Purpose

Ascofuranone is an antiviral antibiotic that is known to exert multiple anti-tumor effects, including cell cycle arrest, inhibition of mitochondrial respiration, and inhibition of angiogenesis. In this study, we investigated the molecular mechanisms underlying the anti-metastatic effects of ascofuranone in insulin-like growth factor-I (IGF-1)-responsive cancer cells.

Methods

The inhibitory effect of ascofuranone on cancer cell migration and invasion was assessed using scratch wound healing and Matrigel invasion assays, respectively. F-actin cytoskeleton organization was assessed using FITC conjugated phalloidin staining. Target gene expression was evaluated using Western blotting and gene silencing was performed using siRNA transfections. Finally, the anti-metastatic effect of ascofuranone was investigated in vivo.

Results

We found that ascofuranone suppressed IGF-1-induced cell migration, invasion and motility in multiple cancer cell lines. The effects of ascofuranone on actin cytoskeleton organization were found to be mediated by suppression of the mTOR/p70S6K/4EBP1 pathway. Ascofuranone inhibited IGF-1-induced mTOR phosphorylation and actin cytoskeleton organization via upregulation of AMPK and downregulation of Akt phosphorylation. It also selectively suppressed the IGF-1-induced mTOR complex (mTORC)1 by phosphorylation of Raptor, but did not affect mTORC2. Furthermore, we found that focal adhesion kinase (FAK) activation decreased in response to ascofuranone, rapamycin, compound C and wortmannin treatment. Finally, we found that ascofuranone suppressed phosphorylation of FAK and mTOR and dephosphorylation of Raptor in cancerous metastatic lung tissues in vivo.

Conclusions

Our data indicate that ascofuranone suppresses IGF-1-induced cancer cell migration and invasion by blocking actin cytoskeleton organization and FAK activation through inhibition of the mTORC1 pathway, and reveal a novel anti-metastatic function of this compound.

中文翻译：

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Ascofuranone通过抑制mTOR complex 1信号通路抑制癌细胞中的侵袭和F-肌动蛋白细胞骨架的组织。

目的

Ascofuranone是一种抗病毒抗生素，已知具有多种抗肿瘤作用，包括细胞周期停滞，线粒体呼吸抑制和血管生成抑制。在这项研究中，我们调查了在胰岛素样生长因子-I（IGF-1）反应性癌细胞中阿斯科呋喃酮的抗转移作用的分子机制。

方法

分别使用刮擦伤口愈合法和Matrigel侵袭测定法评估了Asco呋喃酮对癌细胞迁移和侵袭的抑制作用。使用FITC偶联鬼笔环肽染色评估F-肌动蛋白的细胞骨架组织。使用蛋白质印迹法评估靶基因表达，并使用siRNA转染进行基因沉默。最后，体内研究了呋喃酮的抗转移作用。

结果

我们发现ascofuranone抑制了多种癌细胞系中IGF-1诱导的细胞迁移，侵袭和运动。已发现阿斯科呋喃酮对肌动蛋白细胞骨架组织的影响是通过抑制mTOR / p70S6K / 4EBP1途径介导的。Ascofuranone通过上调AMPK和下调Akt磷酸化来抑制IGF-1诱导的mTOR磷酸化和肌动蛋白细胞骨架的组织。它还通过Raptor的磷酸化选择性抑制IGF-1诱导的mTOR复合体（mTORC）1，但不影响mTORC2。此外，我们发现粘着斑激酶（FAK）激活响应于呋喃酮，雷帕霉素，化合物C和渥曼青霉素处理而降低。最后，我们发现在癌症转移性肺组织中，呋喃酮能抑制FAK和mTOR的磷酸化以及Raptor的去磷酸化体内。

结论

我们的数据表明，Ascofuranone通过抑制肌动蛋白细胞骨架组织和通过抑制mTORC1途径抑制FAK激活，从而抑制了IGF-1诱导的癌细胞迁移和侵袭，并揭示了该化合物的新型抗转移功能。