H-rev107-1 is a growth inhibitory RAS target gene capable of suppressing anchorage independent growth in vitro and in vivo. Using a tumour tissue array with 241 matched tumour and normal tissue cDNA pools, we found down-regulation of H-REV107-1 in 7 out of 14 ovary-derived cDNAs. RT-PCR analysis and immunohistochemical investigation confirmed expression of H-REV107-1 in normal ovarian epithelial cells but down-regulation in high grade ovarian carcinomas. H-REV107-1 is also strongly expressed in immortalized rat and human ovarian epithelial cells in vitro, but suppressed in transformed cells by two different mechanisms. KRAS-transformed rat ovarian cells and PA1 teratocarcinoma cells, reversibly repress H-REV107-1 via MAP/ERK signaling. In contrast, treatment of A27/80 and OVCAR-3 epithelial ovarian cancer cells with IFNgamma stimulated H-REV107-1 expression. In NIH3T3 cells harbouring an estrogen-inducible IRF-1, H-rev107-1 is directly induced after activation of IRF-1, indicating that H-rev107-1 is a target of IRF-1. Stimulation of H-REV107-1 expression was also observed in ovarian epithelial cells suggesting that IRF-1 is involved in H-REV107-1 regulation in human ovarian epithelium. In the IFNgamma-sensitive cell line A27/80, H-REV107-1 suppresses colony formation. A27/80 and OVCAR-3 cells overexpressing H-REV107-1 protein underwent apoptosis. These results demonstrate down-regulation of the class II tumour suppressor H-REV107-1 in human ovarian carcinomas and suggest an involvement of H-REV107-1 in interferon-dependent cell death.