese folk medicine for lung cancer treatment. The results indicate that peperomin E has antiproliferative effects, promoting apoptosis and cell cycle arrest in non-small-cell lung cancer (NSCLC) cell lines in a dose-dependent manner, while showing lower toxicity against normal human lung epidermal cells. Peperomin E inhibited tumor growth in A549 xenograft BALB/c nude mice without significant secondary adverse effects, indicating that it may be safely used to treat NSCLC. Furthermore, the mechanisms underlying the anticancer effects of peperomin E have been investigated. Using an in silico target fishing method, we observed that peperomin E directly interacts with the active domain of DNA methyltransferase 1 (DNMT1), potentially affecting its genome methylation activity. Subsequent experiments verified that peperomin E decreased DNMT1 activity and expression, thereby decreasing global methylation and reactivating the epigenetically silenced tumor suppressor genes including RASSF1A, APC, RUNX3, and p16INK4, which in turn activates their mediated pro-apoptotic and cell cycle regulatory signaling pathways in lung cancer cells. The observations herein report for the first time that peperomin E is a potential chemotherapeutic agent for NSCLC. The anticancer effects of peperomin E may be partly attributable to its ability to demethylate and reactivate methylation-silenced tumor suppressor genes through direct inhibition of the activity and expression of DNMT1.

  9. Tumor Suppressor WWOX inhibits osteosarcoma metastasis by modulating RUNX2 function.

    PubMed

    Del Mare, Sara; Aqeilan, Rami I

    2015-08-10

    Osteosarcoma (OS) is among the most frequently occurring primary bone tumors, primarily affecting adolescents and young adults. This malignant osteoid forming tumor is characterized by its metastatic potential, mainly to lungs. We recently demonstrated that WW domain-containing oxidoreductase (WWOX) is frequently inactivated in human OS and that WWOX restoration in WWOX-negative OS cells suppresses tumorigenicity. Of note, WWOX levels are reduced in paired OS samples of post-treatment metastastectomies as compared to pre-treatment biopsies suggesting that decreased WWOX levels are associated with a more aggressive phenotype at the metastatic site. Nevertheless, little is known about WWOX function in OS metastasis. Here, we investigated the role of tumor suppressor WWOX in suppressing pulmonary OS metastasis both in vitro and in vivo. We demonstrated that ectopic expression of WWOX in OS cells, HOS and LM-7, inhibits OS invasion and cell migration in vitro. Furthermore, WWOX expression reduced tumor burden in vivo and inhibited metastases' seeding and colonization. Mechanistically, WWOX function is associated with reduced levels of RUNX2 metastatic target genes implicated in adhesion and motility. Our results suggest that WWOX plays a critical role in determining the aggressive phenotype of OS, and its expression could be an attractive therapeutic target to combat this devastating adolescent disease.

  10. Tumor Suppressor WWOX inhibits osteosarcoma metastasis by modulating RUNX2 function

    PubMed Central

    Del Mare, Sara; Aqeilan, Rami I.

    2015-01-01

    Osteosarcoma (OS) is among the most frequently occurring primary bone tumors, primarily affecting adolescents and young adults. This malignant osteoid forming tumor is characterized by its metastatic potential, mainly to lungs. We recently demonstrated that WW domain-containing oxidoreductase (WWOX) is frequently inactivated in human OS and that WWOX restoration in WWOX-negative OS cells suppresses tumorigenicity. Of note, WWOX levels are reduced in paired OS samples of post-treatment metastastectomies as compared to pre-treatment biopsies suggesting that decreased WWOX levels are associated with a more aggressive phenotype at the metastatic site. Nevertheless, little is known about WWOX function in OS metastasis. Here, we investigated the role of tumor suppressor WWOX in suppressing pulmonary OS metastasis both in vitro and in vivo. We demonstrated that ectopic expression of WWOX in OS cells, HOS and LM-7, inhibits OS invasion and cell migration in vitro. Furthermore, WWOX expression reduced tumor burden in vivo and inhibited metastases’ seeding and colonization. Mechanistically, WWOX function is associated with reduced levels of RUNX2 metastatic target genes implicated in adhesion and motility. Our results suggest that WWOX plays a critical role in determining the aggressive phenotype of OS, and its expression could be an attractive therapeutic target to combat this devastating adolescent disease. PMID:26256646

  11. Gld-1, a Tumor Suppressor Gene Required for Oocyte Development in Caenorhabditis Elegans

    PubMed Central

    Francis, R.; Barton, M. K.; Kimble, J.; Schedl, T.

    1995-01-01

    We have characterized 31 mutations in the gld-1 (defective in germline development) gene of Caenorhabditis elegans. In gld-1(null) hermaphrodites, oogenesis is abolished and a germline tumor forms where oocyte development would normally occur. By contrast, gld-1(null) males are unaffected. The hermaphrodite germline tumor appears to derive from germ cells that enter the meiotic pathway normally but then exit pachytene and return to the mitotic cycle. Certain gld-1 partial loss-of-function mutations also abolish oogenesis, but germ cells arrest in pachytene rather than returning to mitosis. Our results indicate that gld-1 is a tumor suppressor gene required for oocyte development. The tumorous phenotype suggests that gld-1(+) may function to negatively regulate proliferation during meiotic prophase and/or act to direct progression through meiotic prophase. We also show that gld-1(+) has an additional nonessential role in germline sex determination: promotion of hermaphrodite spermatogenesis. This function of gld-1 is inferred from a haplo-insufficient phenotype and from the properties of gain-of-function gld-1 mutations that cause alterations in the sexual identity of germ cells. PMID:7713419

  12. Tumor suppressor p53 negatively regulates glycolysis stimulated by hypoxia through its target RRAD.

    PubMed

    Zhang, Cen; Liu, Juan; Wu, Rui; Liang, Yingjian; Lin, Meihua; Liu, Jia; Chan, Chang S; Hu, Wenwei; Feng, Zhaohui

    2014-07-30

    Cancer cells display enhanced glycolysis to meet their energetic and biosynthetic demands even under normal oxygen concentrations. Recent studies have revealed that tumor suppressor p53 represses glycolysis under normoxia as a novel mechanism for tumor suppression. As a common microenvironmental stress for tumors, hypoxia drives the metabolic switch from the oxidative phosphorylation to glycolysis, which is crucial for survival and proliferation of cancer cells under hypoxia. The p53's role and mechanism in regulating glycolysis under hypoxia is poorly understood. Here, we found that p53 represses hypoxia-stimulated glycolysis in cancer cells through RRAD, a newly-identified p53 target. RRAD expression is frequently decreased in lung cancer. Ectopic expression of RRAD greatly reduces glycolysis whereas knockdown of RRAD promotes glycolysis in lung cancer cells. Furthermore, RRAD represses glycolysis mainly through inhibition of GLUT1 translocation to the plasma membrane. Under hypoxic conditions, p53 induces RRAD, which in turn inhibits the translocation of GLUT1 and represses glycolysis in lung cancer cells. Blocking RRAD by siRNA greatly abolishes p53's function in repressing glycolysis under hypoxia. Taken together, our results revealed an important role and mechanism of p53 in antagonizing the stimulating effect of hypoxia on glycolysis, which contributes to p53's function in tumor suppression.

  13. microRNA-622 acts as a tumor suppressor in hepatocellular carcinoma

    PubMed Central

    Song, Wei-Hua; Feng, Xiao-Jun; Gong, Shao-Juan; Chen, Jian-Ming; Wang, Shou-Mei; Xing, Dong-Juan; Zhu, Ming-Hua; Zhang, Shu-Hui; Xu, Ai-Min

    2015-01-01

    microRNAs (miRNAs) are important regulators of tumor development and progression. In this study, we aimed to explore the expression and role of miR-622 in hepatocellular carcinoma (HCC). We found that miR-622 was significantly downregulated in human HCC specimens compared to adjacent noncancerous liver tissues. miR-622 downregulation was significantly associated with aggressive parameters and poor prognosis in HCC. Enforced expression of miR-622 significantly decreased the proliferation and colony formation and induced apoptosis of HCC cells. In vivo studies demonstrated that miR-622 overexpression retarded the growth of HCC xenograft tumors. Bioinformatic analysis and luciferase reporter assays revealed that miR-622 directly targeted the 3′-untranslated region (UTR) of mitogen-activated protein 4 kinase 4 (MAP4K4) mRNA. Ectopic expression of miR-622 led to a significant reduction of MAP4K4 expression in HCC cells and xenograft tumors. Overexpression of MAP4K4 partially restored cell proliferation and colony formation and reversed the induction of apoptosis in miR-622-overexpressing HCC cells. Inhibition of JNK and NF-κB signaling phenocopied the anticancer effects of miR-622 on HCC cells. Taken together, miR-622 acts as a tumor suppressor in HCC and restoration of miR-622 may provide therapeutic benefits in the treatment of HCC. PMID:26467022

  14. How the other half lives, the amino-terminal domain of the retinoblastoma tumor suppressor protein.

    PubMed

    Goodrich, David W

    2003-11-01

    The retinoblastoma tumor suppressor gene (RB1) is currently the only known gene whose mutation is necessary and sufficient for the development of a human cancer. Mutation or deregulation of RB1 is observed so frequently in other tumor types that compromising RB1 function may be a prerequisite for malignant transformation. Identifying the molecular mechanisms that provide the basis for RB1-mediated tumor suppression has become an important goal in the quest to understand and treat cancer. The lion's share of research on these mechanisms has focused on the carboxy-terminal half of the RB1 encoded protein (pRB). This focus is with good reason since this part of the protein, now called the "large pocket," is required for most of its known activities identified in vitro and in vivo. Large pocket mediated mechanisms alone, however, cannot account for all observed properties of pRB. The thesis presented here is that the relatively uncharacterized amino-terminal half of the protein makes important contributions to pRB-mediated tumor suppression. The goals of this review are to summarize evidence indicating that an amino-terminal structural domain is important for pRB function and to suggest a general hypothesis as to how this domain can be integrated with current models of pRB function.

  15. gld-1, a tumor suppressor gene required for oocyte development in Caenorhabditis elegans

    SciTech Connect

    Francis, R.; Schedl, T.; Barton, M.K.; Kimble, J.

    1995-02-01

    We have characterized 31 mutations in the gld-1 (defective in germline development) gene of Caenorhabditis elegans. In gld-1 (null) hermaphrodites, oogenesis is abolished and a germline tumor forms where oocyte development would normally occur. By contrast, gld-1 (null) males are unaffected. The hermaphrodite germline tumor appears to derive from germ cells that enter the meiotic pathway normally but then exit pachytene and return to the mitotic cycle. Certain gld-1 partial loss-of-function mutations also abolish oogenesis, but germ cells arrest in pachytene rather than returning to mitosis. Our results indicate that gld-1 is a tumor suppressor gene required for oocyte development. The tumorous phenotype suggests that gld-1(+) may function to negatively regulate proliferation during meiotic prophase and/or act to direct progression through meiotic prophase. We also show that gld-1(+) has an additional nonessential role in germline sex determination: promotion of hermaphrodite spermatogenesis. This function of gld-1 is inferred from a haplo-insufficient phenotype and from the properties of gain-of-function gld-1 mutations that cause alterations in the sexual identity of germ cells. 69 refs., 10 figs., 8 tabs.

  16. Tumor-suppressor genes that escape from X-inactivation contribute to cancer sex bias.

    PubMed

    Dunford, Andrew; Weinstock, David M; Savova, Virginia; Schumacher, Steven E; Cleary, John P; Yoda, Akinori; Sullivan, Timothy J; Hess, Julian M; Gimelbrant, Alexander A; Beroukhim, Rameen; Lawrence, Michael S; Getz, Gad; Lane, Andrew A

    2017-01-01

    There is a striking and unexplained male predominance across many cancer types. A subset of X-chromosome genes can escape X-inactivation, which would protect females from complete functional loss by a single mutation. To identify putative 'escape from X-inactivation tumor-suppressor' (EXITS) genes, we examined somatic alterations from >4,100 cancers across 21 tumor types for sex bias. Six of 783 non-pseudoautosomal region (PAR) X-chromosome genes (ATRX, CNKSR2, DDX3X, KDM5C, KDM6A, and MAGEC3) harbored loss-of-function mutations more frequently in males (based on a false discovery rate < 0.1), in comparison to zero of 18,055 autosomal and PAR genes (Fisher's exact P < 0.0001). Male-biased mutations in genes that escape X-inactivation were observed in combined analysis across many cancers and in several individual tumor types, suggesting a generalized phenomenon. We conclude that biallelic expression of EXITS genes in females explains a portion of the reduced cancer incidence in females as compared to males across a variety of tumor types.

  17. Tumor suppressor BRCA1 epigenetically controls oncogenic microRNA-155

    PubMed Central

    Chang, Suhwan; Wang, Rui-Hong; Akagi, Keiko; Kim, Kyung-Ae; Martin, Betty K; Cavallone, Luca; Haines, Diana C; Basik, Mark; Mai, Phuong; Poggi, Elizabeth; Isaacs, Claudine; Looi, Lai M; Mun, Kein S; Greene, Mark H; Byers, Stephen W; Teo, Soo H; Deng, Chu-Xia; Sharan, Shyam K

    2012-01-01

    BRCA1, a well-known tumor suppressor with multiple interacting partners, is predicted to have diverse biological functions. However, so far its only well-established role is in the repair of damaged DNA and cell cycle regulation. In this regard, the etiopathological study of low-penetrant variants of BRCA1 provides an opportunity to uncover its other physiologically important functions. Using this rationale, we studied the R1699Q variant of BRCA1, a potentially moderate-risk variant, and found that it does not impair DNA damage repair but abrogates the repression of microRNA-155 (miR-155), a bona fide oncomir. Mechanistically, we found that BRCA1 epigenetically represses miR-155 expression via its association with HDAC2, which deacetylates histones H2A and H3 on the miR-155 promoter. We show that overexpression of miR-155 accelerates whereas the knockdown of miR-155 attenuates the growth of tumor cell lines in vivo. Our findings demonstrate a new mode of tumor suppression by BRCA1 and suggest that miR-155 is a potential therapeutic target for BRCA1-deficient tumors. PMID:21946536

  18. BRAF-activated LncRNA functions as a tumor suppressor in papillary thyroid cancer

    PubMed Central

    Guo, Kai; Ma, Ben; Cao, Yi-Ming; Xiang, Jun; Lu, Zhong-Wu; Zhu, Yong-Xue; Li, Duan-Shu; Ji, Qing-Hai

    2017-01-01

    Long non-coding RNAs (lncRNAs) participate in cancer cell tumorigenesis, cell cycle control, migration, proliferation, apoptosis, metastasis and drug resistance. The BRAF-activated non-coding RNA (BANCR) functions as both an oncogene and a tumor suppressor. Here, we investigated BANCR's role in papillary thyroid carcinoma (PTC) by assessing BANCR levels in PTC and matched normal thyroid epithelial tissues from 92 patients using qRT-PCR. We also used lentiviral vectors to establish PTC cell lines to investigate the effects of BANCR overexpression on cancer cell proliferation, apoptosis, migration and invasion. Our results indicate BANCR levels are lower in PTC tumor tissues than control tissues. Decreased BANCR levels correlate with tumor size, the presence of multifocal lesions and advanced PTC stage. BANCR overexpression reduced PTC cell proliferation and promoted apoptosis, which inhibited metastasis. It also inactivated ERK1/2 and p38, and this effect was enhanced by treatment with the MEK inhibitor U0126. Finally, BANCR overexpression dramatically inhibited tumor growth from PTC cells in xenograft mouse models. These results suggest BANCR inhibits tumorigenesis in PTC and that BANCR levels may be used as a novel prognostic marker. PMID:27462868

  19. Lowered Expression of Tumor Suppressor Candidate MYO1C Stimulates Cell Proliferation, Suppresses Cell Adhesion and Activates AKT

    PubMed Central

    Visuttijai, Kittichate; Pettersson, Jennifer; Mehrbani Azar, Yashar; van den Bout, Iman; Örndal, Charlotte; Marcickiewicz, Janusz; Nilsson, Staffan; Hörnquist, Michael; Olsson, Björn; Ejeskär, Katarina

    2016-01-01

    Myosin-1C (MYO1C) is a tumor suppressor candidate located in a region of recurrent losses distal to TP53. Myo1c can tightly and specifically bind to PIP2, the substrate of Phosphoinositide 3-kinase (PI3K), and to Rictor, suggesting a role for MYO1C in the PI3K pathway. This study was designed to examine MYO1C expression status in a panel of well-stratified endometrial carcinomas as well as to assess the biological significance of MYO1C as a tumor suppressor in vitro. We found a significant correlation between the tumor stage and lowered expression of MYO1C in endometrial carcinoma samples. In cell transfection experiments, we found a negative correlation between MYO1C expression and cell proliferation, and MYO1C silencing resulted in diminished cell migration and adhesion. Cells expressing excess of MYO1C had low basal level of phosphorylated protein kinase B (PKB, a.k.a. AKT) and cells with knocked down MYO1C expression showed a quicker phosphorylated AKT (pAKT) response in reaction to serum stimulation. Taken together the present study gives further evidence for tumor suppressor activity of MYO1C and suggests MYO1C mediates its tumor suppressor function through inhibition of PI3K pathway and its involvement in loss of contact inhibition. PMID:27716847

  20. Tumor Suppressor Function of the SEMA3B Gene in Human Lung and Renal Cancers

    PubMed Central

    Senchenko, Vera N.; Pronina, Irina V.; Khodyrev, Dmitry S.; Kudryavtseva, Anna V.; Krasnov, George S.; Gerashchenko, Ganna V.; Chashchina, Larisa I.; Kazubskaya, Tatiana P.; Kondratieva, Tatiana T.; Lerman, Michael I.; Angeloni, Debora; Braga, Eleonora A.; Kashuba, Vladimir I.

    2015-01-01

    The SEMA3B gene is located in the 3p21.3 LUCA region, which is frequently affected in different types of cancer. The objective of our study was to expand our knowledge of the SEMA3B gene as a tumor suppressor and the mechanisms of its inactivation. In this study, several experimental approaches were used: tumor growth analyses and apoptosis assays in vitro and in SCID mice, expression and methylation assays and other. With the use of the small cell lung cancer cell line U2020 we confirmed the function of SEMA3B as a tumor suppressor, and showed that the suppression can be realized through the induction of apoptosis and, possibly, associated with the inhibition of angiogenesis. In addition, for the first time, high methylation frequencies have been observed in both intronic (32-39%) and promoter (44-52%) CpG-islands in 38 non-small cell lung carcinomas, including 16 squamous cell carcinomas (SCC) and 22 adenocarcinomas (ADC), and in 83 clear cell renal cell carcinomas (ccRCC). Correlations between the methylation frequencies of the promoter and the intronic CpG-islands of SEMA3B with tumor stage and grade have been revealed for SCC, ADC and ccRCC. The association between the decrease of the SEMA3B mRNA level and hypermethylation of the promoter and the intronic CpG-islands has been estimated in renal primary tumors (P < 0.01). Using qPCR, we observed on the average 10- and 14-fold decrease of the SEMA3B mRNA level in SCC and ADC, respectively, and a 4-fold decrease in ccRCC. The frequency of this effect was high in both lung (92-95%) and renal (84%) tumor samples. Moreover, we showed a clear difference (P < 0.05) of the SEMA3B relative mRNA levels in ADC with and without lymph node metastases. We conclude that aberrant expression and methylation of SEMA3B could be suggested as markers of lung and renal cancer progression. PMID:25961819

  1. Identification of a third protein 4.1 tumor suppressor, protein 4.1R, in meningioma pathogenesis

    SciTech Connect

    Robb, Victoria A.; Li, Wen; Gascard, Philippe; Perry, Arie; Mohandas, Narla; Gutmann, David H.

    2003-06-11

    Meningiomas are common tumors of the central nervous system, however, the mechanisms under lying their pathogenesis are largely undefined. Two members of the Protein 4.1 super family, the neuro fibromatosis 2 (NF2) gene product (merlin/schwannomin) and Protein 4.1B have been implicated as meningioma tumor suppressors. In this report, we demonstrate that another Protein 4.1 family member, Protein 4.1R, also functions as a meningioma tumor suppressor. Based on the assignment of the Protein 4.1R gene to chromosome 1p32-36, a common region of deletion observed in meningiomas, we analyzed Protein 4.1R expression in meningioma cell lines and surgical tumor specimens. We observed loss of Protein 4.1R protein expression in two meningioma cell lines (IOMM-Lee, CH157-MN) by Western blotting as well as in 6 of 15 sporadic meningioma as by immuno histo chemistry (IHC). Analysis of a subset of these sporadic meningiomas by fluorescent in situ hybridization (FISH) with a Protein 4.1R specific probe demonstrated 100 percent concordance with the IHC results. In support of a meningioma tumor suppressor function, over expression of Protein 4.1R resulted in suppression of IOMM-Lee and CH157MN cell proliferation. Similar to the Protein 4.1B and merlin meningioma tumor suppressors, Protein 4.1R localization in the membrane fraction increased significantly under conditions of growth arrest in vitro. Lastly, Protein 4.1R interacted with some known merlin/Protein 4.1B interactors such as CD44 and bII-spectrin, but did not associate with the Protein 4.1B interactors 14-3-3 and PRMT3 or the merlin binding proteins SCHIP-1 and HRS. Collectively, these results suggest that Protein 4.1R functions as an important tumor suppressor important in the molecular pathogenesis of meningioma.

  2. [Correlation of size of the primary tumor and axillary node status with the p53 tumor suppressor gene in carcinoma of the breast].

    PubMed

    Topić, Brano; Stanković, N; Savjak, D; Grbić, S

    2002-01-01

    Correlation of standard pathomorphological prognostic parameters, primary tumor size and axillary nodal status with new prognostic factor in breast carcinoma: tumor suppressor gene p53 was analyzed. The studied sample included 65 women who underwent surgery for breast carcinoma at the Surgical Clinic of Clinical Center Banja Luka, from January 1st 1997 till January 1st 1999. Statistical data analysis was performed and correlation of prognostic factors was determined. The majority of authors in this field agree that the primary tumor size and axillary nodal status are the two most important prognostic factors. These factors are the best predictors of prognosis and survival of women who had the tumor and were operated on. Tumor markers were immunohistochemically determined in the last ten years and, according to the majority of authors, are still considered the additional or relative prognostic factors in breast carcinoma. Their prognostic value and significance increase almost daily. Most frequently determined tumor markers are bcl-2, pS2, Ki-67 and p53. There was a positive, directly proportional relationship between primary tumor size and tumor suppressor gene p53, but there was no positive correlation between the axillary nodal status and tumor suppressor gene p53. Significance of determination of new tumor markers as the prognostic factors was emphasized. These markers represent a powerful tool in the early detection and prevention of breast carcinoma.

  3. ME-10TUMOR MICROENVIRONMENT INFILTRATING MYELOID DERIVED SUPPRESSOR CELLS INHIBIT ANTI-TUMOR T CELL RESPONSES

    PubMed Central

    Kamran, Neha; Ayala, Mariela; Li, Youping; Assi, Hikmat; Candolfi, Marianela; Dzaman, Marta; Lowenstein, Pedro; Castro, Maria

    2014-01-01

    MDSCs represent a population of immature myeloid cells at various stages of differentiation that inhibit anti-tumor T cell-mediated responses. We demonstrate the accumulation of MDSCs in GL26 induced glioma and B16 melanoma bearing mice. Absolute numbers of Ly-6G+ (Gr-1high) MDSCs showed a 200 fold increase within the tumor microenvironment (TME) 28 days post-tumor implantation. The numbers of Ly-6C+ (Gr-1low) MDSCs also showed a similar trend within the TME. While this massive influx of MDSCs was noted within intracranial tumors, MDSC levels did not increase in the dLNs, spleen or bone marrow (BM) of intracranial tumor bearing mice. MDSCs numbers were significantly elevated in the blood of GL26 intracranial tumor bearing mice at 28 days. Mice bearing B16 tumors in the flank showed a ∼5 fold increased influx of Ly-6G+ MDSCs while the Ly6C+ MDSCs increased marginally by 1.1 fold within the tumor mass. Levels of circulating MDSCs also increased by ∼10 fold, while the levels of splenic MDSCs did not change. While both Ly-6G+ and Ly6C+ MDSCs isolated from the brain TME of GL26 intracranial tumor bearing mice inhibited antigen-specific T cell proliferation, Ly6C+ MDSC were found to be more efficient. Ly6G+ or Ly6C+ MDSCs from the bone marrow of intracranial tumor bearing mice failed to suppress antigen-specific T cell proliferation. Splenic and bone marrow MDSCs from naïve mice also did not inhibit antigen-specific T cell proliferation suggesting that TME derived factors may activate MDSCs to exert their immune-suppressive properties. Microarray analysis of glioma cell lines showed elevated levels of CXCL1 mRNA and splenic MDSCs from GL26 tumor mice showed upregulation of the CXCR2 mRNA. Preliminary experiments indicate that CXCR2 signaling mediates MDSC chemotaxis. Overall, our data suggests that strategies that inhibit MDSC recruitment to the TME and/or block their activity could enhance the T cell mediated tumor clearance.

  4. CFTR is a tumor suppressor gene in murine and human intestinal cancer

    PubMed Central

    Than, BLN; Linnekamp, JF; Starr, TK; Largaespada, DA; Rod, A; Zhang, Y; Bruner, V; Abrahante, J; Schumann, A; Luczak, T; Niemczyk, A; O’Sullivan, MG; Medema, JP; Fijneman, RJA; Meijer, GA; Van den Broek, E; Hodges, CA; Scott, PM; Vermeulen, L; Cormier, RT

    2016-01-01

    CFTR, the cystic fibrosis (CF) gene, encodes for the CFTR protein that plays an essential role in anion regulation and tissue homeostasis of various epithelia. In the gastrointestinal (GI) tract CFTR promotes chloride and bicarbonate secretion, playing an essential role in ion and acid–base homeostasis. Cftr has been identified as a candidate driver gene for colorectal cancer (CRC) in several Sleeping Beauty DNA transposon-based forward genetic screens in mice. Further, recent epidemiological and clinical studies indicate that CF patients are at high risk for developing tumors in the colon. To investigate the effects of CFTR dysregulation on GI cancer, we generated ApcMin mice that carried an intestinal-specific knockout of Cftr. Our results indicate that Cftr is a tumor suppressor gene in the intestinal tract as Cftr mutant mice developed significantly more tumors in the colon and the entire small intestine. In Apc+/+ mice aged to ~ 1 year, Cftr deficiency alone caused the development of intestinal tumors in >60% of mice. Colon organoid formation was significantly increased in organoids created from Cftr mutant mice compared with wild-type controls, suggesting a potential role of Cftr in regulating the intestinal stem cell compartment. Microarray data from the Cftr-deficient colon and the small intestine identified dysregulated genes that belong to groups of immune response, ion channel, intestinal stem cell and other growth signaling regulators. These associated clusters of genes were confirmed by pathway analysis using Ingenuity Pathway Analysis and gene set enrichment analysis (GSEA). We also conducted RNA Seq analysis of tumors from Apc+/+ Cftr knockout mice and identified sets of genes dysregulated in tumors including altered Wnt β-catenin target genes. Finally we analyzed expression of CFTR in early stage human CRC patients stratified by risk of recurrence and found that loss of expression of CFTR was significantly associated with poor disease

  5. CFTR is a tumor suppressor gene in murine and human intestinal cancer.

    PubMed

    Than, B L N; Linnekamp, J F; Starr, T K; Largaespada, D A; Rod, A; Zhang, Y; Bruner, V; Abrahante, J; Schumann, A; Luczak, T; Niemczyk, A; O'Sullivan, M G; Medema, J P; Fijneman, R J A; Meijer, G A; Van den Broek, E; Hodges, C A; Scott, P M; Vermeulen, L; Cormier, R T

    2016-08-11

    CFTR, the cystic fibrosis (CF) gene, encodes for the CFTR protein that plays an essential role in anion regulation and tissue homeostasis of various epithelia. In the gastrointestinal (GI) tract CFTR promotes chloride and bicarbonate secretion, playing an essential role in ion and acid-base homeostasis. Cftr has been identified as a candidate driver gene for colorectal cancer (CRC) in several Sleeping Beauty DNA transposon-based forward genetic screens in mice. Further, recent epidemiological and clinical studies indicate that CF patients are at high risk for developing tumors in the colon. To investigate the effects of CFTR dysregulation on GI cancer, we generated Apc(Min) mice that carried an intestinal-specific knockout of Cftr. Our results indicate that Cftr is a tumor suppressor gene in the intestinal tract as Cftr mutant mice developed significantly more tumors in the colon and the entire small intestine. In Apc(+/+) mice aged to ~1 year, Cftr deficiency alone caused the development of intestinal tumors in >60% of mice. Colon organoid formation was significantly increased in organoids created from Cftr mutant mice compared with wild-type controls, suggesting a potential role of Cftr in regulating the intestinal stem cell compartment. Microarray data from the Cftr-deficient colon and the small intestine identified dysregulated genes that belong to groups of immune response, ion channel, intestinal stem cell and other growth signaling regulators. These associated clusters of genes were confirmed by pathway analysis using Ingenuity Pathway Analysis and gene set enrichment analysis (GSEA). We also conducted RNA Seq analysis of tumors from Apc(+/+) Cftr knockout mice and identified sets of genes dysregulated in tumors including altered Wnt β-catenin target genes. Finally we analyzed expression of CFTR in early stage human CRC patients stratified by risk of recurrence and found that loss of expression of CFTR was significantly associated with poor disease

  6. Non genomic loss of function of tumor suppressors in CML: BCR-ABL promotes IκBα mediated p53 nuclear exclusion

    PubMed Central

    Crivellaro, Sabrina; Panuzzo, Cristina; Carrà, Giovanna; Volpengo, Alessandro; Crasto, Francesca; Gottardi, Enrico; Familiari, Ubaldo; Papotti, Mauro; Torti, Davide; Piazza, Rocco; Redaelli, Sara; Taulli, Riccardo; Guerrasio, Angelo; Saglio, Giuseppe; Morotti, Alessandro

    2015-01-01

    Tumor suppressor function can be modulated by subtle variation of expression levels, proper cellular compartmentalization and post-translational modifications, such as phosphorylation, acetylation and sumoylation. The non-genomic loss of function of tumor suppressors offers a challenging therapeutic opportunity. The reactivation of a tumor suppressor could indeed promote selective apoptosis of cancer cells without affecting normal cells. The identification of mechanisms that affect tumor suppressor functions is therefore essential. In this work, we show that BCR-ABL promotes the accumulation of the NFKBIA gene product, IκBα, in the cytosol through physical interaction and stabilization of the protein. Furthermore, BCR-ABL/IκBα complex acts as a scaffold protein favoring p53 nuclear exclusion. We therefore identify a novel BCR-ABL/IκBα/p53 network, whereby BCR-ABL functionally inactivates a key tumor suppressor. PMID:26295305

  7. Selective Retention of an Inactive Allele of the DKK2 Tumor Suppressor Gene in Hepatocellular Carcinoma

    PubMed Central

    Lin, Yung-Feng; Li, Ling-Hui; Lin, Chih-Hung; Tsou, Mei-Hua; Chuang, Ming-Tai Kiffer; Wu, Keh-Ming; Liao, Tsai-Lien; Li, Jian-Chiuan; Wang, Wei-Jie; Tomita, Angela; Tomita, Beverly; Huang, Shiu-Feng; Tsai, Shih-Feng

    2016-01-01

    In an effort to identify the functional alleles associated with hepatocellular carcinoma (HCC), we investigated 152 genes found in the 4q21-25 region that exhibited loss of heterozygosity (LOH). A total of 2,293 pairs of primers were designed for 1,449 exonic and upstream promoter regions to amplify and sequence 76.8–114 Mb on human chromosome 4. Based on the results from analyzing 12 HCC patients and 12 healthy human controls, we discovered 1,574 sequence variations. Among the 99 variants associated with HCC (p < 0.05), four are from the Dickkopf 2 (DKK2) gene: three in the promoter region (g.-967A>T, g.-923C>A, and g.-441T>G) and one in the 5’UTR (c.550T>C). To verify the results, we expanded the subject cohort to 47 HCC cases and 88 healthy controls for conducting haplotype analysis. Eight haplotypes were detected in the non-tumor liver tissue samples, but one major haplotype (TAGC) was found in the tumor tissue samples. Using a reporter assay, this HCC-associated allele registered the lowest level of promoter activity among all the tested haplotype sequences. Retention of this allele in LOH was associated with reduced DKK2 transcription in the HCC tumor tissues. In HuH-7 cells, DKK2 functioned in the Wnt/β-catenin signaling pathway, as an antagonist of Wnt3a, in a dose-dependent manner that inhibited Wnt3a-induced cell proliferation. Taken together, the genotyping and functional findings are consistent with the hypothesis that DKK2 is a tumor suppressor; by selectively retaining a transcriptionally inactive DKK2 allele, the reduction of DKK2 function results in unchecked Wnt/β-catenin signaling, contributing to HCC oncogenesis. Thus our study reveals a new mechanism through which a tumor suppressor gene in a LOH region loses its function by allelic selection. PMID:27203079

  8. Conditional inactivation of the mouse Wwox tumor suppressor gene recapitulates the null phenotype†

    PubMed Central

    Abdeen, Suhaib K.; Mare, Sara Del; Hussain, Sadeeq; Remaileh, Muhannad Abu; Salah, Zaidoun; Hagan, John; Rawahneh, Maysoon; Pu, Xin-an; Russell, Stacey; Stein, Janet L.; Stein, Gary S.; Lian, Jane B.; Aqeilan, Rami I.

    2013-01-01

    WW domain-containing oxidoreductase (WWOX) is highly conserved in both humans and murine. WWOX spans the second most common human chromosomal fragile site, FRA16D, and is commonly inactivated in multiple human cancers. Modeling WWOX inactivation in mice revealed a complex phenotype including postnatal lethality, defects in bone metabolism and steroidogenesis and tumor suppressor function resulting in osteosarcomas. For better understanding of WWOX roles in different tissues at distinct stages of development and in pathological conditions, Wwox conditional knockout mice were generated in which loxp sites flank exon 1 in the Wwox allele. We demonstrated that Cre-mediated recombination using EIIA-Cre, a Cre line expressed in germline, results in postnatal lethality by age of three weeks and decreased bone mineralization resembling total ablation of WWOX as in conventional null mice. This animal model will be useful to study distinct roles of WWOX in multiple tissues at different ages. PMID:23254685

  9. Pleiotropic Functions of Tumor Suppressor WWOX in Normal and Cancer Cells.

    PubMed

    Abu-Remaileh, Muhannad; Joy-Dodson, Emma; Schueler-Furman, Ora; Aqeilan, Rami I

    2015-12-25

    WW domain-containing oxidoreductase (WWOX), originally marked as a likely tumor suppressor gene, has over the years become recognized for its role in a much wider range of cellular activities. Phenotypic effects displayed in animal studies, along with resolution of WWOX's architecture, fold, and binding partners, point to the protein's multifaceted biological functions. Results from a series of complementary experiments seem to indicate WWOX's involvement in metabolic regulation. More recently, clinical studies involving cases of severe encephalopathy suggest that WWOX also plays a part in controlling CNS development, further expanding our understanding of the breadth and complexity of WWOX behavior. Here we present a short overview of the various approaches taken to study this dynamic gene, emphasizing the most recent findings regarding WWOX's metabolic- and CNS-associated functions and their underlying molecular basis.

  10. The tumor suppressor WW domain-containing oxidoreductase modulates cell metabolism

    PubMed Central

    Abu-Remaileh, Muhannad

    2015-01-01

    The WW domain-containing oxidoreductase (WWOX) encodes a tumor suppressor that is frequently altered in cancer. WWOX binds several proteins and thus is postulated to be involved in a variety of cellular processes. Interestingly, Wwox-knockout mice develop normally in utero but succumb to hypoglycemia and other metabolic defects early in life resulting in their death by 3–4 weeks of age. Cumulative evidence has linked WWOX with cellular metabolism including steroid metabolism, high-density lipoprotein cholesterol (HDL-C) metabolism, bone metabolism and, more recently, glucose metabolism. In this review, we discuss these evolving functions for WWOX and how its deletion affects cellular metabolism and neoplastic progression. PMID:25491415

  11. Tumor suppressor WWOX binds to ΔNp63α and sensitizes cancer cells to chemotherapy.

    PubMed

    Salah, Z; Bar-mag, T; Kohn, Y; Pichiorri, F; Palumbo, T; Melino, G; Aqeilan, R I

    2013-01-31

    The WWOX tumor suppressor is a WW domain-containing protein. Its function in the cell has been shown to be mediated, in part, by interacting with its partners through its first WW (WW1) domain. Here, we demonstrated that WWOX via WW1 domain interacts with p53 homolog, ΔNp63α. This protein-protein interaction stabilizes ΔNp63α, through antagonizing function of the E3 ubiquitin ligase ITCH, inhibits nuclear translocation of ΔNp63α into the nucleus and suppresses ΔNp63α transactivation function. Additionally, we found that this functional crosstalk reverses cancer cells resistance to cisplatin, mediated by ΔNp63α, and consequently renders these cells more sensitive to undergo apoptosis. These findings suggest a functional crosstalk between WWOX and ΔNp63α in tumorigenesis.

  12. Tumor suppressor WWOX binds to ΔNp63α and sensitizes cancer cells to chemotherapy

    PubMed Central

    Salah, Z; Bar-mag, T; Kohn, Y; Pichiorri, F; Palumbo, T; Melino, G; Aqeilan, R I

    2013-01-01

    The WWOX tumor suppressor is a WW domain-containing protein. Its function in the cell has been shown to be mediated, in part, by interacting with its partners through its first WW (WW1) domain. Here, we demonstrated that WWOX via WW1 domain interacts with p53 homolog, ΔNp63α. This protein–protein interaction stabilizes ΔNp63α, through antagonizing function of the E3 ubiquitin ligase ITCH, inhibits nuclear translocation of ΔNp63α into the nucleus and suppresses ΔNp63α transactivation function. Additionally, we found that this functional crosstalk reverses cancer cells resistance to cisplatin, mediated by ΔNp63α, and consequently renders these cells more sensitive to undergo apoptosis. These findings suggest a functional crosstalk between WWOX and ΔNp63α in tumorigenesis. PMID:23370280

  13. Conditional inactivation of the mouse Wwox tumor suppressor gene recapitulates the null phenotype.

    PubMed

    Abdeen, Suhaib K; Del Mare, Sara; Hussain, Sadeeq; Abu-Remaileh, Muhannad; Salah, Zaidoun; Hagan, John; Rawahneh, Maysoon; Pu, Xin-An; Russell, Stacey; Stein, Janet L; Stein, Gary S; Lian, Jane B; Aqeilan, Rami I

    2013-07-01

    WW domain-containing oxidoreductase (WWOX) is highly conserved in both human and murine. WWOX spans the second most common human chromosomal fragile site, FRA16D, and is commonly inactivated in multiple human cancers. Modeling WWOX inactivation in mice revealed a complex phenotype including postnatal lethality, defects in bone metabolism and steroidogenesis and tumor suppressor function resulting in osteosarcomas. For better understanding of WWOX roles in different tissues at distinct stages of development and in pathological conditions, Wwox conditional knockout mice were generated in which loxp sites flank exon 1 in the Wwox allele. We demonstrated that Cre-mediated recombination using EIIA-Cre, a Cre line expressed in germline, results in postnatal lethality by age of 3 weeks and decreased bone mineralization resembling total ablation of WWOX as in conventional null mice. This animal model will be useful to study distinct roles of WWOX in multiple tissues at different ages.

  14. Discovery of novel tumor suppressor p53 response elements using information theory

    PubMed Central

    Lyakhov, Ilya G.; Krishnamachari, Annangarachari; Schneider, Thomas D.

    2008-01-01

    An accurate method for locating genes under tumor suppressor p53 control that is based on a well-established mathematical theory and built using naturally occurring, experimentally proven p53 sites is essential in understanding the complete p53 network. We used a molecular information theory approach to create a flexible model for p53 binding. By searching around transcription start sites in human chromosomes 1 and 2, we predicted 16 novel p53 binding sites and experimentally demonstrated that 15 of the 16 (94%) sites were bound by p53. Some were also bound by the related proteins p63 and p73. Thirteen of the adjacent genes were controlled by at least one of the proteins. Eleven of the 16 sites (69%) had not been identified previously. This molecular information theory approach can be extended to any genetic system to predict new sites for DNA-binding proteins. PMID:18495754

  15. Expression of the human tumor suppressor p53 induces cell death in Pichia pastoris.

    PubMed

    Abdelmoula-Souissi, Salma; Mabrouk, Imed; Gargouri, Ali; Mokdad-Gargouri, Raja

    2012-02-01

    The human tumor suppressor p53 is known as guardian of genome because of its involvement in many signals related to cell life or death. In this work, we report that human p53 induces cell death in the yeast Pichia pastoris. We showed a growth inhibition effect, which increased with the p53 protein expression level in recombinant Mut(s) (methanol utilization slow) strain of Pichia. However, no effect of p53 was observed in recombinant strain of Mut(+) (methanol utilization plus) phenotype. Interestingly, human p53 induces cell death in recombinant strains Mut(s) with characteristic markers of apoptosis such as DNA fragmentation, exposure of phosphatidylserine, and reactive oxygen species generation. Taken together, our results strongly suggest that human p53 is biologically active in this heterologous context. Thus, we propose that P. pastoris could be a useful tool to better understand the biological function of human p53.

  16. Regulation of Notch signaling and endocytosis by the Lgl neoplastic tumor suppressor

    PubMed Central

    Portela, Marta; Parsons, Linda M; Grzeschik, Nicola A; Richardson, Helena E

    2015-01-01

    The evolutionarily conserved neoplastic tumor suppressor protein, Lethal (2) giant larvae (Lgl), plays roles in cell polarity and tissue growth via regulation of the Hippo pathway. In our recent study, we showed that in the developing Drosophila eye epithelium, depletion of Lgl leads to increased ligand-dependent Notch signaling. lgl mutant tissue also exhibits an accumulation of early endosomes, recycling endosomes, early-multivesicular body markers and acidic vesicles. We showed that elevated Notch signaling in lgl− tissue can be rescued by feeding larvae the vesicle de-acidifying drug chloroquine, revealing that Lgl attenuates Notch signaling by limiting vesicle acidification. Strikingly, chloroquine also rescued the lgl− overgrowth phenotype, suggesting that the Hippo pathway defects were also rescued. In this extraview, we provide additional data on the regulation of Notch signaling and endocytosis by Lgl, and discuss possible mechanisms by which Lgl depletion contributes to signaling pathway defects and tumorigenesis. PMID:25789785

  17. Control of signaling-mediated clearance of apoptotic cells by the tumor suppressor p53

    PubMed Central

    Yoon, Kyoung Wan; Byun, Sanguine; Kwon, Eunjeong; Hwang, So-Young; Chu, Kiki; Hiraki, Masatsugu; Jo, Seung-Hee; Weins, Astrid; Hakroush, Samy; Cebulla, Angelika; Sykes, David B.; Greka, Anna; Mundel, Peter; Fisher, David E.; Mandinova, Anna; Lee, Sam W.

    2016-01-01

    The inefficient clearance of dying cells can lead to abnormal immune responses, such as unresolved inflammation and autoimmune conditions. We show that tumor suppressor p53 controls signaling-mediated phagocytosis of apoptotic cells through its target, Death Domain1α (DD1α), which suggests that p53 promotes both the proapoptotic pathway and postapoptotic events. DD1α appears to function as an engulfment ligand or receptor that engages in homophilic intermolecular interaction at intercellular junctions of apoptotic cells and macrophages, unlike other typical scavenger receptors that recognize phosphatidylserine on the surface of dead cells. DD1α-deficient mice showed in vivo defects in clearing dying cells, which led to multiple organ damage indicative of immune dysfunction. p53-induced expression of DD1α thus prevents persistence of cell corpses and ensures efficient generation of precise immune responses. PMID:26228159

  18. Retinoblastoma tumor suppressor functions shared by stem cell and cancer cell strategies

    PubMed Central

    Kohno, Susumu; Kitajima, Shunsuke; Sasaki, Nobunari; Takahashi, Chiaki

    2016-01-01

    Carcinogenic transformation of somatic cells resembles nuclear reprogramming toward the generation of pluripotent stem cells. These events share eternal escape from cellular senescence, continuous self-renewal in limited but certain population of cells, and refractoriness to terminal differentiation while maintaining the potential to differentiate into cells of one or multiple lineages. As represented by several oncogenes those appeared to be first keys to pluripotency, carcinogenesis and nuclear reprogramming seem to share a number of core mechanisms. The retinoblastoma tumor suppressor product retinoblastoma (RB) seems to be critically involved in both events in highly complicated manners. However, disentangling such complicated interactions has enabled us to better understand how stem cell strategies are shared by cancer cells. This review covers recent findings on RB functions related to stem cells and stem cell-like behaviors of cancer cells. PMID:27114748

  19. Pleiotropic Functions of Tumor Suppressor WWOX in Normal and Cancer Cells*

    PubMed Central

    Abu-Remaileh, Muhannad; Joy-Dodson, Emma; Schueler-Furman, Ora; Aqeilan, Rami I.

    2015-01-01

    WW domain-containing oxidoreductase (WWOX), originally marked as a likely tumor suppressor gene, has over the years become recognized for its role in a much wider range of cellular activities. Phenotypic effects displayed in animal studies, along with resolution of WWOX's architecture, fold, and binding partners, point to the protein's multifaceted biological functions. Results from a series of complementary experiments seem to indicate WWOX's involvement in metabolic regulation. More recently, clinical studies involving cases of severe encephalopathy suggest that WWOX also plays a part in controlling CNS development, further expanding our understanding of the breadth and complexity of WWOX behavior. Here we present a short overview of the various approaches taken to study this dynamic gene, emphasizing the most recent findings regarding WWOX's metabolic- and CNS-associated functions and their underlying molecular basis. PMID:26499798

  20. The tumor suppressor PTEN and the PDK1 kinase regulate formation of the columnar neural epithelium.

    PubMed

    Grego-Bessa, Joaquim; Bloomekatz, Joshua; Castel, Pau; Omelchenko, Tatiana; Baselga, José; Anderson, Kathryn V

    2016-01-26

    Epithelial morphogenesis and stability are essential for normal development and organ homeostasis. The mouse neural plate is a cuboidal epithelium that remodels into a columnar pseudostratified epithelium over the course of 24 hr. Here we show that the transition to a columnar epithelium fails in mutant embryos that lack the tumor suppressor PTEN, although proliferation, patterning and apical-basal polarity markers are normal in the mutants. The Pten phenotype is mimicked by constitutive activation of PI3 kinase and is rescued by the removal of PDK1 (PDPK1), but does not depend on the downstream kinases AKT and mTORC1. High resolution imaging shows that PTEN is required for stabilization of planar cell packing in the neural plate and for the formation of stable apical-basal microtubule arrays. The data suggest that appropriate levels of membrane-associated PDPK1 are required for stabilization of apical junctions, which promotes cell elongation, during epithelial morphogenesis.

  1. The metabolic/pH sensor soluble adenylyl cyclase is a tumor suppressor protein

    PubMed Central

    Ramos-Espiritu, Lavoisier; Diaz, Ana; Nardin, Charlee; Saviola, Anthony J.; Shaw, Fiona; Plitt, Tamar; Yang, Xia; Wolchok, Jedd; Pirog, Edyta C.; Desman, Garrett; Sboner, Andrea; Zhang, Tuo; Xiang, Jenny; Merghoub, Taha; Levin, Lonny R.; Buck, Jochen; Zippin, Jonathan H.

