胃癌组织中EphA2基因的表达及其与细胞凋亡、增殖的关系

目的 探讨EphA2基因在胃癌组织中表达的生物学意义及与细胞凋亡、增殖的关系.方法 利用免疫组织化学法(immunohisochemistory,IHC)检测82例胃癌手术切除标本的癌组织、癌旁组织及正常胃黏膜中EphA2的表达,采用逆转录聚合酶链反应(RT-PCR)及Western印迹技术对其中随机选取的30例标本进行EphA2 mRNA及其蛋白的定量检测,分析其表达与临床病理参数的关系.采用流式细胞术(FCM)检测82例癌组织中细胞凋亡率及增殖指数(PI),分析EphA2表达与细胞凋亡、增殖的关系.结果 IHC结果显示EphA2在癌组织中的表达显著高于癌旁组织及正常胃黏膜(P<0.01),且随胃癌分化程度降低、浸润深度增加及淋巴结转移而升高(P<0.05),但与肿瘤大小、患者年龄无关(P>0.05);RT-PCR结果显示EphA2 mRNA在各组中的表达水平无显著性差异(P>0.05);Western印迹与IHC结果一致,显示EphA2蛋白在癌组织中异常高表达(P<0.01).FCM结果显示EphA2高表达组细胞凋亡率显著低于低表达组(P=0.018),而其PI显著高于低表达组(P=0.002).结论 EphA2在胃癌组织中表达明显上调,可抑制细胞凋亡,促进细胞增殖,在胃癌的发生发展中发挥重要作用,其机制与EphA2 mRNA的转录异常无关,而可能是其翻译水平上调或蛋白质稳定性增高所致.

Expression of EphA2 gene in gastric carcinoma and the relation between EphA2 and cell apoptosis and proliferation

Objective To investigate the biological significance of EphA2 expression in human gastric carcinoma and its relationship with cell apoptosis and proliferation. Methods Expressions of EphA2 protein in carcinoma tissues, adjacent tissues and normal gastric mucosa were examined by immunohisochemistory (IHC) in 82 patients with gastric carcinoma and then the expressions of EphA2 mRNA and protein were detected by RT-PCR and Western blot in 30 cases selected randomly. The relationship between expressions of EphA2 mRNA and protein and clinic pathological parameters was analyzed. The apoptotic ratio and proliferation index (PI) were determined by flow cytometry (FCM) in 82 cases of carcinoma tissues. The relationship between EphA2 expression and cell apoptosis and proliferation was analyzed. Results EphA2 expression increased in carcinoma tissues compared with that of adjacent tissues and normal gastric mucosa (P<0.01) by ICH and was related to histological differentiation, depth of infiltration and lymphatic metastasis (P<0.05) but not diameter of tumor and age of patients (P>0.05). The expressions of EphA2 mRNA in each group had no statistical difference (P>0.05) by RT-PCR. Western blot results indicated the abnormal high expression of EphA2 protein in carcinoma tissues (P<0.05) with the similarity in IHC. FCM results indicated the apoptotic ratio of high expression of EphA2 cases was significantly lower than that of low expression ones (P=0.018). But the PI of high expression of EphA2 cases was significantly higher than that of low expression ones (P=0.002). Conclusions Over expression of EphA2 in gastric cancer may inhibit cell apoptosis and promote cell proliferation, and plays an important role in the carcinogenesis and metastasis of gastric carcinoma. Its mechanism may not be related to the level of mRNA, which may result from the up-regulation in translational level or the increased protein stability.