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Gerd P. Pfeifer - One of the best experts on this subject based on the ideXlab platform.
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The tumor suppressor RASSF1A in human carcinogenesis: an update.
Histology and Histopathology, 2005Co-Authors: Reinhard Dammann, Claudia Seidel, M. Strunnikova, M. Rastetter, K. Baier, Undraga Schagdarsurengin, Gerd P. PfeiferAbstract:Summary. Loss of heterozygosity of the small arm of chromosome 3 is one of the most common alterations in human cancer. Most notably, a segment in 3p21.3 is frequently lost in lung cancer and several other carcinomas. We and others have identified a novel Ras effector at this segment, which was termed Ras Association Domain family 1 (RASSF1A) gene. RASSF1 consists of two main variants (RASSF1A and RASSF1C), which are transcribed from distinct CpG island promoters. Aberrant methylation of the RASSF1A promoter region is one of the most frequent epigenetic inactivation events detected in human cancer and leads to silencing of RASSF1A. Hypermethylation of RASSF1A was commonly observed in primary tumors including lung, breast, pancreas, kidney, liver, cervix, nasopharyngeal, prostate, thyroid and other cancers. Moreover, RASSF1A methylation was frequently detected in body fluids including blood, urine, nipple aspirates, sputum and bronchial alveolar lavages. Inactivation of RASSF1A was associated with an advanced tumor stage (e.g. bladder, brain, prostate, gastric tumors) and poor prognosis (e.g. lung, sarcoma and breast cancer). Detection of aberrant RASSF1A methylation may serve as a diagnostic and prognostic marker. The functional analyses of RASSF1A reveal an involvement in apoptotic signaling, microtubule stabilization and mitotic progression. The tumor suppressor RASSF1A may act as a negative Ras effector inhibiting cell growth and inducing cell death. Thus, RASSF1A may represent an epigenetically inactivated bona fide tumor suppressor in human carcinogenesis.
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Frequent promoter methylation of tumor-related genes in sporadic and men2-associated pheochromocytomas.
Experimental and clinical endocrinology & diabetes : official journal German Society of Endocrinology [and] German Diabetes Association, 2005Co-Authors: Reinhard Dammann, Claudia Seidel, Gerd P. Pfeifer, Undraga Schagdarsurengin, C. Trümpler, C. Hoang-vu, Oliver Gimm, H. Dralle, Michael BrauckhoffAbstract:Hypermethylation of CpG island promoters is associated with transcriptional inactivation of tumor suppressor genes in neoplasia. Inactivation of p16 and Pten was related to the development of pheochromocytomas. In this report, we investigated the methylation status of the p16INK4a cell cycle inhibitor gene and other prominent tumor-related genes ( PTEN, RASSF1 A, CDH1, MSH2, MLH1, VHL, and TIMP3) in sporadic and multiple endocrine neoplasia type 2 (MEN2) pheochromocytomas by methylation-specific PCR. Hypermethylation was detected in 48 % of pheochromocytomas for RASSF1 A, 24 % for p16, 36 % for MSH2, 16 % for CDH1, and 8 % for PTEN. No VHL, MLH1, and TIMP3 methylation was observed. Interestingly, the frequency of p16 inactivation in familial tumors was higher (5 out of 12, 42 %) than in sporadic tumors (1 out of 13, 8 %; p = 0.047) and RASSF1 A inactivation was more common in the hereditary tumors (58 %) compared to the sporadic tumors (38 %). Combined methylation of RASSF1 A and p16 was found only in MEN2-related pheochromocytomas. Thus, a subset of hereditary pheochromocytomas displays preferential methylation of p16 and RASSF1 A.
