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DRKS00007768; Pre-results.

Endogenous overexpression of the antiapoptotic protein heme oxygenase 1 (HO-1) has been shown to occur in various cancer diseases and might contribute to cancer progression. We compared the expression levels of HO-1 in human liver to expression levels in hepatocellular carcinoma (HCC), as well as the effect of HO-1 inhibition by small interfering RNA (siRNA) on cellular survival and apoptosis in the mouse hepatoma cell lines Hepa129 and Hepa1-6 and on orthotopic tumor growth in immune-competent C3H/HeN mice. Our results show that HO-1 is frequently overexpressed in human HCC. Downmodulation of HO-1 by siRNA resulted in increased cellular damage and apoptosis, reduced proliferation, reduced growth of orthotopic HCC and reduced angiogenesis. Livers and kidneys of treated animals did not reveal signs of damage by this treatment. In conclusion, a specific knockdown of HO-1 might represent a novel therapeutic approach in HCC therapy.

The basic mechanisms underlying calcineurin inhibitor (CI) nephrotoxicity and its enhancement by sirolimus are still largely unknown. We investigated the effects of CIs alone and in combination with sirolimus on the renal proteome and correlated these effects with urine metabolite pattern changes. Thirty-six male Wistar rats were assigned to six treatment groups (n=4/group for proteome analysis and n=6/group for urine 1H-NMR metabolite pattern analysis): vehicle controls, sirolimus 1mg/kg/day, cyclosporine 10mg/kg/day, cyclosporine 10mg/kg/day + sirolimus 1mg/kg/day, tacrolimus 1mg/kg/day, tacrolimus 1mg/kg/day + sirolimus 1mg/kg/day. After 28 days, 24h-urine was collected for 1H-NMR-based metabolic analysis and kidneys were harvested for 2D-gel electrophoresis and histology. Cyclosporine affected the following groups of proteins: calcium homeostasis (regucalcin, calbindin), cytoskeleton (vimentin, caldesmon), response to hypoxia and mitochondrial function (prolyl 4-hydroxylase, proteasome, NADH dehydrogenase) and cell metabolism (kidney aminoacylase, pyruvate dehydrogenase, fructose-1,6-bis phosphate). Several of the changes in protein expression, confirmed by Western blot, were associated with and explained changes in metabolite concentrations in urine. Representative examples are an increase in kidney aminoacylase expression (decrease of hippurate concentrations in urine), up regulation of pyruvate dehydrogenase and fructose-1, 6-bisphosphatase, (increased glucose metabolism) and down regulation of arginine:glycine-amidino transferase (most likely due to an increase in creatinine concentrations). Protein changes explained and qualified immunosuppressant-induced metabolite pattern changes in urine.

Markers of advanced chronic liver disease but not of the severity of acute illness are correlated to ICU outcome in ventilated cirrhotic patients. The outcome of advanced cases (Child-Pugh score of 12 and above) is poor.

Background The clinical use of the immunosuppressant calcineurin inhibitor cyclosporine is limited by its nephrotoxicity. This is enhanced when combined with the immunosuppressive mTOR inhibitor sirolimus. Nephrotoxicity of both drugs is not yet fully understood. Methods The goal was to gain more detailed mechanistic insights into the time-dependent effects of cyclosporine and sirolimus on the rat kidney by using a comprehensive approach including metabolic profiling in urine (1H-NMR spectroscopy), kidney histology, kidney function parameters in plasma, measurement of glomerular filtration rates, the oxidative stress marker 15-F2t-isoprostane in urine and immunosuppressant concentrations in blood and kidney. Male Wistar rats were treated with vehicle (controls), cyclosporine (10/25mg/kg/d) and/or sirolimus (1mg/kg/d) by oral gavage once daily for 6 and 28 days. Results Twenty-eight day treatment led to a decrease of glomerular filtration rates (cyclosporine -59%, sirolimus -25%). These were further decreased when both drugs were combined (-86%). Histology revealed tubular damage after treatment with cyclosporine, which was enhanced when sirolimus was added. No other part of the kidney was affected. 1H-NMR spectroscopy analysis of urine (day 6) revealed time-dependent changes of 2-oxoglutarate, citrate and succinate concentrations. In combination with increased urine isoprostane concentrations these changes indicated oxidative stress. After 28 days of cyclosporine treatment, urine metabonomics shifted to patterns typical for proximal tubular damage with reduction of Krebs cycle intermediates and trimethylamine-N-oxide concentrations whereas acetate, lactate, trimethylamine and glucose concentrations increased. Again, sirolimus enhanced these negative effects. Conclusions Our results indicate that cyclosporine and/or sirolimus induce damage of the renal tubular system. This is reflected by urine metabolite patterns, which seem to be more sensitive than currently used clinical kidney function markers such as creatinine concentrations in serum. Metabolic profiling in urine may provide the basis for the development of toxicodynamic monitoring strategies for immunosuppressant nephrotoxicity.

The interaction between drug-metabolising enzymes and active transporters is an emerging concept in pharmacokinetics. In the gut mucosa, P-glycoprotein and cytochrome P450 (CYP)3A functionally interact in three ways: i) drugs are repeatedly taken up and pumped out of the enterocytes by P-glycoprotein, thus increasing the probability of drugs being metabolised; ii) P-glycoprotein keeps intracellular drug concentrations within the linear range of the metabolising capacity of CYP3A; and iii) P-glycoprotein transports drug metabolites formed in the mucosa back into the gut lumen. In comparison with the gut mucosa, in hepatocytes the spatial sequence of CYP3A and P-glycoprotein is reversed, resulting in different effects when the activity of one or both are changed. CYP3A and P-glycoprotein are both regulated by nuclear receptors such as the pregnane X receptor (PXR). There is significant genetic variability of CYP3A, P-glycoprotein and PXR and their expression and activity is dependent on coadministered drugs, herbs, food, age, hormonal status and disease. Future pharmacogenomic and pharmacokinetic studies will have to take all three components into account to allow for valid conclusions.