Tumor hypoxia promotes acquired resistance to radiation through ferroptosis inhibition

项目2摘要 肿瘤缺氧，定义为肿瘤内低氧压，在大多数实体恶性肿瘤中是常见的，包括 肺癌和食道癌。肺癌和食道癌的治疗包括放射治疗(RT)；然而， 临床上，这些癌症对RT产生获得性耐药。获得性RT耐药的机制是 未知，但可能涉及一种称为铁下垂的细胞死亡，这是拟议的 获得性抵抗治疗和铁(ARTI)中心。项目2将对这一总体主题作出贡献 通过确定低氧是否导致铁下垂抵抗，从而促进对RT的获得性抵抗。 项目2将利用项目1中产生的肺癌和食道癌细胞系，这些细胞系缺乏 铁下垂抗性介体溶质载体家族成员11(SLC7A11)及其一个转录产物 因子：激活转录因子4(ATF4)。基因的转录，包括低氧相关基因，可能 放化疗期间肿瘤细胞内和肿瘤微环境细胞内的动态调节 食管腺癌的治疗(CRT)，这是项目3的重点。为了确定是否 RT诱导铁下垂需要氧气，肺癌和食道癌细胞将受到不同程度的 氧浓度和辐射敏感性、脂质过氧化(即铁下垂的驱动因素)和SLC7A11 将测量表情(目标1)。目标2将重点描述低氧驱动的机制 通过确定SLC7A11的表达是否依赖于获得性RT抵抗而产生铁下垂抵抗 RT过程中缺氧条件下ATF4的表达。此外，由于低氧诱导因子(HIF)已被证明 为了促进辐射抵抗，低氧诱导的HIF激活在获得性铁下垂抵抗中的作用将 被调查。验证通过高压氧治疗增强肿瘤氧合的假说 (HBOT)以及小分子HIF和ATF4抑制剂可以通过增强 小鼠铁性下垂、肺癌、食道癌移植瘤联合RT治疗 HBOT或HIF/ATF4抑制剂(目标3)。放疗后的肿瘤生长将通过每周无创监测 分子成像核心(MIC)的生物发光成像。此外，在MIC，体内的缺氧区 肿瘤将通过使用正电子发射断层扫描(PET)示踪剂进行实时监测 18F-氟氮霉素阿糖苷(Faza)。总体而言，铁性下垂和获得性RT的不同调节 在项目2中发现的肿瘤中氧合不良和氧合良好区域的耐药性将反复出现 通过以下方式加强和支持基础科学/机械项目1和临床前/转化项目3 帮助识别可能对RT产生获得性耐药的肿瘤区域，这可能有助于患者的选择 后续治疗。

Project 2 Summary Tumor hypoxia, defined as low intratumoral oxygen tension, is common to most solid malignancies, including lung and esophageal cancer. Lung and esophageal cancer treatments include radiation therapy (RT); however, clinically, these cancers develop acquired resistance to RT. The mechanisms of acquired resistance to RT are unknown but may involve a type of cell death called ferroptosis, which is the overarching theme of the proposed Acquired Resistance to Therapy and Iron (ARTI) Center. Project 2 will contribute to this overarching theme by determining whether hypoxia drives ferroptosis resistance, thereby promoting the acquired resistance to RT. Project 2 will utilize lung and esophageal cancer cell lines generated in Project 1 that are deficient in the ferroptosis resistance-mediator Solute Carrier Family 7 Member 11 (SLC7A11) and one of its transcription factors: activating transcription factor 4 (ATF4). The transcription of genes, including hypoxia-related genes, may be dynamically regulated within tumor cells and cells of the tumor microenvironment during chemoradiation therapy (CRT) of esophageal adenocarcinoma, which is a focus of Project 3. In order to determine whether oxygen is required for ferroptosis induction by RT, lung and esophageal cancer cells will be subjected to varying oxygen concentrations and radiosensitivity, lipid peroxidation (i.e., driver of ferroptosis), and SLC7A11 expression will be measured (Aim 1). Aim 2 will focus on the delineation of the mechanisms of hypoxia-driven ferroptosis resistance during acquired RT resistance by determining whether SLC7A11 expression is dependent on ATF4 under hypoxic conditions during RT. Furthermore, as hypoxia inducible factors (HIFs) have been shown to promote radioresistance, the effect of hypoxia-induced HIF activation in acquired resistance to ferroptosis will be investigated. To test the hypothesis that enhanced tumor oxygenation through hyperbaric oxygen treatment (HBOT) as well as small molecule HIF and ATF4 inhibitors can overcome acquired radioresistance by enhancing ferroptosis induction, lung tumor and esophageal tumor xenografts in mice will be treated with RT in combination with HBOT or HIF/ATF4inhibitors(Aim 3). Tumor growth after RT will be monitored with weekly noninvasive bioluminescence imaging at the Molecular Imaging Core (MIC). Furthermore, in the MIC, hypoxic regions within tumors will be monitored in real-time by performing positron emission tomography (PET) using the PET tracer 18F-Fluoroazomycin arabinoside (FAZA). Overall, the differential regulation of ferroptosis and acquired RT resistance by poorly oxygenated and well oxygenated areas in tumors discovered in Project 2 will iteratively strengthen and support the basic science/mechanistic Project 1 and the preclinical/translational Project 3 by helping identify tumor regions that may develop acquired resistance to RT that could aid in patient selection for subsequent treatments.