Abstract: Objective To screen and verify differentially altered miRNAs in colorectal adenoma-adenocarcinoma sequence and investigate possible mechanism. Methods To screen altered miRNAs in 15 patients of colorectal adenomas, 3 patients of colorectal early cancer and 3 cases of normal control using Human MicroRNA Array. To verify the results in 18 patients of colorectal adenomas, 9 patients of colorectal early cancer and 5 cases of normal control using real-time PCR. Results Compared with group of adenomas, there are 15 altered miRNAsin group of early cancer；compared with group of normal control，there are 13 altered miRNAs in group of early cancer. Level of miR-204，miR-193b and miR-150 was verified further. Serum miR-150 was significantly lower in patients with adavanced carcinoma than normal control (P<0.05). Serum miR-204 was significantly lower in patients with early cancer or adavanced carcinoma (P<0.05 and P<0.01 respectively). Serum miR-193b was significantly lower in patients with adenomas, early cancer or advanced carcinoma ( P<0.05，P<0.01 and P<0.05 respectively). miR-193b mimic significantly inhibited proliferation of HCT116 cells （P<0.05）and promoted apoptosis (P<0.001). meanwhile inhibiting the expression of K-ras and β-catenin. Conclusions Serum miR-204 and miR-193b may serve as novel biomarkers in early diagnosis of colorectal carcinoma. miR-193b may exert tumor suppressing effect in adenoma-adenocarcinoma sequence.

Key words: micro RNA, miR-193b, miR-204, Colorectal cancer, Colorectal adenoma