RESUMO
Background: Recent reports indicated the involvement of microRNAs (miRNAs) deregulation in colorectal adenomatous mucosa and different stages of colorectal cancer (CRC). Aims: The purpose of this study was to analyze a panel of miRNAs previously selected by bioinformatics analysis from SAGE human colorectal cancer library compared to normal colorectal library in order to identify microRNA species with altered expression in colorectal cancer. Methods: We analyzed the expression of let-7a, miR-21, miR-15a, miR-141, miR-143, miR-145 and miR-150 in 15 tumor tissues from patients who undergone surgery for CRC and 4 non-tumor adjacent tissues. The expression of miRNAs was measured by real-time PCR. Relative quantification of miRNA expression was calculated using the 2(-Delta Delta C(T)) method. Results: Our findings showed under expression of miR-143, miR-150 and miR-145 in about 6-fold (p = 0.05), 5-fold and 4-fold (p = 0.01), respectively, in CRC compared to normal colorectal tissue. In addition, there was no association between each miRNA expression and tumor stage or tumor localization. Conclusion: Our results support that under expression of miR-143, miR-150 and miR-145 might be involved in colorectal carcinogenesis. However, the lack of knowledge about miRNA target genes postpones full understanding of the biological functions of downregulated miRNAs in CRC.