Structural insights into the semiquinone form of human Cytochrome P450 reductase by DEER distance measurements between a native flavin and a spin labelled non-canonical amino acid

The flavoprotein Cytochrome P450 reductase (CPR) is the unique electron pathway from NADPH to Cytochrome P450 (CYPs). The conformational dynamics of human CPR in solution, which involves transitions from a "locked/closed" to an "unlocked/open" state, is crucial for electron transfer. To date, however, the factors guiding these changes remain unknown. By Site-Directed Spin Labelling coupled to Electron Paramagnetic Resonance spectroscopy, we have incorporated a non-canonical amino acid onto the flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) domains of soluble human CPR, and labelled it with a specific nitroxide spin probe. Taking advantage of the endogenous FMN cofactor, we successfully measured for the first time, the distance distribution by DEER between the semiquinone state FMNH• and the nitroxide. The DEER data revealed a salt concentration-dependent distance distribution, evidence of an "open" CPR conformation at high salt concentrations exceeding previous reports. We also conducted molecular dynamics simulations which unveiled a diverse ensemble of conformations for the "open" semiquinone state of the CPR at high salt concentration. This study unravels the conformational landscape of the one electron reduced state of CPR, which had never been studied before.

Single Mutations in Cytochrome P450 Oxidoreductase Can Alter the Specificity of Human Cytochrome P450 1A2-Mediated Caffeine Metabolism

A unique cytochrome P450 (CYP) oxidoreductase (CPR) sustains activities of human microsomal CYPs. Its function requires toggling between a closed conformation enabling electron transfers from NADPH to FAD and then FMN cofactors and open conformations forming complexes and transferring electrons to CYPs. We previously demonstrated that distinct features of the hinge region linking the FAD and FMN domain (FD) modulate conformer poses and their interactions with CYPs. Specific FD residues contribute in a CYP isoform-dependent manner to the recognition and electron transfer mechanisms that are additionally modulated by the structure of CYP-bound substrate. To obtain insights into the underlying mechanisms, we analyzed how hinge region and FD mutations influence CYP1A2-mediated caffeine metabolism. Activities, metabolite profiles, regiospecificity and coupling efficiencies were evaluated in regard to the structural features and molecular dynamics of complexes bearing alternate substrate poses at the CYP active site. Studies reveal that FD variants not only modulate CYP activities but surprisingly the regiospecificity of reactions. Computational approaches evidenced that the considered mutations are generally in close contact with residues at the FD-CYP interface, exhibiting induced fits during complexation and modified dynamics depending on caffeine presence and orientation. It was concluded that dynamic coupling between FD mutations, the complex interface and CYP active site exist consistently with the observed regiospecific alterations.

Confrontation of AlphaFold models with experimental structures enlightens conformational dynamics supporting CYP102A1 functions

Conformational dynamics plays a critical role for the function of multidomain electron transfer complexes. While crystallographic or NMR approaches allow detailed insight into structures, lower resolution methods like cryo-electron microscopy can provide more information on dynamics. In silico structure modelling using AlphaFold was recently successfully extended to the prediction of protein complexes but its capability to address large conformational changes involved in catalysis remained obscure. We used bacterial CYP102A1 monooxygenase homodimer as a test case to design a competitive modelling approach (CMA) for assessing alternate conformations of multi-domain complexes. Predictions were confronted with published crystallographic and cryo-EM data, evidencing consistencies but also permitting some reinterpretation of experimental data. Structural determinants stabilising the new type of domain connectivity evidenced in this bacterial self-sufficient monooxygenase were analysed by CMA and used for in silico retro-engineering applied to its eukaryotic bi-component counterparts.

