文本框: THE STUDY OF THE EFFECT OF TPCK IN TNF-a INDUCED APOPTOSIS IN THE HUMAN MONOCYTIC LEUKEMIA U937 CELL LINE Chen WH, Peng GJ, Tang AP, Wang KY, Liu SY, Zhang LQ, Wang LY Tongji Hospital, Tongji Medical College, Huazhong University of Science d and Technology, Wuhan, China Objective: To explore the role of TPCK in TNF-αinduced nuclear factor-kB(NF-kB)activation and apoptosis of U937 cell line. Method: N-tosyl-L-phenylalanylchloromethyl ketone (TPCK), a protease inhibitor, was used. U937 cells were cultured and divided into control group，TPCK treatment group ,TNF-a stimulation group and TPCK+TNF-a group. The nuclear translocation of NF-κB/p65 protein was detected by indirect Immunolfluorescence. The degradation of IκB-αprotein was detected by indirect Immunol fluorescence and flow cytometry (FCM) . The apoptosis of U937 cell was measured by flow cytometry and electrophoresis of DNA. Results: The average fluorescence intensity of IkB-αprotein of TNF-a stimulation group detected by FCM was significantly lower than that of control group (P<0.01).The average fluorescence intensity of IkB-αprotein of TPCK+TNF-a group was significantly higher than that of TNF-αgroup (P<0.01). The percentages of apoptosis of TNF-αstimulation group were significantly higher than that of TPCK+TNF-αgroup (P<0.01). The DNA ladder can be detected both in groups treated by TNF-αand in cells treated by TPCK+TNF-α,but the ladder of the former was more obvious than that of the latter. Conclusion: TPCK can modulate NF-κB activation and apoptosis induced by TNF-α in U937 cells. TPCK sensitive proteases play an important role in these processes. 0977