Review: gene amplification--a cellular response to genotoxic stress.

Recent years of cancer research have defined the role of key regulatory genes in oncogenesis. Oncogenes and suppressor genes are affected in the process of carcinogenesis either by mutations within the coding region, promoter mutations, or gene amplification. This review describes our studies on gene amplification in mammalian cells, with emphasis on the initiating events induced by carcinogenic chemicals and various types of radiation. The influence of genomic instability, cell dedifferentiation, and the malignant potential of a cell on their capacity to amplify genes is demonstrated by molecular biologic and cytogenetic studies on human and rodent cells. Cells that contain amplified DNA are at risk for chromosomal aberrations, sister chromatid exchanges, and rearrangements. Surviving cells show such cancer-prone genetic consequences.