Endometrial cancer (EC) is the most common gynecologic malignancy, with approximately 20% of EC patients developing advanced stage recurrent tumors and frequent metastasis. Our goal was to investigate whether DNA methylation signatures associated with low promoter methylation (hypomethylation) and specific oncogenic signaling delineate predictive markers of endometrial cancer recurrence. Global screening by Methyl-CpG-capture sequencing revealed aberrant DNA methylation in our endometrial cancer cohort and identified a subset of bone morphogenetic protein family (BMP1, 2, 3, 4, and 7) exhibiting frequent hypomethylation in primary tumors with subsequent recurrence compared with non-recurrent tumors. This epigenetic signature correlated with poor survival and was validated in The Cancer Genome Atlas endometrial cancer cohort. Our functional studies also implicated epidermal growth factor receptor (EGFR) pathway in the transcriptional activation of these BMPs and inducing epithelial-mesenchymal transition (EMT). In addition to AKT and MAPK, the epithelial cell adhesion molecule (EpCAM) mediated these actions by EGFR. EpCAM involvement in cancer progression includes nuclear co-translocation of its intracellular domain EpICD with Lef-1 complexes and targeting oncogene promoter activation. In this study, EGF stimulated EpICD-Lef-1 binding on BMP genes accompanied with histone active modification marks. EpICD knockdown resulted in increased repressive histone marks and DNA methylation at these loci, suggesting that EpICD occupancy is involved in their epigenetic modification to an open transcriptional conformation. Knockdown of candidate BMPs led to decreased endometrial cancer cell invasiveness, implicating them in aggressive growth. Extending our studies, we performed ChIP-Seq analysis to identify global regulation by the EpICD-Lef-1 complexes in endometrial cancer. Interestingly, under basal levels only about 28% of loci targeted by either EpICD or Lef-1 were commonly targeted by EpICD-Lef-1, with common targets increasing to about 50% in 24 hrs and 73% in 48 hrs post EGF treatment. This indicates that EGFR signaling stimulates a time-course dependent enrichment of EpICD-Lef-1 convergence on target loci. Our initial studies of these EpICD target pathways included genes with cell adhesion functions. Future studies on the regulation of the EpICD-Lef-1 regulated genes and their mechanisms of action in aggressive endometrial cancer will provide a better understanding of this gene network in endometrial cancer. Hypomethylation signatures of candidate loci in this regulatory network may present putative predictive markers of poor survival and which may be used to tailor individualized therapy.

Citation Format: Ya-Ting Hsu, Fei Gu, Yi-Wen Huang, Joseph Liu, Jianhua Ruan, Rui-Lan Huang, Chiou-Miin Wang, Chun-Liang Chen, Rohit R. Jadhav, Yao Wang, Victor X. Jin, Hung-Cheng Lai, David G. Mutch, Paul J. Goodfellow, Ian M. Thompson, Nameer B. Kirma, Tim H.M. Huang. EpCAM-mediated hypomethylation of BMP and cell adhesion genes is associated with advanced endometrial cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1376. doi:10.1158/1538-7445.AM2014-1376

©2014 American Association for Cancer Research.
2014