Mammary gland neoplasia: insights from transgenic mouse models

Current theories of breast cancer progression have been greatly influenced by the development and refinement of mouse transgenic and gene targeting te chnologies. Early transgenic mouse models confirmed the involvement of onco genes, previously implicated in human breast cancer, by establishing a caus al relationship between overexpression or activation of these genes and mam mary tumorigenesis. More recently, the importance of genes located at sites of loss of heterozygosity in human breast cancer have been examined in mic e by their targeted disruption via homologous recombination, The union of t hese two approaches allows the generation of complex animal models that mor e accurately reflect the multistep nature of human breast cancer. This revi ew will examine how the study of transgenic mice has increased our understa nding of the molecular events responsible for oncogenic transformation of t he mammary gland. BioEssays 22:554-583, 2000, (C) 2000 John Wiley & Sons, I nc.