Altered structure and expression of c-myc in feline T-cell tumours.
The c-myc gene is rearranged in a subset of feline T-cell lymphosarcomas. Detailed mapping of c-myc rearrangements showed that some result from feline leukaemia virus (FeLV) proviral integration within or upstream of c-myc, but one case involves a complex 3' alteration and amplification which is apparently not directly virus-induced. S1 nuclease mapping of RNA from normal cells using c-myc probes revealed two presumptive 5' ends, each corresponding to a promoter-like sequence (P1 and P2), and a major 3' discontinuity which mapped to the 3'-most of two possible polyadenylation signals. Analysis of RNA from a series of tumours revealed different modes of c-myc expression. All tumours produced P1 and P2 transcripts with apparently normal structure except for one case where an insertion in intron 1 displaced exon 1 sequences. The abundance ratio of P1/P2 transcripts varied considerably and was high in tumours which carry a rearrangement adjacent to c-myc, but some other T-cell tumours with no apparent myc alteration displayed an equally high ratio. However, a consistent feature was the lack of detectable RNA from normal c-myc alleles in tumours which express a rearranged c-myc allele or a transduced FeLV v-myc gene. We suggest that this may prove to be a useful indicator of the presence of an oncogenically active myc gene, whether this is a rearranged c-myc or transduced v-myc sequence.
D000483:Alleles; D000818:Animals; D002415:Cats; D005091:Exons; D005784:Gene Amplification; D005814:Genes, Viral; D007438:Introns; D005256:Leukemia Virus, Feline / Q000235:genetics*; D008228:Lymphoma, Non-Hodgkin / Q000235:genetics* / Q000382:microbiology; D009857:Oncogenes; D011401:Promoter Regions, Genetic; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D013953:Thymus Neoplasms / Q000235:genetics* / Q000382:microbiology; D014158:Transcription, Genetic
D012334:RNA, Neoplasm