Inhibitor of ghrelin receptor reverses gefitinib resistance in lung cancer.

Gefitinib is the first-generation EGFR tyrosine kinase inhibitor (EGFR-TKI), which is used in the treatment of NCSLC patients through interrupting EGFR signaling pathway. Although gefitinib prolongs patients' progression-free survival (PFS), acquired resistance occurs in advanced NSCLC patients. In this study, we mainly investigated the effects of antagonist for ghrelin-R (D-lys-3-GHRP-6) on conquering acquired gefitinib resistance in human lung cancer cells. We found that GHSR was overexpressed in our established HCC827/GR cells compared with parental cells, accompanied with increase of p-AKT and p-ERK1/2. Treatment of D-lys-3-GHRP-6 significantly decreased p-AKT and p-ERK1/2 expression in HCC827/GR cells. H1650 cells and HCC827/GR cells were treated with control, gefitinib, D-lys-3-GHRP-6 and D-lys-3-GHRP-6 + gefitinib, respectively. In H1650 and HCC827/GR cells, combination of D-lys-3-GHRP-6 and gefitinib significantly inhibited cell proliferation and Bcl2 protein level, induced the cell apoptosis and cleaved-caspase3 protein level compared with control group, while there was no significant difference between control and gefitinib group.