缺氧状态Foxp1通过Hif1α-Hk2通路抑制血管新生阻止肿瘤生长的机制研究

Angiogenesis plays an important role in the occurrence and development of tumor, and the hypoxic state during tumor growth results in glycolysis of endothelial cells, which regulates angiogenesis in tumor. Transcription factor Foxp1 is highly expressed in vascular endothelial cells ,Our previous studies demonstrated that angiogenesis in Lewis tumor cell line LLC xenographic tumor was significantly increased in endothelial specific Foxp1 deletion mice, accompanied with aggravated tumor growth, compared with that of littermate control wild-type mice. Endothelial deletion of Foxp1 neonatal mice exhibited enhanced retinal angiogenesis under hypoxia. The data mining of Foxp1 ChIP-seq database (Chromatin Immunoprecipitation sequence) suggests HIF1α as direct downstream target gene of Foxp1. It was reported that HIF1α regulates the expression of hexokinase HK2, a rate-limiting enzyme of glucose metabolism. Therefore, we perform ChIP and promoter luciferase reporter assay to confirm the regulation of Foxp1 for HIF1α and HIF1α for HK2. Moreover, we observe whether in vivo delete or in vitro knockdown HIF1α or HK2 reverses endothelial Foxp1 deletion mediated enhanced angiogenesis. Finally we use endothelial Foxp1 overexpression mice, as well as statin for elevated endothelial Foxp1 through its strong induction of Klf2 for treatment of angiogenesis overgrowth during tumor occurrence and development. This study advances our understanding of mechanisms of endothelial Foxp1 in tumor angiogenesis and growth, meanwhile also provide a novel target of angiogenesis as future therapeutic intervention for tumor growth.

血管新生对肿瘤发生发展起重要作用，肿瘤生长缺氧状态时内皮细胞通过糖酵解调节血管新生。血管内皮细胞高表达转录因子Foxp1，我们前期研究发现血管内皮Foxp1敲除鼠Lewis肿瘤细胞株LLC异种移植肿瘤血管新生显著增加，肿瘤生长加快；Foxp1敲除乳鼠缺氧状态下视网膜血管新生增加。ChIP-seq数据库挖掘提示缺氧诱导因子Hif1α是Foxp1靶基因，文献报道Hif1α调控糖代谢限速酶己糖激酶Hk2表达，因此我们拟通过ChIP和启动子荧光素报告系统证实Foxp1调控Hif1α以及Hif1α调控Hk2。同时，我们将在体内和体外分别干扰沉默Hif1α和Hk2基因观察是否可以逆转内皮Foxp1缺失造成的肿瘤血管新生增加。最后，使用内皮Foxp1过表达小鼠或药物他汀上调内皮细胞Foxp1治疗肿瘤发生发展过程中血管过度生长，为今后干预肿瘤生长提供新靶点。

血管新生对肿瘤发生发展起重要作用，肿瘤生长缺氧状态时内皮细胞通过糖酵解调节血管新生。血管内皮细胞高表达转录因子Foxp1，本项目研究发现血管内皮Foxp1敲除鼠Lewis肿瘤细胞株LLC异种移植肿瘤血管新生显著增加，肿瘤生长加快;Foxp1敲除乳鼠缺氧状态下视网膜血管新生增加。ChIP-seq数据库挖掘并多方验证缺氧诱导因Hif1a是Foxp1靶基因，Hk2是Hif1a靶基因，同时，体内和体外分别干扰沉默Hif1α和Hk2基因均可以逆转内皮Foxp1缺失造成的肿瘤血管新生增加。最后，使用内皮Foxp1过表达小鼠或药物他汀上调内皮细胞Foxp1治疗肿瘤发生发展过程中血管过度生长，为今后干预肿瘤生长提供新靶点，也为他汀类药物非降脂的多效性作用提供新的依据，同时也为临床开展他汀防治血管新生相关治疗提供理论依据。上述成果均具备很好的转化及应用基础和意义。