OVEREXPRESSION OF CYCLIN D1 ENHANCES GENE AMPLIFICATION

Defects in cell cycle control and increased genomic instability, inclu ding gene amplification, often occur during cancer development. Cyclin D1 plays a pivotal role in G(1), and this gene is frequently amplifie d and overexpressed in several types of human cancer. This study demon strates that ectopic overexpression of cyclin D1 in a rat liver epithe lial cell line markedly increased the yield of cells containing amplif ied copies of the CAD gene. This effect was associated with a loss of G(1)-S checkpoint control, although the cyclin D1-overexpressing cells had a normal p53 gene. The capacity of cyclin D1 to enhance gene ampl ification may contribute to the process of genomic instability during tumor development.