RESUMO
BACKGROUND: Fibroadenoma is the most common breast tumor in young women, and its growth and metabolism may be under hormonal control. In the present paper we described the proteoglycan (PG) composition and synthesis rate of normal breast and fibroadenoma during the menstrual cycle. METHODS: Samples of fibroadenoma and adjacent normal breast tissue were obtained at surgery. PGs were characterized by agarose gel electrophoresis and enzymatic degradation with glycosaminoglycan (GAG) lyases, and immunolocalized by confocal microscopy. To assess the synthesis rate, PGs were metabolic labeled by 35S-sulfate. RESULTS: The concentration of PGs in normal breast was higher during the secretory phase. Fibroadenoma contained and synthesized more PGs than their paired controls, but the PG concentrations varied less with the menstrual cycle and, in contrast to normal tissue, peaked in the proliferative phase. The main mammary GAGs are heparan sulfate (HS, 71%-74%) and dermatan sulfate (DS, 26%-29%). The concentrations of both increased in fibroadenoma, but DS increased more, becoming 35%-37% of total. The DS chains contained more ß-d-glucuronic acid (IdoUA/GlcUA ratios were >10 in normal breast and 2-7 in fibroadenoma). The 35S-sulfate incorporation rate revealed that the in vitro synthesis rate of DS was higher than HS. Decorin was present in both tissues, while versican was found only in fibroadenoma. CONCLUSIONS: In normal breast, the PG concentration varied with the menstrual cycle. It was increased in fibroadenoma, especially DS. GENERAL SIGNIFICANCE: PGs are increased in fibroadenoma, but their concentrations may be less sensitive to hormonal control.
