Pharmacogenetics of Ara-C Metabolic Pathway

Ara-C 代谢途径的药物遗传学

• 批准号: 7911312
• 负责人: Jatinder K. Lamba
• 金额: $ 9.2万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7911312
• 关键词: 5' -Nucleotidase; Abbreviations; Acute Myelocytic Leukemia; Adverse reactions; Affect; African; Aftercare; Ara-C; Arabinofuranosylcytosine Triphosphate; Binding Sites; Biological Assay; Blast Cell; Candidate Disease Gene; Cell Line; Cells; Childhood Acute Myeloid Leukemia; Childhood Leukemia; Clinical; Clinical Protocols; Clofarabine; Code; Collaborations; Cytarabine; DCMP Deaminase; DNA; DNA Synthesis Inhibition; Data; Decitabine; Deoxycytidine Kinase; Development; Diagnostic; Disease remission; Disease-Free Survival; Dose; Drug toxicity; Drug usage; EMSA; Electrophoretic Mobility Shift Assay; Enrollment; Enzymes; European; Evaluation; Financial Support; Frequencies; Future; Gene Expression; Genes; Genetic; Genetic Code; Genetic Polymorphism; Genetic Variation; Genomics; Genotype; Goals; Government; Human; In Vitro; Individual; Inherited; International; Introns; Leukemic Cell; Luciferases; Malignant Childhood Neoplasm; Measurement; Metabolic; Metabolic Pathway; Metabolism; Molecular; Nigeria; Nucleic Acid Regulatory Sequences; Nucleoside Transporter; Outcome; Pathway interactions; Patients; Persons; Pharmacogenetics; Pharmacogenomics; Phenotype; Predisposition; Prodrugs; Protocols documentation; Reaction; Relative (related person); Reporter; Reporting; Research; Research Personnel; Resistance; Ribonucleotide Reductase; Risk; Saint Jude Children' s Research Hospital; Sampling; Series; Single Nucleotide Polymorphism; Testing; Toxic effect; Treatment outcome; Variant; base; chemotherapy; clinical phenotype; deoxycytidine deaminase; enzyme activity; ethnic difference; experience; gemcitabine; genetic profiling; genetic variant; genome-wide; improved; in vivo; lymphoblast; lymphoblastoid cell line; mRNA Expression; nucleoside analog; outcome forecast; promoter; research study; response; transcription factor; treatment response; uptake

DESCRIPTION (provided by applicant): The nucleoside analog cytarabine (ara-C) has been the mainstay of acute myeloid leukemia (AML) chemotherapy for more than 40 years and is one of the most important drugs used to induce remission in patients with AML. A number of studies suggest that the intracellular concentration of its active metabolite, ara-CTP, varies widely among patients and in turn is associated with variability in clinical response. The objective of the current proposal is to determine the molecular basis of this variation in intracellular ara-CTP levels by identifying and evaluating the pharmacogenomic effect of genetic polymorphisms in key genes in the ara-C metabolic pathway, with the long-term goal of explaining the variability observed in treatment response and toxicity profile among AML patients receiving ara-C chemotherapy. The hypothesis of this research is that genetic polymorphisms in key genes in the ara-C metabolic pathway -specifically: deoxycytidine kinase (DCK, a rate limiting activating enzyme); 5'nucleotidase (NT5C2), deoxycytidine deaminase (CDA), and deoxycytidylate deaminase (DCTD) (3 main inactivating enzymes); human equilibrative nucleoside transporter (hENT1/ SLC29A1, ara-C uptake transporter); and ribonucleotide reductase (enzyme regulating intracellular dCTP pools, and consisting of RRM1 and RRM2 subunits) -form the molecular basis of the inter-patient variability observed in intracellular ara-CTP concentration and sensitivity to ara-C. This hypothesis is based on the observations that the above mentioned candidate genes have been shown by various in vitro and in vivo studies to be associated with the clinical response and/or sensitivity to ara-C and demonstrate a wide inter- patient variability in their expression. The specific aims of the proposed research are: 1) To identify and functionally characterize the coding genetic polymorphisms in key ara-C metabolic pathway genes in lymphoblast samples with European (CEPH) or African (YRI) ancestry; 2) To identify and characterize regulatory cis-genetic polymorphisms associated with mRNA expression of the candidate genes; and 3) To determine the association of functionally significant genetic polymorphisms in the candidate genes with clinical phenotypes such as candidate gene expression and ara-C sensitivity in diagnostic blasts, and intracellular ara- CTP levels and the extent of DNA synthesis inhibition in post ara-C treatment leukemic blasts from pediatric AML patients enrolled in the St. Jude AML2002 protocol. The use of CEPH and YRI samples will allow us to use HAPMAP genotype data and to study any ethnic differences in genotype frequencies and in candidate gene expression. The results from this study would also be applicable to other nucleoside analogs such as gemcitabine, decitabine, clofarabine, etc. that are metabolized by the same pathway. Understanding genetic variation in the key candidate genes involved in the metabolism of ara-C will provide us an opportunity to identify patients at increased risk of adverse reactions or decreased likelihood of response, based upon their genetic profile, which in future could help in dose optimization to reduce drug toxicity without compromising on efficacy. Relevance Statement: Acute myeloid leukemia (AML) is the second most common childhood leukemia and has the worst outcome of all major childhood cancers. Ara-C is the main drug used in AML chemotherapy but the cellular levels of its active form, ara-CTP, vary widely among patients and in turn are associated with variability in clinical response to ara-C treatment. The proposed research seeks to explain this variability by studying the inherited genetic variation in key genes involved in ara-C metabolism and may, in future, help to optimize ara-C dosing based on patient genetics.

