茶多酚在树肝癌形成中的化学预防作用

目的　探讨茶多酚对黄曲霉素B1(AFB1)和乙型肝炎病毒(HBV)诱发树肝细胞癌作用的影响。方法　成年树分成三组:A组(AFB1+HBV+茶多酚组)、B组(AFB1+HBV组)和C组(空白对照组),实验期间定期抽血检查HBV感染标志和进行剖腹手术取肝组织活检,观察各组肝癌发生率、肝癌出现时间、HBV感染持续时间,并采用免疫组化方法检测肝癌形成过程中p53、bcl- 2、bax、survivin、GSTA1、SOD1、IL -2和SCF等蛋白在各组各时段的表达情况。结果　在实验第90、105、120、135、150、165周各个时段中,A组的肝癌发生率均低于B组;A组首例肝癌出现时间及肝癌平均出现时间均晚于B组;A组HBV感染标志(HBsAg,HBeAg和HBcAb)的平均持续时间短于B组;在诱癌中期(实验第60 周)及肝癌组织内突变型p53、凋亡抑制基因bcl -2和survivin蛋白的表达率均为A组低于B组。但上述差异在统计学上大部分无显著性。结论　茶多酚对黄曲霉毒素B1和HBV诱发树肝癌有一定程度的保护作用;可以促进树体内的HBV感染标志的消除。茶多酚可能是通过促进终致癌物的解毒、抗氧化作用、提高免疫功能、诱导肿瘤细胞凋亡等途径起到预防树肝癌的作用。

Effect of tea polyphenal on chemopreventing hepatocellular carcinoma of tree shrew

Objective To evaluate the effect of tea pol yphenol on preventing hepatocellular carcinoma (HCC) of tree shrew (Tupaia bel angeri chinensis) induced by both aflatoxin B 1 (AFB 1) and human he patitis B virus (HBV). Methods Adult tree shrews were divided into three groups. Grou p A was infected firstly with HBV, then fed with AFB 1 and tea polyphenol. Group B was infected firstly with HBV and then only fed with AFB 1. Group C was as a normal control. Serum collections (for testing HBV markers) and liver biopsies were performed periodically during the experiment. The incidence of HC C, the average time of HCC occurrence and the persistence of HBV infection in ea ch group were observed. Immunohistochemical method was applied for detecting the expression of p53, bcl-2, bax, survivin, GSTA1(glutathione S-transferases al pha 1), SOD1(superoxide dismutase 1),IL-2(interleukin-2)and SCF(stem cel l factor)of the animals in each groups at different time points during the expe riment. Results At the 90th, 105th, 120 th, 135th, 150th and 165th wee k of the experiment, the incidences of HCC in group A were always lower than tho se in group B. Both the first HCC and the average time for HCC occurrence in gro up A were later than those in group B. The average persistent time of carrying H BV infection marker(HBsAg,HBeAg and HBcAb)in group A was shorter than that in g roup B. The expression of mutated p53 protein, apoptosis-inhibitor (bcl-2 and survivin) proteins in group A were lower than those in group B. Most of the dif ferences between the group A and group B had no statistical significance however . Conclusions Tea polyphenol has the protective effect on hepatoc arcinogenesis of tree shrew induced by HBV and AFB1. It might have the ability t o clean the HBV infection markers as well. The mechanism for tea polyphenol prev enting HCC might be relate to its ability of promoting carcinogen-detoxificatio n, inducing antioxidation-activity, improving immune function and inducing apop tosis of neoplastic cells.