双歧杆菌对实验性大肠癌的预防及诱导细胞凋亡的作用

目的　探讨青春型双歧杆菌对实验性大肠癌的预防作用及其防瘤机制。方法　以裸鼠大肠癌移植瘤为动物模型,预先用双歧杆菌注射于裸鼠腹腔,观察移植瘤的生长速度,同时利用透射电镜、原位末端标记技术及免疫组化技术观察大肠癌裸鼠移植瘤的超微结构、凋亡细胞密度以及ｂｃｌ２、ｂａｘ 蛋白表达率及其阳性细胞密度。结果　双歧杆菌预防组大肠癌移植瘤的生长速度显著慢于对照组; 此外双歧杆菌预防组移植瘤组织中可见多量处于不同凋亡时期的瘤细胞,其凋亡细胞密度、ｂａｘ 蛋白表达率以及阳性细胞密度均显著高于肿瘤对照组,而ｂｃｌ２ 蛋白的表达情况则相反。结论　青春型双歧杆菌能显著预防大肠癌的发生与发展,并能诱导其细胞凋亡。

Roles of bifidobacterium on prevention of experimental colorectal carcinoma and induction of apoptosis

Objective To explore the effect of bifidobacterium adolescence on prevention from experimental colorectal carcinoma and its antitumor mechanism. Methods An animal model of nude mouse tumor transplanted from colorectal carcinoma was set up. Bifidobacteria adolescence were intraperitoneally injected into nude mice in advance. The growth rate, ultrastructure, density of apoptotic cells, rate of bcl 2 and bax oncoprotein expression and its positive cell density in transplanted tumor of nude mice from colorectal carcinoma were investigated by employing transmission microscopy, in situ end labeling technique and immunohistochemical staining. Results The growth rate of transplanted tumors from colorectal carcinoma in the group with bifidobacterium prevention was slower than that in the control group. Many tumor cells at varied apoptotic stages could be observed in transplantation tumor tissue in the bifidobacterium prevention group and their density of apoptotic cells, rate of bcl 2 and bax oncoprotein expression and its positive cell density were significantly higher in the group with bifidobacterium prevention, as compared with the control group ( P <0.01). But, expression rate of bcl 2 oncoprotein turned contrary to that of bax oncoprotein. Conclusion Bifidobacteria adolecence could markedly prevent from occurrence and development of colorectal carcinoma in vivo and induce apoptosis of tumor.