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Tumor Susceptibility of RASSF1a Knockout Mice
Cancer research, 2005Co-Authors: Stella Tommasi, Reinhard Dammann, Zhongqiu Zhang, Yian Wang, Limin Liu, Walter Tsark, Sharon P. Wilczynski, Ming You, Gerd P. PfeiferAbstract:The human Ras association domain family 1 (RASSF1) gene is located at 3p21.3 in an area that is believed to harbor at least one important tumor suppressor gene. The two major isoforms of RASSF1, RASSF1A and RASSF1C, are distinguished by alternative NH2-terminal exons and the two transcripts initiate in two separate CpG islands. RASSF1A is one of the most frequently inactivated genes described thus far in human solid tumors. Inactivation of RASSF1A most commonly involves methylation of the promoter and CpG island associated with the RASSF1A isoform. In contrast, RASSF1C is almost never inactivated in tumors. Here, we have derived RASSF1a knockout mice in which exon 1-α of the RASSF1 gene was deleted, leading to specific loss of RASSF1a but not RASSF1c transcripts. RASSF1a-targeted mice were viable and fertile. RASSF1a−/− mice were prone to spontaneous tumorigenesis in advanced age (18–20 months). Whereas only two tumors developed in 48 wild-type mice, six tumors were found in 35 RASSF1a+/− mice (P
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Epigenetic inactivation of the Ras-association domain family 1 (RASSF1A) gene and its function in human carcinogenesis.
Histology and histopathology, 2003Co-Authors: Reinhard Dammann, Claudia Seidel, M. Strunnikova, M. Rastetter, Undraga Schagdarsurengin, Limin Liu, Stefania Tommasi, Gerd P. PfeiferAbstract:Summary. The Ras GTPases are a superfamily of molecular switches that regulate cellular proliferation and apoptosis in response to extra-cellular signals. The regulation of these pathways depends on the interaction of the GTPases with specific effectors. Recently, we have cloned and characterized a novel gene encoding a putative Ras effector: the Ras-association domain family 1 (RASSF1) gene. The RASSF1gene is located in the chromosomal segment of 3p21.3. The high allelic loss in a variety of cancers suggested a crucial role of this region in tumorigenesis. At least two forms of RASSF1 are present in normal human cells. The RASSF1A isoform is highly epigenetically inactivated in lung, breast, ovarian, kidney, prostate, thyroid and several other carcinomas. Re-expression of RASSF1A reduced the growth of human cancer cells supporting a role for RASSF1 as a tumor suppressor gene. RASSF1A inactivation and K-ras activation are mutually exclusive events in the development of certain carcinomas. This observation could further pinpoint the function of RASSF1A as a negative effector of Ras in a pro-apoptotic signaling pathway. In malignant mesothelioma and gastric cancer RASSF1A methylation is associated with virus infection of SV40 and EBV, respectively, and suggests a causal relationship between viral infection and progressive RASSF1A methylation in carcinogenesis. Furthermore, a significant correlation between RASSF1A methylation and impaired lung cancer patient survival was reported, and RASSF1A silencing was correlated with several parameters of poor prognosis and advanced tumor stage (e.g. poor differentiation, aggressiveness, and invasion). Thus, RASSF1A methylation could serve as a useful marker for the prognosis of cancer patients and could become important in early detection of cancer.
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RASSF3 and NORE1: identification and cloning of two human homologues of the putative tumor suppressor gene RASSF1.
Oncogene, 2002Co-Authors: Stella Tommasi, Reinhard Dammann, Joseph Avruch, Seung-gi Jin, Xian-feng Zhang, Gerd P. PfeiferAbstract:RASSF1A, one of the two major isoforms of the putative tumor suppressor gene RASSF1, located at 3p21.3, is inactivated in a variety of human cancers including lung, breast, bladder and renal cell carcinomas. We have isolated and cloned two human homologues of this gene, RASSF3 and NORE1, located at 12q14.1 and 1q32.1, respectively. Both RASSF3 and NORE1 share almost 60% homology, at the amino acid level, with RASSF1. The RASSF3 gene contains five exons and encodes a 247 amino acid protein (MW of 28.6 kDa) with a highly conserved Ras association (RalGDS/AF-6) (RA) domain at the C-terminus. RASSF3 is ubiquitously expressed in all normal tissues and cancer cell lines analysed. NORE1, which is homologous to the previously described mouse Nore1 gene, exists in at least two spliced isoforms, A and B. Transcript A encodes a protein of 418 amino acids (MW or 47 kDa) while transcript B contains an ORF of 265 aa (MW of 30.5 kDa). Both share a RA domain, encoded by exons 3 through 6. NORE1A and NORE1B are expressed in most of the normal tissues analysed but they appear to be down-regulated in several cancer cell lines. However, contrary to RASSF1A, gene silencing by methylation of the CpG islands at which the two NORE1 transcripts initiate is not a common event in human primary tumors. RASSF3 and NORE1B are very similar, at the N-terminus, to the splice variant C of RASSF1 (RASSF1C), which does not seem to be involved in tumorigenesis. NORE1A is most closely related to RASSF1A, for sequence homology and genomic organization. However, aberrations in tumors have so far not been found. The presence of a Ras association domain common to NORE1, RASSF1, and RASSF3 suggests their possible involvement in Ras-like signaling pathways.
