High grade serous ovarian cancer, the most lethal subtype of ovarian cancer, can originate in either the fallopian tube epithelium (FTE) or ovarian surface epithelium (OSE). PAX8 is a lineage specific transcription factor that is ubiquitously expressed in HGSOC. We have shown that knockdown of PAX8 using shRNA in multiple ovarian tumor cells lines leads to apoptosis, suggesting that PAX8 plays an essential role in cancer survival. In this study, we used CRISPR technology to delete PAX8 from the OVCAR8 cell line. PAX8 deletion led to a decrease in migration and invasion in vitro and an increase in survival and a reduction in tumor volume in vivo. Previous work using RNA-sequencing and ChIP-sequencing identified cell adhesion as a top differentially expressed gene between malignant ovarian cancer and benign fallopian tube cell lines. We performed quantitative proteomic analysis of the OVCAR8-PAX8-/- cell line to define PAX8 altered proteins. We also performed quantitative proteomics and transcriptomic analyses on a previously generated murine OSE cell line with forced PAX8 expression (MOSE-PAX8). These analyses identified several genes that contribute to an increase in migration and EMT. Specifically, our data indicates PAX8 upregulates key drivers involved in altering cell morphology including the GTPases: RhoA, Cdc42, and Ras. Inhibition of RhoA led to a greater decrease in migration for both OVCAR8-PAX8-/- and MOSE-PAX8 when compared to control. Inhibition of Ras had a greater effect in OVCAR8-PAX8-/- while inhibition of Cdc42 had a greater effect in MOSE-PAX8. These data provide a mechanistic explanation for the role of PAX8 on increasing migration and metastasis in ovarian cancer.

Citation Format: Laura Hardy, Melissa Pergande, Angel Hernandez, Stephanie Cologna, Joanna Burdette. PAX8 increases migration and metastasis of high grade serous ovarian cancer through upregulation of Rho GTPases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4039.