微型染色体维持蛋白2在大肠肿瘤中的表达及其意义

Expression of Mcm2 protein in colorectal neoplasm

目的:研究微型染色体维持蛋白(minichromosome maintenance proteins,MCMs)家族中的一成员Mcm2蛋白在大肠肿瘤中的表达情况及其意义.方法:采用免疫组化染色的方法,检测了23例正常大肠黏膜、33例大肠腺瘤及69例大肠癌组织中Mcm2蛋白的表达,并以标记指数(labelling index,LI)量化其表达.结果:在正常大肠黏膜组织中,Mcm2蛋白表达仅局限于腺体基底部的1/3～1/2部分的增生细胞,而在大肠腺瘤组织和癌组织中,Mcm2蛋白在整个上皮包括肠腔表面的细胞也有大量表达,三者LI的中位数(范围)分别为18%(5%～37%)、35%(15%～75%)、66%(41%～90%),三者之间差异有显著性(P＜0.05).Mcm2蛋白表达在大肠癌患者的不同年龄段(≤40岁和>40岁)、性别、肿块大小(≤3 cm 和>3 cm)、病理学类型、Dukes分期之间无显著性差异(P>0.05),但在大肠肿瘤的不同分化程度(大肠癌的Ⅰ、Ⅱ、Ⅲ级,大肠腺瘤的轻、中、重度不典型增生)之间有显著性差异(P<0.05),呈逐渐升高趋势.结论:Mcm2蛋白是大肠肿瘤组织的一种可靠标志物, Mcm2的表达可以提示大肠癌的恶性程度高低和腺瘤的恶变可能性,有助于临床判断患者的预后以及选择合适的治疗方法.

Objective:To determine the expression of Mcm2(a member of MCMs family) in colorectal neoplasm and to assess the relationship between Mcm2 expression and clinicopathological characteristics of colorectal neoplasm.Methods: Immunohistochemical staining was used to detect the expression of Mcm2 in normal colorectal mucosa(n=23),adenoma(n=33),and cancer(n=69) tissues,and the results were quantified by calculating the labelling index(LI).Results: Mcm2 expression in normal colorectal mucosa was confined to the 1/3-1/2 of colonic crypts basal;there was no expression in coloncytes surface.In colorectal adenoma and cancer,Mcm2 expression was seen throughout epithelium,including the coloncytes surface.The median(range) LI of Mcm2 in these 3 tissues were 18%(5%-37%),35%(15%-75%),66%(41%-90%),respectively.The differences between normal mucosa,adenoma and cancer were statistically significant(P<0.05).There was no statistical significance between the LI of Mcm2 and some clinicopathological characteristics such as the age,sex,size,histopathology and Dukes stage.A significant association was demonstrated between Mcm2 LI and the grade of colorectal cancer and adenoma.Conclusion: Mcm2 may serve as a reliable and useful diagnostic marker for colorectal neoplasm and can predict the degree of differentiation in colorectal neoplasm,which may help to predict the clinical prognosis of the related patients.