中文摘要：

为了克隆儿童急性淋巴细胞性白血病（ALL）候选肿瘤抑制基因，首先选取分布于6q16.3～21上的11个多态性微卫星标记，对139例中国儿童ALL标本进行杂合性缺失（LOH）分析．分析显示32％的患者存在至少一个位点的LOH，且高频缺失区位于D6S1709～D6S301之间，大小为2cM．各位点LOH与白细胞总数、病态细胞数有显著性相关（P〈0．05），与年龄、性别、形态学分型和免疫学分型无显著相关（P〉0．05）．进一步在高频缺失区域内，采用定位候选克隆策略、生物信息学技术及RT—PCR技术筛选、鉴定与儿童ALL相关的候选肿瘤抑制基因及其cDNA片段．在D6S1709～D6S301之间筛选到一个在儿童ALL细胞中低表达的EST（GenBank登录号：AA403058），与正常外周血单个核细胞比较，在15例ALL患者中有10例表达下调（P〈0．05）．采用数字化差异表达分析显示，位于6q16.3～21区域内的AMD1基因、PPIL6基因和WASF1基因在肿瘤组织中的表达丰度要低于正常组织（P〈0．05）．上述结果为进一步在6q16.3～21区域克隆肿瘤抑制基因提供了线索．

英文摘要：

In order to identify candidate tumor suppressor genes （TSGs） in childhood acute lymphoblastic leukemia （ALL）, firstly, loss of heterozygosity （LOH） of 6q16.3 - 21 in 139 primary ALL samples was analyzed by using polymerase chain reaction （PCR） and 11 microsatellite markers. The frequency of LOH on 6q16.3-21 was 32%. A 2-cM high frequency deletion region was flanked by D6S1709 and D6S301 loci at 6q16.3-21. Clinical data showed that patient with 6q16.3-21 LOH had higher WBC counts and blast cells （P 〈 0.05）. The statistics about age, sex, classification of morphology and immunology were indistinct （P 〉 0.05）. Then, positional cloning strategy, bioinformatics technology and reverse transcription-polymerase chain reaction （RT-PCR） were used to identify candidate TSGs and its eDNA fragments at 6q16.3-21, especially at the high frequency deletion region. Comparing with expression of normal peripheral blood mononuclear cell, EST screened in D6S1709-D6S301 （GenBank Accession No.AA403058） was down-regulation in ten of fifteen childhood ALL （P 〈 0.05）. Digital differential display showed that the expression levels of AMD1, PPIL6 and WASF1 were lower in cancer tissues than in normal tissues（P 〈 0.05）. These findings may provide new clues in cloning of childhood ALL TSGs at 6q16.3-21.