    2016-01-01

    cAMP signaling pathways can both stimulate and inhibit the development of cancer; however, the sources of cAMP important for tumorigenesis remain poorly understood. Soluble adenylyl cyclase (sAC) is a non-canonical, evolutionarily conserved, nutrient- and pH-sensing source of cAMP. sAC has been implicated in the metastatic potential of certain cancers, and it is differentially localized in human cancers as compared to benign tissues. We now show that sAC expression is reduced in many human cancers. Loss of sAC increases cellular transformation in vitro and malignant progression in vivo. These data identify the metabolic/pH sensor soluble adenylyl cyclase as a previously unappreciated tumor suppressor protein. PMID:27323809

  2. NOEY2 (ARHI), an imprinted putative tumor suppressor gene in ovarian and breast carcinomas

    PubMed Central

    Yu, Yinhua; Xu, Fengji; Peng, Hongqi; Fang, Xianjun; Zhao, Shulei; Li, Yang; Cuevas, Bruce; Kuo, Wen-Lin; Gray, Joe W.; Siciliano, Michael; Mills, Gordon B.; Bast, Robert C.

    1999-01-01

    Using differential display PCR, we have identified a gene [NOEY2, ARHI (designation by the Human Gene Nomenclature Committee)] with high homology to ras and rap that is expressed consistently in normal ovarian and breast epithelial cells but not in ovarian and breast cancers. Reexpression of NOEY2 through transfection suppresses clonogenic growth of breast and ovarian cancer cells. Growth suppression was associated with down-regulation of the cyclin D1 promoter activity and induction of p21WAF1/CIP1. In an effort to identify mechanisms leading to NOEY2 silencing in cancer, we found that the gene is expressed monoallelically and is imprinted maternally. Loss of heterozygosity of the gene was detected in 41% of ovarian and breast cancers. In most of cancer samples with loss of heterozygosity, the nonimprinted functional allele was deleted. Thus, NOEY2 appears to be a putative imprinted tumor suppressor gene whose function is abrogated in ovarian and breast cancers. PMID:9874798

  3. Identification of the von Hippel-Lindau disease tumor suppressor gene

    SciTech Connect

    Latif, F.; Masahiro Yao; Orcutt, L.; Kuzmin, I.; Fangwei Zhou; Zbar, B.; Lerman, M.I.; Dean, M. ); Tory, K.; Fuhmei Duh; Stackhouse, T.; Modi, W.; Geil, L.; Schmidt, L.; Hua Li; Ming Hui Wei; Fan Chen; Glavac, D. National Cancer Inst., Frederick, MD ); Gnarra, J.; Walther, M.M.; Yongkai Weng; Duan, D.S.R.; Linehan, W.M.; Glenn, G.; Choyke, P. ); Richards, F.M.; Crossey, P.A.; Ferguson-Smith, M.A.; Maher, E.R. ); Paslier D. Le; Chumakov, I.; Cohen, D. ); Chinault, A.C. )

    1993-05-28

    A gene discovered by positional cloning has been identified as the von Hippel-Lindau (VHL) disease tumor suppressor gene. A restriction fragment encompassing the gene showed rearrangements in 28 of 221 VHL kindreds. Eighteen of these rearrangements were due to deletions in the candidate gene, including three large nonoverlapping deletions. Intragenic mutations were detected in cell lines derived from VHL patients and from sporadic renal cell carcinomas. The VHL gene is evolutionarily conserved and encodes two widely expressed transcripts of approximately 6 and 6.5 kilobases. The partial sequence of the inferred gene product shows no homology to other proteins, except for an acidic repeat domain found in the procyclic surface membrane glycoprotein of Trypanosoma brucei. 17 refs., 4 figs. 1 tab.

  4. Frequent Attenuation of the WWOX Tumor Suppressor in Osteosarcoma is Associated with Increased Tumorigenicity and Aberrant RUNX2 Expression

    PubMed Central

    Kurek, Kyle; Del Mare, Sara; Salah, Zaidoun; Abdeen, Suhaib; Sadiq, Hussain; Lee, Sukhee; Gaudio, Eugenio; Zanesi, Nicola; Jones, Kevin B.; DeYoung, Barry; Amir, Gail; Gebhardt, Mark; Warman, Matthew; Stein, Gary S.; Stein, Janet L.; Lian, Jane B.; Aqeilan, Rami I.

    2011-01-01

    The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma (OS), an aggressive bone tumor with poor prognosis that often metastasizes to lung. On the basis of these observations, we examined the status of WWOX in human OS specimens and cell lines. In human OS clinical samples, WWOX expression was absent or reduced in 58% of tumors examined (P< 0.0001). Compared to the primary tumors, WWOX levels frequently increased in tumors resected following chemotherapy. In contrast, tumor metastases to lung often exhibited reduced WWOX levels, relative to the primary tumor. In human OS cell lines having reduced WWOX expression, ectopic expression of WWOX inhibited proliferation and attenuated invasion in vitro, and suppressed tumorgenicity in nude mice. Expression of WWOX was associated with reduced RUNX2 expression in OS cell lines, whereas Runx2 levels were elevated in femurs of Wwox-deficient mice. Furthermore, WWOX reconstitution in HOS cells was associated with downregulation of RUNX2 levels and RUNX2 target genes, consistent with the ability of WWOX to suppress RUNX2 transactivation activity. In clinical samples, RUNX2 was expressed in the majority of primary tumors and undetectable in most tumors resected following chemotherapy, whereas most metastases were RUNX2 positive. Our results deepen the evidence of a tumor suppressor role for WWOX in OS, furthering its prognostic and therapeutic significance in this disease. PMID:20530675

  5. Frequent attenuation of the WWOX tumor suppressor in osteosarcoma is associated with increased tumorigenicity and aberrant RUNX2 expression.

    PubMed

    Kurek, Kyle C; Del Mare, Sara; Salah, Zaidoun; Abdeen, Suhaib; Sadiq, Hussain; Lee, Suk-Hee; Gaudio, Eugenio; Zanesi, Nicola; Jones, Kevin B; DeYoung, Barry; Amir, Gail; Gebhardt, Mark; Warman, Matthew; Stein, Gary S; Stein, Janet L; Lian, Jane B; Aqeilan, Rami I

    2010-07-01

    The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma (OS), an aggressive bone tumor with poor prognosis that often metastasizes to lung. On the basis of these observations, we examined the status of WWOX in human OS specimens and cell lines. In human OS clinical samples, WWOX expression was absent or reduced in 58% of tumors examined (P < 0.0001). Compared with the primary tumors, WWOX levels frequently increased in tumors resected following chemotherapy. In contrast, tumor metastases to lung often exhibited reduced WWOX levels relative to the primary tumor. In human OS cell lines having reduced WWOX expression, ectopic expression of WWOX inhibited proliferation and attenuated invasion in vitro, and suppressed tumorigenicity in nude mice. Expression of WWOX was associated with reduced RUNX2 expression in OS cell lines, whereas RUNX2 levels were elevated in femurs of Wwox-deficient mice. Furthermore, WWOX reconstitution in HOS cells was associated with downregulation of RUNX2 levels and RUNX2 target genes, consistent with the ability of WWOX to suppress RUNX2 transactivation activity. In clinical samples, RUNX2 was expressed in the majority of primary tumors and undetectable in most tumors resected following chemotherapy, whereas most metastases were RUNX2 positive. Our results deepen the evidence of a tumor suppressor role for WWOX in OS, furthering its prognostic and therapeutic significance in this disease.

  6. From tamoxifen to dendrogenin A: The discovery of a mammalian tumor suppressor and cholesterol metabolite.

    PubMed

    Silvente-Poirot, Sandrine; de Medina, Philippe; Record, Michel; Poirot, Marc

    2016-11-01

    Tamoxifen (Tam) was developed as a ligand and modulator of estrogen receptor α (ERα) and is one of the main drugs used globally for the hormonotherapy of breast cancers. Besides ERα, Tam also binds with high affinity to the microsomal antiestrogen binding site (AEBS). The AEBS is a hetero-oligomeric proteinaceous complex with cholesterol-5,6-epoxide hydrolase (ChEH) activity that is associated with an intracellular histamine (HA) binding site. The enzymatic activities of the ChEH subunits control developmental programs in mammals and transform cholesterol-5,6-epoxides (5,6-EC) into cholestane-3β,5α,6β-triol. Inhibition of the ChEH activity by pharmacological agents such as Tam induce cancer cell re-differentiation through the accumulation of 5,6-EC. A few years ago, the putative chemical reactivity of the 5,6-EC epoxide group towards nucleophiles led our group to hypothesize that 5,6-EC could react with HA that was co-localized at the AEBS to give a new molecule involved in cell differentiation. This hypothesis was chemically tested and the conjugation of 5,6α-EC: with HA was found possible but only under catalytic conditions. It gave a stereo-selective single product of transformation which was named dendrogenin A (DDA). DDA was found to display potent cancer cell differentiation and anticancer properties in vitro and in vivo, suggesting that it was a tumor suppressor metabolite. The presence of DDA was then established in several mammalian tissues, providing the first evidence of a steroidal alkaloid metabolite in mammals. The discovery of DDA highlights a new metabolic pathway in mammals which lies at the crossroads of cholesterol and histamine metabolism and produces this tumor suppressor metabolite.

  7. Tumor suppressor microRNAs are downregulated in myelodysplastic syndrome with spliceosome mutations

    PubMed Central

    Aslan, Derya; Garde, Christian; Nygaard, Mette Katrine; Helbo, Alexandra Søgaard; Dimopoulos, Konstantinos; Hansen, Jakob Werner; Severinsen, Marianne Tang; Treppendahl, Marianne Bach; Sjø, Lene Dissing; Grønbæk, Kirsten; Kristensen, Lasse Sommer

    2016-01-01

    Spliceosome mutations are frequently observed in patients with myelodysplastic syndromes (MDS). However, it is largely unknown how these mutations contribute to the disease. MicroRNAs (miRNAs) are small noncoding RNAs, which have been implicated in most human cancers due to their role in post transcriptional gene regulation. The aim of this study was to analyze the impact of spliceosome mutations on the expression of miRNAs in a cohort of 34 MDS patients. In total, the expression of 76 miRNAs, including mirtrons and splice site overlapping miRNAs, was accurately quantified using reverse transcriptase quantitative PCR. The majority of the studied miRNAs have previously been implicated in MDS. Stably expressed miRNA genes for normalization of the data were identified using GeNorm and NormFinder algorithms. High-resolution melting assays covering all mutational hotspots within SF3B1, SRSF2, and U2AF1 (U2AF35) were developed, and all detected mutations were confirmed by Sanger sequencing. Overall, canonical miRNAs were downregulated in spliceosome mutated samples compared to wild-type (P = 0.002), and samples from spliceosome mutated patients clustered together in hierarchical cluster analyses. Among the most downregulated miRNAs were several tumor-suppressor miRNAs, including several let-7 family members, miR-423, and miR-103a. Finally, we observed that the predicted targets of the most downregulated miRNAs were involved in apoptosis, hematopoiesis, and acute myeloid leukemia among other cancer- and metabolic pathways. Our data indicate that spliceosome mutations may play an important role in MDS pathophysiology by affecting the expression of tumor suppressor miRNA genes involved in the development and progression of MDS. PMID:26848861

  8. Generation and Characterization of Mice Carrying a Conditional Allele of the Wwox Tumor Suppressor Gene

    PubMed Central

    Ludes-Meyers, John H.; Kil, Hyunsuk; Parker-Thornburg, Jan; Kusewitt, Donna F.; Bedford, Mark T.; Aldaz, C. Marcelo

    2009-01-01

    WWOX, the gene that spans the second most common human chromosomal fragile site, FRA16D, is inactivated in multiple human cancers and behaves as a suppressor of tumor growth. Since we are interested in understanding WWOX function in both normal and cancer tissues we generated mice harboring a conditional Wwox allele by flanking Exon 1 of the Wwox gene with LoxP sites. Wwox knockout (KO) mice were developed by breeding with transgenic mice carrying the Cre-recombinase gene under the control of the adenovirus EIIA promoter. We found that Wwox KO mice suffered from severe metabolic defect(s) resulting in growth retardation and all mice died by 3 wk of age. All Wwox KO mice displayed significant hypocapnia suggesting a state of metabolic acidosis. This finding and the known high expression of Wwox in kidney tubules suggest a role for Wwox in acid/base balance. Importantly, Wwox KO mice displayed histopathological and hematological signs of impaired hematopoeisis, leukopenia, and splenic atrophy. Impaired hematopoeisis can also be a contributing factor to metabolic acidosis and death. Hypoglycemia and hypocalcemia was also observed affecting the KO mice. In addition, bone metabolic defects were evident in Wwox KO mice. Bones were smaller and thinner having reduced bone volume as a consequence of a defect in mineralization. No evidence of spontaneous neoplasia was observed in Wwox KO mice. We have generated a new mouse model to inactivate the Wwox tumor suppressor gene conditionally. This will greatly facilitate the functional analysis of Wwox in adult mice and will allow investigating neoplastic transformation in specific target tissues. PMID:19936220

  9. PLK1 is a binding partner and a negative regulator of FOXO3 tumor suppressor

    PubMed Central

    Bucur, Octavian; Stancu, Andreea Lucia; Muraru, Maria Sinziana; Melet, Armelle; Petrescu, Stefana Maria; Khosravi-Far, Roya

    2015-01-01

    FOXO family members (FOXOs: FOXO1, FOXO3, FOXO4 and FOXO6) are important transcription factors and tumor suppressors controlling cell homeostasis and cell fate. They are characterized by an extraordinary functional diversity, being involved in regulation of cell cycle, proliferation, apoptosis, DNA damage response, oxidative detoxification, cell differentiation and stem cell maintenance, cell metabolism, angiogenesis, cardiac and other organ’s development, aging, and other critical cellular processes. FOXOs are tightly regulated by reversible phosphorylation, ubiquitination, acetylation and methylation. Interestingly, the known kinases phosphorylate only a small percentage of the known or predicted FOXOs phosphorylation sites, suggesting that additional kinases that phosphorylate and control FOXOs activity exist. In order to identify novel regulators of FOXO3, we have employed a proteomics screening strategy. Using HeLa cancer cell line and a Tandem Affinity Purification followed by Mass Spectrometry analysis, we identified several proteins as binding partners of FOXO3. Noteworthy, Polo Like Kinase 1 (PLK1) proto-oncogene was one of the identified FOXO3 binding partners. PLK1 plays a critical role during cell cycle (G2-M transition and all phases of mitosis) and in maintenance of genomic stability. Our experimental results presented in this manuscript demonstrate that FOXO3 and PLK1 exist in a molecular complex through most of the phases of the cell cycle, with a higher occurrence in the G2-M cell cycle phases. PLK1 induces translocation of FOXO3 from the nucleus to the cytoplasm and suppresses FOXO3 activity, measured by the decrease in the pro-apoptotic Bim protein levels and in the cell cycle inhibitor protein p27. Furthermore, PLK1 can directly phosphorylate FOXO3 in an in vitro kinase assay. These results present the discovery of PLK1 proto-oncogene as a binding partner and a negative regulator of FOXO3 tumor suppressor. PMID:26280018

  10. PLK1 is a binding partner and a negative regulator of FOXO3 tumor suppressor.

    PubMed

    Bucur, Octavian; Stancu, Andreea Lucia; Muraru, Maria Sinziana; Melet, Armelle; Petrescu, Stefana Maria; Khosravi-Far, Roya

    2014-01-01

    FOXO family members (FOXOs: FOXO1, FOXO3, FOXO4 and FOXO6) are important transcription factors and tumor suppressors controlling cell homeostasis and cell fate. They are characterized by an extraordinary functional diversity, being involved in regulation of cell cycle, proliferation, apoptosis, DNA damage response, oxidative detoxification, cell differentiation and stem cell maintenance, cell metabolism, angiogenesis, cardiac and other organ's development, aging, and other critical cellular processes. FOXOs are tightly regulated by reversible phosphorylation, ubiquitination, acetylation and methylation. Interestingly, the known kinases phosphorylate only a small percentage of the known or predicted FOXOs phosphorylation sites, suggesting that additional kinases that phosphorylate and control FOXOs activity exist. In order to identify novel regulators of FOXO3, we have employed a proteomics screening strategy. Using HeLa cancer cell line and a Tandem Affinity Purification followed by Mass Spectrometry analysis, we identified several proteins as binding partners of FOXO3. Noteworthy, Polo Like Kinase 1 (PLK1) proto-oncogene was one of the identified FOXO3 binding partners. PLK1 plays a critical role during cell cycle (G2-M transition and all phases of mitosis) and in maintenance of genomic stability. Our experimental results presented in this manuscript demonstrate that FOXO3 and PLK1 exist in a molecular complex through most of the phases of the cell cycle, with a higher occurrence in the G2-M cell cycle phases. PLK1 induces translocation of FOXO3 from the nucleus to the cytoplasm and suppresses FOXO3 activity, measured by the decrease in the pro-apoptotic Bim protein levels and in the cell cycle inhibitor protein p27. Furthermore, PLK1 can directly phosphorylate FOXO3 in an in vitro kinase assay. These results present the discovery of PLK1 proto-oncogene as a binding partner and a negative regulator of FOXO3 tumor suppressor.

  11. PTEN functions as a melanoma tumor suppressor by promoting host immune response.

    PubMed

    Dong, Y; Richards, J-Ae; Gupta, R; Aung, P P; Emley, A; Kluger, Y; Dogra, S K; Mahalingam, M; Wajapeyee, N

    2014-09-18

    Cancer cells acquire several traits that allow for their survival and progression, including the ability to evade the host immune response. However, the mechanisms by which cancer cells evade host immune responses remain largely elusive. Here we study the phenomena of immune evasion in malignant melanoma cells. We find that the tumor suppressor phosphatase and tensin homolog (PTEN) is an important regulator of the host immune response against melanoma cells. Mechanistically, PTEN represses the expression of immunosuppressive cytokines by blocking the phosphatidylinositide 3-kinase (PI3K) pathway. In melanoma cells lacking PTEN, signal transducer and activator of transcription 3 activates the transcription of immunosuppressive cytokines in a PI3K-dependent manner. Furthermore, conditioned media from PTEN-deficient, patient-derived short-term melanoma cultures and established melanoma cell lines blocked the production of the interleukin-12 (IL-12) in human monocyte-derived dendritic cells. Inhibition of IL-12 production was rescued by restoring PTEN or using neutralizing antibodies against the immunosuppressive cytokines. Furthermore, we report that PTEN, as an alternative mechanism to promote the host immune response against cancer cells, represses the expression of programmed cell death 1 ligand, a known repressor of the host immune response. Finally, to establish the clinical significance of our results, we analyzed malignant melanoma patient samples with or without brisk host responses. These analyses confirmed that PTEN loss is associated with a higher percentage of malignant melanoma samples with non-brisk host responses compared with samples with brisk host responses. Collectively, these results establish that PTEN functions as a melanoma tumor suppressor in part by regulating the host immune response against melanoma cells and highlight the importance of assessing PTEN status before recruiting melanoma patients for immunotherapies.

  12. LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast cancer

    SciTech Connect

    Ong, Danny C.T.; Rudduck, Christina; Chin, Koei; Kuo, Wen-Lin; Lie, Daniel K.H.; Chua, Constance L.M.; Wong, Chow Yin; Hong, Ga Sze; Gray, Joe; Lee, Ann S.G.

    2008-05-06

    Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We show here that LARG, from 11q23, has functional characteristics of a tumor suppressor. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, utilizing both loss of heterozygosity (LOH) analysis and microarray comparative genomic hybridization (CGH). LARG (also called ARHGEF12), identified from the analyzed region, was underexpressed in 34% of primary breast carcinomas and 80% of breast cancer cell lines including the MCF-7 line. Multiplex ligation-dependent probe amplification on 30 primary breast cancers and six breast cancer cell lines showed that LARG had the highest frequency of deletion compared to the BCSC-1 and TSLC1 genes, two known candidate tumor suppressor genes from 11q. In vitro analysis of breast cancer cell lines that underexpress LARG showed that LARG could be reactivated by trichostatin A, a histone deacetylase inhibitor, but not by 5-Aza-2{prime}-deoxycytidine, a demethylating agent. Bisulfite sequencing and quantitative high-throughput analysis of DNA methylation confirmed the lack of CpG island methylation in LARG in breast cancer. Restoration of LARG expression in MCF-7 cells by stable transfection resulted in reduced proliferation and colony formation, suggesting that LARG has functional characteristics of a tumor suppressor gene.

  13. PCR-RFLP to Detect Codon 248 Mutation in Exon 7 of "p53" Tumor Suppressor Gene

    ERIC Educational Resources Information Center

    Ouyang, Liming; Ge, Chongtao; Wu, Haizhen; Li, Suxia; Zhang, Huizhan

    2009-01-01

    Individual genome DNA was extracted fast from oral swab and followed up with PCR specific for codon 248 of "p53" tumor suppressor gene. "Msp"I restriction mapping showed the G-C mutation in codon 248, which closely relates to cancer susceptibility. Students learn the concepts, detection techniques, and research significance of point mutations or…

  14. The LKB1 tumor suppressor differentially affects anchorage independent growth of HPV positive cervical cancer cell lines

    SciTech Connect

    Mack, Hildegard I.D.; Munger, Karl

    2013-11-15

    Infection with high-risk human papillomaviruses is causally linked to cervical carcinogenesis. However, most lesions caused by high-risk HPV infections do not progress to cancer. Host cell mutations contribute to malignant progression but the molecular nature of such mutations is unknown. Based on a previous study that reported an association between liver kinase B1 (LKB1) tumor suppressor loss and poor outcome in cervical cancer, we sought to determine the molecular basis for this observation. LKB1-negative cervical and lung cancer cells were reconstituted with wild type or kinase defective LKB1 mutants and we examined the importance of LKB1 catalytic activity in known LKB1-regulated processes including inhibition of cell proliferation and elevated resistance to energy stress. Our studies revealed marked differences in the biological activities of two kinase defective LKB1 mutants in the various cell lines. Thus, our results suggest that LKB1 may be a cell-type specific tumor suppressor. - Highlights: • LKB1 is a tumor suppressor that is linked to Peutz-Jeghers syndrome. • Peutz-Jeghers syndrome patients have a high incidence of cervical cancer. • Cervical cancer is caused by HPV infections. • This study investigates LKB1 tumor suppressor activity in cervical cancer.

  15. Enhancement of the RAD51 Recombinase Activity by the Tumor Suppressor PALB2

    SciTech Connect

    Dray, Eloise; Etchin, Julia; Wiese, Claudia; Saro, Dorina; Williams, Gareth J.; Hammel, Michal; Yu, Xiong; Galkin, Vitold E.; Liu, Dongqing; Tsai, Miaw-Sheue; Sy, Shirley M-H.; Egelman, Edward; Chen, Junjie; Sung, Patrick; Schild, D.

    2010-08-24

    Homologous recombination mediated by the RAD51 recombinase helps eliminate chromosomal lesions, such as DNA double-stranded breaks induced by radiation or arising from injured DNA replication forks. The tumor suppressors BRCA2 and PALB2 act together to deliver RAD51 to chromosomal lesions to initiate repair. Here we document a new function of PALB2 in the enhancement of RAD51's ability to form the D-loop. We show that PALB2 binds DNA and physically interacts with RAD51. Importantly, while PALB2 alone stimulates D-loop formation, a cooperative effect is seen with RAD51AP1, an enhancer of RAD51. This stimulation stems from PALB2's ability to function with RAD51 and RAD51AP1 to assemble the synaptic complex. Our results help unveil a multi-faceted role of PALB2 in chromosome damage repair. Since PALB2 mutations can cause breast and other tumors or lead to Fanconi anemia, our findings are important for understanding the mechanism of tumor suppression in humans.

  16. Role of the WWOX tumor suppressor gene in bone homeostasis and the pathogenesis of osteosarcoma

    PubMed Central

    Del Mare, Sara; Kurek, Kyle C; Stein, Gary S; Lian, Jane B; Aqeilan, Rami I

    2011-01-01

    Osteosarcoma is the most common primary bone malignancy in children with unknown etiology and often with poor clinical outcome. In recent years, a critical role has emerged for the WW domain-containing oxidoreductase (WWOX) in osteosarcoma and bone biology. WWOX is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma and a bone metabolic disease characterized by hypocalcemia and osteopenia. Studies of human osteosarcomas have revealed that the WWOX gene is deleted in 30% of cases and WWOX protein is absent or reduced in ∼60% of tumors. Further, WWOX levels are attenuated in the majority of osteosarcoma cells, in which ectopic expression is associated with reduced proliferation, migration, invasion and tumorigenicity. At the molecular level, WWOX associates with RUNX2 and suppresses its transcriptional activity in osteoblasts and in cancer cells. This review provides new insights on the current knowledge of the spectrum of WWOX activities and future directions for the role of WWOX in bone biology and osteosarcoma. PMID:21731849

  17. Role of the WWOX tumor suppressor gene in bone homeostasis and the pathogenesis of osteosarcoma.

    PubMed

    Del Mare, Sara; Kurek, Kyle C; Stein, Gary S; Lian, Jane B; Aqeilan, Rami I

    2011-01-01

    Osteosarcoma is the most common primary bone malignancy in children with unknown etiology and often with poor clinical outcome. In recent years, a critical role has emerged for the WW domain-containing oxidoreductase (WWOX) in osteosarcoma and bone biology. WWOX is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma and a bone metabolic disease characterized by hypocalcemia and osteopenia. Studies of human osteosarcomas have revealed that the WWOX gene is deleted in 30% of cases and WWOX protein is absent or reduced in ∼60% of tumors. Further, WWOX levels are attenuated in the majority of osteosarcoma cells, in which ectopic expression is associated with reduced proliferation, migration, invasion and tumorigenicity. At the molecular level, WWOX associates with RUNX2 and suppresses its transcriptional activity in osteoblasts and in cancer cells. This review provides new insights on the current knowledge of the spectrum of WWOX activities and future directions for the role of WWOX in bone biology and osteosarcoma.

  18. PU.1 is a potent tumor suppressor in classical Hodgkin lymphoma cells.

    PubMed

    Yuki, Hiromichi; Ueno, Shikiko; Tatetsu, Hiro; Niiro, Hiroaki; Iino, Tadafumi; Endo, Shinya; Kawano, Yawara; Komohara, Yoshihiro; Takeya, Motohiro; Hata, Hiroyuki; Okada, Seiji; Watanabe, Toshiki; Akashi, Koichi; Mitsuya, Hiroaki; Okuno, Yutaka

    2013-02-07

    PU.1 has previously been shown to be down-regulated in classical Hodgkin lymphoma (cHL) cells via promoter methylation. We performed bisulfite sequencing and proved that the promoter region and the -17 kb upstream regulatory element of the PU.1 gene were highly methylated. To evaluate whether down-regulation of PU.1 is essential for the growth of cHL cells, we conditionally expressed PU.1 in 2 cHL cell lines, L428 and KM-H2. Overexpression of PU.1 induced complete growth arrest and apoptosis in both cell lines. Furthermore, in a Hodgkin lymphoma tumor xenograft model using L428 and KM-H2 cell lines, overexpression of PU.1 led to tumor regression or stable disease. Lentiviral transduction of PU.1 into primary cHL cells also induced apoptosis. DNA microarray analysis revealed that among genes related to cell cycle and apoptosis, p21 (CDKN1A) was highly up-regulated in L428 cells after PU.1 induction. Stable knockdown of p21 rescued PU.1-induced growth arrest in L428 cells, suggesting that the growth arrest and apoptosis observed are at least partially dependent on p21 up-regulation. These data strongly suggest that PU.1 is a potent tumor suppressor in cHL and that induction of PU.1 with demethylation agents and/or histone deacetylase inhibitors is worth exploring as a possible therapeutic option for patients with cHL.

  19. Mechanism regulating reactive oxygen species in tumor induced myeloid-derived suppressor cells1

    PubMed Central

    Corzo, Cesar A.; Cotter, Matthew J.; Cheng, Pingyan; Cheng, Fendong; Kusmartsev, Sergei; Sotomayor, Eduardo; Padhya, Tapan; McCaffrey, Thomas V.; McCaffrey, Judith C.; Gabrilovich, Dmitry I.

    2010-01-01

    Myeloid-derived suppressor cells (MDSC) are a major component of the immune suppressive network described in cancer and many other pathological conditions. Recent studies have demonstrated that one of the major mechanisms of MDSC-induced immune suppression is mediated by reactive oxygen species (ROS). However, the mechanism of this phenomenon remained unknown. In this study we observed a substantial up-regulation of ROS by MDSC in all of seven different tumor models and in patients with head and neck cancer. The increased ROS production by MDSC is mediated by up-regulated activity of NADPH oxidase (NOX2). MDSC from tumor-bearing mice had significantly higher expression of NOX2 subunits, primarily p47phox and gp91phox, compared to immature myeloid cells from tumor-free mice. Expression of NOX2 subunits in MDSC was controlled by the STAT3 transcription factor. In the absence of NOX2 activity, MDSC lost the ability to suppress T-cell responses and quickly differentiated into mature macrophages and dendritic cells. These findings expand our fundamental understanding of the biology of MDSC and may also open new opportunities for therapeutic regulation of these cells in cancer. PMID:19380816

  20. Mechanism regulating reactive oxygen species in tumor-induced myeloid-derived suppressor cells.

    PubMed

    Corzo, Cesar A; Cotter, Matthew J; Cheng, Pingyan; Cheng, Fendong; Kusmartsev, Sergei; Sotomayor, Eduardo; Padhya, Tapan; McCaffrey, Thomas V; McCaffrey, Judith C; Gabrilovich, Dmitry I

    2009-05-01

    Myeloid-derived suppressor cells (MDSC) are a major component of the immune suppressive network described in cancer and many other pathological conditions. Recent studies have demonstrated that one of the major mechanisms of MDSC-induced immune suppression is mediated by reactive oxygen species (ROS). However, the mechanism of this phenomenon remained unknown. In this study, we observed a substantial up-regulation of ROS by MDSC in all of seven different tumor models and in patients with head and neck cancer. The increased ROS production by MDSC is mediated by up-regulated activity of NADPH oxidase (NOX2). MDSC from tumor-bearing mice had significantly higher expression of NOX2 subunits, primarily p47(phox) and gp91(phox), compared with immature myeloid cells from tumor-free mice. Expression of NOX2 subunits in MDSC was controlled by the STAT3 transcription factor. In the absence of NOX2 activity, MDSC lost the ability to suppress T cell responses and quickly differentiated into mature macrophages and dendritic cells. These findings expand our fundamental understanding of the biology of MDSC and may also open new opportunities for therapeutic regulation of these cells in cancer.

  1. The nuclear transport receptor Importin-11 is a tumor suppressor that maintains PTEN protein.

    PubMed

    Chen, Muhan; Nowak, Dawid G; Narula, Navneet; Robinson, Brian; Watrud, Kaitlin; Ambrico, Alexandra; Herzka, Tali M; Zeeman, Martha E; Minderer, Matthias; Zheng, Wu; Ebbesen, Saya H; Plafker, Kendra S; Stahlhut, Carlos; Wang, Victoria M Y; Wills, Lorna; Nasar, Abu; Castillo-Martin, Mireia; Cordon-Cardo, Carlos; Wilkinson, John E; Powers, Scott; Sordella, Raffaella; Altorki, Nasser K; Mittal, Vivek; Stiles, Brendon M; Plafker, Scott M; Trotman, Lloyd C

    2017-03-06

    Phosphatase and tensin homologue (PTEN) protein levels are critical for tumor suppression. However, the search for a recurrent cancer-associated gene alteration that causes PTEN degradation has remained futile. In this study, we show that Importin-11 (Ipo11) is a transport receptor for PTEN that is required to physically separate PTEN from elements of the PTEN degradation machinery. Mechanistically, we find that the E2 ubiquitin-conjugating enzyme and IPO11 cargo, UBE2E1, is a limiting factor for PTEN degradation. Using in vitro and in vivo gene-targeting methods, we show that Ipo11 loss results in degradation of Pten, lung adenocarcinoma, and neoplasia in mouse prostate with aberrantly high levels of Ube2e1 in the cytoplasm. These findings explain the correlation between loss of IPO11 and PTEN protein in human lung tumors. Furthermore, we find that IPO11 status predicts disease recurrence and progression to metastasis in patients choosing radical prostatectomy. Thus, our data introduce the IPO11 gene as a tumor-suppressor locus, which is of special importance in cancers that still retain at least one intact PTEN allele.

  2. DLC-1 operates as a tumor suppressor gene in human non-small cell lung carcinomas.

    PubMed

    Yuan, Bao-Zhu; Jefferson, Amy M; Baldwin, Kimberly T; Thorgeirsson, Snorri S; Popescu, Nicholas C; Reynolds, Steven H

    2004-02-19

    The deleted in liver cancer (DLC-1) gene at chromosome 8p21-22 is altered mainly by genomic deletion or aberrant promoter methylation in a large number of human cancers such as breast, liver, colon and prostate and is known to have an inhibitory effect on breast and liver tumor cell growth. Given the high frequency of deletion involving region 8p21-22 in human non-small cell lung carcinoma (NSCLC), we examined alterations of DLC-1 in a series of primary tumors and tumor cell lines and tested effects of DLC-1 on tumor cell growth. A significant decrease or absence of the DLC-1 mRNA expression was found in 95% of primary NSCLC (20/21) and 58% of NSCLC cell lines (11/19). Transcriptional silencing of DLC-1 was primarily associated with aberrant DNA methylation, rather than genomic deletion as 5-aza-2'-deoxycytidine induced reactivation of DLC-1 expression in 82% (9/11) NSCLC cell lines showing downregulated DLC-1. It was further evidenced by an aberrant DLC-1 promoter methylation pattern, which was detected by Southern blotting in 73% (8/11) of NSCLC cell lines with downregulation of the gene. The transfer of DLC-1 into three DLC-1 negative cell lines caused a significant inhibition in cell proliferation and/or a decrease in colony formation. Furthermore, stable transfer of DLC-1 abolished tumorigenicity in nude mice of two cell lines, suggesting that DLC-1 plays a role in NSCLC by acting as a bona fide new tumor suppressor gene.

  3. Thioredoxin interacting protein (TXNIP) is a novel tumor suppressor in thyroid cancer

    PubMed Central

    2014-01-01

    Background Thyroid cancer is the most common endocrine malignancy, and many patients with metastatic differentiated thyroid cancer (DTC), poorly differentiated thyroid cancer (PDTC), and anaplastic thyroid cancer (ATC) fail to respond to conventional therapies, resulting in morbidity and mortality. Additional therapeutic targets and treatment options are needed for these patients. We recently reported that peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in ATC and confers an aggressive phenotype when overexpressed in DTC cells. Methods Microarray analysis was used to identify downstream targets of PPARγ in ATC cells. Western blot analysis and immunohistochemistry (IHC) were used to assess thioredoxin interacting protein (TXNIP) expression in thyroid cancer cell lines and primary tumor specimens. Retroviral transduction was used to generate ATC cell lines that overexpress TXNIP, and assays that assess glucose uptake, viable cell proliferation, and invasion were used to characterize the in vitro properties of these cells. An orthotopic thyroid cancer mouse model was used to assess the effect of TXNIP overexpression in ATC cell lines in vivo. Results Using microarray analysis, we show that TXNIP is highly upregulated when PPARγ is depleted from ATC cells. Using Western blot analysis and IHC, we show that DTC and ATC cells exhibit differential TXNIP expression patterns. DTC cell lines and patient tumors have high TXNIP expression in contrast to low or absent expression in ATC cell lines and tumors. Overexpression of TXNIP decreases the growth of HTh74 cells compared to vector controls and inhibits glucose uptake in the ATC cell lines HTh74 and T238. Importantly, TXNIP overexpression in T238 cells results in attenuated tumor growth and decreased metastasis in an orthotopic thyroid cancer mouse model. Conclusions Our findings indicate that TXNIP functions as a tumor suppressor in thyroid cells, and its downregulation is likely important in

  4. Cross-talk between myeloid-derived suppressor cells (MDSC), macrophages, and dendritic cells enhances tumor-induced immune suppression.

    PubMed

    Ostrand-Rosenberg, Suzanne; Sinha, Pratima; Beury, Daniel W; Clements, Virginia K

    2012-08-01

    The tumor microenvironment is a complex milieu of tumor and host cells. Host cells can include tumor-reactive T cells capable of killing tumor cells. However, more frequently the tumor and host components interact to generate a highly immune suppressive environment that frustrates T cell cytotoxicity and promotes tumor progression through a variety of immune and non-immune mechanisms. Myeloid-derived suppressor cells (MDSC) are a major host component contributing to the immune suppressive environment. In addition to their inherent immune suppressive function, MDSC amplify the immune suppressive activity of macrophages and dendritic cells via cross-talk. This article will review the cell-cell interactions used by MDSC to inhibit anti-tumor immunity and promote progression, and the role of inflammation in promoting cross-talk between MDSC and other cells in the tumor microenvironment.

  5. The human LIS1 is downregulated in hepatocellular carcinoma and plays a tumor suppressor function

    SciTech Connect

    Xing, Zhen; Tang, Xin; Gao, Yuan; Da, Liang; Song, Hai; Wang, Suiquan; Tiollais, Pierre; Li, Tsaiping; Zhao, Mujun

    2011-06-03

    Highlights: {yields} LIS1 mRNA and protein levels are decreased in 70% HCC tissues. {yields} Downregulation of LIS1 expression induces oncogenic transformation of QSG7701 and NIH3T3 cells in vitro and in vivo. {yields} LIS1 downregulation leads to mitotic errors including spindle and chromosome defects. {yields} Ectopic expression of LIS1 could significantly inhibit HCC cell proliferation and colony formation. {yields} Our results suggest that LIS1 plays a potential tumor suppressor role in the development and progression of HCC. -- Abstract: The human lissencephaly-1 gene (LIS1) is a disease gene responsible for Miller-Dieker lissencephaly syndrome (MDL). LIS1 gene is located in the region of chromosome 17p13.3 that is frequency deleted in MDL patients and in human liver cancer cells. However, the expression and significance of LIS1 in liver cancer remain unknown. Here, we investigated the expression of LIS1 in hepatocellular carcinoma (HCC) tissues by real-time PCR, Western blot, and immunohistochemistry. The results indicated that the mRNA and protein levels of LIS1 were downregulated in about 70% of HCC tissues, and this downregulation was significantly associated with tumor progression. Functional studies showed that the reduction of LIS1 expression in the normal human liver cell line QSG7701 or the mouse fibroblast cell line NIH3T3 by shRNA resulted in colony formation in soft agar and xenograft tumor formation in nude mice, demonstrating that a decrease in the LIS1 level can promote the oncogenic transformation of cells. We also observed that the phenotypes of LIS1-knockdown cells displayed various defective mitotic structures, suggesting that the mechanism by which reduced LIS1 levels results in tumorigenesis is associated with its role in mitosis. Furthermore, we demonstrated that ectopic expression of LIS1 could significantly inhibit HCC cell proliferation and colony formation. Our results suggest that LIS1 plays a potential tumor suppressor role in the

  6. Modification of an apparatus for tumor-suppressor protein crystal growth in the International Space Station

    NASA Astrophysics Data System (ADS)

    de Morais Mendonca Teles, Antonio

    Some human diseases as tumors are being studied continuously for the development of vaccines against them. And a way of doing that is by means of proteins research. There are some kinds of proteins, like the p53 and p73 proteins, which are tumor suppressors. There are other diseases such as A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases which are protein-related. The determination of how proteins geometrically order themselves, during its biological functions is very necessary to understand how a protein's structure affects its function, to design vaccines that intercede in tumor-protein activities and in other proteins related to those other diseases. The protein crystal growth in microgravity environment produces purer crystallization than on the ground, and it is a powerful tool to produce better vaccines. Several data have already been acquired using ground-based research and in spaceflight experiments aboard the Spacelab and Space Shuttle missions, and in the MIR and in the International Space Station (ISS). Here in this paper, I propose to be performed in the ISS Biological Research Facility (which is being developed), multiple crystal growth of proteins related to cancer (as tumors suppressors and oncoproteins), A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases, for the future obtaining of possible vaccines against them. I also propose a simple and practical equipment, a modification of the crystallization plates (which use a vapor diffusion technique) inside each cylinder of the Protein Crystallization Apparatus in Microgravity (PCAM), with multiple chambers with different sizes. Instead of using some chambers with the same size it is better to use several chambers with different sizes. Why is that? The answer is: the energy associated with the surface tension of the liquid in the chamber is directly related to the circle area of it. So, to minimize the total energy of the surface tension of a proteins liquid -making it more stable

  7. Unfurling of the band 4.1, ezrin, radixin, moesin (FERM) domain of the merlin tumor suppressor

    SciTech Connect

    Yogesha, S.D.; Sharff, Andrew J.; Giovannini, Marco; Bricogne, Gerard; Izard, Tina

    2014-10-02

    The merlin-1 tumor suppressor is encoded by the Neurofibromatosis-2 (Nf2) gene and loss-of-function Nf2 mutations lead to nervous system tumors in man and to several tumor types in mice. Merlin is an ERM (ezrin, radixin, moesin) family cytoskeletal protein that interacts with other ERM proteins and with components of cell-cell adherens junctions (AJs). Merlin stabilizes the links of AJs to the actin cytoskeleton. Thus, its loss destabilizes AJs, promoting cell migration and invasion, which in Nf2{sup +/-} mice leads to highly metastatic tumors. Paradoxically, the 'closed' conformation of merlin-1, where its N-terminal four-point-one, ezrin, radixin, moesin (FERM) domain binds to its C-terminal tail domain, directs its tumor suppressor functions. Here we report the crystal structure of the human merlin-1 head domain when crystallized in the presence of its tail domain. Remarkably, unlike other ERM head-tail interactions, this structure suggests that binding of the tail provokes dimerization and dynamic movement and unfurling of the F2 motif of the FERM domain. We conclude the 'closed' tumor suppressor conformer of merlin-1 is in fact an 'open' dimer whose functions are disabled by Nf2 mutations that disrupt this architecture.

  8. Modulator of Apoptosis 1 (MOAP-1) Is a Tumor Suppressor Protein Linked to the RASSF1A Protein*

    PubMed Central

    Law, Jennifer; Salla, Mohamed; Zare, Alaa; Wong, Yoke; Luong, Le; Volodko, Natalia; Svystun, Orysya; Flood, Kayla; Lim, Jonathan; Sung, Miranda; Dyck, Jason R. B.; Tan, Chong Teik; Su, Yu-Chin; Yu, Victor C.; Mackey, John; Baksh, Shairaz

    2015-01-01

    Modulator of apoptosis 1 (MOAP-1) is a BH3-like protein that plays key roles in cell death or apoptosis. It is an integral partner to the tumor suppressor protein, Ras association domain family 1A (RASSF1A), and functions to activate the Bcl-2 family pro-apoptotic protein Bax. Although RASSF1A is now considered a bona fide tumor suppressor protein, the role of MOAP-1 as a tumor suppressor protein has yet to be determined. In this study, we present several lines of evidence from cancer databases, immunoblotting of cancer cells, proliferation, and xenograft assays as well as DNA microarray analysis to demonstrate the role of MOAP-1 as a tumor suppressor protein. Frequent loss of MOAP-1 expression, in at least some cancers, appears to be attributed to mRNA down-regulation and the rapid proteasomal degradation of MOAP-1 that could be reversed utilizing the proteasome inhibitor MG132. Overexpression of MOAP-1 in several cancer cell lines resulted in reduced tumorigenesis and up-regulation of genes involved in cancer regulatory pathways that include apoptosis (p53, Fas, and MST1), DNA damage control (poly(ADP)-ribose polymerase and ataxia telangiectasia mutated), those within the cell metabolism (IR-α, IR-β, and AMP-activated protein kinase), and a stabilizing effect on microtubules. The loss of RASSF1A (an upstream regulator of MOAP-1) is one of the earliest detectable epigenetically silenced tumor suppressor proteins in cancer, and we speculate that the additional loss of function of MOAP-1 may be a second hit to functionally compromise the RASSF1A/MOAP-1 death receptor-dependent pathway and drive tumorigenesis. PMID:26269600

  9. Tumor-Derived Tissue Factor Aberrantly Activates Complement and Facilitates Lung Tumor Progression via Recruitment of Myeloid-Derived Suppressor Cells

    PubMed Central

    Han, Xiao; Zha, Haoran; Yang, Fei; Guo, Bo; Zhu, Bo

    2017-01-01

    The initiator of extrinsic coagulation, tissue factor (TF), and its non-coagulant isoform alternatively spliced TF (asTF) are closely associated with tumor development. In the tumor microenvironment, the role of TF-induced coagulation in tumor progression remains to be fully elucidated. Using TF-knockdown lung tumor cells, we showed that TF is the dominant component of procoagulant activity but is dispensable in the cellular biology of tumor cells. In a xenograft model, using immunohistochemical analysis and flow cytometry analysis of the tumor microenvironment, we demonstrated that TF-induced fibrin deposition, which is correlated with complement activation and myeloid-derived suppressor cell (MDSC) recruitment, is positively associated with tumor progression. C5aR antagonism blunted the effect of TF on tumor progression and decreased MDSC recruitment. In conclusion, our data suggested that in tumor microenvironment, TF-induced coagulation activated the complement system and subsequently recruited myeloid-derived suppressor cells to promote tumor growth, which brings new insights into the coagulation-induced complement activation within the tumor microenvironment during tumor progression. PMID:28106852

  10. Tumor-Derived Tissue Factor Aberrantly Activates Complement and Facilitates Lung Tumor Progression via Recruitment of Myeloid-Derived Suppressor Cells.

    PubMed

    Han, Xiao; Zha, Haoran; Yang, Fei; Guo, Bo; Zhu, Bo

    2017-01-19

    The initiator of extrinsic coagulation, tissue factor (TF), and its non-coagulant isoform alternatively spliced TF (asTF) are closely associated with tumor development. In the tumor microenvironment, the role of TF-induced coagulation in tumor progression remains to be fully elucidated. Using TF-knockdown lung tumor cells, we showed that TF is the dominant component of procoagulant activity but is dispensable in the cellular biology of tumor cells. In a xenograft model, using immunohistochemical analysis and flow cytometry analysis of the tumor microenvironment, we demonstrated that TF-induced fibrin deposition, which is correlated with complement activation and myeloid-derived suppressor cell (MDSC) recruitment, is positively associated with tumor progression. C5aR antagonism blunted the effect of TF on tumor progression and decreased MDSC recruitment. In conclusion, our data suggested that in tumor microenvironment, TF-induced coagulation activated the complement system and subsequently recruited myeloid-derived suppressor cells to promote tumor growth, which brings new insights into the coagulation-induced complement activation within the tumor microenvironment during tumor progression.

  11. Regulator of G protein signaling 6 is a novel suppressor of breast tumor initiation and progression

    PubMed Central

    Fisher, Rory A.

