Ceramide metabolism and the regulation of TGF-beta receptor signaling to control metastasis

摘要 转化生长因子β受体I/II(T？RI/II)信号在质膜上被激活 (PM)通过配体结合，诱导SMAD3/4依赖(规范)或独立的细胞迁移、侵袭 和/或转移。当Smad3/4被激活时，Smad7结合并抑制T？RI/II信号。初级纤毛是 在不影响细胞运动的情况下介导细胞间通讯和迁移/侵袭的PM突起 通过激活各种信号通路，如Sonic Hedgehog(Shh)。神经酰胺是一种具有生物活性的神经鞘糖脂 具有肿瘤抑制信号功能，神经酰胺合成酶4(CerS4)产生长链C18/20- 神经酰胺。然而，神经酰胺代谢、Smad7募集和TüRI/II之间的任何机制联系 在初级纤毛膜上调节肿瘤转移的信号仍不清楚。基于 我们的新的和未发表的初步数据，我们设计这个应用程序来测试一个新的假设 CerS4/神经酰胺通过Smad7选择性地抑制原纤毛膜上T？RI/II的转运和信号转导 以调节细胞的迁移、侵袭和/或转移。提出了以下具体目标：目标1) 明确神经酰胺通过Smad7调节T？RI/II信号的机制；目标2)确定 神经酰胺/Smad7抑制复合体调节T？RI/II转运至初级纤毛的机制； 目的3)剖析初级纤毛T？RI/II信号转导致癌的下游机制 CerS4/神经酰胺/Smad7轴改变与肿瘤转移的关系总体而言，基于我们在 癌症信号和脂质代谢，我们处于独特的位置来开发基于新机制的 选择性地靶向/抑制初级纤毛中TüRI/II信号的策略，这将有助于减弱 肿瘤转移不影响转化生长因子-B信号的典型功能(降低一般毒性)，使用 创新的分子/药理学工具、遗传模型和临床标本。

SUMMARY Transforming growth factor beta receptor type I/II (TßRI/II) signaling is activated on the plasma membrane (PM) by ligand binding, inducing Smad3/4-dependent (canonical) or independent cell migration, invasion and/or metastasis. While Smad3/4 activates, Smad7 binds and inhibits TßRI/II signaling. Primary cilia are protrusions of PM that mediate cell-to-cell communication and migration/invasion without affecting cell motility by activating various signaling pathways such as sonic hedgehog (Shh). Ceramide is a bioactive sphingolipid with tumor suppressive signaling functions, and ceramide synthase 4 (CerS4) generates long chain C18/20- ceramide. However, any mechanistic link between ceramide metabolism, Smad7 recruitment and TßRI/II signaling at the primary cilium membrane for the regulation of tumor metastasis remains unknown. Based on our novel and unpublished preliminary data, we designed this application to test a novel hypothesis that CerS4/ceramide inhibits TßRI/II trafficking and signaling selectively at the primary cilia membrane via Smad7 to modulate cell migration, invasion and/or metastasis. The following Specific Aims are proposed: Aim 1) Define the mechanisms by which ceramide regulates TßRI/II signaling by Smad7; Aim 2) Determine the mechanisms by which ceramide/Smad7 inhibitory complex regulates TßRI/II trafficking to the primary cilia; and Aim 3) Dissect the downstream mechanism by which TßRI/II signaling at primary cilia induces tumor metastasis in response to alterations of the CerS4/ceramide/Smad7 axis. Overall, based on our expertise in cancer signaling and lipid metabolism, we are uniquely positioned to develop novel mechanism-based strategies for targeting/inhibiting TßRI/II signaling selectively in primary cilium, which then will help attenuate tumor metastasis without affecting canonical functions of TGF-ß signaling (reducing general toxicity), using innovative molecular/pharmacologic tools, genetic models, and clinical specimens.