DYRK1A suppression restrains Mcl-1 expression and sensitizes NSCLC cells to Bcl-2 inhibitors

摘要

Objective:Mcl-1 overexpression confers acquired resistance to Bcl-2 inhibitors in non-small cell lung cancer(NSCLC),but no direct Mcl-1 inhibitor is currently available for clinical use.Thus,novel therapeutic strategies are urgently needed to target Mcl-1 and sensitize the anti-NSCLC activity of Bcl-2 inhibitors.Methods:Cell proliferation was measured using sulforhodamine B and colony formation assays,and apoptosis was detected with Annexin V-FITC staining.Gene expression was manipulated using siRNAs and plasmids.Real-time PCR and Western blot were used to measure mRNA and protein levels.Immunoprecipitation and immunofluorescence were used to analyze co-localization o f dual specificity tyrosine-phosphorylation-regulated kinase 1A(DYRK1A)and Mcl-1.Results:Suppression of DYRK1A resulted in reduced Mcl-1 expression in NSCLC cells,whereas overexpression of DYRK1A significantly increased Mcl-1 expression.Suppression of DYRK1A did not alter Mcl-1 mRNA levels,but did result in an accelerated degradation o f Mcl-1 protein in NSCLC cells.Furthermore,DYRK1A mediated proteasome-dependent degradation o f Mcl-1 in NSCLC cells,and DYRK1A co-localized with Mcl-1 in NSCLC cells and was co-expressed with Mcl-1 in tumor samples from lung cancer patients,suggesting that Mcl-1 may be a novel DYRK1A substrate.We showed that combined therapy with harmine and Bcl-2 antagonists significantly inhibited cell proliferation and induced apoptosis in NSCLC cell lines as well as primary NSCLC cells.Conclusions:Mcl-1 is a novel DYRK1A substrate,and the role of DYRK1A in promoting Mcl-1 stability makes it an attractive target for decreasing Bcl-2 inhibitor resistance.