    2013-01-01

    Breast cancer is a large global health burden and the most frequently diagnosed malignancy in women worldwide. Here, we utilize RGS6− /− mice to interrogate the role of regulator of G protein signaling 6 (RGS6), localized to the ductal epithelium in mouse and human breast, as a novel tumor suppressor in vivo. RGS6− /− mice exhibit accelerated 7,12-dimethylbenza[α]anthracene (DMBA)-induced tumor initiation and progression, as well as decreased overall survival. Analysis of carcinogenic aberrations in the mammary glands of DMBA-treated mice revealed a failure of the DNA damage response concurrent with augmented oncogenesis in RGS6−/− animals. Furthermore, RGS6 suppressed cell growth induced by either human epidermal growth factor receptor 2 or estrogen receptor activation in both MCF-7 breast cancer cells and mammary epithelial cells (MECs). MECs isolated from RGS6−/− mice also showed a deficit in DMBA-induced ATM/p53 activation, reactive oxygen species generation and apoptosis confirming that RGS6 is required for effective activation of the DNA damage response in these cells, a critical countermeasure against carcinogen-mediated genotoxic stress. The ability of RGS6 to simultaneously enhance DNA-damage-induced apoptotic signaling and suppress oncogenic cell growth likely underlie the accelerated tumorigenesis and cellular transformation observed in DMBA-treated RGS6−/− mice and isolated MECs, respectively. Unsurprisingly, spontaneous tumor formation was also seen in old female RGS6−/− but not in wild-type mice. Our finding that RGS6 is downregulated in all human breast cancer subtypes independent of their molecular classification indicates that obtaining a means to restore the growth suppressive and pro-apoptotic actions of RGS6 in breast might be a viable means to treat a large spectrum of breast tumors. PMID:23598467

  12. Regulator of G protein signaling 6 is a novel suppressor of breast tumor initiation and progression.

    PubMed

    Maity, Biswanath; Stewart, Adele; O'Malley, Yunxia; Askeland, Ryan W; Sugg, Sonia L; Fisher, Rory A

    2013-08-01

    Breast cancer is a large global health burden and the most frequently diagnosed malignancy in women worldwide. Here, we utilize RGS6(-/-) mice to interrogate the role of regulator of G protein signaling 6 (RGS6), localized to the ductal epithelium in mouse and human breast, as a novel tumor suppressor in vivo. RGS6(-/-) mice exhibit accelerated 7,12-dimethylbenza[α]anthracene (DMBA)-induced tumor initiation and progression, as well as decreased overall survival. Analysis of carcinogenic aberrations in the mammary glands of DMBA-treated mice revealed a failure of the DNA damage response concurrent with augmented oncogenesis in RGS6(-/-) animals. Furthermore, RGS6 suppressed cell growth induced by either human epidermal growth factor receptor 2 or estrogen receptor activation in both MCF-7 breast cancer cells and mammary epithelial cells (MECs). MECs isolated from RGS6(-/-) mice also showed a deficit in DMBA-induced ATM/p53 activation, reactive oxygen species generation and apoptosis confirming that RGS6 is required for effective activation of the DNA damage response in these cells, a critical countermeasure against carcinogen-mediated genotoxic stress. The ability of RGS6 to simultaneously enhance DNA-damage-induced apoptotic signaling and suppress oncogenic cell growth likely underlie the accelerated tumorigenesis and cellular transformation observed in DMBA-treated RGS6(-/-) mice and isolated MECs, respectively. Unsurprisingly, spontaneous tumor formation was also seen in old female RGS6(-/-) but not in wild-type mice. Our finding that RGS6 is downregulated in all human breast cancer subtypes independent of their molecular classification indicates that obtaining a means to restore the growth suppressive and pro-apoptotic actions of RGS6 in breast might be a viable means to treat a large spectrum of breast tumors.

  13. Genistein Up-Regulates Tumor Suppressor MicroRNA-574-3p in Prostate Cancer

    PubMed Central

    Chiyomaru, Takeshi; Yamamura, Soichiro; Fukuhara, Shinichiro; Hidaka, Hideo; Majid, Shahana; Saini, Sharanjot; Arora, Sumit; Deng, Guoren; Shahryari, Varahram; Chang, Inik; Tanaka, Yuichiro; Tabatabai, Z. Laura; Enokida, Hideki; Seki, Naohiko; Nakagawa, Masayuki; Dahiya, Rajvir

    2013-01-01

    Genistein has been shown to inhibit cancers both in vitro and in vivo, by altering the expression of several microRNAs (miRNAs). In this study, we focused on tumor suppressor miRNAs regulated by genistein and investigated their function in prostate cancer (PCa) and target pathways. Using miRNA microarray analysis and real-time RT-PCR we observed that miR-574-3p was significantly up-regulated in PCa cells treated with genistein compared with vehicle control. The expression of miR-574-3p was significantly lower in PCa cell lines and clinical PCa tissues compared with normal prostate cells (RWPE-1) and adjacent normal tissues. Low expression level of miR-574-3p was correlated with advanced tumor stage and higher Gleason score in PCa specimens. Re-expression of miR-574-3p in PCa cells significantly inhibited cell proliferation, migration and invasion in vitro and in vivo. miR-574-3p restoration induced apoptosis through reducing Bcl-xL and activating caspase-9 and caspase-3. Using GeneCodis software analysis, several pathways affected by miR-574-3p were identified, such as ‘Pathways in cancer’, ‘Jak-STAT signaling pathway’, and ‘Wnt signaling pathway’. Luciferase reporter assays demonstrated that miR-574-3p directly binds to the 3′ UTR of several target genes (such as RAC1, EGFR and EP300) that are components of ‘Pathways in cancer’. Quantitative real-time PCR and Western analysis showed that the mRNA and protein expression levels of the three target genes in PCa cells were markedly down-regulated with miR-574-3p. Loss-of-function studies demonstrated that the three target genes significantly affect cell proliferation, migration and invasion in PCa cell lines. Our results show that genistein up-regulates tumor suppressor miR-574-3p expression targeting several cell signaling pathways. These findings enhance understanding of how genistein regulates with miRNA in PCa. PMID:23554959

  14. Cluster Analysis of Tumor Suppressor Genes in Canine Leukocytes Identifies Activation State

    PubMed Central

    Daly, Julie-Anne; Mortlock, Sally-Anne; Taylor, Rosanne M.; Williamson, Peter

    2015-01-01

    Cells of the immune system undergo activation and subsequent proliferation in the normal course of an immune response. Infrequently, the molecular and cellular events that underlie the mechanisms of proliferation are dysregulated and may lead to oncogenesis, leading to tumor formation. The most common forms of immunological cancers are lymphomas, which in dogs account for 8%–20% of all cancers, affecting up to 1.2% of the dog population. Key genes involved in negatively regulating proliferation of lymphocytes include a group classified as tumor suppressor genes (TSGs). These genes are also known to be associated with progression of lymphoma in humans, mice, and dogs and are potential candidates for pathological grading and diagnosis. The aim of the present study was to analyze TSG profiles in stimulated leukocytes from dogs to identify genes that discriminate an activated phenotype. A total of 554 TSGs and three gene set collections were analyzed from microarray data. Cluster analysis of three subsets of genes discriminated between stimulated and unstimulated cells. These included 20 most upregulated and downregulated TSGs, TSG in hallmark gene sets significantly enriched in active cells, and a selection of candidate TSGs, p15 (CDKN2B), p18 (CDKN2C), p19 (CDKN1A), p21 (CDKN2A), p27 (CDKN1B), and p53 (TP53) in the third set. Analysis of two subsets suggested that these genes or a subset of these genes may be used as a specialized PCR set for additional analysis. PMID:27478369

  15. Does Notch play a tumor suppressor role across diverse squamous cell carcinomas?

    PubMed

    Zhang, Min; Biswas, Sangita; Qin, Xin; Gong, Wenrong; Deng, Wenbing; Yu, Hongjun

    2016-08-01

    The role of Notch pathway in tumorigenesis is highly variable. It can be tumor suppressive or pro-oncogenic, typically depending on the cellular context. Squamous cell carcinoma (SCC) is a cancer of the squamous cell, which can occur in diverse human tissues. SCCs are one of the most frequent human malignancies for which the pathologic mechanisms remain elusive. Recent genomic analysis of diverse SCCs identified marked levels of mutations in NOTCH1, implicating Notch signaling pathways in the pathogenesis of SCCs. In this review, evidences highlighting NOTCH's role in different types of SCCs are summarized. Moreover, based on accumulating structural information of the NOTCH receptor, the functional consequences of NOTCH1 gene mutations identified from diverse SCCs are analyzed, emphasizing loss of function of Notch in these cancers. Finally, we discuss the convergent view on an intriguing possibility that Notch may function as tumor suppressor in SCCs across different tissues. These mechanistic insights into Notch signaling pathways will help to guide the research of SCCs and development of therapeutic strategies for these cancers.

  16. Tumor suppressor Lzap regulates cell cycle progression, doming and zebrafish epiboly

    PubMed Central

    Liu, Dan; Wang, Wen-Der; Melville, David B.; Cha, Yong I.; Yin, Zhirong; Issaeva, Natalia; Knapik, Ela W.; Yarbrough, Wendell G.

    2012-01-01

    Initial stages of embryonic development rely on rapid, synchronized cell divisions of the fertilized egg followed by a set of morphogenetic movements collectively called epiboly and gastrulation. Lzap is a putative tumor suppressor whose expression is lost in 30% of head and neck squamous cell carcinomas. Lzap activities include regulation of cell cycle progression and response to therapeutic agents. Here we explore developmental roles of the lzap gene during zebrafish morphogenesis. Lzap is highly conserved among vertebrates and is maternally deposited. Expression is initially ubiquitous during gastrulation, and later becomes more prominent in the pharyngeal arches, digestive tract and brain. Antisense morpholino-mediated depletion of Lzap resulted in delayed cell divisions and apoptosis during blastomere formation, resulting in fewer, larger cells. Cell cycle analysis suggested that Lzap loss in early embryonic cells resulted in a G2/M arrest. Furthermore, the Lzap-deficient embryos failed to initiate epiboly – the earliest morphogenetic movement in animal development – which has been shown to be dependent on cell adhesion and migration of epithelial sheets. Our results strongly implicate Lzap in regulation of cell cycle progression, adhesion and migratory activity of epithelial cell sheets during early development. These functions provide further insight into Lzap activity that may contribute not only to development, but also to tumor formation. PMID:21523853

  17. Hepatocellular carcinoma mouse models: Hepatitis B virus-associated hepatocarcinogenesis and haploinsufficient tumor suppressor genes

    PubMed Central

    Teng, Yuan-Chi; Shen, Zhao-Qing; Kao, Cheng-Heng; Tsai, Ting-Fen

    2016-01-01

    The multifactorial and multistage pathogenesis of hepatocellular carcinoma (HCC) has fascinated a wide spectrum of scientists for decades. While a number of major risk factors have been identified, their mechanistic roles in hepatocarcinogenesis still need to be elucidated. Many tumor suppressor genes (TSGs) have been identified as being involved in HCC. These TSGs can be classified into two groups depending on the situation with respect to allelic mutation/loss in the tumors: the recessive TSGs with two required mutated alleles and the haploinsufficient TSGs with one required mutated allele. Hepatitis B virus (HBV) is one of the most important risk factors associated with HCC. Although mice cannot be infected with HBV due to the narrow host range of HBV and the lack of a proper receptor, one advantage of mouse models for HBV/HCC research is the numerous and powerful genetic tools that help investigate the phenotypic effects of viral proteins and allow the dissection of the dose-dependent action of TSGs. Here, we mainly focus on the application of mouse models in relation to HBV-associated HCC and on TSGs that act either in a recessive or in a haploinsufficient manner. Discoveries obtained using mouse models will have a great impact on HCC translational medicine. PMID:26755878

  18. Tumor-Derived Suppressor of Fused Mutations Reveal Hedgehog Pathway Interactions.

    PubMed

    Urman, Nicole M; Mirza, Amar; Atwood, Scott X; Whitson, Ramon J; Sarin, Kavita Y; Tang, Jean Y; Oro, Anthony E

    2016-01-01

    The Hedgehog pathway is a potent regulator of cellular growth and plays a central role in the development of many cancers including basal cell carcinoma (BCC). The majority of BCCs arise from mutations in the Patched receptor resulting in constitutive activation of the Hedgehog pathway. Secondary driver mutations promote BCC oncogenesis and occur frequently due to the high mutational burden resulting from sun exposure of the skin. Here, we uncover novel secondary mutations in Suppressor of Fused (SUFU), the major negative regulator of the Hedgehog pathway. SUFU normally binds to a Hedgehog transcriptional activator, GLI1, in order to prevent it from initiating transcription of Hedgehog target genes. We sequenced tumor-normal pairs from patients with early sporadic BCCs. This resulted in the discovery of nine mutations in SUFU, which were functionally investigated to determine whether they help drive BCC formation. Our results show that four of the SUFU mutations inappropriately activate the Hedgehog pathway, suggesting they may act as driver mutations for BCC development. Indeed, all four of the loss of function SUFU variants were found to disrupt its binding to GLI, leading to constitutive pathway activation. Our results from functional characterization of these mutations shed light on SUFU's role in Hedgehog signaling, tumor progression, and highlight a way in which BCCs can arise.

  19. miR-203, a Tumor Suppressor Frequently Down-regulated by Promoter Hypermethylation in Rhabdomyosarcoma*

    PubMed Central

    Diao, Yarui; Guo, Xing; Jiang, Lei; Wang, Gang; Zhang, Chao; Wan, Jun; Jin, Yan; Wu, Zhenguo

    2014-01-01

    Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma found in children and young adults. It is characterized by the expression of a number of skeletal muscle-specific proteins, including MyoD and muscle α-actin. However, unlike normal myoblasts, RMS cells differentiate poorly both in vivo and in culture. As microRNAs are known to regulate tumorigenesis, intensive efforts have been made to identify microRNAs that are involved in RMS development. In this work, we found that miR-203 was frequently down-regulated by promoter hypermethylation in both RMS cell lines and RMS biopsies and could be reactivated by DNA-demethylating agents. Re-expression of miR-203 in RMS cells inhibited their migration and proliferation and promoted terminal myogenic differentiation. Mechanistically, miR-203 exerts its tumor-suppressive effect by directly targeting p63 and leukemia inhibitory factor receptor in RMS cells, which promotes myogenic differentiation by inhibiting the Notch and the JAK1/STAT1/STAT3 pathways, respectively. Our work reveals that miR-203 functions as a tumor suppressor in RMS development. PMID:24247238

  20. Expression of the tumor suppressor gene hypermethylated in cancer 1 in laryngeal carcinoma.

    PubMed

    Markowski, Jarosław; Sieroń, Aleksander L; Kasperczyk, Katarzyna; Ciupińska-Kajor, Monika; Auguściak-Duma, Aleksandra; Likus, Wirginia

    2015-05-01

    Hypermethylated in cancer 1 (HIC1) is a putative suppressor gene, cooperating with TP53 in the regulation of apoptosis. The promoter site of this gene contains CpG islands susceptible to methylation. Altered methylation leads to the silencing of HIC1. Persistent loss of HIC1 function reflects the attenuation of proapoptotic characteristics of TP53 and may constitute the background for carcinogenesis. Altered methylation profiles along with diminished expression of HIC1 were documented in a number of solid neoplasms. The aim of this study was to evaluate the expression of the HIC1 gene in laryngeal carcinoma. RNA was extracted from samples of laryngeal cancer and corresponding healthy tissues of 21 patients with advanced laryngeal cancer (T3-T4). The amount of RNA (cDNA) was evaluated using reverse transcription-quantitative polymerase chain reaction with GADPH as the reference gene. Data demonstrated that HIC1 expression was significantly reduced in laryngeal cancer tissues. The relative expression of HIC1 was found to be ~40% lower in tumor samples compared to that in healthy controls. The median tumor/normal tissue ratio for HIC1 was 0.615. These results suggest that low HIC1 expression may be associated with neoplastic transformation in the larynx.

  1. Expression of the tumor suppressor gene hypermethylated in cancer 1 in laryngeal carcinoma

    PubMed Central

    MARKOWSKI, JAROSŁAW; SIEROŃ, ALEKSANDER L.; KASPERCZYK, KATARZYNA; CIUPIŃSKA-KAJOR, MONIKA; AUGUŚCIAK-DUMA, ALEKSANDRA; LIKUS, WIRGINIA

    2015-01-01

    Hypermethylated in cancer 1 (HIC1) is a putative suppressor gene, cooperating with TP53 in the regulation of apoptosis. The promoter site of this gene contains CpG islands susceptible to methylation. Altered methylation leads to the silencing of HIC1. Persistent loss of HIC1 function reflects the attenuation of proapoptotic characteristics of TP53 and may constitute the background for carcinogenesis. Altered methylation profiles along with diminished expression of HIC1 were documented in a number of solid neoplasms. The aim of this study was to evaluate the expression of the HIC1 gene in laryngeal carcinoma. RNA was extracted from samples of laryngeal cancer and corresponding healthy tissues of 21 patients with advanced laryngeal cancer (T3-T4). The amount of RNA (cDNA) was evaluated using reverse transcription-quantitative polymerase chain reaction with GADPH as the reference gene. Data demonstrated that HIC1 expression was significantly reduced in laryngeal cancer tissues. The relative expression of HIC1 was found to be ~40% lower in tumor samples compared to that in healthy controls. The median tumor/normal tissue ratio for HIC1 was 0.615. These results suggest that low HIC1 expression may be associated with neoplastic transformation in the larynx. PMID:26137060

  2. The tumor suppressor protein menin inhibits AKT activation by regulating its cellular localization

    PubMed Central

    Wang, Yan; Ozawa, Atsushi; Zaman, Shadia; Prasad, Nijaguna B.; Chandrasekharappa, Settara C.; Agarwal, Sunita K.; Marx, Stephen J.

    2010-01-01

    Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder associated mainly with tumors of multiple endocrine organs. Mutations in the MEN1 gene that encodes for the menin protein are the predominant cause for hereditary MEN1 syndrome. Though menin is a tumor suppressor, its molecular mechanism of action has not been defined. Here we report that menin interacts with AKT1 in vitro and in vivo. Menin downregulates the level of active AKT and its kinase activity. Through interaction with AKT1, menin suppresses both AKT1 induced proliferation and anti-apoptosis in non-endocrine and endocrine cells. Confocal microscopy analysis revealed that menin regulates AKT1 in part by reducing the translocation of AKT1 from the cytoplasm to the plasma membrane during growth factor stimulation. Our findings may be generalizable to other cancers, insofar as we found that loss of menin expression was also associated with AKT activation in a mouse model of pancreatic islet adenoma. Together, our results suggest menin as an important novel negative regulator of AKT kinase activity. PMID:21127195

  3. The tumor suppressor, parafibromin, mediates histone H3 K9 methylation for cyclin D1 repression.

    PubMed

    Yang, Yong-Jin; Han, Jeung-Whan; Youn, Hong-Duk; Cho, Eun-Jung

    2010-01-01

    Parafibromin, a component of the RNA polymerase II-associated PAF1 complex, is a tumor suppressor linked to hyperparathyroidism-jaw tumor syndrome and sporadic parathyroid carcinoma. Parafibromin induces cell cycle arrest by repressing cyclin D1 via an unknown mechanism. Here, we show that parafibromin interacts with the histone methyltransferase, SUV39H1, and functions as a transcriptional repressor. The central region (128-227 amino acids) of parafibromin is important for both the interaction with SUV39H1 and transcriptional repression. Parafibromin associated with the promoter and coding regions of cyclin D1 and was required for the recruitment of SUV39H1 and the induction of H3 K9 methylation but not H3 K4 methylation. RNA interference analysis showed that SUV39H1 was critical for cyclin D1 repression. These data suggest that parafibromin plays an unexpected role as a repressor in addition to its widely known activity associated with transcriptional activation. Parafibromin as a part of the PAF1 complex might downregulate cyclin D1 expression by integrating repressive H3 K9 methylation during transcription.

  4. TCP10L acts as a tumor suppressor by inhibiting cell proliferation in hepatocellular carcinoma

    SciTech Connect

    Zuo, Jie; Cai, Hao; Wu, Yanhua; Ma, Haijie; Jiang, Wei; Liu, Chao; Han, Dingding; Ji, Guoqing; Yu, Long

    2014-03-28

    Highlights: • TCP10L was down-regulated in clinical hepatocellular carcinoma (HCC). • Expression of TCP10L correlated significantly with tumor size and Milan criteria. • Overexpression of TCP10L attenuated growth of HCC cells both in vitro and in vivo. • Knocking down TCP10L promoted cell proliferation and tumorigenesis of HCC cells. - Abstract: TCP10L (T-complex 10 (mouse)-like) has been identified as a liver and testis-specific gene. Although a potential transcriptional suppression function of TCP10L has been reported previously, biological function of this gene still remains largely elusive. In this study, we reported for the first time that TCP10L was significantly down-regulated in clinical hepatocellular carcinoma (HCC) samples when compared to the corresponding non-tumorous liver tissues. Furthermore, TCP10L expression was highly correlated with advanced cases exceeding the Milan criteria. Overexpression of TCP10L in HCC cells suppressed colony formation, inhibited cell cycle progression through G0/G1 phase, and attenuated cell growth in vivo. Consistently, silencing of TCP10L promoted cell cycle progression and cell growth. Therefore, our study has revealed a novel suppressor role of TCP10L in HCC, by inhibiting proliferation of HCC cells, which may facilitate the diagnosis and molecular therapy in HCC.

  5. Tumor-Derived Suppressor of Fused Mutations Reveal Hedgehog Pathway Interactions

    PubMed Central

    Urman, Nicole M.; Mirza, Amar; Atwood, Scott X.; Whitson, Ramon J.; Sarin, Kavita Y.; Tang, Jean Y.; Oro, Anthony E.

    2016-01-01

    The Hedgehog pathway is a potent regulator of cellular growth and plays a central role in the development of many cancers including basal cell carcinoma (BCC). The majority of BCCs arise from mutations in the Patched receptor resulting in constitutive activation of the Hedgehog pathway. Secondary driver mutations promote BCC oncogenesis and occur frequently due to the high mutational burden resulting from sun exposure of the skin. Here, we uncover novel secondary mutations in Suppressor of Fused (SUFU), the major negative regulator of the Hedgehog pathway. SUFU normally binds to a Hedgehog transcriptional activator, GLI1, in order to prevent it from initiating transcription of Hedgehog target genes. We sequenced tumor-normal pairs from patients with early sporadic BCCs. This resulted in the discovery of nine mutations in SUFU, which were functionally investigated to determine whether they help drive BCC formation. Our results show that four of the SUFU mutations inappropriately activate the Hedgehog pathway, suggesting they may act as driver mutations for BCC development. Indeed, all four of the loss of function SUFU variants were found to disrupt its binding to GLI, leading to constitutive pathway activation. Our results from functional characterization of these mutations shed light on SUFU’s role in Hedgehog signaling, tumor progression, and highlight a way in which BCCs can arise. PMID:28030567

  6. Identifying the ubiquitin ligase complex that regulates the NF1 tumor suppressor and Ras

    PubMed Central

    Hollstein, Pablo E.; Cichowski, Karen

    2013-01-01

    The NF1 tumor suppressor protein, neurofibromin, is a negative regulator of Ras. Neurofibromin is dynamically regulated by the proteasome and its degradation and re-expression are essential for maintaining appropriate levels of Ras-GTP. Like p53, NF1/neurofibromin can be inactivated in cancer by both mutations and excessive proteasomal destruction; however, little is known about the mechanisms that underlie this latter process. Here we show that a Cullin 3 (Cul3)/KBTBD7 complex controls both the regulated proteasomal degradation of neurofibromin and the pathogenic destabilization of neurofibromin in glioblastomas. Importantly RNAi-mediated Cul3 ablation and a dominant-negative Cul3 directly stabilize neurofibromin, suppress Ras and ERK, and inhibit proliferation in an NF1-dependent manner. Moreover, in glioblastomas where neurofibromin is chronically destabilized, Cul3 inhibition re-stabilizes the protein and suppresses tumor development. Collectively these studies demonstrate a previously unrecognized role for Cul3 in regulating Ras and provide a molecular framework that can be exploited to develop potential cancer therapies. PMID:23661552

  7. The von Hippel-Lindau tumor suppressor stabilizes novel plant homeodomain protein Jade-1.

    PubMed

    Zhou, Mina I; Wang, Hongmei; Ross, Jonathan J; Kuzmin, Igor; Xu, Chengen; Cohen, Herbert T

    2002-10-18

    The von Hippel-Lindau disease gene (VHL) is the causative gene for most adult renal cancers. However, the mechanism by which VHL protein functions as a renal tumor suppressor remains largely unknown. To identify low occupancy VHL protein partners with potential relevance to renal cancer, we screened a human kidney library against human VHL p30 using a yeast two-hybrid approach. Jade-1 (gene for Apoptosis and Differentiation in Epithelia) encodes a previously uncharacterized 64-kDa protein that interacts strongly with VHL protein and is most highly expressed in kidney. Jade-1 protein is short-lived and contains a candidate destabilizing (PEST) motif and plant homeodomains that are not required for the VHL interaction. Jade-1 is abundant in proximal tubule cells, which are clear-cell renal cancer precursors, and expression increases with differentiation. Jade-1 is expressed in cytoplasm and the nucleus diffusely and in speckles, where it partly colocalizes with VHL. VHL reintroduction into renal cancer cells increases endogenous Jade-1 protein abundance up to 10-fold. Furthermore, VHL increases Jade-1 protein half-life up to 3-fold. Thus, direct protein stabilization is identified as a new VHL function. Moreover, Jade-1 protein represents a novel candidate regulatory factor in VHL-mediated renal tumor suppression.

  8. Identification and characterization of a retinoid-induced class II tumor suppressor/growth regulatory gene.

    PubMed

    DiSepio, D; Ghosn, C; Eckert, R L; Deucher, A; Robinson, N; Duvic, M; Chandraratna, R A; Nagpal, S

    1998-12-08

    Retinoids, synthetic and natural analogs of retinoic acid, exhibit potent growth inhibitory and cell differentiation activities that account for their beneficial effects in treating hyperproliferative diseases such as psoriasis, actinic keratosis, and certain neoplasias. Tazarotene is a synthetic retinoid that is used in the clinic for the treatment of psoriasis. To better understand the mechanism of retinoid action in the treatment of hyperproliferative diseases, we used a long-range differential display-PCR to isolate retinoid-responsive genes from primary human keratinocytes. We have identified a cDNA, tazarotene-induced gene 3 (TIG3; Retinoic Acid Receptor Responder 3) showing significant homology to the class II tumor suppressor gene, H-rev 107. Tazarotene treatment increases TIG3 expression in primary human keratinocytes and in vivo in psoriatic lesions. Increased TIG3 expression is correlated with decreased proliferation. TIG3 is expressed in a number of tissues, and expression is reduced in cancer cell lines and some primary tumors. In breast cancer cell lines, retinoid-dependent TIG3 induction is observed in lines that are growth suppressed by retinoids but not in nonresponsive lines. Transient over-expression of TIG3 in T47D or Chinese hamster ovary cells inhibits colony expansion. Finally, studies in 293 cells expressing TIG3 linked to an inducible promoter demonstrated decreased proliferation with increased TIG3 levels. These studies suggest that TIG3 may be a growth regulator that mediates some of the growth suppressive effects of retinoids.

  9. Molecular pathology of pancreatic cancer: in quest of tumor suppressor genes.

    PubMed

    Furukawa, Toru; Horii, Akira

    2004-04-01

    To find molecular clues useful for early detection and effective therapy for pancreatic cancer, we first carried out genomic analysis by means of comparative genomic hybridization and micro-satellite analysis. We found very complicated molecular alterations in multiple chromosomal regions, including 1p, 6q, 9p, 12q, 17p, 18q, and 21q for losses and 8q and 20q for gains. These diverse changes are very characteristic of pancreatic cancer, and from this information, we developed a method for detecting the aberrant copy numbers of specific chromosomal regions by fluorescence in situ hybridization in cells collected from pancreatic juice for early diagnosis of pancreatic neoplasms. The regions of losses suggest the existence of tumor suppressor genes (TSGs). We identified DUSP6/MKP-3 at 12q21-q22 as a strong candidate TSG; it showed epigenetic inactivation in some fractions of invasive pancreatic cancer and growth suppression and apoptosis by overexpression in vitro. To determine the pathologic roles of 18q, we introduced a normal copy of chromosome 18 into cultured pancreatic cancer cells. The introduction induced marked suppressions of tumor formation and metastasis formation in vivo. We continue work to more completely understand the complex molecular mechanisms of pancreatic carcinogenesis and to apply the information gained to the clinical treatment of pancreatic cancer.

  10. Cell-Specific Modulation of Papovavirus Replication by Tumor Suppressor Protein p53

    PubMed Central

    Lepik, Dina; Ustav, Mart

    2000-01-01

    Small DNA tumor viruses like human papillomaviruses, simian virus 40, and adenoviruses modulate the activity of cellular tumor suppressor proteins p53 and/or pRB. These viruses replicate as nuclear multicopy extrachromosomal elements during the S phase of the cell cycle, and it has been suggested that inactivation of p53 and pRb is necessary for directing the cells to the S phase. Mouse polyomavirus (Py), however, modulates only the pRB protein activity without any obvious interference with the action of p53. We show here that Py replication was not suppressed by the p53 protein indeed in all tested different mouse cell lines. In addition, E1- and E2-dependent papillomavirus origin replication was insensitive to the action of p53 in mouse cells. We show that in hamster (Chinese hamster ovary) or human (osteosarcoma 143) cell lines the replication of both Py and papillomavirus origins was efficiently blocked by p53. The block of Py replication in human and hamster cells is not caused by the downregulation of large T-antigen expression. The deletion analysis of the p53 protein shows that the RPA binding, proline-rich regulatory, DNA-binding, and oligomerization domains are necessary for p53 action in both replication systems. These results indicate that in mouse cells the p53 protein could be inactive for the suppression of papovavirus replication. PMID:10775606

  11. Absence of p16INK4a and truncation of ARF tumor suppressors in chickens

    PubMed Central

    Kim, Soo-Hyun; Mitchell, Michael; Fujii, Hideta; Llanos, Susana; Peters, Gordon

    2003-01-01

    The INK4b-ARF-INK4a locus on human chromosome 9p21 (Human Genome Organization designation CDKN2B-CDKN2A), and the corresponding locus on mouse chromosome 4, encodes three distinct products: two members of the INK4 cyclin-dependent kinase inhibitor family and a completely unrelated protein, ARF, whose carboxyl-terminal half is specified by the second exon of INK4a but in an alternative reading frame. As INK4 proteins block the phosphorylation of the retinoblastoma gene product and ARF protects p53 from degradation, the locus plays a key role in tumor suppression and the control of cell proliferation. To gain further insights into the relative importance of INK4a and ARF in different settings, we have isolated and characterized the equivalent locus in chickens. Surprisingly, although we identified orthologues of INK4b and ARF, chickens do not encode an equivalent of INK4a. Moreover, the reading frame for chicken ARF does not extend into exon 2, because splicing occurs in a different register to that used in mammals. The resultant 60-aa product nevertheless shares functional attributes with its mammalian counterparts. As well as indicating that the locus has been subject to dynamic evolutionary pressures, these unexpected findings suggest that in chickens, the tumor-suppressor functions of INK4a have been compensated for by other genes. PMID:12506196

  12. HOXB1 Is a Tumor Suppressor Gene Regulated by miR-3175 in Glioma

    PubMed Central

    Han, Liang; Liu, Dehua; Li, Zhaohui; Tian, Nan; Han, Ziwu; Wang, Guang; Fu, Yao; Guo, Zhigang; Zhu, Zifeng

    2015-01-01

    The HOXB1 gene plays a critical role as an oncogene in diverse tumors. However, the functional role of HOXB1 and the mechanism regulating HOXB1 expression in glioma are not fully understood. A preliminary bioinformatics analysis showed that HOXB1 is ectopically expressed in glioma, and that HOXB1 is a possible target of miR-3175. In this study, we investigated the function of HOXB1 and the relationship between HOXB1 and miR-3175 in glioma. We show that HOXB1 expression is significantly downregulated in glioma tissues and cell lines, and that its expression may be closely associated with the degree of malignancy. Reduced HOXB1 expression promoted the proliferation and invasion of glioma cells, and inhibited their apoptosis in vitro, and the downregulation of HOXB1 was also associated with worse survival in glioma patients. More importantly, HOXB1 was shown experimentally to be a direct target of miR-3175 in this study. The downregulated expression of miR-3175 inhibited cell proliferation and invasion, and promoted apoptosis in glioma. The oncogenicity induced by low HOXB1 expression was prevented by an miR-3175 inhibitor in glioma cells. Our results suggest that HOXB1 functions as a tumor suppressor, regulated by miR-3175 in glioma. These results clarify the pathogenesis of glioma and offer a potential target for its treatment. PMID:26565624

  13. The ubiquitin E3 ligase ITCH enhances breast tumor progression by inhibiting the Hippo tumor suppressor pathway.

    PubMed

    Salah, Zaidoun; Itzhaki, Ella; Aqeilan, Rami I

    2014-11-15

    The Hippo kinase pathway is emerging as a conserved signaling pathway that is essential for organ growth and tumorigenesis. Recently, we reported that the ubiquitin E3 ligase ITCH negatively regulates LATS1, thereby increasing YAP activity, which leads to increased cell proliferation and decreased apoptosis. Here, we investigated the role of ITCH in breast tumorigenesis. In particular, we show that ITCH enhances epithelial-to-mesenchymal transition (EMT) through boosting YAP oncogenic function. By contrast, a point mutation in the catalytic domain or WW1 domain of ITCH abolished its EMT-mediated effects. Furthermore, while overexpression of ITCH expression in breast cells is associated with increased incidence of mammary tumor formation and progression, its knockdown inhibited breast cancer cell tumorigenicity and metastasis. Importantly, YAP knockdown was able to attenuate ITCH pro-tumorigenic functions. Lastly, we found that ITCH expression is significantly upregulated in invasive and metastatic breast cancer cases and is associated with worse survival. Together, our results reveal that ITCH pro-tumorigenic functions in breast cancer are mediated, at least in part, through inactivation of the Hippo tumor suppressor pathway.

  14. The ubiquitin E3 ligase ITCH enhances breast tumor progression by inhibiting the Hippo tumor suppressor pathway

    PubMed Central

    Salah, Zaidoun; Itzhaki, Ella; Aqeilan, Rami I

    2014-01-01

    The Hippo kinase pathway is emerging as a conserved signaling pathway that is essential for organ growth and tumorigenesis. Recently, we reported that the ubiquitin E3 ligase ITCH negatively regulates LATS1, thereby increasing YAP activity, which leads to increased cell proliferation and decreased apoptosis. Here, we investigated the role of ITCH in breast tumorigenesis. In particular, we show that ITCH enhances epithelial-to-mesenchymal transition (EMT) through boosting YAP oncogenic function. By contrast, a point mutation in the catalytic domain or WW1 domain of ITCH abolished its EMT-mediated effects. Furthermore, while overexpression of ITCH expression in breast cells is associated with increased incidence of mammary tumor formation and progression, its knockdown inhibited breast cancer cell tumorigenicity and metastasis. Importantly, YAP knockdown was able to attenuate ITCH pro-tumorigenic functions. Lastly, we found that ITCH expression is significantly upregulated in invasive and metastatic breast cancer cases and is associated with worse survival. Together, our results reveal that ITCH pro-tumorigenic functions in breast cancer are mediated, at least in part, through inactivation of the Hippo tumor suppressor pathway. PMID:25350971

  15. Targeting A Tumor Suppressor To Suppress Tumor Growth: News and Views on Protein Phosphatase 2A (PP2A) as a Target for Anti-cancer Therapy

    PubMed Central

    Perrotti, Danilo; Neviani, Paolo

    2013-01-01

    Protein phosphatase 2A (PP2A), one of the major serine-threonine phosphatases in mammalian cells, maintains cell homeostasis by counteracting most of the kinase-driven intracellular signaling pathways. Unrestrained activation of oncogenic kinases together with inhibition of tumor suppressors is frequently required for the development of cancer. Because it has been found genetically altered or functionally inactivated in many solid cancers and leukemias, PP2A is indeed a bona fide tumor suppressor. For example, the phosphatase activity of PP2A is suppressed in chronic myelogenous leukemia and other malignancies characterized by the aberrant activity of oncogenic kinases. Notably, preclinical studies indicate that pharmacologic restoration of PP2A tumor suppressor activity by PP2A activating drugs (PADs, e.g. FTY720) effectively antagonizes cancer development and progression. Herein, we systematically discuss the importance of PP2A as a druggable tumor suppressor in light of the possible introduction of PADs into anti-cancer therapeutic protocols. PMID:23639323

  16. Identification of Two Candidate Tumor Suppressor Genes on Chromosome l7p13.3: Assessment of their Roles in Breast and Ovarian Carcinogenesis

    DTIC Science & Technology

    2000-07-01

    also been reported in primitive neuroectodermal tumors , carcinoma of the cervix uteri, medulloblastoma, osteosarcoma, astrocytoma (22), and acute...AD______ GRANT NUMBER: DAMD17-96-1-6088 TITLE: Identification of Two Candidate Tumor Suppressor Genes on Chromosome 17p13.3: Assessment of their...Identification of Two Candidate Tumor Suppressor Genes on Chromosome 17 p13 .3 : Assessment of their Roles in Breast... DAMD17-96-1-6088 6. AUTHOR(S

  17. Identification of LZAP as a New Candidate Tumor Suppressor in Hepatocellular Carcinoma

    PubMed Central

    Zhao, Jing-jing; Pan, Ke; Li, Jian-jun; Chen, Yi-bing; Chen, Ju-gao; Lv, Lin; Wang, Dan-dan; Pan, Qiu-zhong; Chen, Min-shan; Xia, Jian-chuan

    2011-01-01

    Background LZAP was isolated as a binding protein of the Cdk5 activator p35. LZAP has been highly conserved during evolution and has been shown to function as a tumor suppressor in various cancers. This study aimed to investigate LZAP expression and its prognostic value in hepatocellular carcinoma (HCC). Meanwhile, the function of LZAP in hepatocarcinogenesis was further investigated in cell culture models and mouse models. Methods Real-time quantitative PCR, western blot and immunohistochemistry were used to explore LZAP expression in HCC cell lines and primary HCC clinical specimens. The functions of LZAP in the proliferation, colony formation, cell cycle, migration, invasion and apoptosis of HCC cell lines were also analyzed by infecting cells with an adenovirus containing full-length LZAP. The effect of LZAP on tumorigenicity in nude mice was also investigated. Results LZAP expression was significantly decreased in the tumor tissues and HCC cell lines. Clinicopathological analysis showed that LZAP expression was significantly correlated with tumor size, histopathological classification and serum α-fetoprotein (AFP). The Kaplan–Meier survival curves revealed that decreasing LZAP expression was associated with poor prognosis in HCC patients. LZAP expression was an independent prognostic marker of overall HCC patient survival in a multivariate analysis. The re-introduction of LZAP expression in the HepG2 and sk-Hep1 HCC cell lines significantly inhibited proliferation and colony formation in the HCC cells and induced G1 phase arrest and apoptosis of the HCC cells in vitro. Restoring LZAP expression in the HCC cell lines also inhibited migration and invasion. In addition, experiments with a mouse model revealed that LZAP overexpression could suppress HCC tumorigenicity in vivo. Conclusions Our data suggest that LZAP may play an important role in HCC progression and could be a potential molecular therapy target for HCC. PMID:22028922

  18. The von Hippel-Lindau tumor suppressor gene expression level has prognostic value in neuroblastoma.

    PubMed

    Hoebeeck, Jasmien; Vandesompele, Jo; Nilsson, Helén; De Preter, Katleen; Van Roy, Nadine; De Smet, Els; Yigit, Nurten; De Paepe, Anne; Laureys, Geneviève; Påhlman, Sven; Speleman, Frank

    2006-08-01

    Deletions of the short arm of chromosome 3 are often observed in a specific subset of aggressive neuroblastomas (NBs) with loss of distal 11q and without MYCN amplification. The critical deleted region encompasses the locus of the von Hippel-Lindau gene (VHL, 3p25). Constitutional loss of function mutations in the VHL gene are responsible for the VHL syndrome, a dominantly inherited familial cancer syndrome predisposing to a variety of neoplasms, including pheochromocytoma. Pheochromocytomas are, like NB, derived from neural crest cells, but, unlike NB, consist of more mature chromaffin cells instead of immature neuroblasts. Further arguments for a putative role of VHL in NB are its function as oxygen sensitizer and the reported relation between hypoxia and dedifferentiation of NB cells, leading to a more aggressive phenotype. To test the possible involvement of VHL in NB, we did mRNA expression analysis and sought evidence for VHL gene inactivation. Although no evidence for a classic tumor suppressor role for VHL in NB could be obtained, a strong correlation was observed between reduced levels of VHL mRNA and low patient survival probability (p=0.013). Furthermore, VHL appears to have predictive power in NTRK1 (TRKA) positive tumor samples with presumed favorable prognosis, which makes it a potentially valuable marker for more accurate risk assessment in this subgroup of patients. The significance of the reduced VHL expression levels in relation to NB tumor biology remains unexplained, as functional analysis demonstrated no clear effect of the reduction in VHL mRNA expression on protein stability of its downstream target hypoxia-inducible factor alpha.

  19. Tumor suppressor roles of CENP-E and Nsl1 in Drosophila epithelial tissues.

    PubMed

    Clemente-Ruiz, Marta; Muzzopappa, Mariana; Milán, Marco

    2014-01-01

    Depletion of spindle assembly checkpoint (SAC) genes in Drosophila epithelial tissues leads to JNK-dependent programmed cell death and additional blockade of the apoptotic program drives tumorigenesis. A recent report proposes that chromosomal instability (CIN) is not the driving force in the tumorigenic response of the SAC-deficient tissue, and that checkpoint proteins exert a SAC-independent tumor suppressor role. This notion is based on observations that the depletion of CENP-E levels or prevention of Bub3 from binding to the kinetochore in Drosophila tissues unable to activate the apoptotic program induces CIN but does not cause hyperproliferation. Here we re-examined this proposal. In contrast to the previous report, we observed that depletion of CENP-E or Nsl1-the latter mediating kinetochore targeting of Bub3-in epithelial tissues unable to activate the apoptotic program induces significant levels of aneuploidy and drives tumor-like growth. The induction of the JNK transcriptional targets Wingless, a mitogenic molecule, and MMP1, a matrix metaloproteinase 1 involved in basement membrane degradation was also observed in these tumors. An identical response of the tissue was previously detected upon depletion of several SAC genes or genes involved in spindle assembly, chromatin condensation, and cytokinesis, all of which have been described to cause CIN. All together, these results reinforce the role of CIN in driving tumorigenesis in Drosophila epithelial tissues and question the proposed SAC-independent roles of checkpoint proteins in suppressing tumorigenesis. Differences in aneuploidy rates might explain the discrepancy between the previous report and our results.

  20. Identification of new mutations in the NF2 tumor suppressor gene in schwannomas

    SciTech Connect

    Guida, M.; Welling, B.; Prior, T.W.

    1994-09-01

    Neurofibromatosis type 2 (NF2) is a severe genetic disorder with an incidence of approximately 1 in 40,000 individuals and is characterized by the formation of multiple benign nervous system tumors. The clinical hallmark of NF2 is the bilateral occurrence of schwannomas on the eighth cranial nerve (vestibular schwannomas). Recently, it has been shown that loss or inactivation of a tumor suppressor gene located in chromosome band 22q12 is the molecular cause of NF2 tumorigenesis. Also, mutations in the NF2 gene have now been identified in patients with sporadic vestibular schwannomas (unilateral schwannomas). We have completed the screening of 80% of the NF2 coding sequence of DNA from 13 sporadic schwannomas and 2 schwannomas from NF2 patients. Using heteroduplex analysis and direct sequencing, we found 13 novel mutations located in 7 different exons with a small cluster (46% of the mutations) located in the central portion of the gene. All of the mutations were unique to single patients. In three tumors, both NF2 alleles were mutated. The types of mutations found include: small deletions ranging from 1 to 30 base pairs, nonsense mutations, a single missense mutation and a splice donor site alteration. It appears that small deletions are the most common type of NF2 gene mutation. We also have developed a dosage test based on quantitative PCR and hybridization with specific probes to detect the loss of heterozygosity. We found that 7 out of 15 schwannomas (47%) show loss of heterozygosity. We are currently extending the analysis to all of the NF2 exons and DNA from 60 additional schwannomas.

  1. Patterns of somatic uniparental disomy identify novel tumor suppressor genes in colorectal cancer.

    PubMed

    Torabi, Keyvan; Miró, Rosa; Fernández-Jiménez, Nora; Quintanilla, Isabel; Ramos, Laia; Prat, Esther; del Rey, Javier; Pujol, Núria; Killian, J Keith; Meltzer, Paul S; Fernández, Pedro Luis; Ried, Thomas; Lozano, Juan José; Camps, Jordi; Ponsa, Immaculada

    2015-10-01

    Colorectal cancer (CRC) is characterized by specific patterns of copy number alterations (CNAs), which helped with the identification of driver oncogenes and tumor suppressor genes (TSGs). More recently, the usage of single nucleotide polymorphism arrays provided information of copy number neutral loss of heterozygosity, thus suggesting the occurrence of somatic uniparental disomy (UPD) and uniparental polysomy (UPP) events. The aim of this study is to establish an integrative profiling of recurrent UPDs/UPPs and CNAs in sporadic CRC. Our results indicate that regions showing high frequencies of UPD/UPP mostly coincide with regions typically involved in genomic losses. Among them, chromosome arms 3p, 5q, 9q, 10q, 14q, 17p, 17q, 20p, 21q and 22q preferentially showed UPDs/UPPs over genomic losses suggesting that tumor cells must maintain the disomic state of certain genes to favor cellular fitness. A meta-analysis using over 300 samples from The Cancer Genome Atlas confirmed our findings. Several regions affected by recurrent UPDs/UPPs contain well-known TSGs, as well as novel candidates such as ARID1A, DLC1, TCF7L2 and DMBT1. In addition, VCAN, FLT4, SFRP1 and GAS7 were also frequently involved in regions of UPD/UPP and displayed high levels of methylation. Finally, sequencing and fluorescence in situ hybridization analysis of the gene APC underlined that a somatic UPD event might represent the second hit to achieve biallelic inactivation of this TSG in colorectal tumors. In summary, our data define a profile of somatic UPDs/UPPs in sporadic CRC and highlights the importance of these events as a mechanism to achieve the inactivation of TSGs.

  2. The Opportunity of Precision Medicine for Breast Cancer with Context-Sensitive Tumor Suppressor Maspin.

    PubMed

    Bernardo, Margarida M; Dzinic, Sijana H; Matta, Maria J; Dean, Ivory; Saker, Lina; Sheng, Shijie

    2017-03-06

    To improve the precision of molecular diagnosis and to develop and guide targeted therapies of breast cancer, it is essential to determine mechanisms that underlie the specific tumor phenotypes. To this end, the application of a snapshot of gene expression profile for breast cancer diagnosis and prognosis is fundamentally challenged since the tissue-based data are derived from heterogonous cell types and are not likely to reflect the dynamics of context-dependent tumor progression and drug sensitivity. The intricate network of epithelial differentiation program can be concertedly controlled by tumor suppressor maspin, a homologue of clade B serine protease inhibitors (serpin), through its multifaceted molecular interactions in multiple subcellular localizations. Unlike most other serpins that are expressed in multiple and cell types, maspin is epithelial specific and has distinct roles in luminal and myoepithelial cells. Endogenously expressed maspin has been found in the nucleus and cytoplasm, and detected on the surface of cell membrane. It is also secreted free and as an exosomal cargo protein. Research in the field has led to the identification of the maspin targets and maspin-associated molecules, as well as the structural determinants of its suppressive functions. The current review discusses the possibility for maspin to serve as a cell type-specific and context-sensitive marker to improve the precision of breast cancer diagnosis and prognosis. These advancements further suggest a new window of opportunity for designing novel maspin-based chemotherapeutic agents with improved anti-cancer potency. This article is protected by copyright. All rights reserved.

