MOLECULAR GENETICS OF LUNG TUMOR PROMOTION IN MICE

摘要 使用不同品系的近交系小鼠进行的遗传连锁研究已经绘制了肺 腺瘤易感性（Pas）和肺腺瘤耐药（Par）基因座[1，2]。最近， 数量性状基因座（QTL）定位也确定了调控遗传的特定基因座， 使用近交系小鼠品系对肺部炎症的易感性[3]。有趣的是， 发现染色体位置调节肺部炎症和癌变 提示肺部炎症在肺部肿瘤易感性中的因果作用[3]。我们 假设肺部炎症的遗传修饰因子可以通过F2连锁来鉴定 在小鼠中进行定位，然后进行精细定位策略。提出了四个具体目标， 实现我们的目标。在具体目标1中，我们将进行肺结核的遗传连锁图谱， 在暴露于肺刺激物二丁基羟基甲苯（BHT）的小鼠中，在 BHT与致癌物3-甲基胆蒽（MCA）结合，可促进MCA诱导的肺 肿瘤发生我们建议使用两种小鼠品系（BALB/cByJ和 C57 BL 6/J）具有极端炎症和炎症诱导的肿瘤促进表型。在 目的2，我们将进行单倍型和全基因组连锁不平衡分析， 发现新的QTL并指导和告知目标3中要靶向的位点。我们最近 论证了关联分析在精细作图和识别中的可行性 肺腺癌的候选易感基因[4]。目标3将精细定位主效QTL 与肺部炎症和肿瘤促进的遗传易感性有关， 产生其中炎症易感等位基因被取代的同类小鼠品系 对炎症抵抗小鼠的遗传背景进行研究。QTL将通过以下方式进行精细定位： 通过产生亚同源小鼠品系逐渐减少QTL区域， 缩小到0.5-1厘米左右。目的4将通过位置分析来鉴定候选基因。 克隆。精细定位区域的DNA序列将通过比较 完成小鼠基因组数据库。候选基因将根据已鉴定的 两个亲本小鼠品系之间的功能多态性和表达差异 在疾病发展的不同阶段。这些研究的意义在于， 确定可能也有助于 人类肺癌的遗传易感性。

ABSTRACT Genetic linkage studies using various strains of inbred mice have mapped pulmonary adenoma susceptibility (Pas) and pulmonary adenoma resistance (Par) loci [1,2]. Recently, quantitative trait locus (QTL) mapping also identified specific loci that regulate genetic susceptibility to pulmonary inflammation using inbred mouse strains [3]. Interestingly, common chromosomal locations were found to regulate both pulmonary inflammation and carcinogenesis suggesting a causal role of pulmonary inflammation in lung tumor susceptibility [3]. We hypothesize that genetic modifiers of pulmonary inflammation can be identified using F2 linkage mapping in mice followed by fine mapping strategies. Four specific aims are proposed to accomplish our goal. In Specific Aim 1, we will conduct genetic linkage mapping of pulmonary inflammation QTL in mice exposed to the lung irritant, butylated hydroxytoluene (BHT). In combination with the carcinogen 3-methylcholanthrene (MCA), BHT promotes MCA-induced lung tumorigenesis. We propose to use the F2 progeny of two strains of mice (BALB/cByJ and C57BL6/J) with extreme inflammation and inflammation-induced tumor promotion phenotypes. In Aim 2, we will conduct haplotype and whole-genome linkage disequilibrium analyses to guide discover new QTLs and guide and inform which loci to target in Aim 3. We have recently demonstrated the feasibility of association analysis in the fine mapping and identification of candidate susceptibility genes for lung adenocarcinomas [4]. Aim 3 will fine map the major QTL related to genetic susceptibility to pulmonary inflammation and tumor promotion by the production of congenic strains of mice in which the inflammation susceptible allele is substituted onto the genetic background of the inflammation resistant mice. The QTL will be fine-mapped by progressively reducing the QTL region through the production of sub-congenic mouse strains to narrow it to a size of around 0.5-1 cM. Aim 4 will identify the candidate gene(s) by positional cloning. DNA sequences of the fine mapped region will be obtained through comparison of completed mouse genomic databases. Candidate genes will be identified based on identified functional polymorphisms and differences in expression between the two parental strains of mice at different stages of disease progression. The significance of these studies is that they will identify candidate pulmonary inflammation susceptibility genes that may also contribute to genetic susceptibility to lung cancer in humans.