1
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RAS GTPase signalling to alternative effector pathways. Biochem Soc Trans 2021; 48:2241-2252. [PMID: 33125484 DOI: 10.1042/bst20200506] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/21/2020] [Accepted: 09/23/2020] [Indexed: 02/07/2023]
Abstract
RAS GTPases are fundamental regulators of development and drivers of an extraordinary number of human cancers. RAS oncoproteins constitutively signal through downstream effector proteins, triggering cancer initiation, progression and metastasis. In the absence of targeted therapeutics to mutant RAS itself, inhibitors of downstream pathways controlled by the effector kinases RAF and PI3K have become tools in the treatment of RAS-driven tumours. Unfortunately, the efficacy of this approach has been greatly minimized by the prevalence of acquired drug resistance. Decades of research have established that RAS signalling is highly complex, and in addition to RAF and PI3K these small GTPase proteins can interact with an array of alternative effectors that feature RAS binding domains. The consequence of RAS binding to these effectors remains relatively unexplored, but these pathways may provide targets for combinatorial therapeutics. We discuss here three candidate alternative effectors: RALGEFs, RASSF5 and AFDN, detailing their interaction with RAS GTPases and their biological significance. The metastatic nature of RAS-driven cancers suggests more attention should be granted to these alternate pathways, as they are highly implicated in the regulation of cell adhesion, polarity, cell size and cytoskeletal architecture.
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2
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Liu F, Zhang H, Lu S, Wu Z, Zhou L, Cheng Z, Bai Y, Zhao J, Zhang Q, Mao H. Quantitative assessment of gene promoter methylation in non-small cell lung cancer using methylation-sensitive high-resolution melting. Oncol Lett 2018; 15:7639-7648. [PMID: 29725463 PMCID: PMC5920472 DOI: 10.3892/ol.2018.8321] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 02/08/2018] [Indexed: 12/12/2022] Open
Abstract
DNA methylation is closely associated with aberrant epigenetic changes. Previous studies have identified various genes associated with non-small cell lung cancer (NSCLC), but the precise combination responsible for its etiology is still debated. The aim of the present study was to select a new set of NSCLC-related genes using methylation-sensitive high-resolution melting. The promoter methylation status of six selected genes, consisting of protocadherin γ subfamily B, 6 (PCDHGB6), homeobox A9 (HOXA9), O6-methylguanine-DNA methyltransferase (MGMT), microRNA (miR)-126, suppressor of cytokine signaling 3 (SOCS3) and Ras association domain family member 5, also termed NORE1A, was evaluated in 54 NSCLC patients. From these samples, genome-wide DNA was extracted and bisulfite conversion was performed along with fluorogenic quantitative polymerase chain reaction to detect methylation values of the six selected promoters. The present results revealed frequent methylation on PCDHGB6, HOXA9 and miR-126, which contrasted with infrequent methylation on MGMT. The results indicated no methylation on either SOCS3 or NORE1A. The sensitivity and specificity of the methylation assessment were 85.2 and 81.5%, respectively, and the analysis results were validated by pyrosequencing. Furthermore, minute comparison of the association between DNA methylation and clinical features was performed. Overall, these results may provide potential information for the development of better clinical diagnostics and more targeted and effective therapies for NSCLC.
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Affiliation(s)
- Fangming Liu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China.,Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou, Fujian 350002, P.R. China
| | - Honglian Zhang
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
| | - Shaohua Lu
- Department of Pathology, Zhongshan Hospital, Fudan University, Shanghai 200032, P.R. China
| | - Zhenhua Wu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
| | - Lin Zhou
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
| | - Zule Cheng
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
| | - Yanan Bai
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
| | - Jianlong Zhao
- Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou, Fujian 350002, P.R. China
| | - Qiqing Zhang
- Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou, Fujian 350002, P.R. China.,Institute of Biomedical Engineering, Chinese Academy of Medical Science and Peking Union Medical College, The Key Laboratory of Biomaterials of Tianjin, Tianjin 300192, P.R. China
| | - Hongju Mao
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Science, Shanghai 200050, P.R. China
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Delire B, Stärkel P. The Ras/MAPK pathway and hepatocarcinoma: pathogenesis and therapeutic implications. Eur J Clin Invest 2015; 45:609-23. [PMID: 25832714 DOI: 10.1111/eci.12441] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/27/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Hepatocellular carcinoma (HCC) is still a major health problem, often diagnosed at an advanced stage. The multikinase inhibitor sorafenib is to date the sole approved systemic therapy. Several signalling pathways are implicated in tumour development and progression. Among these pathways, the Ras/MAPK pathway is activated in 50-100% of human HCCs and is correlated with a poor prognosis. The aim of this work was to review the main intracellular mechanisms leading to aberrant Ras pathway activation in HCC and the potential therapeutic implications. MATERIALS AND METHODS This review is based on the material found on PubMed up to December 2014. 'Ras signaling, Ras dysregulation, Ras inhibition, MAPK pathway, cancer, hepatocarcinoma and liver cancer' alone or in combination were the main terms used for online research. RESULTS Multiple mechanisms lead to the deregulation of the Ras pathway in liver cancer. Ras and Raf gene mutations are rare events in human hepatocarcinogenesis in contrast to experimental models in rodents. Downregulation of several Ras/MAPK pathway inhibitors such as GAPs, RASSF proteins, DUSP1, Sprouty and Spred proteins is largely implicated in the aberrant activation of this pathway in the context of wild-type Ras and Raf genes. Epigenetic or post-transcriptional mechanisms lead to the downregulation of these tumour suppressor genes. CONCLUSION Ras/MAPK pathway effectors may be considered as potential therapeutic targets in the field of HCC. In particular after the arrival of sorafenib, more Ras/MAPK inhibitors have emerged and are still in preclinical or clinical investigation for HCC therapy.
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Affiliation(s)
- Bénédicte Delire
- Laboratory of Hepato-Gastroenterology, Institut de Recherche Expérimentale et Clinique (IREC), Catholic University of Louvain, Brussels, Belgium
| | - Peter Stärkel
- Laboratory of Hepato-Gastroenterology, Institut de Recherche Expérimentale et Clinique (IREC), Catholic University of Louvain, Brussels, Belgium.,Department of Gastroenterology, Saint-Luc Academic Hospital and Institute of Clinical Research, Catholic University of Louvain, Brussels, Belgium
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Liang YY, Chen MY, Hua YJ, Chen S, Zheng LS, Cao X, Peng LX, Xie P, Huang BJ, Sun R, Wang L, Xiang YQ, Guo X, Qian CN. Downregulation of Ras association domain family member 6 (RASSF6) underlies the treatment resistance of highly metastatic nasopharyngeal carcinoma cells. PLoS One 2014; 9:e100843. [PMID: 25028967 PMCID: PMC4100732 DOI: 10.1371/journal.pone.0100843] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 05/30/2014] [Indexed: 11/24/2022] Open
Abstract
Radiation and cisplatin-based chemotherapy are major treatments for nasopharyngeal carcinoma (NPC). However, a major impediment for further improving the cure rate is the development of treatment resistance with an undetermined molecular mechanism in metastatic NPC cells. Our established, highly metastatic NPC cells have been reported to be more resistant to cisplatin chemotherapy. In the present study, we found that Ras association domain family member 6 (RASSF6) was downregulated in highly metastatic cells but upregulated in low metastatic cells in comparison to their parental cell line. Ectopic-expression of RASSF6 enhanced the sensitivity of highly metastatic NPC cells to cisplatin or radiation by enhancing apoptosis. RASSF6 depletion conversely reduced treatment sensitivity by decreasing the apoptosis rate. Over-expression of RASSF6 in highly metastatic NPC cells could enhance the phosphorylation of JNK when exposed to cisplatin or radiation treatment, while knocking down RASSF6 in low metastatic NPC cells could reduce the level of phospho-JNK when exposed to the same treatments. The activation of JNK signaling by RASSF6 and its subsequent sensitivity to apoptosis in NPC cells could be inhibited by applying the JNK inhibitor SP600125. In conclusion, the downregulation of RASSF6 in highly metastatic NPC cells contributed to their treatment resistance, and over-expression of RASSF6 conferred treatment sensitivity to highly metastatic NPC cells by activating JNK signaling. RASSF6 could be a valuable molecular marker for identifying sensitive metastatic NPC tumors during cisplatin treatment or radiotherapy.
