| Objective:To reveal the role of Id2 in invasion potential in poorly invasive MCF-7 and SKOV-3 cancer cells.Methods:Human breast cancer cell line MCF-7 and ovarian cancer cell line SKOV-3 were transfected with pcDNA3.1-Id2,pcDNA3.1-Id2-DBM and pcDNA3.1-Id2-DBM-δHLH vectors,and cells transfected with blank vector pCDNA3.1 were used as control.Protein levels of Id2 and its mutants and E-cadherin were determined by western blot analysis and mRNA levels of Id2 and its mutants were determined by RT-PCR.The effects of Id2 and its mutants on cell proliferation were determined by[3H]-thymidine incorporation assay and the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide(MTT) dye method.The in vitro invasion potential of cells was evaluated by Transwell assay. Cell motility was assessed by scratch wound assay.Results:Ectopic transfection of the wild-type Id2 markedly increased the protein and mRNA expression of Id2 in MCF-7 and SKOV-3 cells;the protein level but not mRNA level was further increased by transfection with the degradation-resistant Id2 form.The ectopic expression of Id2 or its mutants did not alter proliferation of either MCF-7 or SKOV-3 cells.Transfection of the wild-type Id2 significantly induced the invasion potential and migratory capacity of cells,which was further augmented by transfection with the degradation-resistant full-length or HLH-deleted Id2.In addition,the E-cadherin protein was downregulated after transfection compared to control.It indicated that overexpression of protein Id2 promoted cell migration.This effect might be related with the decrease of E-cadherin,and it still retained after the HLH domain of Id2 was deleted. Conclusions:Overexpression of Id2 in MCF-7 and SKOV-3 cells indeed increases the cells'invasive potential through a novel mechanism independent of dimerization to basic helix-loop-helix factors.E-cadherin contributes in part to Id2-induced cell invasion when Id2 is accumulated to a higher level in some specific cell types. |
PDF Full Text Request