ABSTRACT
OBJECTIVE Identification of novel autophagy inhibitors for the combinational treatment of non-small cell lung cancer (NSCLC). METHODS MTT assay and annexin V/PI staining assay were used to evaluate the cell proliferation and apoptosis, respectively. Immunofluorescence staining and cathepsin activity assay were used to detect autophagy. Small interfering RNA was performed to silence the genes and Western blot assay was used to evaluate the protein express levels. Xenograft experiments were applied for in vivo evaluation. RESULTS Cepharanthine, a natural compound, increased LC3-II expression and GFP-LC3 puncta formation in NSCLC NCI-H1975 cells. Numerous yellow puncta were observed in cepharanthine- treated cells with mRFP- EGFP- LC3 transfection. Co-staining of GFP-LC3 with LysoTracker red or LAMP1 antibody suggested that cepharanthine inhibits autophagosomes- lysosomes fusion. Moreover, cepharanthine attenuated the lysosomal cathepsins maturation. We also confirmed that dacomitinib induced cytoprotective autophagy. Combined treatment with cepharanthine increased the anti- cancer effects of dacomitinib in vitro and in vivo. Besides, cepharanthine could not enhance the anti-cancer effect of dacomitinib in autophagy deficient cells. CONCLUSION Cepharanthine might be further developed as a promising autophagic inhibitor, and combined treatment cepharanthine with dacomitinib could pose as an effective strategy for NSCLC treatment.