Human epithelial cancers are defined by a recurrent distribution of specific chromosomal aneuploidies. In our model system, mouse bladder and kidney epithelial cells spontaneously immortalize, transform and become tumorigenic after prolonged culture. We assessed genome and transcriptome alterations and found wide-spread aneuploidy, early transcriptional deregulation, and massive genomic dereguation of the cellular transcriptome. The results reveal a remarkable similarity with genome and transcriptome aberrations detected in human tumorigenesis, hence validating our newly derived cancer models. Epithelial cells were isolated from the C57BL/6 mouse bladder and kidney. These cells underwent spontaneous transformation in culture. We sought to identify the molecuar genomic alterations that occur during the transformation process and to compare these with the changes observed in human bladder and kidney cancers.