Protective effect of resveratrol against LPS-induced extracellular lipoperoxidation in AR42J cells partly via a Myd88-dependent signaling pathway.

Lipopolysaccharides (LPS) are major components of the cell wall of Gram negative bacteria implicated in the pathogenesis of bacterial infection. Resveratrol is a polyphenolic phytoalexin exhibiting antioxidant and anti-inflammatory properties. We investigated the protective effects of this natural compound on LPS-induced proinflammatory effect using non-myeloid AR42J pancreatic cells. We found that LPS dose-dependently increased extracellular malondialdehyde (MDA) and nitric oxide without affecting their intracellular level whereas resveratrol abolished all these deleterious effects. LPS increased CD14 expression; IRAK1 and a phosphorylated form of p38 MAPK protein. Resveratrol counteracted LPS effect by decreasing CD14 and IRAK1 expression but unexpectedly increased the p38 MAPK protein phosphorylation. Altogether, our data highlighted the functionality of the TLR4-Myd88 signaling pathway in LPS pro-oxidant effect using non-myeloid cells. They further suggested that resveratrol exerted antioxidant properties either by a Myd88-dependent way not involving IRAK1 or by a TRIF dependent pathway.

The impact of N- and O-glycosylation on the functions of Glut-1 transporter in human thyroid anaplastic cells.

It has been previously shown that glucose transporter Glut-1 expression was detectable by immunostaining in tissue sections from anaplastic carcinoma, but not in normal thyroid tissue. Using human thyroid anaplastic carcinoma cells, we studied the mechanism by which Glut-1 molecules are translocated from the endoplasmic reticulum to the cell surface. The contribution of N- and O-linked glycans for the translocation and activity of Glut-1 transporter is emphasized. The inhibition of N-glycosylation with tunicamycin (TM) led to a 50% decrease in glucose transport while glycosylated and unglycosylated forms of Glut-1 were found at the cell surface. However, the inhibition of N-linked oligosaccharide processing with deoxymannojirimycin (dMJ) and swainsonine (SW) influenced neither the intracellular trafficking nor the activity of the transporter. On the other hand, Glut-1 bound to the O-linked glycan-specific lectin jacalin and the O-glycosylation inhibitor benzyl-N-acetylgalactosamine dramatically inhibited glucose transport. These results show that O- and N-linked oligosaccharides arbored by Glut-1 are essential for glucose transport in anaplastic carcinoma cells. The quantitative and qualitative alterations of Glut-1 glycosylation and the increase in glucose transport are associated with the anaplastic phenotype of human thyroid cells.

Normal human thyroid cells from the ARAMIS line follow the general concept of growth or differentiation: a study with thyroglobulin as a marker.

A cell line of functional normal human adult thyroid cells was isolated 3 years ago. This cell line was used as a model to study human thyroglobulin (hTgb) production quantified in 5% fetal calf serum Click-RPMI medium and in the presence of insulin and thyrotropin (two hormones [2H]) to get maximal hTgb production. In this paper we demonstrate that these cells (line ARAMIS) follow the general dualistic opposition between growth and differentiation. Thyroglobulin cell production in 2H-stimulated cells is dependent on cell density and is not constant with time of culture in growing and in quiescent cells. High serum levels required for cell proliferation antagonize thyroglobulin cell production. Furthermore, in the absence of cell proliferation, the longer the cells stay in the stationary phase in 2H-medium, the better they produce thyroglobulin with time. The longer the cells stay in the stationary phase in 1H (insulin) medium, the higher will be the total thyroglobulin production and the initial rate in thyroglobulin production after TSH addition. The longer the cells stay in the stationary phase in 1H (insulin) medium, the higher are cyclic adenosine monophosphate (cAMP) levels after thyrotropin (TSH) stimulation. This is observed both for initial rates and total production. Neither insulin nor cell-cell interactions occurring during the stationary phase modify basal cAMP levels. Altogether the data demonstrate that in cell culture conditions that exclude proliferation, a gain in TSH sensitivity appears versus time in insulin-stimulated quiescent normal human thyroid cells during their stationary phase. This improved differentiating status appears to be TSH- and cAMP-independent. It could be an insulin or insulin-like growth factor-1 (IGF-1)-dependent trophic effect promoting an increase in TSH-receptor number or sensitivity. But once again and as mentioned previously, we cannot exclude from the data that cell to cell interactions between silent and "informed" cells (in other words, autocrine phenomena) could result, with time, in the recruitment of silent resting cells, explaining the gain in TSH sensitivity.

Resveratrol increases iodide trapping in the rat thyroid cell line FRTL-5.

BACKGROUND: Resveratrol, a polyphenol found in grapes, exhibits several beneficial health effects by its antioxidant, antiinflammatory, and chemopreventive properties. The aim of the present study was to determine the effect of resveratrol on iodide trapping and efflux as well as its mode of action using FRTL-5 cells, having in mind the pivotal role of the natrium iodide symporter (NIS) in the treatment of differentiated thyroid cancers. METHODS: Cells were treated with resveratrol for various times and doses, in the presence or absence of thyrotropin (TSH). Iodide trapping, iodide efflux, rat NIS (rNIS) protein expression, and cyclic AMP (cAMP) production were evaluated. RESULTS: Resveratrol increased iodide trapping in a time-dependent (optimal 6 hours) and dose-dependent (100 microM) way in the presence of TSH. It showed an additive effect when concomitantly added with an optimal dose of TSH. Resveratrol (50 microM) increased (threefold) rNIS protein expression. In TSH-deprived cells, resveratrol also provoked an increase in rNIS protein (>3-fold in 6 hours) with an optimum at 40 microM. Resveratrol did not inhibit iodide efflux from FRTL-5 cells. It neither increased intracellular cAMP nor induced the arborization of living cells, two TSH-induced effects. A non-cAMP mode of action is highly suspected. CONCLUSIONS: Resveratrol increases iodide trapping in FRTL-5 cells, increasing iodide influx and rNIS protein level even in the absence of TSH. It has an additive effect with TSH. Consequently, resveratrol could be a promising molecule for radioiodide therapy in follicular and papillary differentiated thyroid carcinoma in association with recombinant human TSH.