Proteoglycan regulation of tumor angiogenesis and endothelial cell autophagy

女性死亡的主要原因是侵袭性乳腺癌的发生、发展和转移。的 肿瘤细胞和肿瘤微环境之间的双向交流， 氧气和营养素，是促进不受抑制的肿瘤发生发展，异常 新血管形成和广泛转移。因此，更好地理解嵌入式线索和可溶性 这两个部分之间交换的信息将证明是非常宝贵的， 癌症的病理生物学和可靠地预测临床结果。 我们的中心假设是内排斥素，一种多结构域硫酸乙酰肝素， 蛋白聚糖，利用双受体拮抗作用阻止内皮细胞参与肿瘤 血管生成这一工作假设是基于一个有影响力和有前途的工作机构，所有这些工作都是在 这一资助的赞助。我们发现：[a] Endorepelin同时连接，具有高亲和力， VEGFR 2和VEGFR 2 β 1整联蛋白，从而构成“双重受体拮抗作用”的分子基础。 这两种受体的参与强调了内排斥素在靶向中的灵敏度和特异性。 内皮细胞[b]内皮排斥素触发VEGFR 2和VEGFR 2 β 1整合素的共内化， SHP-1酪氨酸磷酸酶的活化和VEGFA信号传导的减弱。[c]内排斥素诱导 通过调节Beclin 1、LC 3和p62表达以Peg 3依赖性方式进行内皮细胞自噬， 处理和细胞定位。[d]Endorepelin引起能量传感器激酶的延长激活 AMPK，无论能量水平如何。事实上，这一规定被认为是非规范的AMPK 磷酸化发生在营养物富集的条件下。[e]AMPK β的下游，内排斥素引起 内皮细胞中的自噬通量在机制上与mTOR抑制剂Torin 1平行。这些引人注目 研究结果表明，延长和持续的自噬是一种新的机制， 促进血管抑制，独立于营养剥夺。基于这些发现，我们计划： [1]阐明endorepellin诱导内皮细胞应激、自噬和线粒体自噬的机制。 [2]揭示内排斥素诱导HAS 2自噬抑制的机制。 [3]生成新的肿瘤发生小鼠模型，以解释促自噬和抗血管生成程序 由内驱避素激活 这些协调一致的研究目标将使我们能够翻译我们的发现， 基质自噬模型，转化为临床相关范例。内排斥素诱导的 双重受体拮抗作用下游的内皮细胞自噬将导致新的治疗进展， 积极诱导肿瘤微环境中的自噬，以对抗这种毁灭性的疾病。

Chief among female mortality is the development, progression, and metastasis of aggressive breast cancer. The bidirectional communication between the neoplastic cells and the tumor microenvironment, which supplies oxygen and nutrients, is essential for promoting unchecked tumorigenic development, aberrant neovascularization, and widespread metastasis. Thus, a better understanding of embedded cues and soluble messages exchanged between these two compartments will prove invaluable for furthering our knowledge of the pathobiology of cancer and for reliably predicting clinical outcomes. Our central hypothesis is that endorepellin, a proteolytic fragment of perlecan, a multi-domain heparan sulfate proteoglycan, exploits a dual-receptor antagonism to preclude endothelial cells from participating in tumor angiogenesis. This working hypothesis is based on an impactful and promising body of work all generated under the auspices of this grant. We discovered that: [a] Endorepellin simultaneously ligates, with high affinity, VEGFR2 and the 21 integrin thereby constituting the molecular basis of “dual receptor antagonism”. Engagement of both receptors underscores the exquisite sensitivity and specificity of endorepellin in targeting the endothelia. [b] Endorepellin triggers co-internalization of VEGFR2 and 21 integrin with concurrent activation of the SHP-1 tyrosine phosphatase and attenuation of VEGFA signaling. [c] Endorepellin induces endothelial cell autophagy in a Peg3-dependent manner by modulating Beclin 1, LC3, and p62 expression, processing, and cellular localization. [d] Endorepellin evokes protracted activation of the energy-sensor kinase AMPK, irrespective of energy levels. Indeed, this regulation is considered non-canonical as AMPK phosphorylation occurred under nutrient-enriched conditions. [e] Downstream of AMPK, endorepellin evokes autophagic flux in endothelial cells that mechanistically parallels the mTOR inhibitor, Torin 1. These striking findings demonstrate that protracted and sustained autophagy is a novel mechanism by which endorepellin promotes angiostasis, independent of nutrient deprivation. Based on these discoveries, we plan to: [1] Elucidate the mechanism of endorepellin-evoked endothelial cell stress, autophagy and mitophagy. [2] Unravel the mechanism by which endorepellin induces autophagic suppression of HAS2. [3] Generate novel mouse models of tumorigenesis to explain the pro-autophagic and anti-angiogenic programs activated by endorepellin. These concerted research aims will enable us to translate our findings, procured with highly innovative mouse models of stromal autophagy, into clinically relevant paradigms. The discovery of endorepellin-induced endothelial cell autophagy downstream of dual receptor antagonism will lead to new therapeutic advances that actively induce autophagy within the tumor microenvironment to combat this devastating disease.