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Affiliation(s)
- Ying-Ying Liang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Ming-Yuan Chen
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yi-Jun Hua
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Shi Chen
- Department of Gastroesophageal surgery, The Sixth Affliated Hospital (Gastrointestinal and Anal Hospital), Sun Yat-sen University, GuangZhou, China
| | - Li-Sheng Zheng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xue Cao
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Li-Xia Peng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Ping Xie
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Bi-Jun Huang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Rui Sun
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Lin Wang
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Yan-Qun Xiang
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Xiang Guo
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Chao-Nan Qian
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China
- Department of Nasopharyngeal Carcinoma, Sun Yat-sen University Cancer Center, Guangzhou, China
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5
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Yang R, Kong E, Jin J, Hergovich A, Püschel AW. Rassf5 and Ndr kinases regulate neuronal polarity through Par3 phosphorylation in a novel pathway. J Cell Sci 2014; 127:3463-76. [PMID: 24928906 DOI: 10.1242/jcs.146696] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The morphology and polarized growth of cells depend on pathways that control the asymmetric distribution of regulatory factors. The evolutionarily conserved Ndr kinases play important roles in cell polarity and morphogenesis in yeast and invertebrates but it is unclear whether they perform a similar function in mammalian cells. Here, we analyze the function of mammalian Ndr1 and Ndr2 (also known as STK38 or STK38L, respectively) in the establishment of polarity in neurons. We show that they act downstream of the tumor suppressor Rassf5 and upstream of the polarity protein Par3 (also known as PARD3). Rassf5 and Ndr1 or Ndr2 are required during the polarization of hippocampal neurons to prevent the formation of supernumerary axons. Mechanistically, the Ndr kinases act by phosphorylating Par3 at Ser383 to inhibit its interaction with dynein, thereby polarizing the distribution of Par3 and reinforcing axon specification. Our results identify a novel Rassf5-Ndr-Par3 signaling cascade that regulates the transport of Par3 during the establishment of neuronal polarity. Their role in neuronal polarity suggests that Ndr kinases perform a conserved function as regulators of cell polarity.
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Affiliation(s)
- Rui Yang
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Schloßplatz 5, D-48149 Münster, Germany
| | - Eryan Kong
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Schloßplatz 5, D-48149 Münster, Germany
| | - Jing Jin
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Schloßplatz 5, D-48149 Münster, Germany
| | | | - Andreas W Püschel
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität Münster, Schloßplatz 5, D-48149 Münster, Germany Cells-in-Motion Cluster of Excellence, University of Münster, D-48149 Münster, Germany
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6
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Zhou Y, Zhang X, Klibanski A. Genetic and epigenetic mutations of tumor suppressive genes in sporadic pituitary adenoma. Mol Cell Endocrinol 2014; 386:16-33. [PMID: 24035864 PMCID: PMC3943596 DOI: 10.1016/j.mce.2013.09.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 09/03/2013] [Indexed: 12/28/2022]
Abstract
Human pituitary adenomas are the most common intracranial neoplasms. Approximately 5% of them are familial adenomas. Patients with familial tumors carry germline mutations in predisposition genes, including AIP, MEN1 and PRKAR1A. These mutations are extremely rare in sporadic pituitary adenomas, which therefore are caused by different mechanisms. Multiple tumor suppressive genes linked to sporadic tumors have been identified. Their inactivation is caused by epigenetic mechanisms, mainly promoter hypermethylation, and can be placed into two groups based on their functional interaction with tumor suppressors RB or p53. The RB group includes CDKN2A, CDKN2B, CDKN2C, RB1, BMP4, CDH1, CDH13, GADD45B and GADD45G; AIP and MEN1 genes also belong to this group. The p53 group includes MEG3, MGMT, PLAGL1, RASSF1, RASSF3 and SOCS1. We propose that the tumor suppression function of these genes is mainly mediated by the RB and p53 pathways. We also discuss possible tumor suppression mechanisms for individual genes.
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Affiliation(s)
- Yunli Zhou
- Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States
| | - Xun Zhang
- Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States
| | - Anne Klibanski
- Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States.
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7
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Liang YY, Zheng LS, Wu YZ, Peng LX, Cao Y, Cao X, Xie P, Huang BJ, Qian CN. RASSF6 promotes p21(Cip1/Waf1)-dependent cell cycle arrest and apoptosis through activation of the JNK/SAPK pathway in clear cell renal cell carcinoma. Cell Cycle 2014; 13:1440-9. [PMID: 24626183 DOI: 10.4161/cc.28416] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Clear cell renal cell carcinoma (ccRCC) is a highly aggressive and common pathological subtype of renal cancer. This cancer is characterized by biallelic inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene, which leads to the accumulation of hypoxia-inducible factors (HIFs). Although therapies targeted at HIFs can significantly improve survival, nearly all patients with advanced ccRCC eventually succumb to the disease. Thus, additional oncogenic events are thought to be involved in the development of ccRCC tumors. In this study, we investigated the role of RASSF6 in ccRCC. Downregulation of RASSF6 was commonly observed in primary tumors relative to matched adjacent normal tissues. Moreover, functional studies established that ectopic re-expression of RASSF6 in ccRCC cells inhibited cell proliferation, clonogenicity, and tumor growth in mice, whereas silencing of RASSF6 dramatically enhanced cell proliferation in vitro and in vivo. Mechanistic investigation suggested that RASSF6 triggers p21(Cip1/Waf1) accumulation to induce G 1 cell cycle arrest and promote apoptosis upon exposure to pro-apoptotic agents, and both of these mechanisms appear to be mediated by activated JNK signaling. Together, these findings suggest that RASSF6 may play a tumor suppressor role in the progression of ccRCC.
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Affiliation(s)
- Ying-Ying Liang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Li-Sheng Zheng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Yuan-Zhong Wu
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Li-Xia Peng
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Yun Cao
- Department of Pathology; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Xue Cao
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Ping Xie
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Bi-Jun Huang
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
| | - Chao-Nan Qian
- State Key Laboratory of Oncology in South China and Collaborative Innovation Center of Cancer Medicine; Sun Yat-sen University Cancer Center; Guangzhou, China
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Volodko N, Gordon M, Salla M, Ghazaleh HA, Baksh S. RASSF tumor suppressor gene family: Biological functions and regulation. FEBS Lett 2014; 588:2671-84. [DOI: 10.1016/j.febslet.2014.02.041] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 01/22/2023]
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9
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Richter AM, Haag T, Walesch S, Herrmann-Trost P, Marsch WC, Kutzner H, Helmbold P, Dammann RH. Aberrant Promoter Hypermethylation of RASSF Family Members in Merkel Cell Carcinoma. Cancers (Basel) 2013; 5:1566-76. [PMID: 24252868 PMCID: PMC3875954 DOI: 10.3390/cancers5041566] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 10/23/2013] [Accepted: 11/08/2013] [Indexed: 12/03/2022] Open
Abstract
Merkel cell carcinoma (MCC) is one of the most aggressive cancers of the skin. RASSFs are a family of tumor suppressors that are frequently inactivated by promoter hypermethylation in various cancers. We studied CpG island promoter hypermethylation in MCC of RASSF2, RASSF5A, RASSF5C and RASSF10 by combined bisulfite restriction analysis (COBRA) in MCC samples and control tissue. We found RASSF2 to be methylated in three out of 43 (7%), RASSF5A in 17 out of 39 (44%, but also 43% in normal tissue), RASSF5C in two out of 26 (8%) and RASSF10 in 19 out of 84 (23%) of the cancer samples. No correlation between the methylation status of the analyzed RASSFs or between RASSF methylation and MCC characteristics (primary versus metastatic, Merkel cell polyoma virus infection, age, sex) was found. Our results show that RASSF2, RASSF5C and RASSF10 are aberrantly hypermethylated in MCC to a varying degree and this might contribute to Merkel cell carcinogenesis.
