Abstract 2995: Autophagy as a key driver of waterpipe smoke-induced lung cancer cell plasticity and resistance
Authors: Zaarour Rania F. , Sharda Mohak , Azakir Bilal , Venkatesh Goutham Hassan , Khouzam Raefa Abou , Rifath Ayesha , Nizami Zohra , Abdullah Fatima , Mohammad Fatin , Nawafleh Husam , ElSayed Yehia , Chouaib Salem 
Published: June 2022

Smoking is the number one risk factor for lung cancer and tobacco smokers are at 20 to 40 times higher risk of developing lung cancer in comparison to non-smokers. We have previously shown that exposing lung cancer cell lines to tobacco smoke condensate generated from waterpipe (WP) interferes with cell proliferation, cell plasticity, DNA damage and tumor cell recognition and killing by natural killer (NK) cells. Global transcriptomic analysis identified an expression profile of genes that best distinguished treated and non-treated cells involving several pathways including those involved in epithelial to mesenchymal transition (EMT) and stemness. Because of the important role of autophagy in tumor resistance and progression, we investigated its relationship with WP smoking. We first showed an activation of autophagy as reflected by LC3 and P62 in lung cancer cell lines in response to WPS. Interestingly, our data revealed that WPS-induced EMT and cancer stemness involved autophagy induction. The autophagy response in smokers with lung adenocarcinoma as compared to non-smokers with lung adenocarcinoma was investigated using TCGA lung adenocarcinoma bulk RNA-seq dataset with the available patient metadata on smoking status. Preliminary results based on a machine learning classification model using Random Forest indicate that smokers have an increase in autophagy activating genes as compared to non-smokers. Comparative analysis of lung adenocarcinoma molecular signatures in affected patients with a long-term active exposure to smoke compared to patients who have not had any active exposure to smoke indicate a higher tumor mutational burden, CD8+ T-cell level and lower dysfunction level in smokers. Multivariate regression analyses confirm these results even after controlling for confounding factors like age, gender, and tumor stage. While the checkpoint genes tested PD1, PDL1, PDL2 and CTLA-4, had no difference between smokers and non-smokers, B7-1, B7-2, IDO1 and CD200R1 had higher expression in non-smokers than smokers. Because multiple factors in the tumor microenvironment dictate the success of immunotherapy, in addition to the expression of immune checkpoint genes, our analysis explains why patients who are smokers with lung adenocarcinoma respond better to immunotherapy, even though there are no relative differences in immune checkpoint genes in the two cohorts. Therefore, targeting autophagy in lung adenocarcinoma patients in combination with checkpoint inhibitors, targeted therapies or chemotherapy should be considered in smoker patients with lung adenocarcinoma.

Citation Format: Rania F. Zaarour, Mohak Sharda, Bilal Azakir, Goutham Hassan Venkatesh, Raefa Abou Khouzam, Ayesha Rifath, Zohra Nizami, Fatima Abdullah, Fatin Mohammad, Husam Nawafleh, Yehia ElSayed, Salem Chouaib. Autophagy as a key driver of waterpipe smoke-induced lung cancer cell plasticity and resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2995.