Abstract: Objective To test the status of Keap-1/Nrf-2 pathway in cisplatin-resistant Skov3/DDP cells, and the contribution of these molecular in cisplatin (cis-pt) resistance. Methods Skov3/DDP was divided into four groups：blank, cis-pt, Keap-1 up-regulated and Keap-1 plus cis-pt. Keap-1 was up-regulated in Skov3/DDP cells by trans-faction with pFlag-CMV-Keap-1 plasmid which was validated by expression of flag and increase of Keap-1 level using Western blot. The effect of Keap-1 up-regulation on Nrf-2 re-distribution was analyzed by Western blot. FCM was employed to detect apoptosis. ROS level was measured by DHE staining. Results The expression of Keap-1 was decreased obviously in Skov3/DDP cells compared with Skov3 cells (P<0.05), Nrf-2 in Skov3/DDP cells detected mainly in nucleus. Then, the Keap-1 was successfully up-regulated (3.5 fold) by exogenous expression of pFlag-CMV-Keap-1 plasmid, as a result, nucleus portion of Nrf-2 was significantly reduced (0.2 fold). Next, the FCM results showed significant increase of apoptosis in Keap-1 up-regulated Skov3/DDP cells after cis-pt administration (P<0.05). Finally, ROS level was raised significantly in Skov3/DDP cells treated with cis-pt plus Keap-1 up-regulation. Conclusions Up-regulation of Keap-1 reduced the nucleus portion of Nrf-2 and reverses cisplatin resistance in Skov3/DDP cells.

Key words: ovarian cancer, cis-pt resistance, Keap-1, Nrf-2, ROS