Effects Of PS-341 And CS055 On Caspase Apoptosis Pathway And NF-κB Regulation In T-cell Lymphoma Cell Lines

Objective:To study the effect of induction of apoptosis,growth arrest and the inhibition of NF-κB signal transduction pathway in the T-cell lymphoma cell lines with the treatment of PI and HDACi.Material and Methods:The acute lymphoblastic lymphoma cell lien Jurkat and CTCL cell line HuT 78 was treated with PI(PS-341) and HDACi(CS055).The apoptosis and growth arrest under the different concentration of drugs used as single-agent or in combination were tested with Annexin V/PI and MTT, respectively.The GI₅₀ value was measured with results of MTT experiments. Western Blot was applied to detect the expression of several proteins,including caspase-8/-9,and phosphorylated-IκBαin the cytoplasm and p65 in the nucleus.The efficacy of pro-apoptosis with PS-341 and CS055 in both Jurkat and HuT 78 cells was evaluated after the pan-caspase inhibitor z-VAD was used to block the caspase-dependent apoptosis pathway.Results:PS-341 and CS055 could induce apoptosis and arrest the cell growth in Jurkat cells.The GI₅₀ of these two drugs was 40nM and 5μM after 24 hours(hrs) of the administration,respectively. Furthermore,PS-341 and CS055 worked synergistically on growth arrest: the GI₅₀ of PS-341 reduced to 2.5nM when combined with 5μM CS055.As to HuT 78 cells,the apoptosis was able to detected at 36 hrs,and was enhanced at 48 hrs with both PS-341 and CS055.Along with the prolongation of drug reaction time,the concentration of PS-341 and CS055 inducing 50%apoptosis was reduced from 20hM and 1.25μM to 1.25nM and 0.32μM,respectively.The GI₅₀ of CS055 in HuT 78 cells at 48 hrs was 20μM.However,PS-341 single-agent didn't show significant effect on growth arrest.PS-341 20nM and CS055 5μM,or their combination could activate caspase-8/-9 in Jurkat cells with Western Blot,and the expression of nuclear p65 was decreased when they used together,z-VAD couldn't inhibit the apoptosis induced by CS055 used alone,although it was blocked in PS-341 single or PS-341 plus CS055.The caspse-9 activation in HuT 78 was not observed under the influence of PS-341 20nM,CS055 1.25μM or their combination.The cleaved caspase-8 was detected after 48 hrs of CS055 administration. The nuclear p65 expression of HuT 78 was reduced dramatically with single CS055。z-VAD-FMK could block the apoptosis induced by PS-341 and CS055 at both 24 hrs and 48 hrs in HuT 78 cell line.Conclusion:PS-341 and CS055 could induce apoptosis and arrest growth in Jurkat cell line,and they affected the cell growth synergistically. These two drugs had pro-apoptosis effect on HuT 78.PS-341 used alone couldn't inhibit cell proliferation significantly in the MTT experiment.PS-341 and CS055 were able to repress the expression of nuclear p65 in Jurkat when they used together,and CS055 alone could do this better than either PS-341 alone or PS-341 plus CS055 could do.It is possible that CS055 induce apoptosis in Jurkat via a caspase-independent pathway.