The Role Of Cat25 In Screening Hereditary Nonpolyposis Colorectal Cancer

Objects To study the role of CAT25mononucleotide's repetitive sequence in screening HNPCC in Chinese people and compare its sensitivity with BAT26 in Screening HNPCC.Methods 35 patients in accordance with Bethesda diagnosis standards were screened as study objects and their colorectal tumor and normal intestinal mucosa samples (control) were collected for study. 80 negative people's peripheral blood samples were collected as reference objects. After extracting genome DNA from all tissues and blood samples, we amplified five sites using PCR (BAT26,BAT25,D2S123,D5S346 and D17S250) and detected their mutations in all tissue samples, and meanwhile detected the mutation of CAT25 only in tumor samples. BAT26 and CAT25's detection results of 80 negative people's peripheral blood samples were referred for normal values. Eventually, immunohistochemistry was taken to detect hMSH2 and hMLH1 expression in MSI-H positive tumor samples.Results 9 in 35 tumor samples displayed MSI-H positive. BAT26 and CAT25 were abnormal in these samples, while normal in the 4 MSI-L and 22 MSS negative samples. Allelic sizes of CAT25 and BAT26 centralized in 147-149bp and 116-118bp respectively. Immunohistochemistry negative detection of hMSH2 and hMLH1 were 1 and 3 respectively in the 9 MSI-H positive samples.Conclusion CAT25 is a very useful and sensitive biomarker in screening HNPCC among Chinese people. There is no significant difference in identifying HNPCC between CAT25 and BAT26 in our study. In addition, allelic size distribution of BAT25 is more centralized than BAT26 in Chinese people. It means that it may have higher sensitivity in identifying tumors with MSI-H in big samples study and can further screen HNPCC from MSI-H patients.