Jornal de Biomarcadores Moleculares e Diagnóstico

Effects of Dietary Fat on Mammary Gland Pyroglutamyl Aminopeptidase on Experimental Breast Cancer

Abstract

María Jesús Ramírez-Expósito, María Dolores Ruíz-Sanjuan and José Manuel Martínez-Martos

Aim: To analyze the relationship between dietary fat and breast cancer mediated by the local functions of gonadotropin-releasing hormone (GnRH), analyzed by its regulating peptidase. The presence of GnRH and its receptors has been demonstrated in tumor tissue of the breast, although the functions of this peptide remain unclear. Pyroglutamyl aminopeptidase (PAP) is the enzyme involved in the local regulation of GnRH, and changes in its soluble and membrane-bound activities have been described in both women with breast cancer and animals with mammary tumors induced by N-methyl nitrosourea (NMU). Methods: We analyze here the effects of different normolipidic (4%) dietary fats (soybean oil (commercial), extra virgin olive oil (EVOO), refined sunflower oil (SO) and refined sunflower oil enriched with 50% oleic acid (OAESO)) on soluble and membrane-bound PAP specific activities in breast tissue of rats with mammary tumors induced by N-methyl-nitrosourea (NMU) administration. Results: We found that animals with breast cancer showed higher levels of soluble PAP than control healthy animals, but in a different degree depending on the type of dietary fat. On the contrary, membrane-bound mammary PAP specific activity was modified only in animals fed on EVOO. Conclusion: Dietary fat is involved in the regulation of GnRH functions mediated by PAP at mammary tumor tissue in different degree depending on its localization and the type of fat administrated.