The Effects And Mechanisms Of Triptolide On Cell Cycle And Apoptosis In Human Multiple Myeloma Rpmi-8226 Cells

Objective: To observe the effects of triptolide on cell proliferation,cell cycle and cell apoptosis in human multiple myeloma RPMI-8226 cells in vitro, and explore the mechanisms.Methods: The effect of triptolide on the growth of RPMI-8226 cells was studied by 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyl-2H-tetrazolium (MTT) assay. Apoptosis was detected through Annexin V-FITC/PI double-labeled cytometry and Hoechst33258 staining assay. A propidium iodide method was used to study cell cycle distribution by FACS. The expression levels of P21wap1/cip1 and P27kip1 were studied by flow reverse transcription-polymerase chain reaction (RT-PCR). Western boltting was employed to assess the protein expression of P21wap1/cip1,P27kip1,NF-κB/p65 and IκBα.The subcellular distributions of NF-κB/p65 and IκBαwere detected through confocal microscopy. .Results: (1) Triptolide treatment resulted in a does- and time-dependent inhibition of proliferation of RPMI-8226 cells, the IC50 value for 36h was 121.76±2.01nmol/L. (2) Triptoliede caused a dose-related apoptosis in RPMI-8226 cells, which accompanied with typical apoptotic morphological changes. (3) Triptolide induced cell-cycle arrest in G0/G1 phase in RPMI-8226 cells. (4) Triptolide increased the protein and transcription expression of p21wap1/cip1 and p27kip1 in RPMI-8226 cells in dose-dependent manner. Triptolide treatment down-regulated the protein expression of NF-κB/p65 and up-regulated IκBα. (5) Triptolide changed the subcellular distributions of NF-κB/p65 and IκBαin RPMI-8226 cells,IκBαwas increased in the cytoplasm and NF-κB/p65 was decreased in the nuclei.Conclusion: Triptolide presented the effects on proliferation inhibition, cell-cycle arrest and induction apoptosis in RPMI-8226 cells. The mechanism might be involved in the regulation of the expression levels of p21wap1/cip1,p27kip1,NF-κB/p65 and IκBα.