pSTAT3 transactivates EGFR in maintaining EGFR protein homeostasis and EGFR-TKI resistance.

EGFR protein trafficking is critical for regulating multiple biological processes, including cell growth and survival. However, how EGFR protein homeostasis is maintained remains unclear. In this study, we show that a reduction in plasma membrane-associated EGFR triggers EGFR transcription by promoting pSTAT3 nuclear localization. Nucleus-localized pSTAT3 binds to the EGFR gene promoter to transactivate EGFR. Moreover, erlotinib, an EGFR tyrosine kinase inhibitor (TKI), can also increase pSTAT3 nuclear accumulation, resulting in increased EGFR transcription and erlotinib resistance. Importantly, pharmacological inhibition of pSTAT3 can significantly overcome the resistance of cancer cells to erlotinib. Together, these findings demonstrate that pSTAT3 is pivotal for maintaining EGFR protein homeostasis and suggest that activation of the pSTAT3-EGFR axis contributes to EGFR-TKI resistance.