RESUMO
INTRODUCTION: Peroxisome proliferator-activated receptor gamma (PPAR-gamma) and retinoic acid receptors (RAR/RXR) belong to the nuclear steroid receptor family. In vitro studies have suggested that PPAR-gamma ligands are highly effective in preventing mammary tumours and these effects are enhanced by some retinoids. However, in vivo anti-initiator and anti-promoter efficacies of this combination are not clear. AIM AND METHODS: The present study aimed to investigate the chemopreventive efficacies of the PPAR-gamma ligand rosiglitazone (200 microg/kg/day), synthetic retinoid fenretinide (0.3 mg/kg/day) and their combination on a DMBA-induced rat mammary carcinogenesis model. RESULTS: In the rosiglitazone group, no malignant tumour developed, apart from the lowest proliferative mammary lesions. In the fenretinide group, 30% developed a malignant tumour but there were no benign tumours. Cancer incidences were 61.5% and 10% in the control and combination groups respectively. CONCLUSIONS: Our results showed that the PPAR-gamma ligand rosiglitazone and synthetic retinoid fenretinide have potent chemopreventive properties against in vivo mammary carcinogenesis; however, the efficacies were not enhanced by their combination.