Abstract 80: Electronic cigarette aerosols increase clonogenic survival in oral cancer cells after cisplatin treatment

Abstract

Abstract Background and Aim: Are electronic cigarettes (ECs) safer than combustible tobacco? No one knows the answer yet. ECs are devices that deliver an aerosol from a heated mixture of propylene glycol, vegetable glycerin, and flavors, with or without nicotine. Short-term EC studies are mostly limited and inconclusive. Despite unknown long-term health effects, the use of ECs has increased alarmingly over the past decade. EC aerosols contain unique chemicals as well as other chemicals similar to those found in tobacco smoke. Tobacco smoking during cancer treatment has been associated with increased drug resistance and reduced overall survival rate. The awareness of the dangers of cigarette smoking and the paucity of studies evaluating the safety of ECs pose a dilemma for cancer patients who might be considering switching to ECs during chemotherapy. Here, we sought to examine the effects of EC aerosol extracts exposure on cell survival in oral cancer cells during cisplatin treatment. Methods: EC aerosol extracts were collected from two brands of ECs as previously described. Mainstream tobacco smoke (MS) extract was used as a positive control. To evaluate clonogenic survival after cisplatin treatment, oral cancer cells were exposed for 48 h to EC aerosol extracts at nicotine doses comparable to those observed in EC users. Next, cells were treated with both EC aerosol extracts and cisplatin (or vehicle-control) for another 48 h. After treatment, cells were counted and seeded in 6-well plates and colony formation was assessed two weeks later. Colonies were fixed with methanol followed by staining with 0.5% crystal violet in 25% methanol and counted manually. Only colonies with at least 50 cells were counted. Data were analyzed by Student's t-tests and one-way analysis of variance (ANOVA). Results: After cisplatin treatment, cells exposed to EC aerosol extracts showed a significant increase in clonogenic survival fraction compared to vehicle-control treated cells. Furthermore, cells exposed to EC aerosol extracts formed visibly larger colonies. An increase in clonogenic survival was also observed in MS extract-treated cells. Conclusions: Collectively, our data suggest that short-term exposure to EC aerosol can induce cisplatin resistance in oral cancer cells, thus allowing the cells to survive and form colonies. These findings are particularly important in paving the way to understanding whether ECs are a safer alternative for oral cancer patients undergoing chemotherapy. Citation Format: Jimmy Manyanga, Toral R. Mehta, Lurdes Queimado. Electronic cigarette aerosols increase clonogenic survival in oral cancer cells after cisplatin treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 80.