基于肿瘤多胺代谢及MYC/HIF1通路激活探讨大肠癌恶性进程中肠上皮屏障功能障碍的发生机制及左金丸的干预作用

Intestinal epithelial barrier dysfunction in the malignant progression of colorectal cancer is closely related to tumor load and affects its treatment and prognosis. Previous studies have shown that Zuojin pills can effectively inhibit tumor growth and reduce intestinal mucosal permeability in hct116 bearing mice, but the mechanism is unclear.It is now known that : MYC / HIF1 pathway is involved in glycolysis to provide energy for tumor growth. MYC up-regulates the expression of HIF1, but under hypoxia conditions, the synthesis of polyamines necessary for colorectal cancer growth which is positively regulated by MYC decreases and the uptake of exogenous polyamines increases. As polyamines are the key factors to protect intestinal epithelial barrier,combined with previous studies, exogenous polyamines can promote glycolysis of tumor cells. It is suggested that activation of the Myc / HIF1 pathway is an important mechanism of intestinal epithelial barrier dysfunction in the malignant process of colorectal cancer. Regulating the metabolism of polyamines in tumor to inhibit the Myc/HIF1 pathway is the target of ZuoJin Pill.In order to confirm the hypothesis, we intend to use cell coculture RNA interference and overexpression techniques, combined with tumor-bearing nude mice to carry out in vitro and in vivo experiments. To observe the effect of polyamine metabolism and activation of MYC/HIF1 pathway on intestinal epithelial barrier function and the intervention effect of Zuojin pills during the process of colorectal cancer, and to provide evidence for elucidating the mechanism of intestinal epithelial barrier dysfunction and the clinical application of Zuo Jin pills.

大肠癌恶性进程中肠上皮屏障功能障碍与肿瘤负荷密切相关，影响其治疗和预后。前期研究表明，左金丸能有效抑制荷瘤鼠肿瘤生长并降低肠黏膜通透性，但机制不明。目前已知：MYC/HIF1通路参与糖酵解为肿瘤生长提供能量，MYC上调HIF1表达，但缺氧条件下，作为大肠癌生长所必需的与Myc存在正反馈调节的肿瘤多胺合成减少，对外源性多胺摄取增加；由于多胺是保护肠上皮屏障的关键因素，结合前期研究外源性多胺能促进肿瘤细胞糖酵解，由此提出：MYC/HIF1通路激活是大肠癌恶性进程中肠上皮屏障功能障碍的重要机制，调节肿瘤多胺代谢以抑制Myc/HIF1通路是左金丸的作用靶点。为证实假说，拟利用细胞共培养、RNA干扰及过表达技术、结合荷瘤裸鼠进行体内外实验，观察大肠癌进程中肿瘤多胺代谢及MYC/HIF1通路激活对肠上皮屏障功能的影响及左金丸的干预作用，为阐明大肠癌肠上皮屏障功能障碍发生机制及左金丸新的临床应用提供依据

大肠癌恶性进程中肠上皮屏障功能障碍与肿瘤负荷密切相关，影响其治疗和预后。前期研究表明，左金丸能有效抑制荷瘤鼠肿瘤生长并降低肠黏膜通透性，但机制不明。目前已知：MYC/HIF1通路参与糖酵解为肿瘤生长提供能量，MYC上调HIF1表达，但缺氧条件下，作为大肠癌生长所必需的与Myc存在正反馈调节的肿瘤多胺合成减少，对外源性多胺摄取增加；由于多胺是保护肠上皮屏障的关键因素，结合前期研究外源性多胺能促进肿瘤细胞糖酵解，由此提出：MYC/HIF1通路激活是大肠癌恶性进程中肠上皮屏障功能障碍的重要机制，调节肿瘤多胺代谢以抑制MYC/HIF1通路是左金丸的作用靶点。为证实假说，采用细胞共培养、HIF1沉默及过表达技术、结合荷瘤裸鼠进行体内外实验，观察大肠癌进程中肿瘤多胺代谢及MYC/HIF1通路激活对肠上皮屏障功能的影响及左金丸的干预作用，为阐明大肠癌肠上皮屏障功能障碍发生机制及左金丸新的临床应用提供依据。.细胞实验结果表明随着肿瘤细胞生长时间的延长，其自身多胺合成逐渐下降，存在着对肠上皮细胞多胺的掠夺，破坏肠上皮屏障，以Hif1α OE组最为明显，体内实验同样表明Hif1α激活促进肿瘤的生长，从而使肠上皮屏障功能受损，荷瘤鼠体重下降。肿瘤掠夺的外源性多胺通过MYC/HIF1通路参与糖酵解为其生长提供能量。补充外源性多胺在缓解肿瘤生长引起的肠上皮屏障受损的同时也促进了肿瘤的生长，这表明对于肠上皮屏障功能障碍引起的肿瘤恶病质或许可以给予多胺缓解症状，但治标不治本。多途径抑制肿瘤多胺含量、抑制肿瘤对肠黏膜多胺的掠夺以抑制其糖酵解在治疗大肠癌恶性进程中肠上皮屏障功能障碍中具有重要的作用，这也是左金丸保护大肠癌恶性进程中肠上皮屏障功能的重要机制，并且早期阶段治疗效果好于晚期。本项目阐明了大肠癌恶性进程中肠上皮屏障障碍发生的机制，并为其防治提供参考。