Elevated cellular polyamine levels enhance promoter activity in vivo

Polyamines are small polycationic molecules that have been implicated in cell growth, differentiation and transformation. A possible mechanism for their involvement in these processes is via their influence on the expression of growth promoting genes. In this study we used an ornithine decarboxylase (ODC) overexpressing retroviral system to achieve high intracellular levels of polyamines in epidermal cells. We then looked at the effect this environment had on transcription from several promoter-reported gene constructs, including c-myc and ODC itself. In transient transfection studies elevated polyamines significantly enhanced the transcriptional activity of all promoters tested. In addition, reporter gene expression was induced approximately 3 fold in stable transformants containing an integrated c-myc or ODC promoter-reporter gene construct suggesting that elevated levels of polyamines, such as those found in transformed cells, have a stimulatory effect on gene expression.