GENE EXPRESSION INDICES IN CHEMORESISTANT LUNG CANCER

非小细胞肺癌（NSCLC）是美国最常见的癌症死亡原因之一，对目前的化疗方案反应较差，总体退行率仅为30- 50%。组织学分类提供了一个特定的非小细胞肺癌组织的生物学行为极其有限的信息。基因组计划的进展和基因表达高通量测量的进展，为基于重要表型（如化疗耐药）而不是基于组织学重新定义非小细胞肺癌组织的诊断提供了机会。这项研究的主要长期目标是提高对非小细胞肺癌化疗耐药机制的理解，并开发一种预测哪些非小细胞肺癌肿瘤会对化疗耐药产生反应的方法。耐药机制可能涉及多种基因产物。例如，在其他研究中，当恶性表型（c-myc x E2F-1/p21）和肺癌风险（GSTP1 x mGST x GSHPx）时，在支气管上皮细胞中测量的由多个独立基因表达值组成的指数比单个基因表达值具有更好的相关性。在初步研究中，H1435非小细胞肺癌（NSCLC）细胞系对卡铂的耐药性比H460高50倍。使用标准化竞争模板的定量RT-PCR方法对20个可能与卡铂化学耐药相关的基因进行了评估，结果显示，谷胱甘肽转移酶（GST） p1、Bax α、GADD45、ERCC3、谷胱甘肽过氧化物酶和mGST基因在H1435中的表达水平分别高出100倍、20倍、10倍、6倍、5倍和4倍。这些基因和其他推测的耐药基因可以有效地组合成基因表达指数，从而产生更好的耐药表型标记。该建议的总体假设是，个体基因表达模式和/或包含多个个体基因表达值的指数将为化疗耐药NSCLC肿瘤提供有效的标志物。一个国家合作肿瘤特征小组已经成立，通过完成以下具体目标来检验这一假设。目的1)测量原发性NSCLC肿瘤组织中推定的耐药基因的表达，然后确定哪些基因（如果有的话）与耐药表型相关。2)确定与NSCLC肿瘤化疗耐药相关的基因表达指数3)开发标准化的竞争性模板混合物，以便在实验室间比较基因表达数据。4)自动化定量RT-PCR方法。目标5)开发一个基于互联网的数据库，用于存储本研究期间获得的数据和存储其他实验室获得的数据。

Non-small cell lung cancer (NSCLC) is one of the most common causes of cancer death in this country and it is poorly responsive to current chemotherapeutic regimens with an overall regression rate of only 30-50 percent. Histological categorization provides extremely limited information regarding biological behavior of a particular NSCLC tissue. Progress in the genome project and advances in high throughput measurement of gene expression are providing the opportunity to re-define diagnosis of NSCLC tissues on the basis of important phenotypes, such as chemoresistance, rather than on the basis of histology. The primary long-term objectives of the proposed investigation are to improve mechanistic understanding of NSCLC chemoresistance and to develop a method for predicting which NSCLC tumors will respond. The mechanisms of resistance likely to involve multiple gene products. For example, in other studies it was determined that indices comprising multiple independent gene expressions values measured in bronchial epithelial cells correlated better than individual gene expression values when phenotypes for malignancy (c-myc x E2F-1/p21) and risk for lung cancer (GSTP1 x mGST x GSHPx). In preliminary studies, the H1435 non-small cell lung cancer (NSCLC) cell line is 50-fold more resistant to carboplatin than H460. Evaluation of 20 genes putatively associated with carboplatin chemoresistance using standardized mixtures of competitive templates in quantitative RT-PCR revealed that glutathione transferase (GST) p1, Bax alpha, GADD45, ERCC3, glutathione peroxidase and mGST genes are expressed at 100, 20, 10, 6, 5, and 4-fold higher levels respectively in H1435. These genes and other putative chemoresistance genes may be effectively combined into gene expression indices to produce a better marker for the chemoresistant phenotype. The over-all hypothesis of this proposal is that patterns of individual gene expression and/or indices comprising the expression values of multiple individual genes will provide an effective marker for chemoresistant NSCLC tumors. A National Cooperative Tumor Signature Group has assembled to test the hypothesis through completion of the following specific aims. AIM 1) Measure expression of putative chemoresistant genes in primary NSCLC tumor tissues then identify which, if any, correlate with resistant phenotype. AIM 2) Identify gene expression indices that correlate with NSCLC tumor chemoresistance AIM 3) Develop a standardized mixture of competitive templates that will allow inter-laboratory comparison of gene expression data. AIM 4) Automate the quantitative RT-PCR method. AIM 5) Develop an internet based databank for storage of the data acquired during this study and for storage of data acquired by other laboratories.