Neurokinin-1 receptor promotes non-small cell lung cancer progression through transactivation of EGFR.

Despite the great advances in target therapy, lung cancer remains the top cause of cancer-related death worldwide. G protein-coupled receptor neurokinin-1 (NK1R) is shown to play multiple roles in various cancers; however, the pathological roles and clinical implication in lung cancer are unclarified. Here we identified NK1R as a significantly upregulated GPCR in the transcriptome and tissue array of human lung cancer samples, associated with advanced clinical stages and poor prognosis. Notably, NK1R is co-expressed with epidermal growth factor receptor (EGFR) in NSCLC patients' tissues and co-localized in the tumor cells. NK1R can crosstalk with EGFR by interacting with EGFR, transactivating EGFR phosphorylation and regulating the intracellular signaling of ERK1/2 and Akt. Activation of NK1R promotes the proliferation, colony formation, EMT, MMP2/14 expression, and migration of lung cancer cells. The inhibition of NK1R by selective antagonist aprepitant repressed cell proliferation and migration in vitro. Knockdown of NK1R significantly slowed down the tumor growth in nude mice. The sensitivity of lung cancer cells to gefitinib/osimertinib is highly increased in the presence of the selective NK1R antagonist aprepitant. Our data suggest that NK1R plays an important role in lung cancer development through EGFR signaling and the crosstalk between NK1R and EGFR may provide a potential therapeutic target for lung cancer treatment.

Inhibition of autophagy by YC-1 promotes gefitinib induced apoptosis by targeting FOXO1 in gefitinib-resistant NSCLC cells.

Non-small cell lung cancer (NSCLC) is the most common cancer in the world. Gefitinib, an inhibitor of EGFR tyrosine kinase, is highly effective in treating NSCLC patients with activating EGFR mutations (L858R or Ex19del). However, despite excellent disease control with gefitinib therapy, innate resistance and inevitable acquired resistance represent immense challenges in NSCLC therapy. Gefitinib potently induces cytoprotective autophagy, which has been implied to contribute to both innate and acquired resistance to gefitinib in NSCLC cells. Currently, abrogation of autophagy is considered a promising strategy for NSCLC therapy. In the present study, YC-1, an inhibitor of HIF-1α, was first found to significantly inhibit the autophagy induced by gefitinib by disrupting the fusion of autophagosomes and lysosomes and thereby enhancing the proapoptotic effect of gefitinib in gefitinib-resistant NSCLC cells. Furthermore, the combinational anti-autophagic and pro-apoptotic effect of gefitinib and YC-1 was demonstrated to be associated with an enhanced of forkhead box protein O1 (FOXO1) transcriptional activity which resulted from an increase in the p-FOXO1 protein level in gefitinib-resistant NSCLC cells. Our data suggest that inhibition of autophagy by targeting FOXO1 may be a feasible therapeutic strategy to overcome both innate and acquired resistance to EGFR-TKIs.

YC-1 potentiates the antitumor activity of gefitinib by inhibiting HIF-1α and promoting the endocytic trafficking and degradation of EGFR in gefitinib-resistant non-small-cell lung cancer cells.

The tyrosine kinase inhibitor (TKI) gefitinib exerts good therapeutic effect on NSCLC patients with sensitive EGFR-activating mutations. However, most patients ultimately relapse due to the development of drug resistance after 6-12 months of treatment. Here, we showed that a HIF-1α inhibitor, YC-1, potentiated the antitumor efficacy of gefitinib by promoting EGFR degradation in a panel of human NSCLC cells with wild-type or mutant EGFRs. YC-1 alone had little effect on NSCLC cell survival but significantly enhanced the antigrowth and proapoptotic effects of gefitinib. In insensitive NSCLC cell lines, gefitinib efficiently inhibited the phosphorylation of EGFR but not the downstream signaling of ERK, AKT and STAT3; however, when combined with YC-1 treatment, these signaling pathways were strongly impaired. Gefitinib treatment induced EGFR arrest in the early endosome, and YC-1 treatment promoted delayed EGFR transport into the late endosome as well as receptor degradation. Moreover, the YC-1-induced reduction of HIF-1α protein was associated with the enhancement of EGFR degradation. HIF-1α knockdown promoted EGFR degradation, showing synergistic antigrowth and proapoptotic effects similar to those of the gefitinib and YC-1 combination treatment in NSCLC cells. Our findings provide a novel combination treatment strategy with gefitinib and YC-1 to extend the usage of gefitinib and overcome gefitinib resistance in NSCLC patients.