  3. Patterns of somatic uniparental disomy identify novel tumor suppressor genes in colorectal cancer

    PubMed Central

    Torabi, Keyvan; Miró, Rosa; Fernández-Jiménez, Nora; Quintanilla, Isabel; Ramos, Laia; Prat, Esther; del Rey, Javier; Pujol, Núria; Killian, J. Keith; Meltzer, Paul S.; Fernández, Pedro Luis; Ried, Thomas; Lozano, Juan José; Camps, Jordi; Ponsa, Immaculada

    2015-01-01

    Colorectal cancer (CRC) is characterized by specific patterns of copy number alterations (CNAs), which helped with the identification of driver oncogenes and tumor suppressor genes (TSGs). More recently, the usage of single nucleotide polymorphism arrays provided information of copy number neutral loss of heterozygosity, thus suggesting the occurrence of somatic uniparental disomy (UPD) and uniparental polysomy (UPP) events. The aim of this study is to establish an integrative profiling of recurrent UPDs/UPPs and CNAs in sporadic CRC. Our results indicate that regions showing high frequencies of UPD/UPP mostly coincide with regions typically involved in genomic losses. Among them, chromosome arms 3p, 5q, 9q, 10q, 14q, 17p, 17q, 20p, 21q and 22q preferentially showed UPDs/UPPs over genomic losses suggesting that tumor cells must maintain the disomic state of certain genes to favor cellular fitness. A meta-analysis using over 300 samples from The Cancer Genome Atlas confirmed our findings. Several regions affected by recurrent UPDs/UPPs contain well-known TSGs, as well as novel candidates such as ARID1A, DLC1, TCF7L2 and DMBT1. In addition, VCAN, FLT4, SFRP1 and GAS7 were also frequently involved in regions of UPD/UPP and displayed high levels of methylation. Finally, sequencing and fluorescence in situ hybridization analysis of the gene APC underlined that a somatic UPD event might represent the second hit to achieve biallelic inactivation of this TSG in colorectal tumors. In summary, our data define a profile of somatic UPDs/UPPs in sporadic CRC and highlights the importance of these events as a mechanism to achieve the inactivation of TSGs. PMID:26243311

  4. Effect of cytostatic proline rich polypeptide-1 on tumor suppressors of inflammation pathway signaling in chondrosarcoma

    PubMed Central

    Galoian, Karina; Luo, Shihua; Qureshi, Amir; Patel, Parthik; Price, Rachel; Morse, Ashlyn S.; Chailyan, Gor; Abrahamyan, Silva; Temple, H. T.

    2016-01-01

    Cytokines produced in the tumour microenvironment exert an important role in cancer pathogenesis and in the inhibition of disease progression. Cancer of the cartilage is termed metastatic chondrosarcoma; however, the signaling events resulting in mesenchymal cell transformation to sarcoma have yet to be fully elucidated. The present study aimed to characterize the cytokine expression profile in the human JJ012 chondrosarcoma cell line, as well as the effect of cytostatic proline-rich polypeptide-1 (PRP-1). Western blot experiments demonstrated that the levels of suppressor of cytokine signaling 3 (SOCS3) were upregulated in chondrocytes compared with chondrosarcoma cells. Addition of PRP-1 restored the expression of the tumor suppressors, SOCS3 and ten-eleven-translocation methylcytosine dioxygenase 1 and 2 (TET1/2), in a dose-responsive manner. It is known that methylation of histone H3K9 was eliminated from the promoters of the inflammation-associated genes. PRP-1 inhibited H3K9 demethylase activity with an IC50 (concentration required to give half-maximal inhibition) value of 3.72 µg/ml in the chondrosarcoma cell line. Data obtained from ELISA experiments indicated that the expression of interleukin-6 (IL-6) in chondrosarcoma cells was 86-fold lower compared with that in C28 chondrocytes. In the present study, a 53-fold downregulation of IL-6 expression in co-culture of chondrosarcoma cells and C28 chondrocytes was identified as well. Downregulation of IL-6 expression has been documented in numerous other tumor types, although the reasons for this have not been fully established. In chondrosarcoma, IL-6 manifests itself as an anti-inflammatory agent and, possibly, as an anti-tumorigenic factor. To explore protein-DNA interactions leading to such differences, a gel-shift chemiluminescent assay was performed. Gel shifts were observed for chondrosarcoma and chondrocytes in the lanes that contained nuclear cell extract and oligo-IL-6 DNA. Notably, the DNA

  5. Hypermethylation of the tumor suppressor gene PRDM1/Blimp-1 supports a pathogenetic role in EBV-positive Burkitt lymphoma.

    PubMed

    Zhang, T; Ma, J; Nie, K; Yan, J; Liu, Y; Bacchi, C E; Queiroga, E M; Gualco, G; Sample, J T; Orazi, A; Knowles, D M; Tam, W

    2014-11-07

    PRDM1/Blimp-1 is a tumor suppressor gene in the activated B-cell subtype of diffuse large B-cell lymphomas. Its inactivation contributes to pathogenesis in this setting by impairing terminal B-cell differentiation induced by constitutive nuclear factor-κB activation. The role of PRDM1 in Burkitt lymphoma (BL) lymphomagenesis is not known. Here we identified hypermethylation of the promoter region and exon 1 of PRDM1 in all six Epstein-Barr virus (EBV)-positive BL cell lines and 12 of 23 (52%) primary EBV-positive BL or BL-related cases examined, but in none of the EBV-negative BL cell lines or primary tumors that we assessed, implying a tumor suppressor role for PRDM1 specifically in EBV-associated BL. A direct induction of PRDM1 hypermethylation by EBV is unlikely, as PRDM1 hypermethylation was not observed in EBV-immortalized B lymphoblastoid cell lines. Treatment of EBV-positive BL cells with 5' azacytidine resulted in PRDM1 induction associated with PRDM1 demethylation, consistent with transcriptional silencing of PRDM1 as a result of DNA methylation. Overexpression of PRDM1 in EBV-positive BL cell lines resulted in cell cycle arrest. Our results expand the spectrum of lymphoid malignancies in which PRDM1 may have a tumor suppressor role and identify an epigenetic event that likely contributes to the pathogenesis of BL.

  6. Hypermethylation of the tumor suppressor gene PRDM1/Blimp-1 supports a pathogenetic role in EBV-positive Burkitt lymphoma

    PubMed Central

    Zhang, T; Ma, J; Nie, K; Yan, J; Liu, Y; Bacchi, C E; Queiroga, E M; Gualco, G; Sample, J T; Orazi, A; Knowles, D M; Tam, W

    2014-01-01

    PRDM1/Blimp-1 is a tumor suppressor gene in the activated B-cell subtype of diffuse large B-cell lymphomas. Its inactivation contributes to pathogenesis in this setting by impairing terminal B-cell differentiation induced by constitutive nuclear factor-κB activation. The role of PRDM1 in Burkitt lymphoma (BL) lymphomagenesis is not known. Here we identified hypermethylation of the promoter region and exon 1 of PRDM1 in all six Epstein–Barr virus (EBV)-positive BL cell lines and 12 of 23 (52%) primary EBV-positive BL or BL-related cases examined, but in none of the EBV-negative BL cell lines or primary tumors that we assessed, implying a tumor suppressor role for PRDM1 specifically in EBV-associated BL. A direct induction of PRDM1 hypermethylation by EBV is unlikely, as PRDM1 hypermethylation was not observed in EBV-immortalized B lymphoblastoid cell lines. Treatment of EBV-positive BL cells with 5′ azacytidine resulted in PRDM1 induction associated with PRDM1 demethylation, consistent with transcriptional silencing of PRDM1 as a result of DNA methylation. Overexpression of PRDM1 in EBV-positive BL cell lines resulted in cell cycle arrest. Our results expand the spectrum of lymphoid malignancies in which PRDM1 may have a tumor suppressor role and identify an epigenetic event that likely contributes to the pathogenesis of BL. PMID:25382611

  7. A single-copy Sleeping Beauty transposon mutagenesis screen identifies new PTEN-cooperating tumor suppressor genes.

    PubMed

    de la Rosa, Jorge; Weber, Julia; Friedrich, Mathias Josef; Li, Yilong; Rad, Lena; Ponstingl, Hannes; Liang, Qi; de Quirós, Sandra Bernaldo; Noorani, Imran; Metzakopian, Emmanouil; Strong, Alexander; Li, Meng Amy; Astudillo, Aurora; Fernández-García, María Teresa; Fernández-García, María Soledad; Hoffman, Gary J; Fuente, Rocío; Vassiliou, George S; Rad, Roland; López-Otín, Carlos; Bradley, Allan; Cadiñanos, Juan

    2017-03-20

    The overwhelming number of genetic alterations identified through cancer genome sequencing requires complementary approaches to interpret their significance and interactions. Here we developed a novel whole-body insertional mutagenesis screen in mice, which was designed for the discovery of Pten-cooperating tumor suppressors. Toward this aim, we coupled mobilization of a single-copy inactivating Sleeping Beauty transposon to Pten disruption within the same genome. The analysis of 278 transposition-induced prostate, breast and skin tumors detected tissue-specific and shared data sets of known and candidate genes involved in cancer. We validated ZBTB20, CELF2, PARD3, AKAP13 and WAC, which were identified by our screens in multiple cancer types, as new tumor suppressor genes in prostate cancer. We demonstrated their synergy with PTEN in preventing invasion in vitro and confirmed their clinical relevance. Further characterization of Wac in vivo showed obligate haploinsufficiency for this gene (which encodes an autophagy-regulating factor) in a Pten-deficient context. Our study identified complex PTEN-cooperating tumor suppressor networks in different cancer types, with potential clinical implications.

  8. PERK Is a Haploinsufficient Tumor Suppressor: Gene Dose Determines Tumor-Suppressive Versus Tumor Promoting Properties of PERK in Melanoma

    PubMed Central

    Mackiewicz, Katarzyna; Katlinskaya, Yuliya V.; Staschke, Kirk A.; Paredes, Maria C. G.; Yoshida, Akihiro; Qie, Shuo; Zhang, Gao; Chajewski, Olga S.; Majsterek, Ireneusz; Herlyn, Meenhard; Fuchs, Serge Y.; Diehl, J. Alan

    2016-01-01

    The unfolded protein response (UPR) regulates cell fate following exposure of cells to endoplasmic reticulum stresses. PERK, a UPR protein kinase, regulates protein synthesis and while linked with cell survival, exhibits activities associated with both tumor progression and tumor suppression. For example, while cells lacking PERK are sensitive to UPR-dependent cell death, acute activation of PERK triggers both apoptosis and cell cycle arrest, which would be expected to contribute tumor suppressive activity. We have evaluated these activities in the BRAF-dependent melanoma and provide evidence revealing a complex role for PERK in melanoma where a 50% reduction is permissive for BrafV600E-dependent transformation, while complete inhibition is tumor suppressive. Consistently, PERK mutants identified in human melanoma are hypomorphic with dominant inhibitory function. Strikingly, we demonstrate that small molecule PERK inhibitors exhibit single agent efficacy against BrafV600E-dependent tumors highlighting the clinical value of targeting PERK. PMID:27977682

  9. PERK Is a Haploinsufficient Tumor Suppressor: Gene Dose Determines Tumor-Suppressive Versus Tumor Promoting Properties of PERK in Melanoma.

    PubMed

    Pytel, Dariusz; Gao, Yan; Mackiewicz, Katarzyna; Katlinskaya, Yuliya V; Staschke, Kirk A; Paredes, Maria C G; Yoshida, Akihiro; Qie, Shuo; Zhang, Gao; Chajewski, Olga S; Wu, Lawrence; Majsterek, Ireneusz; Herlyn, Meenhard; Fuchs, Serge Y; Diehl, J Alan

    2016-12-01

    The unfolded protein response (UPR) regulates cell fate following exposure of cells to endoplasmic reticulum stresses. PERK, a UPR protein kinase, regulates protein synthesis and while linked with cell survival, exhibits activities associated with both tumor progression and tumor suppression. For example, while cells lacking PERK are sensitive to UPR-dependent cell death, acute activation of PERK triggers both apoptosis and cell cycle arrest, which would be expected to contribute tumor suppressive activity. We have evaluated these activities in the BRAF-dependent melanoma and provide evidence revealing a complex role for PERK in melanoma where a 50% reduction is permissive for BrafV600E-dependent transformation, while complete inhibition is tumor suppressive. Consistently, PERK mutants identified in human melanoma are hypomorphic with dominant inhibitory function. Strikingly, we demonstrate that small molecule PERK inhibitors exhibit single agent efficacy against BrafV600E-dependent tumors highlighting the clinical value of targeting PERK.

  10. BRG1 and LKB1: tales of two tumor suppressor genes on chromosome 19p and lung cancer.

    PubMed

    Rodriguez-Nieto, Salvador; Sanchez-Cespedes, Montse

    2009-04-01

    Losses of heterozygosity (LOH) of the short arm of chromosome 19 are frequent in lung cancer, suggesting that one or more tumor suppressor genes are present in this region. The LKB1 gene, also called STK11, is somatically inactivated through point mutations and large deletions in lung tumors, demonstrating that LKB1 is a target of the LOH of this chromosomal arm. Data from several independent groups have provided information about the profiles of lung tumors with LKB1 inactivation and it is generally agreed that this alteration strongly predominates in non-small cell lung cancer, in particular adenocarcinomas, in smokers. The LKB1 protein has serine-threonine kinase activity and is involved in the regulation of the cell energetic checkpoint through the phosphorylation and activation of adenosine monophosphate-dependent kinase (AMPK). LKB1 is also involved in other processes such as cell polarization, probably through substrates other than AMPK. Interestingly, another gene on chromosome 19p, BRG1, encoding a component of the SWI/SNF chromatin-remodeling complex, has emerged as a tumor suppressor gene that is altered in lung tumors. Similar to LKB1, BRG1 is somatically inactivated by point mutations or large deletions in lung tumors featuring LOH of chromosome 19p. These observations suggest an important role for BRG1 in lung cancer and highlight the need to further our understanding of the function of Brahma/SWI2-related gene 1 (BRG1) in cancer. Finally, simultaneous mutations at LKB1 and BRG1 are common in lung cancer cells, which exemplifies how a single event, LOH of chromosome 19p in this instance, targets two different tumor suppressors.

  11. Tumor suppressor and deubiquitinase BAP1 promotes DNA double-strand break repair

    PubMed Central

    Yu, Helen; Pak, Helen; Hammond-Martel, Ian; Ghram, Mehdi; Rodrigue, Amélie; Daou, Salima; Barbour, Haithem; Corbeil, Luc; Hébert, Josée; Drobetsky, Elliot; Masson, Jean Yves; Di Noia, Javier M.; Affar, El Bachir

    2014-01-01

    The cellular response to highly genotoxic DNA double-strand breaks (DSBs) involves the exquisite coordination of multiple signaling and repair factors. Here, we conducted a functional RNAi screen and identified BAP1 as a deubiquitinase required for efficient assembly of the homologous recombination (HR) factors BRCA1 and RAD51 at ionizing radiation (IR) -induced foci. BAP1 is a chromatin-associated protein frequently inactivated in cancers of various tissues. To further investigate the role of BAP1 in DSB repair, we used a gene targeting approach to knockout (KO) this deubiquitinase in chicken DT40 cells. We show that BAP1-deficient cells are (i) sensitive to IR and other agents that induce DSBs, (ii) defective in HR-mediated immunoglobulin gene conversion, and (iii) exhibit an increased frequency of chromosomal breaks after IR treatment. We also show that BAP1 is recruited to chromatin in the proximity of a single site-specific I-SceI–induced DSB. Finally, we identified six IR-induced phosphorylation sites in BAP1 and showed that mutation of these residues inhibits BAP1 recruitment to DSB sites. We also found that both BAP1 catalytic activity and its phosphorylation are critical for promoting DNA repair and cellular recovery from DNA damage. Our data reveal an important role for BAP1 in DSB repair by HR, thereby providing a possible molecular basis for its tumor suppressor function. PMID:24347639

  12. The FHIT gene product: tumor suppressor and genome ‘caretaker’

    PubMed Central

    Waters, Catherine E.; Saldivar, Joshua C.; Hosseini, Seyed Ali; Huebner, Kay

    2014-01-01

    The FHIT gene at FRA3B is one of the earliest and most frequently altered genes in the majority of human cancers. It was recently discovered that the FHIT gene is not the most fragile locus in epithelial cells, the cell of origin for most Fhit negative cancers, eroding support for past claims that deletions at this locus are simply passenger events that are carried along in expanding cancer clones, due to extreme vulnerability to DNA damage rather than to loss of FHIT function. Indeed, recent reports have reconfirmed FHIT as a tumor suppressor gene with roles in apoptosis and prevention of the epithelial-mesenchymal transition. Other recent works have identified a novel role for the FHIT gene product, Fhit, as a genome ‘caretaker.’ Loss of this caretaker function leads to nucleotide imbalance, spontaneous replication stress, and DNA breaks. Because Fhit loss-induced DNA damage is “checkpoint blind,” cells accumulate further DNA damage during subsequent cell cycles, accruing global genome instability that could facilitate oncogenic mutation acquisition and expedite clonal expansion. Loss of Fhit activity therefore induces a mutator phenotype. Evidence for FHIT as a mutator gene is discussed in light of these recent investigations of Fhit loss and subsequent genome instability. PMID:25283145

  13. Characterizing WW domain interactions of tumor suppressor WWOX reveals its association with multiprotein networks.

    PubMed

    Abu-Odeh, Mohammad; Bar-Mag, Tomer; Huang, Haiming; Kim, TaeHyung; Salah, Zaidoun; Abdeen, Suhaib K; Sudol, Marius; Reichmann, Dana; Sidhu, Sachdev; Kim, Philip M; Aqeilan, Rami I

    2014-03-28

    WW domains are small modules present in regulatory and signaling proteins that mediate specific protein-protein interactions. The WW domain-containing oxidoreductase (WWOX) encodes a 46-kDa tumor suppressor that contains two N-terminal WW domains and a central short-chain dehydrogenase/reductase domain. Based on its ligand recognition motifs, the WW domain family is classified into four groups. The largest one, to which WWOX belongs, recognizes ligands with a PPXY motif. To pursue the functional properties of the WW domains of WWOX, we employed mass spectrometry and phage display experiments to identify putative WWOX-interacting partners. Our analysis revealed that the first WW (WW1) domain of WWOX is the main functional interacting domain. Furthermore, our study uncovered well known and new PPXY-WW1-interacting partners and shed light on novel LPXY-WW1-interacting partners of WWOX. Many of these proteins are components of multiprotein complexes involved in molecular processes, including transcription, RNA processing, tight junction, and metabolism. By utilizing GST pull-down and immunoprecipitation assays, we validated that WWOX is a substrate of the E3 ubiquitin ligase ITCH, which contains two LPXY motifs. We found that ITCH mediates Lys-63-linked polyubiquitination of WWOX, leading to its nuclear localization and increased cell death. Our data suggest that the WW1 domain of WWOX provides a versatile platform that links WWOX with individual proteins associated with physiologically important networks.

  14. Characterizing WW Domain Interactions of Tumor Suppressor WWOX Reveals Its Association with Multiprotein Networks*

    PubMed Central

    Abu-Odeh, Mohammad; Bar-Mag, Tomer; Huang, Haiming; Kim, TaeHyung; Salah, Zaidoun; Abdeen, Suhaib K.; Sudol, Marius; Reichmann, Dana; Sidhu, Sachdev; Kim, Philip M.; Aqeilan, Rami I.

    2014-01-01

    WW domains are small modules present in regulatory and signaling proteins that mediate specific protein-protein interactions. The WW domain-containing oxidoreductase (WWOX) encodes a 46-kDa tumor suppressor that contains two N-terminal WW domains and a central short-chain dehydrogenase/reductase domain. Based on its ligand recognition motifs, the WW domain family is classified into four groups. The largest one, to which WWOX belongs, recognizes ligands with a PPXY motif. To pursue the functional properties of the WW domains of WWOX, we employed mass spectrometry and phage display experiments to identify putative WWOX-interacting partners. Our analysis revealed that the first WW (WW1) domain of WWOX is the main functional interacting domain. Furthermore, our study uncovered well known and new PPXY-WW1-interacting partners and shed light on novel LPXY-WW1-interacting partners of WWOX. Many of these proteins are components of multiprotein complexes involved in molecular processes, including transcription, RNA processing, tight junction, and metabolism. By utilizing GST pull-down and immunoprecipitation assays, we validated that WWOX is a substrate of the E3 ubiquitin ligase ITCH, which contains two LPXY motifs. We found that ITCH mediates Lys-63-linked polyubiquitination of WWOX, leading to its nuclear localization and increased cell death. Our data suggest that the WW1 domain of WWOX provides a versatile platform that links WWOX with individual proteins associated with physiologically important networks. PMID:24550385

  15. Biophysical characterizations of human mitochondrial transcription factor A and its binding to tumor suppressor p53

    PubMed Central

    Wong, Tuck Seng; Rajagopalan, Sridharan; Freund, Stefan M.; Rutherford, Trevor J.; Andreeva, Antonina; Townsley, Fiona M.; Petrovich, Miriana; Fersht, Alan R.

    2009-01-01

    Human mitochondrial transcription factor A (TFAM) is a multi-functional protein, involved in different aspects of maintaining mitochondrial genome integrity. In this report, we characterized TFAM and its interaction with tumor suppressor p53 using various biophysical methods. DNA-free TFAM is a thermally unstable protein that is in equilibrium between monomers and dimers. Self-association of TFAM is modulated by its basic C-terminal tail. The DNA-binding ability of TFAM is mainly contributed by its first HMG-box, while the second HMG-box has low-DNA-binding capability. We also obtained backbone resonance assignments from the NMR spectra of both HMG-boxes of TFAM. TFAM binds primarily to the N-terminal transactivation domain of p53, with a Kd of 1.95 ± 0.19 μM. The C-terminal regulatory domain of p53 provides a secondary binding site for TFAM. The TFAM–p53-binding interface involves both TAD1 and TAD2 sub-domains of p53. Helices α1 and α2 of the HMG-box constitute the main p53-binding region. Since both TFAM and p53 binds preferentially to distorted DNA, the TFAM–p53 interaction is implicated in DNA damage and repair. In addition, the DNA-binding mechanism of TFAM and biological relevance of the TFAM–p53 interaction are discussed. PMID:19755502

  16. Key elements of the retinoblastoma tumor suppressor pathway in Volvox carteri.

    PubMed

    Hallmann, Armin

    2009-09-01

    The green alga Volvox carteri is one of the simplest multicellular organisms. It consists of only two cell types, somatic and reproductive cells, making it a suitable model system for studying cell division, multicellularity and cellular differentiation. Each of the approximately 2,000-4,000 cells of an adult, asexual organism arises through a sequence of symmetric and asymmetric cleavage divisions from a single, asexual reproductive cell. As in ontogenetic development of higher organisms, the fate of a Volvox blastomere (i.e., whether it undergoes division or differentiation) is determined by a complex balance of regulators. Retinoblastomarelated proteins (RBRs) seem to act as key regulators and hubs in cell cycle control and, therefore, have been investigated in detail in higher organisms. Recently, the identification and characterization of a gender-specific RBR in Volvox, RBR1, revealed a role for the retinoblastoma protein family in sexual development. RBRs are elements of a conserved signal-transduction pathway called the retinoblastoma (RB) tumor suppressor pathway. In addition to RBR1, other key components of this pathway are present in Volvox, demonstrating that the RB signal-transduction pathway is utilized by these simple green algae.

  17. Tumor suppressor protein C53 antagonizes checkpoint kinases to promote cyclin-dependent kinase 1 activation.

    PubMed

    Jiang, Hai; Wu, Jianchun; He, Chen; Yang, Wending; Li, Honglin

    2009-04-01

    Cyclin-dependent kinase 1 (Cdk1)/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 (also known as Cdk5rap3 and LZAP) potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. (2007) found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kappaB signaling. We report here the identification of C53 protein as a novel regulator of Cdk1 activation. We found that knockdown of C53 protein causes delayed Cdk1 activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 (Chk1 and Chk2) is partially inhibited by C53 overexpression. Intriguingly, we found that C53 interacts with Chk1 and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdk1 activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chk1, C53 promotes Cdk1 activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.

  18. Nuclear γ-tubulin associates with nucleoli and interacts with tumor suppressor protein C53.

    PubMed

    Hořejší, Barbora; Vinopal, Stanislav; Sládková, Vladimíra; Dráberová, Eduarda; Sulimenko, Vadym; Sulimenko, Tetyana; Vosecká, Věra; Philimonenko, Anatoly; Hozák, Pavel; Katsetos, Christos D; Dráber, Pavel

    2012-01-01

    γ-Tubulin is assumed to be a typical cytosolic protein necessary for nucleation of microtubules from microtubule organizing centers. Using immunolocalization and cell fractionation techniques in combination with siRNAi and expression of FLAG-tagged constructs, we have obtained evidence that γ-tubulin is also present in nucleoli of mammalian interphase cells of diverse cellular origins. Immunoelectron microscopy has revealed γ-tubulin localization outside fibrillar centers where transcription of ribosomal DNA takes place. γ-Tubulin was associated with nucleolar remnants after nuclear envelope breakdown and could be translocated to nucleoli during mitosis. Pretreatment of cells with leptomycin B did not affect the distribution of nuclear γ-tubulin, making it unlikely that rapid active transport via nuclear pores participates in the transport of γ-tubulin into the nucleus. This finding was confirmed by heterokaryon assay and time-lapse imaging of photoconvertible protein Dendra2 tagged to γ-tubulin. Immunoprecipitation from nuclear extracts combined with mass spectrometry revealed an association of γ-tubulin with tumor suppressor protein C53 located at multiple subcellular compartments including nucleoli. The notion of an interaction between γ-tubulin and C53 was corroborated by pull-down and co-immunoprecipitation experiments. Overexpression of γ-tubulin antagonized the inhibitory effect of C53 on DNA damage G(2) /M checkpoint activation. The combined results indicate that aside from its known role in microtubule nucleation, γ-tubulin may also have nuclear-specific function(s).

  19. Chemokine-enhanced chemotaxis of lymphangioleiomyomatosis cells with mutations in the tumor suppressor TSC2 gene.

    PubMed

    Pacheco-Rodriguez, Gustavo; Kumaki, Fumiyuki; Steagall, Wendy K; Zhang, Yi; Ikeda, Yoshihiko; Lin, Jing-Ping; Billings, Eric M; Moss, Joel

    2009-02-01

    Lymphangioleiomyomatosis (LAM) is characterized by cystic lung destruction caused by LAM cells (smooth-muscle-like cells) that have mutations in the tumor suppressor genes tuberous sclerosis complex (TSC) 1 or 2 and have the capacity to metastasize. Since chemokines and their receptors function in chemotaxis of metastatic cells, we hypothesized that LAM cells may be recruited by chemokine(s) in the lung. Quantification of 25 chemokines in bronchoalveolar lavage fluid from LAM patients and healthy volunteers revealed that concentrations of CCL2, CXCL1, and CXCL5 were significantly higher in samples from LAM patients than those from healthy volunteers. In vitro, CCL2 or MCP-1 induced selective migration of cells, showing loss of heterozygosity of TSC2 from a heterogeneous population of cells grown from explanted LAM lungs. Additionally, the frequencies of single-nucleotide polymorphisms in the CCL2 gene promoter region differed significantly in LAM patients and healthy volunteers (p = 0.018), and one polymorphism was associated significantly more frequently with the decline of lung function. The presence (i.e., potential functionality) of chemokine receptors was evaluated using immunohistochemistry in lung sections from 30 LAM patients. Expression of chemokines and these receptors varied among LAM patients and differed from that seen in some cancers (e.g., breast cancer and melanoma cells). These observations are consistent with the notion that chemokines such as CCL2 may serve to determine mobility and specify the site of metastasis of the LAM cell.

  20. Inactivation of tumor suppressor genes and cancer therapy: An evolutionary game theory approach.

    PubMed

    Khadem, Heydar; Kebriaei, Hamed; Veisi, Zahra

    2017-03-06

    Inactivation of alleles in tumor suppressor genes (TSG) is one of the important issues resulting in evolution of cancerous cells. In this paper, the evolution of healthy, one and two missed allele cells is modeled using the concept of evolutionary game theory and replicator dynamics. The proposed model also takes into account the interaction rates of the cells as designing parameters of the system. Different combinations of the equilibrium points of the parameterized nonlinear system is studied and categorized into some cases. In each case, the interaction rates' values are suggested in a way that the equilibrium points of the replicator dynamics are located on an appropriate region of the state space. Based on the suggested interaction rates, it is proved that the system doesn't have any undesirable interior equilibrium point as well. Therefore, the system will converge to the desirable region, where there is a scanty level of cancerous cells. In addition, the proposed conditions for interaction rates guarantee that, when a trajectory of the system reaches the boundaries, then it will stay there forever which is a desirable property since the equilibrium points have been already located on the boundaries, appropriately. The simulation results show the effectiveness of the suggestions in the elimination of the cancerous cells in different scenarios.

  1. Determinants of the tumor suppressor INPP4B protein and lipid phosphatase activities.

    PubMed

    Lopez, Sandra M; Hodgson, Myles C; Packianathan, Charles; Bingol-Ozakpinar, Ozlem; Uras, Fikriye; Rosen, Barry P; Agoulnik, Irina U

    2013-10-18

    The tumor suppressor INPP4B is an important regulator of phosphatidyl-inositol signaling in the cell. Reduced INPP4B expression is associated with poor outcomes for breast, prostate, and ovarian cancer patients. INPP4B contains a CX5R catalytic motif characteristic of dual-specificity phosphatases, such as PTEN. Lipid phosphatase activity of INPP4B has previously been described. In this report we show that INPP4B can dephosphorylate para-nitrophenyl phosphate (pNPP) and 6,8-difluoro-4-methylumbelliferyl (DiFMUP), synthetic phosphotyrosine analogs, suggesting that INPP4B has protein tyrosine phosphatase (PTP) activity. Using mutagenesis, we examined the functional role of specific amino acids within the INPP4B C842KSAKDR catalytic site. The K843M mutant displayed increased pNPP hydrolysis, the K846M mutant lost lipid phosphatase activity with no effect on PTP activity, and the D847E substitution ablated PTP activity and significantly reduced lipid phosphatase activity. Further, we show that INPP4B but not PTEN is able to reduce tyrosine phosphorylation of Akt1 and both the lipid and PTP activity of INPP4B likely contribute to the reduction of Akt1 phosphorylation. Taken together our data identified key residues in the INPP4B catalytic domain associated with lipid and protein phosphatase activities and found a robust downstream target regulated by INPP4B but not PTEN.

  2. Dual function of MDM2 and MDMX toward the tumor suppressors p53 and RB

    PubMed Central

    Hernández-Monge, Jesús; Rousset-Roman, Adriana Berenice; Medina-Medina, Ixaura; Olivares-Illana, Vanesa

    2016-01-01

    The orchestrated crosstalk between the retinoblastoma (RB) and p53 pathways contributes to preserving proper homeostasis within the cell. The deregulation of one or both pathways is a common factor in the development of most types of human cancer. The proto-oncoproteins MDMX and MDM2 are the main regulators of the well- known tumor suppressor p53 protein. Under normal conditions, MDM2 and MDMX inhibit p53, either via repression of its transcriptional activity by protein-protein interaction, or via polyubiquitination as a result of MDM2-E3 ubiquitin ligase activity, for which MDM2 needs to dimerize with MDMX. Under genotoxic stress conditions, both become positive regulators of p53. The ATM-dependent phosphorylation of MDM2 and MDMX allow them to bind p53 mRNA, these interactions promote p53 translation. MDM2 and MDMX are also being revealed as effective regulators of the RB protein. MDM2 is able to degrade RB by two different mechanisms, that is, by ubiquitin dependent and independent pathways. MDMX enhances the ability of MDM2 to bind and degrade RB protein. However, MDMX also seems to stabilize RB through interaction and competition with MDM2. Here, we will contextualize the findings that suggest that the MDM2 and MDMX proteins have a dual function on both p53 and RB. PMID:28050229

  3. Genistein mediated histone acetylation and demethylation activates tumor suppressor genes in prostate cancer cells.

    PubMed

    Kikuno, Nobuyuki; Shiina, Hiroaki; Urakami, Shinji; Kawamoto, Ken; Hirata, Hiroshi; Tanaka, Yuichiro; Majid, Shahana; Igawa, Mikio; Dahiya, Rajvir

    2008-08-01

    Genistein is a phytoestrogen that has been reported to suppress the AKT signaling pathway in several malignancies. However, the molecular mechanism of genistein action is not known. We tested the hypothesis that genistein activates expression of several aberrantly silenced tumor suppressor genes (TSGs) that have unmethylated promoters such as PTEN, CYLD, p53 and FOXO3a. We report here that genistein activates TSGs through remodeling of the heterochromatic domains at promoters in prostate cancer cells by modulating histone H3-Lysine 9 (H3-K9) methylation and deacetylation. Genistein activation involved demethylation and acetylation of H3-K9 at the PTEN and the CYLD promoter, while acetylation of H3-K9 at the p53 and the FOXO3a promoter occurred through reduction of endogenous SIRT1 activity. There was a decrease of SIRT1 expression and accumulation of SIRT1 in the cytoplasm from the nucleus. Increased expression of these TSGs was also reciprocally related to attenuation of phosphorylated-AKT and NF-kappaB binding activity in prostate cancer cells. This is the first report describing a novel epigenetic pathway that activates TSGs by modulating either histone H3-Lysine 9 (H3-K9) methylation or deacetylation at gene promoters leading to inhibition of the AKT signaling pathway. These findings strengthen the understanding of how genistein may be chemoprotective in prostate cancer.

  4. Downregulation of tumor suppressor QKI in gastric cancer and its implication in cancer prognosis

    SciTech Connect

    Bian, Yongqian; Wang, Li; Lu, Huanyu; Yang, Guodong; Zhang, Zhang; Fu, Haiyan; Lu, Xiaozhao; Wei, Mengying; Sun, Jianyong; Zhao, Qingchuan; Dong, Guanglong; Lu, Zifan

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer QKI expression is decreased in gastric cancer samples. Black-Right-Pointing-Pointer Promoter hyper methylation contributes to the downregulation of QKI. Black-Right-Pointing-Pointer QKI inhibits the growth of gastric cancer cells. Black-Right-Pointing-Pointer Decreased QKI expression predicts poor survival. -- Abstract: Gastric cancer (GC) is the fourth most common cancer and second leading cause of cancer-related death worldwide. RNA-binding protein Quaking (QKI) is a newly identified tumor suppressor in multiple cancers, while its role in GC is largely unknown. Our study here aimed to clarify the relationship between QKI expression with the clinicopathologic characteristics and the prognosis of GC. In the 222 GC patients' specimens, QKI expression was found to be significantly decreased in most of the GC tissues, which was largely due to promoter hypermethylation. QKI overexpression reduced the proliferation ability of GC cell line in vitro study. In addition, the reduced QKI expression correlated well with poor differentiation status, depth of invasion, gastric lymph node metastasis, distant metastasis, advanced TNM stage, and poor survival. Multivariate analysis showed QKI expression was an independent prognostic factor for patient survival.

  5. SUSD2 is frequently downregulated and functions as a tumor suppressor in RCC and lung cancer.

    PubMed

    Cheng, Yingying; Wang, Xiaolin; Wang, Pingzhang; Li, Ting; Hu, Fengzhan; Liu, Qiang; Yang, Fan; Wang, Jun; Xu, Tao; Han, Wenling

    2016-07-01

    Sushi domain containing 2 (SUSD2) is type I membrane protein containing domains inherent to adhesion molecules. There have been few reported studies on SUSD2, and they have mainly focused on breast cancer, colon cancer, and HeLa cells. However, the expression and function of SUSD2 in other cancers remain unclear. In the present study, we conducted an integrated bioinformatics analysis based on the array data from the GEO database and found a significant downregulation of SUSD2 in renal cell carcinoma (RCC) and lung cancer. Western blotting and quantitative RT-PCR (qRT-PCR) confirmed that SUSD2 was frequently decreased in RCC and lung cancer tissues compared with the corresponding levels in normal adjacent tissues. The restoration of SUSD2 expression inhibited the proliferation and clonogenicity of RCC and lung cancer cells, whereas the knockdown of SUSD2 promoted A549 cell growth. Our findings suggested that SUSD2 functions as a tumor suppressor gene (TSG) in RCC and lung cancer.

  6. Dual function of MDM2 and MDMX toward the tumor suppressors p53 and RB.

    PubMed

    Hernández-Monge, Jesús; Rousset-Roman, Adriana Berenice; Medina-Medina, Ixaura; Olivares-Illana, Vanesa

    2016-09-01

    The orchestrated crosstalk between the retinoblastoma (RB) and p53 pathways contributes to preserving proper homeostasis within the cell. The deregulation of one or both pathways is a common factor in the development of most types of human cancer. The proto-oncoproteins MDMX and MDM2 are the main regulators of the well- known tumor suppressor p53 protein. Under normal conditions, MDM2 and MDMX inhibit p53, either via repression of its transcriptional activity by protein-protein interaction, or via polyubiquitination as a result of MDM2-E3 ubiquitin ligase activity, for which MDM2 needs to dimerize with MDMX. Under genotoxic stress conditions, both become positive regulators of p53. The ATM-dependent phosphorylation of MDM2 and MDMX allow them to bind p53 mRNA, these interactions promote p53 translation. MDM2 and MDMX are also being revealed as effective regulators of the RB protein. MDM2 is able to degrade RB by two different mechanisms, that is, by ubiquitin dependent and independent pathways. MDMX enhances the ability of MDM2 to bind and degrade RB protein. However, MDMX also seems to stabilize RB through interaction and competition with MDM2. Here, we will contextualize the findings that suggest that the MDM2 and MDMX proteins have a dual function on both p53 and RB.

  7. Cyclin D activates the Rb tumor suppressor by mono-phosphorylation.

    PubMed

    Narasimha, Anil M; Kaulich, Manuel; Shapiro, Gary S; Choi, Yoon J; Sicinski, Piotr; Dowdy, Steven F

    2014-06-04

    The widely accepted model of G1 cell cycle progression proposes that cyclin D:Cdk4/6 inactivates the Rb tumor suppressor during early G1 phase by progressive multi-phosphorylation, termed hypo-phosphorylation, to release E2F transcription factors. However, this model remains unproven biochemically and the biologically active form(s) of Rb remains unknown. In this study, we find that Rb is exclusively mono-phosphorylated in early G1 phase by cyclin D:Cdk4/6. Mono-phosphorylated Rb is composed of 14 independent isoforms that are all targeted by the E1a oncoprotein, but show preferential E2F binding patterns. At the late G1 Restriction Point, cyclin E:Cdk2 inactivates Rb by quantum hyper-phosphorylation. Cells undergoing a DNA damage response activate cyclin D:Cdk4/6 to generate mono-phosphorylated Rb that regulates global transcription, whereas cells undergoing differentiation utilize un-phosphorylated Rb. These observations fundamentally change our understanding of G1 cell cycle progression and show that mono-phosphorylated Rb, generated by cyclin D:Cdk4/6, is the only Rb isoform in early G1 phase.

  8. Regulation of the activity of the tumor suppressor PTEN by thioredoxin in Drosophila melanogaster

    SciTech Connect

    Song, Zuohe; Saghafi, Negin; Gokhale, Vijay; Brabant, Marc; Meuillet, Emmanuelle J. . E-mail: emeuillet@azcc.arizona.edu

    2007-04-01

    Human Thioredoxin-1 (hTrx-1) is a small redox protein with a molecular weight of 12 kDa that contains two cysteine residues found in its catalytic site. HTrx-1 plays an important role in cell growth, apoptosis, and cancer patient prognosis. Recently, we have demonstrated that hTrx-1 binds to the C2 domain of the human tumor suppressor, PTEN, in a redox dependent manner. This binding leads to the inhibition of PTEN lipid phosphatase activity in mammalian tissue culture systems. In this study, we show that over-expression of hTrx-1 in Drosophila melanogaster promotes cell growth and proliferation during eye development as measured by eye size and ommatidia size. Furthermore, hTrx-1 rescues the small eye phenotype induced by the over-expression of PTEN. We demonstrate that this rescue of the PTEN-induced eye size phenotype requires cysteine-218 in the C2 domain of PTEN. We also show that hTrx-1 over-expression results in increased Akt phosphorylation in fly head extracts supporting our observations that the hTrx-1-induced eye size increase results from the inhibition of PTEN activity. Our study confirms the redox regulation of PTEN through disulfide bond formation with the hTrx-1 in Drosophila and suggests conserved mechanisms for thioredoxins and their interactions with the phosphatidylinositol-3-kinase signaling pathway in humans and fruit flies.

  9. Modulation of Cell Migration and Invasiveness by Tumor Suppressor TSC2 in Lymphangioleiomyomatosis

    PubMed Central

    Goncharova, Elena A.; Goncharov, Dmitriy A.; Lim, Poay N.; Noonan, Daniel; Krymskaya, Vera P.

    2006-01-01

    The loss of TSC2 function is associated with the pathobiology of lymphangioleiomyomatosis (LAM), which is characterized by the abnormal proliferation, migration, and differentiation of smooth muscle–like cells within the lungs. Although the etiology of LAM remains unknown, clinical and genetic evidence provides support for the neoplastic nature of LAM. The goal of this study was to determine the role of tumor suppressor TSC2 in the neoplastic potential of LAM cells. We show that primary cultures of human LAM cells exhibit increased migratory activity and invasiveness, which is abolished by TSC2 re-expression. We found that TSC2 also inhibits cell migration through its N-terminus, independent of its GTPase-activating protein activity. LAM cells show increased stress fiber and focal adhesion formation, which is attenuated by TSC2 re-expression. The small GTPase RhoA is activated in LAM cells compared with normal human mesenchymal cells. Pharmacologic inhibition of Rho activity abrogates LAM cell migration; RhoA activity was also abolished by TSC2 re-expression or TSC1 knockdown with specific siRNA. These data demonstrate that TSC2 controls cell migration through its N-terminus by associating with TSC1 and regulating RhoA activity, suggesting that TSC2 may play a critical role in modulating cell migration and invasiveness, which contributes to the pathobiology of LAM. PMID:16388022

  10. Simultaneous detection of the tumor suppressor FHIT gene and protein using the multi-functional biochip.

    PubMed

    Askari, Minoo D F; Miller, Gordon H; Vo-Dinh, Tuan

    2002-01-01

    The tumor suppressor gene, fragile histidine triad (FHIT), encompasses the most common human chromosomal fragile site, at 3pl4.2. Detection of FHIT gene is important in cancer diagnostics since its alterations have been associated with several human cancers. A unique multi-functional biochip for simultaneous detection of FHIT DNA and FHIT protein on the same platform was applied. The design of the biochip is based on miniaturization of photodiodes, where functioning of multiple optical sensing elements, amplifiers, discriminators, and logic circuitry are integrated on a single IC board. Performance of biochip is based on biomolecular recognition processes using both DNA and protein bioreceptors, Cy5-labeled probes and laser excitation. Application of biochip for concurrent detection of various immobilized target DNA and protein molecules and multiplex of DNA and protein on the same microarray was accomplished. Linearity of biochip for quantitative measurements was demonstrated. Results demonstrated utility of this multi-functional biochip as a useful detection technology with applications in biological and clinical laboratories.

  11. Interferon-Inducible Protein 16: Insight into the Interaction with Tumor Suppressor p53

    SciTech Connect

    Liao, Jack C.C.; Lam, Robert; Brazda, Vaclav; Duan, Shili; Ravichandran, Mani; Ma, Justin; Xiao, Ting; Tempel, Wolfram; Zuo, Xiaobing; Wang, Yun-Xing; Chirgadze, Nickolay Y.; Arrowsmith, Cheryl H.

    2011-08-24

    IFI16 is a member of the interferon-inducible HIN-200 family of nuclear proteins. It has been implicated in transcriptional regulation by modulating protein-protein interactions with p53 tumor suppressor protein and other transcription factors. However, the mechanisms of interaction remain unknown. Here, we report the crystal structures of both HIN-A and HIN-B domains of IFI16 determined at 2.0 and 2.35 {angstrom} resolution, respectively. Each HIN domain comprises a pair of tightly packed OB-fold subdomains that appear to act as a single unit. We show that both HIN domains of IFI16 are capable of enhancing p53-DNA complex formation and transcriptional activation via distinctive means. HIN-A domain binds to the basic C terminus of p53, whereas the HIN-B domain binds to the core DNA-binding region of p53. Both interactions are compatible with the DNA-bound state of p53 and together contribute to the effect of full-length IFI16 on p53-DNA complex formation and transcriptional activation.

  12. Structural insights into the functional versatility of WW domain-containing oxidoreductase tumor suppressor

    PubMed Central

    2015-01-01

    Recent work on WW domain-containing oxidoreductase (WWOX) tumor suppressor is beginning to shed new light on both the molecular mechanism of action of its WW domains as well as the contiguous catalytic domain. Herein, the structural basis underlying the ability of WW1 domain to bind to various physiological ligands and how the orphan WW2 tandem partner synergizes its ligand binding in the context of WW1–WW2 tandem module of WWOX is discussed. Notably, the WW domains within the WW1–WW2 tandem module physically associate so as to adopt a fixed spatial orientation relative to each other. In this manner, the association of WW2 domain with WW1 hinders ligand binding to the latter. Consequently, ligand binding to WW1 domain not only results in the displacement of WW2 lid but also disrupts the fixed orientation of WW domains in the liganded conformation. Equally importantly, structure-guided functional approach suggests that the catalytic domain of WWOX likely serves as a retinal oxidoreductase that catalyzes the reversible oxidation and reduction of all-trans-retinal. Collectively, this review provides structural insights into the functional versatility of a key signaling protein with important implications on its biology. PMID:25662954

  13. Structural insights into the functional versatility of WW domain-containing oxidoreductase tumor suppressor.

    PubMed

    Farooq, Amjad

    2015-03-01

    Recent work on WW domain-containing oxidoreductase (WWOX) tumor suppressor is beginning to shed new light on both the molecular mechanism of action of its WW domains as well as the contiguous catalytic domain. Herein, the structural basis underlying the ability of WW1 domain to bind to various physiological ligands and how the orphan WW2 tandem partner synergizes its ligand binding in the context of WW1-WW2 tandem module of WWOX is discussed. Notably, the WW domains within the WW1-WW2 tandem module physically associate so as to adopt a fixed spatial orientation relative to each other. In this manner, the association of WW2 domain with WW1 hinders ligand binding to the latter. Consequently, ligand binding to WW1 domain not only results in the displacement of WW2 lid but also disrupts the fixed orientation of WW domains in the liganded conformation. Equally importantly, structure-guided functional approach suggests that the catalytic domain of WWOX likely serves as a retinal oxidoreductase that catalyzes the reversible oxidation and reduction of all-trans-retinal. Collectively, this review provides structural insights into the functional versatility of a key signaling protein with important implications on its biology.

  14. Decreased Tumor Suppressor Candidate 3 Predicts Poor Prognosis of Patients with Esophageal Squamous Cell Carcinoma.

    PubMed

    Yu, Xinshuang; Zhang, Jiandong; Zhong, Hua; Liu, Fengjun; Liang, Ning; Wang, Yao; Meng, Xiangjiao; Du, Juan

    2016-01-01

    TUSC3 was recently identified as a potential tumor suppressor gene in a variety of human malignancies. However, no data are currently available regarding the expressions of TUSC3 in esophageal cancer (ESCC).The purposes of this study was to investigated the expressions of TUSC3 in ESCC tissues and assess the relationship between TUSC3 levels and clinico-pathological characteristics of ESCC patients. TUSC3 protein expressions were evaluated by immunohistochemistry (IHC) on tissue microarray slides in esophageal cancer, which included 95 esophageal squamous carcinoma specimens (ESCC), and 75 normal esophageal mucosa (NEM). We found that TUSC3 in ESCC was significant lower than that in NEM (P=0.000). According to multi-clinical classifications, TUSC3 level varied significantly with TNM stage, T stage, and N stage (p<0.001, p=0.0368, p<0.0001, respectively). Univariate analysis showed that gender, TNM stage, T stage, N stage, TUSC3 expression were prognostic factors for survival. Multivariate analysis showed that in our study, only TUSC3 expression was independent prognostic factors for ESCC. Our results indicated for the first time, a combined analysis of TUSC3 expressions as well as the clinical variables will help predict the prognosis of ESCC patients. Further large-sample validation and functional analysis should be performed to evaluate its potential prognostic and therapeutic values for ESCC patients.

