Deregulation of E2F1 activity and resistance to TGFbeta are hallmarks of gastric cancer. MicroRNAs (miRNAs) are small noncoding RNAs frequently misregulated in human malignancies. Here we provide evidence that the miR-106b-25 cluster, upregulated in a subset of human gastric tumors, is activated by E2F1 in parallel with its host gene, Mcm7. In turn, miR-106b and miR-93 regulate E2F1 expression, establishing a miRNA-directed negative feedback loop. Furthermore, upregulation of these miRNAs impairs the TGFbeta tumor suppressor pathway, interfering with the expression of CDKN1A (p21(Waf1/Cip1)) and BCL2L11 (Bim). Together, these results suggest that the miR-106b-25 cluster is involved in E2F1 posttranscriptional regulation and may play a key role in the development of TGFbeta resistance in gastric cancer.

Human monocytes cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-13 for 7 days differentiate into cells with the morphology and function of dend-ritic cells (DC). We have investigated the effect of IL-10 on this differentiation pathway. In the presence of IL-10 cells did not develop DC morphology, did not express CD1a and had lower levels of MHC class II. IL-10 promoted the differentiation of large cells with the morphology , cytochemistry and membrane phenotype of macrophages, including staining for nonspecific esterase and high levels of CD14, CD16 and CD68. The effect of IL-10 was dose dependent and was best appreciated when the cytokine was added at the initiation of the culture, as addition on day 3 was less inhibitory. When added to already differentiated DC on day 6, IL-10 caused only a modest reduction of MHC class II and CD1a expression, and no acquisition of the macrophage markers CD14, CD16 and CD68. Prolonged incubation up to 5 days with IL-10 did not induce a shift of differentiated DC to macrophages. On the other hand, the macrophages obtained by culturing for 7 days with GM-CSF+IL-13+IL-10 did not shift to DC upon removal of IL-10 for up to 3 days. Thus, the effect of IL-10 on monocyte differentiation , occurs only at the precursor level and confers an irreversible phenotype. From a functional point of view, cells cultured in the presence of IL-10 were poor stimulators of allogeneic cord blood T cells in mixed lymphocyte reaction (MLR) and presented tetanus toxin (TT) to specific T cell lines with much less efficiency than control DC. In contrast, IL-10-cultured DC showed 7 times greater endocytosis of FITC-dextran. This increased endocyto-sis was mostly mediated via the mannose receptor, as demonstrated by blocking with unla-beled mannose. In conclusion, IL-10 inhibits DC differentiation from monocytes and, in a substantial proportion of the cells, promotes the differentiation to mature macrophages. Intriguingly, IL-10 inhibits antigen presentation while it stimulates endocytic activity.

The up-regulation of "tissue" transglutaminase (TG2) gene has been shown to occur in various pathologies and can lead to severe liver injury; however, its role in the onset of liver damage has not yet been clarified. To address this issue, we have used two experimental settings: carbon tetrachloride (CCl(4))-induced liver injury in wild-type and TG2 knockout mice; and liver biopsies obtained from a large cohort of hepatitis C virus (HCV)-infected patients. Mice lacking TG2 failed to clear the hepatic necrotic tissue formed in response to prolonged CCl(4) exposure (5 weeks) and 60% of them died before the end of the treatment. By contrast, wild-type mice were able to recover after the toxic insult. CCl(4)-treated TG2 null mice showed a derangement of the hepatic lobular architecture and a progressive accumulation of extracellular matrix (ECM) components and inflammatory cells which were not observed in the liver of control animals. Consistent with this protective role, we observed that TG2 levels were much higher (up to 15-fold) during the initial stages of liver fibrosis in HCV-infected individuals (METAVIR = F2) compared with uninfected controls, in which the enzyme protein localized in the hepatocytes facing the periportal infiltrate. By contrast, the enzyme levels decreased in the advanced stages (METAVIR = F3 and F4) and their localization was limited to the ECM. Our data demonstrate that TG2 plays a protective role in the liver injury by favoring tissue stability and repair.

534R enal vascular and parenchymal lesions represent a common target organ damage in hypertension.1,2 Clinical studies show that blood pressure (BP) lowering reduces renal damage and progression to renal failure. 3 Previous studies focused on the role of high-BP levels, abnormalities of the renin-angiotensin system, and excess of dietary salt intake as important factors contributing to pathogenesis of renal lesions associated to hypertension in both animal models and humans. 4 In the stroke-prone spontaneously hypertensive rat (SHRsp), renal vascular and tissue lesions develop after only 4 weeks of high-salt/low-potassium (HS) Japanese-style diet. In contrast, in spite of similar BP levels at 4 weeks, the parental strain strictly related to SHRsp (stroke-resistant SHR [SHRsr]) displays a much lesser degree of renal damage. 5 In the SHRsp, renal lesions precede the development of cerebrovascular lesions suggesting common underlying etiopathogenetic mechanisms. 6HS diet enhances vascular oxidant stress leading to vascular dysfunction.7 Of note, the mitochondrion has emerged as a major source of reactive oxygen species (ROS) in the vasculature. 8 Within the mitochondria, uncoupling protein 2 (UCP2) has recently been reported as a negative regulator of ROS generation.9 Its ablation leads to marked increase of oxidative stress in several cell types.10 Moreover, lack of UCP2 exacerbates HS-induced vascular dysfunction in salt-loaded mice. 11 UCP2 genetic variants have been associated to predisposition to renal damage development in humans. 12,13 In the present study, we investigated whether a dysfunctional UCP2 is associated with increased renal vascular damage in SHRsp. Based on the identification of lower UCP2 expression only in the kidneys of SHRsp under HS diet, we explored the in vitro functional impact of UCP2 downregulation on ROS production, inflammation, apoptosis, and necrosis in rat renal mesangial cells. Finally, we attempted to identify Abstract-The stroke-prone spontaneously hypertensive rat (SHRsp) represents an animal model of increased susceptibility to high-salt diet-induced cerebral and renal vascular injuries. High blood pressure and genetic factors are viewed as major contributing factors. In high-salt-loaded SHRsp and stroke-resistant SHR animals, we determined blood pressure levels, degree of kidney lesions, renal uncoupling protein 2 (UCP2) gene and protein expression levels along with rattus norvegicus (rno)-microRNA (miR) 24 and 34a gene expression, nuclear factor-κB protein levels, and oxidative stress. In vitro, UCP2 gene silencing was performed in renal mesangial cells. We found more severe degree of renal damage in SHRsp at the end of 4-week high-salt dietary treatment as compared with stroke-resistant SHR, despite comparable blood pressure levels, along with increased rate of inflammation and oxidative stress. Kidney UCP2 gene and protein expression levels were significantly downregulated under high-salt diet in SHRsp, but not in stroke-resistant SHR. Differential UCP2 regulation was par...

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