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Affiliation(s)
- Antje M. Richter
- Institute for Genetics, University of Giessen, Giessen D-35392, Germany; E-Mails: (A.M.R.); (T.H.); (S.W.)
| | - Tanja Haag
- Institute for Genetics, University of Giessen, Giessen D-35392, Germany; E-Mails: (A.M.R.); (T.H.); (S.W.)
| | - Sara Walesch
- Institute for Genetics, University of Giessen, Giessen D-35392, Germany; E-Mails: (A.M.R.); (T.H.); (S.W.)
| | | | - Wolfgang C. Marsch
- Department of Dermatology, University of Halle, Halle D-06120, Germany; E-Mail:
| | | | - Peter Helmbold
- Department of Dermatology, University of Heidelberg, Heidelberg D-69120, Germany; E-Mail: Peter.
| | - Reinhard H. Dammann
- Institute for Genetics, University of Giessen, Giessen D-35392, Germany; E-Mails: (A.M.R.); (T.H.); (S.W.)
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10
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Chan JJ, Katan M. PLCɛ and the RASSF family in tumour suppression and other functions. Adv Biol Regul 2013; 53:258-279. [PMID: 23958207 DOI: 10.1016/j.jbior.2013.07.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 07/15/2013] [Indexed: 06/02/2023]
Abstract
Not all proteins implicated in direct binding to Ras appear to have a positive role in the generation and progression of tumours; examples include Phospholipase C epsilon (PLCɛ) and some members of the Ras-association domain family (RASSF). The RASSF family comprises of ten members, known as RASSF1 to RASSF10. PLCɛ and RASSF members carry a common Ras-association domain (RA) that can potentially bind Ras oncoproteins and mediate Ras-regulated functions. RASSF1 to RASSF6 also share a common SARAH domain that facilitates protein-protein interactions with other SARAH domain proteins. The majority of the family are frequently downregulated by epigenetic silencing in cancers. They are implicated in various important biological processes including apoptosis, microtubule stabilisation and cell cycle regulation. Recent studies have reinforced the tumour suppressive properties of the RASSF family, with new evidence of emerging pathways and novel functions that suggest a wider role for these proteins. This review will first describe an emerging role of PLCɛ in tumour suppression and then focus on and summarise the new findings on the RASSF family in the last five years to consolidate their well-established functions, and highlight the new regulatory roles of specific RASSF members.
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Affiliation(s)
- Jia Jia Chan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
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11
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Ehrkamp A, Herrmann C, Stoll R, Heumann R. Ras and rheb signaling in survival and cell death. Cancers (Basel) 2013; 5:639-61. [PMID: 24216995 PMCID: PMC3730321 DOI: 10.3390/cancers5020639] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/08/2013] [Accepted: 05/17/2013] [Indexed: 12/11/2022] Open
Abstract
One of the most obvious hallmarks of cancer is uncontrolled proliferation of cells partly due to independence of growth factor supply. A major component of mitogenic signaling is Ras, a small GTPase. It was the first identified human protooncogene and is known since more than three decades to promote cellular proliferation and growth. Ras was shown to support growth factor-independent survival during development and to protect from chemical or mechanical lesion-induced neuronal degeneration in postmitotic neurons. In contrast, for specific patho-physiological cases and cellular systems it has been shown that Ras may also promote cell death. Proteins from the Ras association family (Rassf, especially Rassf1 and Rassf5) are tumor suppressors that are activated by Ras-GTP, triggering apoptosis via e.g., activation of mammalian sterile 20-like (MST1) kinase. In contrast to Ras, their expression is suppressed in many types of tumours, which makes Rassf proteins an exciting model for understanding the divergent effects of Ras activity. It seems likely that the outcome of Ras signaling depends on the balance between the activation of its various downstream effectors, thus determining cellular fate towards either proliferation or apoptosis. Ras homologue enriched in brain (Rheb) is a protein from the Ras superfamily that is also known to promote proliferation, growth, and regeneration through the mammalian target of rapamycin (mTor) pathway. However, recent evidences indicate that the Rheb-mTor pathway may switch its function from a pro-growth into a cell death pathway, depending on the cellular situation. In contrast to Ras signaling, for Rheb, the cellular context is likely to modulate the whole Rheb-mTor pathway towards cellular death or survival, respectively.
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Affiliation(s)
- Anja Ehrkamp
- Molecular Neurobiochemistry, Ruhr University of Bochum, 44780 Bochum, Germany; E-Mail:
| | - Christian Herrmann
- Department of Physical Chemistry1, Protein Interaction, Ruhr University of Bochum, 44780 Bochum, Germany; E-Mail:
| | - Raphael Stoll
- Biomolecular NMR, Ruhr University of Bochum, 44780 Bochum, Germany; E-Mail:
| | - Rolf Heumann
- Molecular Neurobiochemistry, Ruhr University of Bochum, 44780 Bochum, Germany; E-Mail:
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12
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Makbul C, Constantinescu Aruxandei D, Hofmann E, Schwarz D, Wolf E, Herrmann C. Structural and Thermodynamic Characterization of Nore1-SARAH: A Small, Helical Module Important in Signal Transduction Networks. Biochemistry 2013; 52:1045-54. [DOI: 10.1021/bi3014642] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Cihan Makbul
- Ruhr University, Department of Physical Chemistry I, Protein Interactions, Universitätsstrasse
150, 44780 Bochum, Germany
| | - Diana Constantinescu Aruxandei
- Ruhr University, Department of Physical Chemistry I, Protein Interactions, Universitätsstrasse
150, 44780 Bochum, Germany
| | - Eckhard Hofmann
- Ruhr University, Department of Biophysics,
Protein Crystallography, Universitätsstrasse
150, 44780 Bochum, Germany
| | - Daniel Schwarz
- Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227
Dortmund, Germany
| | - Eva Wolf
- Ludwig-Maximilians-University Munich, Department of Physiological Chemistry, Adolf
Butenandt Institute, Butenandtstrasse 5, 81377 Munich, Germany
| | - Christian Herrmann
- Ruhr University, Department of Physical Chemistry I, Protein Interactions, Universitätsstrasse
150, 44780 Bochum, Germany
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13
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Holzapfel G, Buhrman G, Mattos C. Shift in the equilibrium between on and off states of the allosteric switch in Ras-GppNHp affected by small molecules and bulk solvent composition. Biochemistry 2012; 51:6114-26. [PMID: 22845804 DOI: 10.1021/bi300509j] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Ras GTPase cycles between its active GTP-bound form promoted by GEFs and its inactive GDP-bound form promoted by GAPs to affect the control of various cellular functions. It is becoming increasingly apparent that subtle regulation of the GTP-bound active state may occur through promotion of substates mediated by an allosteric switch mechanism that induces a disorder to order transition in switch II upon ligand binding at an allosteric site. We show with high-resolution structures that calcium acetate and either dithioerythritol (DTE) or dithiothreitol (DTT) soaked into H-Ras-GppNHp crystals in the presence of a moderate amount of poly(ethylene glycol) (PEG) can selectively shift the equilibrium to the "on" state, where the active site appears to be poised for catalysis (calcium acetate), or to what we call the "ordered off" state, which is associated with an anticatalytic conformation (DTE or DTT). We also show that the equilibrium is reversible in our crystals and dependent on the nature of the small molecule present. Calcium acetate binding in the allosteric site stabilizes the conformation observed in the H-Ras-GppNHp/NOR1A complex, and PEG, DTE, and DTT stabilize the anticatalytic conformation observed in the complex between the Ras homologue Ran and Importin-β. The small molecules are therefore selecting biologically relevant conformations in the crystal that are sampled by the disordered switch II in the uncomplexed GTP-bound form of H-Ras. In the presence of a large amount of PEG, the ordered off conformation predominates, whereas in solution, in the absence of PEG, switch regions appear to remain disordered in what we call the off state, unable to bind DTE.
