The ability of death-inducing tumor necrosis factor-related apoptosis-inducing ligand （TRAIL） to selectively kill a variety of cancer cells has been largely described, but one of the major concerns with the treatmen...The ability of death-inducing tumor necrosis factor-related apoptosis-inducing ligand （TRAIL） to selectively kill a variety of cancer cells has been largely described, but one of the major concerns with the treatment is the occurrence of drug resistance and possible toxic side effects. Here, we report that TRAIL induces apoptosis in Jurkat and SUPT1 T cell lines and in human T-ALL blasts but not in healthy subject-derived peripheral blood mononuclear cells. In parallel, the treatment with TRAIL and Tyrphostin （AG-490）, a selective Janus kinase 2 inhibitor, produces an evident enhancement of cytotoxicity, characterized by a significant inhibition of Stat3 phosphorylation compared to controls or to TRAIL alone-treated samples, and associated with a dramatic decrease of both clAP-1 and clAP-2 mRNA levels. Downregulation of clAP-1 and cIAP-2 by specific small interference RNAs significantly amplifies TRAIL-reduced cytotoxicity. All together, these findings strongly indicate that clAP-1 and clAP-2 downregulation is a fundamental step in the signaling pathways mediating the combinatorial effect of TRAIL and AG-490 on T cell leukemia. These findings may help to open new routes for the development of less toxic pharmacological strategies in the treatment of patients affected by TRAIL-sensitive leukemias.展开更多
The human CCR4-NOT deadenylase complex consists of at least nine enzymatic and non-enzymatic subunits.Accumulating evidence suggests that the non-enzymatic subunits are involved in the regulation of mRNA deadenylation...The human CCR4-NOT deadenylase complex consists of at least nine enzymatic and non-enzymatic subunits.Accumulating evidence suggests that the non-enzymatic subunits are involved in the regulation of mRNA deadenylation,although their precise roles remain to be established.In this study,we addressed the function of the CNOT1 subunit by depleting its expression in HeLa cells.Flow cytometric analysis revealed that the sub G1 fraction was increased in CNOT1-depleted cells.Virtually,the same level of the sub G1 fraction was seen when cells were treated with a mixture of siRNAs targeted against all enzymatic subunits,suggesting that CNOT1 depletion induces apoptosis by destroying the CCR4-NOT-associated deadenylase activity.Further analysis revealed that CNOT1 depletion leads to a reduction in the amount of other CCR4-NOT subunits.Importantly,the specific activity of the CNOT6L immunoprecipitates-associated deadenylase from CNOT1-depleted cells was less than that from control cells.The formation of P-bodies,where mRNA decay is reported to take place,was largely suppressed in CNOT1-depleted cells.Therefore,CNOT1 has an important role in exhibiting enzymatic activity of the CCR4-NOT complex,and thus is critical in control of mRNA deadenylation and mRNA decay.We further showed that CNOT1 depletion enhanced CHOP mRNA levels and activated caspase-4,which is associated with endoplasmic reticulum ER stress-induced apoptosis.Taken together,CNOT1 depletion structurally and functionally deteriorates the CCR4-NOTcomplex and induces stabilization of mRNAs,which results in the increment of translation causing ER stress-mediated apoptosis.We conclude that CNOT1 contributes to cell viability by securing the activity of the CCR4-NOT deadenylase.展开更多
The anti-proliferative protein Tob belongs to the Tob/BTG family （Matsuda et al., 2001） and plays important roles in cell prolif- eration, embryonic development, cellular differentiation, cancer suppression, and apo...The anti-proliferative protein Tob belongs to the Tob/BTG family （Matsuda et al., 2001） and plays important roles in cell prolif- eration, embryonic development, cellular differentiation, cancer suppression, and apoptosis （Matsuda et al., 2001; Iwanaga et al., 2003; Ito et al., 2005; Jia and Meng, 2007; Mauxion et al.,展开更多
文摘The ability of death-inducing tumor necrosis factor-related apoptosis-inducing ligand （TRAIL） to selectively kill a variety of cancer cells has been largely described, but one of the major concerns with the treatment is the occurrence of drug resistance and possible toxic side effects. Here, we report that TRAIL induces apoptosis in Jurkat and SUPT1 T cell lines and in human T-ALL blasts but not in healthy subject-derived peripheral blood mononuclear cells. In parallel, the treatment with TRAIL and Tyrphostin （AG-490）, a selective Janus kinase 2 inhibitor, produces an evident enhancement of cytotoxicity, characterized by a significant inhibition of Stat3 phosphorylation compared to controls or to TRAIL alone-treated samples, and associated with a dramatic decrease of both clAP-1 and clAP-2 mRNA levels. Downregulation of clAP-1 and cIAP-2 by specific small interference RNAs significantly amplifies TRAIL-reduced cytotoxicity. All together, these findings strongly indicate that clAP-1 and clAP-2 downregulation is a fundamental step in the signaling pathways mediating the combinatorial effect of TRAIL and AG-490 on T cell leukemia. These findings may help to open new routes for the development of less toxic pharmacological strategies in the treatment of patients affected by TRAIL-sensitive leukemias.
基金supported by grants-in-aid from the Japan Society for the Promotion of Science and from the Ministry of Education,Culture,Sports,Science and Technology,Japan.
文摘The human CCR4-NOT deadenylase complex consists of at least nine enzymatic and non-enzymatic subunits.Accumulating evidence suggests that the non-enzymatic subunits are involved in the regulation of mRNA deadenylation,although their precise roles remain to be established.In this study,we addressed the function of the CNOT1 subunit by depleting its expression in HeLa cells.Flow cytometric analysis revealed that the sub G1 fraction was increased in CNOT1-depleted cells.Virtually,the same level of the sub G1 fraction was seen when cells were treated with a mixture of siRNAs targeted against all enzymatic subunits,suggesting that CNOT1 depletion induces apoptosis by destroying the CCR4-NOT-associated deadenylase activity.Further analysis revealed that CNOT1 depletion leads to a reduction in the amount of other CCR4-NOT subunits.Importantly,the specific activity of the CNOT6L immunoprecipitates-associated deadenylase from CNOT1-depleted cells was less than that from control cells.The formation of P-bodies,where mRNA decay is reported to take place,was largely suppressed in CNOT1-depleted cells.Therefore,CNOT1 has an important role in exhibiting enzymatic activity of the CCR4-NOT complex,and thus is critical in control of mRNA deadenylation and mRNA decay.We further showed that CNOT1 depletion enhanced CHOP mRNA levels and activated caspase-4,which is associated with endoplasmic reticulum ER stress-induced apoptosis.Taken together,CNOT1 depletion structurally and functionally deteriorates the CCR4-NOTcomplex and induces stabilization of mRNAs,which results in the increment of translation causing ER stress-mediated apoptosis.We conclude that CNOT1 contributes to cell viability by securing the activity of the CCR4-NOT deadenylase.
文摘The anti-proliferative protein Tob belongs to the Tob/BTG family （Matsuda et al., 2001） and plays important roles in cell prolif- eration, embryonic development, cellular differentiation, cancer suppression, and apoptosis （Matsuda et al., 2001; Iwanaga et al., 2003; Ito et al., 2005; Jia and Meng, 2007; Mauxion et al.,
