Role of polyamines in mediating malignant transformation and oncogene expression

Previous studies have demonstrated that polyamines accumulate in cancer cells and that overproduction of ornithine decarboxylase (ODC), which catalyzes polyamine synthesis, elicits the acquisition of the transformed phenotype. However, it was not clear whether the expression of ODC and the accumulation of polyamines are only innocent by-products of the transformation process. In this study we confirm previous findings what polyamines can trigger the transformation of immortalized cultured cells. In addition to NIH 3T3 fibroblasts, studied previously, rat kidney epithelial cells or fibroblasts also grew in soft agar in the presence of polyamines. It has also been demonstrated that spermidine, preferentially stimulated the transcription and the expression of c-myc while those of c-fos were preferentially stimulated by putrescine. These findings suggest that the effect of polyamines on cellular transformation, could be explained, at least partially, by stimulation of proto-oncogene expression.