Inhibition of GSTO1-TNFαIP3/A20 interaction sensitizes MDR HCT-116 cells to cisplatin. (A) Co-IP was used to determine the interaction of endogenous GSTO1 and TNFαIP3/A20 in the whole cell lysate of MDR HCT116 cells. (B) Western blotting and (C) densitometric analysis showing that TNFαIP3/A20 expression was increased in MDR cells compared with the WT cells irrespective of treatments; one-way ANOVA was used for statistical analysis. (D) GSTO1 pull-down, western blotting for TNFαIP3/A20 and (E) densitometric analysis showing that the GSTO1-TNFαIP3/A20 interaction is increased in MDR cells compared with WT cells irrespective of treatments; one-way ANOVA was used for statistical analysis. (F) GSTO1 co-IP in cis-treated Mock and GSTO1-KD MDR cells shows that the GSTO1-TNFαIP3/A20 interaction is reduced in GSTO1-KD cells. (G) Representative western blotting images of GSTO1, TNFαIP3/A20 and apoptosis- and autophagy-related protein markers in GSTO1 and TNFαIP3/A20 single-KD and double-KD MDR cells showing that the double KD had a more notable effect compared with either single KD. *P<0.05; **P<0.01. GSTO1, glutathione-S-transferase Ω-1; cas, caspase; cis, cisplatin; IB, immunoblot; IP, immunoprecipitation; KD, knockdown; MDR, multidrug resistant; ns, not significant; TNFαIP3/A20, TNF-α-induced protein 3/zinc-finger protein A20; veh, vehicle; WT, wild-type.