The Effects Of Blocking Notch Signal Pathway By DAPT On The Proliferation And Apoptosis In RPMI8226Human Multiple Myeloma Cell Line

Object: To investigate the effects of blocking Notch signal pathway by γ-secretasespecific inhibitor DAPT on the proliferation and apoptosis in RPMI8226humanmultiple myeloma cell line harboring constitutive active Notch and to explore theunderlying mechanisms.Methods: multiple myeloma cell line RPMI8226was treated with DAPT in differentdoses,Cell Counting Kit-8was used to detect cell proliferation,the cells was detectedby flow cytometry for cell cycle distribution and apoptosis,Western blot for theprotein expression level of N intracellular domain (NICD), down stream geneHes1,anti-apoptosis protein Bcl-2and apoptosis protein Bax,Semi-quantitativeanalysis was performed for the expression of these proteins, using SPSS statisticalsoftware for data processing.Results：1. The growth and proliferation of human multiple myeloma cells decreasedsignificantly after DAPT treatment (P<0.05), DAPT produced concentrationdependent antiproliferative effects on RPMI8226cells.48hours after DAPTtreatment could block cell cycle at G0/G1phase (p<0.05), and increase the number ofapoptotic cells were increased(p<0.05), it was statistically significant.2. the proteinexpression lever of NICD, Hes1,and Bcl-2decreased significantly after DAPTtreatment, however the protein expression lever of Bax increased significantly,(p<0.05), and it was statistically significant.Conclusions：1. DAPT could significantly inhibit the proliferation of RPMI8226cellsin dose dependent manner in vitro.The inhibition mechanisms were associated withblocking cell cycle at G0/G1phase.2. DAPT could induce the apoptosis ofRPMI8226cells in vitro.3. DAPT’s action of inhibing growth and inducing apoptosisin RPMI8226cells might be related with the down-regulation of Notch1、Hes1and Bcl-2protein expression as well as up-regulation of the protein expression of Bax.