PDTC In TRAIL Induced Raji Cells Apoptosis

Objective:To investigate whether PDTC could increase the Raji cells apoptosis induced by TRAIL and investigate the underlying mechanism.Methods:Using MTT assay to measure the cell growth inhibiting rate of Raji cell induced by TRAIL(1 ng/ml,10 ng/ml,100ng/ml ),PDTC(100μmol/ml)and TRAIL ( 1 ng/ml,10 ng/ml,100ng/ml ) combined with PDTC(100μmol/ml).The Raji cells apoptosis indix was examined by terminal deoxynucleotide transferas-mediated aUTP nick end labeling(TUNEL) .The expression of Membrane Proteins DR4,DR5 and nuclear protein NF-κB were detected by Western blot before and after the treatment of TRAIL,PDTC and co-treated with TRAIL and PDTC for 24h.Results:1. The 12h inhibiting rate of 1ng/ml,10ng/ml TRAIL was -35.52±5.64(%)and -15.07±2.03(%), the 12h inhibiting rate of 100ng/ml TRAIL was 6.68±1.17(%) and showed a time-dependent.The 12h inhibiting rate of 100μmol/mlPDTC was 1.01±0.21(%) and The 48 h inhibiting rate was 2.12±0.33(%),which showed a no significant inhibition on Raji cells.The 12 h inhibiting rate of TRAIL(1,10,100ng/ml)combined with the PDTC were 1.18±0.51,4.96±1.34,14.63±2.57(%),and were all markedly higher than in TRAIL and PDTC used alone(p<0.01).2. The co-treated group,TRAIL(100ng/ml)group and 100μmol/ml PDTC group after 48 h were all showed significantly different to control group(p<0.05).The highest apoptosis index of Raji cells induced by TRAIL combined with the PDTC was 79.49±1.40(%) which markedly higher than TRAIL100ng/ml(28.84±2.47%). The apoptosis index of Raji cell in 1ng/ml,10ng/ml TRAIL combined with the PDTC were also markedly higher than TRAIL and PDTC used alone (P<0.01)and also showed a time-dependent, which consistent of MTT.3.The expression of Membrane Proteins DR4,DR5 after treated with TRAIL(1,10,100ng/ml)for 24 h showed significantly diference in control group(P<0.05,p<0.01,p<0.01),but had no significantly difference in TRAIL co-treat with PDTC (p>0.05). The expression of nuclear protein NF-κB in control group is zero,but in TRAIL(1,10,100ng/ml) treated group was 0.7835±0.019,0.6607±0.0310,0.5194±0.024 which were all markedly higher than TRAIL co-treated with PDTC ( 0.3377±0.046,0.4837±0.012,0.6578±0.025). The Membrane Proteins DR4,DR5 and nuclear protein NF-κB at 100μmol/mlPDTC group were same as cotrol group.Conclusions:1. Raji cell is insensitive to TRAIL, PDTC could significantly increase the killing effect of TRAIL in Raji cell.2. The TUNEL show that PDTC primarily through increasing tumor cells apoptosis to enhance the killing effect of TRAIL.3. This study verified that TRAIL could establish a complex with death receptors and at the same time activate NF-κB.PDTC through significantly decrease the activation of NF-κB to increase the sensitiveity of TRAIL-induced apoptosis in Raji cell and the expression of death receptor not involved in this process.