Correlation of selected serum protein levels with the degree of disability and NEDA-3 status in multiple sclerosis phenotypes

OBJECTIVE

Multiple sclerosis (MS) is a multifactorial disease that begins in 80-85% of patients as a relapsing-remitting form (RRMS), and about 50% of patients gradually develop a secondary progressive form (SPMS). Approximately 10-20% of patients are affected primarily by the progressive form (PPMS) of this disease, which is characterised by a progressive course. This work focuses on the detection of potential protein biomarkers (CHI3L1, sNfL, CXCL13, MCP-1, MMP-2, and MMP-9) in the serum of patients with multiple sclerosis, divided according to phenotype.

PATIENTS AND METHODS

We detected serum (RRMS: n=40, SPMS: n=25, PPMS: n=15) concentrations of selected markers of demyelination and inflammation using ELISA and zymographic determination for accurate and reproducible recognition of individual forms of MS, as well as a comparison of their levels with a worsening of no evidence of disease activity (NEDA-3) status and patients' disability.

RESULTS

We detected that concentrations of sNfL in the blood of patients with PMS were higher than in those with RRMS (about 46%, p<0.001). The association with a worsening of NEDA-3 status was confirmed in the RRMS group by positive correlation of sNfL and the expanded disability status scale (EDSS) score (r=0.579, p<0.01). The levels of MCP-1 protein were not significantly different in patients with the RRMS to the progressive form of MS (r=0.58, p=0.02), while the levels of CHI3L1 in both the RRMS and PMS groups were significantly increased in groups with evidence of disease activity (RRMS about 76%, p<0.001 and PMS about 62%, p<0.001).

CONCLUSIONS

Earlier and non-invasive detection of serum biomarkers and their correlations with neurological disability can help to recognise the transition from RRMS to progressive forms of MS and complement the results of clinical and radiological follow-up of the patient and potentially help in monitoring the patient's response to the treatment.

Thermal Waves and Heat Transfer Efficiency Enhancement in Harmonically Modulated Turbulent Thermal Convection

We study turbulent Rayleigh-Bénard convection over four decades of Rayleigh numbers 4×10^{8}<Ra<2×10^{12}, while harmonically modulating the temperatures of the plates of our cylindrical cell. We probe the flow by temperature sensors placed in the cell interior and embedded in the highly conducting copper plates and detect thermal waves propagating at modulation frequency in the bulk of the convective flow. We confirm the recent numerical prediction [Yang et al., Phys. Rev. Lett. 125, 154502 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.154502] of the significant enhancement of the Nusselt number and report its dependence on the frequency and amplitude of the temperature modulation of plates.

Expression of selected inflammatory proteins and metalloproteinases in periodontitis

OBJECTIVE

Periodontitis is a chronic inflammatory disease caused by microbial dental plaque which leads to the destruction and loss of supporting tissues of the tooth. Microbial plaque alone, however, is not enough to cause the disease. The body's response plays an important role, in which an imbalance between the pro-inflammatory and anti-inflammatory effects of cytokines leads to an inflammatory reaction.

PATIENTS AND METHODS

We detected changes in mRNA expression and protein levels of MIP-1α, and metalloproteinases (MMP-2, MMP-9) contributing to cascades in the initiation and progression of inflammatory bone resorption and destruction of periodontal soft tissues in patients with aggressive (AP) or chronic (CP) forms of periodontitis in comparison with healthy individuals (control).

RESULTS

MIP-1α mRNA levels were highest in AP (280 ± 23% higher than the control) also in comparison with CP. The difference in protein level was less pronounced. MMP-2 mRNA expression values were similar (300 ± 12% higher in comparison with control), but protein levels were lower, also when compared to CP. Only in CP MMP-9 mRNA levels were significantly higher than the control (30 ± 8%), while protein levels were again higher in AP. Both AP and CP showed a positive correlation between the level of MIP-1a and MMP-2 (0.879, and 0.954 respectively). However, a strong positive correlation was only found between the levels of MMP-2 and MMP-9 in CP (0.812).

CONCLUSIONS

MIP-1α, MMP-2 and MMP-9 mRNA expression, along with the concentration of proteins in saliva in patients with periodontal disease, is higher than in healthy individuals and correlates with the severity of the disease.

