The proliferation, migration, and cellular morphology of vascular smooth muscle cells (VSMCs) play important roles in the pathogenesis of atherosclerosis (AS). Homocysteine (Hcy) is a sulfur-containing amino acid, which is an intermediate product of methionine metabolism. Hcy can induce proliferation, migration, and phenotypic switch of VSMCs, but details of these mechanisms are still unclear. The phosphatidylinositol 3-kinase (PI3K/Akt/mTOR) signaling pathway is involved in a host of cellular functions. In this study, we sought to determine if this multifunctional pathway played a role in Hcy-induced proliferation, migration, and phenotypic transformation of VSMCs, which has not been previously reported. miR-145 has been previously reported to suppress the effects of Hcy in VSMCs. In our study, using qRT-PCR, we found that Hcy itself reduced the expression of miR-145 in VSMCs, while overexpression of miR-145 reduced the proliferation, migration, and phenotypic transformation of VSMCs caused by Hcy. Using Western blot analysis, we found that VSMCs exposed to Hcy exhibited significant increases in the levels of PI3K, Akt, and mTOR proteins. Additionally, overexpression of miR-145 dramatically decreased PI3K, Akt, and mTOR expression. Using qRT-PCR we found that miR-145 expression increased after blocking PI3K using an inhibitor. Inhibition of the PI3K signaling pathway also prevented Hcy-induced VSMC proliferation, migration, and phenotypic switch. Taken together, our results suggest that miR-145 could inhibit VSMC proliferation, migration, and phenotype switching by preventing activation of the PI3K/Akt/mTOR signaling pathway.

中文翻译：

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MiR-145通过抑制PI3K / Akt / mTOR途径减轻Hcy诱导的VSMC增殖，迁移和表型转换。

血管平滑肌细胞（VSMC）的增殖，迁移和细胞形态在动脉粥样硬化（AS）的发病机理中起重要作用。同型半胱氨酸（Hcy）是一种含硫氨基酸，是蛋氨酸代谢的中间产物。Hcy可以诱导VSMC增殖，迁移和表型转换，但是这些机制的细节仍不清楚。磷脂酰肌醇3-激酶（PI3K / Akt / mTOR）信号通路参与许多细胞功能。在这项研究中，我们试图确定这种多功能途径是否在Hcy诱导的VSMC增殖，迁移和表型转化中起作用，这一点以前尚未见报道。先前已经报道了miR-145抑制Hcy在VSMC中的作用。在我们的研究中，使用qRT-PCR，我们发现，Hcy本身降低了VSMC中miR-145的表达，而miR-145的过表达降低了Hcy引起的VSMC的增殖，迁移和表型转化。使用蛋白质印迹分析，我们发现暴露于Hcy的VSMC的PI3K，Akt和mTOR蛋白水平显着增加。此外，miR-145的过表达显着降低了PI3K，Akt和mTOR表达。使用qRT-PCR，我们发现使用抑制剂阻断PI3K后，miR-145表达增加。PI3K信号通路的抑制也阻止了Hcy诱导的VSMC增殖，迁移和表型转换。两者合计，我们的结果表明，miR-145可以通过阻止PI3K / Akt / mTOR信号通路的激活来抑制VSMC增殖，迁移和表型转换。