Overexpression of E2F-1 in lung and liver metastases of human colon cancer is associated with gene amplification.

We have shown previously that metastatic tumors of human colorectal cancer in lung as compared to liver have high levels of thymidylate synthase (TS) mRNA expression that correlated with high levels of E2F-1 mRNA expression. We now report that Comparative Genomic Hybridization (CGH) and DNA PCR analyses of lung and liver metastases of human colon cancer show frequent gains in the region of chromosome 20q and have an increase in gene copy number of E2F-1. In as much as TS is transcriptionally regulated by E2F-1, these results provide an explanation for the high levels of TS mRNA noted in some tumor samples.