Study on the effects of 3-bromopyruvate on the sensitivity of human nasopharyngeal carcinoma cells to cisplatin and its mechanism

ObjectiveTo investigate the effect of 3-bromopyruvate (3-BrPA) on enhancing the sensitivity of human nasopharyngeal carcinoma cells to cisplatin and its mechanism.

MethodsThe effects of 3-BrPA and cisplatin on the proliferation of nasopharyngeal carcinoma HNE1 cells were detected by MTT assay.The effects of 3-BrPA and cisplatin on the colony forming ability of HNE1 cells were observed using colony formation assay.The early apoptosis was analyzed by mitochondrial membrane potential detection kit.The nuclear morphological changes were detected by DAPI fluorescence staining.The apoptosis rate was detected by Annexin Ⅴ-FITC/PI double staining.The changes of intracellular ATP level were measured by ATP detection kit.The protein expressions of Bcl-2, Bax, Mcl-1 and Bak were analyzed by Western blotting.

Results3-BrPA (20, 40, 80, 160 and 320 μmol/L), cisplatin (2, 4, 8, 16 and 32 μmol/L) and 80 μmol/L 3-BrPA combined with different concentrations of cisplatin significantly inhibited the proliferation of HNE1 cells in vitro, which was statistically significant compared with control group (P < 0.01).The combination of 8 μmol/L 3-BrPA and 0.8 μmol/L cisplatin significantly decreased the colony formation of HNE1 cells compared with that of 3-BrPA or cisplatin alone and control group (P < 0.01).The transformation of red fluorescence to green fluorescence was obvious, and nuclear fragmentation and nuclear pyknosis increased significantly in 80 μmol/L 3-BrPA combined with 8 μmol/L cisplatin group.The apoptosis rate and intracellular ATP level in 80 μmol/L 3-BrPA combined with 8 μmol/L cisplatin group were significantly higher and lower than those in 3-BrPA or cisplatin alone group and control group, respectively (P < 0.01).The expression levels of Bcl-2 and Mcl-1 protein were significantly downregulated, and the expression levels of Bax and Bak protein were significantly upregulated in 80 μmol/L 3-BrPA combined with 8 μmol/L cisplatin group, which was statistically significant compared with 3-BrPA or cisplatin alone group and control group (P < 0.05 to P < 0.01).

Conclusions3-BrPA can induce apoptosis in HNE1 cells and enhance the sensitivity of HNE1 cells to cisplatin.The mechanism of which may be related to the decrease of intracellular ATP level, down-regulation of Mcl-1 and Bcl-2 protein, and up-regulation of Bak and Bax protein.