Objective： To investigate the effects of triptolide（TPL） on cell growth, cell cycle and the expressions of p21wapl/cipl and p27kipl. Methods： MTT assay was used to determine the cell viability after triptolide treatment in human multiple myeloma RPMI-8226 cells. The effect on cell cycle distribution was determined by flow cytometry. Semi-quantitative reverse transcription-PCR was used to examine the mRNA expressions of p21wapl/cipl and p27kipl. The protein expressions of p21 wapl/cipl and p27kipl were determined by Western blot. Results： Triptolide of varying concentrations induced cell viability inhibition in dose- and time-related fashion and caused Go- G1 phase arrest of cell cycle progression in RPMI-8226 cells. These effects accompanied with up-modulation of the expressions of p21 wapl/cipl and p27kipl. Conclusion： These results suggest that triptolide inhibit cell proliferation and cell cycle progression via up-regulating p21wapl/cipl and p27kipl and triptolide may exert its anti-cancer activity through this pathway.
Yuan Liu Ling-lan Zeng Yan Chen Fei Zhao Rui Li Chun Zhang Lu Wen
Objective： Multiple myeloma is a kind of malignant plasma cell disease that originated from B lymphocyte and secrete great amount of monoclonal immunoglobulin. It is still one of the refractory diseases at present. Numerous studies show that there is an intensive relationship between the disequilibrium of histone acetylation and the occurance of multiple myeloma. Here we investigated the effect of triptolide（TPL） on the proliferation, apoptosis, histone H3 and H4 acetylation and expression of histone deacetylase 8 （HDAC8） in vitro, to explore its anti- myeloma mechanism. Methods： The effect of triptolide on the growth of RPMI8226 was studied by 3-（4,5-Dimethyl-2-thiazolyl） -2,5-diphenyl-2H-tetrazolium（MTT） assay. Apoptosis was detected by Hoechst 33258 staining. The protein expressions of acetyl-histone H3 and H4 were determined by Western blot, and the expression of HDAC8 was assessed by RT-PCR, Western blot and confocal microscopy. Results： Triptolide inhibited the proliferation of RPMI8226 and induced apoptosis in a time- and dosedependent manner. The 36h IC50 value was （105.370 ± 0.189）nmol/L. Triptolide increased the acetylation of histone H3 and H4 greatly. Furthermore, triptolide significantly down-regulated the mRNA and protein expression of HDAC8. Conclusion： Triptolide can inhibit proliferation and induce apoptosis of RPMI8226 significantly. Triptolide reduces the expression of HDAC8 in order to increase the histone H3 and H4 acetylation, which is possibly the anti-myeloma mechanism of triptolide.
Fei Zhao Ling-lan Zeng Yan Chen Rui Li Yuan Liu Lu Wen Yi-quan Cheng Chun Zhang
The effect of triptolide on proliferation and apoptosis of human multiple myeloma RPMI-8226 cells in vitro,as well as the roles of nuclear factor-kappa B（NF-κB） and IκBα was investigated.The effect of tritptolide on the growth of RPMI-8226 cells was studied by MTT assay.Apoptosis was detected by Hoechest 33258 staining and Annexin V/PI double staining assay.The expression of NF-κB and IκBα was observed by Western blot and confocal microscopy.The results showed that triptolide inactivated NF-κB apoptotic pathway in human multiple myeloma RPMI-8226 cells.Triptolide at nM range induced proliferation inhibition in a dose-and time-dependent manner and apoptosis in a dose-dependent fashion in RPMI-8226 cells.Besides,we observed the inhibition of NF-κB /p65 in the nuclear fraction was correlated with the increase in the protein expression of IκBα in the cytosol.These results suggested that triptolide might exhibit its strong anti-tumor effects via inactivation of NF-κB/p65 and IκBα.
