Breast Cancer Cell Invasion And Metastasis Of Mirnas Related Research

PART1Altered expression of miRNAs in the breast epithelial cells with different invasive potentialObjective To investigate the differential expression of hsa-miRNAs in the breast epithelial cell lines with different invasive potential. Method We profiled miRNAs expression in four breast epithelial cell lines (HBL100, MCF-7, MDA-MB-468and MDA-MB-231) by miRNA array. We further confirmed the certain results of miRNA array by real-time PCR on the same cohort of breast epithelial cells, as well as clincial breast disease tissue specimens. Results miRNA expression profiles were analyzed according to the cell behavior of invasive potential:for example, Group1contained normal breast epithelial cell HBL100and low-invasive breast cancer MCF-7cells, Group2included high-invasive breast cancer MDA-MB-468and MDA-MB-231cells. Compared with Group1,18miRNAs were differentially expressed in these cancer cell lines by miRNA array analysis including7miRNAs of significantly up-regulated and11miRNAs of significantly down-regulated, including miR-339-5p and miR-340. And real-time PCR assay confirmed that the expression miR-339-5p and miR-340was significantly down-regulated in the highly invasive breast cancer cells compared with low-invasive breast cells. Moreover, Altered expression of miR-339-5p and miR-340was also observed in the clinical breast cancer tissue specimens. Conclusion Altered expression of miRNAs was observed in the breast epithelial cell lines with different invasive capacity and clinical breast cancer tissues, which suggested that miRNAs may be involved in the regulation of breast cancer cell invasion. PART2Roles of miR-339-5p and miR-340in breast cancer invasion and migrationObjective To investigate the roles of miR-339-5p and miR-340in breast cancer invasion and migration and their clinical impact among the expression in archival breast tissue specimens. Method We focused on their roles of miR-339-5p and miR-340in regulation of tumor cell growth, migration, and invasion by transient miRNA transfection. And the clinical impact of miR-339-5p and miR-340was analyzed by in situ hybridization on archival breast cancer and benign dieases tissue specimens. Results Induction of miR-339-5p or miR-340expression was able to suppress high invasive MDA-MB-231cells migration and invasion, whereas knockdown of miR-339-5p or miR-340expression induced low invasive MCF-7cell migration and invasion. However, both miRNAs have no significant impact on breast cancer proliferation. In ex vivo, altered expression of miR-339-5p and miR-340was observed in archival breast cancer specimens, compare with benign breast disease specimens. And loss of miR-339-5p and miR-340expression was each associated with lymph node metastasis, high clinical stage, and poor survival of breast cancer patiens. Conclusion miR-339-5p and miR-340may play important roles in breast cancer progression, suggesting that miR-339-5p and miR-340should be further evaluated as novel biomarkers for breast cancer metastasis and prognosis, and potentially therapeutic targets. PART3Mechnism of miR-339-5p and miR-340suppress breast cancer invasion and migrationObjective To investigate the mechanism of miR-339-5p and miR-340in breast cancer invasion and migration. Method The potential target genes of miR-339-5p and miR-340were predicted by bioinformatics tool, and further determined the potential target genes based on their roles in cell invasion and migration, respectively. Experimental determination was performed by using transfection technique. The3’ UTR region of potential target gene was cloned into the psiCHECK-2vector which containing luciferase reporter gene, and then co-transfected with miR-339-5p or miR-340mimics into breast cancer cells. Finally the target genes of miR-339-5p and miR-340were validated by Luciferase Reporter Assay. Results We focused on BCL-6and c-Met, from tens of potential target genes of miR-339-5p and miR-340, for their roles in breast cancer cell invasion and migration. The expression of BCL-6and c-Met was altered by miR-339-5p and miR-340transfection respectively. The luciferase reporter assay revealed that miR-339-5p and miR-340was directly bound to3’UTR of BCL-6and c-Met respectively. Conclusion miR-339-5p and miR-340inhibit breast cancer cells invasion and migration by target oncogene BCL-6and c-Met.