Lung radioprotection by inhibition of TNF-alpha and TGF-beta1

描述（由申请人提供）： 2006年，美国癌症协会估计全国有174，470例肺癌新发病例和162，460例肺癌死亡，肺癌是最致命的恶性肿瘤之一，每年在全世界造成多达300万人死亡。放疗联合化疗是大多数晚期疾病患者的治疗选择。然而，由于辐射引起的肺毒性风险，只有少数人可以接受高剂量辐射。氨磷汀作为唯一FDA批准的放射防护剂，本身不保护肺，并产生大量毒性。因此，迫切需要开发改进的辐射防护剂。我们取得了重要的发现。首先，辐射增加了导致小鼠肺损伤的肺TNF-α和TGF-β 1的产生。通过反义寡核苷酸（阿索）或基因敲除降低小鼠肺TNF受体1（TNFR 1），除了通过抑制TGF-β 1活性来保护外，还通过减少肺细胞凋亡和改善肺功能来保护辐射。我们假设联合TNF-α和TGF-β 1靶向治疗可能会改善肺的放射防护作用。本申请的目的是了解TNF-α和TGF-β 1及其受体在辐射诱导的肺毒性中的作用，并开发作为辐射防护剂的治疗性阻断剂。在具体目标1中，我们将研究细胞因子及其受体在辐射诱导的肺毒性中的作用，如小鼠模型中的纤维化和肺功能降低。TNFR 1和Smad 3的敲除小鼠将用于验证辐射防护策略。在特定目标2中，我们将优化阿索的使用，用于特异性抑制小鼠肺中的TNFR 1和Smad 3通路，作为对单次剂量和分次辐射的保护剂。在具体目标3中，我们将进行治疗实验，以评估TNFR 1和smad 3抑制剂联合用于小鼠肺癌异种移植模型中的辐射防护的潜在益处。治疗效果将通过评估正常肺保护和肿瘤对放射的敏感性来确定。这些研究将提供有关辐射诱导的肺组织损伤机制的见解，从而导致改进的辐射防护剂的开发。 公共卫生相关性： 放射性肺损伤严重限制了包括肺癌在内的胸部肿瘤的放射治疗效果。尽管已知细胞因子TGF-β 1在辐射期间的作用会诱导肺毒性，但阻断该作用并不完全具有辐射防护作用，因为还可能涉及其他机制。在本申请中，我们建议阻断TGF-β 1和TNF-α的作用，这是我们以前证明在辐射肺毒性中至关重要的途径，通过使用特定的反义寡核苷酸来实现改善的肺辐射保护。

DESCRIPTION (provided by applicant): In 2006, the American Cancer Society estimates a nationwide 174,470 new cases and 162,460 deaths from lung cancer, one of the most deadly malignancies that kills up to 3 millions annually worldwide. Radiation combined with chemotherapy is the treatment of choice for most patients with advanced disease. However, only a minority of them can receive high-dose radiation due to the risk of radiation-induced lung toxicity. Amifostine as the only FDA-approved radioprotector does not protect the lung and produces substantial toxicity by itself. Therefore, there is an urgent need for developing improved radioprotectors. We have made important findings. First, radiation increases lung TNF-alpha and TGF-beta1 productions that cause lung damage in mice. Reduction of lung TNF receptor 1 (TNFR1) by antisense oligonucleotide (ASO) or by genetic knock-out in mice is radioprotective by decreasing lung apoptosis and improving pulmonary function, in addition to the protection by inhibiting TGF-beta 1 activity. We hypothesize that combined TNF-alpha and TGF-beta1 targeted therapy may provide an improved radioprotection in the lung. The goals of this application are to understand the roles of TNF-alpha and TGF-beta1 and their receptors in radiation-induced lung toxicity and to develop therapeutic blocking agents as radioprotectors. In Specific Aim 1, we will study the roles of both cytokines and their receptors in radiation-induced lung toxicity such as fibrosis and reduced lung function in a mouse model. Knock-out mice for TNFR1 and Smad3 will be used to validate the radioprotection strategy. In Specific Aim 2, we will optimize the use of ASO for specific inhibition of TNFR1 and Smad3 pathways in mouse lung as protectors against a single dose and fractionated radiation. In Specific Aim 3, we will conduct therapeutic experiments to assess the potential benefit of combining TNFR1 and smad3 inhibition for protection against radiation in mice lung cancer xenograft model. Therapeutic effect will be determined by evaluating both normal lung protection and tumor sensitivity to radiation. These studies will provide insights on the mechanisms of radiation-induced lung tissue damage, leading to the development of improved radioprotectors. PUBLIC HEALTH RELEVANCE: Radiation-caused normal lung damage greatly limits the treatment effect of radiotherapy for thoracic cancers including lung cancer. Although the action of cytokine TGF-beta1 during radiation has been known to induce lung toxicity, blocking this action is not completely radioprotective because other mechanisms may also be involved. In this application, we propose to block actions for both TGF-beta1 and TNF-alpha, a pathway that we previously demonstrated be crucial in radiation lung toxicity, by using specific antisense oligonucleotides to achieve improved lung radioprotection.