Mechanisms for GH action on epithelial cells

项目摘要 垂体生长激素（GH）分泌到循环中，GH也在局部组织中表达， 在那里它引发自分泌/旁分泌信号。生长激素发挥多种作用，包括骨骼和纵向 生长，以及维持身体和组织质量以及代谢稳态。GH行动是直接的，或 可能是由IGF 1介导的。GH信号传导缺陷与癌症发展减少有关，而在 相反，GH过量（例如，源于肢端肥大症的垂体腺瘤）导致软组织过度生长 增加软组织息肉和腺瘤以及结肠癌的风险。局部结肠基质GH也是 在DNA损伤后。我们现在提出几条初步证据，表明垂体源性和 局部GH既能抑制结肠粘膜p53，又能减少细胞凋亡。这些促增殖生长激素的作用导致 与APC下调、细胞核β-连环蛋白积累以及细胞凋亡增加有关。 MMP和EMT因子。与这些发现一致，当我们用GH受体抑制GH信号时， 阻断剂，并进行结肠活检肢端肥大症患者，我们观察诱导结肠粘膜p53， APC，从而逆转促生长GH信号。我们在这里提出，生长激素是一个分子组成部分， 允许肿瘤生长的正常上皮粘膜“区域变化”环境。 在具体目标I中，使用正常人结肠细胞和iPSC衍生的人骨髓基质细胞的新型3-D模型， 肠道肠道芯片微流控装置，我们将阐明生长激素对粘膜变化的影响，发生在 肿瘤发展的肿瘤前阶段，并阐明GH相关p53的机制 镇压在特定目标II中，我们将使用GH过量的小鼠模型来确定 体内结肠粘膜。我们将把遗传上易患结肠肿瘤的小鼠与缺乏 GH信号传导，以确认结肠肿瘤发展的GH需求。具体目标一和二， 肠肠道芯片装置和动物模型，我们将描绘直接从IGF 1介导的GH的影响， 对结肠上皮细胞的影响在具体目标III中，我们将研究GH对DNA损伤的旁分泌作用， 染色体不稳定性，以及对结肠上皮粘膜的后续影响。 通过阐明p53介导的GH调节作用的新机制，我们将提供生物学和 临床证据支持生长激素过量使上皮肿瘤生长的假设，如遇到 肢端肥大症考虑到肢端肥大症的多种软组织共病，这些实验提供了 GH引起的有害上皮损伤的发病机制的机制见解。

PROJECT SUMMARY Pituitary growth hormone (GH) is secreted to the circulation and GH is also expressed in local tissues, where it elicits autocrine/paracrine signaling. GH exerts multiple actions including skeletal and longitudinal growth, as well as maintenance of body and tissue mass and metabolic homeostasis. GH actions are direct, or may be mediated by IGF1. Deficient GH signaling is associated with decreased cancer development, while in contrast, GH excess (e.g., derived from a pituitary adenoma in acromegaly) results in soft tissue overgrowth and increased soft tissue polyps and adenomas, and risk of colon carcinoma. Local colon stromal GH is also induced after DNA damage. We now present several lines of preliminary evidence that pituitary-derived and local GH both act to suppress colon mucosal p53 and reduce apoptosis. These pro-proliferative GH effects lead to increased cell survival with downregulated APC, accumulation of nuclear β-catenin, as well as increased MMPs and EMT factors. Consistent with these findings, when we suppressed GH signaling with a GH receptor blocker and performed colon biopsies in acromegaly patients, we observed induced colon mucosal p53 and APC, thereby reversing pro-growth GH signals. We propose here that GH is a molecular component of the normal epithelial mucosa “field change” milieu permissive for neoplastic growth. In Specific Aim I, using normal human colon cells and a novel 3-D model of iPSC-derived human intestinal gut-on-a-chip microfluidic devices, we will elucidate GH effects on mucosal changes that occur in pre-neoplastic stages of tumor development and also elucidate mechanisms underlying GH-associated p53 suppression. In Specific Aim II, we will use mouse models of GH excess to determine temporal changes in colon mucosa in vivo. We will crossbreed mice genetically predisposed to colon tumors with mice deficient in GH signaling to confirm GH requirements for colon neoplasia development. In Specific Aims I and II using intestinal gut-on-a-chip devices and animal models, we will delineate direct from IGF1-mediated effects of GH on colon epithelial cells. In Specific Aim III, we will examine paracrine actions of GH on DNA damage and chromosomal instability, as well as subsequent effects on colon epithelial mucosa. By elucidating novel p53-mediated mechanisms for GH regulatory actions, we will provide biological and clinical evidence to support the hypothesis that GH excess enables epithelial neoplastic growth, as encountered in acromegaly. Given the multiple soft tissue co-morbidities of acromegaly, these experiments offer mechanistic insights into pathogenesis of deleterious epithelial damage engendered by GH.