Oncogenic KRAS induces arginine auxotrophy in non-small cell lung cancer and confers a therapeutic vulnerability to SLC7A1 inhibition
The urea cycle is frequently rewired in cancer cells to meet the metabolic demands of cancer, yet our understanding about the regulatory mechanisms for this pathway in different types of cancer is very limited. In this study, we discover that oncogenic activation of KRAS in non-small cell lung cancer (NSCLC) silences the expression of arginosuccinate synthase 1 (ASS1), a urea cycle enzyme catalyzing the production of arginine from aspartate and citrulline, and thereby diverts the utilization of aspartate to pyrimidine synthesis to meet the high demand for DNA replication in KRAS-mutant NSCLC. Specifically, KRAS signaling facilitates a hypo-acetylated state in the promoter region of ASS1 gene in a histone deacetylase 3 (HDAC3)-dependent manner, which in turn impedes the recruitment of the transcription factor c-MYC for ASS1 transcription. ASS1 suppression in KRAS-mutant NSCLC cancer cells impairs the biosynthesis of arginine and renders growth dependency on SLC7A1, an arginine transmembrane transport, to import extracellular arginine. Depletion of SLC7A1 in both patient-derived organoid and xenograft models obtains a substantial therapeutic benefit in inhibiting KRAS-driven NSCLC growth. Together, our findings uncover a new role of oncogenic KRAS in rewiring urea cycle metabolism and identify SLC7A1-mediated arginine uptake as a therapeutic vulnerability in treating KRAS-mutant NSCLC. Overall design: To investigate how oncogenic KRAS rewires metabolic enzymes in the urea cycle, we introduced KRAS-G12D mutant into human bronchial epithelial BEAS-2B cells (BEAS-2B-KRAS-G12D). We then performed gene expression profiling analysis using data obtained from RNA-seq of BEAS-2B-EV and BEAS-2B-KRAS-G12D.