Diallyl trisulfide, a constituent of processed garlic, inactivates Akt to trigger mitochondrial translocation of BAD and caspase-mediated apoptosis in human prostate cancer cells
Diallyl trisulfide, a constituent of processed garlic, inactivates Akt to trigger mitochondrial translocation of BAD and caspase-mediated apoptosis in human prostate cancer cells
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DOI：
10.1093/carcin/bgi228
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发表时间：
2006-03-01
期刊：
影响因子：
4.7
通讯作者：
Singh, SV
中科院分区：
文献类型：
--
作者：
Xiao, D;Singh, SV
我们以前已经证明，加工大蒜的成分二烯丙基三硫化物(DATS)诱导PC-3和DU145人前列腺癌PC-3和DU145细胞凋亡与c-Jun氨基末端激酶和细胞外信号调节激酶介导的Bcl-2磷酸化有关。然而，对这些激酶的药理抑制只能对DATS引起的细胞死亡提供部分保护。在这里，我们证明了DATS使Akt失活，从而引发前列腺癌细胞的凋亡。用诱导凋亡浓度的DATS(40mU M)处理PC-3/DU145细胞后，Akt的Ser(473)和Thr(308)磷酸化水平迅速下降，从而抑制了Akt的活性。DATS介导的Akt失活与胰岛素样生长因子受体1蛋白水平下调及其自磷酸化抑制有关。DATS处理(40mM)还导致Akt下游靶蛋白BAD的Ser(155)和Ser(136)磷酸化水平降低。由于增加了与14-3-3蛋白的结合，磷酸化在细胞质中滞留。40 mU DATS作用4 h后，BAD与14-3-3β之间的相互作用明显减弱。免疫细胞化学显示，DATS处理(40MU M，4h)促进了BAD的线粒体易位，这与上述结果一致。成分活性Akt的异位表达对DATS诱导的细胞凋亡具有统计学意义的保护作用。在PAN caspase抑制剂zVAD-fmk和caspase 9特异性抑制剂zLEHD-fmk存在下，DATS诱导的两种细胞的凋亡均显著减弱。综上所述，本研究表明，DATS诱导的人前列腺癌细胞的凋亡至少部分是通过Akt信号轴的失活来介导的。
We have shown previously that apoptosis induction by diallyl trisulfide (DATS), a constituent of processed garlic, in PC-3 and DU145 human prostate cancer cells is associated with c-Jun N-terminal kinase and extracellular signal-regulated kinase-mediated phosphorylation of Bcl-2. However, pharmacological inhibition of these kinases offers only partial protection against the cell death caused by DATS. Here, we demonstrate that DATS inactivates Akt to trigger apoptosis in prostate cancer cells. Treatment of PC-3/DU145 cells with apoptosis inducing concentration of DATS (40 mu M) resulted in a rapid decrease in Ser(473) and Thr(308) phosphorylation of Akt leading to inhibition of its kinase activity. The DATS-mediated inactivation of Akt was associated with downregulation of insulin-like growth factor receptor 1 protein level and inhibition of its autophosphorylation. DATS treatment (40 mu M) also caused a decrease in Ser(155) and Ser(136) phosphorylation of BAD (a proapoptotic protein), which is a downstream target of Akt. Phosphorylation sequesters BAD in the cytoplasm owing to increased binding with 14-3-3 proteins. The interaction between BAD and 14-3-3 beta was reduced markedly upon a 4 h treatment with 40 mu M DATS in both cell lines. Consistent with these results, DATS treatment (40 mu M, 4 h) promoted mitochondrial translocation of BAD as revealed by immunocytochemistry. Ectopic expression of constitutively active Akt conferred statistically significant protection against DATS-induced apoptosis. The DATS-induced apoptosis in both cell lines was significantly attenuated in the presence of pan caspase inhibitor zVAD-fmk and caspase 9 specific inhibitor zLEHD-fmk. In conclusion, the present study demonstrates that DATS-induced apoptosis in human prostate cancer cells is mediated, at least in part, by inactivation of Akt signaling axis.