CLOCK confers EGFR-TKIs resistance in non-small cell lung cancer by transcriptionally upregulating LAMC2 expression and activating multiple kinase signaling.

Abstract

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) represents a major clinical challenge in the management of non-small cell lung cancer (NSCLC). Chromosome 4q12 locus is an important gene locus associated with progression-free survival (PFS) in NSCLC patients receiving EGFR-TKIs therapy. However, it remains poorly characterized how genes at this locus function in NSCLC development and resistance to EGFR-TKIs. Here, we found that CLOCK at this locus is highly expressed in NSCLC tissues and correlates with unfavorable PFS of patients. CLOCK promotes malignant proliferation and metastasis of NSCLC in vitro and in vivo. CLOCK could attenuate treatment efficacies of gefitinib (one of the first-generation EGFR-TKIs) or osimertinib (one of the third-generation EGFR-TKIs). Mechanistically, CLOCK functions as a transcriptional factor to upregulate LAMC2 transcription and expression in NSCLC cells. There was significantly elevated LAMC2 expressed in NSCLC tissues and its high levels were associated with shortened survival of patients. Indeed, CLOCK could activate multiple kinase signaling pathways, such as the PI3K-Akt signaling and the MAPK signaling, by facilitating either the LAMC2-ITGB1 interaction and the LAMC2-EGFR interaction and thereby accelerating NSCLC proliferation and conferring EGFR-TKI resistance. Collectively, these findings for the first time identify CLOCK as a critical mediator of EGFR-TKIs resistance and a promising target to overcome EGFR-TKIs resistance in NSCLC.