Lela Buckingham - One of the best experts on this subject based on the ideXlab platform.
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Abstract 3586: Epigenetic influence on ethnic disparities in non-small cell lung cancer
Epidemiology, 2012Co-Authors: Lela Buckingham, Marin Sekosan, Karen Ferrar, Emira Hadziahmetovic, Thomas LadAbstract:Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL African Americans are more likely to develop lung cancer and die from it than any other ethnic group. Complex biological, environmental, political and cultural factors contribute to this disparity. The purpose of the current project is to examine the relationship between epigenetic factors, gender, ethnicity and outcome in a retrospective study of patients with surgically-treated early stage lung cancer. Fixed primary tumor tissues from a private (RMC) and a public (JHS-CCH) institution were analyzed in this study. The RMC group consisted of 132 patients with stage Ib, IIa and IIb NSCLC, 22% African-American (AA) and 52% female. The JHS-CCH group consisted of 88 patients, 62% AA and 43% female. Five year survival was achieved by 85% of women vs 67% of men in the RMC group (Chi square p=0.022). 68% of Caucasians vs 53% AA survived five years in the RMC group (p=0.186). To investigate the role of epigenetic influences on survival, promoter methylation of Ras association domain family protein 1, RASSF1A, was investigated. Associations between inactivation of the RASSF1A tumor suppressor and poor outcome in lung and other cancers have been reported in several studies. Promoter methylation was quantified using pyrosequencing. Percent methylation of RASSF1 at cytosine position –36 (A of ATG=+1) was more frequent in AA (41% of cases) than in Caucasians (20% of cases) in the RMC group (p=0.023) compared to 69% of cases in the JHS-CCH group. Methylation levels of RASSF1 at all CpG sites tested were higher in the JHS-CCH group than in the RMC group. Kaplan-Meier analysis was performed on dichotomized hypermethylation status compared to five-year survival (5YS). Promoter hypermethylation of RASSF1 was significantly associated with shortened 5YS in AA (p=0.005), compared to Caucasians (p=0.197) in the RMC group. Although 5YS was marginally shortened with hypermethylation of RASSF1 in men in the RMC group (p=0.123), no significant effects were seen with regard to gender. These results suggest that biomarkers can have differential effects, based on genetic background and support analysis of epigenetic biomarkers to address disparities and develop more personalized treatment strategies for individual patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3586. doi:1538-7445.AM2012-3586
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PTEN, RASSF1 and DAPK site‐specific hypermethylation and outcome in surgically treated stage I and II nonsmall cell lung cancer patients
International journal of cancer, 2010Co-Authors: Lela Buckingham, L. Penfield Faber, Anthony W. Kim, Michael J. Liptay, Carter J. Barger, Sanjib Basu, Mary J. Fidler, Kelly Walters, Philip Bonomi, John S. CoonAbstract:The primary objective of this study is to identify prognostic site-specific epigenetic changes in surgically treated Stage I and II nonsmall cell lung cancer (NSCLC) patients by quantifying methylation levels at multiple CpG sites within each gene promoter. Paraffin-embedded tumors from stage Ib, IIa and IIb in training and validation groups of 75 and 57 surgically treated NSCLC patients, respectively, were analyzed for p16, MGMT, RASSF1, RASSF5, CDH1, LET7, DAPK and PTEN promoter hypermethylation. Hypermethylation status was quantified individually at multiple CpG sites within each promoter by pyrosequencing. Molecular and clinical characteristics with time to recurrence (TTR) and overall survival (OS) were evaluated. Overall average promoter methylation levels of MGMT and RASSF1 were significantly higher in smokers than in nonsmokers (p = 0.006 and p = 0.029, respectively). Methylation levels of the p16 promoter were significantly higher in squamous cell carcinoma than in adenocarcinoma (p = 0.020). In univariate analysis, hypermethylation of RASSF1 at CpG sites −53 and −48 and PTEN at CpG site −1310 were the significantly associated with shorter TTR (p = 0.002 and p < 0.000, respectively). Hypermethylation of PTEN at −1310 and DAPK at −1482 were most significantly associated with outcome in multivariate analysis. These results show that methylation of specific promoter CpG sites in PTEN, RASSF1 and DAPK is associated with outcome in early stage surgically treated NSCLC.
