Restriction Landmark Genomic Scanning of mouse liver tumors for gene amplification: Overexpression of cyclin A2

SV40 T/t antigen-induced liver tumors from transgenic mice were analyzed by Restriction Landmark Genomic Scanning (RLGS). Using NotI as the restrictio n landmark, RLGS targets CpG islands found in gene-rich regions of the geno me. Since many RLGS landmarks are mapped, the candidate gene approach can b e used to help determine which genes are altered in tumors. RLGS analysis r evealed one tumor-specific amplification mapping close to CcnA2 (cyclin A2) and Fgf2 (fibroblast growth factor 2). Southern analysis confirmed that bo th oncogenes are amplified in this tumor and in a second, independent liver tumor. Whereas Fgf2 RNA is undetectable in tumors, CcnA2 RNA and cyclin A2 protein was overexpressed in 25 and 50% of tumors, respectively. Combining RLGS with the candidate gene approach indicates that cyclin A2 amplificati on and overexpression is a likely selected event in transgenic mouse liver tumors. Our results also indicate that our mouse model for liver tumorigene sis in mice accurately recapitulates events observed in human hepatocellula r carcinoma. (C) 2000 Academic Press.