Abstract 384: Secondhand smoke exposure alters cisplatin-induced cell death and alters cell death and survival pathway in HNSCC
Authors: Sadhasivam Balaji , Manyanga Jimmy , Ganapathy Vengatesh , Bouharati Célia , Rubenstein David , Wren Jonathan , Acharya Pawan , Zhao Daniel , Queimado Lurdes 
Published: April 2023

BACKGROUND: Secondhand smoke (SHS) contains more than 7000 chemicals, 70of which are carcinogens and it is estimated that every one in four Americans areinvoluntarily exposed to SHS. Carcinogenesis induced by SHS exposure isunclear, though SHS exposure is associated with various cancers including headand neck squamous cell carcinoma (HNSCC). Recently, it has been shown thatSHS exposure is a significant independent predictor of HNSCC recurrence. Wehave shown that in vitro exposure to SHS increases HNSCC cisplatin resistance.

AIMS: Our study examines the effect of SHS smoke exposure on cisplatin-induced HNSCC cancer cell death and the possible mechanisms behind thisobservation.

METHODS: Sidestream smoke (SS), the main component of SHS,was extracted as previously described. Authenticated HNSCC cell lines (UM-SCC1 & WSU-HN6) were exposed to SS extract for 48 hours at doses mimickingthe nicotine levels observed in the saliva of passive smokers. Then, cancer cellswere treated with cisplatin in the presence or absence of SS extract. Cisplatin-induced cancer cell death was measured using Incucyte® S3 Live-Cell imaginganalysis. Transcriptomic analysis following RNA-sequencing was performedusing Ingenuity Pathway Analysis. Data were subjected to ANOVA.

RESULTS: Our live-cell imaging system revealed that HNSCC cells exposed to SS extractsignificantly decreased cisplatin-induced cancer cell death at various time points

compared with cells treated with cisplatin alone in both cell lines. The HNSCCcells treated only with SS extract did not show any change in cell death at 0, 12,24, 48, 72, and 96 hours. RNA-sequencing data revealed that cell death andsurvival pathways are the most changed pathways in the SS extract-treatedgroup compared with unexposed HNSCC cells.

CONCLUSIONS: Our studydocuments for the first time that even short-term exposure to SHS allows cells toevade cisplatin-induced cell death and can lead to head and neck cancercisplatin resistance. At the molecular level, SHS exposure alters genes that areassociated with cell death and survival. Further, HNSCC patients-basedobservations and mechanistic studies are warranted.

FUNDING: This work was partially supported by the National Cancer Institute of the NationalInstitutes of Health (R33CA202898, R01CA242168, and P30CA225520), theTSET Health Promotion Cancer Center, and the Oklahoma Center forAdvancement of Science and Technology (HR16-007). Dr. Queimado holds aPresbyterian Health Foundation Endowed Chair in Otorhinolaryngology Position.

Citation Format: Balaji Sadhasivam, Jimmy Manyanga, Vengatesh Ganapathy, Célia Bouharati, David Rubenstein, Jonathan Wren, Pawan Acharya, Daniel Zhao, Lurdes Queimado. Secondhand smoke exposure alters cisplatin-induced cell death and alters cell death and survival pathway in HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 384.