双歧杆菌的完整肽聚糖对实验性大肠癌的抑制作用及诱导其凋亡

The inhibition of whole peptidoglycan of bifidobacterium in experimental colorectal carcinoma and induction of apoptosis

目的 探讨分叉双歧杆菌的完整肽聚糖在体内对大肠癌的抑制作用及其抑瘤机制。方法 以大肠癌裸鼠移植瘤为动物模型，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原位观察了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 完整肽聚糖注射组大肠癌移植瘤的生长速度显著慢于对照组，完整肽聚糖的抑瘤率达５１ ．４１ ％ ；此外完整肽聚糖注射组移植瘤组织中可见多量的处于凋亡不同时期的瘤细胞，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（ Ｐ＜０ ．０１），而Ｂｃｌ２ 蛋白的表达情况则相反。结论 分叉双歧杆菌的完整肽聚糖在体内能显著抑制大肠癌的生长。

Objective To explore the inhibition of whole peptidoglycan of bifidobacterium in experimental colorectal carcinoma and its antitumor mechanisms. Methods The growth rate, ultrastructure, density of apoptotic cells and positive expression rate of the Bcl 2 and Bax oncoprotein were investigated in nude mouse transplantation tumors of colorectal carcinoma by electronmicroscopy, in situ end labeling and immunohistochemistry, depending on the animal model of nude mouse transplantation tumors of colorectal carcinoma. Results The growth rate of transplantation tumors of colorectal carcinoma in the whole peptidoglycan injection group was slower than that in the tumor control group. The tumor inhibition rate of whole peptidoglycan was 51.41%. Many apoptotic cells of transplantation tumors in the whole peptidoglycan group were observed. The density of apoptotic cells, expression rate and positive cell density of Bax oncoprotein were significantly higher than those in the whole peptidoglycan injection group when compared with those in the tumor control group ( P < 0.01 ). The expression rate of Bcl 2 oncoprotein was contrary to that of Bax oncoprotein. Conclusion Whole peptidoglycans of bifidobacteria bifidum not only markedly inhibit the growth of colorectal carcinoma in vivo, but also induce apoptosis of colorectal carcinoma.