Abstract 2978: DNA methylation changes during epithelial-to-mesenchymal transition in ovarian cancer cells.

Abstract

Abstract Epithelial-to-mesenchymal transition (EMT) is a required step in the process of metastasis and has been linked to cancer cell stemness. We hypothesized that aside from defined genetic changes associated with EMT, epigenetic mechanisms are also involved. We determined DNA methylation changes in SKOV3 ovarian cancer (OC) cells undergoing TGFβ-induced EMT by using the Infinium HumanMethylation450 array. Methylation of sites was expressed as ß-values ranging from 0 (completely unmethylated) to 1 (completely methylated). Methylation of 468 and 390 sites changed significantly (P<.01, ANOVA and FDR<0.05) after 48h and 120h of TGFβ stimulation, of which 31 and 72 sites changed >1.25-fold. The majority of changes (∼66%) reflected TGFβ-induced demethylation. Methylation of 160 sites changed similarly at 48 and 120h indicating that approximately 40% of changes were sustained. PCA analysis demonstrated that the removal of TGFβ was associated with reversal of DNA methylation changes at most sites and restitution of the baseline methylome. Pathway analysis identified DNA methylated genes involved in functional networks relevant to EMT and cancer progression, including: 1) cell morphology and development (39 genes), 2) cell growth and proliferation, and cell death and survival (34 genes), 3) cellular assembly and organization (22 genes), 4) DNA replication, recombination and repair (17 genes), and 5) gene expression, cell signaling, and cellular movement (15 genes). Validation of the relevant genes is ongoing. Treatment of OC cells with the DNA methyl transferase inhibitor SGI-110 prevented TGFβ-induced EMT and reduced by two-fold the number of cells with stem cell characteristics (ALDH1+). These results demonstrate that DNA methylation is a dynamic process involved in regulation of genes implicated in EMT and metastasis. Citation Format: Horacio Cardenas, Chirayu Goswami, Kenneth P. Nephew, Daniela Matei. DNA methylation changes during epithelial-to-mesenchymal transition in ovarian cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2978. doi:10.1158/1538-7445.AM2013-2978