Abstract A12: Regulation of ovarian cancer OVCAR-3 cell proliferation and viability by calcium/calmodulin-dependent protein kinase kinase 2

Abstract

Abstract Protein kinases play crucial roles in cancer progression and are considered potential targets for novel anti-cancer therapeutics. Oncogenic kinases mediate a variety of events characteristic of the malignant phenotype including transcriptional activation, accelerated cell proliferation and enhanced cellular survival. Ca2+/Calmodulin-dependent Protein Kinase Kinase 2 (CaMKK2) has been implicated as a signaling mechanism in prostate and breast cancers, but has not been studied in ovarian cancer (OvCa). We report here the following. CaMKK2 expression is greatly increased in high grade serous papillary cystadenocarcinoma compared to benign tissue. Knockdown of CaMKK2 expression by RNA interference in OvCa OVCAR-3 cells resulted in slowing of cell growth and decreased number of cells entering S phase. At the molecular level, CaMKK2 knockdown led to significant decreases in cyclin D1 expression at both mRNA and protein levels and to a drop in phosphorylation of the retinoblastoma tumor suppressor (Rb) at Ser 807/811. These results indicate that CaMKK2 expression in OVCAR-3 OvCa cells is required for optimal G1/S phase cell cycle progression and proliferation. CaMKK2 knockdown also resulted in a significant decrease in OVCAR-3 cell survival and an increase in both Poly ADP Ribose Polymerase (PARP) cleavage (inactivation) and in the activity of executioner Caspases-3/7 indicating that CaMKK2 knockdown in OVCAR-3 cells results in apoptosis. Preliminary data showed a decrease in phosphorylation of the activation site of Akt (Thr 308) in CaMKK2 depleted cells suggesting that the G1/S phase cell cycle arrest and apoptosis in CaMKK2 silenced cells may occur either directly or indirectly through an Akt-dependent pathway. Altogether these data show that CaMKK2 is required for optimal growth and viability of OVCAR-3 cells and furthermore imply that CaMKK2 may be a promising and novel therapeutic target for OvCa. Citation Format: Angela M. Gocher, Gissou Azabdaftari, Arthur M. Edelman. Regulation of ovarian cancer OVCAR-3 cell proliferation and viability by calcium/calmodulin-dependent protein kinase kinase 2. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A12.