Abstract LB-048: c-Kit enhances ovarian cancer stemness via upregulating phospho-PHB in the lipid raft domain of the plasma membrane

Abstract

Phosphorylation of prohibitin (PHB) at threonine 258 (phospho-PHBT258) and tyrosine 259 (phospho-PHBY259) in human cancer-cell membranes is associated with an increase in the invasiveness and metastasis of cancer cells. Phospho-PHBY259 can regulate phospho-PHBT258 but not vice versa. Here, we found that stably overexpressing c-Kit in SKOV3 ovarian cancer cells (SKOV3_c-Kit) increased phospho-PHBY259, phospho-PHBT258 and PHB levels in the lipid raft domain of the plasma membrane. On the other hand, inhibition of c-Kit expression decreased PHB expression in SKOV3_c-Kit and Kuramochi ovarian cancer cells. Immunoprecipitation analysis showed that c-Kit interacts with PHB. SKOV3_c-Kit cells or SKOV3 cells overexpressing PHB in the lipid raft had higher levels of Notch3, NICD3 (Notch3 intracellular domain) and ABCG2 protein expression as compared to wild-type SKOV3 cells. Moreover, generation of SKOV3-G4 cells through serial passage of SKOV3 cells into nude mice ovary 4 times, revealed that the levels of c-Kit, Notch3, NICD3, phospho-PHBY259, phospho-PHBT258 and PHB in the lipid raft domain of SKOV3-G4 were significantly higher than wild-type SKOV3 cells. The SKOV3-G4 cells formed spheroids with stem cell-like properties such as higher expression of stem cell markers (Oct4, Nanog, SOX2). In addition, SKOV3-G4 cells exhibited more clonogenic potential and migration/invasion ability than wild-type SKOV3. These results suggest that c-Kit interacts with PHB in the lipid raft domain to phosphorylate PHB to increase invasiveness and stemness in ovarian cancer. Citation Format: Shu-Mei Y. Liang, Chia-Hsun Fang, Pu-Yuan Chang, Chi-Ming Liang. c-Kit enhances ovarian cancer stemness via upregulating phospho-PHB in the lipid raft domain of the plasma membrane [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 LB-048.