The HDAC inhibitor GCJ-490A suppresses c-Met expression through IKKα and overcomes gefitinib resistance in non-small cell lung cancer

Objective:The novel compound GCJ-490A has been discovered as a pan-histone deacetylase(HDAC)inhibitor that exerts potent inhibitory activity against HDAC1,HDAC3,and HDAC6.Because of the important roles of HDACs in lung cancer development and the high distribution of GCJ-490A in lung tissue,we explored the anti-tumor potency of GCJ-490A against non-small cell lung cancer(NSCLC)in vitro and in vivo in this study.Methods:The in vitro effects of GCJ-490A alone or combined with the EGFR inhibitor gefitinib against NSCLC were measured with proliferation,apoptosis,and colony formation assays.NSCLC xenograft models were used to investigate the efficacy of GCJ-490A combined with gefitinib for the treatment of NSCLC in vivo.Western blot assays,luciferase reporter assays,chromatin immunoprecipitation assays,quantitative real time-PCR,immunohistochemistry,and transcription factor activity assays were used to elucidate possible mechanisms.Results:GCJ-490A effectively inhibited NSCLC cell proliferation and induced apoptosis in vitro and in vivo.Interestingly,inhibition of HDAC1 and HDAC6 by GCJ-490A increased histone acetylation at the IKKαpromoter and enhanced IKKαtranscription,thus decreasing c-Met.Moreover,this c-Met downregulation was found to be essential for the synergistic anti-tumor activity of GCJ-490A and gefitinib.Conclusions:These findings highlight the promising potential of HDAC inhibitors in NSCLC treatment and provide a rational basis for the application of HDAC inhibitors in combination with EGFR inhibitors in clinical trials.