World J Gastroenterol. 2012 Feb 21;18(7):601-8. doi: 10.3748/wjg.v18.i7.601.
Epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions are well established biological events which have an important role in not just normal tissue and organ development, but in the pathogenesis of diseases. Increasing evidence has established their presence in the human colon during colorectal carcinogenesis and cancer invasion, chronic inflammation-related fibrosis and in the course of mucosal healing. A large body of evidence supports the role for transforming growth factor-β and its downstream Smad signaling, the phosphatidylinositol 3'-kinase/Akt/mTOR axis, the Ras-mitogen-activated protein kinase/Snail/Slug and FOXC2 pathway, and Hedgehog signaling and microRNAs in the development of colorectal cancers via epithelial-to-mesenchymal transition. C-met and Frizzled-7, among others, seem to be the principle effectors of mesenchymal-to-epithelial transition, hence have a role not just in mucosal regeneration but in the progression of colonic wall fibrosis. Here we discuss a role for these pathways in the initiation and development of the transition events. A better understanding of their induction and regulation may lead to the identification of pathways and factors that could be potent therapeutic targets. The inhibition of epithelial-to-mesenchymal transition using mTOR kinase inhibitors targeting the ATP binding pocket and which inhibit both mTORC1 and mTORC2, RNA aptamers or peptide mimetics, such as a Wnt5A-mimetic, may all be useful in both cancer treatment and delaying fibrosis, while the induction of mesenchymal-to-epithelial transition in induced pluripotent stem cells may enhance epithelial healing in the case of severe mucosal damage. The preliminary results of the current studies are promising, but more clinical investigations are needed to develop new and safe therapeutic strategies for diseases of the colon.
上皮-间充质和间充质-上皮转化是已被充分证实的生物学事件,它们不仅在正常组织和器官发育中具有重要作用,而且在疾病的发病机制中也具有重要作用。越来越多的证据表明,它们在人类结肠的结直肠癌变和癌症侵袭、慢性炎症相关纤维化以及黏膜愈合过程中存在。大量证据支持转化生长因子-β及其下游 Smad 信号转导、磷脂酰肌醇 3'-激酶/Akt/mTOR 轴、Ras-有丝分裂原激活蛋白激酶/Snail/Slug 和 FOXC2 途径以及 Hedgehog 信号转导和 microRNAs 通过上皮-间充质转化在结直肠癌的发生发展中发挥作用。C-met 和 Frizzled-7 等似乎是间充质-上皮转化的主要效应物,因此不仅在黏膜再生中发挥作用,而且在结肠壁纤维化的进展中也发挥作用。在这里,我们讨论这些途径在过渡事件的启动和发展中的作用。更好地了解它们的诱导和调节可能会导致确定可能成为有效治疗靶点的途径和因素。使用针对 ATP 结合口袋的 mTOR 激酶抑制剂(抑制 mTORC1 和 mTORC2)、RNA 适体或肽模拟物(如 Wnt5A 模拟物)抑制上皮-间充质转化,可能在癌症治疗和延迟纤维化方面都很有用,而在诱导多能干细胞中诱导间充质-上皮转化可能会增强严重黏膜损伤情况下的上皮愈合。目前研究的初步结果很有希望,但需要更多的临床研究来为结肠疾病开发新的、安全的治疗策略。