Ruo-Ran Mi1, Hong Ni. 1. Department of Gynecology and Obstetrics, General Hospital of TianJin Medical University, Tianjin, China.
Abstract
OBJECTIVES: The purpose of this study was to determine whether overexpression of MDM2 could sensitize the ovarian cancer cell line A2780. METHODS: The wild-type p53-expressing cell line A2780 was stably transfected with pCMV-MDM2 (A2780-MDM2) or pCMV (A2780-V) as control. MTT assay and clonogenic survival assay were used to measure the cisplatin sensitivity. FACS and host cell (CAT) reactivation assay were used to estimate the change of cell cycle and ability of repairing cisplatin-induced DNA damage. RESULTS: Parental A2780 and A2780-V had similar cisplatin sensitivities, whereas A2780-MDM2 was two- to threefold more sensitive to cisplatin. Repair of cisplatin-induced DNA damage was reduced in A2780 cells overexpressing MDM2, compared to A2780 cells in which wild-type p53 function was intact. After cisplatin treatment, A2780-MDM2 cells showed a pronounced S-phase arrest; however, A2780 cells with intact wild-type p53 arrested primarily in G2/M phase. CONCLUSIONS: MDM2 overexpression can increase cisplatin cytotoxicity in A2780, with loss of G1/S checkpoint control and decreased cisplatin-DNA adduct repair. This suggests that ovarian cancers that overexpress MDM2 may be amenable to treatment with platinum compounds.
OBJECTIVES: The purpose of this study was to determine whether overexpression of MDM2 could sensitize the ovarian cancer cell line A2780. METHODS: The wild-type p53-expressing cell line A2780 was stably transfected with pCMV-MDM2 (A2780-MDM2) or pCMV (A2780-V) as control. MTT assay and clonogenic survival assay were used to measure the cisplatin sensitivity. FACS and host cell (CAT) reactivation assay were used to estimate the change of cell cycle and ability of repairing cisplatin-induced DNA damage. RESULTS: Parental A2780 and A2780-V had similar cisplatin sensitivities, whereas A2780-MDM2 was two- to threefold more sensitive to cisplatin. Repair of cisplatin-induced DNA damage was reduced in A2780 cells overexpressing MDM2, compared to A2780 cells in which wild-type p53 function was intact. After cisplatin treatment, A2780-MDM2 cells showed a pronounced S-phase arrest; however, A2780 cells with intact wild-type p53 arrested primarily in G2/M phase. CONCLUSIONS:MDM2 overexpression can increase cisplatincytotoxicity in A2780, with loss of G1/S checkpoint control and decreased cisplatin-DNA adduct repair. This suggests that ovarian cancers that overexpress MDM2 may be amenable to treatment with platinum compounds.