抑癌基因PTEN在原发性肝癌中的表达及意义

PTEIS expression and its significance in human primary hepatocellular carcinoma

目的 研究抑癌基因PTEN在原发性肝癌发生过程中的作用及意义。方法 应用免疫组织化学和northern杂交分析60例原发性肝癌及对应癌旁组织中PTEN mRNA及PTEN蛋白表达情况,结合患者的临床病理资料分析PTEN在原发性肝肝癌中的意义。结果 PTEN蛋白明确定位于肝细胞胞浆内。60例HCC的癌组织中,PTEN蛋白阳性率为48.3％(29/60),明显低于癌旁肝组织的阳性率(100％)。PTEN蛋白在肝癌组织内的表达阳性率与肝癌的病理学分级、有无癌栓有关,PTEN蛋白在肝癌组织的Ⅰ～Ⅱ级、Ⅲ级、Ⅳ级的阳性率分别为84.0％、23.8％、21.4％,无癌栓形成组PTEN蛋白表达的阳性率为55.56%,有癌栓形成组PTEN蛋白表达的阳性率为26.7％。Northern杂交显示,PIEN基因在肝癌细胞内存在四个转录子,其大小分别为5.5、4.4、2.4、1.8 kb。患者肝癌组织内PTEN mRNA的表达水平明显低于对应的癌旁肝组织。PTEN 5.5 kb和4.4 kb的转录子表达水平的降低与血清中AFP水平、有无癌栓、有无卫星灶及病理学分级有关;2.4 kb的转录子表达水平降低与患者有无癌栓、有无卫星灶有关;1.8 kb转录子表达水平的降低与临床病理学指标无关。结论 PTEN在肝癌的发生过程中可能起重要作用,其表达水平有可能作为反映肝癌进展和预后的病理学指标。

Objective To explore the significance of PTEN (phosphatase and tensin homolog deleted on chromosome 10) in the development of human primary hepatocellular carcinoma (HCC). Methods PTEN protein expression in cancerous liver tissues and paired para-carcinoma liver tissues from 60 HCC patients was detected by immunohistochemistry and PTEN mRNA expression was analyzed by northern blot. The significance of PTEN in the development of HCC was analyzed by investigating the relationship between the expression levels of PTEN protein and mRNA, and the clinicopathological parameters of HCC patients. Results PTEN protein was immunohistochemically stained in the cytoplasmic region of para-carcinoma liver tissues in all the 60 patients, while only 48.3% (29/60) of the patients were positive for PTEN protein in cancerous liver tissues. The positive rate of PTEN protein in HCC tissues were relative to the histological gading and the presence of tumor thrombus. In grade I^n, III, and IV, the positive rates were 84.0%, 23.8%, and 21.4% respectively, and in the group with tumor thrombus was 26.7%, while in the group without tumor thrombus was 55.6%. Northern blot showed that there existed four PTEN mRNA transcripts with the length of 5.5 kb, 4.4 kb, 2.4 kb, and 1.8 kb respectively. The level of PTEN mRNA expression in HCC tissues was much lower than that in the paired para-carcinoma liver tissues. The low expression level of the 5.5 kb and 4.4 kb transcripts was significantly associated with serum AFP value, presence of tumor thrombus, state of satellite lesion and histological grading. The low expression level of the 2.4 kb transcript in HCC was significantly associated with the presence of tumor thrombus and satellite lesions in HCC patients. However, no evident relationship between the lowered expression level of the 1.8 kb transcript and the clinicopathological parameters of HCC was observed in these 60 patients. Conclusions Down-regulation of PTEN expression may play an important role in the development of HCC and the expression level of PTEN may be a potential adjuvant parameter in forecasting the progres and prognosis of HCC.