Abstract 1992: Serine hydroxymethyltransferase-2 as regulator of oxidative stress and chemoradiation resistance in lung adenocarcinoma

Abstract Purpose/Objective(s): Lung cancer is the leading cause of cancer deaths in the United States and worldwide. There has been little improvement in survival over the past several decades and surgery is generally considered to be the only curative treatment. We, therefore, performed a genome-wide functional genomics screen on human lung adenocarcinoma cells to identify genes involved in chemo- and radiotherapy resistance. Based on these results, we hypothesized that serine hydroxymethyltransferase-2 (SHMT2), which catalyzes the conversion of serine to glycine, is a target for chemoradiotherapy resistance in preclinical models of lung adenocarcinoma. Materials/Methods: PC9 cells were treated three times with 1 uM cisplatin and 2 Gy radiation before being subjected to genomic, untargeted metabolomic, or proteomic analysis. For the genomic analysis, PC9 cells were transfected with an shRNA viral library containing ~60,000 individual shRNAs following treatment. shRNAs that were depleted were hypothesized to represent genes involved in chemo-/radioresistance. Proteomics analysis was conducted after treatment and quantified by tandem mass tags isobaric labeling, totaling ~2,100 quantifiable proteins. An untargeted metabolomics approach was conducted after treatment, using gas chromatography mass spectrometry to quantify ~95 metabolites. Protein expression following treatment was determined by Western blot. Potential drug targets were assessed via colony formation assays. The Cancer Genome Atlas (TCGA) was queried to confirm in vivo human clinical correlations. Results: Our genomic, proteomic, and metabolomics screens indicated glutathione detoxification and oxidative stress response were major compensatory pathways upregulated after cisplatin and radiation treatment. We validated three targets, SLC7A11, GPX4, and SHMT2, as genes involved in chemo-radioresistance in vitro. The respective small molecule inhibitors of these gene targets, IKE, RSL3, and SHIN1, were synergistic when combined with cisplatin and radiation. SHIN1 appeared to also induce oxidative stress through ferroptosis, although this mechanism of cell death must be interrogated further. Analysis of TCGA revealed SHMT2 expression is upregulated in human lung adenocarcinoma in vivo and that higher expression is associated with decreased overall and disease-free survival. Conclusion: SHMT2 was identified as a novel target to overcome treatment resistance in human lung adenocarcinoma, which may be regulated ferroptotic cell death. Citation Format: Kunal R. Chaudhary, Connor J. Kinslow, Ling F. Ye, Pavan S. Upadhyayula, Eun Y. Lee, Ramon C. Sun, Simon K. Cheng. Serine hydroxymethyltransferase-2 as regulator of oxidative stress and chemoradiation resistance in lung adenocarcinoma [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 1992.