Study of the K-S distance on skulls from different modern populations for sex and ancestry determination

In forensic science determination of the origin and sex of skeletal remains is an important task for identification purposes. In this study we investigated the krotaphion-sphenion distance (K‑S distance) in the pterion region of German, Euro-American, African-American and Rwandan skulls of modern individuals from the nineteenth to the twenty-first century to look for statistically significant differences in sex and ancestry. We found a statistically significant sex-specific difference in the K‑S distance, which was greater in male skulls than in female skulls for both sides of the skull. Our study also showed that there is a statistically significant difference in the K‑S distance between the four populations studied. Landmarks and morphometric parameters measured in our investigations, which were not used for the present examination were provided to the software program Fordisc for its reference data to enhance the range of its usability for identification of unknown skulls or partial skulls of European individuals.

Interaction Modes of Microsomal Cytochrome P450s with Its Reductase and the Role of Substrate Binding

The activity of microsomal cytochromes P450 (CYP) is strictly dependent on the supply of electrons provided by NADPH cytochrome P450 oxidoreductase (CPR). The variant nature of the isoform-specific proximal interface of microsomal CYPs implies that the interacting interface between the two proteins is degenerated. Recently, we demonstrated that specific CPR mutations in the FMN-domain (FD) may induce a gain in activity for a specific CYP isoform. In the current report, we confirm the CYP isoform dependence of CPR's degenerated binding by demonstrating that the effect of four of the formerly studied FD mutants are indeed exclusive of a specific CYP isoform, as verified by cytochrome c inhibition studies. Moreover, the nature of CYP's substrate seems to have a modulating role in the CPR:CYP interaction. In silico molecular dynamics simulations of the FD evidence that mutations induces very subtle structural alterations, influencing the characteristics of residues formerly implicated in the CPR:CYP interaction or in positioning of the FMN moiety. CPR seems therefore to be able to form effective interaction complexes with its structural diverse partners via a combination of specific structural features of the FD, which are functional in a CYP isoform dependent manner, and dependent on the substrate bound.

Thermal radiation in Rayleigh-Bénard convection experiments

An important question in turbulent Rayleigh-Bénard convection (RBC) is the effectiveness of convective heat transport, which is conveniently described via the scaling of the Nusselt number (Nu) with the Rayleigh (Ra) and Prandtl (Pr) numbers. In RBC experiments, the heat supplied to the bottom plate is also partly transferred by thermal radiation. This heat transport channel, acting in parallel with the convective and conductive heat transport channels, is usually considered insignificant and thus neglected. Here we present a detailed analysis of conventional far-field as well as strongly enhanced near-field radiative heat transport occurring in various RBC experiments. A careful inclusion of the radiative transport appreciably changes the Nu=Nu(Ra) scaling inferred in turbulent RBC experiments near ambient temperature utilizing gaseous nitrogen and sulfur hexafluoride as working fluids. On the other hand, neither the conventional far-field radiation nor the strongly enhanced near-field radiative heat transport appreciably affects the heat transport law deduced in cryogenic helium RBC experiments.

The Role of the FMN-Domain of Human Cytochrome P450 Oxidoreductase in Its Promiscuous Interactions With Structurally Diverse Redox Partners

