SIRT3/IDH2/FAS轴调控乳腺癌脂肪酸合成代谢重编程的作用与机制研究

Breast cancer is one of the most prevalent malignancies in women.Metabolic reprogramming of fatty acid synthesis promotes the proliferation and metastasis of breast cancer cells, but its mechanism of regulation is still unclear. Our previous study showed abnormal expression of Silent information regulator 3 (SIRT3),isocitrate dehydrogenase 2 (IDH2) and fatty acid synthase (FAS) in breast cancer. The expression level of SIRT3 was downregulated while that of IDH2 and FAS was upregulated, which enhances the synthesis of fatty acids. Based on our previous findings, we hypothesize that: SIRT3 regulates IDH2 activity by deacetylation, which inhibits citric acid synthesis. Insufficient citric acid synthesis in turn blocks FAS-catalyzed fatty acid synthesis as well as the proliferation and metastasis of breast cancer. To test the hypothesis,we proposed a combined study from molecular, cellular and organ levels to investigate the role and mechanism of SIRT3/IDH2/FAS axis: 1) SIRT3 regulates IDH2 activity by deacetylation;2)SIRT3 overexpression and IDH2 silencing inhibit FAS-catalyzed fatty acid synthesis; and 3) The regulation of fatty acid synthesis through SIRT3/IDH2/FAS axis inhibits proliferation and metastasis of breast cancer in vitro and vivo. Multiple techniques including lentivirus-mediated gene transfection and silencing, co-immunoprecipitation, immunofluorescence combined with laser confocal microscopyt and tumorigenesis will be applied. Insights on novel treatment for breast cancers such as the theoretical basis and molecular targets of are expected from the proposed studies.

乳腺癌是女性发病率最高的恶性肿瘤，脂肪酸代谢重编程促进乳腺癌增殖转移，然调控机制未明。我们前期发现去乙酰化酶SIRT3、异柠檬酸脱氢酶2（IDH2）及脂肪酸合成酶（FAS）在乳腺癌异常表达，SIRT3低表达，IDH2与FAS表达且活性异常升高，促进脂肪酸合成。我们推测SIRT3/IDH2/FAS轴调控乳腺癌脂肪酸合成代谢重编程的机制：SIRT3去乙酰化修饰IDH2促进柠檬酸氧化，抑制柠檬酸合成，抑制FAS合成脂肪酸，从而抑制乳腺癌增殖转移。我们拟采用慢病毒介导基因转染与沉默、免疫共沉淀、免疫荧光-激光共聚焦和裸鼠成瘤等技术从分子、细胞和器官水平研究证实：1)乳腺癌SIRT3去乙酰化修饰IDH2；2) 过表达SIRT3与沉默IDH2抑制FAS合成脂肪酸；3）SIRT3/IDH2/FAS轴调控脂肪酸合成抑制乳腺癌增殖转移。本研究将为逆转脂肪酸合成代谢重编程从而抑制乳腺癌提供理论依据和分子靶点。

快速增殖的乳腺癌细胞重编程能量代谢与生物合成，脂肪酸代谢在癌症中的重要作用日益受到重视。Sirtuin3（SIRT3）定位于线粒体基质，是癌细胞FA代谢的重要调节因子。在我们的研究中，我们探讨了lncRNA跨膜磷酸酶与TPTEP1和SIRT3在三阴性乳腺癌（TNBC）FA代谢中的关系。通过Colony formation, wound healing and transwell assays实验，观察TPTEP1对TNBC细胞增殖、迁移和侵袭的影响。Westernblot分析TPTEP1对TNBC细胞上皮间质转化（EMT）相关蛋白和几种FA代谢酶水平的影响。几个力学实验检测了TNBC细胞中TPTEP1和SIRT3之间的调节机制。结果发现：TPTEP1在TNBC细胞中低表达。TPTEP1增加显著抑制TNBC细胞增殖、迁移、侵袭、EMT和FA代谢重编程。TPTEP1通过与miR-1343-3p竞争的内源性RNA（ceRNA）对SIRT3进行正调控，SIRT3对FOXO3a进行正调控，抑制TNBC细胞Wnt/β-catenin通路。因而，可以得出结论，TPTEP1通过miR-1343-3p/SIRT3/FOXO3a/Wnt/β-catenin信号通路调控TNBC的进展，为TNBC的治疗提供了新的靶点。本研究将为逆转乳腺癌代谢重编程从而抑制乳腺癌提供理论依据和分子靶点，为乳腺癌治疗提供新思维与新策略。项目投入经费37.0万元，支出36.935万元，各项支出基本与预算相符。剩余经费0.065万元，剩余经费计划用于本项目研究后续支出。

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