Effect Of The DLL4/Notch1Signaling Pathway On Growth Of The Leukemia Cell Line K562Cells

Objective: To investigate effects of the Notch1expression on cellproliferation and apoptosis when the DLL4was over-expressed in humanchronic myeloid leukemia cell line K562cells.Methods: The cells are divided into three groups：normal control group(un-transfected group),negative control group(BudCE4.1transfectedgroup) and experimental group(pBudCE4.1-DLL4transfected group).48hoursafter transfected into K562cells by lipofectamine2000with each groupof plasmid, RT-PCR and Western blot were applied to monitor the mRNA andprotein expression of exogenous DLL4.Meanwhile,immunofluorescencestaining for fluorescence microscopy demonstrated that DLL4protein couldbe detected in cell membrane and cytoplasm of transfectedcells,indicating successful expression of DLL4in K562cells.48hoursafter transfection, RT-PCR and Western blot were also applied to monitorthe mRNA and protein expression of NICD and target gene Hes1, indicatingthe activation of the Notch1signaling pathway in K562cells transfectedwith exogenous DLL4gene. Cell Counting Kit-8was used to detect theproliferation of K562cells and flow cytometry was used to detect the cellapoptosis.Results:48hours after transfected into K562cells by lipofectamine2000with each group of plasmids,the mRNA and protein expression levers of DLL4,NICD and Hes1of the experimental group cells were significantly more thancontrol groups(p<0.05,and it was statistically significant),and the DLL4protein was located in the surface membranes and cytoplasm of K562cells.It turned out that the Notch1signaling pathway of K562cells wasactivated succesfully by the exogenous DLL4gene.The proliferation ofexperimental group cells was inhibited obviously when detected by CCK-8（P＜0.05，it was statistically significan）,and the number of apoptotic cells were increased than control groups when detected by flowcytometry(p<0.05, and it was statistically significant).Conclusion: The proliferation of DLL4-expressing K562cells weresuppressed and the apoptosis was enhanced.