NADPH cytochrome P450 oxidoreductase (CPR) is the obligatory electron supplier that sustains the activity of microsomal cytochrome P450 (CYP) enzymes. The variant nature of the isoform-specific proximal interface of microsomal CYPs indicates that CPR is capable of multiple degenerated interactions with CYPs for electron transfer, through different binding mechanisms, and which are still not well-understood. Recently, we showed that CPR dynamics allows formation of open conformations that can be sampled by its structurally diverse redox partners in a CYP-isoform dependent manner. To further investigate the role of the CPR FMN-domain in effective binding of CPR to its diverse acceptors and to clarify the underlying molecular mechanisms, five different CPR-FMN-domain random mutant libraries were created. These libraries were screened for mutants with increased activity when combined with specific CYP-isoforms. Seven CPR-FMN-domain mutants were identified, supporting a gain in activity for CYP1A2 (P117H, G144C, A229T), 2A6 (P117L/L125V, G175D, H183Y), or 3A4 (N151D). Effects were evaluated using extended enzyme kinetic analysis, cytochrome b₅ competition, ionic strength effect on CYP activity, and structural analysis. Mutated residues were located either in or adjacent to several acidic amino acid stretches – formerly indicated to be involved in CPR:CYP interactions – or close to two tyrosine residues suggested to be involved in FMN binding. Several of the identified positions co-localize with mutations found in naturally occurring CPR variants that were previously shown to cause CYP-isoform-dependent effects. The mutations do not seem to significantly alter the geometry of the FMN-domain but are likely to cause very subtle alterations leading to improved interaction with a specific CYP. Overall, these data suggest that CYPs interact with CPR using an isoform specific combination of several binding motifs of the FMN-domain.

Development of a Biosensor for Detection of Benzoic Acid Derivatives in Saccharomyces cerevisiae

4-hydroxybenzoic acid (pHBA) is an important industrial precursor of muconic acid and liquid crystal polymers whose production is based on the petrochemical industry. In order to decrease our dependency on fossil fuels and improve sustainability, microbial engineering is a particularly appealing approach for replacing traditional chemical techniques. The optimization of microbial strains, however, is still highly constrained by the screening stage. Biosensors have helped to alleviate this problem by decreasing the screening time as well as enabling higher throughput. In this paper, we constructed a synthetic biosensor, named sBAD, consisting of a fusion of the pHBA-binding domain of HbaR from R. palustris, the LexA DNA binding domain at the N-terminus and the transactivation domain B112 at the C-terminus. The response of sBAD was tested in the presence of different benzoic acid derivatives, with cell fluorescence output measured by flow cytometry. The biosensor was found to be activated by the external addition of pHBA in the culture medium, in addition to other carboxylic acids including p-aminobenzoic acid (pABA), salicylic acid, anthranilic acid, aspirin, and benzoic acid. Furthermore, we were able to show that this biosensor could detect the in vivo production of pHBA in a genetically modified yeast strain. A good linearity was observed between the biosensor fluorescence and pHBA concentration. Thus, this biosensor would be well-suited as a high throughput screening tool to produce, via metabolic engineering, benzoic acid derivatives.

Molecular recognition of aortic valve stenosis and regurgitation

OBJECTIVE

Aortic valve stenosis (AS) presents a disease during which there are changes of the aortic valve structure that modify the blood structure of patients. The aim of this study was to improve the effectiveness of differential diagnostics of aortic stenosis and aortic regurgitation using molecular techniques on both mRNA (RT-PCR) and protein (biochip protein).

PATIENTS AND METHODS

An experimental group (n = 58) consisting of patients with aortic valve stenosis (n = 26) and aortic regurgitation (AR, n = 32) was compared with a control group (n = 35). Both blood serum and valve tissue samples were used for the determination of gene expression specific genes related to inflammatory response (CRP, IL6, IL2R, IL6R, TNFR1, and 2) as well as genes and proteins involved in remodeling of the extracellular matrix (MMP9, TIMP, Emilin-1).

RESULTS

We found that hsCRP and IL6 plasma levels of patients with AS were higher than both controls and patients with AR (mean 5.6 ng/ml). The differences between AS and AR were detected only in mRNA levels of MMP9 and TIMP where increased levels characteristic for AS were found (about 74%, p < 0.01 and 87%, p < 0.001 higher than AR).

CONCLUSIONS

The achieved results could contribute to the improvement of early diagnosis of selected cardiovascular disease in the future and improve the quality of patient's life.

