THE INSULIN GROWTH FACTOR-I RECEPTOR EXPRESSION IN RAT MAMMARY CARCINOGENIC PROCESS

SAMBUCO LORENA; RANDI ANDREA; KLEIMAN DE PISAREV DIANA; NÚÑEZ MARIEL; GUTIÉRREZ ALICIA; RIVERA E LENA; MEDINA VANINA; BERGOC ROSA

Rosario, Santa Fe, Argentina

Congreso; XLII Reunión Anual de la Sociedad de Investigación en Bioquímica y Biología Molecular; 2006

SAIB

In previous experiments we demonstrated that three i.p. injections of N-Nitroso-N-methylurea (NMU) at 50, 80 and 110 old of life, induce the development of malignant mammary tumors on normal rats and bening mammary lesions on diabetic ones. The objective of this study was to investigate the expression of the Insulin Growth Factor type-I Receptor (IGF-IR) in mammary gland of diabetic and non-diabetic rats during carcinogenic period.  Four group of rats were radomly separated: a) control (C); b) injected with NMU; c) diabetic rats (STZ); d)diabetic rats injected with NMU (NMU+STZ).  All mammary gland samples were processed at 85, 115 and 145 days. For western blot IGF-IR cuantification, microsomal fraction were separated and immunoblotted with IGF-IR antibody. All samples were also fixed in formalin and tested using anti- IGF-IR specific antibody.  The results indicate that IGF-IR content was significantly increased in NMU rats vs. C ones along the carcinogenic period (P<0.05, Anova and Tukey post-test). Interestingly, NMU+STZ samples at the same times showed a significat lower content of IGF-IR than NMU (P<0.05).  Immunohistochemical results are in concordance with these observations.  The present results correlates with the hypothesis that IGF-IR expression is a crucial factor in malignant transformation and its expression is early modified during mammary carcinogenesis.