A novel human endometrial epithelial cell line for modeling gynecological diseases and for drug screening.

Endometrium-related malignancies including uterine endometrioid carcinoma, ovarian clear cell carcinoma and ovarian endometrioid carcinoma are major types of gynecologic cancer, claiming more than 13,000 women's lives annually in the United States. In vitro cell models that recapitulate "normal" endometrial epithelial cells and their malignant counterparts are critically needed to facilitate the studies of pathogenesis in endometrium-related carcinomas. To achieve this objective, we have established a human endometrial epithelial cell line, hEM3, through immortalization and clonal selection from a primary human endometrium culture. hEM3 exhibits stable growth in vitro without senescence. hEM3 expresses protein markers characteristic of the endometrial epithelium, and they include PAX8, EpCAM, cytokeratin 7/8, and ER. hEM3 does not harbor pathogenic germline mutations in genes involving DNA mismatch repair (MMR) or homologous repair (HR) pathways. Despite its unlimited capacity of in vitro proliferation, hEM3 cells are not transformed, as they are not tumorigenic in immunocompromised mice. The cell line is amenable for gene editing, and we have established several gene-specific knockout clones targeting ARID1A, a tumor suppressor gene involved in the SWI/SNF chromatin remodeling. Drug screening demonstrates that both HDAC inhibitor and PARP inhibitor are effective in targeting cells with ARID1A deletion. Together, our data support the potential of hEM3 as a cell line model for studying the pathobiology of endometrium-related diseases and for developing effective precision therapies.

Inhibition of the MYC-Regulated Glutaminase Metabolic Axis Is an Effective Synthetic Lethal Approach for Treating Chemoresistant Ovarian Cancers.

Amplification and overexpression of the MYC oncogene in tumor cells, including ovarian cancer cells, correlates with poor responses to chemotherapy. As MYC is not directly targetable, we have analyzed molecular pathways downstream of MYC to identify potential therapeutic targets. Here we report that ovarian cancer cells overexpressing glutaminase (GLS), a target of MYC and a key enzyme in glutaminolysis, are intrinsically resistant to platinum-based chemotherapy and are enriched with intracellular antioxidant glutathione. Deprivation of glutamine by glutamine-withdrawal, GLS knockdown, or exposure to the GLS inhibitor CB-839 resulted in robust induction of reactive oxygen species in high GLS-expressing but not in low GLS-expressing ovarian cancer cells. Treatment with CB-839 rendered GLShigh cells vulnerable to the poly(ADP-ribose) polymerase (PARP) inhibitor, olaparib, and prolonged survival in tumor-bearing mice. These findings suggest consideration of applying a combined therapy of GLS inhibitor and PARP inhibitor to treat chemoresistant ovarian cancers, especially those with high GLS expression. SIGNIFICANCE: Targeting glutaminase disturbs redox homeostasis and nucleotide synthesis and causes replication stress in cancer cells, representing an exploitable vulnerability for the development of effective therapeutics. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/20/4514/F1.large.jpg.