脂肪酸代谢通路FASN/FABP4促进卵巢癌腹腔网膜转移的作用及机制

Ovarian cancer has a clear predilection for metastasis to the omentum, which effects on the prognosis. Recent research has shown that fatty acid metabolic abnormalities associated with tumor metastasis. Our previous studies have shown that ovarian cancer express the high expression of fatty acid synthase (FASN) are found in ovarian cancer and promote the metastasis of ovarian cancer cell. .Bioinformatics data showed that the expression of fatty acid binding protein FABP4 was highly consistent with FASN expression in ovarian cancer. Moreover, what is interesting that there is relatively higher expression of FABP4 in tissues of ovarian cancer with omental metastasis and its omental metastases tissue. Our founding suggested that the fatty acid metabolism of protein FASN/FABP4 may play an important role in omental metastases of ovarian cancer. Therefore, we hypothesized that in primary ovarian cancer cells, higher expression of FASN promote metastasis, and then induced FABP4 expression. Ovarian cancer cell with expression of FABP4 can used the fatty acids for rapid tumor growth in omentum. The project intends to explore the mechanism of FASN on ovarian cancer cell metastasis by overexpression and silencing FASN method combinated with co-immunoprecipitation. Using the co-culture system of ovarian cancer cells and adipocyte, we will detect the mechanism of FASN induced FABP4 expression and clarify the role of FABP4 on ovarian cancer cell metastasis to the omentum through binding with fatty acids. Finally, we will dynamically observe the tumor development and omental metastasis in the ovarian cancer tumor-bearing mice through transplantation model of ovarian cancer in situ and in vivo imaging techniques. This project will characterize the detailed role and mechanism of lipid metabolism proteins in ovarian cancer omental metastasis, which can provide a new target and new idea to benefit the treatment of ovarian cancer.

卵巢癌易发生腹腔网膜转移，是高致死率的主要原因。已有研究显示脂肪酸代谢异常与肿瘤转移相关，我们前期研究表明卵巢癌高表达脂肪酸合成酶FASN并促进转移，生物信息学数据鉴定发现卵巢癌中脂肪酸结合蛋白FABP4与FASN表达相关，有意思的是FABP4相对高表达在有网膜转移的卵巢癌组织和其网膜转移组织，这提示脂肪酸代谢蛋白FASN/FABP4可能参与卵巢癌网膜转移。因此我们提出假设：卵巢癌细胞高表达FASN促进转移，同时调控FABP4表达有利于卵巢癌细胞结合脂肪酸形成网膜种植转移。本项目拟通过过表达/沉默FASN结合IP等实验明确FASN促进转移的机制；构建卵巢癌细胞和脂肪细胞共培养模型，研究FASN调控FABP4表达对卵巢癌细胞克隆生长的作用；最后通过卵巢癌转移模型和活体成像技术动态观察荷瘤小鼠卵巢癌网膜转移情况。本项目将阐明脂肪酸代谢蛋白促进卵巢癌腹腔网膜转移的机制，为临床治疗提供新思路。

卵巢癌是严重威胁女性健康的最常见恶性肿瘤之一，容易发生侵袭转移，其中腹腔网膜转移率发生较高，因此研究卵巢癌腹腔网膜转移的分子机制具有重要的理论意义和临床应用价值。能量代谢异常是肿瘤的十大特征之一。本研究项目鉴定发现了脂肪酸合成酶FASN促进卵巢癌腹腔网膜转移的作用及具体分子机制。. 本项目首先证实FASN可促进卵巢癌细胞的转移能力增强。FASN沉默表达的卵巢癌细胞转移能力明显减低，FASN 过表达细胞呈现EMT表型改变，有利于转移侵袭。而且FASN促进卵巢癌细胞的转移能力与细胞骨架的重构相关。FASN 过表达可显著增加细胞骨架重构重要功能蛋白RHOA-GTP的表达，进而通过RHOA信号通路调控细胞骨架重构促进卵巢癌细胞的转移。进一步通过检测虫荧光素酶转录活性发现，FASN可直接调控脂肪细胞型脂肪酸结合蛋白（FABP4）启动子的转录活性，诱导FABP4蛋白表达。免疫组织化学检测也证实，FASN和FABP4在网膜转移部位的卵巢癌肿瘤细胞显著高表达，高度相关。体内小鼠腹腔转移实验也证实，沉默表达FASN的卵巢癌细胞的体内腹腔侵袭转移显著降低。FASN高表达卵巢癌小鼠腹水或卵巢癌细胞上清可诱导树突状DC细胞脂质沉积，其抗原呈递和激活T细胞增殖功能显著减低，这表明FASN不仅直接促进卵巢癌细胞侵袭转移，而且可通过脂质代谢紊乱功能诱导肿瘤微环境内DC细胞功能异常，调控机体免疫抑制促进卵巢癌发生发展的重要作用。. 该研究鉴定发现FASN是卵巢癌腹腔网膜转移的关键基因，阐明了FASN不仅通过调控上皮间质转化和细胞骨架蛋白重构促进卵巢癌细胞从原发部位转移的新机制，而且可调控FABP4的表达促使转移性卵巢癌细胞在脂肪富集的腹腔网膜部位种植克隆生长。在该研究项目的基础上，结合FASN自身调控脂质代谢异常的特征，发现FASN可调控肿瘤免疫微环境中树突状细胞DC脂质累积抑制其功能，导致肿瘤细胞的免疫逃逸。FASN对卵巢癌细胞以及免疫微环境的双重作用的发现，为临床提供了卵巢癌转移及预后判断的新指标和将来可能的治疗靶目标。