Insulin-like Growth Factor-I Receptor expression and localization in diabetic rat mammary tumors

LORENA SAMBUCO; ANDREA RANDI; DIANA KLEIMAN DE PISAREV; ALICIA GUTIÉRREZ; ELENA RIVERA; ACTIS ANDREA; GABRIELA MARTÍN; ROSA BERGOC

Mar del Plata

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

SAIB

The aim of this study was to investigate the expression and localization of the Insulin Growth Factor ? I Receptor (IGF-IR) in mammary glands and tumors of normal and diabetic rats. For tumor induction, three doses of N-Nitroso-N-methylurea (NMU) were injected into rats at 50, 80 and 110 days of age. The diabetic disease of rats were obtained by streptozotocin (STZ) injection at 36 hours of life. Four group of rats were employed: Control (C), STZ, NMU and NMU+STZ. Mammary glands and tumor samples were collected at 140 and 180 days of age for immunohistochemistry and western blot analysis of IGF-IR and RE alfa using specific antibodies. In parallel, specimens were processed for histopathological studies. The results shown: a) at 140 days, IGFI-R levels remained unchanged in STZ vs. C and no differences were found in NMU vs NMU+STZ; however all the tumors had IGF-IR levels higher than C (p< 0.001); b) at 180 days, values changed: IGF-IR levels increased in STZ vs C (p< 0.05) and in NMU+STZ vs. NMU (p< 0.001). The RE alfa content determined at 140 and 180 days was decreased in NMU+STZ vs. NMU (p<0.01). Immunohistochemical results are in concordance with these observations. In conclusion, our observations suggest that IGF-IR level may be involved in the promotion/progression phases of the mammary carcinogenic process.