title: Melanoma associated antigen (MAGE)-A3 promotes cell proliferation and chemotherapeutic drug resistance in gastric cancer.
abstract: BACKGROUND
  Melanoma-associated antigen (MAGE)-A3 is a member of the family of cancer-testis antigens and has been found to be epigenetically regulated and aberrantly expressed in various cancer types. It has also been found that MAGE-A3 expression may correlate with an aggressive clinical course and with chemo-resistance. The objectives of this study were to assess the relationship between MAGE-A3 promoter methylation and expression and (1) gastric cancer patient survival and (2) its functional consequences in gastric cancer-derived cells.
  
  
  METHODS
  Samples from two independent gastric cancer cohorts (including matched non-malignant gastric samples) were included in this study. MAGE-A3 methylation and mRNA expression levels were determined by methylation-specific PCR (MSP) and quantitative real-time PCR (qPCR), respectively. MAGE-A3 expression was knocked down in MKN1 gastric cancer-derived cells using miRNAs. In addition, in vitro cell proliferation, colony formation, apoptosis, cell cycle, drug treatment, immunohistochemistry and Western blot assays were performed.
  
  
  RESULTS
  Clinical analysis of 223 primary patient-derived samples (ntumor = 161, nnormal = 62) showed a significant inverse correlation between MAGE-A3 promoter methylation and expression in the cancer samples (R = -0.63, p = 5.99e-19). A lower MAGE-A3 methylation level was found to be associated with a worse patient survival (HR: 1.5, 95 % CI: 1.02-2.37, p = 0.04). In addition, we found that miRNA-mediated knockdown of MAGE-A3 expression in MKN1 cells caused a reduction in its proliferation and colony forming capacities, respectively. Under stress conditions MAGE-A3 was found to regulate the expression of Bax and p21. MAGE-A3 knock down also led to an increase in Puma and Noxa expression, thus contributing to an enhanced docetaxel sensitivity in the gastric cancer-derived cells.
  
  
  CONCLUSIONS
  From our results we conclude that MAGE-A3 expression is regulated epigenetically by promoter methylation, and that its expression contributes to gastric cell proliferation and drug sensitivity. This study underscores the potential implications of MAGE-A3 as a therapeutic target and prognostic marker in gastric cancer patients.
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Chen
authors: C
authors: Xie
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.|Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.
authors: Vinod Vijay
authors: VV
authors: Subhash
authors: Department of Physiology, National University of Singapore, Singapore, Singapore.
authors: Arpita
authors: A
authors: Datta
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Natalia
authors: N
authors: Liem
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.|Centre for Quantitative Medicine, Duke-NUS Graduate Medical School, Singapore, Singapore.
authors: Shi Hui
authors: SH
authors: Tan
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Mei Shi
authors: MS
authors: Yeo
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Woei Loon
authors: WL
authors: Tan
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Vivien
authors: V
authors: Koh
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Fui Leng
authors: FL
authors: Yan
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore.
authors: Foong Ying
authors: FY
authors: Wong
authors: Departments of Pathology and General Surgery, Singapore General Hospital, Singapore, Singapore.
authors: Wai Keong
authors: WK
authors: Wong
authors: Departments of Medicine, Surgery, and Pathology, National University Health System, Singapore, Singapore.
authors: Jimmy
authors: J
authors: So
authors: Department of Medical Oncology, National Cancer Centre Singapore, Singapore, Singapore.
authors: Iain Beehuat
authors: IB
authors: Tan
authors: Department of Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, Singapore.
authors: Nisha
authors: N
authors: Padmanabhan
authors: Department of Physiology, National University of Singapore, Singapore, Singapore.|National University Cancer Institute, Singapore, Singapore.
authors: Celestial T
authors: CT
authors: Yap
authors: Department of Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore, Singapore.
authors: Patrick
authors: P
authors: Tan
authors: Centre for Quantitative Medicine, Duke-NUS Graduate Medical School, Singapore, Singapore.
authors: Liang Kee
authors: LK
authors: Goh
authors: Department of Haematology-Oncology, National University Hospital, Level 7, NUHS Tower Block, 1E, Kent Ridge Road, Singapore, 119228, Singapore. wei_peng_yong@nuhs.edu.sg.|Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore. wei_peng_yong@nuhs.edu.sg.
authors: Wei Peng
authors: WP
authors: Yong
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics; D000077143:Docetaxel; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology*; D013312:Stress, Physiological / Q000187:drug effects; D016019:Survival Analysis; D043823:Taxoids / Q000494:pharmacology; D014410:Tumor Stem Cell Assay
chemical_list: D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; C072013:MAGEA3 protein, human; D009363:Neoplasm Proteins; D043823:Taxoids; D000077143:Docetaxel
keywords: Apoptosis; Docetaxel; Gastric cancer; MAGE-A3; Methylation; Proliferation