Express Of MCM5 In Colorectal Cancer And Diagnosis Of Colorectal Cancer By Detection Of Detection Of MCM5 In Stool

PURPOSE MCM(minichromosome maintenance) protein is essential for eukaryotic DNA replication and is only expressed in proliferating cells. Recent studies have demonstrated the potential use of MCM proteins as markers of proliferation. The aim of this study was to determine the pattern and frequency of MCM5 expression in colorectal normal mucosa, adenoma and cancer, and assess the relationship of MCM5 expression to clinicopathological characteristics of colorectal cancer.METHODS We examined the immunohistochemical expression of MCM5 in colorectal normal mucosa(n=20), adenoma(n=30) and cancer(n=60), and quantified MCM5 expression by calculating a labeling index(LI). And then ,the pattern and LI of MCM5 expression in normal mucosa, adenoma and cancer were compared, and an analysis of the association between MCM5 expression with traditional clinicopathological characteristics of colorectal carcinoma also was carried out.RESULTS MCM5 expression in normal colorectal mucosa is confined to basal third to half of colonic crypts with no expression in surface colonocytes. The median of MCM5 LI is 41.5% (34%~50%) intotal in normal colorectal mucosa. In colorectal adenoma and cancer, MCM5 expression is seen throughout epithelium, including in surface colonocytes. The median of MCM5 LI in adenoma and carcinoma are 63.0%(39%~85%)^ 84.5% (60%~99%), respectively.The differences between normal mucosa , adenoma and cancer are of statistic significance (P<0.001). The median of MCM5 LI in well, moderately and poorly differentiated colorectal cancer are 66.5% (60%~82%) 83.0%(76% - 90%) 95.5%(87% - 99%),respectively. A significant association is also demonstrated between MCM5 LI and the degree of differentiation (P<0.001). There is a trend toward association between MCM5 staining and patient age (P=0.050), but no association is observed with patient sex (P=0.199), tumor size(P=0. 106} ,and Dukes stage (P= 0.620).CONCLUSION These data support evidence that MCM5 may serve as a reliable proliferation marker in colorectal tissue and according to the pattern and LI of MCM5 express, it is feasible to discriminate between normal tissue and adenoma and cancer . It implys that MCM5 has potential as a diagnostic marker for colorectal neoplasia. In addition, MCM5 LI can predict the degree of differentiation in colorectal cancer, which help to predict the clinical outcome.