调控VEGF表达的新型转录因子的发现及其在肿瘤中的功能

The growth and metastasis of tumors depend on the formation of new blood vessels. The vascular endothelial growth factor (VEGF) plays an important role in the tumor growth, invasion and metastasis. Using the luciferase reporter system to screen for transcription factors regulating VEGF promoter activity, we identified HOMEZ as a novel regulatory factor. We further demonstrated that HOMEZ protein activated the activity of VEGF promoter in a dose-dependent manner. We also found that HOMEZ protein was recruited to the VEGF promoter, regulating the mRNA and protein expression of VEGF. Preliminary results showed that HOMEZ was up-regulated in breast cancer patients, and the expression HOMEZ was related to the expression of VEGF. These results suggest that HOMEZ protein may play crucial roles in the development and progression of tumor. Using different techniques such as reporter gene assay, real-time PCR, chromatin immunoprecipitation, gel shift assay, chorioallantoic membrane assay, scratch adhesion test, transwell assay, angiogenesis assay in vivo, and immunohistochemistry, we will try to figure out the role and molecular mechanism of HOMEZ protein in angiogenesis and the development and progression of tumor as well as its clinical significance, which will lay a strong foundation for elucidating the mechanism of invasion and metastasis and looking for new targets for tumor diagnosis and therapy.

肿瘤的生长和转移依赖于新生血管生成，血管表皮生长因子（VEGF）在肿瘤生长、侵袭和转移中发挥重要作用。我们利用荧光素酶报告基因系统获得了新的调控VEGF启动子活性的转录因子HOMEZ，并发现HOMEZ激活VEGF启动子的活性，HOMEZ通过募集在VEGF的启动子上，促进VEGF mRNA和蛋白水平的表达。初步结果表明，HOMEZ在肿瘤病人中过量表达，且与VEGF表达具有相关性。这些结果预示HOMEZ在肿瘤的发生发展中具有重要作用。我们将利用报告基因技术、实时定量PCR技术、染色质免疫沉淀实验、EMSA实验、划痕实验、Transwell实验、鸡胚绒毛尿囊膜技术、体内血管生成实验、免疫组织化学技术等确定HOMEZ在血管生成、肿瘤生长、侵袭和转移中的作用及其分子机制、以及HOMEZ蛋白在肿瘤细胞生长调节中的作用及其在临床上的意义，为阐明肿瘤侵袭和转移的机理、发现新的肿瘤治疗靶标打下坚实的基础。

肿瘤的发展和转移依赖于血管，肿瘤细胞通过血管的供应获得营养，同时血管也为肿瘤转移提供通道。VEGF是最重要的血管生长调节因子。在大多数情况下，内皮细胞本身不表达VEGF，而是在癌细胞中表达，分泌出来的VEGF刺激和促进内皮细胞的增殖和迁移，而内皮细胞的增殖和迁移是血管形成的先决条件。因此，VEGF是肿瘤治疗的重要靶标。在本课题中，我们发现HOMEZ是调控VEGF表达和血管形成的重要调节因子。HOMEZ通过激活VEGF表达促进血管内皮细胞（HUVEC）的生长、迁移和成管。染色质免疫共沉淀和凝胶阻滞实验（EMSA）发现HOMEZ结合在VEGF的ATNAT序列。HOMEZ在体内外调控血管的形成并促进肿瘤细胞生长。HOMEZ在乳腺癌病人中过表达，并与肿瘤病人的无病生存期和总生存期相关，可能是乳腺癌的独立预后指标，说明HOMEZ在乳腺癌中具有显著意义，可以成为新的治疗靶标。