GENE EXPRESSION INDICES IN CHEMORESISTANT LUNG CANCER

非小细胞肺癌(NSCLC)是我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，总体消退率仅为30%-50%。组织学分类提供的有关特定非小细胞肺癌组织生物学行为的信息极其有限。基因组计划的进展和高通量基因表达测量的进展为重新定义基于重要表型的非小细胞肺癌组织的诊断提供了机会，例如化疗耐药，而不是基于组织学。这项拟议研究的主要长期目标是提高对非小细胞肺癌化疗耐药的机制的了解，并开发一种预测哪些非小细胞肺癌肿瘤将发生反应的方法。耐药机制可能涉及多种基因产物。例如，在其他研究中，已经确定，在恶性表型(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)细胞株对卡铂的耐药性是H460的50倍。用标准化的竞争性模板混合物对20个可能与卡铂耐药相关的基因进行定量RT-PCR分析，结果显示谷胱甘肽转移酶(GST)p1、Baxα、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、20、10、6、5和4倍。这些基因和其他假定的化疗耐药基因可以有效地结合到基因表达指数中，产生更好的化疗耐药表型标记。这一建议的总体假设是，单个基因的表达模式和/或由多个单独基因的表达值组成的指数将为化疗耐药的非小细胞肺癌提供有效的标记物。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检验这一假说。目的1)检测原发NSCLC肿瘤组织中化疗耐药基因的表达，以确定哪些基因与耐药表型相关。目的2)确定与非小细胞肺癌肿瘤化疗耐药相关的基因表达指标；3)开发一种标准化的竞争性模板混合物，以实现基因表达数据的实验室间比较。目的：实现定量RT-PCR方法的自动化。目的5)建立一个基于互联网的数据库，用于存储在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.