| Breast cancer is the most common malignancy and a major cause of death amongfemale population. Estrogen receptor expression in breast cancer cells is associated with thetreatment and prognosis.Estrogen binds to and activates estrogen receptor，and then exertsthe effects through a complex array of signaling pathway. Estrogen receptors are membersof the nuclear receptor superfamily, the main points are ERα，ERβ and ERγ. Function ofERα has been cleared studied; ERγ has few research relatively; the structure and functionof ERβ is one of the hot research spot in recent years.ERβ1is considered to be thewild-type、full-length human ERβ, and is the only fully functional isoform receptorcurrently known. ERβ1tends to form heterodimers with other isoforms under thestimulation.In contrast, ERβ2，3，5do not form homodimera and have no innate activities oftheir own.Most studies show that ERβ could play an anti-proliferation effect. ERβ acts as atumor suppressor gene in the malignant tumor. Studies also found that the decreasedexpression of ERβ in various epithelial cancer, such as prostate cancer, breast cancer, lungcancer and ovarion cancer. Accumulated dates from protein studies in cancer tissuesindicate that positive expression of ERβ correlates with a favorable prognosis.However,until now, the mechanisms responsible for the decreased expression of ER β in tumors andthe biological functions of ERβ remain elusive.Epithelial-mesenchymal transition play an important role in the process of epithelialtumor metastasis, in which downregulation of E-cadherin is most important molecular eventduring EMT. Studies have shown that the expression of ERα could upregulate E-cadexpression through lower the slug expression and then reduce the incidence of EMT.Nevertheless, no study on the relationship between ERβ expression and EMT has beenreported.This study focus on the preliminary experimental study on the relationship betweenERβ and EMT. This topic is major on the relationship of ERβ and EMT in breast cancer. By detectingthe target protein expression of the clinical breast cancer specimens and regulating the targetprotein expression in vitro cell experiments, we want to explore the relationship betweenERβ1and E-cad, to reveal what kind of impact of this regulation affect malignant behaviorof cancer cells role of ERβ1expression in EMT, finally to provide a basis for furtherelucidate the mechanism of the biological behavior of ERβ in breast cancer.Research methods and main results：1. ERβ1expression in human breast cancer tissue and its correlation analysiswith E-cadherinMethods: Collection131cases of human breast invasive carcinoma of no special typetissue specimens and their clinical case informations. Using tissue microarray andimmunohistochemical staining methods, ERβ1and E-cadherin protein expression wasdetected in the tissues. Using spss17.0software to analyze the ERβ1expression associatedwith the pathological parameters, and the correlation analysis between ERβ1and E-cadherinexpression.Results: In131cases of human breast invasive carcinoma of no special tissue,numbers of ERβ1expression (-),(+) and (++) is53cases,67cases and11casesrespectively, ERβ1total expression rate is59.5%(78/131). Numbers of E-cad expression(-),(+) and (++)is46cases,44cases and41cases respectively, E-cad total expression ratewas64.9%(85/131). At the same time,47.3%(62/131) of cases co-express ERβ1and E-cad.Using Spearman rank correlation analysis ERβ1and E-cad expression, the correlationcoefficient r=0.456, P <0.000. It turned out that ERβ1and E-cad expression werepositively correlated expressed in human breast invasive carcinoma of no special tissue.ERβ1expression related to histological grade (P＜0.05), the higher histological grade, theless expression of ERβ1.Also ERβ1Expression with age, menopausal status, tumor size,lymph node metastasis, ERα, PR and Her2expression have no significant statisticaldifference.2. Effect of ERβ1gene on E-cadherin expression in human berast cncer cellsMDA-MB-231.Method: Using transient over-expression plasmid and siRNA interference method todeal with human breast cancer cells MDA-MB-231, to get breast cancer cells with high expression and reduced expression ERβ1. Transfected cells were collected after48hourstreatment, divided into four groups, namely control group, negative control group (join onlyliposomes), ERβ1interference group and ERβ1overexpression group. The mRNA andprotein expression levels of ERβ1and E-cadherin were detected through RT-PCR and WBassay, and the gray values for statistical analysis.Results: There is no different of the two indexes expression between the black controlgroup and negative control group (P＞0.05),no matter the gene and the protein level. Butcompared to the control group, the expression of mRNA and protein levels of E-cadherinand ERβ1were lower in ERβ1interference group, indicating an effect of small interferingRNA and the corresponding reduction in the regulation of E-cadherin. ERβ1overexpressiongroup expression ERβ1and E-cadherin at mRNA and protein levels were increased,indicating that high expression plasmid then effective, and the corresponding increase inregulation of E-cadherin. These differences were statistically significant (P <0.05).3. Effect of ERβ1gene on migration and invasion of human berast cncer cellsMDA-MB-231.Method: Using transient over-expression plasmid and siRNA interference method todeal with human breast cancer cells MDA-MB-231, to get breast cancer cells with highexpression and reduced expression ERβ1. Transfected cells were collected48hours aftertreatment, divided into four groups, namely control group, negative control group (join onlyliposomes), ERβ1interference group and ERβ1overexpression group. Using Transwellchamber and BD Matrigel, respectively, after trained, fixed, stained and counted the numberof cells piercing, statistical analysis.Results: Both in migration and invasion experiments, there was no difference (p>0.05)between the transformaed cells number between blank control group and negative controlgroup. But compared to the control group, the transformaed cells number of ERβ1interference group increased both in the migration and invasion experiments, whichdescribed the changed expression of ERβ1and E-cadherin could enhance cell migration andinvasion ability. The transformaed cells number of ERβ1over-expression group decreasedcompared with control group both in the migration and invasion experiments.The resultsdescribed the high-expression of ERβ1and E-cadherin could reduce cell migration andinvasion ability. These differences were statistically significant (P <0.05). Conclusions: In breast cancer specimens, ERβ1expression related to histological grade,the higher histological grade, the less expression of ERβ1. ERβ1was positively correlatedwith E-cadherin expression. Results of cells and functional experiments showed thatintervention ERβ1can influence the expression of E-cadherin and cell migration, invasionability of breast cancer cells. In conclusion, we believe that the ERβ1involved EMTprocess through E-cadherin in breast cancer. |
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