Elusive transition to the ultimate regime of turbulent Rayleigh-Bénard convection

By using cryogenic ^{4}He gas as the working fluid in a cylindrical cell 0.3 m in both height and diameter, we study the influence of non-Oberbeck-Boussinesq (NOB) effects on the heat transfer in turbulent Rayleigh-Bénard convection (RBC). We show that the NOB effects increase the heat transfer efficiency when the top plate temperature closely approaches the saturation vapor curve even far away from the critical point. Viewed in this light, our analysis points to the likelihood that the claim of having observed the transition to Kraichnan's ultimate regime, under nominally similar conditions in the experiments with SF_{6} [Phys. Rev. Lett. 108, 024502 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.024502], is probably an NOB effect and the important issue of the transition to the ultimate state of RBC remains open.

Probing the Role of the Hinge Segment of Cytochrome P450 Oxidoreductase in the Interaction with Cytochrome P450

NADPH-cytochrome P450 reductase (CPR) is the unique redox partner of microsomal cytochrome P450s (CYPs). CPR exists in a conformational equilibrium between open and closed conformations throughout its electron transfer (ET) function. Previously, we have shown that electrostatic and flexibility properties of the hinge segment of CPR are critical for ET. Three mutants of human CPR were studied (S243P, I245P and R246A) and combined with representative human drug-metabolizing CYPs (isoforms 1A2, 2A6 and 3A4). To probe the effect of these hinge mutations different experimental approaches were employed: CYP bioactivation capacity of pre-carcinogens, enzyme kinetic analysis, and effect of the ionic strength and cytochrome b₅ (CYB5) on CYP activity. The hinge mutations influenced the bioactivation of pre-carcinogens, which seemed CYP isoform and substrate dependent. The deviations of Michaelis-Menten kinetic parameters uncovered tend to confirm this discrepancy, which was confirmed by CYP and hinge mutant specific salt/activity profiles. CPR/CYB5 competition experiments indicated a less important role of affinity in CPR/CYP interaction. Overall, our data suggest that the highly flexible hinge of CPR is responsible for the existence of a conformational aggregate of different open CPR conformers enabling ET-interaction with structural varied redox partners.

Human cytochrome P450 expression in bacteria: Whole-cell high-throughput activity assay for CYP1A2, 2A6 and 3A4

Cytochrome P450s (CYPs) are key enzymes involved in drug and xenobiotic metabolism. A wide array of in vitro methodologies, including recombinant sources, are currently been used to assess CYP catalysis, to identify the metabolic profile of compounds, potential drug-drug interactions, protein-protein interactions in the CYP enzyme complex and the role of polymorphic enzymes. We report here on a bacterial whole-cells high-throughput method for the activity evaluation of human CYP1A2, 2A6, and 3A4, when sustained by NADPH cytochrome P450 oxidoreductase (CPR), in the absence or presence of cytochrome b₅ (CYB5). This new assay consists of a microplate real-time fluorometric method, with direct measurement of metabolite formation, in a suspension of Escherichia coli BTC-CYP bacteria, a human CYP competent tester strain when incubated with specific fluorogenic substrates. Overall, the maximum turnover (k_cat) velocities of the three human CYPs resulting from the whole-BTC cells assays were similar to those obtained when applying the corresponding standard reference membrane fractions assays. CYP activity screening with co-expression of CYB5 suggests an enhancing effect of CYB5 on the k_cat of specific isoforms, when using the whole-BTC cells assay. Our results demonstrate that this new approach can offer an efficient high-throughput method for screening of CYP1A2, 2A6 and 3A4 activity and can be potentially applicable for other human CYPs. This can be of particular use for timely and efficient screening of chemical libraries or mutant libraries of CYP enzyme complex proteins, without the necessity for labor intensive isolation of subcellular fractions.

