Overexpression of cyclin D1 enhances gene amplification.

Defects in cell cycle control and increased genomic instability, including gene amplification, often occur during cancer development. Cyclin D1 plays a pivotal role in G1, and this gene is frequently amplified and overexpressed in several types of human cancer. This study demonstrates that ectopic overexpression of cyclin D1 in a rat liver epithelial cell line markedly increased the yield of cells containing amplified copies of the CAD gene. This effect was associated with a loss of G1-S checkpoint control, although the cyclin D1-overexpressing cells had a normal p53 gene. The capacity of cyclin D1 to enhance gene amplification may contribute to the process of genomic instability during tumor development.