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，全国范围内有174,470例新病例和162,460例死亡。肺癌是最致命的恶性肿瘤之一，每年在全球范围内导致多达300万人死亡。放疗联合化疗是大多数晚期疾病患者的首选治疗方法。然而，由于辐射导致肺部毒性的风险，他们中只有一小部分人可以接受高剂量辐射。氨磷汀作为FDA批准的唯一放射保护剂，不能保护肺部，本身就会产生很大的毒性。因此，迫切需要开发改进的辐射防护器。我们有了重要的发现。首先，辐射增加了导致小鼠肺损伤的肺肿瘤坏死因子-α和转化生长因子-β1的产生。通过反义寡核苷酸(ASO)或基因敲除减少小鼠肺肿瘤坏死因子受体1(TNFR1)的表达，除了通过抑制转化生长因子-β1的活性来保护外，还通过减少肺细胞凋亡和改善肺功能而起到辐射防护作用。我们推测，联合使用肿瘤坏死因子-α和转化生长因子-β1靶向治疗可能会改善肺部的辐射防护。该应用的目的是了解肿瘤坏死因子-α和转化生长因子-β1及其受体在放射性肺毒性中的作用，并开发作为辐射保护剂的治疗性阻滞剂。在具体目标1中，我们将在一个小鼠模型中研究细胞因子及其受体在放射性肺毒性中的作用，如纤维化和肺功能下降。TNFR1和Smad3基因敲除小鼠将被用于验证辐射防护策略。在具体目标2中，我们将优化ASO在小鼠肺中特异性抑制TNFR1和Smad3通路的使用，作为单次剂量和分次辐射的保护者。在具体目标3中，我们将进行治疗性实验，以评估联合使用TNFR1和Smad3抑制对小鼠肺癌异种移植模型的辐射防护的潜在益处。治疗效果将通过评估正常的肺保护和肿瘤对辐射的敏感性来确定。这些研究将对辐射引起的肺组织损伤的机制提供见解，从而导致改进的辐射防护剂的开发。 公共卫生相关性： 放射性所致的正常肺损伤极大地限制了包括肺癌在内的胸部肿瘤的放射治疗效果。尽管已知辐射过程中细胞因子转化生长因子-β1的作用可引起肺毒性，但阻断这一作用并不完全具有辐射防护作用，因为其他机制也可能参与其中。在这一应用中，我们建议通过使用特定的反义寡核苷酸来阻断转化生长因子-β1和肿瘤坏死因子-α的作用，这是我们先前证明在放射性肺毒性中起关键作用的途径，以实现更好的肺放射防护。

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.