Expression Of Hsa-miRNAs In Breast Cancer And Their Significances

Background: MicroRNAs (miRNAs) are a new class of short noncoding regulatory RNAs and they become a research hotspot in recent years. A large body of research shows that miRNAs play fundamental roles in many biological processes, including embryonic development, fat metabolism, cell growth, differentiation and apoptosis, and gene regulation.The expression of miRNAs has been examined in a wide range of breast cancer cell lines, and in clinical normal and cancer breast tissues. Accordingly, altered miRNA expression is likely to contribute to human tumorigenesis.Objective: To investigate the expression of hsa-miRNAs change in breast cancer and its biological significanc.Method: The expression of 42 kinds of miRNAs was detected in 91 cases of breast carcinoma, 26 cases of preicancerous breast tissues and 38 cases of benign breast lesions including 21 cases of fibroadenoma and 17 cases of adenosis on tissue microarray sections by in situ hybridization. Using bioinformatics tools, the possible target genes of miRNA-145 which change significantly in breast cancer were forecasted. The expression of one of the target genes was detected by immunohistochemistry.Results:(1) Compared with preicancerous breast tissues, there were 14 kinds of miRNAs altered significantly (P<0.05), of which 9 miRNAs upregulated, 5 miRNAs downregulated.(2) Compared with benign breast lesions, there were 17 miRNAs altered significantly (P<0.05), of which 8 upregulated, 9 downregulated.(3) There were positive correlations between miR-145 expression and lymph node metastasis (P<0.01), TNM stage (P<0.05) and c-erbB-2 overexpression (P<0.05). (4) No correlations were found between the expression of miR-145 and age, size, histological grading, ER and PR status (P>0.05).(5) There were no correlations between cum survival rate, recurrent survival rate of breast cancer and the high expression of miR-145 breast cancer tissue (P>0.05).(6) Smad3 expression decreased concordantly with miR-145 in breast cancer tissue (P<0.05).Conclusion:(1) The altered expression of miRNAs might play a role in the pathogenesis and progression of breast cancer.(2) MiR-145 may be a useful molecular marker in breast cancer.(3) Smad3 might be evaluated as one of the potential target genes of miR-145.