Curcumin derivatives inhibit testicular 17β-hydroxysteroid dehydrogenase 3

Non-steroidal compounds that inhibit 17β-hydroxysteroid dehydrogenase isoform 3 (17β-HSD3), an enzyme catalyzing the final step in testosterone biosynthesis in Leydig cells, are under development for male contraceptive or treatment of androgen dependent diseases including prostate cancer. A series of curcumin analogues with more stable chemical structures were compared to curcumin as inhibitors of 17β-HSD3 in rat intact Leydig cells as well as rat and human testis microsomes.     

Bystander effects of bioreductive drugs: potential for exploiting pathological tumor hypoxia with dinitrobenzamide mustards

Tumor hypoxia is an important therapeutic target, and it can potentially be exploited by hypoxia-activated prodrugs. However, physiological hypoxia in normal tissues is a limitation. One solution would be to confine activation to severely (pathologically) hypoxic tissue, using hypoxia-activated prodrugs that provide a bystander effect through diffusion of the activated cytotoxin to adjacent regions at intermediate oxygen concentrations (associated with partial radioresistance). To evaluate this requirement, we identified five hypoxia-activated prodrugs with at least 10-fold higher potency against a cell line (A549-P540(puro)) overexpressing human cytochrome P450 reductase (P450R) relative to A549-Lo21 cells with 200-fold lower P450R activity. Bystander killing by these hypoxia-activated prodrugs was tested in anoxic multicellular layer co-cultures of these two cell lines. Cytotoxic potency against A549-Lo21 cells was unaffected by the presence of A549-P450(puro) cells for tirapazamine and RSU-1069 but increased more than 10-fold for the aziridinyldintrobenzamide CB 1954, more than 14-fold for the corresponding nitrogen mustard SN 23862, and 15-fold for its water-soluble analog SN 23816. The cytotoxic extracellular metabolites resulting from hypoxic nitroreduction of CB 1954 and SN 23862 by A549-P450(puro) cells were identified by LC/MS and bioassay methods. For SN 23862, these included the 2-amine metabolite, previously, identified as the bystander metabolite from aerobic activation by the E. coli nfsB nitroreductase, but also novel di-reduced metabolites. Cytotoxicity of SN 23862 to A549-P450(puro) cells was inhibited by lower concentrations of oxygen than for tirapazamine. The combination of selective activation under severe hypoxia with an efficient bystander effect identifies the dinitrobenzamide mustards for further development as hypoxia-activated prodrugs.     

Screening Marine Fungi for Inhibitors of the C4 Plant Enzyme Pyruvate Phosphate Dikinase: Unguinol as a Potential Novel Herbicide Candidate

A total of 2,245 extracts, derived from 449 marine fungi cultivated in five types of media, were screened against the C₄ plant enzyme pyruvate phosphate dikinase (PPDK), a potential herbicide target. Extracts from several fungal isolates selectively inhibited PPDK. Bioassay-guided fractionation of one isolate led to the isolation of the known compound unguinol, which inhibited PPDK with a 50% inhibitory concentration of 42.3 ± 0.8 μM. Further kinetic analysis revealed that unguinol was a mixed noncompetitive inhibitor of PPDK with respect to the substrates pyruvate and ATP and an uncompetitive inhibitor of PPDK with respect to phosphate. Unguinol had deleterious effects on a model C₄ plant but no effect on a model C₃ plant. These results indicate that unguinol inhibits PPDK via a novel mechanism of action which also translates to an herbicidal effect on whole plants.     

