| In our country, Breast cancer is a disease with higher morbidity and mortality ofmalignant tumors in woman, the transfer has been the leading cause of death in patients withbreast cancer, which is also one of the difficulties of breast cancer treatments. Gap junctions(GJ) is in between adjacent cell membrane channel structure, connexin(Cx) is the basiccomponent of unit connection protein of GJ, and human breast tissue mainly express Cx26,Cx43; it is found in the study About the mechanism of connection protein43to regulate themalignant tumor metastasis that, Cx43mediated biphasic direct exchange of electric orchemical signals between adjacent cells, metastasis always associated with an increasedexpression of Cx43and intercellular communication disorders in breast cancer. It is found thatthere are a number of transcription factor binding sites on the promoter of Cx43,such astranscription factor SP-1(specificity protein-1), SP-3, AP-1(the activator protein1), c-jun, etc. Various chemical or physical stimuluses play a role in regulating the expression ofCx43gene transcription through these transcription factors. However, regulation oftranscription factor is numerous, relationship between them is complicated, mRNA need to betranslated into protein to be functional, and the function of a molecular reflected in proteinlevel ultimately; Our previous studies have found that the post-transcriptional control of Cx43may be involved in the regulation of the axillary lymph node metastasis of breast cancer, butthe role of post-transcriptional control of Cx43in distant metastasis of breast cancer is stillunclear.MicroRNA (miRNA, miRNA) is the largest class of post-transcriptional controlregulatory factors, Studies of MicroRNAs in breast cancer found that a variety of micrornastake part in the regulation of breast cancer metastasis by targeting multiple genes.In ourprevious study, We use the the human breast cancer primary tumors samples by surgicalremoval and the matching metastasis of axillary lymph node samples as the research object to discover the relationship between miR-206and CX43protein,we found that, Axillary lymphnode metastasis in breast cancer arises miR-206mRNA expression is decreased obviously,and obviously increase the protein expression of Cx43, there is a significant negativecorrelation relationship between miR-206and Cx43. it is suggests miR-206may play animportant role in the axillary lymph node metastasis of breast cancer And Cx43might be itsdownstream molecular. However, whether miR-206regulate the distant metastasis of breastcancer through Cx43and its mechanism is unrevealed. This study intended to using humanbreast cancer cell line MCF-7, and MDA-MB–231, by intervening in the expression ofmiR-206, observe the expression of Cx43and its influence on cell biological characteristics.Research methods and main results：1. research of the relationship between MiR–206and Cx43:Methods1) By choosing the literature reported high expression of Cx43breast cancercell line MCF–7and low expression of Cx43breast cancer cell line MDA–MB–231,confirme the Cx43expression situation in the two cell lines by immunofluorescence method;(2) detect the expression of miR–206of two cell lines by qRT–PCR.Results: expression quantity of miR–206of MCF–7cell was obviously higher thanthat of MDA–MD–231cells, the expression of Cx43in MCF–7cell was obviously lowerthan that in MDA–MB–231cells.2. preliminary research on the influence of biological characteristics in breast cancercells of MiR-206by regulating expression of Cx43and its mechanism.Methods: With qRT-PCR,the miR-206ecpressionglevels of breast cancer cell linesMDA-MB-231and MCF-7cells were detected.The levels of miR-206in MDA-MB-231andMCF-7cells were up-regulated or down regulated by lentiviral vector-mediatedtransfection.Cx43expression was detected by qRT-PCR and Western blotting.Cell migratioyand invasive abilities were measured by Transwell chamber assay. Cell proliferation and cellapoptosis was assessed by CCK-8assay and FCM respectivelyResults:It was found that MCF-7cells showed lower miR-206level but higher Cx43level than MDA-MB-231cells. After shRNA-mediated miR-206up-regulation,MCF-7cellsdisplayed increase of miR-206level, decrease of Cx43mRNA and protein ecpression, andsuppression of cell proliferation, migration and invasion(p<0.05).Moreover,significantincrease of proportion of apoptotic cells were detected in the transfected cells(p<0.05), and the G2cell stage were blocked in the transfected cells(p<0.05).After shRNA-mediatedmiR-206down-regulation, MDA-MB-231cells displayed decrease of miR-206level,increase of Cx43mRNA and protein expression, and enhancement of cell proliferation,migration and invasion(p<0.05).ConclusionsMicroRNA-206may play an tumor-suppressive-like role in the development of breastcancer through down-regulation of Connexin43expression possibly, suppress the ability ofproliferation and promote apoptosis, leading to the decrease of malignancy of breast cancer,which are based on the following evidences:(1)Changing of the expressing level of miR-206will lead the changing of Cx43level,lower miR-206level always associated with higher Cx43level in breast cancer cells.(2)After shRNA-mediated miR-206up-regulation,tumor cells displayed increase ofmiR-206level, decrease of Cx43mRNA and protein ecpression, and suppression of cellproliferation,migration and invasion Moreover, significant increase of proportion of apoptoticcells were detected in the transfected cells and the G2cell stage were blocked in thetransfected cells. |
PDF Full Text Request