Objective: The pleiotropic effect of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) is responsible for potent defense against inflammatory response. This study evaluated the inhibitory effects of HMG-CoA reductase inhibitors on monosodium urate (MSU)-induced inflammatory response through the regulation of interleukin-37 (IL-37) expression. Methods: Serum was collected from patients with gout (n = 40) and from healthy controls (n = 30). The mRNA and protein expression of target molecules IL-1b, IL-37, caspase-1, and Smad3 was measured in THP-1 cells stimulated with MSU, atorvastatin, or rosuvastatin using real-time quantitative polymerase chain reaction and Western blot assay. Transfection with IL-1b or Smad3 siRNA in THP-1 cells was used to verify the pharmaceutical effect of statins in uric acid-induced inflammation. Results: Serum IL-37 level in gout patients was significantly higher than in controls (p < 0.001) and was associated with serum uric acid level (r = 0.382, p = 0.008). THP-1 cells stimulated with MSU markedly induced IL-37 mRNA expression and transition of IL-37 from cytoplasm to nucleus. Recombinant IL-37 treatment dose-dependently inhibited activation of caspase-1 and IL-1b in MSU-induced inflammation. Atorvastatin and rosuvastatin attenuated caspase-1 activation and mature IL-1b expression but augmented translocation of IL-37 from cytoplasm to nucleus. Atorvastatin and rosuvastatin induced phosphorylation of Smad3 in THP-1 cells treated with MSU crystals. Statins potently attenuated translocation of IL-37 from cytoplasm to nucleus in THP-1 cells transfected with Smad3 siRNA compared to cells with negative control siRNA. Conclusion: This study revealed that statins inhibit MSU-induced inflammatory response through augmentation of phosphorylated Smad3-mediated IL-37 expression in THP-1 cells.

Abstract: The transforming growth factor beta (TGFβ) and Hippo signaling pathways are evolutionarily conserved pathways that play a critical role in cardiac fibroblasts during embryonic development, tissue repair, and fibrosis. TGFβ and Hippo signaling is also important for cardiac cushion remodeling and septation during embryonic development. Loss of TGFβ2 in mice causes cardiac cushion remodeling defects resulting in congenital heart disease. In this study, we used in vitro molecular and pharmacologic approaches in the cushion mesenchymal cell line (tsA58-AVM) and investigated if Hippo pathway acts as a mediator of TGFβ2 signaling. Immunofluorescence staining showed that TGFβ2 induced nuclear translocation of activated SMAD3 in the cushion mesenchymal cells. In addition, the results indicated increased nuclear localization of Yes associated protein 1 (YAP1) following a similar treatment of TGFβ2. In collagen lattice formation assays, TGFβ2 treatment of cushion cells resulted in an enhanced collagen contraction compared to the untreated cushion cells. Interestingly, verteporfin, a YAP1 inhibitor, significantly blocked the ability of cushion cells to contract collagen gel in absence or presence of by exogenously added TGFβ2. To confirm the molecular mechanisms of verteporfin induced inhibition of TGFβ2-dependent extra-cellular matrix (ECM) reorganization we performed gene expression analysis of key mesenchymal genes involved in ECM remodeling in heart development and disease. Our results confirmed that verteporfin significantly decreased the expression of α-smooth muscle actin (Acta2), collagen 1a1 (Col1a1), Ccn1 (i.e., Cyr61), and Ccn2 (i.e., Ctgf). Western blot analysis indicated that verteporfin treatment significantly blocked TGFβ2-induced activation of SMAD2/3 in cushion mesenchymal cells. Collectively, these results indicate that TGFβ2 regulation of cushion mesenchymal cell be-havior and ECM remodeling is mediated by YAP1. Thus, TGFβ2 and Hippo pathway integration represents an important step in understanding the etiology of congenital heart disease.

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease due to early metastatic spread, late diagnosis and the lack of efficient therapies. A major driver of cancer progression and hurdle to successful treatment is the desmoplastic reaction of the tumor stroma, the formation of which is orchestrated by transforming growth factor (TGF)-β. Recent data from pancreatic cancer mouse models have shown that the TGF-β pathway is controlled by transcriptionally active p73 (TAp73) through secretion of biglycan (Bgn) via intermittent expression of the TGF-β signaling intermediates, Smad3 and Smad4. Genetic knockout of TP73, and, as a consequence, deficient induction of Smad3/Dpc4 and secretion of Bgn led to activation of TGF-β signaling through a (Smad-independent) ERK pathway, favoring epithelial-mesenchymal transition (EMT) and cell motility. Except for BGN, these functions of TAp73 have recently been shown to also operate in human PDAC cells and are reminiscent of what we previously observed for the small GTPase, RAC1b. This prompted us to hypothesize that TAp73 and RAC1b are part of the same tumor-suppressive pathway in human PDAC cells. The two objectives of this study, therefore, were to reveal i) if the regulatory interactions between TAp73 and Bgn previously discovered in murine PDAC-derived cells also operate in their human counterparts, and ii) if RAC1b collaborates with TAp73 in these tumor-suppressive activities in human PDAC cells. Using a variety of experimental approaches, including mutual rescue experiments, we were able to show that the previously proposed tumor-suppressive TAp73-Smad4-Bgn signaling also operates in human cells and that RAC1b is as an upstream activator of this pathway. Our findings highlight the complex role of TGF-β in pancreatic tumorigenesis and might have implications for therapeutic approaches targeting this growth factor for inhibition.