Melatonin

Melatonin (purity >99%) was obtained from Santa Cruz Biotechnology (Santa Cruz, CA, USA). It was dissolved in dimethyl sulfoxide (DMSO) and diluted with culture medium to the aimed concentration on experimental day. The final concentration of DMSO for all treatments was consistently less than 0.1%. Cell culture reagents were obtained from Invitrogen (Carlsbad, CA, USA). The VCR, Coomassie brilliant blue, MTT, 4′,6-diamidino-2-phenylindole (DAPI) dye, protease inhibitor cocktail, phosphatase inhibitor cocktail, and AO were purchased from Sigma-Aldrich (St. Louis, MO, USA). Negative inhibitor (miRNA inhibitor negative control), miRNA-34b-5p inhibitor, and miRNA-892a inhibitor were purchased from Clontech (CA, USA). Antibody against cleaved PARP, cleaved caspase-3, -9, LC3, SQSTM1, Beclin-1, ABCB1, ABCG2, p-AKT, AKT, p-ERK1/2, ERK1/2, p-p38, p38, p-JNK1/2, JNK1/2, and β-actin were purchased from Cell Signaling Technology (Danvers, MA, USA). Antibody against ABCB4 was obtained from MyBioSource (San Diego, CA, USA). Specific inhibitors for AKT inhibitor (LY294002), ERK1/2 (U0126), p38 MAPK (SB203580), JNK (SP600125), wortmannin, bafilomycin A1 (Baf A1), and z-VAD-FMK were obtained from Santa Cruz Biotechnology (Santa Cruz, CA, USA).