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Affiliation(s)
- Genevieve Holzapfel
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
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Fernandes MS, Carneiro F, Oliveira C, Seruca R. Colorectal cancer and RASSF family--a special emphasis on RASSF1A. Int J Cancer 2012; 132:251-8. [PMID: 22733432 DOI: 10.1002/ijc.27696] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 05/23/2012] [Accepted: 06/11/2012] [Indexed: 12/14/2022]
Abstract
The RAS-association domain family, commonly referred to as RASSF, is a family of 10 members (RASSF1-10) implicated in a variety of key biological processes, including cell cycle regulation, apoptosis and microtubule stability. Furthermore, RASSFs have been implicated in tumorigenesis and several family members are now thought to be tumor suppressors. As opposed to the KRAS oncogene, for which mutational activation is frequent in colorectal cancer (CRC), RASSFs are found to be silenced mainly by aberrant promoter methylation. In particular, RASSF1A, RASSF2 and RASSF5 methylation has been associated with CRC development, though the mechanisms of action remain poorly understood. This review focus on the current knowledge of RASSF inactivation in CRC, particularly RASSF1A, and on the implications RASSFs may have as potential biomarkers and for the development of new targeted therapies for CRC.
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Affiliation(s)
- Maria Sofia Fernandes
- Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal
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15
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Hippo and rassf1a Pathways: A Growing Affair. Mol Biol Int 2012; 2012:307628. [PMID: 22830020 PMCID: PMC3399428 DOI: 10.1155/2012/307628] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 05/18/2012] [Indexed: 01/15/2023] Open
Abstract
First discovered in Drosophila, the Hippo pathway regulates the size and shape of organ development. Its discovery and study have helped to address longstanding questions in developmental biology. Central to this pathway is a kinase cascade leading from the tumor suppressor Hippo (Mst1 and Mst2 in mammals) to the Yki protein (YAP and TAZ in mammals), a transcriptional coactivator of target genes involved in cell proliferation, survival, and apoptosis. A dysfunction of the Hippo pathway activity is frequently detected in human cancers. Recent studies have highlighted that the Hippo pathway may play an important role in tissue homoeostasis through the regulation of stem cells, cell differentiation, and tissue regeneration. Recently, the impact of RASSF proteins on Hippo signaling potentiating its proapoptotic activity has been addressed, thus, providing further evidence for Hippo's key role in mammalian tumorigenesis as well as other important diseases.
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Gordon M, El-Kalla M, Baksh S. RASSF1 Polymorphisms in Cancer. Mol Biol Int 2012; 2012:365213. [PMID: 22701175 PMCID: PMC3371342 DOI: 10.1155/2012/365213] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 03/01/2012] [Indexed: 12/29/2022] Open
Abstract
Ras association domain family 1A (RASSF1A) is one of the most epigenetically silenced elements in human cancers. Localized on chromosome 3, it has been demonstrated to be a bone fide tumor suppressor influencing cell cycle events, microtubule stability, apoptosis, and autophagy. Although it is epigenetically silenced by promoter-specific methylation in cancers, several somatic nucleotide changes (polymorphisms) have been identified in RASSF1A in tissues from cancer patients. We speculate that both nucleotide changes and epigenetic silencing result in loss of the RASSF1A tumor suppressor function and the appearance of enhanced growth. This paper will summarize what is known about the origin of these polymorphisms and how they have helped us understand the biological role of RASSF1A.
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Affiliation(s)
- Marilyn Gordon
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, 3-055 Katz Group Centre for Pharmacy and Health Research, 113 Street 87 Avenue, Edmonton, AB, Canada T6G 2E1
- Women and Children's Health Research Institute, University of Alberta, 4-081 Edmonton Clinic Health Academy, 11405-87 Avenue, Edmonton, AB, Canada T6G 1C9
| | - Mohamed El-Kalla
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, 3-055 Katz Group Centre for Pharmacy and Health Research, 113 Street 87 Avenue, Edmonton, AB, Canada T6G 2E1
- Women and Children's Health Research Institute, University of Alberta, 4-081 Edmonton Clinic Health Academy, 11405-87 Avenue, Edmonton, AB, Canada T6G 1C9
| | - Shairaz Baksh
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, 3-055 Katz Group Centre for Pharmacy and Health Research, 113 Street 87 Avenue, Edmonton, AB, Canada T6G 2E1
- Women and Children's Health Research Institute, University of Alberta, 4-081 Edmonton Clinic Health Academy, 11405-87 Avenue, Edmonton, AB, Canada T6G 1C9
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17
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The SARAH Domain of RASSF1A and Its Tumor Suppressor Function. Mol Biol Int 2012; 2012:196715. [PMID: 22577552 PMCID: PMC3337622 DOI: 10.1155/2012/196715] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/01/2012] [Accepted: 02/02/2012] [Indexed: 11/17/2022] Open
Abstract
The Ras association domain family 1A (RASSF1A) tumor suppressor encodes a Sav-RASSF-Hpo domain (SARAH), which is an interaction domain characterized by hWW45 (dSAV) and MST1/2 (dHpo). In our study, the interaction between RASSF1A and RASSF1C with MST1 and MST2 was demonstrated and it was shown that this interaction depends on the SARAH domain. SARAH domain-deleted RASSF1A had a similar growth-reducing effect as full-length RASSF1A and inhibited anchorage independent growth of the lung cancer cell lines A549 significantly. In cancer cells expressing the SARAH deleted form of RASSF1A, reduced mitotic rates (P = 0.001) with abnormal metaphases (P < 0.001) were observed and a significantly increased rate of apoptosis was found (P = 0.006) compared to full-length RASSF1A. Although the association with microtubules and their stabilization was unaffected, mitotic spindle formation was altered by deletion of the SARAH domain of RASSF1A. In summary, our results suggest that the SARAH domain plays an important role in regulating the function of RASSF1A.
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Yuan H, Upadhyay G, Yin Y, Kopelovich L, Glazer RI. Stem cell antigen-1 deficiency enhances the chemopreventive effect of peroxisome proliferator-activated receptorγ activation. Cancer Prev Res (Phila) 2012; 5:51-60. [PMID: 21955520 PMCID: PMC3252486 DOI: 10.1158/1940-6207.capr-11-0256] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Stem cell antigen-1 (Sca-1, Ly6A) is a glycerophosphatidylinositol (GPI)-anchored protein that was identified as a murine marker of bone marrow stem cells. Although Sca-1 is widely used to enrich for stem and progenitor cells in various tissues, little is known about its function and associated signaling pathways in normal and malignant cells. Here, we report that the absence of Sca-1 in the mammary gland resulted in higher levels of PPARγ and PTEN, and a reduction of pSer84PPARγ, pERK1/2, and PPARδ. This phenotype correlated with markedly increased sensitivity of Sca-1 null mice to PPARγ agonist GW7845 and insensitivity to PPARδ agonist GW501516. Reduction of Sca-1 expression in mammary tumor cells by RNA interference resulted in a phenotype similar to the Sca-1 deficient mammary gland, as evidenced by increased PPARγ expression and transcriptional activity, resulting in part from a lesser susceptibility to proteasomal degradation. These data implicate Sca-1 as a negative regulator of the tumor suppressor effects of PPARγ.