  15. The SCFFBW7 ubiquitin ligase complex as a tumor suppressor in T cell leukemia.

    PubMed

    Thompson, Benjamin J; Buonamici, Silvia; Sulis, Maria Luisa; Palomero, Teresa; Vilimas, Tomas; Basso, Giuseppe; Ferrando, Adolfo; Aifantis, Iannis

    2007-08-06

    Recent studies have shown that activating mutations of NOTCH1 are responsible for the majority of T cell acute lymphoblastic leukemia (T-ALL) cases. Most of these mutations truncate its C-terminal domain, a region that is important for the NOTCH1 proteasome-mediated degradation. We report that the E3 ligase FBW7 targets NOTCH1 for ubiquitination and degradation. Our studies map in detail the amino acid degron sequence required for NOTCH1-FBW7 interaction. Furthermore, we identify inactivating FBW7 mutations in a large fraction of human T-ALL lines and primary leukemias. These mutations abrogate the binding of FBW7 not only to NOTCH1 but also to the two other characterized targets, c-Myc and cyclin E. The majority of the FBW7 mutations were present during relapse, and they were associated with NOTCH1 HD mutations. Interestingly, most of the T-ALL lines harboring FBW7 mutations were resistant to gamma-secretase inhibitor treatment and this resistance appeared to be related to the stabilization of the c-Myc protein. Our data suggest that FBW7 is a novel tumor suppressor in T cell leukemia, and implicate the loss of FBW7 function as a potential mechanism of drug resistance in T-ALL.

  16. Targeting Calcium Signaling Induces Epigenetic Reactivation of Tumor Suppressor Genes in Cancer.

    PubMed

    Raynal, Noël J-M; Lee, Justin T; Wang, Youjun; Beaudry, Annie; Madireddi, Priyanka; Garriga, Judith; Malouf, Gabriel G; Dumont, Sarah; Dettman, Elisha J; Gharibyan, Vazganush; Ahmed, Saira; Chung, Woonbok; Childers, Wayne E; Abou-Gharbia, Magid; Henry, Ryan A; Andrews, Andrew J; Jelinek, Jaroslav; Cui, Ying; Baylin, Stephen B; Gill, Donald L; Issa, Jean-Pierre J

    2016-03-15

    Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer.

  17. MYBL2 is a sub-haploinsufficient tumor suppressor gene in myeloid malignancy

    PubMed Central

    Heinrichs, Stefan; Conover, Lillian F; Bueso-Ramos, Carlos E; Kilpivaara, Outi; Stevenson, Kristen; Neuberg, Donna; Loh, Mignon L; Wu, Wen-Shu; Rodig, Scott J; Garcia-Manero, Guillermo; Kantarjian, Hagop M; Look, A Thomas

    2013-01-01

    A common deleted region (CDR) in both myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN) affects the long arm of chromosome 20 and has been predicted to harbor a tumor suppressor gene. Here we show that MYBL2, a gene within the 20q CDR, is expressed at sharply reduced levels in CD34+ cells from most MDS cases (65%; n = 26), whether or not they harbor 20q abnormalities. In a murine competitive reconstitution model, Mybl2 knockdown by RNAi to 20–30% of normal levels in multipotent hematopoietic progenitors resulted in clonal dominance of these ‘sub-haploinsufficient’ cells, which was reflected in all blood cell lineages. By 6 months post-transplantation, the reconstituted mice had developed a clonal myeloproliferative/myelodysplastic disorder originating from the cells with aberrantly reduced Mybl2 expression. We conclude that downregulation of MYBL2 activity below levels predicted by classical haploinsufficiency underlies the clonal expansion of hematopoietic progenitors in a large fraction of human myeloid malignancies. DOI: http://dx.doi.org/10.7554/eLife.00825.001 PMID:23878725

  18. Self-association of the WT1 tumor suppressor gene product

    SciTech Connect

    Bruening, W.; Nakagama, H.: Bardessy, N.

    1994-09-01

    Wilms` tumor (WT), an embryonal malignancy of the kidney, occurs most frequently in children under the age of 5 years, affecting {approximately}1 in 10,000 individuals. The WT1 tumor suppressor gene, residing at 11p13, is structurally altered in {approximately}10-15% of WT cases. Individuals with germline mutations within the WT1 gene suffer from predisposition to WT and developmental defects of the urogenital system. Patients with heterozygous deletions of the WT1 gene, or mutations predicted to cause inactivation of one WT1 allele, suffer relatively mild genital system defects (notably hypospadias and cryptorchidism in males) and a predisposition to WT. These results suggest that developing genital system development is sensitive to the absolute concentrations of the WT1 gene products. Patients with missense mutations within the WT1 gene, however, can suffer from a much more severe disorder known as Denys-Drash syndrome (DDS). This syndrome is characterized by intersex disorders, renal nephropathy, and a predisposition to WTs. The increased severity of the developmental defects associated with DDS, compared to those individuals with mild genital system anomalies and WTs, suggests that mutations defined in patients with DDS behave in a dominant-negative fashion. We have identified a novel WT1 mutation in a patient with DDS. This mutation, predicted to produce a truncated WT1 polypeptide encompassing exons 1, 2, and 3, defines a domain capable of behaving as an antimorph. We have also demonstrated that WT1 can self-associate in vivo using yeast two-hybrid systems. Deletion analysis have mapped the interacting domains to the amino terminus of the WT1 polypeptide, within exons 1 and 2. These results provide a molecular mechanism to explain how WT1 mutations can function in a dominant-negative fashion to eliminate wild-type WT1 activity, leading to DDS.

  19. BMP8B Is a Tumor Suppressor Gene Regulated by Histone Acetylation in Gastric Cancer.

    PubMed

    Wisnieski, Fernanda; Leal, Mariana Ferreira; Calcagno, Danielle Queiroz; Santos, Leonardo Caires; Gigek, Carolina Oliveira; Chen, Elizabeth Suchi; Artigiani, Ricardo; Demachki, Sâmia; Assumpção, Paulo Pimentel; Lourenço, Laércio Gomes; Burbano, Rommel Rodríguez; Smith, Marília Cardoso

    2017-04-01

    Different from genetic alterations, the reversible nature of epigenetic modifications provides an interesting opportunity for the development of clinically relevant therapeutics in different tumors. In this study, we aimed to screen and validate candidate genes regulated by the epigenetic marker associated with transcriptional activation, histone acetylation, in gastric cancer (GC). We first compared gene expression profile of trichostatin A-treated and control GC cell lines using microarray assay. Among the 55 differentially expressed genes identified in this analysis, we chose the up-regulated genes BMP8B and BAMBI for further analyses, that included mRNA and histone acetylation quantification in paired GC and nontumor tissue samples. BMP8B expression was reduced in GC compared to nontumor samples (P < 0.01). In addition, reduced BMP8B expression was associated with poorly differentiated GC (P = 0.02). No differences or histopathological associations were identified concerning BAMBI expression. Furthermore, acetylated H3K9 and H4K16 levels at BMP8B were increased in GC compared to nontumors (P < 0.05). However, reduced levels of acetylated H3K9 and H4K16 were associated with poorly differentiated GC (P < 0.05). Reduced levels of acetylated H3K9 was also associated with diffuse-type histological GC (P < 0.05). Notably, reduced BMP8B mRNA and acetylated H4K16 levels were positively correlated in poorly differentiated GC (P < 0.05). Our study demonstrated that BMP8B seems to be a tumor suppressor gene regulated by H4K16 acetylation in poorly differentiated GC. Therefore, BMP8B may be a potential target for TSA-based therapies in this GC sample subset. J. Cell. Biochem. 118: 869-877, 2017. © 2016 Wiley Periodicals, Inc.

  20. Tumor suppressor gene Rb is required for self-renewal of spermatogonial stem cells in mice.

    PubMed

    Hu, Yueh-Chiang; de Rooij, Dirk G; Page, David C

    2013-07-30

    The retinoblastoma tumor suppressor gene Rb is essential for maintaining the quiescence and for regulating the differentiation of somatic stem cells. Inactivation of Rb in somatic stem cells typically leads to their overexpansion, often followed by increased apoptosis, defective terminal differentiation, and tumor formation. However, Rb's roles in germ-line stem cells have not been explored. We conditionally disrupted the Rb gene in mouse germ cells in vivo and discovered unanticipated consequences for GFRa1-protein-expressing A(single) (GFRa1(+) A(s)) spermatogonia, the major source of male germ-line stem cells. Rb-deficient GFRa1(+) A(s) spermatogonia were present at normal density in testes 5 d after birth, but they lacked the capacity for self-renewal, resulting in germ cell depletion by 2 mo of age. Rb deficiency did not affect the proliferative activity of GFRa1(+) A(s) spermatogonia, but their progeny were exclusively transit-amplifying progenitor spermatogonia and did not include GFRa1(+) A(s) spermatogonia. In addition, Rb deficiency caused prolonged proliferation of progenitor spermatogonia, transiently enlarging this population. Despite these defects, Rb deficiency did not block terminal differentiation into functional sperm; offspring were readily obtained from young males whose germ cell pool was not yet depleted. We conclude that Rb is required for self-renewal of germ-line stem cells, but contrary to its critical roles in somatic stem cells, it is dispensable for their proliferative activity and terminal differentiation. Thus, this study identifies an unexpected function for Rb in maintaining the stem cell pool in the male germ line.

  1. Context-dependent activation of Wnt signaling by tumor suppressor RUNX3 in gastric cancer cells.

    PubMed

    Ju, Xiaoli; Ishikawa, Tomo-O; Naka, Kazuhito; Ito, Kosei; Ito, Yoshiaki; Oshima, Masanobu

    2014-04-01

    RUNX3 is a tumor suppressor for a variety of cancers. RUNX3 suppresses the canonical Wnt signaling pathway by binding to the TCF4/β-catenin complex, resulting in the inhibition of binding of the complex to the Wnt target gene promoter. Here, we confirmed that RUNX3 suppressed Wnt signaling activity in several gastric cancer cell lines; however, we found that RUNX3 increased the Wnt signaling activity in KatoIII and SNU668 gastric cancer cells. Notably, RUNX3 expression increased the ratio of the Wnt signaling-high population in the KatoIII cells. although the maximum Wnt activation level of individual cells was similar to that in the control. As found previously, RUNX3 also binds to TCF4 and β-catenin in KatoIII cells, suggesting that these molecules form a ternary complex. Moreover, the ChIP analyses revealed that TCF4, β-catenin and RUNX3 bind the promoter region of the Wnt target genes, Axin2 and c-Myc, and the occupancy of TCF4 and β-catenin in these promoter regions is increased by the RUNX3 expression. These results suggest that RUNX3 stabilizes the TCF4/β-catenin complex on the Wnt target gene promoter in KatoIII cells, leading to activation of Wnt signaling. Although RUNX3 increased the Wnt signaling activity, its expression resulted in suppression of tumorigenesis of KatoIII cells, indicating that RUNX3 plays a tumor-suppressing role in KatoIII cells through a Wnt-independent mechanism. These results indicate that RUNX3 can either suppress or activate the Wnt signaling pathway through its binding to the TCF4/β-catenin complex by cell context-dependent mechanisms.

  2. Functional interactions between Lmo2, the Arf tumor suppressor, and Notch1 in murine T-cell malignancies.

    PubMed

    Treanor, Louise M; Volanakis, Emmanuel J; Zhou, Sheng; Lu, Taihe; Sherr, Charles J; Sorrentino, Brian P

    2011-05-19

    LMO2 is a target of chromosomal translocations in T-cell tumors and was activated by retroviral vector insertions in T-cell tumors from X-SCID patients in gene therapy trials. To better understand the cooperating genetic events in LMO2-associated T-cell acute lymphoblastic leukemia (T-ALL), we investigated the roles of Arf tumor suppressor loss and Notch activation in murine models of transplantation. Lmo2 overexpression enhanced the expansion of primitive DN2 thymocytes, eventually facilitating the stochastic induction of clonal CD4(+)/CD8(+) malignancies. Inactivation of the Arf tumor suppressor further increased the self-renewal capacity of the primitive, preleukemic thymocyte pool and accelerated the development of aggressive, Lmo2-induced T-cell lympholeukemias. Notch mutations were frequently detected in these Lmo2-induced tumors. The Arf promoter was not directly engaged by Lmo2 or mutant Notch, and use of a mouse model in which activation of a mutant Notch allele depends on previous engagement of the Arf promoter revealed that Notch activation could occur as a subsequent event in T-cell tumorigenesis. Therefore, Lmo2 cooperates with Arf loss to enhance self-renewal in primitive thymocytes. Notch mutation and Arf inactivation appear to independently cooperate in no requisite order with Lmo2 overexpression in inducing T-ALL, and all 3 events remained insufficient to guarantee immediate tumor development.

  3. Loss of the tumor suppressor LKB1 promotes metabolic reprogramming of cancer cells via HIF-1α.

    PubMed

    Faubert, Brandon; Vincent, Emma E; Griss, Takla; Samborska, Bozena; Izreig, Said; Svensson, Robert U; Mamer, Orval A; Avizonis, Daina; Shackelford, David B; Shaw, Reuben J; Jones, Russell G

    2014-02-18

    One of the major metabolic changes associated with cellular transformation is enhanced nutrient utilization, which supports tumor progression by fueling both energy production and providing biosynthetic intermediates for growth. The liver kinase B1 (LKB1) is a serine/threonine kinase and tumor suppressor that couples bioenergetics to cell-growth control through regulation of mammalian target of rapamycin (mTOR) activity; however, the influence of LKB1 on tumor metabolism is not well defined. Here, we show that loss of LKB1 induces a progrowth metabolic program in proliferating cells. Cells lacking LKB1 display increased glucose and glutamine uptake and utilization, which support both cellular ATP levels and increased macromolecular biosynthesis. This LKB1-dependent reprogramming of cell metabolism is dependent on the hypoxia-inducible factor-1α (HIF-1α), which accumulates under normoxia in LKB1-deficient cells and is antagonized by inhibition of mTOR complex I signaling. Silencing HIF-1α reverses the metabolic advantages conferred by reduced LKB1 signaling and impairs the growth and survival of LKB1-deficient tumor cells under low-nutrient conditions. Together, our data implicate the tumor suppressor LKB1 as a central regulator of tumor metabolism and growth control through the regulation of HIF-1α-dependent metabolic reprogramming.

  4. PRKAR1A is a functional tumor suppressor inhibiting ERK/Snail/E-cadherin pathway in lung adenocarcinoma

    PubMed Central

    Wang, Shaoqiang; Cheng, Yuanda; Zheng, Yingying; He, Zhiwei; Chen, Wei; Zhou, Wolong; Duan, Chaojun; Zhang, Chunfang

    2016-01-01

    Protein Kinase cAMP-Dependent Regulatory Type I Alpha (PRKAR1A) is a tissue-specific extinguisher that transduces a signal through phosphorylation of different target proteins. Loss of PRKAR1A was frequently observed in endocrine neoplasia and stromal cell tumors. However, a few cases were seen in epithelial tumors. Previously, we first found that PRKAR1A was downregulated in lung adenocarcinoma patients. Thus, the present study aimed to clarify its clinical implication and biological function as a tumor suppressor in lung adenocarcinoma. The low levels of PRKAR1A transcript were correlated with tumor progression and poor overall survival. The re-expression of PRKAR1A in H1299 cells suppressed the tumor cell proliferation and migration; stable knockdown (KD) of PRKAR1A in A549 cells enhanced this function both in vitro and in vivo. Moreover, KD of PRKAR1A in A549 cells promoted the statistical colonization of circulating tumor cells to the lungs in nude mice. These effects by PRKAR1A were attributed to inhibiting E-cadherin expression. Elevated E-cadherin significantly suppressed the PRKAR1A-KD induced cell proliferation and migration. Most notably, deletion of PRKAR1A inhibited E-cadherin by activating ERK/Snail signaling. In conclusion, PRKAR1A was a potent suppressor, and through the inhibition of PRKAR1A-ERK-Snail-E-cadherin axis could serve as a potential therapeutic target. PMID:27995993

  5. The regulation of tumor suppressor protein, p53, and estrogen receptor (ERα) by resveratrol in breast cancer cells

    PubMed Central

    Saluzzo, Julieta; Hallman, Kelly M.; Aleck, Katie; Dwyer, Brigitte; Quigley, Meghan; Mladenovik, Viktoria; Siebert, Amy E.; Dinda, Sumi

    2016-01-01

    Resveratrol (RES) is a natural antioxidant found abundantly in grapes, peanuts, and berries, and is known to possess anti-tumorigenic properties. However, there is a noticeable lack of studies on the mechanistic effects of Resveratrol on tumor suppressors. Previous studies from our laboratory have shown the tumor suppressor protein p53 and estrogen receptor-alpha (ERα) to be possible molecular targets for RES. In this study, the anti-estrogenic effects of RES were analyzed on the expression of ERα and p53. The breast cancer cells grown in stripped serum were treated with 60 μM RES, as the optimum concentration based on data obtained from a concentration study using 1-100 μM RES. Our studies indicate that RES caused a decrease in the levels of protein expression of p53 and ERα as compared to the control. Increasing concentrations of RES caused a four-fold decrease in cell number in comparison to estradiol. RES, in conjunction with ICI 182,780 (ICI), caused a down-regulation of both p53 and ERα as compared to the control. These observed effects on cell proliferation and regulation of both p53 and ERα by RES may lead to further understanding of the relationship between tumor suppressor proteins and steroid receptors in breast cancer cells. PMID:28191286

  6. Candidate tumor suppressor LUCA-15/RBM5/H37 modulates expression of apoptosis and cell cycle genes

    SciTech Connect

    Mourtada-Maarabouni, Mirna . E-mail: bia19@biol.keele.ac.uk; Keen, Jennifer; Clark, Jeremy; Cooper, Colin S.; Williams, Gwyn T. . E-mail: g.t.williams@keele.ac.uk

    2006-06-10

    RBM5 (RNA-binding motif protein 5/LUCA-15/H37) is encoded at the lung cancer tumor suppressor locus 3p21.3 and itself has several important characteristics of a tumor suppressor, including both potentiation of apoptosis and inhibition of the cell cycle. Here, we report the effects of both upregulation and downregulation of LUCA-15/RBM5 on gene expression monitored using cDNA microarrays. Many of the genes modulated by LUCA-15/RBM5 are involved in the control of apoptosis, the cell cycle, or both. These effects were confirmed for the most significant genes using real-time RT-PCR and/or Western blotting. In particular, LUCA-15/RBM5 increased the expression of Stat5b and BMP5 and decreased the expression of AIB1 (Amplified In Breast Cancer 1), proto-oncogene Pim-1, caspase antagonist BIRC3 (cIAP-2, MIHC), and CDK2 (cyclin-dependent kinase 2). These effects on multiple genes controlling both apoptosis and proliferation are in line with the functional effects of LUCA-15/RBM5 and indicate that it plays a central role in regulating cell fate consistent with its tumor suppressor activity.

  7. TUSC4 functions as a tumor suppressor by regulating BRCA1's stability via the E3 ubiquitination pathway

    PubMed Central

    Peng, Yang; Dai, Hui; Wang, Edward; Lin, Curtis Chun-Jen; Mo, Wei; Peng, Guang; Lin, Shiaw-Yih

    2016-01-01

    Expression of the tumor suppressor protein BRCA1 is frequently lost in breast cancer patients, and the loss of its expression is associated with disruption of various critical functions in cells and cancer development. In the present study, we demonstrated that microarray analysis of cells with tumor suppressor candidate 4 (TUSC4) knockdown indicated critical changes such as cell cycle, cell death pathways and a global impact to cancer development. More importantly, we observed a clear cluster pattern of TUSC4-knockdown gene profiles with established homologous recombination (HR) repair defect signature. Additionally, TUSC4 protein can physically interact with E3 ligase Herc2 and prevents BRCA1 degradation via ubiquitination pathway. Knockdown of TUSC4 expression enhanced BRCA1 polyubiquitination, leading to BRCA1 protein degradation and a marked reduction in HR repair efficiency. Notably, ectopic expression of TUSC4 effectively suppressed the proliferation, invasion, and colony formation of breast cancer cells in vitro and tumorigenesis in vivo. Furthermore, knockdown of TUSC4 expression transformed normal mammary epithelial cells and enhanced the sensitivity of U2OS cells to the treatment of poly(ADP-ribose) polymerase inhibitors. Therefore, TUSC4 may act as a bona fide tumor suppressor by regulating BRCA1 protein stability and function in breast cancer. PMID:25480944

  8. A cooperative microRNA-tumor suppressor gene network in acute T-cell lymphoblastic leukemia (T-ALL)

    PubMed Central

    Mavrakis, Konstantinos J; Van Der Meulen, Joni; Wolfe, Andrew L; Liu, Xiaoping; Mets, Evelien; Taghon, Tom; Khan, Aly A; Setty, Manu; Rondou, Pieter; Vandenberghe, Peter; Delabesse, Eric; Benoit, Yves; Socci, Nicholas B; Leslie, Christina S; Van Vlierberghe, Pieter; Speleman, Frank; Wendel, Hans-Guido

    2014-01-01

    The importance of individual microRNAs (miRNAs) has been established in specific cancers. However, a comprehensive analysis of the contribution of miRNAs to the pathogenesis of any specific cancer is lacking. Here we show that in T-cell acute lymphoblastic leukemia (T-ALL), a small set of miRNAs is responsible for the cooperative suppression of several tumor suppressor genes. Cross-comparison of miRNA expression profiles in human T-ALL with the results of an unbiased miRNA library screen allowed us to identify five miRNAs (miR-19b, miR-20a, miR-26a, miR-92 and miR-223) that are capable of promoting T-ALL development in a mouse model and which account for the majority of miRNA expression in human T-ALL. Moreover, these miRNAs produce overlapping and cooperative effects on tumor suppressor genes implicated in the pathogenesis of T-ALL, including IKAROS (also known as IKZF1), PTEN, BIM, PHF6, NF1 and FBXW7. Thus, a comprehensive and unbiased analysis of miRNA action in T-ALL reveals a striking pattern of miRNA-tumor suppressor gene interactions in this cancer. PMID:21642990

  9. A novel proapoptotic gene PANO encodes a post-translational modulator of the tumor suppressor p14ARF

    SciTech Connect

    Watari, Akihiro; Li, Yang; Higashiyama, Shinji; Yutsudo, Masuo

    2012-02-01

    The protein p14ARF is a known tumor suppressor protein controlling cell proliferation and survival, which mainly localizes in nucleoli. However, the regulatory mechanisms that govern its activity or expression remain unclear. Here, we report that a novel proapoptotic nucleolar protein, PANO, modulates the expression and activity of p14ARF in HeLa cells. Overexpression of PANO enhances the stability of p14ARF protein by protecting it from degradation, resulting in an increase in p14ARF expression levels. Overexpression of PANO also induces apoptosis under low serum conditions. This effect is dependent on the nucleolar localization of PANO and inhibited by knocking-down p14ARF. Alternatively, PANO siRNA treated cells exhibit a reduction in p14ARF protein levels. In addition, ectopic expression of PANO suppresses the tumorigenicity of HeLa cells in nude mice. These results indicate that PANO is a new apoptosis-inducing gene by modulating the tumor suppressor protein, p14ARF, and may itself be a new candidate tumor suppressor gene.

  10. Breast cancer subtype dictates DNA methylation and ALDH1A3-mediated expression of tumor suppressor RARRES1

    PubMed Central

    Coyle, Krysta M.; Murphy, J. Patrick; Vidovic, Dejan; Vaghar-Kashani, Ahmad; Dean, Cheryl A.; Sultan, Mohammad; Clements, Derek; Wallace, Melissa; Thomas, Margaret L.; Hundert, Amos; Giacomantonio, Carman A.; Helyer, Lucy; Gujar, Shashi A.; Lee, Patrick W.K.; Weaver, Ian C.G.; Marcato, Paola

    2016-01-01

    Breast cancer subtyping, based on the expression of hormone receptors and other genes, can determine patient prognosis and potential options for targeted therapy. Among breast cancer subtypes, tumors of basal-like and claudin-low subtypes are typically associated with worse patient outcomes, are primarily classified as triple-negative breast cancers (TNBC), and cannot be treated with existing hormone-receptor-targeted therapies. Understanding the molecular basis of these subtypes will lead to the development of more effective treatment options for TNBC. In this study, we focus on retinoic acid receptor responder 1 (RARRES1) as a paradigm to determine if breast cancer subtype dictates protein function and gene expression regulation. Patient tumor dataset analysis and gene expression studies of a 26 cell-line panel, representing the five breast cancer subtypes, demonstrate that RARRES1 expression is greatest in basal-like TNBCs. Cell proliferation and tumor growth assays reveal that RARRES1 is a tumor suppressor in TNBC. Furthermore, gene expression studies, Illumina HumanMethylation450 arrays, and chromatin immunoprecipitation demonstrate that expression of RARRES1 is retained in basal-like breast cancers due to hypomethylation of the promoter. Additionally, expression of the cancer stem cell marker, aldehyde dehydrogenase 1A3, which provides the required ligand (retinoic acid) for RARRES1 transcription, is also specific to the basal-like subtype. We functionally demonstrate that the combination of promoter methylation and retinoic acid signaling dictates expression of tumor suppressor RARRES1 in a subtype-specific manner. These findings provide a precedent for a therapeutically-inducible tumor suppressor and suggest novel avenues of therapeutic intervention for patients with basal-like breast cancer. PMID:27286452

  11. Tumor suppressor NDRG2 inhibits glycolysis and glutaminolysis in colorectal cancer cells by repressing c-Myc expression.

    PubMed

    Xu, Xinyuan; Li, Jianying; Sun, Xiang; Guo, Yan; Chu, Dake; Wei, Li; Li, Xia; Yang, Guodong; Liu, Xinping; Yao, Libo; Zhang, Jian; Shen, Lan

    2015-09-22

    Cancer cells use glucose and glutamine as the major sources of energy and precursor intermediates, and enhanced glycolysis and glutamimolysis are the major hallmarks of metabolic reprogramming in cancer. Oncogene activation and tumor suppressor gene inactivation alter multiple intracellular signaling pathways that affect glycolysis and glutaminolysis. N-Myc downstream regulated gene 2 (NDRG2) is a tumor suppressor gene inhibiting cancer growth, metastasis and invasion. However, the role and molecular mechanism of NDRG2 in cancer metabolism remains unclear. In this study, we discovered the role of the tumor suppressor gene NDRG2 in aerobic glycolysis and glutaminolysis of cancer cells. NDRG2 inhibited glucose consumption and lactate production, glutamine consumption and glutamate production in colorectal cancer cells. Analysis of glucose transporters and the catalytic enzymes involved in glycolysis revealed that glucose transporter 1 (GLUT1), hexokinase 2 (HK2), pyruvate kinase M2 isoform (PKM2) and lactate dehydrogenase A (LDHA) was significantly suppressed by NDRG2. Analysis of glutamine transporter and the catalytic enzymes involved in glutaminolysis revealed that glutamine transporter ASC amino-acid transporter 2 (ASCT2) and glutaminase 1 (GLS1) was also significantly suppressed by NDRG2. Transcription factor c-Myc mediated inhibition of glycolysis and glutaminolysis by NDRG2. More importantly, NDRG2 inhibited the expression of c-Myc by suppressing the expression of β-catenin, which can transcriptionally activate C-MYC gene in nucleus. In addition, the growth and proliferation of colorectal cancer cells were suppressed significantly by NDRG2 through inhibition of glycolysis and glutaminolysis. Taken together, these findings indicate that NDRG2 functions as an essential regulator in glycolysis and glutaminolysis via repression of c-Myc, and acts as a suppressor of carcinogenesis through coordinately targeting glucose and glutamine transporter, multiple catalytic

  12. Ski is silenced by methylation and acts as tumor suppressor in non-small cell lung cancer.

    PubMed

    Xie, Mian; Wu, Xiaojun; He, Chaosheng; Zhang, Jiexia; Zhang, Jinjun

    2015-12-12

    Epigenetic silencing of tumor suppressors contributes to the development and progression of lung cancer. We recently found that Ski was hypermethylated in lung cancer. This study aimed to clarify its epigenetic alteration, molecular mechanisms and clinical significance in lung cancer. Ski methylation was evaluated by methylation-specific PCR (MS-PCR) and bisulfite sequencing. mRNA level of Ski was measured by RT-PCR and compared with the methylation status. Ski methylation correlated with decreased mRNA expression in human lung cancer cell lines. Ski hypermethylation was detected in 56.0% of primary lung tumors and associated with poor differentiation and late tumor stage. Demethylation agent 5-aza-2'-deoxycytidine (5-aza-2'dC) restored Ski expression. Re-expression of Ski in lung cancer cells inhibited cell proliferation, clonogenicity, migration, invasion and tumor formation. Ski decreased transcriptional activities of Smads and TAZ. Multivariate analysis showed that patients with Ski positive expression had a better overall survival in resected non-small cell lung cancer (NSCLC) patients. Our results revealed that Ski acts as a tumor suppressor inactivated by DNA methylation and is an independent prognostic factor of lung cancer.

  13. The RB tumor suppressor at the intersection of proliferation and immunity: relevance to disease immune evasion and immunotherapy.

    PubMed

    Hutcheson, Jack; Witkiewicz, Agnieszka K; Knudsen, Erik S

    2015-01-01

    The retinoblastoma tumor suppressor (RB) was the first identified tumor suppressor based on germline predisposition to the pediatric eye tumor. Since these early studies, it has become apparent that the functional inactivation of RB is a common event in nearly all human malignancy. A great deal of research has gone into understanding how the loss of RB promotes tumor etiology and progression. Since malignant tumors are characterized by aberrant cell division, much of this research has focused upon the ability of RB to regulate the cell cycle by repression of proliferation-related genes. However, it is progressively understood that RB is an important mediator of multiple functions. One area that is gaining progressive interest is the emerging role for RB in regulating diverse features of immune function. These findings suggest that RB is more than simply a regulator of cellular proliferation; it is at the crossroads of proliferation and the immune response. Here we review the data related to the functional roles of RB on the immune system, relevance to immune evasion, and potential significance to the response to immune-therapy.

  14. Immunohistochemical detection of p53 tumor-suppressor protein is a poor indicator of prognosis for canine cutaneous mast cell tumors.

    PubMed

    Ginn, P E; Fox, L E; Brower, J C; Gaskin, A; Kurzman, I D; Kubilis, P S

    2000-01-01

    Eighty-three canine cutaneous mast cell tumors were graded histologically and evaluated immunohistochemically for p53 tumor-suppressor protein expression. An avidin-biotin immunohistochemical protocol incorporated a rabbit polyclonal antibody (CM-1) directed against normal and mutant p53 protein. Positive staining was observed in 44.6% (37/83) of tumors and included 50% (12/24) of grade I (well differentiated) tumors, 46.9% (23/49) of grade II (intermediate differentiation) tumors, and 20% (2/10) of grade III (poorly differentiated) tumors. A statistically significantly higher proportion (P < 0.019) of tumors from the head and neck (83.3%, 10/12), stained positive for p53 than tumors from the thorax, back, abdomen, and axilla (39.4%, 13/33), legs (35.7%, 10/28), or prepuce, scrotal, or inguinal areas (44.4%, 4/9). No statistically significant difference between p53 labeling and histologic grade, breed, or tumor size was present. Survival data were available for 53/83 (63.9%) of dogs. Positive reactivity for p53 was observed in 47% (25/53) of tumors within this group, with 57.9% (11/19) of grade I, 43.3% (13/30) of grade II, and 25% (1/4) of grade III tumors labeled. Mean survival time for the 53 dogs was 12.1 months. The median survival time for dogs with grade III tumors or tumors >5 cm was statistically significantly shorter (P < 0.0001) than for dogs with grades I and II or smaller tumors. Although p53 protein abnormalities may play a role in tumor development or behavior in some canine cutaneous mast cell tumors, immunoreactivity was not associated with lack of tumor differentiation, tumor locations previously shown to demonstrate aggressive biological behavior, breed predisposition, or survival times.

  15. Driver gene classification reveals a substantial overrepresentation of tumor suppressors among very large chromatin-regulating proteins

    PubMed Central

    Waks, Zeev; Weissbrod, Omer; Carmeli, Boaz; Norel, Raquel; Utro, Filippo; Goldschmidt, Yaara

    2016-01-01

    Compiling a comprehensive list of cancer driver genes is imperative for oncology diagnostics and drug development. While driver genes are typically discovered by analysis of tumor genomes, infrequently mutated driver genes often evade detection due to limited sample sizes. Here, we address sample size limitations by integrating tumor genomics data with a wide spectrum of gene-specific properties to search for rare drivers, functionally classify them, and detect features characteristic of driver genes. We show that our approach, CAnceR geNe similarity-based Annotator and Finder (CARNAF), enables detection of potentially novel drivers that eluded over a dozen pan-cancer/multi-tumor type studies. In particular, feature analysis reveals a highly concentrated pool of known and putative tumor suppressors among the <1% of genes that encode very large, chromatin-regulating proteins. Thus, our study highlights the need for deeper characterization of very large, epigenetic regulators in the context of cancer causality. PMID:28008934

  16. Driver gene classification reveals a substantial overrepresentation of tumor suppressors among very large chromatin-regulating proteins.

    PubMed

    Waks, Zeev; Weissbrod, Omer; Carmeli, Boaz; Norel, Raquel; Utro, Filippo; Goldschmidt, Yaara

    2016-12-23

    Compiling a comprehensive list of cancer driver genes is imperative for oncology diagnostics and drug development. While driver genes are typically discovered by analysis of tumor genomes, infrequently mutated driver genes often evade detection due to limited sample sizes. Here, we address sample size limitations by integrating tumor genomics data with a wide spectrum of gene-specific properties to search for rare drivers, functionally classify them, and detect features characteristic of driver genes. We show that our approach, CAnceR geNe similarity-based Annotator and Finder (CARNAF), enables detection of potentially novel drivers that eluded over a dozen pan-cancer/multi-tumor type studies. In particular, feature analysis reveals a highly concentrated pool of known and putative tumor suppressors among the <1% of genes that encode very large, chromatin-regulating proteins. Thus, our study highlights the need for deeper characterization of very large, epigenetic regulators in the context of cancer causality.

  17. Allostery Mediates Ligand Binding to WWOX Tumor Suppressor via a Conformational Switch

    PubMed Central

    Schuchardt, Brett J.; Mikles, David C.; Bhat, Vikas; McDonald, Caleb B.; Sudol, Marius; Farooq, Amjad

    2014-01-01

    While being devoid of the ability to recognize ligands itself, the WW2 domain is believed to aid ligand binding to WW1 domain in the context of WW1-WW2 tandem module of WWOX tumor suppressor. In an effort to test the generality of this hypothesis, we have undertaken here a detailed biophysical analysis of the binding of WW domains of WWOX alone and in the context of WW1-WW2 tandem module to an array of putative PPXY ligands. Our data show that while the WW1 domain of WWOX binds to all ligands in a physiologically-relevant manner, the WW2 domain does not. Moreover, ligand binding to WW1 domain in the context of WW1-WW2 tandem module is two-to-three-fold stronger than when treated alone. We also provide evidence that the WW domains within the WW1-WW2 tandem module physically associate so as to adopt a fixed spatial orientation relative to each other. Of particular note is the observation that the physical association of WW2 domain with WW1 blocks access to ligand. Consequently, ligand binding to WW1 domain not only results in the displacement of WW2 lid but also disrupts the physical association of WW domains in the liganded conformation. Taken together, our study underscores a key role of allosteric communication in the ability of WW2 orphan domain to chaperone physiological action of WW1 domain within the context of the WW1-WW2 tandem module of WWOX. PMID:25703206

  18. Biophysical basis of the binding of WWOX tumor suppressor to WBP1 and WBP2 adaptors.

    PubMed

    McDonald, Caleb B; Buffa, Laura; Bar-Mag, Tomer; Salah, Zaidoun; Bhat, Vikas; Mikles, David C; Deegan, Brian J; Seldeen, Kenneth L; Malhotra, Arun; Sudol, Marius; Aqeilan, Rami I; Nawaz, Zafar; Farooq, Amjad

    2012-09-07

    The WW-containing oxidoreductase (WWOX) tumor suppressor participates in a diverse array of cellular activities by virtue of its ability to recognize WW-binding protein 1 (WBP1) and WW-binding protein 2 (WBP2) signaling adaptors among a wide variety of other ligands. Herein, using a multitude of biophysical techniques, we provide evidence that while the WW1 domain of WWOX binds to PPXY motifs within WBP1 and WBP2 in a physiologically relevant manner, the WW2 domain exhibits no affinity toward any of these PPXY motifs. Importantly, our data suggest that while R25/W44 residues located within the binding pocket of a triple-stranded β-fold of WW1 domain are critical for the recognition of PPXY ligands, they are replaced by the chemically distinct E66/Y85 duo at structurally equivalent positions within the WW2 domain, thereby accounting for its failure to bind PPXY ligands. Predictably, not only does the introduction of E66R/Y85W double substitution within the WW2 domain result in gain of function but the resulting engineered domain, hereinafter referred to as WW2_RW, also appears to be a much stronger binding partner of WBP1 and WBP2 than the wild-type WW1 domain. We also show that while the WW1 domain is structurally disordered and folds upon ligand binding, the WW2 domain not only adopts a fully structured conformation but also aids stabilization and ligand binding to WW1 domain. This salient observation implies that the WW2 domain likely serves as a chaperone to augment the physiological function of WW1 domain within WWOX. Collectively, our study lays the groundwork for understanding the molecular basis of a key protein-protein interaction pertinent to human health and disease.

  19. Biophysical Basis of the Binding of WWOX Tumor Suppressor to WBP1 and WBP2 Adaptors

    PubMed Central

    McDonald, Caleb B.; Buffa, Laura; Bar-Mag, Tomer; Salah, Zaidoun; Bhat, Vikas; Mikles, David C.; Deegan, Brian J.; Seldeen, Kenneth L.; Malhotra, Arun; Sudol, Marius; Aqeilan, Rami I.; Nawaz, Zafar; Farooq, Amjad

    2012-01-01

    The WWOX tumor suppressor participates in a diverse array of cellular activities by virtue of its ability to recognize WBP1 and WBP2 signaling adaptors among a wide variety of other ligands. Herein, using a multitude of biophysical techniques, we provide evidence that while the WW1 domain of WWOX binds to PPXY motifs within WBP1 and WBP2 in a physiologically-relevant manner, the WW2 domain exhibits no affinity toward any of these PPXY motifs. Importantly, our data suggest that while R25/W44 residues located within the binding pocket of triple-stranded β-fold of WW1 domain are critical for the recognition of PPXY ligands, they are replaced by the chemically-distinct E66/Y85 duo at structurally-equivalent positions within the WW2 domain, thereby accounting for its failure to bind PPXY ligands. Predictably, introduction of E66R/Y85W double-substitution within the WW2 domain not only results in gain-of-function but the resulting engineered domain, hereinafter referred to as WW2_RW, also appears to be a much stronger binding partner of WBP1 and WBP2 than the wild type WW1 domain. We also show that while the WW1 domain is structurally disordered and folds upon ligand binding, the WW2 domain not only adopts a fully structured conformation but also aids stabilization and ligand binding to WW1 domain. This salient observation implies that the WW2 domain likely serves as a chaperone to augment the physiological function of WW1 domain within WWOX. Collectively, our study lays the groundwork for understanding the molecular basis of a key protein-protein interaction pertinent to human health and disease. PMID:22634283

  20. BAX and tumor suppressor TRP53 are important in regulating mutagenesis in spermatogenic cells in mice.

    PubMed

    Xu, Guogang; Vogel, Kristine S; McMahan, C Alex; Herbert, Damon C; Walter, Christi A

    2010-12-01

    During the first wave of spermatogenesis, and in response to ionizing radiation, elevated mutant frequencies are reduced to a low level by unidentified mechanisms. Apoptosis is occurring in the same time frame that the mutant frequency declines. We examined the role of apoptosis in regulating mutant frequency during spermatogenesis. Apoptosis and mutant frequencies were determined in spermatogenic cells obtained from Bax-null or Trp53-null mice. The results showed that spermatogenic lineage apoptosis was markedly decreased in Bax-null mice and was accompanied by a significantly increased spontaneous mutant frequency in seminiferous tubule cells compared to that of wild-type mice. Apoptosis profiles in the seminiferous tubules for Trp53-null were similar to control mice. Spontaneous mutant frequencies in pachytene spermatocytes and in round spermatids from Trp53-null mice were not significantly different from those of wild-type mice. However, epididymal spermatozoa from Trp53-null mice displayed a greater spontaneous mutant frequency compared to that from wild-type mice. A greater proportion of spontaneous transversions and a greater proportion of insertions/deletions 15 days after ionizing radiation were observed in Trp53-null mice compared to wild-type mice. Base excision repair activity in mixed germ cell nuclear extracts prepared from Trp53-null mice was significantly lower than that for wild-type controls. These data indicate that BAX-mediated apoptosis plays a significant role in regulating spontaneous mutagenesis in seminiferous tubule cells obtained from neonatal mice, whereas tumor suppressor TRP53 plays a significant role in regulating spontaneous mutagenesis between postmeiotic round spermatid and epididymal spermatozoon stages of spermiogenesis.

  1. A neurodegenerative disease affecting synaptic connections in Drosophila mutant for the tumor suppressor morphogen Patched

    PubMed Central

    Gazi, Michal; Shyamala, Baragur V.; Bhat, Krishna Moorthi

    2009-01-01

    The tumor-suppressor morphogen, Patched (Ptc), has extensive homology to the Niemann-Pick-C 1 (NPC1) protein. The NPC disease is a paediatric, progressive and fatal neurodegenerative disorder thought to be due to an abnormal accumulation of cholesterol in neurons. Here, we report that patched mutant adults develop a progressive neurodegenerative disease and their brain contains membranous and lamellar inclusions. There is also a significant reduction in the number of synaptic terminals in the brain of the mutant adults. Interestingly, feeding cholesterol to wild type flies generates inclusions in the brain, but does not cause the disease. However, feeding cholesterol to mutant flies increases synaptic connections and suppresses the disease. Our results suggest that sequestration of cholesterol in the mutant brain in the form of membranous material and inclusions affects available pool of cholesterol for cellular functions. This, in turn, negatively affects the synaptic number and contributes to the disease-state. Consistent with this, in ptc mutants there is a reduction in the pool of cholesterol esters, and cholesterol-mediated suppression of the disease accompanies an increase in cholesterol esters. We further show that Ptc does not function directly in this process since gain-of-function for Hedgehog also induces the same disease with a reduction in the level of cholesterol esters. We believe that loss of function for ptc causes neurodegeneration via two distinct ways: de-repression of genes that interfere with lipid trafficking, and de-repression of genes outside of the lipid trafficking; the functions of both classes of genes ultimately converge on synaptic connections. PMID:19635474

  2. The tumor suppressor PTEN regulates motor responses to striatal dopamine in normal and Parkinsonian animals.

    PubMed

    Stavarache, Mihaela A; Musatov, Sergei; McGill, Marlon; Vernov, Mary; Kaplitt, Michael G

    2015-10-01

    Phosphatase and Tensin homolog deleted on chromosome 10 (PTEN) is a dual lipid-protein phosphatase known primarily as a growth preventing tumor suppressor. PTEN is also expressed in neurons, and pathways modulated by PTEN can influence neuronal function. Here we report a novel function of PTEN as a regulator of striatal dopamine signaling in a model of Parkinson's disease (PD). Blocking PTEN expression with an adeno-associated virus (AAV) vector expressing a small hairpin RNA (shRNA) resulted in reduced responses of cultured striatal neurons to dopamine, which appeared to be largely due to reduction in D2 receptor activation. Co-expression of shRNA-resistant wild-type and mutant forms of PTEN indicated that the lipid-phosphatase activity was essential for this effect. In both normal and Parkinsonian rats, inhibition of striatal PTEN in vivo resulted in motor dysfunction and impaired responses to dopamine, particularly D2 receptor agonists. Expression of PTEN mutants confirmed the lipid-phosphatase activity as critical, while co-expression of a dominant-negative form of Akt overcame the PTEN shRNA effect. These results identify PTEN as a key mediator of striatal responses to dopamine, and suggest that drugs designed to potentiate PTEN expression or activity, such as cancer chemotherapeutics, may also be useful for improving striatal responses to dopamine in conditions of dopamine depletion such as PD. This also suggests that strategies which increase Akt or decrease PTEN expression or function, such as growth factors to prevent neuronal death, may have a paradoxical effect on neurological functioning by inhibiting striatal responses to dopamine.

  3. Tumor suppressor gene P53 in fish species as a target for genotoxic effects monitoring

    SciTech Connect

    Kusser, W.C.; Brand, D.; Glickman, B.W.; Cretney, W.

    1995-12-31

    Analysis of environmentally induced molecular changes in DNA from fish was initiated with a study of tumor suppressor gene p53. This gene was chosen because of the high number of documented mutations in p53 from humans and their relevance in tumorigenesis. Bottom-feeding flatfish (e.g. English sole, Pleuronectes vetulus) and members of the salmonid family (e.g. rainbow trout, Oncorhynchus mykiss and chinook salmon, O. tschaaytsha) were chosen, because they are widespread and of commercial and recreational importance. The studies include the use of histopathological, biochemical, and molecular genetic tools in aquatic systems. The authors are currently examining the deposition of DNA damage and mutation in the p53 gene in fish. Parallel histopathology of liver showed idiopathic liver lesions that were strongly dependent on location of capture (0.01 < p(X{sup 2} 0.05, 2 > 6.89) < 0.025) with a prevalence of 30% for fish collected from the vicinity of pulp mills. To assess DNA damage and mutation analysis, DNA was extracted from fish liver. Polymerase chain reaction (PCR) and DNA sequencing of the p53 gene was performed for rainbow trout, chinook and sockeye salmon, O. nerka. Southern blotting with a labeled p53 probe from rainbow trout was performed using genomic DNA from various teleost fish species. The presence of p53 could be shown in all fish species examined, including salmonids and sentinel species for environmental monitoring like English sole and white sucker (Catostomus commersom). To correlate histopathology with molecular analysis the authors initiated the determination of DNA damage, DNA adducts and mutations in the p53 gene (conserved exons 5 to 9).

  4. Structural Studies of the SET Domain from RIZ1 Tumor Suppressor

    SciTech Connect

    Briknarova, Klara; Zhou, Xinliang; Satterthwait, Arnold C.; Hoyt, David W.; Ely, Kathryn R.; Huang, Shi

    2008-02-15

    Histone lysine methyltransferases (HKMTs) are involved in regulation of chromatin structure, and, as such, are important for longterm gene activation and repression that is associated with cell memory and establishment of cell-type specific transcriptional programs. Most HKMTs contain a SET domain, which is responsible for their catalytic activity. RIZ1 is a transcription regulator and tumor suppressor that catalyzes methylation of lysine 9 of histone H3 and contains a rather distinct SET domain. Similar SET domains, sometimes refererred to as PR (PRDI-BF1 and RIZ1 homology) domains, are also found in other proteins including Blimp-1/PRDI-BF1, MDS1-EVI1 and Meisetz. We determined the solution structure of the PR domain from RIZ1 and characterized its interaction with S-adenosyl homocysteine (SAH) and a peptide from histone H3. Despite low sequence identity with canonical SET domains, the PR domain displays a typical SET fold including a pseudo-knot at the C-terminus. The N-flanking sequence of RIZ1 PR domain adopts a novel conformation and interacts closely with the SET fold. The C-flanking sequence contains an α-helix that exhibits higher mobility than the SET fold and points away from the protein face that harbors active site in other SET domains. Residues that interact with the methylation cofactor in SET domains are not conserved in RIZ1 or other PR domains, and the SET fold of RIZ1 does not bind SAH. However, the PR domain of RIZ1 interacts specifically with a synthetic peptide comprising residues 1-20 of histone H3.

