两歧双歧杆菌胞外多糖对胃癌细胞及hTERT的影响

【目的】研究从双歧杆菌属两歧双歧杆菌(Bifidobacterium bifidum)提取的细胞表面成分胞外多糖(Exopolysaccharide, B.EPS)对人胃癌细胞BGC-823的生长抑制作用及对端粒酶限速因子hTERT活性的影响。【方法】将三种不同浓度B.EPS体外作用于胃癌细胞BGC823，MTT法检测细胞生长抑制率并辅以形态学观察；异硫氰酸盐(FITC)联合PI染色，通过流式细胞术检测肿瘤细胞初期调亡情况；肿瘤细胞端粒酶限速因子hTERT mRNA经RT-PCR检测B.EPS对端粒酶活性抑制作用；通过荧光分光光度计显示B.EPS 对胃癌细胞作用后胞内Ca2+含量变化。【结果】经过检测发现，B.EPS对人胃癌细胞BGC823的生长显著抑制(P＜0.05)呈剂量时间反应关系；细胞中hTERT mRNA在B.EPS的作用下表达降低(P＜0.05)，有一定剂量效应关系；随着B.EPS对肿瘤细胞的抑制，细胞内Ca2+含量显著增加(P＜0.05)。【结论】B.EPS诱导人胃癌细胞BGC823调亡的机制可能与改变肿瘤细胞端粒酶限速因子hTERT mRNA表达量和细胞内钙离子浓度有关。

Effect of exopolysaccharide from Bifidobacterium bifidum on cell of gastric cancer and hTERT

Objective] To study the inhibition of human gastric cancer cell BGC823 by exopolysaccharide (B. EPS) extracted from Bifidobacterium bifidum and the effect on the activity of telomerase rate-limiting factor hTERT. Methods] The B. EPS was divided into three groups by multiplication concentration level which effected on human gastric cancer cell BGC823 in vitro, the inhibition rate of gastric cancer cell BGC-823, the morphology changes of cells and the apoptosis in the initial stage of cell was observed respectively by MTT, inverted fluorescent microscope and the Annexin V-FITC/PI flow cytometry. In addition, the effect of B.EPS on cell telomerase rate-limiting factor hTERT mRNA was tested by RT-PCR; the changes in the concentration of calcium ions inside the cytoplasm were detected by spectrofluorometer. Results] B.EPS inhibited the growth of gastric cancer cell BGC-823 (P<0.05), the inhibition rate increased and the concentration of B.EPS showed dose-time response relation. The expression of cell telomerase rate-limiting factor hTERT mRNA decrease after effected by B.EPS (P<0.05), and showed dose-effect relation. The concentration of calcium ion in cytoplasm was higher than the control apparently (P<0.05). Conclusion] The apoptosis mechanism of human gastric cancer cell BGC823 induced by B.EPS may be relevant with the expression of hTERT mRNA and the concentration of calcium ions in cytoplasm.