Branched-chain amino acid transaminase 1 confers EGFRTKI resistance through epigenetic glycolytic activation

Third-generation EGFR tyrosine kinase inhibitors(TKIs),exemplified by osimertinib,have demonstrated promising clinical efficacy in the treatment of non-small cell lung cancer(NSCLC).Our previous work has identified ASK120067 as a novel third-generation EGFR TKI with remarkable antitumor effects that has undergone New Drug Application(NDA)submission in China.Despite substantial progress,acquired resistance to EGFR-TKIs remains a significant challenge,impeding the long-term effectiveness of therapeutic approaches.In this study,we conducted a comprehensive investigation utilizing high-throughput proteomics analysis on established TKI-resistant tumor models,and found a notable upregulation of branched-chain amino acid transaminase 1(BCAT1)expression in both osimertinib-and ASK120067-resistant tumors compared with the parental TKI-sensitive NSCLC tumors.Genetic depletion or pharmacological inhibition of BCAT1 impaired the growth of resistant cells and partially re-sensitized tumor cells to EGFR TKIs.Mechanistically,upregulated BCAT1 in resistant cells reprogrammed branched-chain amino acid(BCAA)metabolism and promoted alpha ketoglutarate(α-KG)-dependent demethylation of lysine 27 on histone H3(H3K27)and subsequent transcriptional derepression of glycolysis-related genes,thereby enhancing glycolysis and promoting tumor progression.Moreover,we identified WQQ-345 as a novel BCAT1 inhibitor exhibiting antitumor activity both in vitro and in vivo against TKI-resistant lung cancer with high BCAT1 expression.In summary,our study highlighted the crucial role of BCAT1 in mediating resistance to third-generation EGFR-TKIs through epigenetic activation of glycolysis in NSCLC,thereby supporting BCAT1 as a promising therapeutic target for the treatment of TKI-resistant NSCLC.