  5. Peptide Conformations for a Microarray Surface-Tethered Epitope of the Tumor Suppressor p53

    SciTech Connect

    Feng, Jun; Wong, Ka-Yiu; Lynch, Gillian C.; Gao, Xiaolian; Pettitt, Bernard M.

    2007-12-13

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Peptides or proteins near surfaces exhibit different structural properties from those present in a homogeneous solution, and these differences give rise to varied biological activity. Therefore, understanding the detailed molecular structure of these molecules tethered to a surface is important for interpreting the performance of the various microarrays based on the activities of the immobilized peptides or proteins. We performed molecular dynamics simulations of a pentapeptide, RHSVV, an epitope of the tumor suppressor protein p53, tethered via a spacer on a functionalized silica surface and free in solution, to study their structural and conformational differences. These calculations allowed analyses of the peptide-surface interactions, the sequence orientations, and the translational motions of the peptide on the surface to be performed. Conformational similarities are found among dominant structures of the tethered and free peptide. In the peptide microarray simulations, the peptide fluctuates between a parallel and tilted orientation driven in part by the hydrophobic interactions between the nonpolar peptide residues and the methyl-terminated silica surface. The perpendicular movement of the peptide relative to the surface is also restricted due to the hydrophobic nature of the microarray surface. With regard to structures available for recognition and binding, we find that similar conformations to those found in solution are available to the peptide tethered to the surface, but with a shifted equilibrium constant. Comparisons with experimental results show important implications of this for peptide microarray design and assays.

  6. The tumor suppressor Lgl1 regulates front-rear polarity of migrating cells.

    PubMed

    Ravid, Shoshana

    2014-01-01

    Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally. The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division. But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro. Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration. We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization. Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments. We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells.

  7. MTUS1 tumor suppressor and its miRNA regulators in fibroadenoma and breast cancer.

    PubMed

    Kara, Murat; Kaplan, Mehmet; Bozgeyik, Ibrahim; Ozcan, Onder; Celik, Ozgur Ilhan; Bozgeyik, Esra; Yumrutas, Onder

    2016-08-10

    Breast cancer is major public health problem predominantly effects female population. Current therapeutic approaches to deal with breast cancer are still lack of effectiveness. Thus, identifying/developing novel strategies to fight against breast cancer is very important. The frequent deletions at 8p21.3-22 chromosomal location nearby D8S254 marker enabled the discovery of a novel tumor suppressor gene, MTUS1. Subsequently, MTUS1 was demonstrated to be less expressed in a variety cancer types including breast cancer. Also, it is obvious that gene expression is widely regulated by miRNAs. Here, we aimed to report differential expression of MTUS1 and its regulatory miRNAs in breast cancer and fibroadenoma tissues. Dynamic analysis of MTUS1 expression levels and its miRNAs regulators were attained by Fluidigm 96×96 Dynamic Array Expression chips and reactions were performed in Fluidigm BioMark™ HD System qPCR. Consequently, MTUS1 mRNA levels were significantly diminished in breast cancer tissues and elevated in fibroadenoma tissues. Also, among MTUS1 targeting miRNAs, miR-183-5p was identified to be overexpressed in breast cancer and down-regulated in fibroadenoma tissues. Also, expression levels of MTUS1 and miR-183-5p were well correlated with clinical parameters. In particular, MTUS1 expression was found to be diminished and miR-183-5p expression was elevated with the advancing stage. In conclusion, as a potential therapeutic target, miR-183-5p can be a chief regulator of MTUS1 and MTUS1-miR-183-5p axis may have significant influence in the pathology of breast cancer.

  8. SUMOylation of the ING1b tumor suppressor regulates gene transcription

    PubMed Central

    Satpathy, Shankha; Guérillon, Claire; Kim, Tae-Sun; Bigot, Nicolas; Thakur, Satbir; Bonni, Shirin; Riabowol, Karl; Pedeux, Rémy

    2014-01-01

    The INhibitor of Growth (ING) proteins are encoded as multiple isoforms in five ING genes (ING1 –5) and act as type II tumor suppressors. They are growth inhibitory when overexpressed and are frequently mislocalized or downregulated in several forms of cancer. ING1 and ING2 are stoichiometric members of histone deacetylase complexes, whereas ING3–5 are stoichiometric components of different histone acetyltransferase complexes. The INGs target these complexes to histone marks, thus acting as epigenetic regulators. ING proteins affect angiogenesis, apoptosis, DNA repair, metastasis and senescence, but how the proteins themselves are regulated is not yet clear. Here, we find a small ubiquitin-like modification (SUMOylation) of the ING1b protein and identify lysine 193 (K193) as the preferred ING1b SUMO acceptor site. We also show that PIAS4 is the E3 SUMO ligase responsible for ING1b SUMOylation on K193. Sequence alignment reveals that the SUMO consensus site on ING1b contains a phosphorylation-dependent SUMOylation motif (PDSM) and our data indicate that the SUMOylation on K193 is enhanced by the S199D phosphomimic mutant. Using an ING1b protein mutated at the major SUMOylation site (ING1b E195A), we further demonstrate that ING1b SUMOylation regulates the binding of ING1b to the ISG15 and DGCR8 promoters, consequently regulating ISG15 and DGCR8 transcription. These results suggest a role for ING1b SUMOylation in the regulation of gene transcription. PMID:24903338

  9. Repression of estrogen receptor {beta} function by putative tumor suppressor DBC1

    SciTech Connect

    Koyama, Satoshi; Wada-Hiraike, Osamu; Nakagawa, Shunsuke; Tanikawa, Michihiro; Hiraike, Haruko; Miyamoto, Yuichiro; Sone, Kenbun; Oda, Katsutoshi; Fukuhara, Hiroshi; Nakagawa, Keiichi; Kato, Shigeaki; Yano, Tetsu; Taketani, Yuji

    2010-02-12

    It has been well established that estrogen is involved in the pathophysiology of breast cancer. Estrogen receptor (ER) {alpha} appears to promote the proliferation of cancer tissues, while ER{beta} can protect against the mitogenic effect of estrogen in breast tissue. The expression status of ER{alpha} and ER{beta} may greatly influence on the development, treatment, and prognosis of breast cancer. Previous studies have indicated that the deleted in breast cancer 1 (DBC1/KIAA1967) gene product has roles in regulating functions of nuclear receptors. The gene encoding DBC1 is a candidate for tumor suppressor identified by genetic search for breast cancer. Caspase-dependent processing of DBC1 promotes apoptosis, and depletion of the endogenous DBC1 negatively regulates p53-dependent apoptosis through its specific inhibition of SIRT1. In addition, DBC1 modulates ER{alpha} expression and promotes breast cancer cell survival by binding to ER{alpha}. Here we report an ER{beta}-specific repressive function of DBC1. Immunoprecipitation and immunofluorescence studies show that ER{beta} and DBC1 interact in a ligand-independent manner similar to ER{alpha}. In vitro pull-down assays revealed a direct interaction between DBC1 amino-terminus and activation function-1/2 domain of ER{beta}. Although DBC1 shows no influence on the ligand-dependent transcriptional activation function of ER{alpha}, the expression of DBC1 negatively regulates the ligand-dependent transcriptional activation function of ER{beta}in vivo, and RNA interference-mediated depletion of DBC1 stimulates the transactivation function of ER{beta}. These results implicate the principal role of DBC1 in regulating ER{beta}-dependent gene expressions.

  10. Mechanism of inhibition of the tumor suppressor Patched by Sonic Hedgehog.

    PubMed

    Tukachinsky, Hanna; Petrov, Kostadin; Watanabe, Miyako; Salic, Adrian

    2016-10-04

    The Hedgehog cell-cell signaling pathway is crucial for animal development, and its misregulation is implicated in numerous birth defects and cancers. In unstimulated cells, pathway activity is inhibited by the tumor suppressor membrane protein, Patched. Hedgehog signaling is triggered by the secreted Hedgehog ligand, which binds and inhibits Patched, thus setting in motion the downstream events in signal transduction. Despite its critical importance, the mechanism by which Hedgehog antagonizes Patched has remained unknown. Here, we show that vertebrate Patched1 inhibition is caused by direct, palmitate-dependent interaction with the Sonic Hedgehog ligand. We find that a short palmitoylated N-terminal fragment of Sonic Hedgehog binds Patched1 and, strikingly, is sufficient to inhibit it and to activate signaling. The rest of Sonic Hedgehog confers high-affinity Patched1 binding and internalization through a distinct binding site, but, surprisingly, it is not absolutely required for signaling. The palmitate-dependent interaction with Patched1 is specifically impaired in a Sonic Hedgehog mutant causing human holoprosencephaly, the most frequent congenital brain malformation, explaining its drastically reduced potency. The palmitate-dependent interaction is also abolished in constitutively inhibited Patched1 point mutants causing the Gorlin cancer syndrome, suggesting that they might adopt a conformation distinct from the wild type. Our data demonstrate that Sonic Hedgehog signals via the palmitate-dependent arm of a two-pronged contact with Patched1. Furthermore, our results suggest that, during Hedgehog signaling, ligand binding inhibits Patched by trapping it in an inactive conformation, a mechanism that explains the dramatically reduced activity of oncogenic Patched1 mutants.

  11. Mechanism of inhibition of the tumor suppressor Patched by Sonic Hedgehog

    PubMed Central

    Tukachinsky, Hanna; Petrov, Kostadin; Watanabe, Miyako; Salic, Adrian

    2016-01-01

    The Hedgehog cell–cell signaling pathway is crucial for animal development, and its misregulation is implicated in numerous birth defects and cancers. In unstimulated cells, pathway activity is inhibited by the tumor suppressor membrane protein, Patched. Hedgehog signaling is triggered by the secreted Hedgehog ligand, which binds and inhibits Patched, thus setting in motion the downstream events in signal transduction. Despite its critical importance, the mechanism by which Hedgehog antagonizes Patched has remained unknown. Here, we show that vertebrate Patched1 inhibition is caused by direct, palmitate-dependent interaction with the Sonic Hedgehog ligand. We find that a short palmitoylated N-terminal fragment of Sonic Hedgehog binds Patched1 and, strikingly, is sufficient to inhibit it and to activate signaling. The rest of Sonic Hedgehog confers high-affinity Patched1 binding and internalization through a distinct binding site, but, surprisingly, it is not absolutely required for signaling. The palmitate-dependent interaction with Patched1 is specifically impaired in a Sonic Hedgehog mutant causing human holoprosencephaly, the most frequent congenital brain malformation, explaining its drastically reduced potency. The palmitate-dependent interaction is also abolished in constitutively inhibited Patched1 point mutants causing the Gorlin cancer syndrome, suggesting that they might adopt a conformation distinct from the wild type. Our data demonstrate that Sonic Hedgehog signals via the palmitate-dependent arm of a two-pronged contact with Patched1. Furthermore, our results suggest that, during Hedgehog signaling, ligand binding inhibits Patched by trapping it in an inactive conformation, a mechanism that explains the dramatically reduced activity of oncogenic Patched1 mutants. PMID:27647915

  12. Allostery mediates ligand binding to WWOX tumor suppressor via a conformational switch.

    PubMed

    Schuchardt, Brett J; Mikles, David C; Bhat, Vikas; McDonald, Caleb B; Sudol, Marius; Farooq, Amjad

    2015-04-01

    While being devoid of the ability to recognize ligands itself, the WW2 domain is believed to aid ligand binding to the WW1 domain in the context of a WW1-WW2 tandem module of WW domain-containing oxidoreductase (WWOX) tumor suppressor. In an effort to test the generality of this hypothesis, we have undertaken here a detailed biophysical analysis of the binding of WW domains of WWOX alone and in the context of the WW1-WW2 tandem module to an array of putative proline-proline-x-tyrosine (PPXY) ligands. Our data show that while the WW1 domain of WWOX binds to all ligands in a physiologically relevant manner, the WW2 domain does not. Moreover, ligand binding to the WW1 domain in the context of the WW1-WW2 tandem module is two-to-three-fold stronger than when treated alone. We also provide evidence that the WW domains within the WW1-WW2 tandem module physically associate so as to adopt a fixed spatial orientation relative to each other. Of particular note is the observation that the physical association of the WW2 domain with WW1 blocks access to ligands. Consequently, ligand binding to the WW1 domain not only results in the displacement of the WW2 lid but also disrupts the physical association of WW domains in the liganded conformation. Taken together, our study underscores a key role of allosteric communication in the ability of the WW2 orphan domain to chaperone physiological action of the WW1 domain within the context of the WW1-WW2 tandem module of WWOX.

  13. Cellular retinol binding protein 1 could be a tumor suppressor gene in cervical cancer

    PubMed Central

    Mendoza-Rodriguez, Mónica; Arreola, Hugo; Valdivia, Alejandra; Peralta, Raúl; Serna, Humberto; Villegas, Vanessa; Romero, Pablo; Alvarado-Hernández, Beatriz; Paniagua, Lucero; Marrero-Rodríguez, Daniel; Meraz, Marco A; Salcedo, Mauricio

    2013-01-01

    Aims: Cervical Cancer (CC) is one of the most important health problems in women. It frequently presents genetic changes at chromosome region 3q21. This region contains the Cellular Retinol Binding Protein 1 gene (CRBP1) which has been implicated as an important element in the development of other types of cancer. The main goal of the present work was to determine the molecular alterations of CRBP1 and its relationship to CC. Methods: To determine the molecular alterations of CRBP1 gene in CC; twenty-six CC and twenty-six healthy cervix samples were evaluated for: 1) Copy number gain by real-time PCR analysis, 2) expression levels by an immunohistochemistry assay on tissue microarray, and 3) the methylation status of the CRBP1 promoter region. Results: The increase in CRBP1 copy number was observed in 10 out of the 26 CC samples analyzed, while healthy cervices samples showed no changes in the copy number. In addition, there was a lack of expression of the CRBP1 gene in an important number of the CC samples (17/26), and the CRBP1 gene promoter was methylated in 15/26 of the CC samples. Interestingly, there was a significant association between the lack of expression of the CRBP1 gene and its methylation status. Conclusions: The data indicates that, both activating and inactivating changes in the CRBP1 gene could be significant events in the development and progression of CC, and the lack of expression of the CRBP1 protein could be related with to the development of CC. We believe that there is enough evidence to consider to CRBP1 gene as a tumor suppressor gene for CC. PMID:24040446

  14. In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

    PubMed Central

    Lv, Juan; Zhu, Qiaoying; Jia, Xuemei; Yu, Ningzhu; Li, Qian

    2016-01-01

    Background Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. Material/Methods PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. Results PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. Conclusions PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis. PMID:27744455

  15. Aberrant DNA methylation of some tumor suppressor genes in lung cancers from workers with chromate exposure.

    PubMed

    Ali, Abdellah H K; Kondo, Kazuya; Namura, Toshiaki; Senba, Yoshitaka; Takizawa, Hiromitsu; Nakagawa, Yasushi; Toba, Hiroaki; Kenzaki, Koichiro; Sakiyama, Shoji; Tangoku, Akira

    2011-02-01

    Our previous studies revealed a variety of genetic changes in lung cancers from chromate-exposed workers (chromate lung cancer). In the present study, we examined epigenetic changes in chromate lung cancers. Nested-methylation-specific PCR was employed in studying the methylation of CpG islands in the APC, MGMT, hMLH1 genes in 36 chromate lung cancers and 25 nonchromate lung cancers. Methylation in chromate lung cancers was detected at 86% for APC, 20% for MGMT, and 28% for hMLH1. Whereas, it occurred at lower frequencies in nonchromate lung cancers, particularly in APC (44%) and hMLH1 (0%) genes. Our previous study showed that methylation of p16 gene in chromate lung cancer and nonchromate lung cancer was 33% and 26%, respectively. The mean methylation index (MI), a reflection of the overall methylation status, was significantly higher in chromate lung cancers than nonchromate lung cancers (0.41 vs. 0.21, P=0.001). Methylation of multiple genes (particularly hMLH1, p16, and APC genes) had experienced more than 15 yr of chromate exposure in chromate lung cancer (MI: <15 yr; 0.19, ≥ 15 yr, 0.42). There is a significant correlation of p16 and hMLH1 methylation with the expressional decrease or loss of the corresponding gene products (P=0.037 and 0.024) respectively, and an inverse correlation between APC and MGMT methylation (P = 0.014). This study provides a novel evidence for the chromium carcinogenesis that chromate lung cancer is linked to the progressive methylation of some tumor suppressor genes, which may be related to genomic instability.

  16. RAP1GA1: A candidate tumor suppressor locus in 1p36.1

    SciTech Connect

    Ranade, K.; Hussussian, C.J.; Higgins, P.

    1994-09-01

    The rap1/Krev-1 gene (RAP1A) encodes a p21-related protein that suppresses transformation by activated p21{sup ras}. The GTPase activating protein (GAP) gene for p21{sup rap1A} (RAP1GA1) has recently been assigned to chromosome 1p36.1-p35, a region of the genome that is frequently involved in deletions and rearrangements in several different tumors including breast, colon and hepatocellular carcinomas, melanoma, and neuroblastoma. GAP genes negatively regulate the activity of p21 proteins by catalyzing the conversion of the active GTP-bound forms to the inactive GDP-bound forms. The physiological function of p21{sup rap1A}-GAP makes it a strong candidate as a tumor suppressor gene that may have a role in the development of one or more of these malignancies. We have refined the localization of RAP1GA1 by linkage analysis with a highly informative (CA){sub n} repeat contained within the gene, and demonstrated that it is within the minimal deleted region for breast and colon carcinomas, and that it is excluded from the minimally deleted region in melanoma and neuroblastoma. Genetic mapping in the mouse demonstrated that Rap1ga1 is located {approximately}10 cM proximal to Pnd and therefore maps within the interval containing the modifier of Min gene (Mom-1) and the plasmocytoma susceptibility locus (Pcts). The human RAP1GA1 gene contains at least 27 exons. The coding region contains 22 exons, and there are at least five 5{prime}-UT exons that are assembled in a complex pattern of alternative splicing in different tissues. The localization of RAP1GA1 makes it a very strong candidate for a role as a modifier gene involved in the common secondary abnormalities involving 1p36 in several different carcinomas. The potential role of RAP1GA1 in these malignancies is currently being investigated by sequence analysis of breast and colon carcinomas with loss of heterozygosity in 1p36.

  17. Physical and functional interactions between the Wwox tumor suppressor protein and the AP-2gamma transcription factor.

    PubMed

    Aqeilan, Rami I; Palamarchuk, Alexey; Weigel, Ronald J; Herrero, Juan J; Pekarsky, Yuri; Croce, Carlo M

    2004-11-15

    The WWOX gene encodes a tumor suppressor WW domain-containing protein, Wwox. Alterations of WWOX have been demonstrated in multiple types of cancer, and introduction of Wwox into Wwox-negative tumor cells has resulted in tumor suppression and apoptosis. The Wwox protein contains two WW domains that typically bind proline-rich motifs and mediate protein-protein interactions. Recently, we have described functional cross-talk between the Wwox protein and the p53 homologue, p73. To further explore the biological function of Wwox, we investigated other interacting candidates. In this report, we demonstrate a physical and functional association between AP-2gamma transcription factor and the Wwox protein. AP-2gamma at 20q13.2 encodes a transcription factor and is frequently amplified in breast carcinoma. We show that Wwox binds to the PPPY motif of AP-2gamma via its first WW domain. Alterations of tyrosine 33 in the first WW domain of Wwox or the proline-rich motif in AP-2gamma dramatically reduce this interaction. In addition, our results demonstrate that Wwox expression triggers redistribution of nuclear AP-2gamma to the cytoplasm, hence suppressing its transactivating function. Our results suggest that Wwox tumor suppressor protein inhibits AP-2gamma oncogenic activity by sequestering it in the cytoplasm.

  18. Alternating expression levels of WWOX tumor suppressor and cancer-related genes in patients with bladder cancer

    PubMed Central

    PŁUCIENNIK, ELŻBIETA; NOWAKOWSKA, MAGDALENA; STĘPIEN, ANNA; WOŁKOWICZ, MATEUSZ; STAWIŃSKI, ADAM; RÓŻAŃSKI, WALDEMAR; LIPIŃSKI, MAREK; BEDNAREK, ANDRZEJ K

    2014-01-01

    The aim of the present study was to determine the roles of the WWOX tumor suppressor and cancer-related genes in bladder tumor carcinogenesis. Reverse transcription-quantitative polymerase chain reaction was used to analyze the status of WWOX promoter methylation (using MethylScreen™ technology) and loss of heterozygosity (LOH) in papillary urothelial cancer tissues. The associations between the expression levels of the following tumorigenesis-related genes were also assessed: The WWOX tumor suppressor gene, the MKI67 proliferation gene, the BAX, BCL2 and BIRC5 apoptotic genes, the EGFR signal transduction gene, the VEGF vascular endothelial growth factor gene, and the CCND1 and CCNE1 cell cycle genes. The results reveal a high frequency of LOH in intron 1 in the WWOX gene, as well as an association between reduced WWOX expression levels and increased promoter methylation. In addition, the present study demonstrates that in bladder tumors, apoptosis is inhibited by increased expression levels of the BCL2 gene. A correlation between the proliferation indices of the MKI67 and the BIRC5 genes was also revealed. Furthermore, the expression levels of VEGF were identified to be positively associated with those of the EGFR gene. PMID:25295115

  19. Genome-wide DNA methylation analysis identifies MEGF10 as a novel epigenetically repressed candidate tumor suppressor gene in neuroblastoma.

    PubMed

    Charlet, Jessica; Tomari, Ayumi; Dallosso, Anthony R; Szemes, Marianna; Kaselova, Martina; Curry, Thomas J; Almutairi, Bader; Etchevers, Heather C; McConville, Carmel; Malik, Karim T A; Brown, Keith W

    2017-04-01

    Neuroblastoma is a childhood cancer in which many children still have poor outcomes, emphasising the need to better understand its pathogenesis. Despite recent genome-wide mutation analyses, many primary neuroblastomas do not contain recognizable driver mutations, implicating alternate molecular pathologies such as epigenetic alterations. To discover genes that become epigenetically deregulated during neuroblastoma tumorigenesis, we took the novel approach of comparing neuroblastomas to neural crest precursor cells, using genome-wide DNA methylation analysis. We identified 93 genes that were significantly differentially methylated of which 26 (28%) were hypermethylated and 67 (72%) were hypomethylated. Concentrating on hypermethylated genes to identify candidate tumor suppressor loci, we found the cell engulfment and adhesion factor gene MEGF10 to be epigenetically repressed by DNA hypermethylation or by H3K27/K9 methylation in neuroblastoma cell lines. MEGF10 showed significantly down-regulated expression in neuroblastoma tumor samples; furthermore patients with the lowest-expressing tumors had reduced relapse-free survival. Our functional studies showed that knock-down of MEGF10 expression in neuroblastoma cell lines promoted cell growth, consistent with MEGF10 acting as a clinically relevant, epigenetically deregulated neuroblastoma tumor suppressor gene. © 2016 The Authors. Molecular Carcinogenesis Published by Wiley Periodicals, Inc.

  20. The HRPT2 tumor suppressor gene product parafibromin associates with human PAF1 and RNA polymerase II.

    PubMed

    Yart, Armelle; Gstaiger, Matthias; Wirbelauer, Christiane; Pecnik, Maria; Anastasiou, Dimitrios; Hess, Daniel; Krek, Wilhelm

    2005-06-01

    Inactivation of the HRPT2 tumor suppressor gene is associated with the pathogenesis of the hereditary hyperparathyroidism-jaw tumor syndrome and malignancy in sporadic parathyroid tumors. The cellular function of the HPRT2 gene product, parafibromin, has not been defined yet. Here we show that parafibromin physically interacts with human orthologs of yeast Paf1 complex components, including PAF1, LEO1, and CTR9, that are involved in transcription elongation and 3' end processing. It also associates with modified forms of the large subunit of RNA polymerase II, in particular those phosphorylated on serine 5 or 2 within the carboxy-terminal domain, that are important for the coordinate recruitment of transcription elongation and RNA processing machineries during the transcription cycle. These interactions depend on a C-terminal domain of parafibromin, which is deleted in ca. 80% of clinically relevant mutations. Finally, RNAi-induced downregulation of parafibromin promotes entry into S phase, implying a role for parafibromin as an inhibitor of cell cycle progression. Taken together, these findings link the tumor suppressor parafibromin to the transcription elongation and RNA processing pathway as a PAF1 complex- and RNA polymerase II-bound protein. Dysfunction of this pathway may be a general phenomenon in the majority of cases of hereditary parathyroid cancer.

  1. The HRPT2 Tumor Suppressor Gene Product Parafibromin Associates with Human PAF1 and RNA Polymerase II

    PubMed Central

    Yart, Armelle; Gstaiger, Matthias; Wirbelauer, Christiane; Pecnik, Maria; Anastasiou, Dimitrios; Hess, Daniel; Krek, Wilhelm

    2005-01-01

    Inactivation of the HRPT2 tumor suppressor gene is associated with the pathogenesis of the hereditary hyperparathyroidism-jaw tumor syndrome and malignancy in sporadic parathyroid tumors. The cellular function of the HPRT2 gene product, parafibromin, has not been defined yet. Here we show that parafibromin physically interacts with human orthologs of yeast Paf1 complex components, including PAF1, LEO1, and CTR9, that are involved in transcription elongation and 3′ end processing. It also associates with modified forms of the large subunit of RNA polymerase II, in particular those phosphorylated on serine 5 or 2 within the carboxy-terminal domain, that are important for the coordinate recruitment of transcription elongation and RNA processing machineries during the transcription cycle. These interactions depend on a C-terminal domain of parafibromin, which is deleted in ca. 80% of clinically relevant mutations. Finally, RNAi-induced downregulation of parafibromin promotes entry into S phase, implying a role for parafibromin as an inhibitor of cell cycle progression. Taken together, these findings link the tumor suppressor parafibromin to the transcription elongation and RNA processing pathway as a PAF1 complex- and RNA polymerase II-bound protein. Dysfunction of this pathway may be a general phenomenon in the majority of cases of hereditary parathyroid cancer. PMID:15923622

  2. The G-protein Alpha Subunit Gsα Is A Tumor Suppressor In Sonic Hedgehog-driven Medulloblastoma

    PubMed Central

    He, Xuelian; Zhang, Liguo; Chen, Ying; Remke, Marc; Shih, David; Lu, Fanghui; Wang, Haibo; Deng, Yaqi; Yu, Yang; Xia, Yong; Wu, Xiaochong; Ramaswamy, Vijay; Hu, Tom; Wang, Fan; Zhou, Wenhao; Burns, Dennis K.; Kim, Se Hoon; Kool, Marcel; Pfister, Stefan M.; Weinstein, Lee S.; Pomeroy, Scott L.; Gilbertson, Richard J.; Rubin, Joshua B.; Hou, Yiping; Wechsler-Reya, Robert; Taylor, Michael D.; Lu, Q. Richard

    2014-01-01

    Medulloblastoma, the most common malignant childhood brain tumor, exhibits distinct molecular subtypes and cellular origins. Genetic alterations driving medulloblastoma initiation and progression remain poorly understood. Herein, we identify GNAS, encoding the G-protein Gsα, as a potent tumor suppressor gene that defines a subset of aggressive Sonic Hedgehog (Shh)-driven human medulloblastomas. Ablation of the single Gnas gene in anatomically-distinct progenitors is sufficient to induce Shh-associated medulloblastomas, which recapitulate their human counterparts. Gsα is highly enriched at the primary cilium of granule neuron precursors and suppresses Shh-signaling by regulating both the cAMP-dependent pathway and ciliary trafficking of Hedgehog pathway components. Elevation of a Gsα effector, cAMP, effectively inhibits tumor cell proliferation and progression in Gnas mutants. Thus, our gain- and loss-of-function studies identify a previously unrecognized tumor suppressor function for Gsα that acts as a molecular link across Shh-group medulloblastomas of disparate cellular and anatomical origins, illuminating G-protein modulation as a potential therapeutic avenue. PMID:25150496

  3. Tumor Cell-Independent Estrogen Signaling Drives Disease Progression through Mobilization of Myeloid-Derived Suppressor Cells.

    PubMed

    Svoronos, Nikolaos; Perales-Puchalt, Alfredo; Allegrezza, Michael J; Rutkowski, Melanie R; Payne, Kyle K; Tesone, Amelia J; Nguyen, Jenny M; Curiel, Tyler J; Cadungog, Mark G; Singhal, Sunil; Eruslanov, Evgeniy B; Zhang, Paul; Tchou, Julia; Zhang, Rugang; Conejo-Garcia, Jose R

    2017-01-01

    The role of estrogens in antitumor immunity remains poorly understood. Here, we show that estrogen signaling accelerates the progression of different estrogen-insensitive tumor models by contributing to deregulated myelopoiesis by both driving the mobilization of myeloid-derived suppressor cells (MDSC) and enhancing their intrinsic immunosuppressive activity in vivo Differences in tumor growth are dependent on blunted antitumor immunity and, correspondingly, disappear in immunodeficient hosts and upon MDSC depletion. Mechanistically, estrogen receptor alpha activates the STAT3 pathway in human and mouse bone marrow myeloid precursors by enhancing JAK2 and SRC activity. Therefore, estrogen signaling is a crucial mechanism underlying pathologic myelopoiesis in cancer. Our work suggests that new antiestrogen drugs that have no agonistic effects may have benefits in a wide range of cancers, independently of the expression of estrogen receptors in tumor cells, and may synergize with immunotherapies to significantly extend survival.

  4. AZD1480 delays tumor growth in a melanoma model while enhancing the suppressive activity of myeloid-derived suppressor cells

    PubMed Central

    Maenhout, Sarah K.; Four, Stephanie Du; Corthals, Jurgen; Neyns, Bart; Thielemans, Kris; Aerts, Joeri L.

    2014-01-01

    AZD1480 is a potent, competitive small-molecule inhibitor of JAK1/2 kinase which inhibits STAT3 phosphorylation and tumor growth. Here we investigated the effects of AZD1480 on the function of different immune cell populations in a melanoma model. When MO4 tumor-bearing mice were treated with AZD1480 we observed a strong inhibition of tumor growth as well as a prolonged survival. Moreover, a significant decrease in the percentage of myeloid-derived suppressor cells (MDSCs) was observed after treatment with AZD1480. However, AZD1480 enhanced the suppressive capacity of murine MDSCs while at the same time impairing the proliferative as well as the IFN-γ secretion capacity of murine T cells. The addition of AZD1480 to co-cultures of human MDSCs and T cells does not affect the suppressive activity of MDSCs but it does reduce the IFN-γ secretion and the proliferative capacity of T cells. We showed that although AZD1480 has the ability to delay the tumor growth of MO4 tumor-bearing mice, this drug has detrimental effects on several aspects of the immune system. These data indicate that systemic targeting of the JAK/STAT pathway by JAK1/2 inhibition can have divergent effects on tumor growth and anti-tumor immune responses. PMID:25149535

  5. Myeloid-derived suppressor cells expand during breast cancer progression and promote tumor-induced bone destruction

    PubMed Central

    Danilin, Sabrina; Merkel, Alyssa R.; Johnson, Joshua R.; Johnson, Rachelle W.; Edwards, James R.; Sterling, Julie A.

    2012-01-01

    Myeloid-derived suppressor cells (MDSCs), identified as Gr1+CD11b+ cells in mice, expand during cancer and promote tumor growth, recurrence and burden. However, little is known about their role in bone metastases. We hypothesized that MDSCs may contribute to tumor-induced bone disease, and inoculated breast cancer cells into the left cardiac ventricle of nude mice. Disease progression was monitored weekly by X-ray and fluorescence imaging and MDSCs expansion by fluorescence-activated cell sorting. To explore the contribution of MDSCs to bone metastasis, we co-injected mice with tumor cells or PBS into the left cardiac ventricle and Gr1+CD11b+ cells isolated from healthy or tumor-bearing mice into the left tibia. MDSCs didn’t induce bone resorption in normal mice, but increased resorption and tumor burden significantly in tumor-bearing mice. In vitro experiments showed that Gr1+CD11b+ cells isolated from normal and tumor-bearing mice differentiate into osteoclasts when cultured with RANK ligand and macrophage colony-stimulating factor, and that MDSCs from tumor-bearing mice upregulate parathyroid hormone-related protein (PTHrP) mRNA levels in cancer cells. PTHrP upregulation is likely due to the 2-fold increase in transforming growth factor β expression that we observed in MDSCs isolated from tumor-bearing mice. Importantly, using MDSCs isolated from GFP-expressing animals, we found that MDSCs differentiate into osteoclast-like cells in tumor-bearing mice as evidenced by the presence of GFP+TRAP+ cells. These results demonstrate that MDSCs expand in breast cancer bone metastases and induce bone destruction. Furthermore, our data strongly suggest that MDSCs are able to differentiate into osteoclasts in vivo and that this is stimulated in the presence of tumors. PMID:23264895

  6. A catalog of genes homozygously deleted in human lung cancer and the candidacy of PTPRD as a tumor suppressor gene.

    PubMed

    Kohno, Takashi; Otsuka, Ayaka; Girard, Luc; Sato, Masanori; Iwakawa, Reika; Ogiwara, Hideaki; Sanchez-Cespedes, Montse; Minna, John D; Yokota, Jun

    2010-04-01

    A total of 176 genes homozygously deleted in human lung cancer were identified by DNA array-based whole genome scanning of 52 lung cancer cell lines and subsequent genomic PCR in 74 cell lines, including the 52 cell lines scanned. One or more exons of these genes were homozygously deleted in one (1%) to 20 (27%) cell lines. These genes included known tumor suppressor genes, e.g., CDKN2A/p16, RB1, and SMAD4, and candidate tumor suppressor genes whose hemizygous or homozygous deletions were reported in several types of human cancers, such as FHIT, KEAP1, and LRP1B/LRP-DIP. CDKN2A/p16 and p14ARF located in 9p21 were most frequently deleted (20/74, 27%). The PTPRD gene was most frequently deleted (8/74, 11%) among genes mapping to regions other than 9p21. Somatic mutations, including a nonsense mutation, of the PTPRD gene were detected in 8/74 (11%) of cell lines and 4/95 (4%) of surgical specimens of lung cancer. Reduced PTPRD expression was observed in the majority (>80%) of cell lines and surgical specimens of lung cancer. Therefore, PTPRD is a candidate tumor suppressor gene in lung cancer. Microarray-based expression profiling of 19 lung cancer cell lines also indicated that some of the 176 genes, such as KANK and ADAMTS1, are preferentially inactivated by epigenetic alterations. Genetic/epigenetic as well as functional studies of these 176 genes will increase our understanding of molecular mechanisms behind lung carcinogenesis.

  7. RGS6 is an essential tumor suppressor that prevents bladder carcinogenesis by promoting p53 activation and DNMT1 downregulation.

    PubMed

    Yang, Jianqi; Platt, Lance T; Maity, Biswanath; Ahlers, Katelin E; Luo, Zili; Lin, Zhibo; Chakravarti, Bandana; Ibeawuchi, Stella-Rita; Askeland, Ryan W; Bondaruk, Jolanta; Czerniak, Bogdan A; Fisher, Rory A

    2016-10-25

    Urinary bladder cancer (UBC) is largely caused by exposure to toxic chemicals including those in cigarette smoke (i.e. BBN). An activating SNP in RGS6 is associated with a pronounced reduction in UBC risk, especially among smokers. However, the mechanism underlying this reduction remains unknown. Here we demonstrate that RGS6 is robustly expressed in human urothelium, where urothelial cell carcinoma originates, and is downregulated in human UBC. Utilizing RGS6-/- mice we interrogated a possible role for RGS6 as a tumor suppressor using the BBN-induced bladder carcinogenesis model that closely recapitulates human disease. As in humans, RGS6 is robustly expressed in mouse urothelium. RGS6 loss dramatically accelerates BBN-induced bladder carcinogenesis, with RGS6-/- mice consistently displaying more advanced pathological lesions than RGS6+/+ mice. Furthermore, BBN treatment promotes urothelial RGS6 mRNA and protein downregulation. RGS6 loss impairs p53 activation and promotes aberrant accumulation of oncogenic protein DNMT1 in urothelium. Tumor suppressor RASSF1A, a DNMT1-regulated gene, is also silenced, likely via methylation of its promoter during BBN exposure. We hypothesize that this BBN-induced RGS6 loss represents a critical hit in UBC as it irrevocably impairs the anti-proliferative actions of the ATM/p53 and RASSF1A pathways. Consistent with these findings, RGS6-/- mice treated with CP-31398, a p53-stablizing agent, and/or 5-Aza, a DNMT1 inhibitor, are protected from BBN-induced tumorigenesis. Together, our data identify RGS6 as a master tumor suppressor modulating two critical signaling pathways that are often dysregulated in UBC; therefore, RGS6 represents a potential novel biomarker for UBC diagnosis/prognosis and an appealing new target in its treatment.

  8. RGS6 is an essential tumor suppressor that prevents bladder carcinogenesis by promoting p53 activation and DNMT1 downregulation

    PubMed Central

    Yang, Jianqi; Platt, Lance T.; Maity, Biswanath; Ahlers, Katelin E.; Luo, Zili; Lin, Zhibo; Chakravarti, Bandana; Ibeawuchi, Stella-Rita; Askeland, Ryan W.; Bondaruk, Jolanta; Czerniak, Bogdan A.; Fisher, Rory A.

    2016-01-01

    Urinary bladder cancer (UBC) is largely caused by exposure to toxic chemicals including those in cigarette smoke (i.e. BBN). An activating SNP in RGS6 is associated with a pronounced reduction in UBC risk, especially among smokers. However, the mechanism underlying this reduction remains unknown. Here we demonstrate that RGS6 is robustly expressed in human urothelium, where urothelial cell carcinoma originates, and is downregulated in human UBC. Utilizing RGS6−/− mice we interrogated a possible role for RGS6 as a tumor suppressor using the BBN-induced bladder carcinogenesis model that closely recapitulates human disease. As in humans, RGS6 is robustly expressed in mouse urothelium. RGS6 loss dramatically accelerates BBN-induced bladder carcinogenesis, with RGS6−/− mice consistently displaying more advanced pathological lesions than RGS6+/+ mice. Furthermore, BBN treatment promotes urothelial RGS6 mRNA and protein downregulation. RGS6 loss impairs p53 activation and promotes aberrant accumulation of oncogenic protein DNMT1 in urothelium. Tumor suppressor RASSF1A, a DNMT1-regulated gene, is also silenced, likely via methylation of its promoter during BBN exposure. We hypothesize that this BBN-induced RGS6 loss represents a critical hit in UBC as it irrevocably impairs the anti-proliferative actions of the ATM/p53 and RASSF1A pathways. Consistent with these findings, RGS6−/− mice treated with CP-31398, a p53-stablizing agent, and/or 5-Aza, a DNMT1 inhibitor, are protected from BBN-induced tumorigenesis. Together, our data identify RGS6 as a master tumor suppressor modulating two critical signaling pathways that are often dysregulated in UBC; therefore, RGS6 represents a potential novel biomarker for UBC diagnosis/prognosis and an appealing new target in its treatment. PMID:27713144

  9. A Catalog of Genes Homozygously Deleted in Human Lung Cancer and the Candidacy of PTPRD as a Tumor Suppressor Gene

    PubMed Central

    Kohno, Takashi; Otsuka, Ayaka; Girard, Luc; Sato, Masanori; Iwakawa, Reika; Ogiwara, Hideaki; Sanchez-Cespedes, Montse; Minna, John D.; Yokota, Jun

    2010-01-01

    A total of 176 genes homozygously deleted in human lung cancer were identified by DNA array-based whole genome scanning of 52 lung cancer cell lines and subsequent genomic PCR in 74 cell lines, including the 52 cell lines scanned. One or more exons of these genes were homozygously deleted in one (1%) to 20 (27%) cell lines. These genes included known tumor suppressor genes, e.g., CDKN2A/p16, RB1, and SMAD4, and candidate tumor suppressor genes whose hemizygous or homozygous deletions were reported in several types of human cancers, such as FHIT, KEAP1, and LRP1B/LRP-DIP. CDKN2A/p16 and p14ARF located in 9p21 were most frequently deleted (20/74, 27%). The PTPRD gene was most frequently deleted (8/74, 11%) among genes mapping to regions other than 9p21. Somatic mutations, including a nonsense mutation, of the PTPRD gene were detected in 8/74 (11%) of cell lines and 4/95 (4%) of surgical specimens of lung cancer. Reduced PTPRD expression was observed in the majority (>80%) of cell lines and surgical specimens of lung cancer. Therefore, PTPRD is a candidate tumor suppressor gene in lung cancer. Microarray-based expression profiling of 19 lung cancer cell lines also indicated that some of the 176 genes, such as KANK and ADAMTS1, are preferentially inactivated by epigenetic alterations. Genetic/epigenetic as well as functional studies of these 176 genes will increase our understanding of molecular mechanisms behind lung carcinogenesis. PMID:20073072

  10. CHK2-BRCA1 tumor-suppressor axis restrains oncogenic Aurora-A kinase to ensure proper mitotic microtubule assembly.

    PubMed

    Ertych, Norman; Stolz, Ailine; Valerius, Oliver; Braus, Gerhard H; Bastians, Holger

    2016-02-16

    BRCA1 (breast cancer type 1 susceptibility protein) is a multifunctional tumor suppressor involved in DNA damage response, DNA repair, chromatin regulation, and mitotic chromosome segregation. Although the nuclear functions of BRCA1 have been investigated in detail, its role during mitosis is little understood. It is clear, however, that loss of BRCA1 in human cancer cells leads to chromosomal instability (CIN), which is defined as a perpetual gain or loss of whole chromosomes during mitosis. Moreover, our recent work has revealed that the mitotic function of BRCA1 depends on its phosphorylation by the tumor-suppressor kinase Chk2 (checkpoint kinase 2) and that this regulation is required to ensure normal microtubule plus end assembly rates within mitotic spindles. Intriguingly, loss of the positive regulation of BRCA1 leads to increased oncogenic Aurora-A activity, which acts as a mediator for abnormal mitotic microtubule assembly resulting in chromosome missegregation and CIN. However, how the CHK2-BRCA1 tumor suppressor axis restrains oncogenic Aurora-A during mitosis to ensure karyotype stability remained an open question. Here we uncover a dual molecular mechanism by which the CHK2-BRCA1 axis restrains oncogenic Aurora-A activity during mitosis and identify BRCA1 itself as a target for Aurora-A relevant for CIN. In fact, Chk2-mediated phosphorylation of BRCA1 is required to recruit the PP6C-SAPS3 phosphatase, which acts as a T-loop phosphatase inhibiting Aurora-A bound to BRCA1. Consequently, loss of CHK2 or PP6C-SAPS3 promotes Aurora-A activity associated with BRCA1 in mitosis. Aurora-A, in turn, then phosphorylates BRCA1 itself, thereby inhibiting the mitotic function of BRCA1 and promoting mitotic microtubule assembly, chromosome missegregation, and CIN.

  11. The von Hippel-Lindau tumor suppressor protein is a component of an E3 ubiquitin-protein ligase activity.

    PubMed

    Lisztwan, J; Imbert, G; Wirbelauer, C; Gstaiger, M; Krek, W

    1999-07-15

    pVHL, the product of the VHL tumor suppressor gene, plays an important role in the regulation of cell growth and differentiation of human kidney cells, and inactivation of the VHL gene is the most frequent genetic event in human kidney cancer. The biochemical function of pVHL is unknown. Here we report that pVHL exists in vivo in a complex that displays ubiquitination-promoting activity in conjunction with the universally required components E1, E2, and ubiquitin. pVHL-associated ubiquitination activity requires, at a minimum, pVHL to bind elongin C and Cul-2, relatives of core components of SCF (Skp1-Cdc53/Cul-1-F-box protein) E3 ligase complexes. Notably, certain tumor-derived mutants of pVHL demonstrate loss of associated ubiquitination promoting activity. These results identify pVHL as a component of a potential SCF-like E3 ubiquitin-protein ligase complex and suggest a direct link between pVHL tumor suppressor and the process of ubiquitination.

  12. Inactivation of the PBRM1 tumor suppressor gene amplifies the HIF-response in VHL-/- clear cell renal carcinoma.

    PubMed

    Gao, Wenhua; Li, Wei; Xiao, Tengfei; Liu, Xiaole Shirley; Kaelin, William G

    2017-01-31

    Most clear cell renal carcinomas (ccRCCs) are initiated by somatic inactivation of the VHL tumor suppressor gene. The VHL gene product, pVHL, is the substrate recognition unit of an ubiquitin ligase that targets the HIF transcription factor for proteasomal degradation; inappropriate expression of HIF target genes drives renal carcinogenesis. Loss of pVHL is not sufficient, however, to cause ccRCC. Additional cooperating genetic events, including intragenic mutations and copy number alterations, are required. Common examples of the former are loss-of-function mutations of the PBRM1 and BAP1 tumor suppressor genes, which occur in a mutually exclusive manner in ccRCC and define biologically distinct subsets of ccRCC. PBRM1 encodes the Polybromo- and BRG1-associated factors-containing complex (PBAF) chromatin remodeling complex component BRG1-associated factor 180 (BAF180). Here we identified ccRCC lines whose ability to proliferate in vitro and in vivo is sensitive to wild-type BAF180, but not a tumor-associated BAF180 mutant. Biochemical and functional studies linked growth suppression by BAF180 to its ability to form a canonical PBAF complex containing BRG1 that dampens the HIF transcriptional signature.

  13. Tuberin, the tuberous sclerosis complex 2 tumor suppressor gene product, regulates Rho activation, cell adhesion and migration.

    PubMed

    Astrinidis, Aristotelis; Cash, Timothy P; Hunter, Deborah S; Walker, Cheryl L; Chernoff, Jonathan; Henske, Elizabeth P

    2002-12-05

    Tuberous sclerosis complex (TSC) is a tumor suppressor gene syndrome characterized by seizures, mental retardation, autism, and tumors of the brain, kidney, heart, retina, and skin. TSC is caused by mutations in either TSC1 or TSC2, both of which are tumor suppressor genes. Hamartin, the protein product of TSC1, was found to interact with the ezrin-radixin-moesin family of cytoskeletal proteins and to activate the small GTPase Rho. To determine whether tuberin, the TSC2 product, can also activate Rho, we stably expressed full-length human tuberin in two cell types: MDCK cells and ELT3 cells. ELT3 cells lack endogenous tuberin expression. We found that expression of human tuberin in both MDCK and ELT3 cells was associated with an increase in the amount of Rho-GTP, but not in Rac1-GTP or cdc42-GTP. Tuberin expression increased cell adhesion in both cell types, and decreased chemotactic cell migration in ELT3 cells. In MDCK cells, there was a decrease in the amount of total Focal Adhesion Kinase (FAK) and an increase in the fraction of phosphorylated FAK. These findings demonstrate for the first time that tuberin activates Rho and regulates cell adhesion and migration. Pathways involving Rho activation may have relevance to the clinical manifestations of TSC, including pulmonary lymphangioleiomyomatosis.

  14. The von Hippel–Lindau tumor suppressor gene is required for cell cycle exit upon serum withdrawal

    PubMed Central

    Pause, Arnim; Lee, Stephen; Lonergan, Kim M.; Klausner, Richard D.