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pten RASSF1 and dapk site specific hypermethylation and outcome in surgically treated stage i and ii nonsmall cell lung cancer patients
International Journal of Cancer, 2010Co-Authors: Lela Buckingham, Anthony W. Kim, Michael J. Liptay, Carter J. Barger, Sanjib Basu, Mary J. Fidler, Kelly Walters, Philip Bonomi, Penfield L Faber, John S. CoonAbstract:The primary objective of this study is to identify prognostic site-specific epigenetic changes in surgically treated Stage I and II nonsmall cell lung cancer (NSCLC) patients by quantifying methylation levels at multiple CpG sites within each gene promoter. Paraffin-embedded tumors from stage Ib, IIa and IIb in training and validation groups of 75 and 57 surgically treated NSCLC patients, respectively, were analyzed for p16, MGMT, RASSF1, RASSF5, CDH1, LET7, DAPK and PTEN promoter hypermethylation. Hypermethylation status was quantified individually at multiple CpG sites within each promoter by pyrosequencing. Molecular and clinical characteristics with time to recurrence (TTR) and overall survival (OS) were evaluated. Overall average promoter methylation levels of MGMT and RASSF1 were significantly higher in smokers than in nonsmokers (p = 0.006 and p = 0.029, respectively). Methylation levels of the p16 promoter were significantly higher in squamous cell carcinoma than in adenocarcinoma (p = 0.020). In univariate analysis, hypermethylation of RASSF1 at CpG sites −53 and −48 and PTEN at CpG site −1310 were the significantly associated with shorter TTR (p = 0.002 and p < 0.000, respectively). Hypermethylation of PTEN at −1310 and DAPK at −1482 were most significantly associated with outcome in multivariate analysis. These results show that methylation of specific promoter CpG sites in PTEN, RASSF1 and DAPK is associated with outcome in early stage surgically treated NSCLC.
John S. Coon - One of the best experts on this subject based on the ideXlab platform.
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PTEN, RASSF1 and DAPK site‐specific hypermethylation and outcome in surgically treated stage I and II nonsmall cell lung cancer patients
International journal of cancer, 2010Co-Authors: Lela Buckingham, L. Penfield Faber, Anthony W. Kim, Michael J. Liptay, Carter J. Barger, Sanjib Basu, Mary J. Fidler, Kelly Walters, Philip Bonomi, John S. CoonAbstract:The primary objective of this study is to identify prognostic site-specific epigenetic changes in surgically treated Stage I and II nonsmall cell lung cancer (NSCLC) patients by quantifying methylation levels at multiple CpG sites within each gene promoter. Paraffin-embedded tumors from stage Ib, IIa and IIb in training and validation groups of 75 and 57 surgically treated NSCLC patients, respectively, were analyzed for p16, MGMT, RASSF1, RASSF5, CDH1, LET7, DAPK and PTEN promoter hypermethylation. Hypermethylation status was quantified individually at multiple CpG sites within each promoter by pyrosequencing. Molecular and clinical characteristics with time to recurrence (TTR) and overall survival (OS) were evaluated. Overall average promoter methylation levels of MGMT and RASSF1 were significantly higher in smokers than in nonsmokers (p = 0.006 and p = 0.029, respectively). Methylation levels of the p16 promoter were significantly higher in squamous cell carcinoma than in adenocarcinoma (p = 0.020). In univariate analysis, hypermethylation of RASSF1 at CpG sites −53 and −48 and PTEN at CpG site −1310 were the significantly associated with shorter TTR (p = 0.002 and p < 0.000, respectively). Hypermethylation of PTEN at −1310 and DAPK at −1482 were most significantly associated with outcome in multivariate analysis. These results show that methylation of specific promoter CpG sites in PTEN, RASSF1 and DAPK is associated with outcome in early stage surgically treated NSCLC.