Evaluation of molecular changes of distal organs after small bowel transplantation

The ischemia and reperfusion of a jejunal graft during transplantation triggers the stress of endoplasmic reticulum thus inducing the synthesis of pro-inflammatory cytokines. Spreading of these signals stimulate immunological reactions in distal tissues, i.e. lung, liver and spleen. The aim of this study was to detect the molecular changes in liver and spleen induced by transplanted jejunal graft with one or six hours of reperfusion (group Tx1 and Tx6). Analysis of gene expression changes of inflammatory mediators (TNF-alpha, IL-10) and specific chaperones (Gadd153, Grp78) derived from endoplasmic reticulum (ER) was done and compared to control group. The qRT-PCR method was used for amplification of the specific genes. The levels of corresponding proteins were detected by Western blot with immunodetection. Protein TNF-alpha was in liver tissue significantly overexpressed in the experimental group Tx1 by 48 % (p<0.001). In the group Tx6 we found decreased levels of the same protein to the level of controls. However, the protein concentrations of TNF-alpha in spleen showed increased levels in group Tx1 by 31 % (p<0.001) but even higher levels in the group Tx6 by 115 % (p<0.001) in comparing to controls. Our data demonstrated that the spleen is more sensitive to post-transplantation inflammation than liver, with consequent stress of ER potentially inducing apoptosis and failure of basic functions of lymphoid tissue.

A randomized adaptive phase II/III study of buparlisib, a pan-class I PI3K inhibitor, combined with paclitaxel for the treatment of HER2- advanced breast cancer (BELLE-4)

Background

Phosphatidylinositol 3-kinase (PI3K) pathway activation in preclinical models of breast cancer is associated with tumor growth and resistance to anticancer therapies, including paclitaxel. Effects of the pan-Class I PI3K inhibitor buparlisib (BKM120) appear synergistic with paclitaxel in preclinical and clinical models.

Patients and methods

BELLE-4 was a 1:1 randomized, double-blind, placebo-controlled, adaptive phase II/III study investigating the combination of buparlisib or placebo with paclitaxel in women with human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer with no prior chemotherapy for advanced disease. Patients were stratified by PI3K pathway activation and hormone receptor status. The primary endpoint was progression-free survival (PFS) in the full and PI3K pathway-activated populations. An adaptive interim analysis was planned following the phase II part of the study, after ≥125 PFS events had occurred in the full population, to decide whether the study would enter phase III (in the full or PI3K pathway-activated population) or be stopped for futility.

Results

As of August 2014, 416 patients were randomized to receive buparlisib (207) or placebo (209) with paclitaxel. At adaptive interim analysis, there was no improvement in PFS with buparlisib versus placebo in the full (median PFS 8.0 versus 9.2 months, hazard ratio [HR] 1.18), or PI3K pathway-activated population (median PFS 9.1 versus 9.2 months, HR 1.17). The study met protocol-specified criteria for futility in both populations, and phase III was not initiated. Median duration of study treatment exposure was 3.5 months in the buparlisib arm versus 4.6 months in the placebo arm. The most frequent adverse events with buparlisib plus paclitaxel (≥40% of patients) were diarrhea, alopecia, rash, nausea, and hyperglycemia.

Conclusions

Addition of buparlisib to paclitaxel did not improve PFS in the full or PI3K pathway-activated study population. Consequently, the trial was stopped for futility at the end of phase II.

[The Importance of MITF Signaling Pathway in the Regulation of Proliferation and Invasiveness of Malignant Melanoma]

BACKGROUND

Malignant melanoma is one of the most aggressive types of cancers. Melanoma is derived from pigment-producing cells, melanocytes, which are characterized by a specific survival mechanism. Microphthalmia-associated transcription factor (MITF-M) plays a role in the metabolism of melanoma and is involved in the regulation of the expression of multiple genes mediating processes such as melanogenesis, proliferation, differentiation, and melanocyte survival. The expression of this transcription factor in melanocytes is activated by several signaling pathways, and reduced expression or function of MITF-M can cause the dysregulation of anti-apoptotic mechanisms. MITF-M is also involved in matrix metalloproteinase 14 (MMP14) activity, which is responsible for shape changes in melanocytes and increases in their motility and invasiveness. Very low levels of expression of MITF-M are found in human melanocytes with an invasive phenotype, indicating that this transcription factor acts as a suppressor of the metastatic process. Cancer cells with low expression of cytosolic/nuclear β-catenin have a small amount of MITF-M 14 that is insufficient to inhibit MMP transcription. The enzyme catalyzes the degradation of laminin and fibronectin, thereby changing the shape of melanocytes, which leads to their increased mobility and invasiveness.