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Affiliation(s)
- Hongyan Yuan
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia
| | - Geeta Upadhyay
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia
| | - Yuzhi Yin
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia
| | - Levy Kopelovich
- Chemoprevention Agent Development Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland
| | - Robert I. Glazer
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia
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PPARgamma and PPARdelta as Modulators of Neoplasia and Cell Fate. PPAR Res 2011; 2008:247379. [PMID: 18566686 PMCID: PMC2430014 DOI: 10.1155/2008/247379] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 05/22/2008] [Indexed: 12/25/2022] Open
Abstract
PPARγ and PPARδ agonists represent unique classes of drugs that act through their ability to modulate gene transcription associated with intermediary metabolism, differentiation, tumor suppression, and in some instances proliferation and cell adhesion. PPARγ agonists are used by millions of people each year to treat type 2 diabetes but may also find additional utility as relatively nontoxic potentiators of chemotherapy. PPARδ agonists produce complex actions as shown by their tumor promoting effects in rodents and their cholesterol-lowering action in dyslipidemias. There is now emerging evidence that PPARs regulate tumor suppressor genes and developmental pathways associated with transformation and cell fate determination. This review discusses the role of PPARγ and PPARδ agonists as modulators of these processes.
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20
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Shinmura K, Tao H, Nagura K, Goto M, Matsuura S, Mochizuki T, Suzuki K, Tanahashi M, Niwa H, Ogawa H, Sugimura H. Suppression of hydroxyurea-induced centrosome amplification by NORE1A and down-regulation of NORE1A mRNA expression in non-small cell lung carcinoma. Lung Cancer 2011; 71:19-27. [PMID: 20434789 DOI: 10.1016/j.lungcan.2010.04.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 04/01/2010] [Accepted: 04/02/2010] [Indexed: 02/02/2023]
Abstract
The candidate tumor suppressor NORE1A is a nucleocytoplasmic shuttling protein, and although a fraction of the NORE1A in cells is localized to their centrosomes, the role of centrosomal NORE1A has not been elucidated. In this study we investigated the role of NORE1A in the numerical integrity of centrosomes and chromosome stability in lung cancer cells. Exposure of p53-deficient H1299 lung cancer cell line to hydroxyurea (HU) resulted in abnormal centrosome amplification (to 3 or more centrosomes per cell) as determined by immunofluorescence analysis with anti-γ-tubulin antibody, and forced expression of wild-type NORE1A partially suppressed the centrosome amplification. The nuclear export signal (NES) mutant (L377A/L384A) of NORE1A did not localize to centrosomes and did not suppress the centrosome amplification induced by HU. Fluorescence in situ hybridization analyses with probes specific for chromosomes 2 and 16 showed that wild-type NORE1A, but not NES-mutant NORE1A, suppressed chromosome instability in HU-exposed H1299 cells that was likely to have resulted from centrosome amplification. We next examined the status of NORE1A mRNA expression in non-small cell lung carcinoma (NSCLC) and detected down-regulation of NORE1A mRNA expression in 25 (49%) of 51 primary NSCLCs by quantitative real-time-polymerase chain reaction analysis. These results suggest that NORE1A has activity that suppresses the centrosome amplification induced by HU and that NORE1A mRNA down-regulation is one of the common gene abnormalities in NSCLCs, both of which imply a key preventive role of NORE1A against the carcinogenesis of NSCLC.
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Affiliation(s)
- Kazuya Shinmura
- 1st Department of Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu 431-3192, Shizuoka, Japan
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Dal-Bo M, Del Giudice I, Bomben R, Capello D, Bertoni F, Forconi F, Laurenti L, Rossi D, Zucchetto A, Pozzato G, Marasca R, Efremov DG, Guarini A, Del Poeta G, Foà R, Gaidano G, Gattei V. B-cell receptor, clinical course and prognosis in chronic lymphocytic leukaemia: the growing saga of the IGHV3 subgroup gene usage. Br J Haematol 2011; 153:3-14. [PMID: 21303354 DOI: 10.1111/j.1365-2141.2010.08440.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The immunoglobulin heavy chain variable gene (IGHV) mutational status has been recognized as an important predictor of prognosis in chronic lymphocytic leukaemia (CLL) since 1999. More recently, other features of the B-cell receptor, such as stereotypy, have been identified as capable of refining the prognostic potential of IGHV status in the clinical assessment of CLL patients. In this context, different genes belonging to the IGHV3 subgroup, the most frequently used subgroup in CLL, have been shown to denote disease subsets that either display a bad prognosis (i.e. IGHV3-21, IGHV3-23) or are associated with particularly good clinical outcomes, including a highly stable/indolent clinical course, even prone to spontaneous regression (i.e. IGHV3-72, IGHV3-30). The present review focuses on the molecular and biological features of CLL-expressing specific genes belonging to the IGHV3 subgroup that are known to mark disease subsets with completely different clinical courses, and may be possibly related to CLL pathogenesis via antigen and/or superantigen involvement.
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Affiliation(s)
- Michele Dal-Bo
- Department of Cellular Biotechnologies and Haematology, Sapienza University, Rome, Italy
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Effects of site-directed mutagenesis of mglA on motility and swarming of Myxococcus xanthus. BMC Microbiol 2010; 10:295. [PMID: 21083931 PMCID: PMC3000849 DOI: 10.1186/1471-2180-10-295] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 11/18/2010] [Indexed: 01/31/2023] Open
Abstract
Background The mglA gene from the bacterium Myxococcus xanthus encodes a 22kDa protein related to the Ras superfamily of monomeric GTPases. MglA is required for the normal function of A-motility (adventurous), S-motility (social), fruiting body morphogenesis, and sporulation. MglA and its homologs differ from all eukaryotic and other prokaryotic GTPases because they have a threonine (Thr78) in place of the highly conserved aspartate residue of the consensus PM3 (phosphate-magnesium binding) region. To identify residues critical for MglA function or potential protein interactions, and explore the function of Thr78, the phenotypes of 18 mglA mutants were characterized. Results Nine mutants, with mutations predicted to alter residues that bind the guanine base or coordinate magnesium, did not produce detectable MglA. As expected, these mutants were mot- dev- because MglA is essential for these processes. Of the remaining nine mutants, seven showed a wild-type distribution pattern for MglA but fell into two categories with regard to function. Five of the seven mutants exhibited mild phenotypes, but two mutants, T78D and P80A, abolished motility and development. The localization pattern of MglA was abolished in two mutants that were mot- spo- and dev-. These two mutants were predicted to alter surface residues at Asp52 and Thr54, which suggests that these residues are critical for proper localization and may define a protein interaction site. Improving the consensus match with Ras at Thr78 abolished function of MglA. Only the conservative serine substitution was tolerated at this position. Merodiploid constructs revealed that a subset of alleles, including mglAD52A, were dominant and also illustrated that changing the balance of MglA and its co-transcribed partner, MglB, affects A-motility. Conclusion Our results suggest that GTP binding is critical for stability of MglA because MglA does not accumulate in mutants that cannot bind GTP. The threonine in PM3 of MglA proteins represents a novel modification of the highly conserved GTPase consensus at this position. The requirement for a hydroxyl group at this position may indicate that MglA is subject to modification under certain conditions. Proper localization of MglA is critical for both motility and development and likely involves protein interactions mediated by residues Asp52 and Thr54.
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El-Kalla M, Onyskiw C, Baksh S. Functional importance of RASSF1A microtubule localization and polymorphisms. Oncogene 2010; 29:5729-40. [PMID: 20697344 DOI: 10.1038/onc.2010.316] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Ras association domain family protein 1A (RASSF1A) is one of the more heavily methylated genes in human cancers. In addition to promoter-specific methylation, RASSF1A polymorphisms have been identified in cancer patients. RASSF1A is a tumor suppressor protein involved in death receptor-dependent apoptosis and it is localized to microtubules. Currently, the biological importance of RASSF1A microtubule localization and the functional consequences of RASSF1A polymorphisms is not understood. In this study, we have investigated both RASSF1A microtubule association and polymorphisms. Loss of RASSF1A microtubule association resulted in the nuclear appearance of RASSF1A and the loss of association with α-, γ- and β-tubulin. Moreover, the loss of microtubule localization of RASSF1A resulted in enhanced tumor-promoting potential, as determined by a xenograft transplantation model in nude mice. It is surprising that, several RASSF1A polymorphisms also lost the ability to associate with α-, γ- and β-tubulin and lost the ability to prevent tumor formation in a xenograft nude mouse model when compared with wild-type RASSF1A. Our results demonstrate a role for RASSF1A microtubule localization in eliciting its tumor suppressor function. In addition, some RASSF1A polymorphisms lack the tumor suppressor function of RASSF1A and, if present in patients, may be tumorigenic.
