Pretreatment with Gemcitabine/5-Fluorouracil Enhances the Cytotoxicity of Trastuzumab to HER2-Negative Human Gallbladder Cancer Cells In Vitro and In Vivo

Figure 2

Cell viability inhibition rates and apoptosis in GBC cell lines after treatment with various drugs. (a) Cell viability inhibition rates in NOZ cells and GB-D1 cells after treatment with trastuzumab (Herceptin, H) only, chemotherapy (GEM, G and 5-Fu, F) only, sequential therapy with chemotherapy followed by trastuzumab, concomitant therapy with chemotherapy and trastuzumab, and sequential therapy with trastuzumab followed by chemotherapy were evaluated. Sequential therapy with chemotherapy followed by trastuzumab demonstrated superiority over the others. P > 0.05. Others: P < 0.05. Cell viability inhibition rate was calculated as follows: (nontreated cells OD - treated cells OD) / (nontreated cells OD - blank OD). (b) Results relating to apoptosis in NOZ cells were similar to those of the cell viability assay. Sequential therapy with chemotherapy followed by trastuzumab demonstrated superiority over the others in terms of apoptosis. P > 0.05. Others: P < 0.05. (c) Effects of trastuzumab and/or GEM on cell cycle in NOZ cells: P > 0.05, G versus (H + G) in the G1 phase of the cell cycle; control versus H, and G versus (H + G) in the S phase of the cell cycle, all in the G2 phase of the cell cycle. Others: P < 0.05. Effects of trastuzumab and/or 5-Fu on cell cycle in NOZ cells: P > 0.05: H versus (HF), and (H + F) versus (FH) in the G1 phase of the cell cycle; control versus H, control, H or F versus (HF) in the S phase of the cell cycle; control versus H, H versus F, (FH) versus (H + F), control, H or F versus (HF) in the G2 phase of the cell cycle. Others: P < 0.05. (d) Western blots were performed to detect the effects of trastuzumab and/or chemotherapeutic drugs on the expressions of key proteins HER2, pHER2, AKT, and pAKT in the HER2/AKT signaling pathway in NOZ cells. β-actin was used as a loading control. NOZ cells showed increases in pHER2, pAKT, HER2, and AKT expression following G/F alone or HG/F treatment.

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