AIMS

This review describes the regulatory pathway of MITF-M activation, its involvement in the proliferation of transformed melanocytes, and its role in increasing the invasiveness of malignant melanoma. A detailed understanding of the MITF-M signaling pathway is highly topical and could help to develop new diagnostic and therapeutic applications for patients with malignant melanoma.Key words: neoplastic cell transformation - melanoma - MITF transcription factorThis work was supported by grant projects VEGA 1/0115/14 and VEGA 1/0873/16.The authors declare they have no potential confl icts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 4. 12. 2015Accepted: 14. 6. 2016.

Phase II study of buparlisib (BKM120) and trastuzumab in patients with HER2+ locally advanced or metastatic breast cancer resistant to trastuzumab-based therapy

PURPOSE

A Phase Ib study in patients with trastuzumab-resistant, human epidermal growth factor receptor-2- (HER2)-positive advanced breast cancer defined the recommended Phase II dose of buparlisib as 100 mg/day in combination with 2 mg/kg weekly trastuzumab, and reported preliminary signs of clinical activity. Here we present results from the Phase II portion.

METHODS

Patients with trastuzumab-resistant, HER2-positive advanced breast cancer received buparlisib plus trastuzumab. Study endpoints included safety/tolerability and antitumour activity. The study was extended to include a Phase Ib dose-escalation phase, in which patients with progressive brain metastases also received capecitabine.

RESULTS

In the Phase II portion, of 50 patients treated with buparlisib and trastuzumab, the most common (≥ 30%) all-grade adverse events (AEs) were diarrhoea (54%), nausea (48%), decreased appetite, increased alanine aminotransferase (36% each), increased aspartate aminotransferase (34%), fatigue, rash (32% each), cough and hyperglycemia (30% each). One (2%) patient achieved complete response and four (8%) patients had confirmed partial responses [PR; including two patients with phosphatidylinositol 3-kinase (PI3 K) pathway-activated tumours]. Overall response rate (ORR) was 10%: the primary endpoint (ORR ≥ 25%) was therefore not met. In the Phase Ib portion, all patients with measurable brain lesions at baseline showed tumour shrinkage to some degree; due to low enrollment, maximum tolerated dose of buparlisib in combination with trastuzumab and capecitabine was not determined.

CONCLUSION

Buparlisib plus trastuzumab, as a chemotherapy-free regimen, demonstrated an acceptable safety profile but limited efficacy in patients with heavily pretreated, trastuzumab-resistant HER2-positive breast cancer, and in patients with progressive brain metastases also receiving capecitabine.

RADON CHAMBER IN THE CENTRAL MINING INSTITUTE-THE CALIBRATION FACILITY FOR RADON AND RADON PROGENY MONITORS

The article presents the advantages of the radon chamber with volume of 17 m3, that belongs to Silesian Centre for Environmental Radioactivity and its applicability for calibration of equipment designed to measure the radon concentration and its short-lived decay products. The chamber can be operated under controlled conditions in the range from -20 to 60°C and relative humidity from 20 to 90%. There is also discussed the influence of aerosol concentration and their size distribution on the calibration results. When calibrating the measuring devices in an atmosphere with a large contribution of ultrafine particles that are defined as particles with diameter <0.1 μm, their sensitivity may decrease by tens of percent.

