硒在防治大肠癌中作用的研究

A study on effect of selenium in prevention and treatment for colorectal cancer

目的：阐明硒在大肠癌发生中的地位及其防治大肠癌的作用机理。方法：包括实验和临床两部分。120只Wistar大鼠以二甲肼（DMH）诱发大肠癌，动物随机分为8组予以不同饮食，处死后尸解，观察各脏器出现肿瘤情况。44例大肠癌患者随机分为治疗组与对照组，观察投药前后血清硒浓度与T淋巴细胞亚群、NK、LAK细胞活性的变化，同时测定35例大肠癌组织和正常大肠组织内硒含量。结果：高脂饮食对DMH的致癌性具有明显的促进作用。硒和钙则有明显阻抑DMH的致癌作用，而且硒对高脂饮食的促癌性也有明显的阻抑作用，锗则未见对DMH的致癌性有任何作用。大肠癌患者血硒水平低于正常值，补硒后血硒明显升高，与对照组差别显著（P＜0．01），治疗组的CD3、CD4、CD4／CD8及NK、LAK细胞活性补硒后有明显升高，与对照组差别显著。此外，大肠癌组织内硒含量明显低于周围大肠组织的硒含量。结论：硒具有阻抑实验性大肠癌发生的作用，补硒具有促进人体细胞免疫的功能，大肠癌的发生则可能与局部低硒以致免疫力降低有关。

Objective: To elucidate the role of selenium (Se) in the pathogenesis of colorectal cancer (CRC) and its mechanism in prevention and treatment for CRC. Methods: DMH induced colon cancer in 120Wistar rats were used. Rats were divided into 8 groups based on different diets. They were killed and autopsied 4 weeks after the last injection of DMH. 44 patients with CRC were randomly divided into therapeutic and control group. The level of serum Se, T lymphocyte subsets NK and LAK cell activity were measured preoperatively and postoperatively. Simultaneously Se content in tumor and normal tissue of the colon were measured in 35 cases. Results: In experimental animals, high fat diet has a significant effect on DMH induced colon cancer. Selenium and calcium can inhibit the effect of DMH and decrease the incidence of colon cancer.Selenium can also interfere the effect of high fat diet but germanium has no effect on colon carcinogenesis.Clinically serum Se level was lowered in patients with CRC and increased sighificantly after Se supplementation in the therapeutic group, P< 0. 01. It was different significantly from that of the control group, P< 0. 01.CD3, CD4, CD4/CD8, NK and LAK cell activity were obviously increased postoperatively in the therapeutic group and significantly different from those of the control group. Se level in tumor was significantly lower than that in normal mucosa in case of CRC (P< 0. 01 ). Conclusions: Selenium can effectively interfere carcinogenesis induced by DMH in colon, In clinics, supplement of Se does effectively increase the immunity of patients with CTC.The carcinogenesis of CRC may be correlated with low level of Se and decrease of immunity in local tissues.