Relationship between differentiation and DNA binding inhibition factor gene1 expression and cell proliferation, vascular endothelial growth factor secretion in MCF-7 breast cancer cell line

Objective To study the influences of differentiation and DNA binding inhibition factor gene1 ( Id1 ) gene expression on cell proliferation and vascular endothelial growth factor (VEGF) secretion in MCF-7 breast cancer cell line.Methods Positive or negative Id1 eukaryotic expression vector (Id1-pcDNA3.1 +/Hygro,Id1-pcDNA3.1-/Hygro),as well as empty vector (pcDNA3.1/Hygro),was transfected into the MCF-7 cells,respectively.Hygromycin was used to select stabilized transfected cell lines.Reverse transcription-polymerase chain reaction (RT-PCR) and cell immunocytochemical staining were performed to detect the expression of Id1 mRNA,Id1 and VEGF proteins.Cell proliferation activity was analyzed by using cell counting,methyl thiazol tetrazolium (MTT) assay and flow cytometry (FCM).The concentration of VEGF in the supernatant from cell cultures was tested by using enzyme-linked immunosorbent assays ( ELISA ).Results In MCF-7 cells transfected with positive Id1 eukaryotic expression vector ( Id1 -pcDNA3.1 +/Hygro),the Id1 expression was up-regulated.Significantly higher cell proliferating activity was found in Id1-pcDNA3.1 +/Hygro group than in the empty vector transfected group (P ＜0.05).Negative Id1 eukaryotic vector (Id1-pcDNA3.1-/Hygro) transfection inhibited the Id1 expression and proliferating activity ( P ＜ 0.05 ).FCM revealed that the proportion of proliferating cells ( S + G2 + M )was (48.45 ± 2.97 ) ％ in the positive Id1 transfected group,( 32.40 ± 0.49 ) ％ in the empty vector trans-fected group,and (23.08 ± 1.56)％ in the negative Id1 transfected group.There were significant differences among these three groups ( P ＜0.01 ).The apoptotic index in the positive Id1 transfected group,the empty vector transfected group,and the negative Id1 transfected group was (3.26 ± 1.28)％,(7.42 ±1.04 ) ％ and ( 11.83 ± 1.59 ) ％,respectively ( P ＜ 0.01 ).Compared to that in the empty vector trans-fected group,the concentrations of VEGF were increased in the positive Id1 transfected group (P ＜0.01 ),and decreased in the negative Id1 transfected group (P ＜ 0.05 ).Conclusion We demonstrated that the proliferation and VEGF secretion of MCF-7 cells were closely correlated with the Id1 gene expression. Key words: Breast carcinoma; Gene expression; . Cell proliferation ; Vascular endothelial growth factor