The Insulin Growth Factor type II Receptor in rat mammary gland tumorigenesis

ALICIA GUTIÉRREZ; LORENA SAMBUCO; MÁXIMO CROCI; MARIEL NÚÑEZ; ELENA RIVERA; ROSA BERGOC; ANDREA RANDI; GABRIELA MARTÍN

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

SAIB

The Insulin-like growth factor II receptor (IGF-IIR) is involved in binding, internalization and degradation of IGF-II. It is now considered to act as a tumor suppressor gene. We have previously demonstrated that three ip injections of N-Nitroso N- Methylurea (NMU) at 50, 80 and 110 days of animals life induce malignant mammary tumors in rats. The aim of the present study, was to investigate the expression of IGF-IIR in mammary tissue of normal (C ) and NMU-injected rats (mNMU) during the carcinogenic process. Also, we studied the IGF-IIR expression in tumors of NMU rats and in those of ovariectomized NMU rats (OVX). Breast tissue specimens were processed at 60, 90, 120, 150 and 180 days. Immunohistochemical and Western blot analysis were performed. Results: there was no significant difference in the intensity of IGF-IIR staining and percentage of positivity were high in normal mammary glands at all times, whilst in mNMU gland the expression lowered progressively between 120 and 180 days. Tumors showed a low cytoplasmatic staining vs mammary tissue. Interestingly, tumors regressing post-OVX showed a low malignant grade and moderate IGF-IIR staining, while tumors that not regressed showed scarce or null receptor expression. Conclusion: our results suggest that decreased levels of IGF-IIR are related to the process of carcinogenesis in this experimental model.