title: 6;7 chromosomal translocation in spontaneously arising rat immunocytomas: evidence for c-myc breakpoint clustering and correlation between isotypic expression and the c-myc target.
abstract: Our previous studies have shown that spontaneously arising immunocytomas in the LOU/Ws1 strain of rats contain a t(6;7) chromosomal translocation in all seven tumors studied (F. M. Babonits, J. Spira, G. Klein, and H. Bazin, Int. J. Cancer 29:431-437, 1982). We have also shown that the c-myc is located on chromosome 7 (J. Sümegi, J. Spira, H. Bazin, J. Szpirer, G. Levan, and G. Klein, Nature (London) 306:497-499, 1983) and the immunoglobulin H cluster on chromosome 6 (W.S. Pear, G. Wahlström, J. Szpirer, G. Levan, G. Klein, and J. Sümegi, Immunogenetics 23:393-395, 1986). We now report a detailed cytogenetic and molecular analysis of nine additional rat immunocytomas. The t(6;7) chromosomal translocation is found in all tumors. Mapping of the c-myc breakpoints showed that in 10 of 14 tumors, the c-myc breakpoints are clustered in a 1.5-kilobase region upstream of exon 1. In contrast with sporadic Burkitt's lymphoma and mouse plasmacytoma, only 1 of 14 tumors contains the c-myc breakpoints in either exon 1 or intron 1. Analysis of the sequences juxtaposed to the c-myc show that immunoglobulin H switch regions are the targets in at least five tumors and that there is a strong correlation between the secreted immunoglobulin and the c-myc target. Unlike sporadic Burkitt's lymphoma and mouse plasmacytoma, at least two rat immunocytomas show recombination of the c-myc with sequences distinct from immunoglobulin switch regions.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D004273:DNA, Neoplasm / Q000235:genetics*; D005786:Gene Expression Regulation; D005803:Genes, Immunoglobulin; D005812:Genes, Switch; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007132:Immunoglobulin Isotypes / Q000235:genetics*; D007621:Karyotyping; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010954:Plasmacytoma / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051381:Rats; D014178:Translocation, Genetic
chemical_list: D004273:DNA, Neoplasm; D007127:Immunoglobulin Constant Regions; D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes; D011518:Proto-Oncogene Proteins