LAPTM4B Confers Resistance to EGFR-TKIs by Suppressing the Proteasomal Degradation of ATP1A1 in Non-small Cell Lung Cancer.

Tyrosine kinase inhibitors (TKIs) have transformed the treatment of EGFR-mutant non-small cell lung cancer (NSCLC); however, acquired resistance remains a major clinical challenge. While lysosomes have been implicated in drug resistance, their precise role in EGFR-TKI resistance remains unclear. In this study, we found that EGFR-TKI, including gefitinib and osimertinib, impaired WWP2-mediated proteasomal degradation of LAPTM4B. Through analysis of clinical tumor samples, genetic manipulation, and functional assays, we identify the lysosomal protein LAPTM4B as a key driver of EGFR-TKI resistance by enhancing EGFR phosphorylation and downstream signaling. Mechanistically, LAPTM4B interacts with ATP1A1 and facilitates its endocytosis, while simultaneously preventing its degradation by suppressing TRIM8-mediated K63-linked ubiquitination and proteasomal turnover. This stabilization of ATP1A1 enhances lysosomal acidification, ultimately promoting EGFR-TKI resistance. To identify potential therapeutic strategies, we conducted an unbiased high-content drug screen and identified compounds that suppress LAPTM4B expression. These compounds synergistically enhance the efficacy of EGFR-TKIs in NSCLC models