Antifibrogenic effects of vitamin D derivatives on mouse pancreatic stellate cells

AIM To study the molecular effects of three different D-vitamins, vitamin D2, vitamin D3 and calcipotriol, in pancreatic stellate cells(PSCs).METHODS Quiescent PSCs were isolated from mouse pancreas and activated in vitro by seeding on plastic surfaces. The cells were exposed to D-vitamins as primary cultures(early-activated PSCs) and upon re-culturing(fullyactivated cells). Exhibition of vitamin A-containing lipid droplets was visualized by oil-red staining. Expression of α-smooth muscle actin(α-SMA), a marker of PSC activation, was monitored by immunofluorescence and immunoblot analysis. The rate of DNA synthesis was quantified by 5-bromo-2'-deoxyuridine(Brd U) incorporation assays. Real-time PCR was employed to monitor gene expression, and protein levels of interleukin-6(IL-6) were measured by ELISA. Uptake of proline was determined using 18 F-proline.RESULTS Sustained culture of originally quiescent PSCs inducedcell proliferation, loss of lipid droplets and exhibition of stress fibers, indicating cell activation. When added to PSCs in primary culture, all three D-vitamins diminished expression of α-SMA(to 32%-39% of the level of control cells; P < 0.05) and increased the storage of lipids(scores from 1.97-2.15 on a scale from 0-3; controls: 1.49; P < 0.05). No such effects were observed when D-vitamins were added to fully-activated cells, while incorporation of Brd U remained unaffected under both experimental conditions. Treatment of re-cultured PSCs with D-vitamins was associated with lower expression of IL-6(-42% to-49%; P < 0.05; also confirmed at the protein level) and increased expression of the vitamin D receptor gene(209%-321% vs controls; P < 0.05). There was no effect of D-vitamins on the expression of transforming growth factor-β1 and collagen type 1(chain α1). The lowest uptake of proline, a main component of collagen, was observed in calcipotriol-treated PSCs.CONCLUSION The three D-vitamins inhibit, with similar efficiencies, activation of PSCs in vitro, but cannot reverse the phenotype once the cells are fully activated.

Distinct antifibrogenic effects of erlotinib,sunitinib and sorafenib on rat pancreatic stellate cells

AIM:To study if three clinically available small molecule kinase inhibitors(SMI),erlotinib,sunitinib and sorafenib,exert antifibrogenic effects on pancreatic stellate cells(PSC)and analyze the basis of their action.METHODS:Cultured rat PSC were exposed to SMI.Cell proliferation and viability were assessed employing 5-bromo-2’-deoxyuridine incorporation assay and flow cytometry,respectively.2-Deoxy-2-[18F]fluoroglucose(18F-FDG)uptake was measured to study metabolic activity.Exhibition of the myofibroblastic PSC phenotype was monitored by immunofluorescence analysis ofα-smooth muscle actin(α-SMA)expression.Levels of mRNA were determined by real-time PCR,while protein expression and phosphorylation were analyzed by immunoblotting.Transforming growth factor-β1 (TGF-β1)levels in culture supernatants were quantified by ELISA.RESULTS:All three SMI inhibited cell proliferation and18F-FDG uptake in a dose-dependent manner and without significant cytotoxic effects.Furthermore,additive effects of the drugs were observed.Immunoblot analysis showed that sorafenib and sunitib,but not erlotinib,efficiently blocked activation of the AKT pathway,while all three drugs displayed little effect on phosphorylation of ERK1/2.Cells treated with sorafenib or sunitinib expressed less interleukin-6 mRNA as well as less collagen type 1 mRNA and protein.Sorafenib was the only drug that also upregulated the expression of matrix metalloproteinase-2 and reduced the secretion of TGF-β1 protein.All three drugs showed insignificant or discordant effects on the mRNA and protein levels ofα-SMA.CONCLUSION:The tested SMI,especially sorafenib,exert inhibitory effects on activated PSC,which should be further evaluated in preclinical studies.