Comparison of chemically induced and spontaneous murine thymic lymphomas in RF and AKR mice: differential expression of c-myc and c-myb.
Expression of 11 cellular oncogenes was determined in normal vs. lymphomatous thymic tissues of RF and AKR mice; only c-myc and c-myb transcripts were detected in an age-inappropriate pattern in thymomas. Normal thymocytes from young RF mice contained RNA transcripts of both genes, but the transcripts were no longer detected at 9 or more weeks of age. More than 90% of RF thymomas, occurring at 20-28 weeks of age after skin painting with 3-methylcholanthrene at 12 weeks, contained c-myc transcripts, and 70% of the tumors contained c-myb transcripts. Seven cell lines derived from these 3-methylcholanthrene thymomas expressed both cellular genes, as did 2 rare spontaneous thymomas of 12-month-old RF mice. No indication of rearrangement or amplification of either gene was seen in any of the RF tumors or cell lines. In AKR mice, transcripts of the 2 genes persisted longer in the normal thymus than in RF mice, but they were no longer detected at 26 weeks of age. Of 3 thymomas in 6-month-old 3-methylcholanthrene-treated AKR mice, all expressed c-myb and 2 expressed c-myc. Among 11 spontaneous AKR thymomas, however, only 2 showed detectable levels of both genes, and 2 more expressed c-myc or c-myb but not both.
D000818:Animals; D004247:DNA / Q000032:analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D005786:Gene Expression Regulation; D008223:Lymphoma / Q000139:chemically induced / Q000235:genetics*; D051379:Mice; D008806:Mice, Inbred AKR; D008815:Mice, Inbred Strains; D009857:Oncogenes; D013945:Thymoma / Q000139:chemically induced / Q000235:genetics*; D013950:Thymus Gland / Q000032:analysis; D013953:Thymus Neoplasms / Q000139:chemically induced / Q000235:genetics*
D004273:DNA, Neoplasm; D004247:DNA