ABSTRACT
The zinc finger protein A20 exists in many kinds of ceils in the body and plays multiple roles in physiological and pathological processes such as regulation of immune response,inflammatory diseases and cancers by inhibiting cell apoptosis induced by tumor necrosis factor (TNF) and restricting NFKB signaling pathway.Recently,the role of A20 in generation and development of tumors draws wide attention,hence,we summarized recent research progress of the relation between A20 and cancer in this review.
ABSTRACT
Objective To study the effect and related mechanism of celecoxib on tumor necrosis factorrelated apoptosis-inducing ligand(TRAIL) induced apoptosis of medullary thyroid cancer TT cell line.Methods MTT assay was used to measure the growth inhibition induced by TRAIL and celecoxib alone and their combination.TT cell cycle distribution was analyzed by flowcytometry.Hochest33258 staining and DNA ladder was used to detect the apoptosis of drug combination on TT cells.Western blot was used detect the protein change of cyclin A,Cdk2,caspase-8,c-FLIP,and RIP.Results ①MTT showed the growth inhibition ratio of TT cell intervened by the combination of TRAIL and celecoxib was 47.53％ ± 1.34％,which was much higher than that intervened by TRAIL(7.75 ％ ± 3.84％)and celecoxib alone.The differences had statistical significance (t test,F =5.234,P ＜0.01);②PI detection found the cells' number in G0/G1 phase in celecoxib group and combination group were increased compared to that in control group and TRAIL group(F =242.694,P ＜ 0.01);③Western blot indicated the expression of Cyclin A and Cdk2 were down regulated,there was no statistic significance;④ The apoptosis morph in nuclus was detected by Hochest33258 staining and showed the karyopycnosis and muclear fragmentation were increased in combination group with the apoptosis rate 24.23％ ± 2.91％,which was much higher than that in TRAIL(5.86％ ± 1.41％) and celecoxib(20％ ± 1.24％) (t test,F =1.824,P ＜0.01),the difference has statistic significance;⑤Western blot illustrated the active schizolysis of casplase-8 was higher and the expression of c-FLIP and RIP was down regulated in combination group.Conclusion celecoxib plays a positive effect on TRAIL-reduced apoptosis of medullary thyroid cancer TT cell line,which may due to the cell cycle arrest at G0/G1 phase,down-regulation of c-FLIP and RIP and subsequent activation of caspase-8.
ABSTRACT
Objective To observe the level of autophagy induced by TRAIL in TT cell line and identify the role of autophagy in TRAIL-inducing apoptosis of TT cell line.Methods The growth inhibition of TT cells was measured by MTT assay.MDC staining was used to identify the happening of autophagy.Annexin V/PI double staining was used to analyze the apoptosis rate of TT cells by flowcytometry.The protein expression of caspase-8 and Beclin1 was detected by Western blot.Results ① The growth inhibition ratio of TT cells induced by TRAIL at the concentration of 250,500,1000 and 2000 ng/ml was (3.02 ± 1.82)％,(4.87 ± 1.45)％,(7.51 ± 1.57) ％,(12.76 ± 3.23) ％ respectively,which suggested significant resistance of TT cells to TRAIL.② MDC-labeled green light vesicles was significantly increased after the treatment of TRAIL for 48 h.③ The apoptosis rate of TT cells induced by TRAIL at the concentration of 500 ng/ml and 1000 ng/ml after the pretreat ment of 3-MA for 4 h was(17.83 ± 1.54) ％ and(27.81 ± 1.79) ％ respectively,which was significantly higher than the apoptosis rate induced by TRAIL(3.70 ± 0.34) ％,(6.55 ± 0.59) ％ alone and that induced by 3-MA(7.71 ± 0.64) ％ (t =3.282,P ＜ 0.05 ; t =7.830,P ＜ 0.01).④ The combination treatment of TRAIL and 3-MA increased the cleavage of caspase-8 and down-regulated the expression of Beclin 1.Conclusion Autophagy induced by TRAIL may contributes to the resistance of TT cells to TRAIL,which can be reversed by the inhibition of autophagy.