Department of Urology, Goethe‑University, D‑60590 Frankfurt am Main, Germany.
Department of Vascular and Endovascular Surgery, Goethe‑University, D‑60590 Frankfurt am Main, Germany.
Mol Med Rep. 2017 Nov;16(5):7064-7071. doi: 10.3892/mmr.2017.7401. Epub 2017 Aug 31.
Mechanistic target of rapamycin (mTOR) signaling is typically increased in hepatocellular carcinoma (HCC). A panel of HCC cell lines (HepG2, Hep3B and HuH6) was exposed to various concentrations of the mTOR inhibitors, everolimus and temsirolimus, in order to investigate their effects on cell growth, clonal formation, cell cycle progression, and adhesion and chemotactic migration using MTT and clonal cell growth assays, fluorometric detection of cell cycle phases and a Boyden chamber assay. In addition, integrin α and β adhesion receptors were analyzed by flow cytometry and blocking studies using function blocking monoclonal antibodies were conducted to explore functional relevance. The results demonstrated that everolimus and temsirolimus significantly suppressed HCC cell growth and clonal formation, at 0.1 or 1 nM (depending on the cell line). In addition, the number of cells in G0/G1 phase was increased in response to drug treatment, whereas the number of G2/M phase cells was decreased. Drug treatment also considerably suppressed HCC cell adhesion to immobilized collagen. Integrin profiling revealed strong expression of integrin α1, α2, α6 and β1 subtypes; and integrin α1 was upregulated in response to mTOR inhibition. Suppression of integrin α1 did not affect cell growth; however, it did significantly decrease adhesion and chemotaxis, with the influence on adhesion being greater than that on motility. Due to a positive association between integrin α1 expression and the extent of adhesion, whereby reduced receptor expression was correlated to decreased cell adhesion, it may be hypothesized that the adhesion‑blocking effects of mTOR inhibitors are not associated with mechanical contact inhibition of the α1 receptor but with integrin α1‑dependent suppression of oncogenic signaling, thus preventing tumor cell‑matrix interaction.
雷帕霉素靶蛋白(mTOR)信号通常在肝细胞癌(HCC)中增加。将一组 HCC 细胞系(HepG2、Hep3B 和 HuH6)暴露于不同浓度的 mTOR 抑制剂依维莫司和替西罗莫司中,以使用 MTT 和克隆细胞生长测定法、荧光检测细胞周期相和 Boyden 室测定法研究它们对细胞生长、克隆形成、细胞周期进程以及粘附和趋化性迁移的影响。此外,通过流式细胞术分析整合素α和β粘附受体,并进行功能阻断单克隆抗体阻断研究以探索功能相关性。结果表明,依维莫司和替西罗莫司在 0.1 或 1 nM(取决于细胞系)显著抑制 HCC 细胞生长和克隆形成。此外,药物处理后 G0/G1 期细胞数量增加,而 G2/M 期细胞数量减少。药物处理还显著抑制 HCC 细胞对固定化胶原的粘附。整合素分析显示整合素α1、α2、α6 和β1 亚型的强烈表达;并且整合素α1 在 mTOR 抑制下上调。抑制整合素α1不影响细胞生长;然而,它显著降低粘附和趋化性,对粘附的影响大于对运动性的影响。由于整合素α1表达与粘附程度之间存在正相关,其中受体表达减少与细胞粘附减少相关,因此可以假设 mTOR 抑制剂的粘附阻断作用与α1 受体的机械接触抑制无关,而是与整合素α1 依赖性抑制致癌信号有关,从而防止肿瘤细胞-基质相互作用。