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Affiliation(s)
- M El-Kalla
- Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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24
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Bee C, Moshnikova A, Mellor CD, Molloy JE, Koryakina Y, Stieglitz B, Khokhlatchev A, Herrmann C. Growth and tumor suppressor NORE1A is a regulatory node between Ras signaling and microtubule nucleation. J Biol Chem 2010; 285:16258-66. [PMID: 20339001 PMCID: PMC2871493 DOI: 10.1074/jbc.m109.081562] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 03/23/2010] [Indexed: 12/31/2022] Open
Abstract
NORE1A is a Ras-binding protein that belongs to a group of tumor suppressors known as the Ras association domain family. Their growth- and tumor-suppressive function is assumed to be dependent on association with the microtubule cytoskeleton. However, a detailed understanding of this interplay is still missing. Here, we show that NORE1A directly interacts with tubulin and is capable of nucleating microtubules. Strikingly, the ability to stimulate nucleation is regulated in a dual specific way either via phosphorylation of NORE1A within the Ras-binding domain by Aurora A kinase or via binding to activated Ras. We also demonstrate that NORE1A mediates a negative effect of activated Ras on microtubule nucleation. On the basis of our results, we propose a novel regulatory network composed of the tumor suppressor NORE1A, the mitotic kinase Aurora A, the small GTPase Ras, and the microtubule cytoskeleton.
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Affiliation(s)
- Christine Bee
- From the Department of Chemistry, Physical Chemistry 1, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | | | - Christopher D. Mellor
- the Medical Research Council National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
| | - Justin E. Molloy
- the Medical Research Council National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
| | - Yulia Koryakina
- Microbiology, University of Virginia Health Science Center, Charlottesville, Virginia 22908, and
| | - Benjamin Stieglitz
- the Medical Research Council National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
| | | | - Christian Herrmann
- From the Department of Chemistry, Physical Chemistry 1, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Kumari G, Singhal P, Suryaraja R, Mahalingam S. Functional Interaction of the Ras Effector RASSF5 with the Tyrosine Kinase Lck: Critical Role in Nucleocytoplasmic Transport and Cell Cycle Regulation. J Mol Biol 2010; 397:89-109. [DOI: 10.1016/j.jmb.2010.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 12/28/2009] [Accepted: 01/05/2010] [Indexed: 10/20/2022]
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26
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Bomben R, Dal-Bo M, Benedetti D, Capello D, Forconi F, Marconi D, Bertoni F, Maffei R, Laurenti L, Rossi D, Del Principe MI, Luciano F, Sozzi E, Cattarossi I, Zucchetto A, Rossi FM, Bulian P, Zucca E, Nicoloso MS, Degan M, Marasca R, Efremov DG, Del Poeta G, Gaidano G, Gattei V. Expression of mutated IGHV3-23 genes in chronic lymphocytic leukemia identifies a disease subset with peculiar clinical and biological features. Clin Cancer Res 2010; 16:620-8. [PMID: 20068100 DOI: 10.1158/1078-0432.ccr-09-1638] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE B-cell chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease whose outcome can be foreseen by investigating the mutational status of immunoglobulin heavy chain variable (IGHV) genes. Moreover, a different prognosis was reported for CLL expressing specific IGHV genes in the context or not of stereotyped B-cell receptors. Here we investigated novel associations between usage of specific IGHV genes and clinical features in CLL. EXPERIMENTAL DESIGN Among 1,426 CLL-specific IG-rearrangements, stereotyped B-cell receptor clusters never utilized the IGHV3-23 gene. Given this notion, this study was aimed at characterizing the IGHV3-23 gene in CLL, and identifying the properties of IGHV3-23-expressing CLL. RESULTS IGHV3-23 was the second most frequently used (134 of 1,426) and usually mutated (M; 109 of 134) IGHV gene in our CLL series. In the vast majority of M IGHV3-23 sequences, the configuration of the 13 amino acids involved in superantigen recognition was consistent with superantigen binding. Clinically, M IGHV3-23 CLL had shorter time-to-treatment than other M non-IGHV3-23 CLL, and multivariate analyses selected IGHV3-23 gene usage, Rai staging, and chromosomal abnormalities as independent prognosticators for M CLL. Compared with M non-IGHV3-23 CLL, the gene expression profile of M IGHV3-23 CLL was deprived in genes, including the growth/tumor suppressor genes PDCD4, TIA1, and RASSF5, whose downregulation is under control of miR-15a and miR-16-1. Accordingly, relatively higher levels of miR-15a and miR-16-1 were found in M IGHV3-23 compared with M non-IGHV3-23 CLL. CONCLUSIONS Altogether, expression of the IGHV3-23 gene characterizes a CLL subset with distinct clinical and biological features.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Cohort Studies
- Diagnosis, Differential
- Gene Expression Profiling
- Gene Expression Regulation, Leukemic
- Gene Rearrangement/physiology
- Genes, Immunoglobulin Heavy Chain/genetics
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/classification
- Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis
- Leukemia, Lymphocytic, Chronic, B-Cell/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- MicroRNAs/genetics
- Middle Aged
- Mutant Proteins/genetics
- Neoplasm Staging
- Prognosis
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Affiliation(s)
- Riccardo Bomben
- Clinical and Experimental Onco-Hematology Unit, Centro di Riferimento Oncologico, I.R.C.C.S., Aviano (PN), Italy
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The N-terminal RASSF family: a new group of Ras-association-domain-containing proteins, with emerging links to cancer formation. Biochem J 2009; 425:303-11. [PMID: 20025613 DOI: 10.1042/bj20091318] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The RASSF (Ras-association domain family) has recently gained several new members and now contains ten proteins (RASSF1-10), several of which are potential tumour suppressors. The family can be split into two groups, the classical RASSF proteins (RASSF1-6) and the four recently added N-terminal RASSF proteins (RASSF7-10). The N-terminal RASSF proteins have a number of differences from the classical RASSF members and represent a newly defined set of potential Ras effectors. They have been linked to key biological processes, including cell death, proliferation, microtubule stability, promoter methylation, vesicle trafficking and response to hypoxia. Two members of the N-terminal RASSF family have also been highlighted as potential tumour suppressors. The present review will summarize what is known about the N-terminal RASSF proteins, addressing their function and possible links to cancer formation. It will also compare the N-terminal RASSF proteins with the classical RASSF proteins and ask whether the N-terminal RASSF proteins should be considered as genuine members or imposters in the RASSF family.
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Richter AM, Pfeifer GP, Dammann RH. The RASSF proteins in cancer; from epigenetic silencing to functional characterization. Biochim Biophys Acta Rev Cancer 2009; 1796:114-28. [DOI: 10.1016/j.bbcan.2009.03.004] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Revised: 03/19/2009] [Accepted: 03/21/2009] [Indexed: 01/22/2023]
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Ras pathway activation in hepatocellular carcinoma and anti-tumoral effect of combined sorafenib and rapamycin in vivo. J Hepatol 2009; 51:725-33. [PMID: 19665249 PMCID: PMC2970800 DOI: 10.1016/j.jhep.2009.03.028] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/04/2009] [Accepted: 03/16/2009] [Indexed: 02/08/2023]
Abstract
BACKGROUND/AIMS The success of sorafenib in the treatment of advanced hepatocellular carcinoma (HCC) has focused interest on the role of Ras signaling in this malignancy. We investigated the molecular alterations of the Ras pathway in HCC and the antineoplastic effects of sorafenib in combination with rapamycin, an inhibitor of mTOR pathway, in experimental models. METHODS Gene expression (qRT-PCR, oligonucleotide microarray), DNA copy number changes (SNP-array), methylation of tumor suppressor genes (methylation-specific PCR) and protein activation (immunohistochemistry) were analysed in 351 samples. Anti-tumoral effects of combined therapy targeting the Ras and mTOR pathways were evaluated in cell lines and HCC xenografts. RESULTS Different mechanisms accounted for Ras pathway activation in HCC. H-ras was up-regulated during different steps of hepatocarcinogenesis. B-raf was overexpressed in advanced tumors and its expression was associated with genomic amplification. Partial methylation of RASSF1A and NORE1A was detected in 89% and 44% of tumors respectively, and complete methylation was found in 11 and 4% of HCCs. Activation of the pathway (pERK immunostaining) was identified in 10.3% of HCC. Blockade of Ras and mTOR pathways with sorafenib and rapamycin reduced cell proliferation and induced apoptosis in cell lines. In vivo, the combination of both compounds enhanced tumor necrosis and ulceration when compared with sorafenib alone. CONCLUSIONS Ras activation results from several molecular alterations, such as methylation of tumor suppressors and amplification of oncogenes (B-raf). Sorafenib blocks signaling and synergizes with rapamycin in vivo, preventing tumor progression. These data provide the rationale for testing this combination in clinical studies.
