RASSF1A在大肠肿瘤中的表达及意义

Study on RASSF1A expression in colorectal adenocarcinoma

目的研究肿瘤抑制基因RASSF1A（RAS相关区域家族1A）在大肠肿瘤中表达及与肿瘤的病理类型、转移、患者预后的关系，探讨其在大肠癌发生及进展中的作用。方法采用免疫组化（SABC）法对45例大肠癌、33例散发性大肠腺瘤、22例正常肠黏膜中RASSF1A蛋白的表达进行检测。结果正常肠黏膜上皮中90．9％显示阳性或强阳性，大肠癌中11．1％呈强阳性，37．8％呈阳性，37．8％呈弱阳性，13．3％呈阴性，与正常肠黏膜相比，RASSF1A蛋白表达有显著减少。经半定量分析，正常肠黏膜中RASSFIA蛋白表达均呈阳性，积分范围在1～12分，平均8．18分；大肠癌中RASSF1A蛋白表达明显减弱或缺失，积分范围在0～12分，平均4．04分，与正常肠黏膜相比，RASSF1A蛋白的表达有显著减少。大肠癌中RASSF1A蛋白的表达与Dukes分期、淋巴结转移无明显相关。结论RASSF1A蛋白在正常肠黏膜中的表达均呈阳性，而在大肠癌中的表达有显著减少，散发性大肠腺瘤中RASSFIA蛋白的表达有所减少，提示RASSF1A功能的缺失促进了大肠癌的发生发展，在腺瘤～癌序列中RASSF1A基因启动子甲基化出现了一个渐进积累、由量变到质变的过程。大肠癌中RASSF1A蛋白的表达与Dukes分期、淋巴结转移无明显相关。

Objective To investigate the function of the RASSF1A tumor suppressor （Ras association domain family 1 isoform A） in human colorectal carcinogenesis. Methods RASSFIA expression was studied by immunohistochemistry in 45 cases of coloreetal adenocarcinomas, 33 cases of colorectal adenomas and 22 cases of normal colon mucosa. Results RASSFIA was decreased in colorectal adenocarcinomas compared with normal colon mucosa. RASSF1A was significantly more abundant in normal colon mucosa compared with colorectal adenocarcinomas （P 〈 0. 005）, while RASSFIA was little decreased in eolorectal adenomas compared with normal tissues （P〉0.05）. Conclusion The decreased RASSFIA occurs early during colorectal carcinogenesis, which contributes to tumour formation, development and angiogenesis. These results suggest that RASSF1A play a role in tumour development at the stage of adenoma formation.