Promising Tools in Prostate Cancer Research:Selective Non-Steroidal Cytochrome P450 17A1 Inhibitors

Cytochrome P450 17A1 (CYP17A1) is an important target in the treatment of prostate cancer because it produces androgens required for tumour growth. The FDA has approved only one CYP17A1 inhibitor, abiraterone, which contains a steroidal scaffold similar to the endogenous CYP17A1 substrates. Abiraterone is structurally similar to the substrates of other cytochrome P450 enzymes involved in steroidogenesis, and interference can pose a liability in terms of side effects. Using non-steroidal scaffolds is expected to enable the design of compounds that interact more selectively with CYP17A1. Therefore, we combined a structure-based virtual screening approach with density functional theory (DFT) calculations to suggest non-steroidal compounds selective for CYP17A1. In vitro assays demonstrated that two such compounds selectively inhibited CYP17A1 17α-hydroxylase and 17,20-lyase activities with IC(50) values in the nanomolar range, without affinity for the major drug-metabolizing CYP2D6 and CYP3A4 enzymes and CYP21A2, with the latter result confirmed in human H295R cells

Surgery of non-spinal skeletal metastases in renal cell carcinoma

Background and purpose - Surgery for metastases of renal cell carcinoma has increased in the last decade. It carries a risk of massive blood loss, as tumors are hypervascular and the surgery is often extensive. Preoperative embolization is believed to facilitate surgery. We evaluated the effect of preoperative embolization and resection margin on intraoperative blood loss, operation time, and survival in non-spinal skeletal metastases of renal cell carcinoma. Patients and methods - This retrospective study involved 144 patients, 56 of which were treated preoperatively with embolization. The primary outcome was intraoperative blood loss. We also identified factors affecting operating time and survival. Results - We did not find statistically significant effects on intraoperative blood loss of preoperative embolization of skeletal non-spinal metastases. Pelvic localization and large tumor size increased intraoperative blood loss. Marginal resection compared to intralesional resection, nephrectomy, level of hemoglobin, and solitary metastases were associated with better survival. Interpretation - Tumor size, but not embolization, was an independent factor for intraoperative blood loss. Marginal resection rather than intralesional resection should be the gold standard treatment for skeletal metastases in non-spinal renal cell carcinoma, especially in the case of a solitary lesion, as this improved the overall survival.Peer reviewe

A new class of IMP dehydrogenase with a role in self-resistance of mycophenolic acid producing fungi

<p>Abstract</p> <p>Background</p> <p>Many secondary metabolites produced by filamentous fungi have potent biological activities, to which the producer organism must be resistant. An example of pharmaceutical interest is mycophenolic acid (MPA), an immunosuppressant molecule produced by several <it>Penicillium </it>species. The target of MPA is inosine-5'-monophosphate dehydrogenase (IMPDH), which catalyses the rate limiting step in the synthesis of guanine nucleotides. The recent discovery of the MPA biosynthetic gene cluster from <it>Penicillium brevicompactum </it>revealed an extra copy of the IMPDH-encoding gene (<it>mpaF</it>) embedded within the cluster. This finding suggests that the key component of MPA self resistance is likely based on the IMPDH encoded by <it>mpaF</it>.</p> <p>Results</p> <p>In accordance with our hypothesis, heterologous expression of <it>mpaF </it>dramatically increased MPA resistance in a model fungus, <it>Aspergillus nidulans</it>, which does not produce MPA. The growth of an <it>A. nidulans </it>strain expressing <it>mpaF </it>was only marginally affected by MPA at concentrations as high as 200 μg/ml. To further substantiate the role of <it>mpaF </it>in MPA resistance, we searched for <it>mpaF </it>orthologs in six MPA producer/non-producer strains from <it>Penicillium </it>subgenus <it>Penicillium</it>. All six strains were found to hold two copies of IMPDH. A cladistic analysis based on the corresponding cDNA sequences revealed a novel group constituting <it>mpaF </it>homologs. Interestingly, a conserved tyrosine residue in the original class of IMPDHs is replaced by a phenylalanine residue in the new IMPDH class.</p> <p>Conclusions</p> <p>We identified a novel variant of the IMPDH-encoding gene in six different strains from <it>Penicillium </it>subgenus <it>Penicillium</it>. The novel IMPDH variant from MPA producer <it>P. brevicompactum </it>was shown to confer a high degree of MPA resistance when expressed in a non-producer fungus. Our study provides a basis for understanding the molecular mechanism of MPA resistance and has relevance for biotechnological and pharmaceutical applications.</p

Advancing uracil-excision based cloning towards an ideal technique for cloning PCR fragments

The largely unused uracil-excision molecular cloning technique has excellent features in most aspects compared to other modern cloning techniques. Its application has, however, been hampered by incompatibility with proof-reading DNA polymerases. We have advanced the technique by identifying PfuCx as a compatible proof-reading DNA polymerase and by developing an improved vector design strategy. The original features of the technique, namely simplicity, speed, high efficiency and low cost are thus combined with high fidelity as well as a transparent, simple and flexible vector design. A comprehensive set of vectors has been constructed covering a wide range of different applications and their functionality has been confirmed

