Induction of MGMT as a Strategy for Chemoprevention

诱导 MGMT 作为化学预防策略

基本信息

批准号：
7483274
负责人：
KALKUNTE S SRIVENUGOPAL
金额：
$ 7.43万
依托单位：
TEXAS TECH UNIVERSITY HEALTH SCIS CENTER
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-08-10 至 2011-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7483274
关键词：
4-oxothiazolidine Accounting Alkylating Agents Alkylation Amino Acids Animals Antineoplastic Agents Antioxidants Attention Attenuated Automobile Driving Biological Assay Bone Marrow Bone Marrow Stem Cell Brain Cancer cell line Carboxylic Acids Carcinogens Carmustine Catabolism Cells Chemoprevention Chemoprotection Clinical Trials Colon Colon Carcinoma Curcumin Cysteine DNA DNA Damage DNA Repair DNA Repair Enzymes DNA biosynthesis DNA lesion DNA repair protein Data Drug resistance Elevation Enzymes Ethanol Exposure to Food Frequencies Genes Genetic Transcription Genome Genus Cola Glioma Glutathione Guanine Hematopoietic System Hematopoietic stem cells Hepatic Hepatic Tissue Human Hypoxanthine Phosphoribosyltransferase Immunohistochemistry Induced Mutation Kidney Lesion Link Literature Liver Lung MGMT gene Malignant Neoplasms Measures Meat Medicinal Plants Messenger RNA Mismatch Repair Mus Mutation Nitroso Compounds Normal tissue morphology O(6)-Methylguanine-DNA Methyltransferase O(6)-benzylguanine Oncogenic Perception Peripheral Blood Lymphocyte Pharmaceutical Preparations Phytochemical Pilot Projects Plants Play Poison Polymerase Prodrugs Proliferating Cell Nuclear Antigen Property Protein Biosynthesis Protein Overexpression Proteins Publishing Pyroglutamate Hydrolase Rate Reaction Regulator Genes Research Resistance Reverse Transcriptase Polymerase Chain Reaction Role Silymarin Specificity System T-Lymphocyte TP53 gene Therapeutic Thioguanine Thymine Tobacco Toxic Actions Toxic effect Transgenic Mice Translations Trees alkyl group animal tissue attenuation base beta catenin cancer prevention cooking cytotoxic glutathione S-transferase pi inhibitor/antagonist nimbidin novel pre-clinical repaired response suicidal temozolomide treatment duration tumor

项目摘要

DESCRIPTION (provided by applicant): Modulation of DNA repair enzymes, leading to facilitated elimination of carcinogenic lesions is likely to be a 6 novel and successful strategy for cancer prevention. MGMT (O6-methylguanine-DNA-methyltransferase), 6 which elicits a direct reversal of guanine-O6 alkylations, plays a central role in protecting the cellular genome from the mutagenic and toxic actions of endogenous, food-derived, environmental, and therapeutic alkylating carcinogens. A vast amount of epidemiological and research data on the reduction of spontaneous and induced tumors in MGMT transgenic mice, attenuation of Ras and p53 mutations in MGMT-proficient cells and the ongoing strategy of MGMT gene transduction into the bone marrow stem cells for achieving alkylator resistance suggest that MGMT is an excellent and rational target for chemoprevention and perhaps chemoprotection. The long-term objective of this pilot (R03) project is to explore the possibility of augmenting MGMT levels through a dietary approach in human normal tissues including the hematopoietic system using a non-toxic cysteine prodrug and antioxidant plant compounds. We have obtained strong evidence for a marked and reproducible increase of MGMT activity (up to 3-fold) in a variety of human cancer cell lines after exposure to a cysteine prodrug (L-2oxothiazolidine-4-carboxylic acid or OTC), and antioxidant compounds such as silymarin, curcumin and ethanol extracts of several medicinal plants. Increased levels of MGMT mRNA and increased rate of MGMT protein synthesis accounted for the enhanced DNA repair activity. OTC is a non-toxic compound, metabolized by the cellular enzyme, 5-oxoprolinase to generate cysteine, whose availability in turn, increases the intracellular GSH levels greatly. Our hypothesis, built on these observations is that OTC and selected phytochemicals will enhance MGMT expression in animal tissues and attenuate the toxicity of clinically used alkylating agents. The major objective of this 2-year pilot project is to establish the feasibility of chemoprevention and chemoprotection via MGMT in a preclinical setting through the following Specific Aims: 1) Quantitate alterations in MGMT expression in hepatic and non-hepatic tissues including the peripheral blood lymphocytes in mice after OTC and antioxidant (curcumin, silymarin, and nimbidin) administrations. 2) Characterize the effect OTC administration on the levels and extent of BCNU, and temozolomide-induced mutations and toxicity in mice. In Specific Aim 1, The DNA repair activity of MGMT, mRNA and protein levels in liver, lung, colon, brain, peripheral blood lymphocytes, and hepatic mRNA levels will be measured after chemopreventative treatments. The treatment duration required for sustained elevation of the repair protein will be assessed. Specific Aim 2 will investigate the mutation frequencies in the Hprt gene of splenic T-lymphocytes, parameters of hematological and overall toxicities induced by BCNU and temozolomide in animals pretreated with OTC. The study promises to pave way for clinical trials of MGMT-targeted chemopreventative strategies. Further, because GSH and GST-pi, likely to be induced, these approaches will provide multiple benefits.

