DEPTOR-mTOR通路在结肠炎相关结直肠癌中的作用及谷氨酰胺的调节机制

mTOR plays an important role in tumor cell growth, differentiation, invasion and metastasis. DEPTOR is a newly discovered endogenous regulator of the mTOR pathway which could effectively regulate the expression of mTOR. As an important regulator, DEPTOR-mTOR signaling pathway takes part in the sustained chronic inflammation and in the occurrence and development of tumor, but its effects in colitis-associated colorectal cancer (CAC) is still uncovered and yet needs studies to clarify. Glutamine shows its activity in regulating mTOR pathway and attenuates inflammation in animal model of ulcerative colitis as it was recently reported. Preliminary studies carried out by our group indicated disorder changes of DEPTOR-mTOR pathway in the CAC mice model. Our results also showed glutamine could effectively reduce colonic inflammation and suppress the occurrence of CAC, but its mechanism is not clear which still warrant further research. Based on previous results of our group, we now proposed a project by using immunohistochemistry, molecular biology technology and molecular immunology techniques to explore the mechanisms of DEPTOR-mTOR signaling pathway in CAC and the effects of glutamine on this pathway both in vivo and in vitro studies. This study aimed to evaluate the changes of DEPTOR-mTOR signaling pathway in CAC and discover the pathogenesis of CAC, and furthermore, to explore the regulatory role of glutamine on DEPTOR-mTOR signaling pathway and to provide a theoretical basis for revealing the prevention effects of glutamine on CAC. Our results may support new evidence in the pathophysiology of the CAC and the treatment targets for the prevention and treatment of CAC.

DEPTOR是新近发现的mTOR通路的内源性负调控因子，已知DEPTOR-mTOR信号通路在慢性炎症及肿瘤的发生及发展中起到重要作用，但其在结肠炎相关结直肠癌（CAC）中的作用尚不明了。谷氨酰胺具有调节mTOR通路、治疗结直肠炎症的作用。本课题组前期研究发现CAC模型小鼠DEPTOR-mTOR通路出现异常改变，应用谷氨酰胺能够有效减轻结肠炎症、抑制CAC的发生，但其作用机制尚不明确。在前期研究基础上，本课题以CAC患者组织标本、CAC模型小鼠和人结直肠癌细胞株为研究对象，应用在体和离体研究相结合的方法，采用免疫组化、分子生物学以及分子免疫学等技术，以DEPTOR-mTOR信号通路为切入点，观测DEPTOR-mTOR信号通路在CAC中的变化，并深入探索谷氨酰胺对DEPTOR-mTOR信号通路的调节作用，以期揭示谷氨酰胺防治CAC的可能机制，并为临床防治CAC提供新的治疗方法及靶点。

DEPTOR是新近发现的mTOR通路的内源性负调控因子，DEPTOR-mTOR信号通路在慢性炎症及肿瘤的发生及发展中起到重要作用。谷氨酰胺具有调节mTOR通路、治疗结直肠炎症的作用。本课题组前期研究发现结肠炎相关结直肠癌（colitis-associated colorectal cancer, CAC）模型小鼠DEPTOR-mTOR通路出现异常改变，而谷氨酰胺能够有效减轻结肠炎症、抑制CAC的发生。我们推测，谷氨酰胺可能通过调节DEPTOR的表达来影响mTOR信号通路，谷氨酰胺调节DEPTOR-mTOR信号通路可能是其防治CAC的重要机制之一。为验证这一假设，本课题以CAC患者组织标本、CAC模型小鼠和人结直肠癌细胞株为研究对象，应用在体和离体研究相结合的方法，采用免疫组化、分子生物学以及分子免疫学等技术，以DEPTOR-mTOR信号通路为切入点，观测DEPTOR-mTOR信号通路在CAC中的变化，并深入探索谷氨酰胺对DEPTOR-mTOR信号通路的调节作用，以期揭示谷氨酰胺防治CAC的可能机制，并为临床防治CAC提供新的治疗方法及靶点。. 本课题研究结果表明：CAC模型小鼠出现DEPTOR-mTOR信号通路的紊乱，DEPTOR和mTOR的表达变化呈现负相关。通过基因沉默的方式可以阻断DEPTOR表达并调控下游mTOR等因子的表达变化，谷氨酰胺干预可以降低炎症分子的表达，改变了DEPTOR-mTOR信号通路的活化状态，及其下游因子p-mTOR、Raptor等也随之发生了相应变化。CAC患者肠道粘膜组织DEPTOR和下游分子如mTOR和p-mTOR表达出现异常。谷氨酰胺能够直接影响结直肠癌细胞系DEPTOR–mTOR信号通路的活性，并调节其下游因子p-mTOR、Raptor、Rictor等的表达。表明DEPTOR-mTOR信号通路参与了CAC模型小鼠的发病过程，谷氨酰胺能够通过调节DEPTOR-mTOR信号通路而影响肠道的炎癌转化过程。