Effects of gentamicin therapy on urinary excretion of retinol-binding protein, lysozyme and electrolytes

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Effect of aminoglycoside antibiotic therapy on the renal excretion of divalent cations, retinol-binding protein and muramidase

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Exploration of steroselective cleavage of 4, 5-epoycholestane-3, 6-diols and stero controlled epoxidation of cholest-4-en-3 β, 6β-diol-6-acetate

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Selective AKR1C3 inhibitors do not recapitulate the anti-leukaemic activities of the pan-AKR1C inhibitor medroxyprogesterone acetate

Background: We and others have identified the aldo-keto reductase AKR1C3 as a potential drug target in prostate cancer, breast cancer and leukaemia. As a consequence, significant effort is being invested in the development of AKR1C3-selective inhibitors. Methods: We report the screening of an in-house drug library to identify known drugs that selectively inhibit AKR1C3 over the closely related isoforms AKR1C1, 1C2 and 1C4. This screen initially identified tetracycline as a potential AKR1C3-selective inhibitor. However, mass spectrometry and nuclear magnetic resonance studies identified that the active agent was a novel breakdown product (4-methyl(de-dimethylamine)-tetracycline (4-MDDT)). Results: We demonstrate that, although 4-MDDT enters AML cells and inhibits their AKR1C3 activity, it does not recapitulate the anti-leukaemic actions of the pan-AKR1C inhibitor medroxyprogesterone acetate (MPA). Screens of the NCI diversity set and an independently curated small-molecule library identified several additional AKR1C3-selective inhibitors, none of which had the expected anti-leukaemic activity. However, a pan AKR1C, also identified in the NCI diversity set faithfully recapitulated the actions of MPA. Conclusions: In summary, we have identified a novel tetracycline-derived product that provides an excellent lead structure with proven drug-like qualities for the development of AKR1C3 inhibitors. However, our findings suggest that, at least in leukaemia, selective inhibition of AKR1C3 is insufficient to elicit an anticancer effect and that multiple AKR1C inhibition may be required. © 2014 Cancer Research UK. All rights reserved.

Short-chain fatty acid acetate stimulates adipogenesis and mitochondrial biogenesis via GPR43 in brown adipocytes

Short-chain fatty acids play crucial roles in a range of physiological functions. However, the effects of short-chain fatty acids on brown adipose tissue have not been fully investigated. We examined the role of acetate, a short-chain fatty acid formed by fermentation in the gut, in the regulation of brown adipocyte metabolism. Our results show that acetate up-regulates adipocyte protein 2, peroxisomal proliferator-activated receptor-γ coactivator-1α, and uncoupling protein-1 expression and affects the morphological changes of brown adipocytes during adipogenesis. Moreover, an increase in mitochondrial biogenesis was observed after acetate treatment. Acetate also elicited the activation of ERK and cAMP response element-binding protein, and these responses were sensitive to G(i/o)-type G protein inactivator, Gβγ-subunit inhibitor, phospholipase C inhibitor, and MAPK kinase inhibitor, indicating a role for the G(i/o)βγ/phospholipase C/protein kinase C/MAPK kinase signaling pathway in these responses. These effects of acetate were mimicked by treatment with 4-chloro-α-(1-methylethyl)-N-2-thiazolylbenzeneacetamide, a synthetic G protein-coupled receptor 43 (GPR43) agonist and were impaired in GPR43 knockdown cells. Taken together, our results indicate that acetate may have important physiological roles in brown adipocytes through the activation of GPR43.