title: GSTP1 determines cis-platinum cytotoxicity in gastric adenocarcinoma MGC803 cells: regulation by promoter methylation and extracellular regulated kinase signaling.
abstract: Detoxification mechanisms can play a pivotal role in determining tumor cell responses to platinum-based chemotherapy. Glutathione S-transferase-pi (GSTP1) belongs to a supergene family of detoxifying enzymes involved in the prevention of DNA damage and subsequent platinum resistance in numerous cancers. The role of GSTP1 in gastric cancer sensitivity to chemotherapy is, however, not known. In this study, we found that the human gastric cancer cell line MGC803 was significantly more sensitive to cis-platinum (CDDP) than the other gastric cancer lines examined (BGC823 and SGC7901). To explore the potential role of GSTP1 in drug resistance, we measured GSTP1 expression in these cells. GSTP1 mRNA and protein were not detectable in MGC803 cells; both were present in BGC823 and SGC7901 cells. GSTP1 CpG island DNA methylation was examined. We report that promoter hypermethylation was associated with the absence of GSTP1 expression in MGC803 cells. Treatment of these cells with 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, restored GSTP1 expression and suppressed sensitivity to CDDP. The selective mitogen-activated protein kinase/extracellular regulated kinase (ERK) pathway inhibitor PD98059 decreased GSTP1 expression in 5-aza-2'-deoxycytidine-treated cells. A similar decrease was observed in the BGC823 and SGC7901 cell lines, suggesting that mitogen-activated protein kinase/ERK signaling stimulates GSTP1 expression. CDDP sensitivity was also enhanced by PD98059. These observations indicate that somatic promoter hypermethylation and impaired ERK signaling are associated with decreased GSTP1 expression and CDDP sensitivity in gastric cancer cell lines. Evaluation of promoter methylation and ERK activity may be useful for predicting tumor sensitivity to platinum-based chemotherapeutics.
authors.affiliation: Department of Medical Oncology bMedical Respiratory, The First Hospital, China Medical University, Shenyang, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Qu
authors.forename: Wei
authors.initials: W
authors.lastname: Jing
authors.forename: Xuejun
authors.initials: X
authors.lastname: Hu
authors.forename: Xianghong
authors.initials: X
authors.lastname: Yang
authors.forename: Kezuo
authors.initials: K
authors.lastname: Hou
authors.forename: Yuee
authors.initials: Y
authors.lastname: Teng
authors.forename: Jingdong
authors.initials: J
authors.lastname: Zhang
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology; D000970:Antineoplastic Agents / Q000494:pharmacology; D018906:Antineoplastic Agents, Alkylating / Q000493:pharmacokinetics / Q000494:pharmacology*; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects / Q000201:enzymology; D002945:Cisplatin / Q000493:pharmacokinetics / Q000494:pharmacology*; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004790:Enzyme Induction; D015972:Gene Expression Regulation, Neoplastic; D051549:Glutathione S-Transferase pi / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008658:Inactivation, Metabolic / Q000235:genetics / Q000502:physiology; D020935:MAP Kinase Signaling System / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D013274:Stomach Neoplasms / Q000201:enzymology* / Q000473:pathology; D014158:Transcription, Genetic
chemical_list: D000970:Antineoplastic Agents; D018906:Antineoplastic Agents, Alkylating; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D000077209:Decitabine; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D020928:Mitogen-Activated Protein Kinases; D001374:Azacitidine; D002945:Cisplatin