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Aim To investigate the specific binding sites that histone deacetylases 1(HDAC1) and estrogen receptor α(ERα)can be recruited to regulate the transcriptional activity of p21WAF1/CIP1 promoter in the breast cancer MCF-7 cells, and to clarify the molecular mechanism of suberoylanilide hydroxamic acid(SAHA) and leptin regulating p21WAF1/CIP1 promoter function.Methods The breast cancer MCF-7 cells in logarithmic growth phase were starved with FBS free medium for 24 hours, and treated with 20 μmol·L-1 SAHA(SAHA group) or 0.625 nmol·L-1 leptin(Leptin group) for 24 hours.The cells that were cultured in complete RPMI 1640 medium without any treatment were assigned as control group(Basal group).The cell lysis was prepared and incubated respectively with anti-HDAC1 and anti-ERα antibody by chromatin-immunoprecipitation(ChIP) method overnight at 4℃.The DNA-ChIP was followed the manufacturer′s protocol for the assay.DNA fragments binding anti-HDAC1 and anti-ERα antibody were gathered and purified.The relative expression level of DNA fragments from TSS to the upstream of the p21WAF1/CIP1 promoter region(+2~-4 000 bp) binding with antibody was detected by real-time PCR and analyzed by 2-△△CT method.Results In basal group, HDAC1 and ERα had high affinity with the f1 and f8 fragments of p21WAF1/CIP1 promoter compared to the f4 fragment.In SAHA group, the binding ability of HDAC1 and ERα to the f1 and f8 fragments of p21WAF1/CIP1 promoter was significantly lower than that of the control, while reversing to reach the peak after leptin treatment.Conclusions HDAC1 and ERα can be recruited to p21WAF1/CIP1 promoter by the cell proliferation signal during the proliferation of breast cancer MCF-7 cells.The DNA f1(from 0 to-400 bp) and f8(from-2 800 to-3 200 bp) fragment in the upstream of p21WAF1/CIP1 promoter are the target functional region for the binding with HDAC1and ERα.
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Objective To investigate the specific sites that estrogen receptor (ER)α could be recruited to in the p21WAF1/CIP1 promoter region to regulate its transcriptional activity in MCF-7 cells,and to clarify the molecular mechanism of suberoylanilide hydroxamic acid (SAHA) and leptin in the regulation of p21WAFI/CIP1 promoter function.Methods MCF-7 cells were starved by culturing them in fetal calf serum-free medium for 24 hours,and then treated with 20 μmol/L of 0.88 μL SAHA (SAHA group) or 0.625 nmol/L of 10 μL leptin (leptin group) for 24 hours,or cultured in complete RPMI-1640 medium (control group).Cell lysates were incubated with anti-ERα antibody for ChIP analysis.The relative expression levels of DNA fragments,ranging from the TSS to upstream of the p21WAF1/CIP1 promoter region (+2 to-4 000 bp),that bound the antibody were detected by real-time PCR.Results In the control group,the relative expression levels of f1,f2,and f8 DNA fragments that bound the antiERα antibody were two-fold higher than the relative expression of the f9 fragment (P ＜ 0.01).In the SAHA and leptin groups,the relative expression of f1 to f10 DNA fragment that bound anti-ERα antibody was significantly lower than that of the control.The binding affinity of ERα for the f8 fragment was the lowest (P ＜ 0.01) in the SAHA group,and it was significantly lower than that in the leptin group (P ＜ 0.01).Conclusion ERα could be recruited to the p21WAFI/CIP1 promoter via signaling pathways activated during the proliferation of breast cancer MCF-7 cells.Moreover,the DNA fragment ranging from-2 800 to-3 200 bp upstream of the p21 WAF1/CIP1 promoter is the target functional region for high-affinity binding with ERα.
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To clarify the molecular mechanism of SAHA in the cell proliferation of ER-positive breast cancer cell line MCF-7 induced by leptin. Methods Human breast cancer cell MCF-7 was incubated with SAHA and/or leptin, and cell viability, apoptosis and cell cy-cle of MCF-7 cells were detected by Muse Cell Analy-zer. The expression of proteins related with apoptosis was determined by apotosis antibody array. Results Real-time cell proliferation assays indicated that the in-duction effect of leptin for MCF-7 cells reached the peak at a concentration of 0. 625 nmol · L-1 . SAHA reduced the viability of MCF-7 cells, induced G0/G1 phase arrest in the cell cycle, and triggered the apopto-sis. Meanwhile, SAHA significantly induced the pro-tein expressions of some apoptotic factors, including Bax, Caspase-3, TRAIL DR5, p21CIP1, and inhibited the expressions of Claspin, Clusterin, x-linked inhibi-tor of apoptosis protein(XIAP) and survivin. Howev-er, leptin had reverse effects on the related expression of the proteins. Conclusion The effects of cell prolif-eration by leptin and SAHA treatment in breast cancer ER positive cell line MCF-7 may involve in the activa-tion of apoptosis pathway, in particular with releasing of Caspase-3 trigged by endogenous mitochondrial ap-optosis pathway.
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Objective To explore the inhibitory effect of decorin(DCN) on rat mesangial cell (MsC) growth and on the expression of mitogen-activated protein kinases (MAPKs) and p21 protein. Methods Lipofectin-mediated method was used to transfect DCN vector into MsC. After the screen and identification of transfected MsC, DCN-containing supernatant was collected and added into the culture medium of normal MsC, then flow cytometer was used to detect the cell cycle. Western blot analysis was used to explore the changes of MAPK and p21 protein. Immunofluorescence was adapted to detect the expression of p21 on cultured MsC. Results Compared with normal MsC, the number of G2-M cells treated with DCN-containing supernatant decreased to 35%(P
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Objective To explore whether the antagonistic effect of decorin (DCN)on progression of glomeruloselerosis is associated with the inhibition of the expression of type I and type II transforming growth factor-? receptors (TGF-?R I and TGF-?R II )in mesangial cells (MsC). Methods RT-RCR and Western blot analysis were used to detect the expression of TGF-?R I and TGF-?R II mRNA and their proteins on cultured rat MsC stimulated by exogenous TGF-?1. Lipofectin-mediated method was used to transfect DCN vector into MsC. After screening and identifying of transfected MsC, RT-PCR and Western blot analysis were adapted to detect the changes of TGF-?R I and TGF-?R II expression respectively. Results The expression of TGF-?R I and TGF-?R II mRNA and their proteins on normal MsC stimulated by exogenous TGF-?1 increased in time-dependent manner and reached the peak at 24th hour. Compared with normal and untransfected MsC (1P-1), the mRNA and protein expression of TGF-?R I and TGF-?R II on MsC (3D-5, 7D-1) transfecled by DCN gene decreased significantly, and DCN gene transfection could antagonize the increase of mRNA and protein expression of both receptors caused by exogenous TGF-?1. Conclusions The expression of both TGF-?R I and TGF-?R II decreases obviously in MsC overexpressing DCN gene, which may be one of the importan antagonistic mechanisms of decorin involved in the development of glomeruloselerosis mediated by TGF-?.