Project 2: ALDH3A1 Activation for Radioprotection of Salivary Glands and Other Head and Neck Epithelial Tissues

项目摘要（项目2） 唾液分泌减少或口干是头颈部肿瘤放射治疗最常见的并发症 （HNC）。它对患者的生活质量产生不利影响，并使他们面临重大晚期发病率的风险。电流 减轻唾液分泌不足的策略是昂贵且无效的。调强放射治疗（IMRT）， 旨在保留一个腮腺，导致刺激唾液功能的改善，但它不能保留 颌下腺，这是至关重要的休息唾液功能，因为他们的位置， 邻近引流淋巴结。我们和其他人发现，唾液干/祖细胞（SSPCs） 将约200个这些细胞注射到照射过的小鼠下颌下腺（SMG）中， 可以恢复唾液功能我们还发现ALDH 3A 1在SSPC中表达上调， 在RT之前、期间和之后用小分子活化剂活化这种酶， 增加的SSPC产量和RT后唾液功能的保存。 ALDH 3A 1增强RT后醛的清除，导致较少的SSPC凋亡，从而导致功能性 保存。在异种移植模型中，ALHD 3A 1激活剂的使用不能保护HNC免受辐射细胞杀伤 该酶的高表达不影响放化疗患者的预后。我们 已经从植物提取物中进行了筛选，并鉴定了一种天然产物d-柠檬烯，这证明 是ALDH 3A 1的高选择性激活剂。RT之前、期间和之后口服d-柠檬烯 导致RT后小鼠唾液功能的保存，但不能保护HNC细胞免受RT细胞杀伤。最 重要的是，已经研究了d-柠檬烯作为癌症的化学预防剂和抗癌疗法 患者并发现耐受性良好。由于其良好的安全性，d-柠檬烯是一种有前途的临床应用。 临床翻译候选人。 基于这些数据，本建议的主要目标是：（1）确定最大耐受量 在I期剂量递增试验中，在接受HNC放化疗的患者中使用d-柠檬烯剂量， 获得药物对唾液产生和患者生活质量影响的初步数据，（2）确定 在RT缺乏的情况下ALDH 3A 1的激活导致SSPC自我更新增加的机制，（3） 评估d-柠檬烯和/或C5 aR 1抑制对其他上皮组织的辐射防护作用，包括 皮肤、口腔粘膜和食管粘膜。我们的最终目标是测试是否ALDH 3A 1激活与 d-柠檬烯可以减轻HNC患者中RT诱导的口干症，并开发新的方法， 保护正常组织免受头颈部和胸部照射。

Project Abstract (Project 2) Hyposalivation or dry mouth is the most common complication of radiotherapy (RT) in head and neck cancer (HNC). It adversely impacts patients’ quality of life and places them at risk for significant late morbidities. Current strategies to mitigate hyposalivation are costly and ineffective. Intensity modulated radiotherapy (IMRT), which aims to spare one parotid gland, has resulted in improved stimulatory salivary function, but it cannot spare the submandibular glands, which are crucial for resting salivary function throughout the day, because of their location adjacent to the draining lymph nodes. We and others have found that salivary stem/progenitor cells (SSPCs) exist in adult glands and that injection of ~200 of these cells into irradiated murine submandibular glands (SMG) could restore saliva function. We have also found that ALDH3A1 expression is upregulated in SSPCs, and that activation of this enzyme with a small molecular activator before, during and after RT resulted increased SSPC yield and preservation of saliva function after RT. Mechanistically activation of ALDH3A1 enhanced clearance of aldehyde after RT, leading less SSPC apoptosis, resulting in functional preservation. The use of ALHD3A1 activator did not protect HNC from radiation cell kill in a xenograft model and high expression of this enzyme did not affect the prognosis of patients treated with chemoradiation. We have performed a screen from plant extracts and identified a natural product, d-limonene, which proves to be a highly selective activator of ALDH3A1. Oral administration of d-limonene before, during and after RT resulted in preservation of saliva function in mice after RT, but did not protect HNC cells from RT cell kill. Most importantly, d-limonene has been studied as a chemoprevention agent and an anti-cancer therapy in cancer patients and found to be well tolerated. Because of its favorable safety profile, d-limonene is a promising clinical candidate for clinical translation. Based on these data from, the main objectives of this proposal are: (1) To determine the maximum tolerated dose of d-limonene in patients undergoing chemoradiation for HNC in a phase I dose escalation trial and to obtain preliminary data on the effect of the drug on saliva production and patient quality of life, (2) To identify the mechanism by which activation of ALDH3A1 in the absence of RT leads to increased SSPC self-renewal, (3) To assess the effect of d-limonene and/or C5aR1 inhibition on radioprotection of other epithelial tissues including skin, oral mucosa and esophageal mucosa. Our ultimate goals are to test whether ALDH3A1 activation with d-limonene can mitigate RT-induced xerostomia in HNC patients and to develop novel approaches to protect normal tissues from head and neck and thoracic irradiation.