Thioridazine reverses trastuzumab resistance in gastric cancer by inhibiting S-phase kinase associated protein 2-mediated aerobic glycolysis

Figure 1 Elevated S-phase kinase associated protein 2 expression contributes to trastuzumab resistance in human epidermal growth factor receptor 2-positive gastric cancer cells. A: Western blotting was used to measure the S-phase kinase associated protein 2 (Skp2) expression level in human gastric cancer (GC) cell lines; B and C: Skp2 expression in HGC27 and HGC27-R cells and SGC7901 and SGC7901-R cells was analyzed by Western blotting; D: Skp2 expression levels in HGC27 cells transfected with empty vector (pcDNA3.1), OX-SKP2-1 or OX-SKP2-2 (pcDNA3.1/SKP2) were determined by western blotting; E: HGC27 cells stably transfected with empty vector or OX-SKP2-2 were cultured with or without trastuzumab (0, 2.5, 5, and 10 μg/mL) for 48 h. Proliferation activity was analyzed by cell counting kit-8 (CCK-8) assays; F: HGC27-R cells were transfected with or without small interfering RNA-negative control (siRNA-NC) or siRNA-SKP2 for 72 h. Skp2 expression was measured by western blotting; G: HGC27 cells transfected with siRNA-NC or siRNA-SKP2-2 were cultured with or without 10 μg/mL trastuzumab. CCK-8 assays were used to analyze proliferation activity. The experiments were performed in triplicate. ^bP < 0.01; ^cP < 0.001; ^dP < 0.0001. Skp2: S-phase kinase associated protein 2; siRNA: Small interfering RNA; NC: Negative control.