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pten RASSF1 and dapk site specific hypermethylation and outcome in surgically treated stage i and ii nonsmall cell lung cancer patients
International Journal of Cancer, 2010Co-Authors: Lela Buckingham, Anthony W. Kim, Michael J. Liptay, Carter J. Barger, Sanjib Basu, Mary J. Fidler, Kelly Walters, Philip Bonomi, Penfield L Faber, John S. CoonAbstract:The primary objective of this study is to identify prognostic site-specific epigenetic changes in surgically treated Stage I and II nonsmall cell lung cancer (NSCLC) patients by quantifying methylation levels at multiple CpG sites within each gene promoter. Paraffin-embedded tumors from stage Ib, IIa and IIb in training and validation groups of 75 and 57 surgically treated NSCLC patients, respectively, were analyzed for p16, MGMT, RASSF1, RASSF5, CDH1, LET7, DAPK and PTEN promoter hypermethylation. Hypermethylation status was quantified individually at multiple CpG sites within each promoter by pyrosequencing. Molecular and clinical characteristics with time to recurrence (TTR) and overall survival (OS) were evaluated. Overall average promoter methylation levels of MGMT and RASSF1 were significantly higher in smokers than in nonsmokers (p = 0.006 and p = 0.029, respectively). Methylation levels of the p16 promoter were significantly higher in squamous cell carcinoma than in adenocarcinoma (p = 0.020). In univariate analysis, hypermethylation of RASSF1 at CpG sites −53 and −48 and PTEN at CpG site −1310 were the significantly associated with shorter TTR (p = 0.002 and p < 0.000, respectively). Hypermethylation of PTEN at −1310 and DAPK at −1482 were most significantly associated with outcome in multivariate analysis. These results show that methylation of specific promoter CpG sites in PTEN, RASSF1 and DAPK is associated with outcome in early stage surgically treated NSCLC.
Reinhard Dammann - One of the best experts on this subject based on the ideXlab platform.
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The tumor suppressor RASSF1A in human carcinogenesis: an update.
Histology and Histopathology, 2005Co-Authors: Reinhard Dammann, Claudia Seidel, M. Strunnikova, M. Rastetter, K. Baier, Undraga Schagdarsurengin, Gerd P. PfeiferAbstract:Summary. Loss of heterozygosity of the small arm of chromosome 3 is one of the most common alterations in human cancer. Most notably, a segment in 3p21.3 is frequently lost in lung cancer and several other carcinomas. We and others have identified a novel Ras effector at this segment, which was termed Ras Association Domain family 1 (RASSF1A) gene. RASSF1 consists of two main variants (RASSF1A and RASSF1C), which are transcribed from distinct CpG island promoters. Aberrant methylation of the RASSF1A promoter region is one of the most frequent epigenetic inactivation events detected in human cancer and leads to silencing of RASSF1A. Hypermethylation of RASSF1A was commonly observed in primary tumors including lung, breast, pancreas, kidney, liver, cervix, nasopharyngeal, prostate, thyroid and other cancers. Moreover, RASSF1A methylation was frequently detected in body fluids including blood, urine, nipple aspirates, sputum and bronchial alveolar lavages. Inactivation of RASSF1A was associated with an advanced tumor stage (e.g. bladder, brain, prostate, gastric tumors) and poor prognosis (e.g. lung, sarcoma and breast cancer). Detection of aberrant RASSF1A methylation may serve as a diagnostic and prognostic marker. The functional analyses of RASSF1A reveal an involvement in apoptotic signaling, microtubule stabilization and mitotic progression. The tumor suppressor RASSF1A may act as a negative Ras effector inhibiting cell growth and inducing cell death. Thus, RASSF1A may represent an epigenetically inactivated bona fide tumor suppressor in human carcinogenesis.
