The extracellular matrix (ECM) promotes the differentiation of many cell types, and ECM remodeling in the liver has been implicated in embryonic development, tissue injury, and oncogenesis. Integrins are heterodimeric ECM receptors that play critical roles in transducing the composition of the ECM in the cell environment. We previously showed that mouse H2.35 cells, a conditionally transformed, liver-derived cell line, assume a more differentiated hepatocyte morphology and enhanced liver-specific gene expression when the cells are cultured on gelatinous ECM substrata. Here we show that H2.35 cells express relatively high levels of ␣ 3 ␤ 1 -integrins, similar to that previously shown for immature hepatocytes, transformed hepatocytes, and biliary cells. However, the cell morphological responses that depend on ␣ 3 ␤ 1 -integrin have not been defined. We found that transfecting H2.35 cells with antisense RNA construct directed to ␣ 3 -subunit messenger RNA perturbs the initial cell attachment to laminin and collagen, and strongly inhibits cell morphological, proliferative, and gene expression responses to a collagen gel substratum. In situ hybridization to mouse embryo tissues demonstrates the presence of ␣ 3 -subunit messenger RNAs in newly formed hepatocytes. We suggest that ␣ 3 ␤ 1 -integrins are important for immature and transformed hepatocytes to respond morphologically to the extracellular matrix. (HEPATOLOGY 1998;28:1095-1104.)Tissue-specific gene expression, morphogenesis, and cell migration are promoted by interactions between cells and the surrounding extracellular matrix (ECM). For example, early hepatocyte differentiation begins as foregut endodermal cells enter the new collagenous environment of the surrounding mesenchyme, 1 and the role of the ECM in adult hepatocyte differentiation is well established. [2][3][4][5][6][7][8] Other examples of ECMpromoted differentiation include the differentiation of keratinocytes, 9 gastrulation in Pleurodeles embryos, 10 and the epithelial conversion of kidney mesenchyme 11 (for review, see Adams and Watt 12 ). The ECM is present in all animals from the earliest stages of development and is composed of a mixture of proteins and proteoglycans such as collagens, laminin, and fibronectin. An important set of membrane receptors for ECM molecules is the integrin family of proteins. [13][14][15] Integrins are heterodimers of ␣ and ␤ subunits, with each subunit containing an N-terminal extracellular domain, a transmembrane domain, and a C-terminal intracellular domain. Integrins activate common as well as subgroupspecific intracellular signaling pathways in response to the ECM. 16,17 Membrane proximal events triggered by integrin ligation include the activation of the focal adhesion kinase 18 by the ␤ subunit and the recruitment of adapter protein Shc by certain ␣ subunits within heterodimers. 19 More ␣ subunits are known than ␤ subunits, and the particular combination of ␣ and ␤ partners determines the ligand specificity for ECM molecules. An ECM protein can be recognized...

Background The Rio Doce estuary, in Brazil, was impacted by the deposition of iron mine tailings, caused by the collapse of a dam in 2015. Based on published baseline datasets, the estuary has been experiencing chronic trace metal contamination effects since 2017, with potential bioaccumulation in fishes and human health risks. As metal and metalloid concentrations in aquatic ecosystems pose severe threats to the aquatic biota, we hypothesized that the trace metals in estuarine sediments nearly two years after the disaster would lead to bioaccumulation in demersal fishes and result in the biosynthesis of metal-responsive proteins. Methods We measured As, Cd, Cr, Cu, Fe, Mn, Pb, Se and Zn concentrations in sediment samples in August 2017 and compared to published baseline levels. Also, trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se and Zn) and protein (metallothionein and reduced glutathione) concentrations were quantified in the liver and muscle tissues of five fish species (Cathorops spixii, Genidens genidens, Eugerres brasilianus, Diapterus rhombeus and Mugil sp.) from the estuary, commonly used as food sources by local populations. Results Our results revealed high trace metal concentrations in estuarine sediments, when compared to published baseline values for the same estuary. The demersal fish species C. spixii and G. genidens had the highest concentrations of As, Cr, Mn, Hg, and Se in both, hepatic and muscle, tissues. Trace metal bioaccumulation in fish was correlated with the biosynthesis of metallothionein and reduced glutathione in both, liver and muscle, tissues, suggesting active physiological responses to contamination sources. The trace metal concentrations determined in fish tissues were also present in the estuarine sediments at the time of this study. Some elements had concentrations above the maximum permissible limits for human consumption in fish muscles (e.g., As, Cr, Mn, Se and Zn), suggesting potential human health risks that require further studies. Our study supports the high biogeochemical mobility of toxic elements between sediments and the bottom-dwelling biota in estuarine ecosystems.

