Abstract 2350: xCT overexpression induces metabolic reprogramming, epigenetic alterations, and DNA damage in precancerous airway epithelial cells
Authors: Hill Dalton , Rahman Jamshedur , Kluwe Christien , Young Jamey , Hodges Emily , Massion Pierre P. 
Published: July 2021

Metabolic reprogramming and genomic instability are two hallmarks of cancer known to drive tumorigenesis. While each has been investigated individually, there is a growing interest in their interplay during early cancer development. High expression of the cystine/glutamate antiporter SLC7A11 (xCT) is frequently observed in lung cancer. Our laboratory previously demonstrated that overexpressing xCT in normal bronchial airway epithelial cells induced metabolic reprogramming and caused cells to display precancerous properties, such as increased proliferation and colony formation in soft agar. In this study, we further investigated the effects of xCT overexpression in the airway epithelium with the goal of elucidating the role of xCT in influencing cancer-driving hallmarks and the interplay of these hallmarks during early tumorigenesis. We hypothesized that xCT overexpression-induced metabolic reprogramming leads to epigenetic changes through the perturbation of epigenetic-related metabolite levels. Furthermore, we posited that this altered epigenome changes the expression levels of key genes involved in genome stability maintenance, ultimately inducing genomic instability. Utilizing a LC-MS/MS-based metabolomic analysis, we observed significantly altered levels of 224 different metabolites in our xCT overexpressing cells, including metabolites involved in epigenetic processes such as S-adenosylhomocysteine and acetyl-CoA. We found that xCT overexpression alters several global histone modifications, increasing H3K9me3 and H3K9ac by 3.2 (P = 0.02) and 3.9-fold (P = 0.02) respectively. We also showed that xCT overexpression increased global DNA methylation by 56% (P = 0.04). Additionally, RNA-seq revealed significant alterations (logFC&gt;2 or &lt;0.5, pAdj&lt;0.05) in the expression of over 100 genes, including a significant decrease in the expression of certain tumor suppressor genes such as TRIM29, and a significant increase in the expression of certain proto-oncogenes, such as CCND1. Finally, we discovered that xCT overexpression induces DNA damage, increasing the percentage of damaged DNA in comet tails in a comet assay by 15.1% (P = 0.002). Taken together, xCT overexpression in normal bronchial airway epithelial cells induces metabolic reprogramming, alters the epigenetic landscape and gene expression, and causes higher levels of DNA damage. Future experiments elucidating causal links between these processes, including ChIP-seq and WGBS are underway. This study provides a promising foundation for the connections between xCT-induced metabolic reprogramming, epigenetic alterations, and genomic instability, an imperative step in elucidating an effective, potentially multifaceted approach to preventing lung cancer development.

Citation Format: Dalton Hill, Jamshedur Rahman, Christien Kluwe, Jamey Young, Emily Hodges, Pierre P. Massion. xCT overexpression induces metabolic reprogramming, epigenetic alterations, and DNA damage in precancerous airway epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2350.