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The Diversity of Methylation Patterns in Serous Borderline Ovarian Tumors and Serous Ovarian Carcinomas

ABSTRACT: Background: Changes in DNA methylation patterns are a pivotal mechanism of carcinogenesis. In some tumors, aberrant methylation precedes genetic changes, while gene expression may be more frequently modified due to methylation alterations than by mutations. Methods: Herein, 128 serous ovarian tumors were analyzed, including borderline ovarian tumors (BOTS) with (BOT.V600E) and without (BOT) the BRAF V600E mutation, low-grade (lg), and high-grade (hg) ovarian cancers (OvCa). The methylome of the samples was profiled with Infinium MethylationEPIC microarrays. Results: The biggest number of differentially methylated (DM) CpGs and regions (DMRs) was found between lgOvCa and hgOvCa. By contrast, the BOT.V600E tumors had the lowest number of DM CpGs and DMRs compared to all other groups and, in relation to BOT, their genome was strongly downmethylated. Remarkably, the ten most significant DMRs, discriminating BOT from lgOvCa, encompassed the MHC region on chromosome 6. We also identified hundreds of DMRs, being of potential use as predictive biomarkers in BOTS and hgOvCa. DMRs with the best discriminative capabilities overlapped the following genes: BAIAP3, IL34, WNT10A, NEU1, SLC44A4, and HMOX1, TCN2, PES1, RP1-56J10.8, ABR, NCAM1, RP11-629G13.1, AC006372.4, NPTXR in BOTS and hgOvCa, respectively. Conclusions: The global genome-wide hypomethylation positively correlates with the increasing aggressiveness of ovarian tumors. We also assume that the immune system may play a pivotal role in the transition from BOTS to lgOvCa. Given that the BOT.V600E tumors had the lowest number of DM CpGs and DMRs compared to all other groups, when methylome is considered, such tumors might be placed in-between BOT and OvCa.

ORGANISM(S): Homo sapiens

PROVIDER: GSE267068 | GEO | 2024/10/18

REPOSITORIES: GEO

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Project description:Background. Genome-wide expression changes are associated with development of chemoresistance in patients with ovarian cancer (OVCA); the BCL2 antagonist of cell death (BAD) apoptosis pathway may play a role in clinical outcome. Methods. We analyzed specimens and/or genomic data from 1,406 patients and 116 cancer cell lines. Genome-wide expression changes and cisplatin-resistance were evaluated in OVCA cell lines subjected to a total of 144 (cisplatin)-treatment/recovery cycles. Pathway analysis was performed on genes associated with increasing cisplatin-resistance. BAD protein phosphorylation was studied in patient samples and cell lines, and small interfering RNAs (siRNA) used to explore the pathway as a therapeutic target. We evaluated the influence of BAD-pathway expression on chemosensitivity and/or clinical outcome using genomic data from 60 human cancer cell lines and ovarian, breast, colon, and brain cancers from 1,258 patients. Results. The BAD pathway was associated with evolution of OVCA cell line cisplatin-resistance (P<0.001) and resistance of 7 human cancer cell types to 8 cytotoxic agents (P<0.05). OVCA chemoresistance was associated with BAD protein phosphorylation, and targeted siRNA modulation produced corresponding changes in chemosensitivity. Expression of a 47-gene BAD-pathway signature was associated with survival of 1,258 patients with ovarian, breast, colon, and brain cancer. The OVCA BAD-pathway signature survival advantage was independent of surgical cytoreductive status. Conclusions. The BAD apoptosis pathway influences the sensitivity of human cancers to a variety of chemotherapies, likely via modulation of BAD-phosphorylation. The pathway has clinical relevance as a potential biomarker of therapeutic response, patient survival, and as a promising therapeutic target. Twenty-eight (28) advanced-stage serous epithelial ovarian cancers were resected at the time of primary surgery from patients who would receive platinum-based therapy. The tumors were arrayed on Affymetrix HG-U133A GeneChips. The samples were analyzed with respect to the BAD pathway for correlation to overall survival and cisplatin response.

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The Diversity of Methylation Patterns in Serous Borderline Ovarian Tumors and Serous Ovarian Carcinomas

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