The first‐line chemotherapy treatment for Glioblastoma (GBM) ‐ the most aggressive and frequent brain tumor ‐ is temozolomide (TMZ). The Sonic hedgehog (SHH) pathway is involved with GBM tumorigenesis and TMZ chemoresistance. The role of SHH pathway inhibition in the potentiation of TMZ's effects using T98G, U251, and GBM11 cell lines is investigated herein. The combination of GANT‐61 and TMZ over 72 hr suggested a synergistic effect. All TMZ‐resistant cell lines displayed a significant decrease in cell viability, increased DNA fragmentation and loss of membrane integrity. For T98G cells, G2/M arrest was observed, while U251 cells presented a significant increase in reactive oxygen species production and catalase activity. All the cell lines presented acidic vesicles formation correlated to Beclin‐1 overexpression. The combined treatment also enhanced GLI1 expression, indicating the presence of select resistant cells. The selective inhibition of the SHH pathway potentiated the cytotoxic effect of TMZ, thus becoming a promising in vitro strategy for GBM treatment.

No abstract

No abstract

AbstractThe Rio Doce estuary in Brazil was impacted by the deposition of mine tailings caused by the collapse of a mining dam in 2015. Since the disaster, the estuary is experiencing chronic trace metal contamination effects, but potential trace metal accumulation in fishes has not been reported. Trace metals in aquatic ecosystems pose severe threats to the aquatic biota, so we hypothesized that the accumulation of trace metals in estuarine sediments nearly two years after the disaster would cause contaminant bioaccumulation, resulting in the biosynthesis of metal-responsive proteins in fishes. We determined trace metal concentrations in sediment samples, metal concentrations, and quantified stress protein concentrations in the liver and muscle tissue of five different fish species in the estuary. Our results revealed high concentrations of trace metals in estuarine sediments when compared to published baseline values for this estuary. The demersal fish species Cathorops spixii and Genidens genidens had the highest Hg, As, Se, Cr, and Mn concentrations in both hepatic and muscle tissues. Metal bioaccumulation in fish was statistically correlated with the biosynthesis of metallothionein and reduced glutathione in both fish liver and muscle tissue. The trace metals detected in fish tissues resemble those in the contaminated sediments present at the estuary at the time of this study and were also significantly correlated to protein levels. Trace metals in fish muscle were above the maximum permissible limits for human consumption, suggesting potential human health risks that require further determination. Our study supports the high biogeochemical mobility of trace metals between contaminated sediments and local biota in estuarine ecosystems.

No abstract

Poultry litter is widely applied as a fertilizer even though it is one of the main antibiotic sources for agricultural soils. Long-term sublethal effects (56 days) on the antioxidant system of Eisenia andrei earthworms following exposure to uoroquinolone-contaminated poultry litter (enro oxacin + cipro oxacin) at 5.0, 10 and 20 g kg -1 were evaluated. The following biomarkers were assessed: superoxide dismutase (SOD), catalase (CAT), glutathione-S-trasferase (GST), reduced glutathione (GSH) and a lipid peroxidation (LPO) proxy. Signi cant CAT and SOD increases and a moderate positive correlation (ρ = 0.67, p < 0.05) between these enzymes was observed. Glutathione-S-trasferase levels increased signi cantly at 10 g kg -1 , while GSH exhibited a dose-dependent response at 5.0 mg kg -1 (4 -106%), 10 mg kg -1 (28 -330 %) and 20 mg kg -1 (45 -472%). LPO levels exhibited a decreasing trend with increasing poultry litter concentrations of 8 -170% (5.0 g kg -1 ), 7 -104% (10 mg kg -1 ) and 3 -6% (20 mg kg -1 ). A Principal Component Analysis (PCA) highlighted increased SOD and CAT activities, possibly due to increases in reactive oxygen species (ROS) concentrations. Biological Health Status assessments based on the Biomarker Response Index indicate major alterations in the rst month of exposure, changing to moderate in the second month. These ndings indicate an antioxidant system attenuation trend. It is possible, however, that successive poultry litter applications may reduce the long-term recovery capacity of the evaluated biomarkers.