Contact inhibition and its disruption of vascular smooth muscle cells (VSMCs) are important cellular events in vascular diseases. But the underlying molecular mechanisms are unclear. In this study we investigated the roles of microRNAs (miRNAs) in the contact inhibition and its disruption of VSMCs and the molecular mechanisms involved. Rat VSMCs were seeded at 30% or 90% confluence. MiRNA expression profiles in contact-inhibited confluent VSMCs (90% confluence) and non-contact-inhibited low-density VSMCs (30% confluence) were determined. We found that multiple miRNAs were differentially expressed between the two groups. Among them, miR-145 was significantly increased in contact-inhibited VSMCs. Serum could disrupt the contact inhibition as shown by the elicited proliferation of confluent VSMCs. The contact inhibition disruption accompanied with a down-regulation of miR-145. Serum-induced contact inhibition disruption of VSMCs was blocked by overexpression of miR-145. Moreover, downregulation of miR-145 was sufficient to disrupt the contact inhibition of VSMCs. The downregulation of miR-145 in serum-induced contact inhibition disruption was related to the activation PI3-kinase/Akt pathway, which was blocked by the PI3-kinase inhibitor LY294002. KLF5, a target gene of miR-145, was identified to be involved in miR-145-mediated effect on VSMC contact inhibition disruption, as it could be inhibited by knockdown of KLF5. In summary, our results show that multiple miRNAs are differentially expressed in contact-inhibited VSMCs and in non-contact-inhibited VSMCs. Among them, miR-145 is a critical gene in contact inhibition and its disruption of VSMCs. PI3-kinase/Akt/miR-145/KLF5 is a critical signaling pathway in serum-induced contact inhibition disruption. Targeting of miRNAs related to the contact inhibition of VSMCs may represent a novel therapeutic approach for vascular diseases.

中文翻译：

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MicroRNA表达谱和功能分析揭示了它们在大鼠血管平滑肌细胞的接触抑制及其破坏转换中的作用。

接触抑制及其对血管平滑肌细胞（VSMC）的破坏是血管疾病中的重要细胞事件。但是潜在的分子机制尚不清楚。在这项研究中，我们研究了microRNA（miRNA）在接触抑制及其对VSMC的破坏中的作用以及涉及的分子机制。以30％或90％的融合度接种大鼠VSMC。确定了在接触抑制的融合VSMC（90％融合）和非接触抑制的低密度VSMC（30％融合）中的miRNA表达谱。我们发现，两组miRNA差异表达。其中，miR-145在接触抑制的VSMC中显着增加。血清可能破坏接触抑制作用，这是由融合的VSMC引起的。接触抑制破坏伴有miR-145的下调。血清诱导的VSMC接触抑制破坏被miR-145的过表达所阻断。此外，miR-145的下调足以破坏VSMC的接触抑制。miR-145在血清诱导的接触抑制破坏中的下调与激活PI3-激酶/ Akt通路有关，该通路被PI3-激酶抑制剂LY294002阻断。已鉴定出miR-145的靶基因KLF5参与了miR-145介导的对VSMC接触抑制的破坏作用，因为它可能被KLF5的敲低所抑制。总之，我们的结果表明，多种miRNA在接触抑制型VSMC和非接触抑制型VSMC中差异表达。其中，miR-145是接触抑制及其破坏VSMC的关键基因。PI3-激酶/ Akt / miR-145 / KLF5是血清诱导的接触抑制破坏中的关键信号通路。与VSMCs的接触抑制有关的miRNA的靶向可能代表血管疾病的一种新的治疗方法。