Vitamin D modifies steroidogenesis and ragulates the expresion of components of the histaminergic system in tumoral Leydig cells

PABLO RENÉ COSTANZO; PIGNATARO, OMAR PEDRO; MARÍA LUISA VARELA; MONDILLO, CAROLINA; PABL, KNOBLOVITS; ABIUSO, ADRIANA MARÍA BELÉN; PABLO SUÁREZ; BESIO MORENO, MARCOS

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencia; 2017

Vitamin D (VD) is a steroid hormone that plays important roles for animal health through the biologically active form 1α,25-dihydroxy-vitamin D3 (calcitriol). VD regulates many physiological functions, such as calcium homeostasis and bone metabolism. Calcitriol binds to nuclear VD receptor (VDR), which is a member of the steroid?thyroid?retinoid receptor family of ligand-activated transcription factors and regulates the expression of target genes via the vitamin D response element (VDRE). VDR is present in most cells in the body and calcitriol directly or indirectly regulates as much as 3?5% of the human genome. Apart from the influence of VD on calcium and phosphate homeostasis, it has been proven that VD is an important modulator of cellular differentiation and proliferation in a num¬ber of normal and malignant cells. In tumor cells, VD can regulate proliferation, apoptosis, and cell ad¬hesion at the cell level. It also modifies tumor angio¬genesis, invasion, and metastasis and decreases oxidative DNA damage. Some observational, preclinical and clinical studies strongly suggest that vitamin D deficiency increases the risk of developing multiple malignancies. Other studies do not support this hypothesis. The incidence of Leydig cell tumor (LCT) has been growing in the last few years. In Argentina, the more affected range of ages is between 11 and 25 years. Although the LCT are commonly benign, in children could appear early puberty and if the tumor became malign in the adult, it does not respond to chemotherapy and radiotherapy. Even though the etiology of LCT is unknown, many studies point to the overexpression of aromatase (CYP19) in tumoral Leydig cells (TLC) and the increase in the synthesis of estradiol (E2), which also stimulates cellular proliferation (CP). Previously we described the proliferative effect of Histamine (HA) and the overexpression of histidine descarboxylase (HDC), the enzyme that produces HA, in TLC R2C. Studies have demonstrated that calcitriol regulates CYP19 expression and activity in numerous cell types, such as human osteoblasts, glioma cells and mesenchymal stem cells. Also, studies have reported that several components of histaminergic system are regulated by calcitriol. These facts underscore the importance of exploring the biology of LCTs, and the need to find new therapeutic targets for its treatment. Although calcitriol treatment has been described for several types of tumors, little is known about its effect, or the presence of VDR, in LCTs.Objective: Analyze the presence of VDR and its regulation by HA and calcitriol. Also, to study the expression of several elements of the histaminergic system as well as steroidogenic variables in TLC R2C, and their modification in presence of different concentrations of calcitriol.Methods: TLC R2C were treated with either calcitriol (10-8 M, 10-9 M, 10-10 M and 10-11M) or HA (10-5 M, 10-6 M, 10-7 M and 10-8 M). The gene expression was measured by RT-qPCR. StAR protein expression was determined by Western blot. Cellular proliferation was measured by 3H-Thymidine incorporation. Results: We observed high expression of HDC, HRH1, HRH2 and HRH4 in TLC R2C exposed to calcitriol 10-9 M (p