miRNA 依赖调控 AKT1 磷酸化。

miRNA-Dependent Regulation of AKT1 Phosphorylation.

机构信息

Department of Biochemistry, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 5C1, Canada.

Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 5C1, Canada.

出版信息

Cells. 2022 Feb 26;11(5):821. doi: 10.3390/cells11050821.

The phosphoinositide-3-kinase (PI3K)/AKT pathway regulates cell survival and is over-activated in most human cancers, including ovarian cancer. Following growth factor stimulation, AKT1 is activated by phosphorylation at T308 and S473. Disruption of the AKT1 signaling pathway is sufficient to inhibit the epithelial-mesenchymal transition in epithelial ovarian cancer (EOC) cells. In metastatic disease, adherent EOC cells transition to a dormant spheroid state, characterized previously by low S473 phosphorylation in AKT1. We confirmed this finding and observed that T308 phosphorylation was yet further reduced in EOC spheroids and that the transition from adherent to spheroid growth is accompanied by significantly increased levels of let-7 miRNAs. We then used mechanistic studies to investigate the impact of let-7 miRNAs on AKT1 phosphorylation status and activity in cells. In growth factor-stimulated HEK 293T cells supplemented with let-7a, we found increased phosphorylation of AKT1 at T308, decreased phosphorylation at S473, and enhanced downstream AKT1 substrate GSK-3β phosphorylation. Let-7b and let-7g also deregulated AKT signaling by rendering AKT1 insensitive to growth factor simulation. We uncovered let-7a-dependent deregulation of PI3K pathway components, including PI3KC2A, PDK1, and RICTOR, that govern AKT1 phosphorylation and activity. Together, our data show a new role for miRNAs in regulating AKT signaling.

磷酸肌醇 3-激酶（PI3K）/AKT 途径调节细胞存活，在大多数人类癌症中过度激活，包括卵巢癌。在生长因子刺激后，AKT1 通过 T308 和 S473 的磷酸化而被激活。AKT1 信号通路的破坏足以抑制上皮性卵巢癌（EOC）细胞的上皮-间充质转化。在转移性疾病中，附着的 EOC 细胞向休眠球体状态转变，先前 AKT1 中的 S473 磷酸化水平较低。我们证实了这一发现，并观察到 EOC 球体中 T308 磷酸化进一步降低，并且从附着到球体生长的转变伴随着 let-7 miRNAs 水平的显著增加。然后，我们使用机制研究来研究 let-7 miRNAs 对细胞中 AKT1 磷酸化状态和活性的影响。在生长因子刺激的 HEK 293T 细胞中补充 let-7a 时，我们发现 AKT1 的 T308 磷酸化增加，S473 磷酸化减少，并且下游 AKT1 底物 GSK-3β 的磷酸化增强。let-7b 和 let-7g 也通过使 AKT1 对生长因子模拟不敏感而使 AKT 信号失调。我们发现 let-7a 依赖性地调节 PI3K 途径成分，包括 PI3KC2A、PDK1 和 RICTOR，它们控制 AKT1 的磷酸化和活性。总之，我们的数据显示了 miRNA 在调节 AKT 信号中的新作用。