Effect Of MiRNA-362-5p On Malignant Biological Behavior In Breast Cancer Cells

Breast cancer is one of the most common malignancies in women.Accordingtoepidemiological data, breast cancer ranked second in theUnited States, the incidence and the mortality rate has been among thecancer-related mortality. In China, althoughthe incidence of breastcancer is lower in some large or medium-sized cities, but its incidencehas shown an ascending trend. Tothisday, it is generally believed thatthe nosogenesis of breast cancerrelate toa variety of factors, such asgenetic factors, endocrine factors,and so on. Although therearemanytreatment methodsfor breast cancer, but it isapt to recurrence andmetastasis, so it is very important to make an intensive study of breastcancer.Single-stranded RNA which consisted of19to25nucleotides is calledmiRNA.(microRNA, miRNA, miR). This kind of RNA is an important regulatorymolecule to regulate the expression of other functional genes, and playsan important role in the growth and development of biological process,its expression has tissue and time specificity.miRNAregulates geneexpression at the post-transcriptional level mainly through the targetgene3’untranslated region (UTR) totally complementary or partiallycomplementary binding so that the the target genes degradation ortranslational repression. Studies have shown that a variety of microRNAinvolved in the malignant transformation process, such as malignant proliferation, metastasis and recurrence of inhibitor of apoptosis. Somestudies have reported that using microRNA inhibitors reduce miRNA-21highexpression in breast cancer cells, inhibit breast cancer cellproliferation, migration and tumor growth. This discovery provided a newdirection for the breast cancer gene therapy. The experiment focuses onthe impact of a new miRNA-362-5p breast cancer malignant behavior, as wellas related mechanisms of action.In this experiment, we first detected difference of miRNA-362-5pexpression between MCF-7cells, MB231and CCD-1095SK cells, and then wefound that miRNA-362-5p showed high expression in breast cancer cells.In order to investigate whether the high expression of miRNA-362-5pcould affect the biological behavior of breast cancer, we usedmiRNA-362-5p inhibitor to transfect MCF-7cells, MTT’s resuLts showedthat Cell proliferation was significantly inhibited when miRNA-362-5p inMCF-7cells expression was inhibited. Furthermore, we discoveredtransfected MCF-7cells are limited in the G0phase to S phase processby flow cytometry, and the G2/M phase was unaffected. Subsequently, wedetected cell migration through scratches experimental and Transwell,cell migration resuLts showed that the experimental group wassignificantly inhibited. Detecting invasion ability by Transwell methodsimilarly showed that the invasive ability of the cells of theexperimental group was inhibited. To further validate the effect ofmiRNA-362-5p on colony ability of tumor cells, the resuLts ofcolony-forming assay and soft agar cloning assay show that colony abilityof tumor cells decreased, cell adhesion experimental resuLts show thatthe cell adhesion ability of the experimental group also suppressed. Hasbeen reported that, miRNA can affect tumor cells apoptosis, so we usedto cisplatin-induced apoptosis by flow cytometry to detect its impact on the ability of breast cancer cells, the resuLts showed that theexperimental group withered The number of apoptotic cells wassignificantly higher than that of the control group, these experimentalresuLts show that miRNA-362-5p expression may promote the proliferation,migration and invasion of breast cancer cells, while inhibition ofapoptosis occurred.It is discoveredin our previous study thatmiRNA-362-5p promote activation of NF-κB signaling pathway by targetingCYLD so as to promote the proliferation and invasion of leukemia cells,in order to validate whether the miRNA-362-5p of breast cancerplay thesame role through this pathway, we use miRNA-362-5p inhibitors and mimicsto transfect MCF-7cells and CCD-1095SK cells, then detectCYLD expressionand NF-κB signaling pathway activation through western blot, resuLtsshow when the miRNA-362-5p is inhibited the expression of CYLD is restoredbutthenuclear NF-κB descended in MCF-7cells, when the miRNA-362-5pexpression is restored, the expression of CYLD descended andthe nuclearNF-κB is raised, thus in breast cancer cells, miRNA-362-5p promotes NF-κB signaling pathway activationby inhibiting the CYLD expression. Allin all, our experimental resuLts show thathigh-expressionofmiRNA-362-5pin MCF-7cells promotes cell proliferation, migration andinvasion, inhibitsapoptosis, and those effects may be related to theinhibition of CYLD expression thereby contributing to the activation ofNF-κB signaling pathway.