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Epigenetic Regulation of the Homeobox Gene MSX1 Associates with Platinum-Resistant Disease in High-Grade Serous Epithelial Ovarian Cancer.

ABSTRACT: PURPOSE:Although high-grade serous ovarian cancer (HGSOC) is frequently chemoresponsive, a proportion of patients do not respond to platinum-based chemotherapy at presentation or have progression-free survival (PFS) of less than 6 months. Validated predictive biomarkers of lack of response would enable alternative treatment stratification for these patients and identify novel mechanisms of intrinsic resistance. Our aim was to identify DNA methylation biomarkers of poor response to chemotherapy and demonstrate involvement of the associated gene in platinum drug cell sensitivity. EXPERIMENTAL DESIGN:DNA methylation was investigated in independent tumor cohorts using Illumina HumanMethylation arrays and gene expression by Affymetrix arrays and qRT-PCR. The role of Msh homeobox 1 (MSX1) in drug sensitivity was investigated by gene reintroduction and siRNA knockdown of ovarian cancer cell lines. RESULTS:CpG sites at contiguous genomic locations within the MSX1 gene have significantly lower levels of methylation in independent cohorts of HGSOC patients, which recur by 6 months compared with after 12 months (P < 0.05, q < 0.05, n = 78), have poor RECIST response (P < 0.05, q < 0.05, n = 61), and are associated with PFS in an independent cohort (n = 146). A decrease in methylation at these CpG sites correlates with decreased MSX1 gene expression. MSX1 expression is associated with PFS (HR, 0.92; 95% CI, 0.85-0.99; P = 0.029; n = 309). Cisplatin-resistant ovarian cancer cell lines have reduced MSX1 expression, and MSX1 overexpression leads to cisplatin sensitization, increased apoptosis, and increased cisplatin-induced p21 expression. CONCLUSIONS:Hypomethylation of CpG sites within the MSX1 gene is associated with resistant HGSOC disease at presentation and identifies expression of MSX1 as conferring platinum drug sensitivity. Clin Cancer Res; 22(12); 3097-104. ©2016 AACR.

SUBMITTER: Bonito NA

PROVIDER: S-EPMC4849558 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Project description:PurposeOne major reason of the high mortality of epithelial ovarian cancer (EOC) is due to platinum-based chemotherapy resistance. Aberrant DNA methylation may be a potential mechanism underlying the development of platinum resistance in EOC. The purpose of this study is to discover potential aberrant DNA methylation that contributes to drug resistance.MethodsBy initially screening of 16 platinum-sensitive/resistant samples from EOC patients with reduced representation bisulfite sequencing (RRBS), the upstream region of the hMSH2 gene was discovered hypermethylated in the platinum-resistant group. The effect of hMSH2 methylation on the cellular response to cisplatin was explored by demethylation and knockdown assays in ovarian cancer cell line A2780. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry was employed to examine the methylation levels of hMSH2 upstream region in additional 40 EOC patient samples. RT-qPCR and IHC assay was used to detect the hMSH2 mRNA and protein expression in extended 150 patients.ResultsRRBS assay discovered an upstream region from -?1193 to -?1125 of hMSH2 was significant hypermethylated in resistant EOC patients (P =?1.06?×?10-14). In vitro analysis demonstrated that global demethylation increased cisplatin sensitivity along with a higher expression of the hMSH2 mRNA and protein. Knockdown hMSH2 reduced the cell sensitivity to cisplatin. MALDI-TOF mass spectrometry assay validated the strong association of hypermethylation of hMSH2 upstream region with platinum resistance. Spearman's correlation analysis revealed a significantly negative connection between methylation level of hMSH2 upstream region and its expression. The Kaplan-Meier analyses showed the high methylation of hMSH2 promoter region, and its low expressions are associated with worse survival. In multivariable models, hMSH2 low expression was an independent factor predicting poor outcome (P =?0.03, HR?=?1.91, 95%CI?=?1.85-2.31).ConclusionThe hypermethylation of hMSH2 upstream region is associated with platinum resistant in EOC, and low expression of hMSH2 may be an index for the poor prognosis.

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Epigenetic Regulation of the Homeobox Gene MSX1 Associates with Platinum-Resistant Disease in High-Grade Serous Epithelial Ovarian Cancer.

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