Abstract:

Abstract:Objective  To investigate the effects of overexpression of DHRS7 gene and short hairpinRNA(shRNA) recombinant plasmid on cell cycles of the human breast cancer MCF-7 cells and the relationship between DHRS7 and breast cancer invasion,and to clarify the effect of DHRS7 on the development of breast cancer.Methods  The cDNA fragment encoding human DHRS7 was obtained from mRNA of breast cancer cells MCF-7 by RT-PCR.Then it was cloned into vector pcDNA3.1(+) plasmid to conduct DHRS7-shRNA-pGenesil.There  were four groups in the experiment:  pcDNA3.1-DHRS7 group,negative control group(pcDNA3.1 group),blank control group and DHRS7-shRNA-pGenesil group.Then the plasmids were transfected into MCF-7 cells using Fugene HD transfection agent,and the expressions of DHRS7 were determined by RT-PCR and Western blotting.The cell cycles were analyzed by flow cytometry.The expression of DHRS7 protein in carcinoma in stiu and infiltrating carcinoma were detected by immunohistochemical staining.Results The recombinant plasmid pcDNA3.1-DHRS7 was constructed correctly.RT-PCR analysis and Western blotting showed that the expression of DHRS7 protien in pcDNA-DHRS7 group was higher than that in blank control group（P<0.05）,and the expression of DHRS7 protien in DHRS7-shRNA-pGenesil group was lower than that in blank control group（P<0.05）.Flow cytometry showed the overexpression of DHRS7 increased the cells in S phase （P<0.05） and the low expression of DHRS7 increased the cells in G2 period（P<0.05）.Immunohistochemical staining showed that DHRS7 protein expression was higher in the  breast cancer  in situ,and the positive rate was 100%(37/37)；the DHRS7 protein expression  was lower in the breast infiltrating carcinoma tissues,and the positive rate was 18.9% (7/37),there was significant difference between them(P<0.01).Conclusion DHRS7 gene may be involved in the regulation of cell cycle in MCF-7 cells,which can inhibit cell proliferation and the expression missing of DHRS7 protein may promote invasion of  breast cancer.

Key words: DHRS7 gene；overexpression；interference；cell cycle；breast tumor；MCF-7 cells