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Frequent promoter methylation of tumor-related genes in sporadic and men2-associated pheochromocytomas.
Experimental and clinical endocrinology & diabetes : official journal German Society of Endocrinology [and] German Diabetes Association, 2005Co-Authors: Reinhard Dammann, Claudia Seidel, Gerd P. Pfeifer, Undraga Schagdarsurengin, C. Trümpler, C. Hoang-vu, Oliver Gimm, H. Dralle, Michael BrauckhoffAbstract:Hypermethylation of CpG island promoters is associated with transcriptional inactivation of tumor suppressor genes in neoplasia. Inactivation of p16 and Pten was related to the development of pheochromocytomas. In this report, we investigated the methylation status of the p16INK4a cell cycle inhibitor gene and other prominent tumor-related genes ( PTEN, RASSF1 A, CDH1, MSH2, MLH1, VHL, and TIMP3) in sporadic and multiple endocrine neoplasia type 2 (MEN2) pheochromocytomas by methylation-specific PCR. Hypermethylation was detected in 48 % of pheochromocytomas for RASSF1 A, 24 % for p16, 36 % for MSH2, 16 % for CDH1, and 8 % for PTEN. No VHL, MLH1, and TIMP3 methylation was observed. Interestingly, the frequency of p16 inactivation in familial tumors was higher (5 out of 12, 42 %) than in sporadic tumors (1 out of 13, 8 %; p = 0.047) and RASSF1 A inactivation was more common in the hereditary tumors (58 %) compared to the sporadic tumors (38 %). Combined methylation of RASSF1 A and p16 was found only in MEN2-related pheochromocytomas. Thus, a subset of hereditary pheochromocytomas displays preferential methylation of p16 and RASSF1 A.
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Tumor Susceptibility of RASSF1a Knockout Mice
Cancer research, 2005Co-Authors: Stella Tommasi, Reinhard Dammann, Zhongqiu Zhang, Yian Wang, Limin Liu, Walter Tsark, Sharon P. Wilczynski, Ming You, Gerd P. PfeiferAbstract:The human Ras association domain family 1 (RASSF1) gene is located at 3p21.3 in an area that is believed to harbor at least one important tumor suppressor gene. The two major isoforms of RASSF1, RASSF1A and RASSF1C, are distinguished by alternative NH2-terminal exons and the two transcripts initiate in two separate CpG islands. RASSF1A is one of the most frequently inactivated genes described thus far in human solid tumors. Inactivation of RASSF1A most commonly involves methylation of the promoter and CpG island associated with the RASSF1A isoform. In contrast, RASSF1C is almost never inactivated in tumors. Here, we have derived RASSF1a knockout mice in which exon 1-α of the RASSF1 gene was deleted, leading to specific loss of RASSF1a but not RASSF1c transcripts. RASSF1a-targeted mice were viable and fertile. RASSF1a−/− mice were prone to spontaneous tumorigenesis in advanced age (18–20 months). Whereas only two tumors developed in 48 wild-type mice, six tumors were found in 35 RASSF1a+/− mice (P
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Epigenetic inactivation of the Ras-association domain family 1 (RASSF1A) gene and its function in human carcinogenesis.
