BONE ACTIONS OF THE FORGOTTEN ESTROGEN, ESTRONE

CRESCITELLI, M.C.; RAUSCHEMBERGER, M.B.; MASSHEIMER, V.

Buenos Aires

Congreso; LXII Reunión Anual SAIC; 2017

SAIC

Estrogens play an important role in bone remodeling. Althoughestradiol action has been the subject of intensive investigation, littleis known about the contribution of the other major endogenous estrogen,estrone (E1). The aim of this work was to evaluate the effectof E1 on bone cells, particularly the modulation of osteoblasts (OB)maturation. Murine calvarial pre-OB were cultured for 3-15 days andexposed to E1 (10-8 ? 10-10M) in the last 48h. OB characterizationwas performed by the measurement of bone markers, using RTPCRtechnique. mRNA levels for BMP-2 and Runx-2 were detectedin all time of culture (3-15 days). Indeed the expression of both typesof ER (α andβ) was also detected. In 15 days OB culture, E1 significantlyincreased cell proliferation (0,68±0,09 vs 0,49±0,09, E1vs C, p˂0,001 in MTT assay). These results were confirmed by cellcounting (41% above C, p˂0,05). Since mature OB exhibited highlevel of alkaline phosphatase activity (ALP) and enriched extracellularcalcium deposition, we evaluated the effect of E1 on both parameters.E1 enhanced ALP (15% a/C, p< 0,01) and increased thenumber and size of calcification nodules in the extracellular matrix(one fold p˂0,005, Alizarin staining), with major effect at longer periodof cell culture. Accordingly with this, markedly decreased in calciumcontent was detected in aliquots of cultured medium (205±25 vs118±23, C vs E1, p˂0,001). Indeed E1 modulates extracellular collagendeposition visualized by Sirius red staining. On genes relatedwith OB maturation, E1 treatment elicited 2 fold increase in Runx-2mRNA levels, with higher effects at 3-5 days of culture (p