Abstract
Background The oncogenic protein, MET (or c-MET), is involved in the positive regulation of cell survival and proliferation and in mediating acquired resistance to EGFR-TKIs including AZD9291 (osimertinib). Thus, MET inhibition is a promising strategy for overcoming acquired EGFR-TKI resistance due to MET amplification. HQP8361 (MK8033) is a novel and selective MET kinase inhibitor that has completed a phase I clinical trial. The current study focuses on determining the activity and mechanism of action of HQP8361 as a single agent and in combination with AZD9291 against human NSCLC cells, particularly EGFR-mutant NSCLCs with acquired resistance to AZD9291. Methods Drug effects on cell growth in vitro were evaluated by measuring cell number alterations and colony formation and in vivo with mouse xenogtaft models, respectively. Apoptosis was assessed with annexin V/flow cytomentry and protein cleavage. Protein alterations were detected with Western blotting. Protein degradation was determined by comparing protein half-lives and inhibiting proteasome. Gene overexpression and knockout were achieved with lentiviral infection and CRISPR/Cas9, respectively. Significance of differences between two tested groups was analyzed with two-sided unpaired Student's t tests. Results The majority of human NSCLC cell lines tested, including those harboring EGFR-activating mutations with acquired resistance to AZD9291, had very low or undetectable levels of MET and p-MET and were insensitive to HQP8361. However, AZD9291-resistant (AR) cell lines derived from the EGFR-mutant HCC827 cell line possessed high levels of MET and p-MET and responded to HQP8361 single agent and particularly to the combination of HQP8361 and AZD9291. The HQP8361 and AZD9291 combination synergistically decreased the survival of these HCC827/AR cell lines with enhanced induction of apoptosis that involved alteration of Bim and Mcl-1 levels via modulating their degradation. Moreover, the combination also very effectively inhibited the growth of HCC827/AR xenografts in nude mice. Conclusions These preclinical findings support the potential of HQP8361 in the treatment of NSCLCs with MET amplification or highly activated MET protein and, when combined with AZD9291, in overcoming acquired resistance to EGFR-TKIs due to MET amplification.
Dual HER2/PIK3CA Targeting Overcomes Single-Agent Acquired Resistance in HER2-Amplified Uterine Serous Carcinoma Cell Lines In Vitro and In Vivo