DLC3受MACC1抑制引起胃癌细胞EMT逃避代谢应激的机制

Cancer cells consume large amount of energy. When energy demand exceeds supply, metabolic stress occurs. Currently, it remains largely unknown how cancer cells resist metabolic stress. It was recently reported that metabolic stress may induce epithelial-mesenchymal transition (EMT), which is the initial step of cancer metastasis. Our previous studies reported that metabolic stress activates Metastasis-associated in colon cancer-1 (MACC1), and MACC1 promotes EMT in gastric cancer (GC). However, the detailed associated mechanisms need further exploration. Our preliminary experiments suggest: 1) metabolic stress and MACC1 respectively suppressed Deleted in liver cancer-3 (DLC3) expression; 2) DLC3 low expression indicated adverse GC prognosis; 3) silencing DLC3 enhanced GC cell motility and invasiveness. These indicate that MACC1/DLC3 axis may be the link between metabolic stress and EMT. However, either the clinical significance or biological function of DLC3 is seldom studied. Therefore, we hypothesize that DLC3 is suppressed by MACC1 under metabolic stress, and hence EMT occurs and facilitates GC cells to escape from energy deficiency. Current project will be carried out by means of clinical analysis, animal and cellular experiments, and molecular biological experiments to explore the role of MACC1/DLC3 axis on GC metastasis. The results of this project will provide the connective mechanisms between metabolic stress and EMT in GC.

肿瘤细胞需消耗大量能量，当能量供不应求时发生代谢应激。目前尚不完全清楚肿瘤细胞如何抵抗代谢应激。上皮间质转化（EMT）被认为是上皮起源的肿瘤细胞转移的起始步骤，近期研究提示代谢应激可能引起EMT。我们曾分别报道了代谢应激激活MACC1、MACC1促进胃癌细胞EMT两项成果，但尚不明确它们之间的联系。我们预实验发现：代谢应激和MACC1下调DLC3表达，DLC3低表达的胃癌预后不良，沉默DLC3后胃癌细胞迁移侵袭增强。这提示MACC1/DLC3轴可能是调控代谢应激和EMT的重要信号，但目前DLC3的临床意义及生物学功能均鲜有报道。由此我们假设：代谢应激通过MACC1抑制DLC3引起胃癌细胞EMT，进而发生转移以逃避能量缺乏的微环境。本项目拟借助临床分析、动物及细胞功能实验、分子生物学实验等手段，围绕MACC1/DLC3轴对胃癌转移的作用开展研究，阐明胃癌细胞代谢应激和EMT之间的桥梁机制。

背景：当能量供大于求时，胃癌常常发生代谢应激。有趣的是，癌细胞可以通过某种方式逃避这种应激（我们既往已对MACC1参与胃癌代谢应激调控的作用进行了证明）。已知调节细胞迁移的一些小Rho GTP酶可以被代谢应激激活。DLC3是一种RhoA特异性GTP酶活化蛋白，在癌症中功能不明确。我们假设它可能参与了代谢应激逃逸。.方法：通过葡萄糖剥夺的方式诱导胃癌细胞代谢应激，检测DLC3表达。基于临床预后分析的结果，通过差异表达DLC3在体外和体内验证其对细胞活力、运动性和糖酵解功能的影响。筛选并验证DLC3下游靶标，并进行趋化功能实验，以研究DLC3及其下游信号对代谢应激的逃逸的影响。此外，还探索了针对DLC3的治疗策略。.结果：代谢应激下调胃癌细胞DLC3的表达。DLC3低表达的癌症预后较差，沉默DLC3促进胃癌细胞增殖和侵袭。既往我们已证明MACC1是促进胃癌生长和转移的致癌基因，本实验发现MACC1是DLC3的下游靶标。 低DLC3表达和高MACC1表达的胃癌切除后更容易复发。DLC3通过RhoA/JNK/AP-1信号抑制MACC1转录调控，随后抑制胃癌细胞糖酵解和在代谢应激下的存活。 DLC3/MACC1轴调节胃癌细胞从低糖向高糖环境趋化。最后，我们发现洛伐他汀是靶向DLC3/MACC1轴的潜在治疗性药物。.结论：胃癌细胞通过DLC3/MACC1信号轴促进糖酵解和能量趋化，从而逃避代谢应激。洛伐他汀通过调控DLC3/MACC1信号抑制胃癌。