Mechanism of Regulatory Effect of MicroRNA-206 on Connexin 43 in Distant Metastasis of Breast Cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>MicroRNA-206 (miR-206) and connexin 43 (Cx43) are related with the distant metastasis of breast cancer. It remains unclear whether the regulatory effect of miR-206 on Cx43 is involved in metastasis of breast cancer.</p><p><b>METHODS</b>Using quantitative real-time polymerase chain reaction and Western blot, the expressions of miR-206 and Cx43 were determined in breast cancer tissues, hepatic and pulmonary metastasis (PM), and cell lines (MCF-10A, MCF-7, and MDA-MB-231). MCF-7/MDA-M-231 cells were transfected with lentivirus-shRNA vectors to enhance/inhibit miR-206, and then Cx43 expression was observed. Cell counting kit-8 assay and Transwell method were used to detect their changes in proliferation, migration, and invasion activity. The mutant plasmids of Cx43-3' untranslated region (3'UTR) at position 478-484 and position 1609-1615 were constructed. Luciferase reporter assay was performed to observe the effects of miR-206 on luciferase expression of different mutant plasmids and to confirm the potential binding sites of Cx43.</p><p><b>RESULTS</b>Cx43 protein expression in hepatic and PM was significantly higher than that in the primary tumor, while no significant difference was showed in messenger RNA (mRNA) expression. MiR-206 mRNA expression in hepatic and PM was significantly lower than that in the primary tumor. Cx43 mRNA and protein levels, as well as cell proliferation, migration, and invasion capabilities, were all significantly improved in MDA-MB-231 cells after reducing miR-206 expression but decreased in MCF-7 cells after elevating miR-206 expression, which demonstrated a significantly negative correlation between miR-206 and Cx43 expression (P = 0.03). MiR-206 can drastically decrease Cx43 expression of MCF-7 cells but exerts no effects on Cx43 expression in 293 cells transfected with the Cx43 coding region but the lack of Cx43-3'UTR, suggesting that Cx43-3'UTR may be the key in Cx43 regulated by miR-206. Luciferase expression showed that the inhibition efficiency was reduced by 46.80% in position 478-484 mutant, 16.72% in position 1609-1615 mutant; the inhibition was totally disappeared in double mutant (P = 0.02).</p><p><b>CONCLUSIONS</b>MiR-206 can regulate the expression of Cx43, the cytobiological activity, and the metastasis of breast cancer through binding to the two binding sites in Cx43-3'UTR: position 478-484 and position 1609-1615.</p>

Expression of breast cancer resistance protein and p-glycoprotein in residual breast cancer tissue after chemotherapy and its correlation with cancer stem cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To compare the expression differences of breast cancer resistance protein(BCRP/ABCG2) and P-glycoprotein(P-gp) in breast cancer tissue before chemotherapy and in residual breast cancer tissue, and to explore its correlation with breast cancer stem cells.</p><p><b>METHODS</b>Immunohistochemistry was used to detect the expression of ABCG2, P-gp, and breast cancer stem cells(BCSCs) markers(CD44 and CD24) in breast cancer tissue before chemotherapy and residual breast cancer tissue after chemotherapy. Immunofluorescence was applied for determination of the CD44 and CD24 protein expressions of BCSCs microspheres cells. The monoclone-forming ability of BCSCs microspheres cells was detected by limited dilution assay. The expressions of ABCG2, P-gp, CD44, and CD24 proteins were detected by Western blot.</p><p><b>RESULTS</b>Compared with those in breast cancer tissue before chemotherapy, the expression levels of ABCG2 and P-gp were positively correlated with the expression level of CD44 protein(Χ(2)=41.34, r=0.83;Χ(2)=22.81, r=0.61) in residual breast cancer tissue after chemotherapy;meanwhile, they were negatively correlated with the expression of CD24 protein(Χ(2)=-21.25, r=0.72;Χ(2)=-17.26, r=0.65) (all P<0.05) .The diameter of BCSCs microspheres were increased significantly after chemotherapy.The content of BCSCs increased by about 2.5 times after chemotherapy.The expressions of ABCG2, P-gp and CD44 proteins significantly increased and that of CD24 protein significantly declined(P<0.05) .</p><p><b>CONCLUSION</b>Chemotherapy endows residual breast cancer tissue with cancer stem cells-like features, leading to multidrug resistance of breast cancer.</p>

G-protein Coupled Estrogen Receptor 1 Expression in Primary Breast Cancers and Its Correlation with Clinicopathological Variables / 한국유방암학회지

PURPOSE: G-protein coupled estrogen receptor 1 (GPER) probably play important roles in the progression of breast cancer including endocrine therapeutic resistance. We evaluated GPER in primary breast cancers. METHODS: Immunohistochemistry was used to detect GPER in paraffin-embedded tissues of primary breast cancers from 423 patients and GPER expression was correlated with clinicopathological factors. RESULTS: GPER was expressed in 63.8% of specimens, coexpressed with estrogen receptor alpha (ERalpha) in 36.6% of tumors and was positive in 62.5% of the ERalpha-negative tumors. The expression of GPER had no relationship with the status of ERalpha, progesterone receptor and HER2. Although the expression of GPER was significantly inversely related with nodal status (p=0.045), no correlation between GPER expression and other clinicopathological variables (age, menstruation status, tumor size, stage, histologic grade, Nottingham Prognostic Index or pathological type) was found. CONCLUSION: GPER and ERalpha exhibited independent expression pattern of distribution in primary breast cancers. A long-term follow-up and a more definite molecular phenotype for ER are necessary in confirming studies.