Señalización asociada al receptor del factor de crecimiento similar a la insulina de tipo I en una línea celular colombiana de carcinoma mamario

Abstract

In vitro studies strongly suggest that proliferation, migration and cell survival of breast cancer cell lines are significantly affected by activation of the IGF type 1 receptor (IGF-IR). The phosphorylation by IGF-I of IGF-IR and the intracellular signaling molecules Akt (PI-3K pathway) and Erk1/2 (MAPK pathway) was characterized in a human breast cancer cell lines. The study compared a standard breast adenocarcinoma line (MCF-7) cell line with a line (CSC 1595) derived from an infiltrating ductal breast cancer in a Colombian patient. The CSC 1595 and MCF-7 cell lines were cultured in DMEM supplemented with 10% fetal bovine serum, 2 mM glutamine, 100 U/ml penicillin, and 100 µg/ml streptomycin and grown at 37 °C in 5% CO₂ atmosphere and 95% humidity. Cell extracts were prepared, followed by immunoprecipitation and immunoblotting with specific anti-pIGF-IR, anti-pERK1/2 and anti-pAkt antibodies. After 5 minute stimulation with IGF-I, 70% of the IGF-IR was phosphorylated in the cell line CSC 1595 and 25% in MCF-7. In addition, Akt (oncogene protein v-akt) and ERK1/2 (extracellular signal-regulated MAP kinases) were phosphorylated. Basal and stimulated levels of phosphorylated ERK1/2 were substantially higher compared to those in the MCF-7 cell line. The IGF-IR and MAPK kinase pathway involving proteins ERK1/2 showed more significant phosphorylation in the 1,595 cells compared to the observed in the MCF-7 cell line. Since the IGF-IR is the major activator of this pathway it may play an important role in ductal infiltrating breast cancer tumor growth and metastases.