Abstract 5206: Systems biology identification of processes/pathways facilitating the development of high-grade serous ovarian cancer

Abstract

Abstract Previously, based on well-known stem cell phenotypes (sphere formation, potent tumorigenicity, embryonic gene expression, and chemoresistance), we used patient tumors to isolate high-grade serous (HGS) ovarian cancer-initiating cells (OCICs) that express the cell surface markers CD44 (a hyaluronate receptor) and CD117 (c-kit) (Zhang et al., 2008, Cancer Res 68:4311). Here, to identify biological pathways that underlie HGS ovarian tumorigenesis, including the specific role of OCICs in that process, we performed integrated analyses of global gene expression, DNA copy number, and DNA methylation patterns. To that end, OCICs and “bulk” (i.e., disaggregated but unsorted) tumor cells were compared to primary human normal ovarian surface epithelial (nOSE) cells that, along with fallopian tube epithelial (FTE) cells, represent hypothesized cells-of-origin for HGS pelvic cancers. Principle components analysis and unsupervised hierarchical clustering revealed distinct DNA methylation and gene expression profiles for replicate (n=3) samples of each cell type (i.e., OCIC, bulk tumor, and nOSE). Gene ontology and additional unsupervised analyses of “gene expression signatures” corresponding to the epithelial-to-mesenchymal transition (82 of 159 signature genes), TGF-beta (47 of 86 genes), and Wnt (75 of 151 genes) pathways demonstrated well-defined segregation of the three cell types, with mesenchymal and Wnt signaling hierarchies being nOSE > OCIC > bulk tumor cells. To examine early events in HGS ovarian tumorigenesis, previously published (Tone et al., 2008, Clin Cancer Res 14:4067) gene expression datasets were employed to show that nOSE, OCIC, and bulk ovarian tumor cell transcriptomes distinctly segregate from normal (FTE) and malignant fallopian epithelial transcriptomes. Interestingly, the largest divergence was between the nOSE and FTE gene expression profiles. Finally, DNA methylation and gene expression patterns were integrated, implicating specific networks/circuits in ovarian carcinogenesis. Taken together, these results support a mesenchymal-to-epithelial transition during ovarian tumorigenesis, reveal legitimate therapeutic targets (at the pathway level), and raise uncertainty that surface epithelial cells of the fallopian tube and ovary are reciprocal cells-of-origin for HGS pelvic carcinomas. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5206. doi:1538-7445.AM2012-5206