Abstract

Intrinsic and acquired resistance represent major obstacles to optimize outcomes in epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) targeted therapy in lung adenocarcinoma (LUAD). Hence, a deeper understanding of EGFR-TKI resistance mechanisms in LUAD will potentially assist in formulating strategies to delay or overcome such resistance. Herein, it was observed that trefoil factor 3 (TFF3) is a crucial mediator of the LUAD EGFR-TKI response. TFF3 conferred intrinsic resistance to EGFR inhibition in LUAD by promotion of EGFR activation. TFF3 expression was also increased in acquired EGFR-TKI resistant LUAD, accompanied by reduced EGFR activation. YAP, a key mediator of the Hippo signaling, was positively regulated by TFF3 by post-transcriptional mechanisms and was responsible for acquired EGFR-TKI resistance mediated by TFF3. Inhibition of TFF3 by a small molecule inhibitor not only enhanced EGFR-TKI sensitivity in LUAD cells but also restored the sensitivity of acquired EGFR-TKI resistant LUAD cells to EGFR-TKIs in vitro and in vivo. These findings demonstrate a pivotal function of TFF3 in mediating both intrinsic and acquired EGFR-TKI resistance in LUAD and may offer a potential therapeutic mechanism for delaying or overcoming resistance to EGFR-TKIs.