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Yin Y, Yuan H, Zeng X, Kopelovich L, Glazer RI. Inhibition of peroxisome proliferator-activated receptor gamma increases estrogen receptor-dependent tumor specification. Cancer Res 2009; 69:687-94. [PMID: 19147585 DOI: 10.1158/0008-5472.can-08-2446] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that regulates gene transcription associated with intermediary metabolism, adipocyte differentiation, and tumor suppression and proliferation. To understand the role of PPARgamma in tumorigenesis, transgenic mice were generated with mammary gland-directed expression of the dominant-negative transgene Pax8PPARgamma. Transgenic mice were phenotypically indistinguishable from wild-type (WT) mice, but mammary epithelial cells expressed a greater percentage of CD29(hi)/CD24(neg), CK5(+), and double-positive CK14/CK18 cells. These changes correlated with reduced PTEN and increased Ras and extracellular signal-regulated kinase (ERK) and AKT activation. Although spontaneous tumorigenesis did not occur, transgenic animals were highly susceptible to progestin/7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis, which in contrast to WT mice resulted in a high tumor multiplicity and, most importantly, in the appearance of predominantly estrogen receptor alpha-positive (ER(+)) ductal adenocarcinomas. Tumors expressed a similar PTEN(lo)/pERK(hi)/pAKT(hi) phenotype as mammary epithelium and exhibited high activation of estrogen response element-dependent reporter gene activity. Tumorigenesis in MMTV-Pax8PPARgamma mice was insensitive to the chemopreventive effect of a PPARgamma agonist but was profoundly inhibited by the ER antagonist fulvestrant. These results reveal important new insights into the previously unrecognized role of PPARgamma in the specification of mammary lineage and the development of ER(+) tumors.
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Affiliation(s)
- Yuzhi Yin
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University, Washington, District of Columbia 20007, USA
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Macheiner D, Gauglhofer C, Rodgarkia-Dara C, Grusch M, Brachner A, Bichler C, Kandioler D, Sutterlüty H, Mikulits W, Schulte-Hermann R, Grasl-Kraupp B. NORE1B is a putative tumor suppressor in hepatocarcinogenesis and may act via RASSF1A. Cancer Res 2009; 69:235-42. [PMID: 19118008 DOI: 10.1158/0008-5472.can-08-2144] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recently, we found epigenetic silencing of the Ras effector genes NORE1B and/or RASSF1A in 97% of the hepatocellular carcinoma (HCC) investigated. This is strong evidence that the two genes are of major significance in hepatocarcinogenesis. Although RASSF1A serves as a tumor suppressor gene, the functions of NORE1B are largely unknown. Here, we studied the role of NORE1B for growth and transformation of cells. To understand the molecular mechanisms of action of the gene, we used the wild-type form and deletion mutants without the NH(2) terminus and CENTRAL domain, the Ras association (RA) domain, or the COOH-terminal SARAH-domain. Intact RA and SARAH-domains were found to be necessary for NORE1B (a) to increase the G(0)-G(1) fraction in hepatoma cells, (b) to suppress c-Myc/Ha-Ras-induced cell transformation, and (c) to interact closely with RASSF1A, as determined with fluorescence resonance energy transfer. In further studies, cell cycle delay by NORE1B was equally effective in hepatocyte cell lines with wild-type or mutant Ras suggesting that NORE1B does not interact with either Ras. In conclusion, NORE1B suppresses replication and transformation of cells as effectively as RASSF1A and thus is a putative tumor suppressor gene. NORE1B interacts physically with RASSF1A and functional loss of one of the interacting partners may lead to uncontrolled growth and transformation of hepatocytes. This may explain the frequent epigenetic silencing of NORE1B and/or RASSF1A in HCC.
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Affiliation(s)
- Doris Macheiner
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschkegasse 8a, Vienna, Austria
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Kuznetsov S, Khokhlatchev AV. The growth and tumor suppressors NORE1A and RASSF1A are targets for calpain-mediated proteolysis. PLoS One 2008; 3:e3997. [PMID: 19098985 PMCID: PMC2602596 DOI: 10.1371/journal.pone.0003997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Accepted: 11/23/2008] [Indexed: 11/25/2022] Open
Abstract
Background NORE1A and RASSF1A are growth and tumour suppressors inactivated in a variety of cancers. Methylation of NORE1A and RASSF1A promoters is the predominant mechanism for downregulation of these proteins; however, other mechanisms are likely to exist. Methodology/Principal Findings Here we describe a proteolysis of NORE1A and RASSF1A by calpains as alternative mechanism of their downregulation. Extracts of H358 cell line, a human bronchoalveolar carcinoma, and H460, a large cell carcinoma, were capable of proteolysis of NORE1A protein in the calpain-dependent manner. Likewise, RASSF1A tumor suppressor was proteolyzed by the H358 cell extract. Addition of calpain inhibitor to H358 and H460 cells growing in tissue culture resulted in re-expression of endogenous NORE1A. A survey of 10 human lung tumours revealed that three of them contain an activity capable of inducing NORE1A degradation. Conclusions/Significance Thus, degradation by calpains is a novel mechanism for downregulation of NORE1A and RASSF1A proteins and might be the mechanism allowing cancer cells to escape growth suppression.
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Affiliation(s)
- Sergey Kuznetsov
- Department of Physics, University of Rhode Island, East Hall, Kingston, Rhode Island, United States of America
| | - Andrei V. Khokhlatchev
- Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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Stieglitz B, Bee C, Schwarz D, Yildiz O, Moshnikova A, Khokhlatchev A, Herrmann C. Novel type of Ras effector interaction established between tumour suppressor NORE1A and Ras switch II. EMBO J 2008; 27:1995-2005. [PMID: 18596699 DOI: 10.1038/emboj.2008.125] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 06/04/2008] [Indexed: 12/30/2022] Open
Abstract
A class of putative Ras effectors called Ras association domain family (RASSF) represents non-enzymatic adaptors that were shown to be important in tumour suppression. RASSF5, a member of this family, exists in two splice variants known as NORE1A and RAPL. Both of them are involved in distinct cellular pathways triggered by Ras and Rap, respectively. Here we describe the crystal structure of Ras in complex with the Ras binding domain (RBD) of NORE1A/RAPL. All Ras effectors share a common topology in their RBD creating an interface with the switch I region of Ras, whereas NORE1A/RAPL RBD reveals additional structural elements forming a unique Ras switch II binding site. Consequently, the contact area of NORE1A is extended as compared with other Ras effectors. We demonstrate that the enlarged interface provides a rationale for an exceptionally long lifetime of the complex. This is a specific attribute characterizing the effector function of NORE1A/RAPL as adaptors, in contrast to classical enzymatic effectors such as Raf, RalGDS or PI3K, which are known to form highly dynamic short-lived complexes with Ras.
