Project description:Cisplatin and carboplatin are the primary first-line therapies for the treatment of ovarian cancer. However, resistance to these platinum-based drugs occurs in the large majority of initially responsive tumors, subsequently resulting in a poor long-term prognosis. To model the onset of drug resistance, and investigate the DNA methylation alterations associated with cisplatin resistance, we treated clonally derived, drug-sensitive A2780 epithelial ovarian cancer cells with increasing concentrations of cisplatin. After several cycles of drug selection, the isogenic drug-sensitive and -resistant pairs were subjected to global CGI methylation microarray analyses. We treated clonally derived, drug-sensitive A2780 epithelial ovarian cancer cells with increasing concentrations of cisplatin. After several cycles of drug selection, the isogenic drug-sensitive and -resistant pairs were subjected to global CGI methylation analyses by differential methylation hybridization (DMH) using a customed 44K promoter CGI microarray.
Project description:To determine the signaling networks that are dysregulated in platinum-resistant ovarian cancer, gene expression data were obtained from, and compared between, the ovarian cancer cell line, A2780, and its cisplatin-resistant derivative, A2780cis. Gene expression data from a cisplatin-sensitive ovarian cancer cell line (A2780) were collected and compared to gene expression data from a cisplatin-resistant cell line (A2780cis). 6 independent experiments were completed for both the sensitive and resistant cell lines.
Project description:We report the application of methyl-binding protein sequencing (MBD-seq) to global identify aberrant methylation between cisplatin sensitive and resistant ovarian cancer cell lines Detection of aberrant methylation states between cisplatin sensitive and resistant cell lines
Project description:Multiple DNA methylation changes have been associated with the acquisition of drug resistance; however it remains uncertain how many of these changes may represent critical DNA methylation drivers of chemoresistance. Using genome-wide DNA methylation profiling across 27,578 CpG sites on Illumina HumanMethylation27 bead array we identified loci at 4092 genes becoming hypermethylated in the chemoresistant A2780/cp70 ovarian tumour cell line compared to the parental sensitive A2780 line. Hypermethylation at CpG islands (CGI) is often associated with transcriptional silencing, however only 245 of these hypermethylated genes become down-regulated in A2780/cp70 as measured by microarray expression profiling. Treatment with the demethylating agent Decitabine induces re-sensitisation to cisplatin and resulted in re-expression of 41 of the down-regulated genes in cisplatin-resistant cells at the time point when re-sensitisation occurs. 13 of the 41 genes were consistently hypermethylated in two further independent cisplatin-resistant A2780 cell derivatives. Nine out of the 13 genes (ARHGDIB, ARMCX2, COL1A, FLNA, FLNC, MEST, MLH1, NTS, PSMB9) acquired methylation at CpG sites in ovarian tumours at relapse following chemotherapy or chemoresistant cell lines derived at the time of patient relapse. Furthermore, 5/13 candidate genes acquired methylation in drug-resistant in vivo-derived ovarian cancer sustaining (side population) cells. Therefore, this small set of genes are potential key drivers of chemoresistance and should be further evaluated as predictive biomarkers, both to existing chemotherapies, but also to epigenetic therapies used to modulate drug resistance. Array-based methylation profiling was performed using the Infinium HumanMethylation27 BeadChip in two cisplatin sensitive cell lines and three cisplatin resistant cell lines derived in vitro, four pairs of cisplatin sensitive and resistant cell lines derived in vivo, 7 pairs of tumour tissues obtained from patients before chemotherapy and at disease relapse, 2 pairs of IGROV1 SP and NSP cells. The reproducibility of the Infinium HumanMethylation27 BeadChips was evaluated using biological and technical replicates of matched chemosensitive/chemoresistant ovarian cancer cell lines PEO1/PEO4. Differential methylation cutoff was estimated from two biological replicates by bootstrap resampling.
Project description:Cisplatin and carboplatin are the primary first-line therapies for the treatment of ovarian cancer. However, resistance to these platinum-based drugs occurs in the large majority of initially responsive tumors, subsequently resulting in a poor long-term prognosis. To model the onset of drug resistance, and investigate the DNA methylation alterations associated with cisplatin resistance, we treated clonally derived, drug-sensitive A2780 epithelial ovarian cancer cells with increasing concentrations of cisplatin. After several cycles of drug selection, the isogenic drug-sensitive and -resistant pairs were subjected to global CGI methylation microarray analyses.
Project description:Cisplatin-resistance is a major cause of treatment failure in human ovarian cancer. Besides lots of genes involved, emerging evidences demonstrate that miRNAs contribute to cisplatin-resistance in cancer. We measured the miRNA expression profiles of cisplatin-resistant C13K ovarian cancer cell line compared with its cisplatin-sensitive OV2008 parent cell line using miRNA microarrays.
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.
Project description:We report the application of methyl-binding protein sequencing (MBD-seq) to global identify aberrant methylation between cisplatin sensitive and resistant ovarian cancer cell lines
Project description:The development of drug resistance is still a major impediment for the successful treatment of cancer, such as advanced stage ovarian cancer, which has a 5-year survival rate of only 30%. The molecular processes that contribute to resistance have been extensively studied, however, not much is known about the role of microRNAs. We compared microRNA expression profiles of three isogenic cisplatin sensitive and resistant cell line pairs. The only microRNA that was consistently downregulated (FDR = 0.000) in all resistant cell lines was miR-634. We investigated the effects of miR-634 modulation in ovarian cancer cell lines and patient derived tumor cells. Overexpression of miR-634 gave rise to a modest G1 phase block and enhanced apoptosis. Furthermore, miR-634 resensitized resistant ovarian cancer cell lines and patient derived tumor cells to cisplatin chemotherapy. Similarly, miR-634 enhanced the response of tumor cells to carboplatin and doxorubicin, but not to paclitaxel. We showed that miR-634 regulates cyclin D1 (CCND1), which is required for the G1-S phase transition, explaining the effects on the cell cycle. In addition, miR-634 repressed expression of GRB2, ERK2, RSK1 and RSK2, components of the Ras-MAPK pathway. Altogether, our findings suggest that miR-634 modulates several cancer relevant targets and therefore miR-634 is an attractive therapeutic candidate to resensitize chemotherapy resistant ovarian tumors. The miRNA expression profile was determined of three cisplatin sensitive/resistant cell line pairs (ovarian cancer cell line pair A2780/A2780 DDP; colon cancer cell line pair HCT8/HCT8 DDP; bladder cancer cell line pairT24/T24 DDP10).