Abstract 3000: Ferroptosis evasion as a therapeutic strategy in STK11/KEAP1 co-mutant lung adenocarcinoma
Authors: Durani Vidushi , Wohlhieter Corrin A. , Quintanal-Villalonga Alvaro , Sen Triparna , Manoj Parvathy , Rudin Charles M. 
Published: June 2022

Introduction Lung adenocarcinoma (LUAD) is the most common histological subtype of lung cancer, accounting for almost 50% of lung cancer cases. Comprehensive molecular characterization of LUAD tumors has identified actionable drivers and led to the development of targeted inhibitors that have substantially improved patient survival. Our team previously showed that concomitant mutational inactivation of Serine/Threonine Kinase 11 (STK11) and Kelch-like ECH Associated Protein1 (KEAP1), found in up to 10% of LUAD cases, enhances cell proliferation and invasion in vitro and in vivo. Bulk RNA sequencing identified upregulation of genes involved in ferroptosis, an iron-dependent form of programmed cell death, in STK11/KEAP1 double mutant models, nominating ferroptosis as a potential vulnerability in these tumors. Consistently, CRISPR/Cas9 based genetic screening identified stearoyl-CoA desaturase (SCD), a gene involved in ferroptosis protection, as a therapeutic target in the STK11/KEAP1 double mutant tumors. However, the mechanism of ferroptosis evasion in this subset in not well understood.

Methods To further characterize the role of ferroptosis regulators in STK11/KEAP1 co-mutant setting, we performed phospho-kinase arrays and RNA sequencing in STK11/KEAP1 cell lines followed by validation through western blotting. We also performed gene expression analysis in patient derived xenografts (PDX) models treated with the SCD inhibitor to further characterize potential mechanisms by which SCD inhibition has synthetic lethal effects in STK11/KEAP1 co-mutant tumors.

Results We demonstrate that SCD overexpression protects STK11/KEAP1 co-mutant LUADs from undergoing ferroptosis. Pharmacological inhibition of SCD significantly reduced viability of STK11/KEAP1 co-mutant LUADs and made the co-mutant cells sensitive to ferroptosis induction. Phospho-kinase arrays revealed decreased activation of the JAK-STAT and AKT signaling pathways in STK11/KEAP1-double KO LUADs models as compared to either STK11 or KEAP1 single mutant isogenic conditions, which was confirmed by RNA sequencing data showing downregulation of genes involved in these pathways specifically in the double knockout setting. Interestingly, SCD pharmacological inhibition by CVT-11127 reversed this phenotype and induced overexpression of genes involved in both pathways. Additionally, SCD genetic knock out in STK11/KEAP1-double KO LUADs models mimicked the effects observed after SCD pharmacological inhibition, supporting that these were derived from on-target drug action.

Conclusions To summarize, these results suggest a potential interplay between STK11/KEAP1 function loss, ferroptosis protection, and the JAK-STAT and AKT oncogenic signaling pathways in LUAD. Further study of the role of these signaling pathways in ferroptosis may reveal mechanistic insight into the aggressive nature of these tumors.

Citation Format: Vidushi Durani, Corrin A. Wohlhieter, Alvaro Quintanal-Villalonga, Triparna Sen, Parvathy Manoj, Charles M. Rudin. Ferroptosis evasion as a therapeutic strategy in STK11/KEAP1 co-mutant lung adenocarcinoma [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 3000.