Role of elF2a phosphorylation and ER stress in hypoxia tolerance and tumor growth

eF2a磷酸化和内质网应激在缺氧耐受和肿瘤生长中的作用

• 批准号: 7625243
• 负责人: Constantinos Koumenis
• 金额: $ 25.75万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7625243
• 关键词: Acute; Address; Animals; Anoxia; Apoptosis; Apoptotic; Area; Biological Assay; Cell Hypoxia; Cell Survival; Cells; Chemotherapy-Oncologic Procedure; Chronic; Clinical; Dependency; Development; Down-Regulation; Endoplasmic Reticulum; Environment; Enzymes; Event; Funding; Gene Expression Microarray Analysis; Grant; Human; Hypoxia; In Vitro; Ionizing radiation; Malignant - descriptor; Malignant neoplasm of prostate; Mass Spectrum Analysis; Mediating; Membrane; Modality; Modeling; Modification; Morbidity - disease rate; Mus; Mutation; Nature; Neoplasm Metastasis; Nude Mice; Outcome; Oxidants; Oxidases; Oxygen; Oxygen measurement, partial pressure, arterial; PERK kinase; Pathway interactions; Patients; Peptide Initiation Factors; Phosphorylation; Play; Process; Protein Biosynthesis; Protein Disulfide Isomerase; Proteins; Public Health; RNA Interference; Radiation therapy; Reliance; Reporting; Research Personnel; Resistance; Role; Sampling; Signal Transduction; Solid Neoplasm; Stress; Stress Tests; Testing; Thapsigargin; Therapeutic; Time; Transgenic Model; Translating; Tumor Cell Line; Up-Regulation; Velcade; Xenograft procedure; biological adaptation to stress; cell transformation; chemotherapeutic agent; chemotherapy; cytotoxic; disulfide bond; endoplasmic reticulum stress; improved; in vivo; killings; neoplastic cell; novel; outcome forecast; overexpression; programs; protein folding; research study; response; stressor; therapeutic target; therapy resistant; transcription factor; tumor; tumor growth; tumor xenograft; tumorigenesis

DESCRIPTION (provided by applicant): Hypoxia is a well-characterized component of the solid tumor microenvironment that promotes resistance to radiation therapy and chemotherapy and is associated with a poorer overall prognosis. The hypoxic tumor cell elicits both HIF-dependent and HIF-independent mechanisms to adapt to and overcome the stress of low oxygen in tumors. Through experiments performed under the specific aims of the previously funded application and preliminary results in this proposal, we have shown that hypoxia/anoxia rapidly activates a translational control program mediated by activation of the endoplasmic reticulum (ER) kinase PERK and phosphorylation of the translation initiation factor elF2?. This pathway downregulates global protein synthesis but at the same time upregulates the expression of select stress-response proteins. These results together with those from other groups established that the Unfolded Protein Response, a cellular adaptation mechanism to ER stress, is activated by hypoxia and is required for hypoxia tolerance and tumor growth. In this application we propose to expand these findings to identify the signal for UPR activation by hypoxia, identify the role(s) of downstream effectors of PERK and elF2? phosphorylation, characterize pro- and anti- apoptotic pathways activated by ER stress and test whether the reliance of hypoxic tumor cells on UPR activation for survival can be therapeutically exploited. In Specific Aim 1 we will test whether lack of the downstream PERK effector ATF4 expression inhibits, and overexpression of ATF4 promotes, tumor growth and we will identify and characterize transcriptional targets of hypoxia-activated ATF4. Under Specific Aim 2 we will attempt to delineate the mechanism responsible for PERK and UPR activation under hypoxia by analyzing the status of-SH groups on the ER-resident folding enzymes Protein Disulfide Isomerase, and Erolp oxidase. In Specific Aim 3 we will investigate the role(s) of ER-targeted bcl-2 and ER-localized bax/bak in the induction of ER-dependent apoptosis by hypoxia/anoxia in UPR-proficient and -deficient cells. Under Specific Aim 4 we will test whether hypoxic tumor cells, which are resistant to genotoxic chemotherapeutic agents, are acutely sensitive to pharmacological ER stressors and whether the combination of ER stressors with ionizing radiation or chemotherapeutic agents results in better inhibition of tumor growth in animal tumor models. Solid tumor metastasis and resistance to most established chemotherapy regimens are key contributors to tumor morbidity and thus constitute a significant public health problem. Successful completion of the proposed studies will uncover a novel pathway that contributes to tumorigenesis and resistance to therapy and can potentially offer new targets and approaches to selectively attack these resistant cells and thus improve therapeutic outcome.

描述(申请人提供)：缺氧是实体肿瘤微环境的一种特征良好的成分，它促进对放射治疗和化疗的抵抗，并与较差的整体预后相关。低氧肿瘤细胞诱导HIF依赖和非HIF依赖的机制来适应和克服肿瘤中的低氧应激。通过在先前资助的申请的特定目标下进行的实验和在该提案中的初步结果，我们已经表明，低氧/缺氧通过激活内质网(ER)激酶PERK和翻译起始因子elF2？的磷酸化而迅速激活翻译控制程序。这一途径下调了全球蛋白质的合成，但同时上调了部分应激反应蛋白的表达。这些结果与其他组的结果一起证实，未折叠蛋白反应是一种对内质网应激的细胞适应机制，由缺氧激活，是耐缺氧和肿瘤生长所必需的。在这一应用中，我们建议扩展这些发现，以确定低氧激活UPR的信号，确定PERK和elF2下游效应因子的作用(S)。本研究的目的是研究细胞内信号转导蛋白的磷酸化，鉴定内质网应激激活的促凋亡和抗凋亡通路，并测试低氧肿瘤细胞对UPR激活生存的依赖是否可以用于治疗。在特定的目标1中，我们将测试下游PERK效应器ATF4的缺乏是否抑制肿瘤的生长，以及ATF4的过表达是否促进肿瘤的生长，我们将鉴定和鉴定缺氧激活的ATF4的转录靶点。在特定目标2下，我们将试图通过分析内质网驻留的折叠酶、蛋白质二硫键异构酶和EROROP氧化酶上的-SH基团的状态来描述缺氧条件下PERK和UPR激活的机制。在具体目标3中，我们将研究ER靶向的bcl2和ER定位的bax/bak在缺氧/缺氧诱导UPR熟练和缺陷细胞内ER依赖的细胞凋亡中的作用(S)。在特定目标4下，我们将测试耐受遗传毒性化疗药物的低氧肿瘤细胞是否对药物内质网应激源敏感，以及内质网应激源与电离辐射或化疗药物相结合是否能更好地抑制动物肿瘤模型中的肿瘤生长。实体肿瘤转移和对大多数已建立的化疗方案的耐药性是肿瘤发病率的关键因素，因此构成了一个重大的公共卫生问题。拟议研究的成功完成将揭示一条有助于肿瘤发生和治疗耐药的新途径，并可能提供有选择地攻击这些耐药细胞的新靶点和方法，从而改善治疗结果。