VEGF mRNA Expression Mechanisms in Hypoxia

描述（申请人提供）：低氧刺激促进肿瘤细胞存活、血管生成和乳腺癌侵袭。血管内皮生长因子（VEGF）的表达需要缺氧诱导的转录、mRNA稳定、mRNA穿梭、蛋白翻译和分泌。分泌的VEGF促进局部血管通透性和血管生成，从而促进肿瘤扩张和转移潜能。我们已经确定了两种促进缺氧依赖性VEGF表达的基本机制：1)通过双链rna结合蛋白DRBP76和ILF3转录后控制mRNA加工，以及2)amp激活的蛋白激酶a2 （AMPKa2）控制mRNA穿梭和翻译。该提案的中心主题是，在缺氧微环境中，肿瘤的进展需要AMPK信号通过转录后机制和生长因子信号通路的调节来表达VEGF和适应性细胞存活。缺氧诱导的AMPK还能抑制乳腺癌细胞中丝裂原活化蛋白激酶（MAPK）通路，提示全身AMPK激活可以抑制体内乳腺癌的增殖。这些假设将在以下目标中得到验证：Specific Aim 1将定义双链rna结合蛋白（DRBP76/ILF3）在缺氧诱导的VEGF mRNA稳定性、细胞内穿梭和翻译中的作用，以及在乳腺肿瘤进展、血管生成和转移实验模型中的生物学相关性。特异性目的2将研究AMPKa2亚型和AMPK信号通过转录后机制和抑制MAPK信号在乳腺癌细胞中控制DRBP/ILF3功能在缺氧诱导的VEGF表达中的作用。特异性am3将评估AMPKa2作为人类乳腺癌进展的中心调节因子的作用，内源性肿瘤发生的需求以及作为原发性和转移性乳腺癌的新型治疗干预的系统性AMPK激活的潜力。

DESCRIPTION (provided by applicant): Hypoxic stimuli promote tumor cell survival, angiogenesis and breast cancer invasion. The expression of vascular endothelial growth factor (VEGF) requires hypoxia-induced transcription, mRNA stability, mRNA shuttling, protein translation and secretion. Secreted VEGF promotes local vascular permeability and angiogenesis, thus promoting tumor expansion and metastatic potential. We have identified two essential mechanisms that contribute to hypoxia-dependent VEGF expression: 1) post-transcriptional control of mRNA processing by double-stranded RNA-binding proteins, DRBP76 and ILF3, and 2) AMP-activated protein kinase a2 (AMPKa2) control of mRNA shuttling and translation. The central theme for this proposal is that tumor progression in hypoxic microenvironments requires AMPK signaling for VEGF expression and adaptive cell survival via post-transcriptional mechanisms and modulation of growth factor signaling pathways. Hypoxia-induced AMPK also represses mitogen activated protein kinase (MAPK) pathways in breast cancer cells, suggesting that systemic AMPK activation could repress breast cancer proliferation in vivo. These hypotheses will be tested in the following aims: Specific Aim 1 will define the role of double stranded RNA-binding proteins (DRBP76/ILF3) in hypoxia-induced VEGF mRNA stability, intracellular shuttling and translation and for biological relevance in experimental models of breast tumor progression, angiogenesis and metastasis. Specific Aim 2 will investigate the role of AMPKa2 isoform and AMPK signaling in controlling DRBP/ILF3 function in hypoxia-induced VEGF expression via post-transcriptional mechanisms and repression of MAPK signaling in breast cancer cells. Specific Am 3 will assess the role of AMPKa2 as a central regulator of human breast cancer progression, requirement for endogenous tumorigenesis and the potential for systemic AMPK activation as a novel therapeutic intervention for primary and metastatic breast cancer.