GENE EXPRESSION INDICES IN CHEMORESISTANT LUNG CANCER

非小细胞肺癌（NSCLC）是该国癌症死亡的最常见原因之一，对目前的化疗方案反应不良，总体消退率仅为30- 50%。 组织学分类提供了关于特定NSCLC组织生物学行为的极其有限的信息。 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（如化疗耐药性）而不是基于组织学重新定义NSCLC组织的诊断提供了机会。该研究的主要长期目标是提高对NSCLC耐药机制的理解，并开发一种预测哪种NSCLC肿瘤将有反应的方法。 抗性机制可能涉及多个基因产物。 例如，在其他研究中，确定了当恶性表型（c-myc x E2 F-1/p21）和肺癌风险（GSTP 1 x mGST x GSHPx）时，包括在支气管上皮细胞中测量的多个独立基因表达值的指数比个体基因表达值更好地相关。 在初步研究中，H1435非小细胞肺癌（NSCLC）细胞系对卡铂的耐药性是H460的50倍。 在定量RT-PCR中使用标准化的竞争性模板混合物对与卡铂耐药相关的20个基因进行评估，结果显示谷胱甘肽转移酶（GST）p1、Bax α、GADD 45、ERCC 3、谷胱甘肽过氧化物酶和mGST基因在H1435中的表达水平分别高100、20、10、6、5和4倍。 这些基因和其他假定的耐药基因可以有效地组合成基因表达指数，以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/或包括多个个体基因表达值的指数将为化学抗性NSCLC肿瘤提供有效的标志物。 一个国家合作肿瘤签名小组已经聚集在一起，通过完成以下具体目标来测试这一假设。 目的1）检测原发性非小细胞肺癌（NSCLC）肿瘤组织中可能存在的化疗耐药基因的表达，并确定其与耐药表型的相关性。 目的2）筛选与非小细胞肺癌化疗耐药相关的基因表达指标 目的3）开发一种标准化的竞争性模板混合物，这将允许基因表达数据的实验室间比较。 目的4）实现定量RT-PCR方法的自动化。 目的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.