ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2016) 41 OC8.2 | DOI: 10.1530/endoabs.41.OC8.2

Selenium modulates apoptosis in thyroid follicular cells: characterization of molecular mechanisms

Immacolata Cristina Nettore1, Luigi Maione1, Carmela Passaro2, Claudia Pivonello1, Mariarosaria Negri1, Silvio Desiderio1, Emma De Nisco1, Rosario Pivonello1, Paola Ungaro3, Giuseppe Portella2, Annamaria Colao1 & Paolo Emidio Macchia1

1Dipartimento di Medicina Clinica e Chirurgia, Università degli studi di Napoli “Federico II”, Naples, Italy; 2Dipartimento di Scienze Mediche Traslazionali, Università degli Studi di Napoli “Federico II”, Naples, Italy; 3Istituto di Endocrinologia ed Oncologia Sperimentale del CNR (IEOS-CNR) “G. Salvatore”, Naples, Italy.

: Inflammation and several oxidative processes are modulated by Selenium (Se) trough the selenoproteins. Se deficiency has been associated with thyroid autoimmune diseases and hypothyroidism, while Se-supplementation reduces antibodies titles and ameliorates ultrasound pattern of the gland.

Aim of the current study, is to study the molecular effects of Se-supplementation in thyroid follicular cells (FRTL5).

FRTL5 cells have been starved and treated with or without 100 nM Sodium-Selenite (Na-Se). In comparison to the untreated cells, the number of Se-supplemented cells is higher and mortality is reduced as demonstrated by Fluorescence-activated Cells Sorting (FACS) analysis. The maximum effect is present 48 h after the beginning of the treatment. Moreover, after 72 h of Na-Se treatment, cell proliferation improves, as demonstrated by DNA content measured by bisbenzimide fluorescent dye (Hoechst 33258).

Real-time qPCR performed from 12 to 96 h after Se-treatment demonstrate a reduced expression of pro-apoptotic genes (Casp8ap2, Bcl2l11) starting from 24 h and over-expression of anti-apoptotic genes (Bcl2, Bcl2l1, Dapk1 and NFKB1) starting from 48 h.

Next, the anti-apoptotic role of Se has been tested in FRTL5 cells pre-treated with tunicamycin, an inhibitor of N-linked glycosylation that induces apoptosis via ER-stress. In detail, FRTL5 were incubated for 24 hours with 2 μg/ml of tunicamycin (TN) with or without a 72–96 h 500 nM of Na-Se pre-treatment. Cell viability (measured by MTT) is higher (P<0.05) in Na-Se pre-treated cells compared to cells incubated with tunicamycin alone, and Western Blot confirmed a reduced Poly- (ADP-ribose) polymerase (PARP) cleavage at 96 hrs of combined treatment.

This is the first report directly demonstrating a specific effect of Se on apoptosis modulation in normal thyroid follicular cells. Our data provide a molecular explanation for clinical improvement observed after treatment with Se in patients with autoimmune thyroid disease.