Histology and histopathology, 2003Co-Authors: Reinhard Dammann, Claudia Seidel, M. Strunnikova, M. Rastetter, Undraga Schagdarsurengin, Limin Liu, Stefania Tommasi, Gerd P. PfeiferAbstract:Summary. The Ras GTPases are a superfamily of molecular switches that regulate cellular proliferation and apoptosis in response to extra-cellular signals. The regulation of these pathways depends on the interaction of the GTPases with specific effectors. Recently, we have cloned and characterized a novel gene encoding a putative Ras effector: the Ras-association domain family 1 (RASSF1) gene. The RASSF1gene is located in the chromosomal segment of 3p21.3. The high allelic loss in a variety of cancers suggested a crucial role of this region in tumorigenesis. At least two forms of RASSF1 are present in normal human cells. The RASSF1A isoform is highly epigenetically inactivated in lung, breast, ovarian, kidney, prostate, thyroid and several other carcinomas. Re-expression of RASSF1A reduced the growth of human cancer cells supporting a role for RASSF1 as a tumor suppressor gene. RASSF1A inactivation and K-ras activation are mutually exclusive events in the development of certain carcinomas. This observation could further pinpoint the function of RASSF1A as a negative effector of Ras in a pro-apoptotic signaling pathway. In malignant mesothelioma and gastric cancer RASSF1A methylation is associated with virus infection of SV40 and EBV, respectively, and suggests a causal relationship between viral infection and progressive RASSF1A methylation in carcinogenesis. Furthermore, a significant correlation between RASSF1A methylation and impaired lung cancer patient survival was reported, and RASSF1A silencing was correlated with several parameters of poor prognosis and advanced tumor stage (e.g. poor differentiation, aggressiveness, and invasion). Thus, RASSF1A methylation could serve as a useful marker for the prognosis of cancer patients and could become important in early detection of cancer.
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RASSF3 and NORE1: identification and cloning of two human homologues of the putative tumor suppressor gene RASSF1.
Oncogene, 2002Co-Authors: Stella Tommasi, Reinhard Dammann, Joseph Avruch, Seung-gi Jin, Xian-feng Zhang, Gerd P. PfeiferAbstract:RASSF1A, one of the two major isoforms of the putative tumor suppressor gene RASSF1, located at 3p21.3, is inactivated in a variety of human cancers including lung, breast, bladder and renal cell carcinomas. We have isolated and cloned two human homologues of this gene, RASSF3 and NORE1, located at 12q14.1 and 1q32.1, respectively. Both RASSF3 and NORE1 share almost 60% homology, at the amino acid level, with RASSF1. The RASSF3 gene contains five exons and encodes a 247 amino acid protein (MW of 28.6 kDa) with a highly conserved Ras association (RalGDS/AF-6) (RA) domain at the C-terminus. RASSF3 is ubiquitously expressed in all normal tissues and cancer cell lines analysed. NORE1, which is homologous to the previously described mouse Nore1 gene, exists in at least two spliced isoforms, A and B. Transcript A encodes a protein of 418 amino acids (MW or 47 kDa) while transcript B contains an ORF of 265 aa (MW of 30.5 kDa). Both share a RA domain, encoded by exons 3 through 6. NORE1A and NORE1B are expressed in most of the normal tissues analysed but they appear to be down-regulated in several cancer cell lines. However, contrary to RASSF1A, gene silencing by methylation of the CpG islands at which the two NORE1 transcripts initiate is not a common event in human primary tumors. RASSF3 and NORE1B are very similar, at the N-terminus, to the splice variant C of RASSF1 (RASSF1C), which does not seem to be involved in tumorigenesis. NORE1A is most closely related to RASSF1A, for sequence homology and genomic organization. However, aberrations in tumors have so far not been found. The presence of a Ras association domain common to NORE1, RASSF1, and RASSF3 suggests their possible involvement in Ras-like signaling pathways.
Geoffrey J. Clark - One of the best experts on this subject based on the ideXlab platform.