Adaptive evolution of drug targets in producer and non-producer organisms

Mycophenolic acid (MPA) is an immunosuppressive drug produced by several fungi in Penicillium subgenus Penicillium. This toxic metabolite is an inhibitor of IMP dehydrogenase (IMPDH). The MPA biosynthetic cluster of P. brevicompactum contains a gene encoding a B-type IMPDH, IMPDH-B, which confers MPA-resistance. Surprisingly, all members of subgenus Penicillium contain genes encoding IMPDHs of both the A and B type, regardless of their ability to produce MPA. Duplication of the IMPDH gene occurred prior to and independent of the acquisition of the MPA biosynthetic cluster. Both P. brevicompactum IMPDHs are MPA-resistant while the IMPDHs from a nonproducer are MPA-sensitive. Resistance comes with a catalytic cost: while P. brevicompactum IMPDH-B is >1000-fold more resistant to MPA than a typical eukaryotic IMPDH, its value of k(cat)/K(m) is 0.5% of “normal”. Curiously, IMPDH-B of Penicillium chrysogenum, which does not produce MPA, is also a very poor enzyme. The MPA binding site is completely conserved among sensitive and resistant IMPDHs. Mutational analysis shows that the C-terminal segment is a major structural determinant of resistance. These observations suggest that the duplication of the IMPDH gene in Pencillium subgenus Penicillium was permissive for MPA production and that MPA production created a selective pressure on IMPDH evolution. Perhaps MPA production rescued IMPDH-B from deleterious genetic drift

Recurrent venous thromboembolism and bleeding with extended anticoagulation: the VTE-PREDICT risk score

Aims Deciding to stop or continue anticoagulation for venous thromboembolism (VTE) after initial treatment is challenging, as individual risks of recurrence and bleeding are heterogeneous. The present study aimed to develop and externally validate models for predicting 5-year risks of recurrence and bleeding in patients with VTE without cancer who completed at least 3 months of initial treatment, which can be used to estimate individual absolute benefits and harms of extended anticoagulation. Methods and results Competing risk-adjusted models were derived to predict recurrent VTE and clinically relevant bleeding (non-major and major) using 14 readily available patient characteristics. The models were derived from combined individual patient data from the Bleeding Risk Study, Hokusai-VTE, PREFER-VTE, RE-MEDY, and RE-SONATE (n = 15,141, 220 recurrences, 189 bleeding events). External validity was assessed in the Danish VTE cohort, EINSTEIN-CHOICE, GARFIELD-VTE, MEGA, and Tromsø studies (n = 59 257, 2283 recurrences, 3335 bleeding events). Absolute treatment effects were estimated by combining the models with hazard ratios from trials and meta-analyses. External validation in different settings showed agreement between predicted and observed risks up to 5 years, with C-statistics ranging from 0.48–0.71 (recurrence) and 0.61–0.68 (bleeding). In the Danish VTE cohort, 5-year risks ranged from 4% to 19% for recurrent VTE and 1% –19% for bleeding. Conclusion The VTE-PREDICT risk score can be applied to estimate the effect of extended anticoagulant treatment for individual patients with VTE and to support shared decision-making

Hydrogenation properties of lithium and sodium hydride – closo-borate, [B10H10]2− and [B12H12]2−, composites

© 2018 the Owner Societies. The hydrogen absorption properties of metal closo-borate/metal hydride composites, M2B10H10-8MH and M2B12H12-10MH, M = Li or Na, are studied under high hydrogen pressures to understand the formation mechanism of metal borohydrides. The hydrogen storage properties of the composites have been investigated by in situ synchrotron radiation powder X-ray diffraction at p(H2) = 400 bar and by ex situ hydrogen absorption measurements at p(H2) = 526 to 998 bar. The in situ experiments reveal the formation of crystalline intermediates before metal borohydrides (MBH4) are formed. On the contrary, the M2B12H12-10MH (M = Li and Na) systems show no formation of the metal borohydride at T = 400 °C and p(H2) = 537 to 970 bar.11B MAS NMR of the M2B10H10-8MH composites reveal that the molar ratio of LiBH4or NaBH4and the remaining B species is 1:0.63 and 1:0.21, respectively. Solution and solid-state11B NMR spectra reveal new intermediates with a B:H ratio close to 1:1. Our results indicate that the M2B10H10(M = Li, Na) salts display a higher reactivity towards hydrogen in the presence of metal hydrides compared to the corresponding [B12H12]2-composites, which represents an important step towards understanding the factors that determine the stability and reversibility of high hydrogen capacity metal borohydrides for hydrogen storage

No significant effect on bone mineral density by high doses of vitamin D3 given to overweight subjects for one year

<p>Abstract</p> <p>Background</p> <p>In meta-analyses supplementation with vitamin D appears to reduce incidence of fractures, and in cross-sectional studies there is a positive association between serum 25-hydroxyvitamin D (25(OH)D) levels and bone mineral density (BMD). However, the effect of supplementation with high doses of vitamin D on BMD is more uncertain and could in theory have both positive and negative effects.</p> <p>Methods</p> <p>The study was a one year, double blind placebo-controlled intervention trial performed at the University Hospital of North Norway. 421 subjects, 21 - 70 years old, were included and 312 completed the study. The subjects were randomized to vitamin D₃40.000 IU per week (DD group), vitamin D₃20.000 IU per week (DP group), or placebo (PP group). All subjects were given 500 mg calcium daily. Serum 25(OH)D, osteoprotegrin (OPG), receptoractivator of nuclear factor-kappaB ligand (RANKL), and BMD at the lumbar spine and the hip were measured before and at the end of the study.</p> <p>Results</p> <p>At baseline the mean serum 25(OH)D levels were 58 nmol/L (all subjects) and increased to 141 and 100 nmol/L in the DD and DP groups, respectively. After one year, no significant differences were found between the three groups regarding change in BMD, serum OPG or RANKL.</p> <p>Conclusions</p> <p>Supplementation with high doses of vitamin D for one year does not appear to have a negative effect on BMD in healthy subjects. In order to disclose a positive effect, subjects with low BMD and/or low serum 25(OH)D levels need to be studied.</p> <p>Trial registration</p> <p>The trial was registered at ClinicalTrials.gov (NCT00243256).</p