    1998-01-01

    The inactivation of the von Hippel–Lindau (VHL) tumor suppressor gene predisposes affected individuals to the human VHL cancer syndrome and is associated with sporadic renal cell carcinomas (RCC) and brain hemangioblastomas. VHL-negative 786–0 RCC cells are tumorigenic in nude mice which is suppressed by the reintroduction of VHL. Remarkably, this occurs without affecting the growth rate and cell cycle profile of these cells in culture. The 786–0 cell line, like many cancer cells, fails to exit the cell cycle upon serum withdrawal. Here, it is shown that reintroduction of the wild-type VHL gene restores the ability of VHL-negative RCC cancer cells to exit the cell cycle and enter G0/quiescence in low serum. Both VHL-positive and VHL-negative RCC cells exit the cell cycle by contact inhibition. The cyclin-dependent kinase inhibitor, p27, accumulates upon serum withdrawal, only in the presence of VHL, as a result of the stabilization of the protein. We propose that the loss of wild-type VHL gene results in a specific cellular defect in serum-dependent growth control, which may initiate tumor formation. This is corrected by the reintroduction of wild-type VHL, implicating VHL as the first tumor suppressor involved in the regulation of cell cycle exit, which is consistent with its gatekeeper function in the kidney. PMID:9448273

  15. Regulation of intracellular beta-catenin levels by the adenomatous polyposis coli (APC) tumor-suppressor protein.

    PubMed Central

    Munemitsu, S; Albert, I; Souza, B; Rubinfeld, B; Polakis, P

    1995-01-01

    The APC tumor-suppressor protein associates with beta-catenin, a cell adhesion protein that is upregulated by the WNT1 oncogene. We examined the effects of exogenous APC expression on the distribution and amount of beta-catenin in a colorectal cancer cell containing only mutant APC. Expression of wild-type APC caused a pronounced reduction in total beta-catenin levels by eliminating an excessive supply of cytoplasmic beta-catenin indigenous to the SW480 colorectal cancer cell line. This reduction was due to an enhanced rate of beta-catenin protein degradation. Truncated mutant APC proteins, characteristic of those associated with cancer, lacked this activity. Mutational analysis revealed that the central region of the APC protein, which is typically deleted or severely truncated in tumors, was responsible for the down-regulation of beta-catenin. These results suggest that the tumor-suppressor activity of mutant APC may be compromised due to a defect in its ability to regulate beta-catenin. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:7708772

  16. SIGNALING TO THE P53 TUMOR SUPPRESSOR THROUGH PATHWAYS ACTIVATED BY GENOTOXIC AND NON-GENOTOXIC STRESSES.

    SciTech Connect

    ANDERSON,C.W.APPELLA,E.

    2002-07-01

    The p53 tumor suppressor is a tetrameric transcription factor that is post-translational modified at {approx}18 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review the posttranslational modifications to p53 and the pathways that produce them in response to both genotoxic and non-genotoxic stresses.

  17. Grape seed proanthocyanidins reactivate silenced tumor suppressor genes in human skin cancer cells by targeting epigenetic regulators

    SciTech Connect

    Vaid, Mudit; Prasad, Ram; Singh, Tripti; Jones, Virginia; Katiyar, Santosh K.

    2012-08-15

    Grape seed proanthocyanidins (GSPs) have been shown to have anti-skin carcinogenic effects in in vitro and in vivo models. However, the precise epigenetic molecular mechanisms remain unexplored. This study was designed to investigate whether GSPs reactivate silenced tumor suppressor genes following epigenetic modifications in skin cancer cells. For this purpose, A431 and SCC13 human squamous cell carcinoma cell lines were used as in vitro models. The effects of GSPs on DNA methylation, histone modifications and tumor suppressor gene expressions were studied in these cell lines using enzyme activity assays, western blotting, dot-blot analysis and real-time polymerase chain reaction (RT-PCR). We found that treatment of A431 and SCC13 cells with GSPs decreased the levels of: (i) global DNA methylation, (ii) 5-methylcytosine, (iii) DNA methyltransferase (DNMT) activity and (iv) messenger RNA (mRNA) and protein levels of DNMT1, DNMT3a and DNMT3b in these cells. Similar effects were noted when these cancer cells were treated identically with 5-aza-2′-deoxycytidine, an inhibitor of DNA methylation. GSPs decreased histone deacetylase activity, increased levels of acetylated lysines 9 and 14 on histone H3 (H3-Lys 9 and 14) and acetylated lysines 5, 12 and 16 on histone H4, and reduced the levels of methylated H3-Lys 9. Further, GSP treatment resulted in re-expression of the mRNA and proteins of silenced tumor suppressor genes, RASSF1A, p16{sup INK4a} and Cip1/p21. Together, this study provides a new insight into the epigenetic mechanisms of GSPs and may have significant implications for epigenetic therapy in the treatment/prevention of skin cancers in humans. -- Highlights: ►Epigenetic modulations have been shown to have a role in cancer risk. ►Proanthocyanidins decrease the levels of DNA methylation and histone deacetylation. ►Proanthocyanidins inhibit histone deacetylase activity in skin cancer cells. ►Proanthocyanidins reactivate tumor suppressor genes in skin

  18. Candidate tumor suppressor and pVHL partner Jade-1 binds and inhibits AKT in renal cell carcinoma.

    PubMed

    Zeng, Liling; Bai, Ming; Mittal, Amit K; El-Jouni, Wassim; Zhou, Jing; Cohen, David M; Zhou, Mina I; Cohen, Herbert T

    2013-09-01

    The von Hippel-Lindau (VHL) tumor suppressor pVHL is lost in the majority of clear-cell renal cell carcinomas (RCC). Activation of the PI3K/AKT/mTOR pathway is also common in RCC, with PTEN loss occurring in approximately 30% of the cases, but other mechanisms responsible for activating AKT at a wider level in this setting are undefined. Plant homeodomain protein Jade-1 (PHF17) is a candidate renal tumor suppressor stabilized by pVHL. Here, using kinase arrays, we identified phospho-AKT1 as an important target of Jade-1. Overexpressing or silencing Jade-1 in RCC cells increased or decreased levels of endogenous phospho-AKT/AKT1. Furthermore, reintroducing pVHL into RCC cells increased endogenous Jade-1 and suppressed endogenous levels of phospho-AKT, which colocalized with and bound to Jade-1. The N-terminus of Jade-1 bound both the catalytic domain and the C-terminal regulatory tail of AKT, suggesting a mechanism through which Jade-1 inhibited AKT kinase activity. Intriguingly, RCC precursor cells where Jade-1 was silenced exhibited an increased capacity for AKT-dependent anchorage-independent growth, in support of a tumor suppressor function for Jade-1 in RCC. In support of this concept, an in silico expression analysis suggested that reduced Jade-1 expression is a poor prognostic factor in clear-cell RCC that is associated with activation of an AKT1 target gene signature. Taken together, our results identify 2 mechanisms for Jade-1 fine control of AKT/AKT1 in RCC, through loss of pVHL, which decreases Jade-1 protein, or through attenuation in Jade-1 expression. These findings help explain the pathologic cooperativity in clear-cell RCC between PTEN inactivation and pVHL loss, which leads to decreased Jade-1 levels that superactivate AKT. In addition, they prompt further investigation of Jade-1 as a candidate biomarker and tumor suppressor in clear-cell RCC.

  19. Concomitant deletions of tumor suppressor genes MEN1 and AIP are essential for the pathogenesis of the brown fat tumor hibernoma.

    PubMed

    Nord, Karolin H; Magnusson, Linda; Isaksson, Margareth; Nilsson, Jenny; Lilljebjörn, Henrik; Domanski, Henryk A; Kindblom, Lars-Gunnar; Mandahl, Nils; Mertens, Fredrik

    2010-12-07

    Hibernomas are benign tumors with morphological features resembling brown fat. They consistently display cytogenetic rearrangements, typically translocations, involving chromosome band 11q13. Here we demonstrate that these aberrations are associated with concomitant deletions of AIP and MEN1, tumor suppressor genes that are located 3 Mb apart and that underlie the hereditary syndromes pituitary adenoma predisposition and multiple endocrine neoplasia type I. MEN1 and AIP displayed a low expression in hibernomas whereas the expression of genes up-regulated in brown fat--PPARA, PPARG, PPARGC1A, and UCP1--was high. Thus, loss of MEN1 and AIP is likely to be pathogenetically essential for hibernoma development. Simultaneous loss of two tumor suppressor genes has not previously been shown to result from a neoplasia-associated translocation. Furthermore, in contrast to the prevailing assumption that benign tumors harbor relatively few genetic aberrations, the present analyses demonstrate that a considerable number of chromosome breaks are involved in the pathogenesis of hibernoma.

  20. Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs

    SciTech Connect

    Kurayoshi, Kenta; Ozono, Eiko; Iwanaga, Ritsuko; Bradford, Andrew P.; Komori, Hideyuki; Ohtani, Kiyoshi

    2014-07-18

    Highlights: • ARF promoter showed higher responsiveness to deregulated E2F activity than the E2F1 promoter. • ARF promoter showed higher cancer cell-specificity than E2F1 promoter to drive gene expression. • HSV-TK driven by ARF promoter showed higher cancer cell-specific cytotoxicity than that driven by E2F1 promoter. - Abstract: In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy. In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter

  1. TIMP-2 targets tumor-associated myeloid suppressor cells with effects in cancer immune dysfunction and angiogenesis.

    PubMed

    Guedez, Liliana; Jensen-Taubman, Sandra; Bourboulia, Dimitra; Kwityn, Clifford J; Wei, Beiyang; Caterina, John; Stetler-Stevenson, William G

    2012-07-01

    Angiogenesis and inflammation are important therapeutic targets in non-small cell lung cancer (NSCLC). It is well known that proteolysis mediated by matrix metalloproteinases (MMPs) promotes angiogenesis and inflammation in the tumor microenvironment. Here, the effects of the MMP inhibitor TIMP-2 on NSCLC inflammation and angiogenesis were evaluated in TIMP-2-deficient (timp2-/-) mice injected subcutaneously (SC) with Lewis lung carcinoma cells and compared with the effects on tumors in wild-type mice. TIMP-2-deficient mice demonstrated increased tumor growth, enhanced expression of angiogenic marker αvβ3 in tumor and endothelial cells, and significantly higher serum vascular endothelial growth factor-A levels. Tumor-bearing timp2-/- mice showed a significant number of inflammatory cells in their tumors, upregulation of inflammation mediators, nuclear factor-kappaB, and Annexin A1, as well as higher levels of serum interleukin (IL)-6. Phenotypic analysis revealed an increase in myeloid-derived suppressor cell (MDSC) cells (CD11b+ and Gr-1+) that coexpressed vascular-endothelial-growth factor receptor 1 (VEGF-R1) and elevated MMP activation present in tumors and spleens from timp2-/- mice. Furthermore, TIMP-2-deficient tumors upregulated expression of the immunosuppressing genes controlling MDSC growth, IL-10, IL-13, IL-11, and chemokine ligand (CCL-5/RANTES), and decreased interferon-γ and increased CD40L. Moreover, forced TIMP-2 expression in human lung adenocarcinoma A-549 resulted in a significant reduction of MDSCs recruited into tumors, as well as suppression of angiogenesis and tumor growth. The increase in MDSCs has been linked to cancer immunosuppression and angiogenesis. Therefore, this study supports TIMP-2 as a negative regulator of MDSCs with important implications for the immunotherapy and/or antiangiogenic treatment of NSCLC.

  2. Receptor FGFRL1 acts as a tumor suppressor in nude mice when overexpressed in HEK 293 Tet-On cells

    PubMed Central

    Zhuang, Lei; Steinberg, Florian; Trueb, Beat

    2016-01-01

    Fibroblast growth factor receptor-like 1 (FGFRL1) is a transmembrane receptor that interacts with heparin and FGF ligands. In contrast to the classical FGF receptors, FGFR1 to FGFR4, it does not appear to affect cell growth and proliferation. In the present study, an inducible gene expression system was utilized in combination with a xenograft tumor model to investigate the effects of FGFRL1 on cell adhesion and tumor formation. It was determined that recombinant FGFRL1 promotes the adhesion of HEK 293 Tet-On® cells in vitro. Moreover, when such cells are induced to express FGFRL1ΔC they aggregate into huge clusters. If injected into nude mice, the cells form large tumors. Notably, this tumor growth is completely inhibited when the expression of FGFRL1 is induced. The forced expression of FGFRL1 in the tumor tissue may restore contact inhibition, thereby preventing growth of the cells in nude mice. The results of the present study demonstrate that FGFRL1 acts as a tumor suppressor similar to numerous other cell adhesion proteins. It is therefore likely that FGFRL1 functions as a regular cell-cell adhesion protein. PMID:28101211

  3. Host miR155 promotes tumor growth through a myeloid-derived suppressor cell-dependent mechanism.

    PubMed

    Chen, Siqi; Wang, Long; Fan, Jie; Ye, Cong; Dominguez, Donye; Zhang, Yi; Curiel, Tyler J; Fang, Deyu; Kuzel, Timothy M; Zhang, Bin

    2015-02-01

    miR155 is a regulator of immune cell development and function that is generally thought to be immunostimulatory. However, we report here that genetic ablation of miR155 renders mice resistant to chemical carcinogenesis and the growth of several transplanted tumors, suggesting that miR155 functions in immunosuppression and tumor promotion. Host miR155 deficiency promoted overall antitumor immunity despite the finding of defective responses of miR155-deficient dendritic cells and antitumor T cells. Further analysis of immune cell compartments revealed that miR155 regulated the accumulation of functional myeloid-derived suppressive cells (MDSC) in the tumor microenvironment. Specifically, miR155 mediated MDSC suppressor activity through at least two mechanisms, including SOCS1 repression and a reduced ability to license the generation of CD4(+)Foxp3(+) regulatory T cells. Importantly, we demonstrated that miR155 expression was required for MDSC to facilitate tumor growth. Thus, our results revealed a contextual function for miR155 in antitumor immunity, with a role in MDSC support that appears to dominate in tumor-bearing hosts. Overall, the balance of these cellular effects appears to be a root determinant of whether miR155 promotes or inhibits tumor growth.

  4. The milk protein α-casein functions as a tumor suppressor via activation of STAT1 signaling, effectively preventing breast cancer tumor growth and metastasis.

    PubMed

    Bonuccelli, Gloria; Castello-Cros, Remedios; Capozza, Franco; Martinez-Outschoorn, Ubaldo E; Lin, Zhao; Tsirigos, Aristotelis; Xuanmao, Jiao; Whitaker-Menezes, Diana; Howell, Anthony; Lisanti, Michael P; Sotgia, Federica

    2012-11-01

    Here, we identified the milk protein α-casein as a novel suppressor of tumor growth and metastasis. Briefly, Met-1 mammary tumor cells expressing α-casein showed a ~5-fold reduction in tumor growth and a near 10-fold decrease in experimental metastasis. To identify the molecular mechanism(s), we performed genome-wide transcriptional profiling. Interestingly, our results show that α-casein upregulates gene transcripts associated with interferon/STAT1 signaling and downregulates genes associated with "stemness." These findings were validated by immunoblot and FACS analysis, which showed the upregulation and hyperactivation of STAT1 and a decrease in the number of CD44(+) "cancer stem cells." These gene signatures were also able to predict clinical outcome in human breast cancer patients. Thus, we conclude that a lactation-based therapeutic strategy using recombinant α-casein would provide a more natural and non-toxic approach to the development of novel anticancer therapies.

  5. Reverse engineering of TLX oncogenic transcriptional networks identifies RUNX1 as tumor suppressor in T-ALL.

    PubMed

    Della Gatta, Giusy; Palomero, Teresa; Perez-Garcia, Arianne; Ambesi-Impiombato, Alberto; Bansal, Mukesh; Carpenter, Zachary W; De Keersmaecker, Kim; Sole, Xavier; Xu, Luyao; Paietta, Elisabeth; Racevskis, Janis; Wiernik, Peter H; Rowe, Jacob M; Meijerink, Jules P; Califano, Andrea; Ferrando, Adolfo A

    2012-02-26

    The TLX1 and TLX3 transcription factor oncogenes have a key role in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). Here we used reverse engineering of global transcriptional networks to decipher the oncogenic regulatory circuit controlled by TLX1 and TLX3. This systems biology analysis defined T cell leukemia homeobox 1 (TLX1) and TLX3 as master regulators of an oncogenic transcriptional circuit governing T-ALL. Notably, a network structure analysis of this hierarchical network identified RUNX1 as a key mediator of the T-ALL induced by TLX1 and TLX3 and predicted a tumor-suppressor role for RUNX1 in T cell transformation. Consistent with these results, we identified recurrent somatic loss-of-function mutations in RUNX1 in human T-ALL. Overall, these results place TLX1 and TLX3 at the top of an oncogenic transcriptional network controlling leukemia development, show the power of network analyses to identify key elements in the regulatory circuits governing human cancer and identify RUNX1 as a tumor-suppressor gene in T-ALL.

  6. Negative Regulation of the Stability and Tumor Suppressor Function of Fbw7 by the Pin1 Prolyl Isomerase

    PubMed Central

    Min, Sang-Hyun; Lau, Alan W.; Lee, Tae Ho; Inuzuka, Hiroyuki; Wei, Shuo; Huang, Pengyu; Shaik, Shavali; Lee, Daniel Yenhong; Finn, Greg; Balastik, Martin; Chen, Chun-Hau; Luo, Manli; Tron, Adriana E.; DeCaprio, James A.; Zhou, Xiao Zhen; Wei, Wenyi; Lu, Kun Ping

    2012-01-01

    SUMMARY Fbw7 is the substrate recognition component of the SCF (Skp1-Cullin-F-box)-type E3 ligase complex and a well-characterized tumor suppressor that targets numerous oncoproteins for destruction. Genomic deletion or mutation of FBW7 has been frequently found in various types of human cancers, however, little is known about the upstream signaling pathway(s) governing Fbw7 stability and cellular functions. Here we report that Fbw7 protein destruction and tumor suppressor function are negatively regulated by the prolyl isomerase Pin1. Pin1 interacts with Fbw7 in a phoshorylation-dependent manner and promotes Fbw7 self-ubiquitination and protein degradation by disrupting Fbw7 dimerization. Consequently, over-expressing Pin1 reduces Fbw7 abundance and suppresses Fbw7’s ability to inhibit proliferation and transformation. By contrast, depletion of Pin1 in cancer cells leads to elevated Fbw7 expression, which subsequently reduces Mcl-1 abundance, sensitizing cancer cells to Taxol. Thus, Pin1-mediated inhibition of Fbw7 contributes to oncogenesis and Pin1 may be a promising drug target for anti-cancer therapy. PMID:22608923

  7. ERK5/BMK1 Is a Novel Target of the Tumor Suppressor VHL: Implication in Clear Cell Renal Carcinoma12

    PubMed Central

    Arias-González, Laura; Moreno-Gimeno, Inmaculada; del Campo, Antonio Rubio; Serrano-Oviedo, Leticia; Valero, María Llanos; Esparís-Ogando, Azucena; de la Cruz-Morcillo, Miguel Ángel; Melgar-Rojas, Pedro; García-Cano, Jesús; Cimas, Francisco José; Hidalgo, María José Ruiz; Prado, Alfonso; Callejas-Valera, Juan Luis; Nam-Cha, Syong Hyun; Giménez-Bachs, José Miguel; Salinas-Sánchez, Antonio S; Pandiella, Atanasio; del Peso, Luis; Sánchez-Prieto, Ricardo

    2013-01-01

    Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well as the study of endogenous ERK5 in different experimental systems such as MCF7, HMEC, or Caki-2 cell lines. In fact, the specific knockdown of ERK5 in pVHL-negative cell lines promotes a decrease in proliferation and migration, supporting the role of this MAPK in cellular transformation. Furthermore, in a short series of fresh samples from human clear cell renal cell carcinoma, high levels of ERK5 correlate with more aggressive and metastatic stages of the disease. Therefore, our results provide new biochemical data suggesting that ERK5 is a novel target of the tumor suppressor VHL, opening a new field of research on the role of ERK5 in renal carcinomas. PMID:23730213

  8. Secreted frizzled-related protein-5 is epigenetically downregulated and functions as a tumor suppressor in kidney cancer.

    PubMed

    Kawakami, Kazumori; Yamamura, Soichiro; Hirata, Hiroshi; Ueno, Koji; Saini, Sharanjot; Majid, Shahana; Tanaka, Yuichiro; Kawamoto, Ken; Enokida, Hideki; Nakagawa, Masayuki; Dahiya, Rajvir

    2011-02-01

    Secreted frizzled-related protein-5 (sFRP-5) has been identified as 1 of the secreted antagonists that bind Wnt protein. However, the functional significance of sFRP-5 in renal cell cancer (RCC) has not been reported. We hypothesized that sFRP-5 may be epigenetically downregulated through DNA methylation and histone modification and function as a tumor suppressor gene in RCC. Using tissue microarray and real-time RT-PCR, we found that sFRP-5 was significantly downregulated in kidney cancer tissues and cell lines, respectively. DNA bisulfite sequencing of the sFRP-5 promoter region in RCC cell lines showed it to be densely methylated, whereas there was few promoter methylation in normal kidney. The sFRP-5 expression was restored and the acetylation of H3 and H4 histones associated with the sFRP-5 promoter region were significantly increased after treatment with demethylation agent (5-Aza-dc) and histone deacetylase inhibitor (TSA). When RCC cells were transfected with the sFRP-5 gene, significant inhibition of anchorage independent colony formation and cell invasion were observed compared to controls. The sFRP-5 transfection also significantly induced apoptosis in RCC cells. In conclusion, this is the first report documenting that the sFRP-5 is downregulated by promoter methylation and histone acetylation and functions as a tumor suppressor gene by inducing apoptosis in RCC cells.

  9. Rapid asymmetric evolution of a dual-coding tumor suppressor INK4a/ARF locus contradicts its function

    PubMed Central

    Szklarczyk, Radek; Heringa, Jaap; Pond, Sergei Kosakovsky; Nekrutenko, Anton

    2007-01-01

    INK4a/ARF tumor suppressor locus encodes two protein products, INK4a and ARF, essential for controlling tumorigenesis and mutated in more than half of human cancers. There is no resemblance between the two proteins: their coding regions are assembled by alternative splicing of two mutually exclusive 5′ exons into a constitutive one containing overlapping out-of-phase reading frames. We show that the dual-coding arrangement conflicts with the high cost of mutations within INK4a/ARF. Unexpectedly, the locus evolves rapidly and asymmetrically, with ARF accumulating the majority of amino acid replacements. Rapid evolution drives both INK4a and ARF proteins out of sync with other members of the RB and p53 tumor suppressor pathways, both of which are controlled by the locus. Yet, the asymmetric behavior may be an intrinsic property of dual-coding exons: INK4a/ARF closely mimics the evolution of 90 newly identified genes with similar dual-coding structure. Thus, the strong link between mutations in INK4a/ARF and cancer may be a direct consequence of the architecture of the locus. PMID:17652172

  10. A defined chromosome 6q fragment (at D6S310) harbors a putative tumor suppressor gene for breast cancer.

    PubMed

    Theile, M; Seitz, S; Arnold, W; Jandrig, B; Frege, R; Schlag, P M; Haensch, W; Guski, H; Winzer, K J; Barrett, J C; Scherneck, S

    1996-08-15

    Recent evidence obtained by cytogenetic and molecular studies indicates that in breast cancer chromosome 6q is often affected by genetic changes suggesting the existence of putative tumor suppressor genes (TSGs). However the function of gene(s) on this chromosome in breast cancer suppression is not understood. To substantiate further the presence of breast cancer related TSGs at 6q and to define their location, we first performed microcell-mediated transfer of chromosome 6 to CAL51 breast cancer cells for studying possible suppression of malignant phenotype and secondly, we analysed DNAs from 46 primary breast cancers for loss of constitutive heterozygosity (LOH) using 24 poly-morphic microsatellite markers. The chromosome transfer resulted in loss of tumorigenicity and reversion of other neoplastic properties of the microcell hybrids. Polymorphism analysis of single hybrids revealed that they harbored only a small donor chromosome fragment defined by the marker D6S310 (6q23.3-q25) and flanked by D6S292 and D6S311. The LOH data suggest that four tumor suppressor gene loci mapped to the central and distal portion of 6q may be independently deleted in breast cancer. One of these regions corresponds to the region identified by chromosome transfer.

  11. Simultaneous haploinsufficiency of Pten and Trp53 tumor suppressor genes accelerates tumorigenesis in a mouse model of prostate cancer

    PubMed Central

    Couto, Suzana S.; Cao, Mei; Duarte, Paulo C.; Banach-Petrosky, Whitney; Wang, Shunyou; Romanienko, Peter; Wu, Hong; Cardiff, Robert D.; Abate-Shen, Cory; Cunha, Gerald R.

    2010-01-01

    Tumor suppressor gene PTEN is important in the initiation and progression of human prostate carcinoma, whereas the role of TP53 remains controversial. Since Pten/Trp53 double conditional knockout mice show earlier onset and fast progression of prostate cancer when compared to Pten knockout mice, we asked whether heterozygosity of these two tumor suppressor genes was sufficient to accelerate prostatic tumorigenesis. To answer this question we examined prostatic lesion progression of Pten/Trp53 double heterozygous mice and a series of controls such as Pten heterozygous, Pten conditional knockout, Trp53 heterozygous and Trp53 knockout mice. Tissue recombination of adult prostatic epithelium coupled with embryonic rat seminal vesicle mesenchyme was used as a tool to stimulate prostatic epithelial proliferation. In our study, high-grade prostatic intraepithelial neoplasia (PIN) was found with high frequency at 8 weeks post-tissue recombination transplantation. PIN lesions in Pten/Trp53 double heterozygous mice were more severe than those seen in Pten heterozygous alone. Furthermore, morphologic features attributable to Pten or Trp53 loss appeared to be enhanced in double heterozygous tissues. LOH analysis of Pten and Trp53 in genomic DNA collected from high-grade PIN lesions in Pten heterozygous and Pten/Trp53 double heterozygous mice showed an intact wild-type allele for both genes in all samples examined. In conclusion, simultaneous heterozygosity of Pten and Trp53 accelerates prostatic tumorigenesis in this mouse model of prostate cancer independently of loss of heterozygosity of either gene. PMID:19281769

  12. Correlation between myeloid-derived suppressor cells and S100A8/A9 in tumor and autoimmune diseases.

    PubMed

    Zheng, Ruoting; Chen, Shiyi; Chen, Shenren

    2015-12-01

    Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that constitute an important component of immune regulatory system. Two calcium-binding proteins S100A8 and S100A9 act as important mediators in acute and chronic inflammation. In recent years, many researchers have found that MDSCs and S100A8/A9 operated with one another through a positive feedback loop to promote tumor development and metastasis. However, the correlation between MDSCs and S100A8/A9 in autoimmune diseases (AIDs) remains unknown. In this review, we discussed the co-operation of MDSCs and S100A8/A9 in tumor environment, and also, the role of these two components in AIDs.

  13. Salmonella-mediated tumor regression involves targeting of tumor myeloid suppressor cells causing a shift to M1-like phenotype and reduction in suppressive capacity.

    PubMed

    Kaimala, Suneesh; Mohamed, Yassir A; Nader, Nancy; Issac, Jincy; Elkord, Eyad; Chouaib, Salem; Fernandez-Cabezudo, Maria J; Al-Ramadi, Basel K

    2014-06-01

    The effectiveness of attenuated Salmonella in inhibiting tumor growth has been demonstrated in many therapeutic models, but the precise mechanisms remain incompletely understood. In this study, we show that the anti-tumor capacity of Salmonella depends on a functional MyD88-TLR pathway and is independent of adaptive immune responses. Since myeloid suppressor cells play a critical role in tumor growth, we investigated the consequences of Salmonella treatment on myeloid cell recruitment, phenotypic characteristics, and functional activation in spleen and tumor tissue of B16.F1 melanoma-bearing mice. Salmonella treatment led to increased accumulation of splenic and intratumoral CD11b(+)Gr-1(+) myeloid cells, exhibiting significantly increased expression of various activation markers such as MHC class II, costimulatory molecules, and Sca-1/Ly6A proteins. Gene expression analysis showed that Salmonella treatment induced expression of iNOS, arginase-1 (ARG1), and IFN-γ in the spleen, but down-regulated IL-4 and TGF-β. Within the tumor, expression of iNOS, IFN-γ, and S100A9 was markedly increased, but ARG1, IL-4, TGF-β, and VEGF were inhibited. Functionally, splenic CD11b(+) cells maintained their suppressive capacity following Salmonella treatment, but intratumoral myeloid cells had significantly reduced suppressive capacity. Our findings demonstrate that administration of attenuated Salmonella leads to phenotypic and functional maturation of intratumoral myeloid cells making them less suppressive and hence enhancing the host's anti-tumor immune response. Modalities that inhibit myeloid suppressor cells may be useful adjuncts in cancer immunotherapy.

  14. TUMORAL TISSUE SPECIFIC PROMOTER HYPERMETHYLATION OF DISTINCT TUMOR SUPPRESSOR GENES IN A CASE WITH NONSMALL CELL LUNG CARCINOMA: A CASE REPORT

    PubMed Central

    Arslan, Sulhattin; Dogan, Tamer; Koksal, Binnur; Yildirim, Malik Ejder; Gumus, Cesur; Elagoz, Sahenda; Akkurt, Ibrahim; Ozdemir, Oztürk

    2008-01-01

    SUMMARY Objective: Non-small cell lung carcinoma is an aggressive phenomenon and the epigenetical alterations of some tumor supressor genes have been reported for the different tumor types. Case Presentation: It is presented a case report concerning a 43 years old male with NSCLC on the lower segment of the right lung. The patient underwent a diag-nostic excisional thin-needle biopsy and after the histological confirmation. We examined the promoter methylation status of some distinct tumor supressor genes in tumoral and blood tissues of the case after sodium bisulfite conversion and DNA amplification with methylation specific multiplex PCR technique. Both tissues were also searched for G to A transitions in codons 12 and 13 of the K-ras proto-oncogene. Results: Tumor specimen showed fully methyl pattern profiles for the SFRP2, p16, DAPK1 and partially hyper-methylated profile for the p53 and MGMT genes in this case with non-small lung carci-noma. Blood speicemen showed normal hypomethylated profiles for all studied TS genes. The K-ras proto-oncogene was in normal structure both in blood and tumoral spiecemens that examined. Conclusion: Results indicate that genes exhibit tumor suppressor activi-ties in blood, but exhibit epigenetic inactivation in carcinoma cell. These findings strongly support the hypothesis that epigenetic mechanisms may play an important role in the non-small cell lung carcinogenesis in human. PMID:21264081

  15. Molecular analysis of the fragile histidine triad (FHIT) tumor suppressor gene in vesical tumors of cattle with chronic enzootic hematuria (CEH).

    PubMed

    Guidi, E; Uboldi, C; Ferretti, L

    2008-01-01

    The FHIT (fragile histidine triad) gene is a tumor suppressor gene known to be inactivated in many tumors including bladder tumors and is spanning FRA3B, a very active common fragile site in the human genome. We have recently isolated the bovine gene, and the aim of this study was to test whether FHIT presents altered expression patterns in vesical tumors of cattle with CEH (chronic enzootic hematuria). CEH is a common syndrome affecting Mediterranean cattle: clastogenic, mutagenic and cancerogenic substances released by the bracken fern (Pteridium spp) grazed by animals induce the formation of neoplastic lesions, among which bladder tumors have a high incidence. We analysed FHIT in 23 bladder tumors of CEH cattle looking at: 1) the methylation status of the CpG island comprising the promoter and part of exon 1; 2) the presence of altered FHIT transcripts; 3) the mRNA expression levels measured with a quantitative real time PCR (QRT-PCR) approach. Our results suggest that unlike in human tumors, FHIT in vesical tumors of CEH cattle is largely unmethylated. Furthermore, the same mRNA isoforms of FHIT were detected in tumors and in healthy tissues, including a novel isoform that was found in this study. Finally, QRT-PCR data did not reveal significantly altered expression profiles of FHIT transcripts. Further studies and larger sets of cases will be useful to confirm this finding, but the data seem to suggest that epigenetic modifications of FHIT and altered expression profiles are not a hallmark of bovine vesical tumors like they are in human tumors.

  16. Genetic analysis of tumorigenesis: a conserved region in the human and Chinese hamster genomes contains genetically identified tumor-suppressor genes

    SciTech Connect

    Stenman, G.; Sager, R.

    1987-12-01

    Regional chromosome homologies were found in a comparison of human 11p with Chinese hamster 3p. By use of probes that recognize six genes of human 11p (INS, CAT, HBBC, CALC, PTH, and HRAS), the corresponding genes were localized by in situ hybridization on Chinese hamster chromosome 3. INS and CAT were located close to the centromere on 3p, whereas HBBC, CALC, and PTH were at 3q3-4 and HRAS at 3q4. Extensive prior data from chromosome studies of tumorigenic and tumor-derived Chinese hamster cells have suggested the presence of a tumor-suppressor gene on 3p. Two tumor-suppressor genes have been described on human 11p, one linked to CAT and one to INS. The present study raises the possibility that the Chinese hamster suppressor may be closely linked to INS or CAT.

  17. Altered RNA editing in 3′ UTR perturbs microRNA-mediated regulation of oncogenes and tumor-suppressors

    PubMed Central

    Zhang, Liye; Yang, Chih-Sheng; Varelas, Xaralabos; Monti, Stefano

    2016-01-01

    RNA editing is a molecular event that alters specific nucleotides in RNA post-transcriptionally. RNA editing has the potential to impact a variety of cellular processes and is implicated in diseases such as cancer. Yet, the precise mechanisms by which RNA editing controls cellular processes are poorly understood. Here, we characterize sequences altered by RNA editing in patient samples from lymphoma, neuroblastoma and head and neck cancers. We show that A-to-I RNA editing sites are highly conserved across samples of the same tissue type and that most editing sites identified in tumors are also detectable in normal tissues. Next, we identify the significant changes in editing levels of known sites between tumor and paired “normal” tissues across 14 cancer types (627 pairs) from The Cancer Genome Atlas project and show that the complexity of RNA editing regulation cannot be captured by the activity of ADAR family genes alone. Our pan-cancer analysis confirms previous results on individual tumor types and suggests that changes of RNA editing levels in coding and 3′UTR regions could be a general mechanism to promote tumor growth. We also propose a model explaining how altered RNA editing levels affect microRNA-mediated post-transcriptional regulation of oncogenes and tumor-suppressors. PMID:26980570

  18. TRIM14 is a Putative Tumor Suppressor and Regulator of Innate Immune Response in Non-Small Cell Lung Cancer

    PubMed Central

    Hai, Josephine; Zhu, Chang-Qi; Wang, Tao; Organ, Shawna L.; Shepherd, Frances A.; Tsao, Ming-Sound

    2017-01-01

    Non-small-cell lung carcinoma (NSCLC) accounts for 85% of malignant lung tumors and is the leading cause of cancer deaths. Our group previously identified Tripartite Motif 14 (TRIM14) as a component of a prognostic multigene expression signature for NSCLC. Little is known about the function of TRIM14 protein in normal or disease states. We investigated the functional and prognostic role of TRIM14 in NSCLC using in vitro and in vivo perturbation model systems. Firstly, a pooled RNAi screen identified TRIM14 to effect cell proliferation/survival in NSCLC cells. Secondly, silencing of TRIM14 expression significantly enhanced tumor growth in NSCLC xenograft mouse models, while exogenous TRIM14 expression attenuated tumorigenesis. In addition, differences in apoptotic activity between TRIM14-deficient and control tumors suggests that TRIM14 tumor suppressor activity may depend on cell death signaling pathways. TRIM14-deficient cell lines showed both resistance to hypoxia-induced cell death and attenuation of interferon response via STAT1 signaling. Consistent with these phenotypes, multivariate analyses on published mRNA expression datasets of over 600 primary NSCLCs demonstrated that low TRIM14 mRNA levels are significantly associated with poorer prognosis in early stage NSCLC patients. Our functional data therefore establish a novel tumor suppressive role for TRIM14 in NSCLC progression. PMID:28059079

  19. MiR-205 functions as a tumor suppressor in adenocarcinoma and an oncogene in squamous cell carcinoma of esophagus.

    PubMed

    Hezova, Renata; Kovarikova, Alena; Srovnal, Josef; Zemanova, Milada; Harustiak, Tomas; Ehrmann, Jiri; Hajduch, Marian; Sachlova, Milana; Svoboda, Marek; Slaby, Ondrej

    2016-06-01

    Esophageal cancer is a malignant disease with poor prognosis, increasing incidence, and ineffective treatment options. MicroRNAs are post-transcriptional regulators of gene expression involved in many biological processes including carcinogenesis. We determined miR-205 expression levels in tumor/non-tumor tissues of 45 esophageal cancer patients using qPCR and found that decreased level of miR-205 in tumor tissue correlates with poor overall survival in esophageal adenocarcinoma patients. Further, we observed significantly higher levels of miR-205 in tumor tissue of esophageal squamous cell carcinoma. Ectopic overexpression of miR-205 in adenocarcinoma cell line SK-GT-4 led to decreased cell proliferation, cell cycle arrest in G1, and decreased migration ability. Conversely, in squamous cell line KYSE-150, same effects like inhibition of proliferation, migration, and colony-forming potential and cell cycle arrest in G2 were observed after silencing of miR-205. We performed global gene expression profiling and revealed that suppressive functioning of miR-205 in adenocarcinoma could be realized through regulation of epithelial-mesenchymal transition (EMT), whereas oncogenic in squamous cell carcinoma by regulation of metalloproteinase 10. Our results suggest that miR-205 could serve as biomarker in esophageal cancer and acts as a tumor suppressor in esophageal adenocarcinoma and oncogene in esophageal squamous cell carcinoma.

  20. Altered RNA editing in 3' UTR perturbs microRNA-mediated regulation of oncogenes and tumor-suppressors.

    PubMed

    Zhang, Liye; Yang, Chih-Sheng; Varelas, Xaralabos; Monti, Stefano

    2016-03-16

    RNA editing is a molecular event that alters specific nucleotides in RNA post-transcriptionally. RNA editing has the potential to impact a variety of cellular processes and is implicated in diseases such as cancer. Yet, the precise mechanisms by which RNA editing controls cellular processes are poorly understood. Here, we characterize sequences altered by RNA editing in patient samples from lymphoma, neuroblastoma and head and neck cancers. We show that A-to-I RNA editing sites are highly conserved across samples of the same tissue type and that most editing sites identified in tumors are also detectable in normal tissues. Next, we identify the significant changes in editing levels of known sites between tumor and paired "normal" tissues across 14 cancer types (627 pairs) from The Cancer Genome Atlas project and show that the complexity of RNA editing regulation cannot be captured by the activity of ADAR family genes alone. Our pan-cancer analysis confirms previous results on individual tumor types and suggests that changes of RNA editing levels in coding and 3'UTR regions could be a general mechanism to promote tumor growth. We also propose a model explaining how altered RNA editing levels affect microRNA-mediated post-transcriptional regulation of oncogenes and tumor-suppressors.

  1. The hedgehog's trick for escaping immunosurveillance: The molecular mechanisms driving myeloid-derived suppressor cell recruitment in hedgehog signaling-dependent tumors.

    PubMed

    Xie, Jingwu

    2014-01-01

    Myeloid-derived suppressor cells (MDSCs) are an important means by which tumor cells evade immunosurveillance. Here, we set out to determine how MDSCs are recruited to tumors in genetically engineered mouse cancer models. Expression of oncogenic and constitutively active SmoM2, a key hedgehog-signaling regulatory protein, revealed that MDSC recruitment to the tumor microenvironment is mediated by the CCL2/CCR2 axis in a TGFβ dependent fashion.

  2. Promoter methylation status of tumor suppressor genes and inhibition of expression of DNA methyltransferase 1 in non-small cell lung cancer

    PubMed Central

    Liu, Bangqing; Song, Jianfei; Luan, Jiaqiang; Sun, Xiaolin; Bai, Jian; Wang, Haiyong; Li, Angui; Zhang, Lifei; Feng, Xiaoyan

    2016-01-01

    DNA methylation is an epigenetic DNA modification catalyzed by DNA methyltransferase 1 (DNMT1). The purpose of this study was to investigate DNMT1 gene and protein expression and the effects of methylation status on tumor suppressor genes in human non-small cell lung cancer (NSCLC) cell lines grown in vitro and in vivo. Human lung adenocarcinoma cell lines, A549 and H838, were grown in vitro and inoculated subcutaneously into nude mice to form tumors and were then treated with the DNA methylation inhibitor, 5-aza-2′-deoxycytidine, with and without treatment with the benzamide histone deacetylase inhibitor, entinostat (MS-275). DNMT1 protein expression was quantified by Western blot. Promoter methylation status of tumor suppressor genes (RASSF1A, ASC, APC, MGMT, CDH13, DAPK, ECAD, P16, and GATA4) was evaluated by methylation-specific polymerase chain reaction. Methylation status of the tumor suppressor genes was regulated by the DNMT1 gene, with the decrease of DNMT1 expression following DNA methylation treatment. Demethylation of tumor suppressor genes (APC, ASC, and RASSF1A) restored tumor growth in nude mice. The results of this study support a role for methylation of DNA as a potential epigenetic clinical biomarker of prognosis or response to therapy and for DNMT1 as a potential therapeutic target in NSCLC. PMID:27190263

  3. Cross-talk among myeloid-derived suppressor cells, macrophages, and tumor cells impacts the inflammatory milieu of solid tumors

    PubMed Central

    Beury, Daniel W.; Parker, Katherine H.; Nyandjo, Maeva; Sinha, Pratima; Carter, Kayla A.; Ostrand-Rosenberg, Suzanne

    2014-01-01

    MDSC and macrophages are present in most solid tumors and are important drivers of immune suppression and inflammation. It is established that cross-talk between MDSC and macrophages impacts anti-tumor immunity; however, interactions between tumor cells and MDSC or macrophages are less well studied. To examine potential interactions between these cells, we studied the impact of MDSC, macrophages, and four murine tumor cell lines on each other, both in vitro and in vivo. We focused on IL-6, IL-10, IL-12, TNF-α, and NO, as these molecules are produced by macrophages, MDSC, and many tumor cells; are present in most solid tumors; and regulate inflammation. In vitro studies demonstrated that MDSC-produced IL-10 decreased macrophage IL-6 and TNF-α and increased NO. IL-6 indirectly regulated MDSC IL-10. Tumor cells increased MDSC IL-6 and vice versa. Tumor cells also increased macrophage IL-6 and NO and decreased macrophage TNF-α. Tumor cell-driven macrophage IL-6 was reduced by MDSC, and tumor cells and MDSC enhanced macrophage NO. In vivo analysis of solid tumors identified IL-6 and IL-10 as the dominant cytokines and demonstrated that these molecules were produced predominantly by stromal cells. These results suggest that inflammation within solid tumors is regulated by the ratio of tumor cells to MDSC and macrophages and that interactions of these cells have the potential to alter significantly the inflammatory milieu within the tumor microenvironment. PMID:25170116

  4. Putative tumor suppressor loci at 6q22 and 6q23-q24 are involved in the malignant progression of sporadic endocrine pancreatic tumors.

    PubMed

    Barghorn, A; Speel, E J; Farspour, B; Saremaslani, P; Schmid, S; Perren, A; Roth, J; Heitz, P U; Komminoth, P

    2001-06-01

    Our previous comparative genomic hybridization study on sporadic endocrine pancreatic tumors (EPTs) revealed frequent losses on chromosomes 11q, 3p, and 6q. The aim of this study was to evaluate the importance of 6q losses in the oncogenesis of sporadic EPTs and to narrow down the smallest regions of allelic deletion. A multimodal approach combining polymerase chain reaction-based allelotyping, double-target fluorescence in situ hybridization, and comparative genomic hybridization was used in a collection of 109 sporadic EPTs from 93 patients. Nine polymorphic microsatellite markers (6q13 to 6q25-q27) were investigated, demonstrating a loss of heterozygosity (LOH) in 62.2% of the patients. A LOH was significantly more common in tumors >2 cm in diameter than below this threshold as well as in malignant than in benign tumors. We were able to narrow down the smallest regions of allelic deletion at 6q22.1 (D6S262) and 6q23-q24 (D6S310-UTRN) with LOH-frequencies of 50.0% and 41.2 to 56.3%, respectively. Several promising tumor suppressor candidates are located in these regions. Additional fluorescence in situ hybridization analysis on 46 EPTs using three locus-specific probes (6q21, 6q22, and 6q27) as well as a centromere 6-specific probe revealed complete loss of chromosome 6 especially in metastatic disease. We conclude that the two hot spots found on 6q may harbor putative tumor suppressor genes involved not only in the oncogenesis but maybe also in the malignant and metastatic progression of sporadic EPTs.

  5. Caveolin-1 and mitochondrial SOD2 (MnSOD) function as tumor suppressors in the stromal microenvironment

    PubMed Central

    Trimmer, Casey; Sotgia, Federica; Whitaker-Menezes, Diana; Balliet, Renee M; Eaton, Gregory; Martinez-Outschoorn, Ubaldo E; Pavlides, Stephanos; Howell, Anthony; Iozzo, Renato V; Pestell, Richard G; Scherer, Philipp E

    2011-01-01

    Cancer”. The human Cav-1 deficient fibroblasts that we have generated are a new genetically tractable model system for identifying other suppressors of the cancer-associated fibroblast phenotype, via a genetic “complementation” approach. This has important implications for understanding the pathogenesis of triple negative and basal breasts cancers, as well as tamoxifen-resistance in ER-positive breast cancers, which are all associated with a Cav-1 deficient “lethal” tumor microenvironment, driving poor clinical outcome. PMID:21150282

  6. Tumor-derived G-CSF facilitates neoplastic growth through a granulocytic myeloid-derived suppressor cell-dependent mechanism.

    PubMed

    Waight, Jeremy D; Hu, Qiang; Miller, Austin; Liu, Song; Abrams, Scott I

    2011-01-01

    Myeloid-derived suppressor cells (MDSC) are induced under diverse pathologic conditions, including neoplasia, and suppress innate and adaptive immunity. While the mechanisms by which MDSC mediate immunosuppression are well-characterized, details on how they develop remain less understood. This is complicated further by the fact that MDSC comprise multiple myeloid cell types, namely monocytes and granulocytes, reflecting diverse stages of differentiation and the proportion of these subpopulations vary among different neoplastic models. Thus, it is thought that the type and quantities of inflammatory mediators generated during neoplasia dictate the composition of the resultant MDSC response. Although much interest has been devoted to monocytic MDSC biology, a fundamental gap remains in our understanding of the derivation of granulocytic MDSC. In settings of heightened granulocytic MDSC responses, we hypothesized that inappropriate production of G-CSF is a key initiator of granulocytic MDSC accumulation. We observed abundant amounts of G-CSF in vivo, which correlated with robust granulocytic MDSC responses in multiple tumor models. Using G-CSF loss- and gain-of-function approaches, we demonstrated for the first time that: 1) abrogating G-CSF production significantly diminished granulocytic MDSC accumulation and tumor growth; 2) ectopically over-expressing G-CSF in G-CSF-negative tumors significantly augmented granulocytic MDSC accumulation and tumor growth; and 3) treatment of naïve healthy mice with recombinant G-CSF protein elicited granulocytic-like MDSC remarkably similar to those induced under tumor-bearing conditions. Collectively, we demonstrated that tumor-derived G-CSF enhances tumor growth through granulocytic MDSC-dependent mechanisms. These findings provide us with novel insights into MDSC subset development and potentially new biomarkers or targets for cancer therapy.

