Effects of cigarette smoke extracts on apoptosis and oxidative stress in two models of ovarian cancer in vitro

Cigarette smoke contains thousands of harmful components, many of which exert toxic effects on reproductive organs, including the ovaries, and their development. In this study, we investigated the effects of cigarette smoke extract (CSE) on cell proliferation, apoptosis and oxidative stress in the SKOV3 and OVCAR3 ovarian cancer cell lines. A water soluble tetrazolium (WST) assay revealed that the cell proliferation of both ovarian cells was significantly inhibited by three types of CSE in a concentration-dependent manner. Western blot analysis showed that the inhibition of cell proliferation was related to regulation of cell cycle-related protein expression. To determine the effects of cigarette smoke on the death of ovarian cells, we conducted a TUNEL assay, which revealed a time-dependent increase in TUNEL-stained cells in response to CSE exposure. Moreover, the protein expression of the Bcl-2 family signaling pathway observed upon Western blot analysis were consistent with the results of the TUNEL assay. We also examined the reactive oxygen species (ROS) generation in two ovarian cell lines using DCF-DA (5(6)-Carboxy-2′,7′-dichlorofluorescein diacetate) assay and ROS-Glo™ H2O2 assay to investigate the oxidative stress caused by CSE. Both ROS detection assays demonstrated an increase in the amount of ROS by CSE in ovarian cells, which was consistent with the results observed for the Keap1-Nrf2 pathway upon Western blot analysis. Taken together, these results suggest that CSE may induce cell proliferation inhibition and oxidative stress in ovarian cells.