CONGENIC STRAINS FOR GENES AFFECTING COLON TUMORS

这项提案的总体目标是测试小鼠的哪些区域 基因组，在初步实验中确定，有影响， 1，2-二氢喹啉标准治疗诱发的结肠肿瘤数量 二甲肼二盐酸盐（DMH）。 在对DMH诱导的结肠肿瘤的敏感性的早期研究中（Evans et al. 1977），最敏感的菌株是ICR/Ha（I），60/60只动物 在DMH治疗后有大量肿瘤，而大多数 耐药株为C57 BL/6 Ha（B），0/90有肿瘤。全部68 1XB F1杂交动物发展肿瘤。在回交中，（IXB）XB，46/117 动物长出了肿瘤。 重复伊布回交，在122个中的40个中检测到肿瘤 后代使用引物对的SSR-PCR（Dietrich等，1992）已经检测到 菌株1和B之间41%的引物对存在变异。的 对122个子代进行了90个位点的分型，每个位点至少有两个位点。 常染色体这些数据表明，肿瘤的形成是由几个因素控制的。 遗传位点位于第12条染色体中部的Ccs-1基因座与 D12Mit6（p <0.001）。其他基因测试确定了Chrs 2，3， 5，7，9，10，14，15和16。 为了确定11个基因区域的基因座是否 在回交中鉴定的影响DMH诱导的小鼠肿瘤形成， 建议产生同源菌株，其中，对于每种疑似菌株， 位点时，将敏感菌株的等位基因置于背景上 抵抗性菌株相互同源，其中等位基因 将来自抗性菌株的DNA置于敏感菌株的背景上， 也将被制造出来。共提出22个同源菌株。 来自这些同源品系的动物将用DMH处理， 在纯合和杂合状态下， 将确定肿瘤易感性。双同源株 将被制作出来并用于确定基因座对如何相互作用。 在这项工作的过程中，回交后代的数量将是 增加，这将改善联系的统计，并增加 荷瘤动物的数量。不同同源基因的肿瘤DNA 将使用菌株检测候选菌株的杂合性缺失 基因.肿瘤RNA将用于确定候选基因的表达。 来自现有近交系和现有同类系的DNA将被 用于获得框架图的基因座，尤其是那些 在11个确定的区域中，为了确定仅在 这些基因座中的1或2个。来自这些品系的动物将用DMH处理 以确定这些区域的等位基因的影响。

The overall goal of this proposal is to test which regions of the mouse genome, identified in preliminary experiments, have an effect on the number of colon tumors induced by a standard treatment with 1,2- dimethylhydrazine dihydrochloride (DMH). In an early study on sensitivity to DMH-induced colon tumors (Evans et al. 1977), the most sensitive strain was ICR/Ha (I), with 60/60 animals having large numbers of tumors after DMH treatment, while the most resistant strain was C57BL/6Ha (B), with 0/90 having tumors. All 68 1XB Fl hybrid animals developed tumors. In a backcross, (IXB)XB, 46/117 animals developed tumors. The IBB backcross has been repeated and tumors were detected in 40 of 122 progeny. SSR-PCR using primer pairs (Dietrich et al. 1992) has detected variation between strains 1 and B for 41% of the primer pairs tested. The 122 progeny have been typed for 90 loci with at least two loci per autosome. The data suggest that tumor formation is controlled by several genetic loci. The major locus, Ccs-1, on central Chr 12 was linked to Dl2Mit6 (p <0.001). Other genetic tests identified loci on Chrs 2, 3, 5,7, 9, 10, 14, 15 and 16. To determine whether or not the loci at the eleven genetic regions identified in the backcross affect DMH-induced tumor formation in mice, it is proposed to generate congenic strains in which, for each suspected locus, the allele from the sensitive strain is placed on the background of the resistant strain. The reciprocal congenic, in which the allele from the resistant strain is placed on the background of the sensitive strain, will -also be made. A total of 22 congenic strains are proposed. Animals from each of these congenic strains will be treated with DMH and the effect of each allele, in both the homozygous and heterozygous state, on tumor - susceptibility will be determined. Double congenic strains will be made and used to determine how pairs of loci interact. In the course of this work, the number of backcross progeny will be increased, which will improve the statistics of linkage and increase the number of tumor-bearing animals. Tumor DNA from different congenic strains will be used to test for loss of heterozygosity of candidate genes. Tumor RNA will be used to determine expression of candidate genes. DNA from existing inbred strains and existing congenic strains will be typed for loci used to obtain the framework map, especially those loci in the eleven identified regions, to identify strains differing at only l or 2 of these loci. Animals from these strains will be treated with DMH to determine the effects of alleles from these regions.