GROWTH PLATE RADIATION RESPONSE--MECHANISMS AND THERAPY

生长板辐射反应——机制和治疗

• 批准号: 2010096
• 负责人: RANDY N ROSIER
• 金额: $ 22.43万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-04-01 至 2001-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2010096
• 关键词: apoptosis; biological signal transduction; bone development; calcium; cell differentiation; cell proliferation; chickens; chondrocytes; cyclic AMP; fibroblast growth factor; gene expression; immunocytochemistry; in situ hybridization; laboratory rat; messenger RNA; parathyroid hormone related protein; pentoxifylline; protein kinase A; radiation resistance; radiation therapy; radiobiology; retinoate; tissue /cell culture; transforming growth factors; tumor necrosis factor alpha

Disturbance or arrest of bone growth has long been recognized as a complication of the treatment of childhood milignancies with radiotherapy. However. There has been almost no work on the molecular mechanism of this phenomenon in the growth plate. This lack of information constitutes a glaring gap in our knowledge about this serious clinical problem, and precludes development of any therapeutic strategies to ameliorate radiation-induced growth plate injury. In the present proposal we present preliminary data on possible mechanisms by which radiation may disrupt specific aspects of normal cytokine and growth factor function in growth plate cartilage. The long term goals of the research are (1) to understand the derangements of growth factor function which contribute to radiation-induced bone growth arrest, and (2) to translate this information to clinically applicable strategies using nontoxic pharmacologic agents to potentially ameliorate gorwth plate injury in children undergoing radiotherapy for malignancies. Preliminary data using chick and rat growth plate chondrocyte culture and in vivo models indicate a specific pattern of the cellular and molecular events following irradiation, among which are the selective suppression of TGFbeta and PTHrP, the major mitogens driving proliferation, and inappropriate expression of TNFalpha, which may lead to premature hypertrophy and apoptosis. The obliteration of the autocrine mitogenic stimulus and evidence of premature apoptosis are consistent with the observed histology. The specific aims of the proposed reserch include: (1A) use our chick chondrocyte in vitro model to initially characterize and determine the pattern of disruptio of 3 specific mitogenic growth factors (bFGF.TFGbeta.PTHrP), and the innappropriate activation of one key cytokine (TNFalpha) following irradiation. (1B) Use this initial study of avian chondrocytes to help guide our shift to study of a more levelvant mammalian in vitro model of radiation effects on devloping rodent chondrocytes, using pellet cultures which recapitulate the tissue arechitecture and differentiation cascade of normal rat growth plate. (2A) Identify the signaling mechanisms leading to growth factor and TNFalpha derangement, through investigation of radiation effects on 2 specific second messengers: cytosolic calcium and cAMP/protein kinase A, both of which appear to be involved in mitogen suppression and stimulation of apoptosis. (2B) In this in vitro model of radiation damage, we will study response modification using retinoic acid to: suppress cytosolic calcium, TNFalpha expression, and apoptosis; and to stimulate bFGF, TFGbeta, and chondrocyte proliferation. (2C) We will study pentoxifylline as an additinal response modifier to: decrease cytosolic calcium and TNFalpha expression; and to stimulate cAMP and proliferation. (3A) Correlate in vitro findings with findings in a rat in vivo model using tissue-based approaches such as immunocytochemistry and in situ hybridization to conform mechanisms of radiation injury to the physis, as well as new clinically aplicable therapeutic strategies.

长期以来，骨骼生长的紊乱或停滞一直被认为是一种 儿童恶性肿瘤治疗的并发症 放射治疗。 然而。 几乎没有任何相关工作 生长板中这种现象的分子机制。 这 信息的缺乏构成了我们知识中的明显差距 关于这个严重的临床问题，并阻止发展 任何改善辐射诱导生长的治疗策略 板损伤。 在本提案中，我们提供了初步数据 辐射可能破坏特定的机制 正常细胞因子和生长因子在生长过程中的功能 板状软骨。 研究的长期目标是（1） 了解生长因子功能的紊乱 有助于辐射引起的骨生长停滞，并且（2） 使用以下方法将此信息转化为临床适用的策略 无毒药物可能会改善生长 接受恶性肿瘤放射治疗的儿童的钢板损伤。 使用鸡和大鼠生长板软骨细胞的初步数据 培养和体内模型表明细胞的特定模式 和辐射后的分子事件，其中包括 选择性抑制主要有丝分裂原 TGFbeta 和 PTHrP 驱动增殖和 TNFα 的不适当表达， 这可能导致过早肥大和细胞凋亡。 这 自分泌有丝分裂刺激的消除和证据 过早凋亡与观察到的组织学一致。 拟议研究的具体目标包括：（1A）使用我们的 鸡软骨细胞体外模型初步表征和 确定 3 种特定有丝分裂生长的破坏模式 因素（bFGF.TFGbeta.PTHrP），以及不适当的激活 辐射后一种关键细胞因子（TNFα）的变化。 (1B) 使用 这项对禽类软骨细胞的初步研究有助于指导我们转向 更水平的哺乳动物体外辐射模型的研究 使用颗粒培养物对啮齿动物软骨细胞发育的影响 概括了组织的结构和分化 正常大鼠生长板的级联。 (2A) 识别信号 导致生长因子和 TNFα 紊乱的机制， 通过调查辐射对 2 个特定秒的影响 信使：胞质钙和 cAMP/蛋白激酶 A，两者 似乎参与有丝分裂原的抑制和刺激 细胞凋亡。 (2B) 在这个辐射损伤的体外模型中，我们 将研究使用视黄酸的反应修饰来： 胞质钙、TNFα 表达和细胞凋亡；并到 刺激 bFGF、TFGbeta 和软骨细胞增殖。 (2C) 我们 将研究己酮可可碱作为附加反应调节剂： 减少胞质钙和 TNFα 的表达；并到 刺激 cAMP 和增殖。 (3A) 关联体外研究结果 使用基于组织的方法在大鼠体内模型中得到的结果 例如免疫细胞化学和原位杂交以符合 辐射对身体的损伤机制，以及新的 临床适用的治疗策略。