  7. The Role of Myeloid-Derived Suppressor Cells in Patients with Solid Tumors: A Meta-Analysis

    PubMed Central

    Liu, Li; Wang, Guoping; Yuan, Xia

    2016-01-01

    Targeting immune cells or factors are effective for patients with solid tumors. Myeloid-derived suppressor cells (MDSCs) are known to have immunosuppressive functions, and the levels of MDSCs in patients with solid tumor are assumed to have prognostic values. This meta-analysis aimed at evaluating the relationship between MDSCs and the prognosis of patients with solid tumors. We searched articles in PUBMED and EMBASE comprehensively, updated to March 2016. Eight studies with 442 patients were included in the meta-analysis. We analyzed pooled hazard ratios (HRs) for overall survival (OS), disease-free survival (DFS) and progression-free survival (PFS). The results showed that MDSCs were associated with poor OS (HR, 1.94; 95% confidence interval [CI], 1.42–2.66; P < 0.0001) in patients with solid tumors. PFS/RFS (HR, 1.85; 95% CI, 1.16–2.97; P = 0.01) also indicated the association between MDSCs and prognosis. The HRs and 95% CIs for OS in Asian and non-Asian patients were 2.53 (95% CI 1.61–3.42, p < 0.00001) and 1.67 (95% CI 1.14–2.46, p < 0.0001), respectively. We further analyzed the data according to tumor types. The combined HRs and 95% CIs for OS were 1.26 (95% CI 1.10–1.44, p = 0.0003) for gastrointestinal (GI) cancer, 2.59 (95% CI 1.69–3.98, p < 0.0001) for hepatocellular carcinoma (HCC) and 1.86 (95% CI 1.26–2.75, p = 0.002) for other tumor types. In conclusion, MDSCs had a fine prognostic value for OS and PFS/RFS in patients with solid tumors. MDSCs could be used as biomarkers to evaluate prognosis in clinical practice. PMID:27780254

  8. Ras-association domain family 10 acts as a novel tumor suppressor through modulating MMP2 in hepatocarcinoma

    PubMed Central

    Liu, W; Wang, J; Wang, L; Qian, C; Qian, Y; Xuan, H; Zhuo, W; Li, X; Yu, J; Si, J

    2016-01-01

    Ras-Association Domain Family 10 (RASSF10) is the last identified member of the RASSF family. The functional characteristics of this new gene in human cancers remain largely unclear. Here, we examined RASSF10 for the biological functions and related molecular mechanisms in hepatocellular carcinoma (HCC). We found that RASSF10 is expressed in normal human liver tissue, but is silenced or down-regulated in 62.5% (5/8) of HCC cell lines. The mean expression level of RASSF10 was significantly lower in primary HCCs compared with their adjacent normal tissues (P<0.005, n=52). The promoter methylation contributes to the inactivation of RASSF10 as demonstrated by bisulfite genomic sequencing and demethylation treatment analyses. Transgenic expression of RASSF10 in silenced HCC cell lines suppressed cell viability, colony formation and inhibited tumor growth in nude mice (QGY7703, P<0.01; HepG2, P<0.05). Furthermore, RASSF10 was shown to induce the cell accumulation in G1 phase with the increase of p27, as well as the decrease of cyclinD1 and CDK2/CDK4. Over-expression of RASSF10 also inhibited HCC cells migration (P<0.01) or invasion (P<0.05). Adhesion genes array revealed that Matrix Metalloproteinase 2 (MMP2) was a downstream effector of RASSF10. RASSF10 acting as a tumor suppressor to inhibit HCC invasion partially mediated by Focal Adhesion Kinase or p38 MAPK to decrease the accumulation of MMP2. Our study suggests that RASSF10 acts as a tumor suppressor for HCC. PMID:27348267

  9. TRIM26 functions as a novel tumor suppressor of hepatocellular carcinoma and its downregulation contributes to worse prognosis

    SciTech Connect

    Wang, Yi; He, Du; Yang, Liang; Wen, Bo; Dai, Jinfen; Zhang, Qian; Kang, Jian; He, Weiyang; Ding, Qianshan; He, De

    2015-07-31

    Hepatocellular carcinoma (HCC) is the one of the most common malignancies worldwide and its prognosis is extremely poor. Tripartite motif (TRIM) proteins play crucial roles in cancer cell biology but the function of tripartite motif 26 (TRIM26) has not been investigated. We demonstrated that low expression level of TRIM26 in tumor samples was significantly correlated with worse prognosis in HCC patients. We also demonstrated its expression level was associated with several clinicopathologic features such as AFP level and T stage of HCC patients. Furthermore, we validated that TRIM26 was significantly downregulated in HCC tissue compared with normal liver tissue. To further clarify the functional role of TRIM26 in HCC, We confirmed that TRIM26 silencing can promote cancer cell proliferation, colony forming, migration and invasion in vitro with HCC cell lines HepG2 and Bel-7402. Then we utilized bioinformatic tool to predict gene influenced by TRIM26, showing TRIM26 could modulate gene sets about cancer cell metabolism. In conclusion, we proved that TRIM26 is a novel tumor suppressor modulating multiple metabolism-related pathways in HCC. To our best knowledge, this is the first study to investigate the function of TRIM26 in cancer biology. Our findings provide useful insight into the mechanism of HCC origin and progression. Moreover, TRIM26 may represent a novel therapeutic target for HCC. - Highlights: • TRIM26 is down-regulated in liver cancer samples and functions as a novel tumor suppressor. • Down-regulation of TRIM26 is associated with worse prognosis of hepatocellular carcinoma (HCC). • Knockdown of TRIM26 promotes the proliferation and metastasis of HCC cells. • TRIM26 may function in abnormal metabolic progress of HCC.

  10. Localization of HeLa cell tumor-suppressor gene to the long arm of chromosome II.

    PubMed Central

    Misra, B C; Srivatsan, E S

    1989-01-01

    Cytogenetic and molecular genetic analyses of human intraspecific HeLa x fibroblast hybrids have provided evidence for the presence of a tumor-suppressor gene(s) on chromosome 11 of normal cells. In the present study, we have carried out extensive RFLP analysis of various nontumorigenic and tumorigenic hybrids with at least 50 different chromosome 11-specific probes to determine the precise location of this tumor-suppressor gene(s). Two different hybrid systems, (1) microcell hybrids derived by the transfer of a normal chromosome 11 into a tumorigenic HeLa-derived hybrid cell and (2) somatic cell hybrids derived by the fusion of the HeLa (D98OR) cells to a retinoblastoma (Y79) cell line, were particularly informative. The analysis showed that all but one of the nontumorigenic hybrid cell lines contained a complete copy of the normal chromosome 11. This variant hybrid contained a segment of the long arm but had lost the entire short arm of the chromosome. The tumorigenic microcell and somatic cell hybrids had retained the short arm of the chromosome but had lost at least the q13-23 region of the chromosome. Thus, these results showed a perfect correlation between the presence of the long arm of chromosome 11 and the suppression of the tumorigenic phenotype. We conclude therefore that the gene(s) involved in the suppression of the HeLa cell tumors is localized to the long arm (q arm) of chromosome 11. Images Figure 3 Figure 1 Figure 2 Figure 4 Figure 5 PMID:2577469

  11. The NOR1/OSCP1 proteins in cancer: from epigenetic silencing to functional characterization of a novel tumor suppressor

    PubMed Central

    Yi, Mei; Yang, Jianbo; Li, Wenjuan; Li, Xiaoling; Xiong, Wei; McCarthy, James B.; Li, Guiyuan; Xiang, Bo

    2017-01-01

    NOR1 (Oxidored-nitro domain-containing protein 1), also known as OSCP1, was first identified in nasopharyngeal carcinoma (NPC) cells in 2003. NOR1 is evolutionarily conserved among species with its expression is restricted to brain, testis and respiratory epithelial cells. NOR1 was downregulated in NPC and the downregulation associates with poor prognosis. Previous study demonstrated that hypermethylation of NOR1 promoter was observed in NPC and hematological malignancies, which has been believed to be the main epigenetic cause for NOR1 silencing in these cancers. Recently, the NOR1 tumor suppressor status has been fully established. NOR1 inhibited cancer cell growth by disturbing tumor cell energe metabolism. NOR1 also promote tumor cells apoptosis in oxidative stress and hypoxia by inhibition of stress induced autophagy. Moreover, NOR1 suppressed cancer cell epithelial-mesenchymal transition, invasion and metastasis via activation of FOXA1/HDAC2-slug regulatory network. Deciphering the molecular mechanisms underlying NOR1 mediated tumor suppressive role would be helpful to a deeper understanding of carcinogenesis and, furthermore, to the development of new therapeutic approaches. Here we summarize the current knowledge on NOR1 focusing on its expression pattern, epigenetic and genetic association with human cancers and its biological functions. This review will also elucidate the potential application of NOR1/OSCP1 for some human malignancies. PMID:28367242

  12. TCF7L1 Modulates Colorectal Cancer Growth by Inhibiting Expression of the Tumor-Suppressor Gene EPHB3

    PubMed Central

    Murphy, Matthew; Chatterjee, Sujash S.; Jain, Sidharth; Katari, Manpreet; DasGupta, Ramanuj

    2016-01-01

    Dysregulation of the Wnt pathway leading to accumulation of β-catenin (CTNNB1) is a hallmark of colorectal cancer (CRC). Nuclear CTNNB1 acts as a transcriptional coactivator with TCF/LEF transcription factors, promoting expression of a broad set of target genes, some of which promote tumor growth. However, it remains poorly understood how CTNNB1 interacts with different transcription factors in different contexts to promote different outcomes. While some CTNNB1 target genes are oncogenic, others regulate differentiation. Here, we found that TCF7L1, a Wnt pathway repressor, buffers CTNNB1/TCF target gene expression to promote CRC growth. Loss of TCF7L1 impaired growth and colony formation of HCT116 CRC cells and reduced tumor growth in a mouse xenograft model. We identified a group of CTNNB1/TCF target genes that are activated in the absence of TCF7L1, including EPHB3, a marker of Paneth cell differentiation that has also been implicated as a tumor suppressor in CRC. Knockdown of EPHB3 partially restores growth and normal cell cycle progression of TCF7L1-Null cells. These findings suggest that while CTNNB1 accumulation is critical for CRC progression, activation of specific Wnt target genes in certain contexts may in fact inhibit tumor growth. PMID:27333864

  13. Ex vivo generation of myeloid-derived suppressor cells that model the tumor immunosuppressive environment in colorectal cancer

    PubMed Central

    Dufait, Inès; Schwarze, Julia Katharina; Liechtenstein, Therese; Leonard, Wim; Jiang, Heng; Escors, David

    2015-01-01

    Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of cells that accumulate in tumor-bearing subjects and which strongly inhibit anti-cancer immune responses. To study the biology of MDSC in colorectal cancer (CRC), we cultured bone marrow cells in conditioned medium from CT26 cells, which are genetically modified to secrete high levels of granulocyte-macrophage colony-stimulating factor. This resulted in the generation of high numbers of CD11b+ Ly6G+ granulocytic and CD11b+ Ly6C+ monocytic MDSC, which closely resemble those found within the tumor but not the spleen of CT26 tumor-bearing mice. Such MDSC potently inhibited T-cell responses in vitro, a process that could be reversed upon blocking of arginase-1 or inducible nitric oxide synthase (iNOS). We confirmed that inhibition of arginase-1 or iNOS in vivo resulted in the stimulation of cytotoxic T-cell responses. A delay in tumor growth was observed upon functional repression of both enzymes. These data confirm the role of MDSC as inhibitors of T-cell-mediated immune responses in CRC. Moreover, MDSC differentiated in vitro from bone marrow cells using conditioned medium of GM-CSF-secreting CT26 cells, represent a valuable platform to study/identify drugs that counteract MDSC activities. PMID:25869209

  14. SOX15 is a candidate tumor suppressor in pancreatic cancer with a potential role in Wnt/β-catenin signaling.

    PubMed

    Thu, K L; Radulovich, N; Becker-Santos, D D; Pikor, L A; Pusic, A; Lockwood, W W; Lam, W L; Tsao, M-S

    2014-01-16

    Pancreatic cancer is among the top five deadliest cancers in developed countries. Better knowledge of the molecular mechanisms contributing to its tumorigenesis is imperative to improve patient prognosis. Identification of novel tumor suppressor genes (TSGs) in pancreatic cancer will reveal new mechanisms of pathway deregulation and will ultimately help improve our understanding of this aggressive disease. According to Knudson's two-hit model, TSGs are classically disrupted by two concerted genetic events. In this study, we combined DNA methylation profiling with copy number and mRNA expression profiling to identify novel TSGs in a set of 20 pancreatic cancer cell lines. These data sets were integrated for each of ∼12 000 genes in each cell line enabling the elucidation of those genes that undergo DNA hypermethylation, copy-number loss and mRNA downregulation simultaneously in multiple cell lines. Using this integrative genomics strategy, we identified SOX15 (sex determining region Y-box 15) as a candidate TSG in pancreatic cancer. Expression of SOX15 in pancreatic cancer cell lines with undetectable expression resulted in reduced viability of cancer cells both in vitro and in vivo demonstrating its tumor suppressive capability. We also found reduced expression, homozygous deletion and aberrant DNA methylation of SOX15 in clinical pancreatic tumor data sets. Furthermore, we deduced a novel role for SOX15 in suppressing the Wnt/β-catenin signaling pathway, which we hypothesize is a pathway through which SOX15 may exert its tumor suppressive effects in pancreatic cancer.

  15. PHTS, a novel putative tumor suppressor, is involved in the transformation reversion of HeLaHF cells independently of the p53 pathway

    SciTech Connect

    Yu Dehua; Fan, Wufang; Liu, Guohong; Nguy, Vivian; Chatterton, Jon E.; Long Shilong; Ke, Ning; Meyhack, Bernd; Bruengger, Adrian; Brachat, Arndt; Wong-Staal, Flossie; Li, Qi-Xiang . E-mail: li@immusol.com

    2006-04-01

    HeLaHF is a non-transformed revertant of HeLa cells, likely resulting from the activation of a putative tumor suppressor(s). p53 protein was stabilized in this revertant and reactivated for certain transactivation functions. Although p53 stabilization has not conclusively been linked to the reversion, it is clear that the genes in p53 pathway are involved. The present study confirms the direct role of p53 in HeLaHF reversion by demonstrating that RNAi-mediated p53 silencing partially restores anchorage-independent growth potential of the revertant through the suppression of anoikis. In addition, we identified a novel gene, named PHTS, with putative tumor suppressor properties, and showed that this gene is also involved in HeLaHF reversion independently of the p53 pathway. Expression profiling revealed that PHTS is one of the genes that is up-regulated in HeLaHF but not in HeLa. It encodes a putative protein with CD59-like domains. RNAi-mediated PHTS silencing resulted in the partial restoration of transformation (anchorage-independent growth) in HeLaHF cells, similar to that of p53 gene silencing, implying its tumor suppressor effect. However, the observed increased transformation potential by PHTS silencing appears to be due to an increased anchorage-independent proliferation rate rather than suppression of anoikis, unlike the effect of p53 silencing. p53 silencing did not affect PHTS gene expression, and vice versa, suggesting PHTS may function in a new and p53-independent tumor suppressor pathway. Furthermore, over-expression of PHTS in different cancer cell lines, in addition to HeLa, reduces cell growth likely via induced apoptosis, confirming the broad PHTS tumor suppressor properties.

  16. P53 tumor suppressor gene and protein expression is altered in cell lines derived from spontaneous and alpha-radiation-induced canine lung tumors

    SciTech Connect

    Tierney, L.A.; Johnson, N.F.; Lechner, J.F.

    1994-11-01

    Mutations in the p53 tumor suppressor gene are the most frequently occurring gene alterations in malignant human cancers, including lung cancer. In lung cancer, common point mutations within conserved exons of the p53 gene result in a stabilized form of mutant protein which is detectable in most cases by immunohistochemistry. In addition to point mutations, allelic loss, rearrangements, and deletions of the p53 gene have also been detected in both human and rodent tumors. It has been suggested that for at least some epithelial neoplasms, the loss of expression of wild-type p53 protein may be more important for malignant transformation than the acquisition of activating mutations. Mechanisms responsible for the loss of expression of wild-type protein include gene deletion or rearrangement, nonsense or stop mutations, mutations within introns or upstream regulatory regions of the gene, and accelerated rates of degradation of the protein by DNA viral oncoproteins.

  17. Transcriptional Repression of Tumor Suppressor CDC73, Encoding an RNA Polymerase II Interactor, by Wilms Tumor 1 Protein (WT1) Promotes Cell Proliferation

    PubMed Central

    Rather, Mohammad Iqbal; Swamy, Shivananda; Gopinath, Kodaganur S.; Kumar, Arun

    2014-01-01

    The Wilms tumor 1 gene (WT1) can either repress or induce the expression of genes. Inconsistent with its tumor suppressor role, elevated WT1 levels have been observed in leukemia and solid tumors. WT1 has also been suggested to act as an oncogene by inducing the expression of MYC and BCL-2. However, these are only the correlational studies, and no functional study has been performed to date. Consistent with its tumor suppressor role, CDC73 binds to RNA polymerase II as part of a PAF1 transcriptional regulatory complex and causes transcriptional repression of oncogenes MYC and CCND1. It also represses β-catenin-mediated transcription. Based on the reduced level of CDC73 in oral squamous cell carcinoma (OSCC) samples in the absence of loss-of-heterozygosity, promoter methylation, and mutations, we speculated that an inhibitory transcription factor is regulating its expression. The bioinformatics analysis predicted WT1 as an inhibitory transcription factor to regulate the CDC73 level. Our results showed that overexpression of WT1 decreased CDC73 levels and promoted proliferation of OSCC cells. ChIP and EMSA results demonstrated binding of WT1 to the CDC73 promoter. The 5-azacytidine treatment of OSCC cells led to an up-regulation of WT1 with a concomitant down-regulation of CDC73, further suggesting regulation of CDC73 by WT1. Exogenous CDC73 attenuated the protumorigenic activity of WT1 by apoptosis induction. An inverse correlation between expression levels of CDC73 and WT1 was observed in OSCC samples. These observations indicated that WT1 functions as an oncogene by repressing the expression of CDC73 in OSCC. We suggest that targeting WT1 could be a therapeutic strategy for cancer, including OSCC. PMID:24257751

  18. Enzymological analysis of the tumor suppressor A-C1 reveals a novel group of phospholipid-metabolizing enzymes.

    PubMed

    Shinohara, Naoki; Uyama, Toru; Jin, Xing-Hua; Tsuboi, Kazuhito; Tonai, Takeharu; Houchi, Hitoshi; Ueda, Natsuo

    2011-11-01

    A-C1 protein is the product of a tumor suppressor gene negatively regulating the oncogene Ras and belongs to the HRASLS (HRAS-like suppressor) subfamily. We recently found that four members of this subfamily expressed in human tissues function as phospholipid-metabolizing enzymes. Here we examined a possible enzyme activity of A-C1. The homogenates of COS-7 cells overexpressing recombinant A-C1s from human, mouse, and rat showed a phospholipase A½ (PLA½) activity toward phosphatidylcholine (PC). This finding was confirmed with the purified A-C1. The activity was Ca²⁺ independent, and dithiothreitol and Nonidet P-40 were indispensable for full activity. Phosphatidylethanolamine (PE) was also a substrate and the phospholipase A₁ (PLA₁) activity was dominant over the PLA₂ activity. Furthermore, the protein exhibited acyltransferase activities transferring an acyl group of PCs to the amino group of PEs and the hydroxyl group of lyso PCs. As for tissue distribution in human, mouse, and rat, A-C1 mRNA was abundantly expressed in testis, skeletal muscle, brain, and heart. These results demonstrate that A-C1 is a novel phospholipid-metabolizing enzyme. Moreover, the fact that all five members of the HRASLS subfamily, including A-C1, show similar catalytic properties strongly suggests that these proteins constitute a new class of enzymes showing PLA½ and acyltransferase activities.

  19. An in vivo screen identifies ependymoma oncogenes and tumor-suppressor genes

    PubMed Central

    Mohankumar, Kumarasamypet M.; Currle, David S.; White, Elsie; Boulos, Nidal; Dapper, Jason; Eden, Christopher; Nimmervoll, Birgit; Thiruvenkatam, Radhika; Connelly, Michele; Kranenburg, Tanya A.; Neale, Geoffrey; Olsen, Scott; Wang, Yong-Dong; Finkelstein, David; Wright, Karen; Gupta, Kirti; Ellison, David W.; Thomas, Arzu Onar; Gilbertson, Richard J.

    2015-01-01

    Cancers are characterized by non-random, chromosome copy number alterations that presumably contain oncogenes and tumor–suppressor genes (TSGs). The affected loci are often large, making it difficult to pinpoint which genes are driving the cancer. Here, we report a cross-species in vivo screen of 84 candidate oncogenes and 39 candidate TSGs, located within 28 recurrent chromosomal alterations in ependymoma. Through a series of mouse models we validate eight new ependymoma oncogenes and 10 ependymoma TSGs that converge on a small number of cell functions including vesicle trafficking, DNA modification and cholesterol biosynthesis, pinpointing these as potential new therapeutic targets. PMID:26075792

  20. Osteoprotegerin Contributes to the Metastatic Potential of Cells with a Dysfunctional TSC2 Tumor-Suppressor Gene

    PubMed Central

    Steagall, Wendy K.; Pacheco-Rodriguez, Gustavo; Glasgow, Connie G.; Ikeda, Yoshihiko; Lin, Jing-Ping; Zheng, Gang; Moss, Joel

    2014-01-01

    In addition to its effects on bone metabolism, osteoprotegerin (OPG), a soluble member of the tumor necrosis factor family of receptors, promotes smooth muscle cell proliferation and migration and may act as a survival factor for tumor cells. We hypothesized that these cellular mechanisms of OPG may be involved in the growth and proliferation of lymphangioleiomyomatosis (LAM) cells, abnormal smooth muscle-like cells with mutations in one of the tuberous sclerosis complex tumor-suppressor genes (TSC1/TSC2) that cause LAM, a multisystem disease characterized by cystic lung destruction, lymphatic infiltration, and abdominal tumors. Herein, we show that OPG stimulated proliferation of cells cultured from explanted LAM lungs, and selectively induced migration of LAM cells identified by the loss of heterozygosity for TSC2. Consistent with these observations, cells with TSC2 loss of heterozygosity expressed the OPG receptors, receptor activator of NF-κB ligand, syndecan-1, and syndecan-2. LAM lung nodules showed reactivities to antibodies to tumor necrosis factor–related apoptosis-inducing ligand, receptor activator of NF-κB ligand, syndecan-1, and syndecan-2. LAM lung nodules also produced OPG, as shown by expression of OPG mRNA and colocalization of reactivities to anti-OPG and anti-gp100 (HMB45) antibodies in LAM lung nodules. Serum OPG was significantly higher in LAM patients than in normal volunteers. Based on these data, it appears that OPG may have tumor-promoting roles in the pathogenesis of lymphangioleiomyomatosis, perhaps acting as both autocrine and paracrine factors. PMID:23867796

  1. Paving the Road to Tumor Development and Spreading: Myeloid-Derived Suppressor Cells are Ruling the Fate

    PubMed Central

    Meirow, Yaron; Kanterman, Julia; Baniyash, Michal

    2015-01-01

    Cancer development is dependent on intrinsic cellular changes as well as inflammatory factors in the tumor macro and microenvironment. The inflammatory milieu nourishes the tumor and contributes to cancer progression. Numerous studies, including ours, have demonstrated that the tumor microenvironment is immunosuppressive, impairing the anticancer immune responses. Chronic inflammation was identified as the key process responsible for this immunosuppression via induction of immature myeloid-derived suppressor cells (MDSCs). Upon a prolonged immune response, MDSCs are polarized toward immunosuppressive cells meant to control the exacerbated immune response. In cancer, the chronic inflammatory response renders the MDSCs harmful. Polarized MDSCs suppress T-cells and natural killer cells, as well as antigen-presenting cells, abrogating the beneficial immune response. These changes in the immunological milieu could also lead to high frequency of mutations, enhanced cancer cell stemness, and angiogenesis, directly supporting tumor initiation, growth, and spreading. The presence of MDSCs in cancer poses a serious obstacle in a variety of immune-based therapies, which rely on the stimulation of antitumor immune responses. Cumulative data, including our own, suggest that the selection of an appropriate and effective anticancer therapy must take into consideration the host’s immune status as well as tumor-related parameters. Merging biomarkers for immune monitoring into the traditional patient’s categorization and follow-up can provide new predictive and diagnostic tools to the clinical practice. Chronic inflammation and MDSCs could serve as novel targets for therapeutic interventions, which can be combined with conventional cancer treatments such as chemotherapy, radiotherapy, and cancer cell-targeted and immune-based therapies. Intervention in environmental and tumor-specific inflammatory mechanisms will allow better clinical management of cancer toward more efficient

  2. CASC15-S is a tumor suppressor lncRNA at the 6p22 neuroblastoma susceptibility locus

    PubMed Central

    Russell, Mike R.; Penikis, Annalise; Oldridge, Derek A.; Alvarez-Dominguez, Juan R.; McDaniel, Lee; Diamond, Maura; Padovan, Olivia; Raman, Pichai; Li, Yimei; Wei, Jun S.; Zhang, Shile; Gnanchandran, Janahan; Seeger, Robert; Asgharzadeh, Shahab; Khan, Javed; Diskin, Sharon J.; Maris, John M.; Cole, Kristina A.

    2015-01-01

    Chromosome 6p22 was identified recently as a neuroblastoma susceptibility locus, but its mechanistic contributions to tumorigenesis are as yet undefined. Here we report that the most highly significant single nucleotide polymorphism (SNP) associations reside within CASC15, a long non-coding RNA that we define as a tumor suppressor at 6p22. Low-level expression of a short CASC15 isoform (CASC15-S) associated highly with advanced neuroblastoma and poor patient survival. In human neuroblastoma cells, attenuating CASC15-S increased cellular growth and migratory capacity. Gene expression analysis revealed downregulation of neuroblastoma-specific markers in cells with attenuated CASC15-S, with concomitant increases in cell adhesion and extracellular matrix transcripts. Altogether, our results point to CASC15-S as a mediator of neural growth and differentiation, which impacts neuroblastoma initiation and progression. PMID:26100672

  3. Mapping of 22 new ESTs around a tumor suppressor gene and a senescence gene at 6q16-->q21.

    PubMed

    Morelli, C; Cardona, F; Boyle, J M; Negrini, M; Barbanti-Brodano, G

    1997-01-01

    Twenty two expressed sequence tags (ESTs) have been mapped at the border of 6q16-->q21 and at the proximal end of 6q21, a candidate for two tumor suppressor genes and a senescence gene. Use of a translocation and deletion hybrid panel together with a 4-Mb YAC contig allowed us to precisely define the position of the ESTs. Thirteen ESTs were placed within the 4-Mb interval at the proximal portion of 6q21 using a restriction map of the YAC contig, seven ESTs span a 2-Mb region on the 6q16-->q21 border, and two are distal to the contig. Refinement of the localization of these ESTs will provide substantial assistance in identifying new genes within the region 6q16-->q21.

  4. miR-429 functions as a tumor suppressor by targeting FSCN1 in gastric cancer cells

    PubMed Central

    Zhang, Min; Dong, Bing-bin; Lu, Min; Zheng, Mei-juan; Chen, He; Ding, Jing-zhen; Xu, A-Man; Xu, Yuan-hong

    2016-01-01

    It has been previously reported that the deregulation of microRNAs in gastric cancer (GC) was correlated with the progression and prognosis. miR-429, a member of the miR-200 family, was previously shown to play an important role in human carcinomas. Our study shows that miR-429 is significantly downregulated in GC tissues compared with matched nontumor tissues. Overexpression of miR-429 in GC cells suppressed cell proliferation. Fascin-1 (FSCN1) was identified as one of the targets of miR-429 and knockdown of FSCN1 mimics the function of miR-429 overexpression. In conclusion, miR-429 acts as a tumor suppressor by targeting FSCN1, suggesting that miR-429 and FSCN1 can both be potential therapeutic targets of GC. PMID:27042104

  5. Tumor suppressor Nf2/merlin drives Schwann cell changes following electromagnetic field exposure through Hippo-dependent mechanisms

    PubMed Central

    Colciago, A; Melfi, S; Giannotti, G; Bonalume, V; Ballabio, M; Caffino, L; Fumagalli, F; Magnaghi, V

    2015-01-01

    Previous evidence showed mutations of the neurofibromin type 2 gene (Nf2), encoding the tumor suppressor protein merlin, in sporadic and vestibular schwannomas affecting Schwann cells (SCs). Accordingly, efforts have been addressed to identify possible factors, even environmental, that may regulate neurofibromas growth. In this context, we investigated the exposure of SC to an electromagnetic field (EMF), which is an environmental issue modulating biological processes. Here, we show that SC exposed to 50 Hz EMFs changes their morphology, proliferation, migration and myelinating capability. In these cells, merlin is downregulated, leading to activation of two intracellular signaling pathways, ERK/AKT and Hippo. Interestingly, SC changes their phenotype toward a proliferative/migrating state, which in principle may be pathologically relevant for schwannoma development. PMID:27551454

  6. Polycomb genes interact with the tumor suppressor genes hippo and warts in the maintenance of Drosophila sensory neuron dendrites

    PubMed Central

    Parrish, Jay Z.; Emoto, Kazuo; Jan, Lily Yeh; Jan, Yuh Nung

    2007-01-01

    Dendritic fields are important determinants of neuronal function. However, how neurons establish and then maintain their dendritic fields is not well understood. Here we show that Polycomb group (PcG) genes are required for maintenance of complete and nonoverlapping dendritic coverage of the larval body wall by Drosophila class IV dendrite arborization (da) neurons. In esc, Su(z)12, or Pc mutants, dendritic fields are established normally, but class IV neurons display a gradual loss of dendritic coverage, while axons remain normal in appearance, demonstrating that PcG genes are specifically required for dendrite maintenance. Both multiprotein Polycomb repressor complexes (PRCs) involved in transcriptional silencing are implicated in regulation of dendrite arborization in class IV da neurons, likely through regulation of homeobox (Hox) transcription factors. We further show genetic interactions and association between PcG proteins and the tumor suppressor kinase Warts (Wts), providing evidence for their cooperation in multiple developmental processes including dendrite maintenance. PMID:17437999

  7. Regulation of tumor suppressor EAF2 polyubiquitination by ELL1 and SIAH2 in prostate cancer cells.

    PubMed

    Yu, Xinpei; Ai, Junkui; Cai, Liquan; Jing, Yifeng; Wang, Dan; Dong, Jun; Pascal, Laura E; Zhang, Jian; Luo, Rongcheng; Wang, Zhou

    2016-05-17

    RNA Polymerase II Elongation Factor (ELL)-associated factor 2 (EAF2) is a tumor suppressor frequently down-regulated in human prostate cancer. We previously reported that its binding partner ELL1 can enhance EAF2 protein stability and activity. Here we show that EAF2 can be polyubiquitinated and its degradation blocked by proteasome inhibitor. Co-immunoprecipitation detected EAF2 binding to SIAH2, an E3 ligase, and SIAH2 overexpression enhanced polyubiquitination of EAF2. Co-transfection of EAF2 binding partner ELL1 blocked EAF2 ubiquitination, providing a mechanism for EAF2 stabilization. Finally, EAF2K81R mutant, which exhibits reduced polyubiquitination and increased stability, was more potent than wild-type EAF2 in apoptosis induction. These findings suggest that SIAH2 is an E3 ligase for EAF2 polyubiquitination and ELL1 can enhance EAF2 level and function by blocking its polyubiquitination.

  8. Regulation of tumor suppressor EAF2 polyubiquitination by ELL1 and SIAH2 in prostate cancer cells

    PubMed Central

    Yu, Xinpei; Ai, Junkui; Cai, Liquan; Jing, Yifeng; Wang, Dan; Dong, Jun; Pascal, Laura E.; Zhang, Jian; Luo, Rongcheng; Wang, Zhou

    2016-01-01

    RNA Polymerase II Elongation Factor (ELL)-associated factor 2 (EAF2) is a tumor suppressor frequently down-regulated in human prostate cancer. We previously reported that its binding partner ELL1 can enhance EAF2 protein stability and activity. Here we show that EAF2 can be polyubiquitinated and its degradation blocked by proteasome inhibitor. Co-immunoprecipitation detected EAF2 binding to SIAH2, an E3 ligase, and SIAH2 overexpression enhanced polyubiquitination of EAF2. Co-transfection of EAF2 binding partner ELL1 blocked EAF2 ubiquitination, providing a mechanism for EAF2 stabilization. Finally, EAF2K81R mutant, which exhibits reduced polyubiquitination and increased stability, was more potent than wild-type EAF2 in apoptosis induction. These findings suggest that SIAH2 is an E3 ligase for EAF2 polyubiquitination and ELL1 can enhance EAF2 level and function by blocking its polyubiquitination. PMID:27058417

  9. Ubiquitin-specific protease 11 (USP11) functions as a tumor suppressor through deubiquitinating and stabilizing VGLL4 protein

    PubMed Central

    Zhang, Encheng; Shen, Bing; Mu, Xingyu; Qin, Yan; Zhang, Fang; Liu, Yong; Xiao, Jiantao; Zhang, Pingzhao; Wang, Chenji; Tan, Mingyue; Fan, Yu

    2016-01-01

    VGLL4 is a transcriptional repressor that interacts with transcription factors TEADs and inhibits YAP-induced overgrowth and tumorigenesis. VGLL4 protein was dramatically reduced in various types of human cancers. But how VGLL4 protein is post-transcriptional regulated is poorly understood. In this study, we identify deubiquitinating enzyme USP11 as a novel VGLL4 interactor. We reveal that the USP domain of USP11 and the N-terminal region of VGLL4 are required for mutual binding. USP11 controls VGLL4 protein stability by promoting its deubiquitination. Furthermore, our results show that knockdown of USP11 promotes cell growth, migration, and invasion in a YAP-dependent manner. Together, our results suggest that USP11 may exert its tumor suppressor role by modulating VGLL4/YAP-TEADs regulatory loop. PMID:28042509

  10. The effects of turmeric (curcumin) on tumor suppressor protein (p53) and estrogen receptor (ERα) in breast cancer cells

    PubMed Central

    Hallman, Kelly; Aleck, Katie; Dwyer, Brigitte; Lloyd, Victoria; Quigley, Meghan; Sitto, Nada; Siebert, Amy E; Dinda, Sumi

    2017-01-01

    Curcumin (CUR) is a compound that has antibacterial, antiviral, anti-inflammatory, and anticancer properties. In this study, we have analyzed the effects of CUR on the expression of ERα and p53 in the presence of hormones and anti-hormones in breast cancer cells. Cells were cultured in a medium containing charcoal-stripped fetal bovine serum to deplete any endogenous steroids and treated with CUR at varying concentrations or in combination with hormones and anti-hormones. Protein analysis revealed a relative decrease in the levels of p53 and ERα upon treatment with 5–60 µM CUR. In cell proliferation studies, CUR alone caused a 10-fold decrease compared with the treatment with estrogen, which suggests its antiproliferative effects. Delineating the role of CUR in the regulation of p53, ERα, and their mechanisms of action may be important in understanding the influence of CUR on tumor suppressors and hormone receptors in breast cancer. PMID:28331366

  11. The Role of Tumor Metastases Suppressor Gene, Drg-1, in Breast Cancer

    DTIC Science & Technology

    2008-03-01

    women in the US. Because metastatic disease is the major cause of death, it is crucial to understand the mechanism by which tumor cells metastasize to...examine the effect of NDRG1 on tumor metastases in nude mouse model by injecting NDRG1 expressing cells orthotopically as well as intravenously. We will...also examine the expression of the metalloprotease genes at the tumor site in the animals. We first constructed MDA-MB231 cell line which

  12. Cell surface localization and release of the candidate tumor suppressor Ecrg4 from polymorphonuclear cells and monocytes activate macrophages

    PubMed Central

    Baird, Andrew; Coimbra, Raul; Dang, Xitong; Lopez, Nicole; Lee, Jisook; Krzyzaniak, Michael; Winfield, Robert; Potenza, Bruce; Eliceiri, Brian P.

    2012-01-01

    We identified fresh human leukocytes as an abundant source of the candidate epithelial tumor suppressor gene, Ecrg4, an epigenetically regulated gene, which unlike other tumor suppressor genes, encodes an orphan-secreted, ligand-like protein. In human cell lines, Ecrg4 gene expression was low, Ecrg4 protein undetectable, and Ecrg4 promoter hypermethylation high (45–90%) and reversible by the methylation inhibitor 5-AzaC. In contrast, Ecrg4 gene expression in fresh, normal human PBMCs and PMNs was 600–800 times higher than in cultured cell lines, methylation of the Ecrg4 promoter was low (<3%), and protein levels were readily detectable in lysates and on the cell surface. Flow cytometry, immunofluorescent staining, and cell surface biotinylation established that full-length, 14-kDa Ecrg4 was localized on PMN and monocyte cell surfaces, establishing that Ecrg4 is a membrane-anchored protein. LPS treatment induced processing and release of Ecrg4, as detected by flow and immunoblotting, whereas an effect of fMLF treatment on Ecrg4 on the PMN cell surface was detected on the polarized R2 subpopulation of cells. This loss of cell surface Ecrg4 was associated with the detection of intact and processed Ecrg4 in the conditioned media of fresh leukocytes and was shown to be associated with the inflammatory response that follows severe, cutaneous burn injury. Furthermore, incubation of macrophages with a soluble Ecrg4-derived peptide increased the P-p65, suggesting that processing of an intact sentinel Ecrg4 on quiescent circulating leukocytes leads to processing from the cell surface following injury and macrophage activation. PMID:22396620

  13. MicroRNAs 221/222 and Genistein mediated regulation of ARHI tumor suppressor gene in prostate cancer

    PubMed Central

    Chen, Yi; Zaman, Mohd Saif; Deng, Guoren; Majid, Shahana; Saini, Shranjot; Liu, Jan; Tanaka, Yuichiro; Dahiya, Rajvir

    2010-01-01

    INTRODUCTION ARHI, an imprinted tumor suppressor gene, is expressed in normal immortalized prostate epithelial cells, but is dramatically down-regulated in prostate cancer cell lines. Here we investigated the mechanisms of ARHI silencing in prostate cancer through miRNA and genistein mediated pathways. EXPERIMENTAL PROCEDURE We evaluated ARHI mRNA and protein levels by real time PCR and immunostaining of prostate tissue array. Then, ARHI was over-expressed in prostate cancer PC-3 cells followed by functional studies. Finally, miRNA inhibitor studies and dual luciferase pMIR-REPORT assay were performed to prove the direct target of miR-221&222 to ARHI. RESULTS Both ARHI mRNA and protein levels were down regulated in prostate cancer tissues compared to adjacent normal tissues. Over-expression of ARHI can inhibit cell proliferation, colony formation, invasion and induced apoptosis. Further studies on a new mechanism of ARHI down regulation showed a significant inverse relationship between ARHI and miR-221 & 222 which were up-regulated in cancer cell lines. Transfection of miR-221 & 222 inhibitors into PC-3 cells caused a significant induction of ARHI expression. A direct interaction of miR-221 or 222 with a target site on the 3’UTR of ARHI was confirmed by a dual luciferase pMIR-REPORT assay. CONCLUSIONS ARHI is a tumor suppressor gene down regulated in prostate cancer and over-expression of ARHI can inhibit cell proliferation, colony formation and invasion. This study demonstrates for the first time that prostate cancer cells have decreased level of ARHI which could be caused by direct targeting of 3’UTR of ARHI by miR221/222. PMID:21071579

  14. Molecular Characterization of the Tumor Suppressor Candidate 5 Gene: Regulation by PPARg and Identification of TUSC5 Coding Variants in Lean and Obese Humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tumor suppressor candidate 5 (Tusc5) is a cold-regulated gene expressed abundantly in human and rodent white adipose tissue (WAT), rodent brown adipose tissue (BAT), and peripheral afferent neurons. Strong adipocyte expression and our observation of increased expression following peroxisome prolifer...

  15. Targeting ornithine decarboxylase by α-difluoromethylornithine inhibits tumor growth by impairing myeloid-derived suppressor cells

    PubMed Central

    Ye, Cong; Geng, Zhe; Dominguez, Donye; Chen, Siqi; Fan, Jie; Qin, Lei; Long, Alan; Zhang, Yi; Kuzel, Timothy M.; Zhang, Bin

    2015-01-01

    α-difluoromethylornithine (DFMO) is currently used in chemopreventive regimens primarily for its conventional direct anti-carcinogenesis activity. However, little is known about the effect of decarboxylase (ODC) inhibition by DFMO on antitumor immune responses. We showed here that pharmacologic blockade of ODC by DFMO inhibited tumor growth in intact immunocompetent mice, but abrogated in the immunodeficient Rag1−/− mice, suggesting that antitumor effect of DFMO is dependent on the induction of adaptive anti-tumor T cell immune responses. Depletion of CD8+ T cells impeded the tumor-inhibiting advantage of DFMO. Moreover, DFMO treatment enhanced antitumor CD8+ T cell infiltration and IFN-γ production, and augmented the efficacy of adoptive T cell therapy. Importantly, DFMO impaired Gr1+CD11b+ myeloid-derived suppressor cells (MDSCs) suppressive activity through at least two mechanisms, including reducing arginase expression and activity, and inhibiting CD39/CD73-mediated pathway. MDSCs were one primary cellular target of DFMO as indicated by both adoptive transfer and MDSC depletion analyses. Our findings establish a new role of ODC inhibition by DFMO as a viable and effective immunological adjunct in effective cancer treatment, thereby adding to the growing list of chemoimmunotherapeutic applications of these agents. PMID:26663722

  16. Tumor suppressor KAI1 affects integrin {alpha}v{beta}3-mediated ovarian cancer cell adhesion, motility, and proliferation

    SciTech Connect

    Ruseva, Zlatna; Geiger, Pamina Xenia Charlotte; Hutzler, Peter; Kotzsch, Matthias; Luber, Birgit; Schmitt, Manfred; Gross, Eva; Reuning, Ute

    2009-06-10

    The tetraspanin KAI1 had been described as a metastasis suppressor in many different cancer types, a function for which associations of KAI1 with adhesion and signaling receptors of the integrin superfamily likely play a role. In ovarian cancer, integrin {alpha}v{beta}3 correlates with tumor progression and its elevation in vitro provoked enhanced cell adhesion accompanied by significant increases in cell motility and proliferation in the presence of its major ligand vitronectin. In the present study, we characterized integrin {alpha}v{beta}3-mediated tumor biological effects as a function of cellular KAI1 restoration and proved for the first time that KAI1, besides its already known physical crosstalk with {beta}1-integrins, also colocalizes with integrin {alpha}v{beta}3. Functionally, elevated KAI1 levels drastically increased integrin {alpha}v{beta}3/vitronectin-dependent ovarian cancer cell adhesion. Since an intermediate level of cell adhesive strength is required for optimal cell migration, we next studied ovarian cancer cell motility as a function of KAI1 restoration. By time lapse video microscopy, we found impaired integrin {alpha}v{beta}3/vitronectin-mediated cell migration most probably due to strongly enhanced cellular immobilization onto the adhesion-supporting matrix. Moreover, KAI1 reexpression significantly diminished cell proliferation. These data strongly indicate that KAI1 may suppress ovarian cancer progression by inhibiting integrin {alpha}v{beta}3/vitronectin-provoked tumor cell motility and proliferation as important hallmarks of the oncogenic process.

  17. Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor

    SciTech Connect

    Coppé, Jean-Philippe; Patil, Christopher; Rodier, Francis; Sun, Yu; Munoz, Denise; Goldstein, Joshua; Nelson, Peter; Desprez, Pierre-Yves; Campisi, Judith

    2008-10-24

    Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP) developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial-mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL)-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment.

  18. Multiple Components of the VHL Tumor Suppressor Complex Are Frequently Affected by DNA Copy Number Loss in Pheochromocytoma

    PubMed Central

    Rowbotham, David A.; Enfield, Katey S. S.; Martinez, Victor D.; Thu, Kelsie L.; Vucic, Emily A.; Stewart, Greg L.; Bennewith, Kevin L.; Lam, Wan L.

    2014-01-01

    Pheochromocytomas (PCC) are rare tumors that arise in chromaffin tissue of the adrenal gland. PCC are frequently inherited through predisposing mutations in genes such as the von Hippel-Lindau (VHL) tumor suppressor. VHL is part of the VHL elongin BC protein complex that also includes CUL2/5, TCEB1, TCEB2, and RBX1; in normoxic conditions this complex targets hypoxia-inducible factor 1 alpha (HIF1A) for degradation, thus preventing a hypoxic response. VHL inactivation by genetic mechanisms, such as mutation and loss of heterozygosity, inhibits HIF1A degradation, even in the presence of oxygen, and induces a pseudohypoxic response. However, the described <10% VHL mutation rate cannot account for the high frequency of hypoxic response observed. Indeed, little is known about genetic mechanisms disrupting other complex component genes. Here, we show that, in a panel of 171 PCC tumors, 59.6% harbored gene copy number loss (CNL) of at least one complex component. CNL significantly reduced gene expression and was associated with enrichment of gene targets controlled by HIF1. Interestingly, we show that VHL-related renal clear cell carcinoma harbored disruption of VHL alone. Our results indicate that VHL elongin BC protein complex components other than VHL could be important for PCC tumorigenesis and merit further investigation. PMID:25298778

  19. C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

    SciTech Connect

    Guo, Pin; Nie, Quanmin; Lan, Jin; Ge, Jianwei; Qiu, Yongming; Mao, Qing

    2013-11-08

    Highlights: •The c-Myc oncogene directly upregulates miR-26a expression in GBM cells. •ChIP assays demonstrate that c-Myc interacts with the miR-26a promoter. •Luciferase reporter assays show that PTEN is a specific target of miR-26a. •C-Myc–miR-26a suppression of PTEN may regulate the PTEN/AKT pathway. •Overexpression of c-Myc enhances the proliferative capacity of GBM cells. -- Abstract: The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc–miR-26a–PTEN signaling pathway. This may be of clinical relevance.

  20. Multiple Components of the VHL Tumor Suppressor Complex Are Frequently Affected by DNA Copy Number Loss in Pheochromocytoma.

    PubMed

    Rowbotham, David A; Enfield, Katey S S; Martinez, Victor D; Thu, Kelsie L; Vucic, Emily A; Stewart, Greg L; Bennewith, Kevin L; Lam, Wan L

    2014-01-01

    Pheochromocytomas (PCC) are rare tumors that arise in chromaffin tissue of the adrenal gland. PCC are frequently inherited through predisposing mutations in genes such as the von Hippel-Lindau (VHL) tumor suppressor. VHL is part of the VHL elongin BC protein complex that also includes CUL2/5, TCEB1, TCEB2, and RBX1; in normoxic conditions this complex targets hypoxia-inducible factor 1 alpha (HIF1A) for degradation, thus preventing a hypoxic response. VHL inactivation by genetic mechanisms, such as mutation and loss of heterozygosity, inhibits HIF1A degradation, even in the presence of oxygen, and induces a pseudohypoxic response. However, the described <10% VHL mutation rate cannot account for the high frequency of hypoxic response observed. Indeed, little is known about genetic mechanisms disrupting other complex component genes. Here, we show that, in a panel of 171 PCC tumors, 59.6% harbored gene copy number loss (CNL) of at least one complex component. CNL significantly reduced gene expression and was associated with enrichment of gene targets controlled by HIF1. Interestingly, we show that VHL-related renal clear cell carcinoma harbored disruption of VHL alone. Our results indicate that VHL elongin BC protein complex components other than VHL could be important for PCC tumorigenesis and merit further investigation.

  1. Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor

    PubMed Central

    Coppé, Jean-Philippe; Sun, Yu; Muñoz, Denise P; Goldstein, Joshua; Nelson, Peter S; Desprez, Pierre-Yves; Campisi, Judith

    2008-01-01

    Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP) developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial–mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL)-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment. PMID:19053174

  2. Chromosome Condensation 1-Like (Chc1L) Is a Novel Tumor Suppressor Involved in Development of Histiocyte-Rich Neoplasms

    PubMed Central

    Newbigging, Susan; Wang, Youdong; Shi, Chang-Xin; Cho, Hae-Ra; Shimizu, Hiroki; Gramolini, Anthony; Liu, Mingyao; Wen, Xiao-Yan

    2015-01-01

    Human chromosomal region 13q14 is a deletion hotspot in prostate cancer, multiple myeloma, and chronic lymphocytic leukemia. Th