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Affiliation(s)
- Benjamin Stieglitz
- Physikalische Chemie 1, Fakultät für Chemie und Biochemie, Ruhr-Universität Bochum, Bochum, Germany
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Moshnikova A, Kuznetsov S, Khokhlatchev AV. Interaction of the growth and tumour suppressor NORE1A with microtubules is not required for its growth-suppressive function. BMC Res Notes 2008; 1:13. [PMID: 18710533 PMCID: PMC2518271 DOI: 10.1186/1756-0500-1-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2008] [Accepted: 05/15/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The NORE1 protein was identified in a yeast two-hybrid screen as a Ras effector that binds Ras protein in a GTP-dependent manner. NORE1A is a growth and tumour suppressor that is inactivated in a variety of cancers. In transformed human cells, both full-length NORE1A protein and its effector domain alone (amino acids 191-363) are localized to microtubules and centrosomes. However, the mechanism by which NORE1A associates with these cytoskeletal elements is not known; furthermore, whether centrosomally-associated or microtubule-associated NORE1A suppresses tumour cell growth has not been yet established. FINDINGS We have shown that purified NORE1A fails to bind to microtubules in vitro suggesting that other protein(s) mediate NORE1A-microtubule association. Using mass-spectrometry, we identified the Microtubule-Associated Protein 1B (MAP1B) and its homologue C19ORF5 as NORE1A interaction partners. Suppression of C19ORF5 expression by RNA interference (RNAi) and immunodepletion of C19ORF5 protein from cell extracts showed that binding of NORE1A to microtubules is not dependent on C19ORF5. Conversely, RNAi suppression of MAP1B revealed that MAP1B is required for association of NORE1A with microtubules. RNAi-mediated depletion of C19ORF5 or MAP1B did not prevent centrosomal localization of NORE1A. Moreover, the depletion of C19ORF5 or MAP1B did not prevent NORE1A's ability to suppress tumour cell growth. CONCLUSION The interaction of NORE1A with microtubules is mediated by MAP1B, but not C19ORF5 protein. Interaction of NORE1A with centrosomes is not dependent on C19ORF5 or MAP1B, and appears to involve a different mechanism independent of binding to microtubules. The NORE1A microtubular localization is not required for growth suppression.
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Affiliation(s)
- Anna Moshnikova
- Department of Pathology, University of Virginia, PO Box 800904, Charlottesville, VA 22908-0904, USA.
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Geli J, Kogner P, Lanner F, Natalishvili N, Juhlin C, Kiss N, Clark GJ, Ekström TJ, Farnebo F, Larsson C. Assessment of NORE1A
as a putative tumor suppressor in human neuroblastoma. Int J Cancer 2008; 123:389-394. [DOI: 10.1002/ijc.23533] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Omerovic J, Laude AJ, Prior IA. Ras proteins: paradigms for compartmentalised and isoform-specific signalling. Cell Mol Life Sci 2007; 64:2575-89. [PMID: 17628742 PMCID: PMC2561238 DOI: 10.1007/s00018-007-7133-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Ras GTPases mediate a wide variety of cellular processes by converting a multitude of extracellular stimuli into specific biological responses including proliferation, differentiation and survival. In mammalian cells, three ras genes encode four Ras isoforms (H-Ras, K-Ras4A, K-Ras4B and N-Ras) that are highly homologous but functionally distinct. Differences between the isoforms, including their post-translational modifications and intracellular sorting, mean that Ras has emerged as an important model system of compartmentalised signalling and membrane biology. Ras isoforms in different subcellular locations are proposed to recruit distinct upstream and downstream accessory proteins and activate multiple signalling pathways. Here, we summarise data relating to isoform-specific signalling, its role in disease and the mechanisms promoting compartmentalised signalling. Further understanding of this field will reveal the role of Ras signalling in development, cellular homeostasis and cancer and may suggest new therapeutic approaches.
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Affiliation(s)
- J. Omerovic
- Physiological Laboratory, University of Liverpool, Crown St., Liverpool, L69 3BX UK
| | - A. J. Laude
- Physiological Laboratory, University of Liverpool, Crown St., Liverpool, L69 3BX UK
| | - I. A. Prior
- Physiological Laboratory, University of Liverpool, Crown St., Liverpool, L69 3BX UK
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van der Weyden L, Adams DJ. The Ras-association domain family (RASSF) members and their role in human tumourigenesis. Biochim Biophys Acta Rev Cancer 2007; 1776:58-85. [PMID: 17692468 PMCID: PMC2586335 DOI: 10.1016/j.bbcan.2007.06.003] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 06/26/2007] [Accepted: 06/26/2007] [Indexed: 12/13/2022]
Abstract
Ras proteins play a direct causal role in human cancer with activating mutations in Ras occurring in approximately 30% of tumours. Ras effectors also contribute to cancer, as mutations occur in Ras effectors, notably B-Raf and PI3-K, and drugs blocking elements of these pathways are in clinical development. In 2000, a new Ras effector was identified, RAS-association domain family 1 (RASSF1), and expression of the RASSF1A isoform of this gene is silenced in tumours by methylation of its promoter. Since methylation is reversible and demethylating agents are currently being used in clinical trials, detection of RASSF1A silencing by promoter hypermethylation has potential clinical uses in cancer diagnosis, prognosis and treatment. RASSF1A belongs to a new family of RAS effectors, of which there are currently 8 members (RASSF1-8). RASSF1-6 each contain a variable N-terminal segment followed by a Ras-association (RA) domain of the Ral-GDS/AF6 type, and a specialised coiled-coil structure known as a SARAH domain extending to the C-terminus. RASSF7-8 contain an N-terminal RA domain and a variable C-terminus. Members of the RASSF family are thought to function as tumour suppressors by regulating the cell cycle and apoptosis. This review will summarise our current knowledge of each member of the RASSF family and in particular what role they play in tumourigenesis, with a special focus on RASSF1A, whose promoter methylation is one of the most frequent alterations found in human tumours.
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Affiliation(s)
- Louise van der Weyden
- Experimental Cancer Genetics Laboratory, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton Cambridge, UK.
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Kumari G, Singhal PK, Rao MRKS, Mahalingam S. Nuclear transport of Ras-associated tumor suppressor proteins: different transport receptor binding specificities for arginine-rich nuclear targeting signals. J Mol Biol 2007; 367:1294-311. [PMID: 17320110 DOI: 10.1016/j.jmb.2007.01.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 12/28/2006] [Accepted: 01/05/2007] [Indexed: 12/30/2022]
Abstract
Ras proteins regulate a wide range of biological processes by interacting with a variety of effector proteins. In addition to the known role in tumorigensis, the activated form of Ras exhibits growth-inhibitory effects by unknown mechanisms. Several Ras effector proteins identified as mediators of apoptosis and cell-cycle arrest also exhibit properties normally associated with tumor suppressor proteins. Here, we show that Ras effector RASSF5/NORE-1 binds strongly to K-Ras but weakly to both N-Ras and H-Ras. RASSF5 was found to localize both in the nucleus and the nucleolus in contrast to other Ras effector proteins, RASSF1C and RASSF2, which are localized in the nucleus and excluded from nucleolus. A 50 amino acid residue transferable arginine-rich nucleolar localization signal (NoLS) identified in RASSF5 is capable of interacting with importin-beta and transporting the cargo into the nucleolus. Surprisingly, similar arginine-rich signals identified in RASSF1C and RASSF2 interact with importin-alpha and transport the heterologous cytoplasmic proteins to the nucleus. Interestingly, mutation of arginine residues within these nuclear targeting signals prevented interaction of Ras effector proteins with respective transport receptors and abolished their nuclear translocation. These results provide evidence for the first time that arginine-rich signals are able to recognize different nuclear import receptors and transport the RASSF proteins into distinct sub-cellular compartments. In addition, our data suggest that the nuclear localization of RASSF5 is critical for its cell growth control activity. Together, these data suggest that the transport of Ras effector superfamily proteins into the nucleus/nucleolus may play a vital role in modulating Ras-mediated cell proliferation during tumorigenesis.
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Affiliation(s)
- Gita Kumari
- Laboratory of Molecular Virology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500076, India
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