Unknown,Transcriptomics,Genomics,Proteomics

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Expression data identifying hypermethylated genes associated with acquired cisplatin resistance

ABSTRACT: Treatment-related DNA hypermethylation may play a role in creating drug resistant phenotypes by inactivating genes that are required for cytotoxicity, but there have been no genome-wide studies to systematically investigate methylation of individual genes following exposure to chemotherapy. We used microarrays and a pharmacologic unmasking protocol in isogenic cisplatin-sensitive and -resistant cell lines to identify genes that were down-regulated in cisplatin-resistant cells and could be re-activated by the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza-dC). We identified several hundred genes that were down-regulated in each resistant cell line. Of these, 30 genes were common to > 2 cell lines, and/or reported to be down-regulated in previous studies. siRNA knockdown of two candidate genes increased cell viability with cisplatin treatment in sensitive parental cell lines Cisplatin-sensitive and -resistant SCC cells and KB and KB cisplatin-resistant clones (n=2) were split to low density and treated with freshly prepared 5 microM 5-Aza-dC dissolved in 50% acetic acid/50% PBS or were mock treated with the same volume of vehicle in the media for 5 days. Subsequently, RNA was extracted and hybridized on Affymetrix U133A microarrays. Signal intensity and statistical significance was established for each transcript, and a 2-fold decrease in signal in each paired sensitive/resistant cell line in combination with 1.5-fold increase after 5Aza-dC treatment was used to identify candidate genes.

ORGANISM(S): Homo sapiens

SUBMITTER: Constance Monitto

PROVIDER: E-GEOD-19397 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Identification of hypermethylated genes associated with cisplatin resistance in human cancers.

Chang Xiaofei X Monitto Constance L CL Demokan Semra S Kim Myoung Sook MS Chang Steven S SS Zhong Xiaoli X Califano Joseph A JA Sidransky David D

Cancer research 20100309 7

Cisplatin is among the most widely used cytotoxic anticancer agents in solid tumors; however, the development of secondary resistance remains a major obstacle to clinical efficacy. Treatment-related DNA hypermethylation may play a role in creating drug-resistant phenotypes by inactivating genes that are required for cytotoxicity. We applied a pharmacologic unmasking approach to detect hypermethylated genes whose inactivation contributes to cisplatin resistance. Using three pairs of isogeneic, ci ...[more]

PMID: 20215521

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Project description:Understanding the mechanism of resistance in platinum-based regimens for the treatment of high-grade serous ovarian cancer (HGSOC) is important for identifying new therapeutic targets to improve the clinical outcome of ovarian cancer patients. Mass spectrometry-based proteomic strategy was applied to spheroidal cisplatin sensitive and resistant HGSOC generated cell lines in the absence and presence of cisplatin drug. A complete expressed HGSOC proteome and phosphoproteome was characterized in cisplatin sensitive and resistant HGSOC cell lines providing insight into the mechanism of resistance development. PCA analysis showed that phosphorylation of a few proteins provides better classification than the whole proteome of the cellular subtypes. Specifically, a distinctive phosphoproteomic signature between cisplatin sensitive and resistant cell lines in the absence of drug was observed. This same phosphoproteomic signature was observed in our cisplatin sensitive cell line in the absence and presence of drug, indicating a vital role for phosphorylation of proteins in resistance development to cisplatin. The most phosphorylated protein was sequestosome (p62/SQSTM1). Differential expressions of apoptosis by the prognostic factor ratio of Bcl-2/Bax and autophagy, known to be regulated by p62/SQSTM1, was validated in the proteome data and by western blot analysis. A significant increase in apoptosis in the presence of cisplatin was observed in only the sensitive cell line while autophagy revealed increased expression in the resistant relative to sensitive cell line. Furthermore, site specific phosphorylation on 20 modified residues of sequestosome was characterized. Elevated expression of phosphorylation of sequestosome in resistant HGSOC cell lines was validated with western blot analysis. Here, we propose phosphorylation of sequestosome to be a marker and key in cisplatin resistance development in HGOSC ovarian cancers by shuttling ubiquitinated proteins to the autophagy pathway and influencing down-regulation of apoptosis.

Dataset Information

Expression data identifying hypermethylated genes associated with acquired cisplatin resistance

Publications

Identification of hypermethylated genes associated with cisplatin resistance in human cancers.

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