Inhibition of p70 S6 kinase (S6K1) activity by A77 1726 and its effect on cell proliferation and cell cycle progress.
Inhibition of p70 S6 kinase (S6K1) activity by A77 1726 and its effect on cell proliferation and cell cycle progress.
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DOI：
10.1016/j.neo.2014.08.006
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发表时间：
2014-10
期刊：
影响因子：
4.8
通讯作者：
Xu, Xiulong
中科院分区：
文献类型：
--
作者：
Doscas, Michelle E.;Williamson, Ashley J.;Usha, Lydia;Bogachkov, Yedida;Rao, Geetha S.;Xiao, Fei;Wang, Yimin;Ruby, Carl;Kaufman, Howard;Zhou, Jingsong;Williams, James W.;Li, Yi;Xu, Xiulong
来氟米特是一种治疗类风湿关节炎的新型免疫调节药物。它抑制蛋白酪氨酸激酶和二氢乳清酸脱氢酶（嘧啶核苷酸合成途径中的限速酶）的活性。在这里，我们报告说，A77 1726，来氟米特的活性代谢产物，抑制核糖体蛋白S6和其他两个底物的S6 K1，胰岛素受体底物-1和氨甲酰磷酸合成酶2，在A375黑色素瘤细胞系的磷酸化。A77 1726通过反馈激活IGF-1受体介导的信号通路增加AKT、p70 S6（S6 K1）、ERK 1/2和MEK的磷酸化。体外激酶试验显示，来氟米特和A77 1726抑制S6 K1活性，IC 50值分别约为55和80 μM。外源性尿苷可部分阻断A77 1726对A375细胞增殖的抑制作用。S6 K1基因敲低导致A375细胞增殖的抑制，但不增强A77 1726的抗增殖作用。A77 1726刺激A375细胞中的溴脱氧尿苷掺入，但将细胞周期阻滞在S期，添加外源尿苷或MAP激酶途径抑制剂可逆转该周期，但雷帕霉素和LY 294002（一种磷酸肌醇3-激酶抑制剂）却不能逆转该周期。这些观察结果表明，A77 1726加速细胞周期进入S期通过MAP激酶激活和嘧啶核苷酸耗尽停止完成细胞周期。我们的研究确定了A77 1726的一个新的分子靶点，并表明S6 K1活性的抑制是其抗增殖活性的部分原因。我们的研究还提供了一个新的机制洞察A77 1726诱导的细胞周期停滞在S期。
Leflunomide is a novel immunomodulatory drug prescribed for treating rheumatoid arthritis. It inhibits the activity of protein tyrosine kinases and dihydroorotate dehydrogenase, a rate-limiting enzyme in the pyrimidine nucleotide synthesis pathway. Here, we report that A77 1726, the active metabolite of leflunomide, inhibited the phosphorylation of ribosomal protein S6 and two other substrates of S6K1, insulin receptor substrate-1 and carbamoyl phosphate synthetase 2, in an A375 melanoma cell line. A77 1726 increased the phosphorylation of AKT, p70 S6 (S6K1), ERK1/2, and MEK through the feedback activation of the IGF-1 receptor–mediated signaling pathway. Invitro kinase assay revealed that leflunomide and A77 1726 inhibited S6K1 activity with IC50 values of approximately 55 and 80 μM, respectively. Exogenous uridine partially blocked A77 1726–induced inhibition of A375 cell proliferation. S6K1 knockdown led to the inhibition of A375 cell proliferation but did not potentiate the antiproliferative effect of A77 1726. A77 1726 stimulated bromodeoxyuridine incorporation in A375 cells but arrested the cell cycle in the S phase, which was reversed by addition of exogenous uridine or by MAP kinase pathway inhibitors but not by rapamycin and LY294002 (a phosphoinositide 3-kinase inhibitor). These observations suggest that A77 1726 accelerates cell cycle entry into the S phase through MAP kinase activation and that pyrimidine nucleotide depletion halts the completion of the cell cycle. Our study identified a novel molecular target of A77 1726 and showed that the inhibition of S6K1 activity was in part responsible for its antiproliferative activity. Our study also provides a novel mechanistic insight into A77 1726–induced cell cycle arrest in the S phase.
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影响因子：
11.5
作者：
Sahin, F;Kannangai, R;Torbenson, M
通讯作者：
Torbenson, M
影响因子：
5.7
作者：
Baumann, Philipp;Mandl-Weber, Sonja;Schmidmaier, Ralf
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Schmidmaier, Ralf
影响因子：
6.2
作者：
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Finnegan, A
影响因子：
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作者：
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Tanaka, Yoshiya
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作者：
Bruneau, JM;Yea, CM;Ruuth, E
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Ruuth, E