Kuschak TI, Taylor C, McMillan-Ward E, Israels S, Henderson DW, Mushinski JF, Wright JA, Mai S. The ribonucleotide reductase R2 gene is a non-transcribed target of c-Myc-induced genomic instability.
Gene 1999;
238:351-65. [PMID:
10570963 DOI:
10.1016/s0378-1119(99)00341-8]
[Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The c-Myc oncoprotein is highly expressed in malignant cells of many cell types, but the mechanism by which it contributes to the transformation process is not fully understood. Here, we show for the first time that constitutive or activated overexpression of the c-myc gene in cultured mouse B lymphocytes is followed by chromosomal and extrachromosomal amplification as well as rearrangement of the ribonucleotide reductase R2 gene locus. Electron micrographs and fluorescent in situ hybridization (FISH) demonstrate the c-Myc-dependent generation of extrachromosomal elements, some of which contain R2 sequences. However, unlike other genes that have been shown to be targets of c-Myc-dependent genomic instability, amplification of the R2 gene is not associated with alterations in R2 mRNA or protein expression. These data suggest that c-Myc-dependent genomic instability involves a greater number of genes than previously anticipated, but not all of the genes that are amplified in this system are transcriptionally upregulated.
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