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Novel functional interaction between the plasma membrane Ca2+ pump 4b and the proapoptotic tumor suppressor Ras-associated factor 1 (RASSF1)
The Journal of biological chemistry, 2004Co-Authors: Angel L. Armesilla, Judith C. Williams, Mamta H. Buch, Adam Pickard, Michael Emerson, Elizabeth J. Cartwright, Delvac Oceandy, Michele D. Vos, Sheona Gillies, Geoffrey J. ClarkAbstract:Plasma membrane calmodulin-dependent calcium ATPases (PMCAs) are enzymatic systems implicated in the extrusion of calcium from the cell. We and others have previously identified molecular interactions between the cytoplasmic COOH-terminal end of PMCA and PDZ domain-containing proteins. These interactions suggested a new role for PMCA as a modulator of signal transduction pathways. The existence of other intracellular regions in the PMCA molecule prompted us to investigate the possible participation of other domains in interactions with different partner proteins. A two-hybrid screen of a human fetal heart cDNA library, using the region 652-840 of human PMCA4b (located in the catalytic, second intracellular loop) as bait, revealed a novel interaction between PMCA4b and the tumor suppressor RASSF1, a Ras effector protein involved in H-Ras-mediated apoptosis. Immunofluorescence co-localization, immunoprecipitation, and glutathione S-transferase pull-down experiments performed in mammalian cells provided further confirmation of the physical interaction between the two proteins. The interaction domain has been narrowed down to region 74-123 of RASSF1C (144-193 in RASSF1A) and 652-748 of human PMCA4b. The functionality of this interaction was demonstrated by the inhibition of the epidermal growth factor-dependent activation of the Erk pathway when PMCA4b and RASSF1 were co-expressed. This inhibition was abolished by blocking PMCA/RASSSF1 association with an excess of a green fluorescent protein fusion protein containing the region 50-123 of RASSF1C. This work describes a novel protein-protein interaction involving a domain of PMCA other than the COOH terminus. It suggests a function for PMCA4b as an organizer of macromolecular protein complexes, where PMCA4b could recruit diverse proteins through interaction with different domains. Furthermore, the functional association with RASSF1 indicates a role for PMCA4b in the modulation of Ras-mediated signaling.
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The pro-apoptotic Ras effector Nore1 may serve as a Ras-regulated tumor suppressor in the lung.
The Journal of biological chemistry, 2003Co-Authors: Michele D. Vos, Chad A. Ellis, Alfredo Martínez, Teresa Vallecorsa, Geoffrey J. ClarkAbstract:Abstract Ras oncoproteins mediate multiple biological effects by activating multiple effectors. Classically, Ras activation has been associated with enhanced cellular growth and transformation. However, activated forms of Ras may also inhibit growth by inducing senescence, apoptosis, and differentiation. Induction of apoptosis by Ras may be mediated by its effector RASSF1, which appears to function as a tumor suppressor. We now show that the Ras effector Nore1, which is structurally related to RASSF1, can also mediate a Ras-dependent apoptosis. Moreover, an analysis of Nore1 protein expression showed that it is frequently down-regulated in lung tumor cell lines and primary lung tumors. Like RASSF1, this correlates with methylation of the Nore1 promoter rather than gene deletion. Finally, re-introduction of Nore1, driven by its own promoter, impairs the growth in soft agar of a human lung tumor cell line. Consequently, we propose that the Ras effector Nore1 is a member of a family of Ras effector/tumor suppressors that includes RASSF1.
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Ras uses the novel tumor suppressor RASSF1 as an effector to mediate apoptosis.
The Journal of biological chemistry, 2000Co-Authors: Michele D. Vos, Chad A. Ellis, Aaron Bell, Michael J. Birrer, Geoffrey J. ClarkAbstract:Although activated Ras proteins are usually associated with driving growth and transformation, they may also induce senescence, apoptosis, and terminal differentiation. The subversion of these anti-neoplastic effects during Ras-dependent tumor development may be as important as the acquisition of the pro-neoplastic effects. None of the currently identified potential Ras effector proteins can satisfactorily explain the apoptotic action of Ras. Consequently, we have sought to identify novel Ras effectors that may be responsible for apoptosis induction. By examining the EST data base, we identified a potential Ras association domain in the tumor suppressor RASSF1. We now show that RASSF1 binds Ras in a GTP-dependent manner, both in vivo and directly in vitro. Moreover, activated Ras enhances and dominant negative Ras inhibits the cell death induced by transient transfection of RASSF1 into 293-T cells. This cell death appears to be apoptotic in nature, as RASSF1-transfected 293-T cells exhibit membrane blebbing and can be rescued by the addition of a caspase inhibitor. Thus, the RASSF1 tumor suppressor may serve as a novel Ras effector that mediates the apoptotic effects of oncogenic Ras.
