Pharmacogenomics of the chemotherapeutic agent paclitaxel

描述(申请人提供)：化疗药物基因组学研究的长期目标是使用遗传信息来识别有特定药物诱导毒性风险的癌症患者，并相应地调整或改变他们的治疗方法。这项建议的目标是发现并从功能上验证预测化疗药物紫杉醇治疗结果的遗传标记。紫杉醇是一种稳定微管的化疗药物，常用于乳腺癌、卵巢癌和非小细胞肺癌的治疗，但个体之间不同的耐药性和毒性限制了成功的结果。紫杉醇引起的常见毒性包括周围感觉神经病和肾毒性，这导致大约20%的患者停止治疗。药物反应的变异很可能取决于多种基因产物的变异和环境因素的综合影响。利用经典的基于SNP的全基因组关联(GWA)方法，在受控环境下研究了紫杉醇诱导的淋巴母细胞系(LCLS)细胞毒性的遗传学。初步分析表明，来自紫杉醇诱导的周围神经病变临床试验的顶级SNPs富含与紫杉醇诱导的LCLS细胞毒性相关的SNPs，从而证实了LCL模型在分析与患者紫杉醇反应相关的基因方面的作用。初步分析的重叠SNP位于RFX2的一个内含子中。通过siRNA降低该基因的表达导致NS-1细胞对紫杉醇的敏感性增加，通过减少突起生长和增加细胞毒性来衡量，从功能上证实了RFX2参与了紫杉醇的敏感性。虽然这种方法成功地识别了一个重要的基因，但我们的计划是进行基于基因的GWA研究，因为我们意识到，使用传统的基于SNP的GWA方法可能无法检测到一些相关的遗传变异。一种新的基于基因的方法，结合表达数量性状基因座(EQTL)、罕见和常见的编码变体以及其他功能信息，共同检测小效应变异，将增加与紫杉醇敏感性相关的基因水平测试的能力。该研究员和研究团队还计划将基于基因的LCL结果与临床研究的结果进行比较。重叠的基因将成为进行功能测试的优秀候选基因 在周围神经病的细胞模型中。在计算分析中确定的其他基因将在NS-1模型中进行测试。因此，除了识别导致紫杉醇诱导表型变化的新标记外，这些实验还将加强对紫杉醇反应机制的理解。这项工作将为选择来自LCL GWA研究的SNPs和基因在未来的临床研究中进行询问提供一个框架。通过完成这项提议的目标，该研究员将在人类遗传学和分子生物学领域获得经验，同时为转化型癌症研究领域做出贡献。

DESCRIPTION (provided by applicant): The long-term goal of chemotherapeutic pharmacogenomics research is to use genetic information to identify cancer patients at risk of particular drug-induced toxicities and adjust or alter their treatment accordingly. The goal of thi proposal is to discover and functionally validate genetic markers that predict treatment outcomes of the chemotherapeutic agent paclitaxel. Paclitaxel is a microtubule-stabilizing chemotherapy drug often used in the treatment of breast, ovarian and non-small-cell lung cancers, yet variable resistance and toxicities among individuals limit successful outcomes. Common paclitaxel-induced toxicities include peripheral sensory neuropathy and nephrotoxicity, which lead to discontinuation of therapy in approximately 20% of patients. Variation in drug response is likely to be dependent on the combined effects of variation in multiple gene products and environmental factors. By using a classic SNP-based genome-wide association (GWA) approach, the genetics of paclitaxel-induced cytotoxicity has been investigated in lymphoblastoid cell lines (LCLs) under a controlled environment. A preliminary analysis has shown that the top SNPs from a clinical trial of paclitaxel-induced peripheral neuropathy are enriched for SNPs associated with paclitaxel-induced cytotoxicity in LCLs, thus confirming a role for the LCL model in the analysis of genes involved in patient paclitaxel response. An overlap SNP from the preliminary analysis is located in an intron of RFX2. Decreased expression of this gene by siRNA resulted in increased sensitivity of NS-1 cells to paclitaxel measured by reduced neurite outgrowth and increased cytotoxicity, functionally validating the involvement of RFX2 in paclitaxel sensitivity. Although this approach was successful in identifying an important gene, our plan is to perform gene-based GWA studies because we realize that some of the associated genetic variants may not be detectable using a traditional SNP-based GWA approach. A novel gene-based approach to detect variants of small effect working together that incorporates expression quantitative trait loci (eQTLs), rare and common coding variants, and other functional information will increase power in a gene-level test for association with paclitaxel sensitivity. The fellow and research team also plan to compare the gene-based LCL results to those from clinical studies. Genes that overlap will make excellent candidates to test functionally in cell models of peripheral neuropathy. Additional genes identified in the computational analyses will be tested in the NS-1 model. Thus, in addition to identifying novel markers that contribute to variation in paclitaxel-induced phenotypes, these experiments will enhance understanding of the mechanisms involved in paclitaxel response. This work will provide a framework for choosing SNPs and genes that come from LCL GWA studies to interrogate in future clinical studies. By completing the aims of this proposal, the fellow will gain experience i human genetics and molecular biology while contributing to the field of translational cancer research.