Allelotype analysis of 2',3'-dideoxycytidine- and 1,3-butadiene-induced lymphomas in B6C3F1 mice

To identify potential tumor suppressor genes involved in lymphoma development, we generated allelotypes of 16 2',3'-dideoxycytidine (ddC and 31 1,3-butadiene (BD)-induced lymphomas from C57BL/6 x C3H/He F1 (hereafter called B6C3F1) mice. Two or more anonymous simple sequence length polymorphisms per autosome were examined for loss of heterozygosity (LOH). Allelic losses throughout the genome were generally infrequent, except for markers on chromosome 2, 4, 11 and 12. The highest frequency of allelic losses was observed on chromosome 12, with 38 and 39% in ddC and BD-induced lymphomas, respectively. The most prevalent LOH was localized to the distal region bounded by markers D12Mit263 and D12Nds2. No known tumor suppressor genes have been mapped to this region, and no obvious candidates could be identified, suggesting the presence of novel suppressor gene(s). LOH on chromosome 2 was observed in 31% of ddC-induced lymphomas but in only 3% (1/31) of BD-induced lymphomas, suggesting a ddC-specific genetic effect. Detailed analysis localized a potential tumor suppressor gene residing on the distal region of chromosome 2, between markers D2Mit147 and D2Mit148. Twenty-five % of ddC-induced and 23% of BD-induced lymphomas showed LOH on chromosome 4, and two discrete regions were identified. One of the regions includes the IFN gene cluster and is syntenic to human chromosome 9p2l-22. Candidate tumor suppressor genes, Mts1 (multiple tumor suppressor 1) and Mts2 have been mapped to this region. The second region is located on the distal part of chromosome 4, which is homologous to human chromosome 1p35-36, a region that is frequently deleted in various types of human tumors. Finally, 19% of ddC-induced and 29% of BD-induced lymphomas revealed LOH on chromosome 11 at the Acrb locus, which lies within 1 cM of p53, suggesting that the p53 tumor suppressor gene also plays a role in lymphomagenesis. These results suggest that multiple potential suppressor loci contribute to lymphoma development in B6C3F1 mice.