描述（由申请人提供）：核苷类似物阿糖胞苷 (ara-C) 40 多年来一直是急性髓系白血病 (AML) 化疗的支柱，也是用于诱导 AML 患者缓解的最重要药物之一。许多研究表明，其活性代谢物 ara-CTP 的细胞内浓度在患者之间差异很大，进而与临床反应的变异性相关。当前提案的目的是通过识别和评估 ara-C 代谢途径中关键基因的遗传多态性的药物基因组效应，确定细胞内 ara-CTP 水平变化的分子基础，长期目标是解释接受 ara-C 化疗的 AML 患者中观察到的治疗反应和毒性特征的变异性。这项研究的假设是ara-C代谢途径中关键基因的遗传多态性——具体来说：脱氧胞苷激酶（DCK，一种限速激活酶）； 5'核苷酸酶（NT5C2）、脱氧胞苷脱氨酶（CDA）和脱氧胞苷酸脱氨酶（DCTD）（3种主要失活酶）；人平衡核苷转运蛋白（hENT1/SLC29A1，ara-C 摄取转运蛋白）；和核糖核苷酸还原酶（调节细胞内 dCTP 池的酶，由 RRM1 和 RRM2 亚基组成） - 形成在细胞内 ara-CTP 浓度和对 ara-C 敏感性中观察到的患者间变异性的分子基础。该假设基于这样的观察：各种体外和体内研究已表明上述候选基因与ara-C的临床反应和/或敏感性相关，并证明其表达存在广泛的患者间变异性。本研究的具体目标是： 1) 鉴定欧洲 (CEPH) 或非洲 (YRI) 血统的淋巴母细胞样本中关键 ara-C 代谢途径基因的编码遗传多态性并进行功能表征； 2) 鉴定和表征与候选基因的mRNA表达相关的调节性顺式遗传多态性； 3) 确定候选基因中功能显着的遗传多态性与临床表型的关联，例如诊断原始细胞中的候选基因表达和ara-C敏感性，以及加入St. Jude AML2002方案的儿科AML患者的细胞内ara-CTP水平和ara-C治疗后白血病原始细胞中DNA合成抑制的程度。 CEPH 和 YRI 样本的使用将使我们能够使用 HAPMAP 基因型数据并研究基因型频率和候选基因表达的任何种族差异。这项研究的结果也适用于通过相同途径代谢的其他核苷类似物，例如吉西他滨、地西他滨、氯法拉滨等。了解参与 ara-C 代谢的关键候选基因的遗传变异将为我们提供一个机会，根据患者的遗传图谱识别不良反应风险增加或反应可能性降低的患者，这将来可能有助于剂量优化，以在不影响疗效的情况下降低药物毒性。相关性声明：急性髓系白血病 (AML) 是第二常见的儿童白血病，并且是所有主要儿童癌症中预后最差的。 Ara-C 是 AML 化疗中使用的主要药物，但其活性形式 ara-CTP 的细胞水平在患者之间差异很大，进而与 ara-C 治疗的临床反应差异相关。拟议的研究旨在通过研究参与 ara-C 代谢的关键基因的遗传变异来解释这种变异性，并可能在未来帮助根据患者遗传学优化 ara-C 剂量。