Modulation of glycogen synthase kinase-3β following TRAIL combinatorial treatment in cancer cells.
Modulation of glycogen synthase kinase-3β following TRAIL combinatorial treatment in cancer cells.
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DOI：
10.18632/oncotarget.11834
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发表时间：
2016-10-11
期刊：
影响因子：
--
通讯作者：
Rana B
中科院分区：
文献类型：
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作者：
Santha S;Davaakhuu G;Basu A;Ke R;Das S;Rana A;Rana B
糖原合成酶激酶-3 β（Glycogen Synthase Kinase-3β，GSK 3 β）是一种丝氨酸/苏氨酸激酶，已知可调节多种细胞过程，包括增殖、分化、存活、凋亡以及TRAIL抗性。因此，调控GSK 3 β轴的通路是肿瘤药物开发的重要靶点。我们早期的研究表明，曲格列酮（TZD）和TRAIL的组合治疗可以诱导TRAIL耐药癌细胞的凋亡。本研究旨在探讨GSK 3 β通路在细胞凋亡过程中是否受到调控。我们的研究结果表明，在细胞凋亡过程中，通过AKT介导的抑制性GSK 3 β Ser 9磷酸化增加。然而，在稍后的时间，TZD单独和TRAIL-TZD组合产生了GSK 3 β表达的显著降低，其被放线菌酮消除。荧光素酶活性测定结果表明，TZD能有效拮抗GSK 3 β-luc启动子活性。由于TZD是转录因子PPARγ的配体，并能激活AMPK，我们确定了它们对GSK 3 β的拮抗作用。敲低PPARγ不能恢复GSK 3 β表达或拮抗GSK 3 β Ser 9磷酸化。尽管化合物C（AMPK的药理学抑制剂）预处理部分地挽救了GSK 3 β表达，但单独或联合敲低AMPKα1或α2无效。这些研究提示TZD靶向GSK 3 β可能存在一种新的非PPARγ-AMPK依赖性机制，阐明该机制可能为我们进一步了解TRAIL耐药提供新的思路。
Glycogen Synthase Kinase-3β (GSK3β) is a serine/threonine kinase, known to regulate various cellular processes including proliferation, differentiation, survival, apoptosis as well as TRAIL-resistance. Thus pathways that can modulate GSK3β axis are important targets for cancer drug development. Our earlier studies have shown that combinatorial treatment with Troglitazone (TZD) and TRAIL can induce apoptosis in TRAIL-resistant cancer cells. The current studies were undertaken to investigate whether GSK3β pathway was modulated during this apoptosis. Our results indicated an increase in inhibitory GSK3βSer9 phosphorylation during apoptosis, mediated via AKT. At a later time, however, TZD alone and TRAIL-TZD combination produced a dramatic reduction of GSK3β expression, which was abolished by cycloheximide. Luciferase assays with GSK3β-luc promoter reporter showed that TZD can effectively antagonize GSK3β promoter activity. Since TZD is a ligand for transcription factor PPARγ and can activate AMPK, we determined their roles on antagonism of GSK3β. Knockdown of PPARγ was unable to restore GSK3β expression or antagonize GSK3βSer9 phosphorylation. Although pretreatment with Compound C (pharmacological inhibitor of AMPK) partially rescued GSK3β expression, knockdown of AMPKα1 or α2 alone or in combination were ineffective. These studies suggested a novel PPARγ-AMPK-independent mechanism of targeting GSK3β by TZD, elucidation of which might provide newer insights to improve our understanding of TRAIL-resistance.