描述（由申请人提供）：调节 DNA 修复酶，促进消除致癌病变，可能是一种新颖且成功的癌症预防策略。 MGMT（O6-甲基鸟嘌呤-DNA-甲基转移酶）6 可引发鸟嘌呤-O6 烷基化的直接逆转，在保护细胞基因组免受内源性、食品源性、环境性和治疗性烷基化的诱变和毒性作用方面发挥着核心作用致癌物质。大量流行病学和研究数据，涉及 MGMT 转基因小鼠自发性和诱导性肿瘤的减少、MGMT 熟练细胞中 Ras 和 p53 突变的减弱以及正在进行的将 MGMT 基因转导到骨髓干细胞以实现烷化剂抗性的策略表明 MGMT 是化学预防甚至化学保护的一个极好的且合理的目标。该试点 (R03) 项目的长期目标是探索使用无毒半胱氨酸前药和抗氧化植物化合物通过饮食方法提高人类正常组织（包括造血系统）中 MGMT 水平的可能性。我们获得了强有力的证据，证明在接触半胱氨酸前药（L-2oxothiazolidine-4-carbic Acid 或 OTC）和抗氧化剂后，多种人类癌细胞系的 MGMT 活性显着且可重复地增加（高达 3 倍）。水飞蓟素、姜黄素和多种药用植物的乙醇提取物等化合物。 MGMT mRNA 水平的增加和 MGMT 蛋白质合成速率的增加是 DNA 修复活性增强的原因。 OTC 是一种无毒化合物，由细胞酶 5-氧代脯氨酸酶代谢产生半胱氨酸，半胱氨酸的利用率反过来又大大提高细胞内 GSH 水平。基于这些观察结果，我们假设 OTC 和选定的植物化学物质将增强动物组织中 MGMT 的表达，并减弱临床使用的烷化剂的毒性。这个为期 2 年的试点项目的主要目标是通过以下具体目标，在临床前环境中建立通过 MGMT 进行化学预防和化学保护的可行性：1) 定量肝脏和非肝脏组织（包括外周血淋巴细胞）中 MGMT 表达的变化小鼠服用非处方药和抗氧化剂（姜黄素、水飞蓟素和宁比丁）后。 2) 表征 OTC 给药对 BCNU 水平和程度的影响，以及替莫唑胺诱导的小鼠突变和毒性。在具体目标1中，化学预防治疗后将测量MGMT的DNA修复活性、肝、肺、结肠、脑、外周血淋巴细胞中的mRNA和蛋白质水平以及肝mRNA水平。将评估修复蛋白持续升高所需的治疗持续时间。具体目标 2 将研究脾 T 淋巴细胞 Hprt 基因的突变频率、BCNU 和替莫唑胺在 OTC 预处理的动物中诱导的血液学参数和总体毒性。该研究有望为 MGMT 靶向化学预防策略的临床试验铺平道路。此外，由于 GSH 和 GST-pi 可能被诱导，这些方法将提供多种好处。