甲基苄基亚硝胺诱导大鼠食管癌癌前病变食管组织中β-catenin表达及其Ser675位点磷酸化水平的变化

Effects of methyl benzyl nitrosamine on β-catenin and p-β-catenin(Ser675) in esophageal precancerous lesions in Wistar rats

目的:探讨甲基苄基亚硝胺(MBNA)诱导食管癌前病变食管组织中-连环蛋白(-catenin)mRNA转录、蛋白表达及其Ser675位点磷酸化水平的变化。方法:Wistar大鼠按3.5 mg/kg皮下注射0.15%MBNA溶液,每周2次作为模型组,以同批次正常大鼠(皮下注射生理盐水)为对照组,每组8只,连续10周,于造模第10周处死2组大鼠,观察食管黏膜病理变化,采用定量PCR检测食管组织中β-catenin mRNA转录水平,Western blot检测β-catenin蛋白及其Ser675位点磷酸化蛋白表达水平,免疫组化检测β-catenin蛋白表达的定位情况。结果:MBNA诱导10周后模型组大鼠均可见食管黏膜粗糙,部分可见乳突瘤,食管黏膜病理学检查呈轻度不典型增生,且模型组大鼠食管组织中β-catenin mRNA转录水平(0.619±0.086)较正常组(1.000±0.235)降低(P<0.01);β-catenin蛋白表达水平(1.476±0.363)较正常组(1.000±0.496)升高(P<0.05);Ser675位点磷酸化β-catenin蛋白表达水平(2.150±0.469)较正常组(1.000±0.367)升高(P<0.01);免疫组化结果显示β-catenin定位表达于食管黏膜上皮细胞,且模型组中的表达较正常组增强。结论:β-catenin蛋白的异常表达及其Ser675位点磷酸化水平的升高与食管癌变的病理变化可能直接相关,可作为食管癌研究的靶点。

OBJECTIVE： To find the changes ofβ-catenin and phosphorylatedβ-catenin （p-β-catenin） Ser675 in esophageal precancerous lesions in Wistar rats induced by methyl benzyl nitrosamine （MBNA）.METHODS： Wistar rats received MBNA injections at dose of 3.5 mg/kg 2 times per week. At 10 weeks,the pathological changes of esophageal mucosa were examined.β-catenin mRNA level was measured by quantitative real-time PCR and the expressions ofβ-catenin protein and p-β-catenin（Ser675） were evaluated by Western blot. The location ofβ-catenin was detected by immunohistochemistry.RESULTS：Compared with normal group,the level ofβ-catenin mRNA was significantly decreased,the levels ofβ-catenin and p-β-catenin （Ser675） protein were significantly increased in treated group.CONCLUSION：The elevated protein levels ofβ-catenin and p-β-catenin （Ser675） were related with esophageal precancerous lesions in Wistar rats induced by MBNA ,and could be considered as an indicator of esophageal carcinoma.