Lack of association between common polymorphisms in the 17beta-hydroxysteroid dehydrogenase type V gene (HSD17B5) and precocious pubarche

BACKGROUND: 17beta-Hydroxysteroid dehydrogenase (type V; HSD17B5) is a key enzyme involved in testosterone production in females. A single nucleotide polymorphism (SNP) in the promoter region of its gene was recently found to be associated with polycystic ovary syndrome (PCOS) and its related hyperandrogenaemia. Precocious pubarche (PP) is a clinical entity pointing to adrenal androgen excess from mid-childhood onward and is associated with ovarian androgen excess from puberty onward. It is therefore a strong risk factor for PCOS. METHODS: To investigate associations between this promoter SNP along with three exonic SNPs (one non-synonymous and two synonymous) from the same gene, and PP, a case-control study was performed in 190 girls with PP (84 of which were also tested for functional ovarian hyperandrogenism) from Barcelona, Spain and 71 healthy controls. Clinical features and hormone concentrations relevant to hyperandrogenism were compared by HSD17B5 genotype and haplotype. RESULTS: Neither HSD17B5 genotypes nor haplotype were associated with PP, or subsequent androgen excess in girls from Barcelona (all P>0.05). CONCLUSIONS: HSD17B5 SNPs predicted to have functional effects do not appear to be a risk factor for PP in girls from Barcelona, despite these girls being at high risk of developing androgen excess in adulthood.     

Dominance of the alpha1B-adrenergic receptor and its subcellular localization in human and TRAMP prostate cancer cell lines

The function and distribution of alpha1-adrenergic receptor (AR) subtypes in prostate cancer cells is well characterized. Previous studies have used RNA localization or low-avidity antibodies in tissue or cell lines to determine the alpha1-AR subtype and suggested that the alpha1A-AR is dominant. Two androgen-insensitive, human metastatic cancer cell lines DU145 and PC3 were used as well as the mouse TRAMP C1-C3 primary and clonal cell lines. The density of alpha1-ARs was determined by saturation binding and the distribution of the different alpha1-AR subtypes was examined by competition-binding experiments. In contrast to previous studies, the major alpha1-AR subtype in DU145, PC3 and all of the TRAMP cell lines is the alpha1B-AR. DU145 cells contained 100% of the alpha1B-AR subtype, whereas PC3 cells were composed of 21% alpha1 A-AR and 79% alpha1B-AR. TRAMP cell lines contained between 66% and 79% of the alpha1B-AR with minor fractions of the other two subtypes. Faster doubling time in the TRAMP cell lines correlated with decreasing alpha 1B-AR and increasing alpha1 A- and alpha1D-AR densities. Transfection with EGFP-tagged alpha1B-ARs revealed that localization was mainly intracellular, but the majority of the receptors translocated to the cell surface after extended preincubation (18 hr) with either agonist or antagonist. Localization was confirmed by ligand-binding studies and inositol phosphate assays where prolonged preincubation with either agonist and/or antagonist increased the density and function of alpha 1-ARs, suggesting that the native receptors were mostly intracellular and nonfunctional. Our studies indicate that alpha1B-ARs are the major alpha1-AR subtype expressed in DU145, PC3, and all TRAMP cell lines, but most of the receptor is localized in intracellular compartments in a nonfunctional state, which can be rescued upon prolonged incubation with any ligand.     

The early evolution of land plants,from fossils to genomics: a commentary on Lang (1937) ‘On the plant-remains from the Downtonian of England and Wales'

During the 1920s, the botanist W. H. Lang set out to collect and investigate some very unpromising fossils of uncertain affinity, which predated the known geological record of life on land. His discoveries led to a landmark publication in 1937, ‘On the plant-remains from the Downtonian of England and Wales’, in which he revealed a diversity of small fossil organisms of great simplicity that shed light on the nature of the earliest known land plants. These and subsequent discoveries have taken on new relevance as botanists seek to understand the plant genome and the early evolution of fundamental organ systems. Also, our developing knowledge of the composition of early land-based ecosystems and the interactions among their various components is contributing to our understanding of how life on land affects key Earth Systems (e.g. carbon cycle). The emerging paradigm is one of early life on land dominated by microbes, small bryophyte-like organisms and lichens. Collectively called cryptogamic covers, these are comparable with those that dominate certain ecosystems today. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society.