State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
Cancer Chemother Pharmacol. 2013 Oct;72(4):799-808. doi: 10.1007/s00280-013-2255-1. Epub 2013 Aug 10.
Mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in regulating cell growth, proliferation and survival. Dysregulation of mTOR signaling pathway is closely involved in cancer development and chemotherapy resistance. Inhibitors of mTOR signaling pathway have been demonstrated to be attractive therapeutics for cancer therapy. In the present study, we aim to discover novel mTOR signaling pathway inhibitors from a natural compound library.
Inhibitors of mTOR signaling pathway were discovered via high content screen assay based on the subcellular localization of eukaryotic initiation factor 4E (eIF4E) in mouse embryonic fibroblast cells. Candidate compounds were further assessed in cancer cells. Phosphorylation levels of mTOR complexes downstream targets were analyzed using Western blot. Cell cytotoxicity and apoptosis were evaluated using MTS assay and flow cytometry, respectively.
Two compounds, 1,4-O-diferuloylsecoisolariciresinol (IM-1) and Pierreione B (IM-2), were identified which induced significant nuclear translocation of eIF4E in a panel of cancer cells. Both of the compounds decreased the phosphorylation levels of p70 ribosomal protein S6 kinase (S6K) and eIF4E binding protein 1 (4E-BP1), resulting in cancer cell cytotoxicity and apoptosis.
Via high content screen assay, two novel inhibitors of mTOR signaling, IM-1 and IM-2, were identified with strong anticancer activity. IM-1 and IM-2 could be potential candidates for anticancer therapeutics by targeting mTOR signaling pathway and as such warrants further exploration.
哺乳动物雷帕霉素靶蛋白（mTOR）信号通路在调节细胞生长、增殖和存活方面起着关键作用。mTOR 信号通路的失调与癌症的发展和化疗耐药密切相关。mTOR 信号通路抑制剂已被证明是癌症治疗的有吸引力的治疗方法。在本研究中，我们旨在从天然化合物库中发现新型 mTOR 信号通路抑制剂。
通过基于真核起始因子 4E（eIF4E）在小鼠胚胎成纤维细胞中的亚细胞定位的高内涵筛选测定，发现 mTOR 信号通路抑制剂。在癌细胞中进一步评估候选化合物。使用 Western blot 分析 mTOR 复合物下游靶标的磷酸化水平。使用 MTS 测定和流式细胞术分别评估细胞细胞毒性和细胞凋亡。
鉴定出两种化合物，1,4-O-二阿魏酰基-secoisolariciresinol（IM-1）和 Pierreione B（IM-2），它们在一系列癌细胞中诱导 eIF4E 显著核易位。这两种化合物均降低了 p70 核糖体蛋白 S6 激酶（S6K）和 eIF4E 结合蛋白 1（4E-BP1）的磷酸化水平，导致癌细胞细胞毒性和细胞凋亡。
通过高内涵筛选测定，鉴定出两种新型 mTOR 信号抑制剂，IM-1 和 IM-2，具有很强的抗癌活性。IM-1 和 IM-2 可能通过靶向 mTOR 信号通路成为潜在的抗癌治疗候选药物，因此值得进一步探索。
