CARMIL3在肿瘤生长和转移中的重要作用和机制研究

The three members of the CARMIL family have well conserved domains but they have divergent functions. While CARMIL1 and CARMIL2 have been studied extensively, little is known about the biological properties and functions of CARMIL3. Through clinical studies and bioinformatic analysis of a large number of human cancer samples deposited in TCGA, we found that CARMIL3 gene mutations are widespread in many types of cancers. However, there are not any indepth studies on the role of CARMIL3 in cancer. We for the first time systematically revealed the key role of CARMIL3 in tumor cell growth and metastasis in mouse models of breast and prostate cancers. CARMIL3 knockdown results in a dramatic reduction in the expression of both E-cadherin and beta-catenin, both of which are key molecules involved in epithelial mesenchymal transition and cancer metastasis. This project will explore in great depth the new functions and molecular mechanisms of CARMIL3 in cancer cell growth and metastasis in vitro and in vivo. We will address two key questions: (1) How does CARMIL3 affect tumor cell growth and metastasis by regulating the ubiquitin-dependent proteasomal degradation of its target proteins? (2) How does CARMIL3 promote tumor growth through regulating cell cycle progression, apoptosis and its potential interaction with the immune system?

CARMIL家族的三个成员具有丰富的保守结构域但功能各异。CARMIL1和CARMIL2的功能已有相当多的报道但关于CARMIL3的生物学特性和功能则知之甚少。我们基于TCGA大量临床癌症样本的生物信息学分析发现CARMIL3基因突变在许多类型的癌症中广泛存在。但CARMIL3在癌症中的作用尚无任何深入研究。我们通过系统的研究首次揭示了CARMIL3在乳腺癌和前列腺癌小鼠模型中肿瘤细胞生长尤其是转移中的重大作用。CARMIL3基因敲除导致上皮钙粘蛋白和连环蛋白的表达极大程度地降低，这两者都是涉及上皮间质转化和癌症转移功能的关键分子。本项目将通过体内和体外实验更深入地探究CARMIL3在癌症生长和转移中的新功能与分子机制：（1）CARMIL3如何通过调节泛素依赖的蛋白酶体降解目标蛋白来影响肿瘤细胞的转移？（2）CARMIL3如何通过调节细胞周期，细胞凋亡和免疫系统互动促进肿瘤细胞生长？

我们之前曾报道过，被我团队首次鉴定为癌胚样基因的封端蛋白调节剂和肌球蛋白 1 接头 3 (CARMIL3) 是通过调节质膜附近的肌动蛋白细胞骨架动力学来转移乳腺癌和前列腺癌细胞所必需的。在过去的一年中，我们进一步揭示了 CARMIL3 的另一种新功能，它是吞噬凋亡细胞和/或暴露于脂多糖 (LPS) 的巨噬细胞中几种关键促炎细胞因子转录的重要调节因子。 CARMIL3 缺陷型巨噬细胞表达强烈废除水平的白细胞介素 (IL)-6、TNF-α、IL-1β 和 IL-23 以响应 LPS，而 IL-10 表达增强。 对用 LPS 刺激的 CARMIL3 缺陷型和野生型 (WT) RAW264.7 细胞进行的 RNA-seq 分析揭示了许多差异表达的基因，影响了几个重要的炎症通路。 在分子水平上，CARMIL3 缺陷导致 LPS 激活的核因子-κB (NF-κB) 信号通路严重受损，IKKα/β 和 IκBα 磷酸化降低，p65 蛋白水平严重降低。 这项新研究揭示了 CARMIL3 通过调节吞噬细胞中主要细胞因子的产生来影响炎症和组织稳态之间平衡的关键作用。