Research On Multiple Myeloma Cell Apoptosis By Inhibition Of MTORC2and Chaperon Pathways

Background and Objective:Multiple myeloma (MM) is a malignant disease which characterized by the proliferation of monoclonal plasma cells in bone marrow. Due to the tumor cells’ long proliferation time and their resistance to multidrug chemotherapy, the clinical curative effect is unimpressive, thus MM is still considered to be an incurable disease.And recent study found that the occurrence and development of MM has closely connection with mTORC2pathways and chaperon pathways.Both of them can regulate AKT.This study explores apoptosis of multiple myeloma cells and its mechanism by the common inhibition of mTORC2signaling pathway and heat shock protein90.It will probably provide a new potential way for clinical treatment of MM.Methods:The effect of Rapamycin,17-AAG and the combination of them on proliferation of multiple myeloma cell line U266and KM3were assessed using MTT in different time (0hour,8hour,24hour,48hour). Cell morphology was observed by optical microscopy and cell viability was determined by the trypan blue dye exclusion.Cell apoptosis and cell cycle distribution were measured by Flow cytometry.The specific protein AKT was detected by Western Blotting.Results:Rapamycin,17-AAG and the combination of them can suppress the proliferation of multiple myeloma cell line U266and KM3, especially the combination of Rapamycin and17-AAG synergistically inhibited proliferation (P<0.05); Rapamycin induced G1arrest both at24hours and48hours,17-AAG also induced G1arrest, especially at48hours(P<0.0001); Rapamycin,17-AAG alone can decrease the expression of AKT and induce myeloma cell apoptosis to some extent (P<0.0001); Inhibition of mTORC2and chaperon pathways can destabilize AKT and induce myeloma cell apoptosis, the apoptosis rate was significantly higher than that of any single drug (P<0.0001).Conclusion:1. Inhibition of mTORC2and chaperon pathways can destabilize AKT in multiple myeloma cells;2. Inhibition of mTORC2and chaperon pathways will induce apoptosis of multiple myeloma cells in vitro.