MEASUREMENTS OF AIRBORNE CONCENTRATIONS OF RADON AND THORON DECAY PRODUCTS

Liquid scintillation counting (LSC) is a measuring technique, broadly applied in environmental monitoring of radionuclides. One of the possible applications of LSC is the measurement of radon and thoron decay products. But this method is suitable only for grab sampling. For long-term measurements a different technique can be applied-monitors of potential alpha energy concentration (PAEC) with thermoluminescent detectors (TLD). In these devices, called Alfa-2000 sampling probe, TL detectors (CaSO4:Dy) are applied for alpha particles counting. Three independent heads are placed over the membrane filter in a dust sampler's microcyclone. Such solution enables simultaneous measurements of PAEC and dust content. Moreover, the information which is stored in TLD chips is the energy of alpha particles, not the number of counted particles. Therefore, the readout of TL detector shows directly potential alpha energy, with no dependence on equilibrium factor, etc. This technique, which had been used only for radon decay products measurements, was modified by author to allow simultaneous measurements of radon and thoron PAEC. The LSC method can be used for calibration of portable radon decay products monitors. The LSC method has the advantage to be an absolute one, the TLD method to measure directly the (dose relevant) deposited energy.

The Hinge Segment of Human NADPH-Cytochrome P450 Reductase in Conformational Switching: The Critical Role of Ionic Strength

NADPH-cytochrome P450 reductase (CPR) is a redox partner of microsomal cytochromes P450 and is a prototype of the diflavin reductase family. CPR contains 3 distinct functional domains: a FMN-binding domain (acceptor reduction), a linker (hinge), and a connecting/FAD domain (NADPH oxidation). It has been demonstrated that the mechanism of CPR exhibits an important step in which it switches from a compact, closed conformation (locked state) to an ensemble of open conformations (unlocked state), the latter enabling electron transfer to redox partners. The conformational equilibrium between the locked and unlocked states has been shown to be highly dependent on ionic strength, reinforcing the hypothesis of the presence of critical salt interactions at the interface between the FMN and connecting FAD domains. Here we show that specific residues of the hinge segment are important in the control of the conformational equilibrium of CPR. We constructed six single mutants and two double mutants of the human CPR, targeting residues G240, S243, I245 and R246 of the hinge segment, with the aim of modifying the flexibility or the potential ionic interactions of the hinge segment. We measured the reduction of cytochrome c at various salt concentrations of these 8 mutants, either in the soluble or membrane-bound form of human CPR. All mutants were found capable of reducing cytochrome c yet with different efficiency and their maximal rates of cytochrome c reduction were shifted to lower salt concentration. In particular, residue R246 seems to play a key role in a salt bridge network present at the interface of the hinge and the connecting domain. Interestingly, the effects of mutations, although similar, demonstrated specific differences when present in the soluble or membrane-bound context. Our results demonstrate that the electrostatic and flexibility properties of the hinge segment are critical for electron transfer from CPR to its redox partners.

[Idiopathic cranial nerve failure]

Cranial nerve lesions require a thorough diagnostic work-up and known etiologies have to be excluded before the term idiopathic can be considered. The focus of the present review is on idiopathic peripheral facial nerve paralysis (Bell's palsy) for which this terminology has been established. For all other cranial nerve lesions the typical clinical signs, established etiologies and possible diagnostic pitfalls are discussed.

Analysis of transcriptional activities of angiogenic biomarkers during intrauterine complications leading to preterm birth

OBJECTIVE

Pre-eclampsia, growth retardation and preterm delivery are the most common reasons leading to increased maternal and perinatal mortality. The increased expression of hypoxia induced factors, such as HIF-1, triggers the overexpression of anti-angiogenic genes. The aim of this study was to determine the transcriptional activity of individual pro- and anti-angiogenic markers (VEGF, HIF-1, sEng, Flt-1, PlGF-1) in maternal blood samples from patients with spontaneous preterm labor, preterm labor in combination with pre-eclampsia and fetal growth restriction in comparison with physiologically terminated pregnancies.

PATIENTS AND METHODS

The transcriptional activity of specific genes was detected from the blood of patients using the chromatin immunoprecipitation capture method coupled with quantitative real-time PCR.

RESULTS

The maximum differences in mRNA levels of PlGF-1 and VEGF-A were detected in two groups: the group of normal-term birth with complications and the group of preterm labor with complications (both significantly lower than the control, p < 0.001). In contrast, a marked increase of mRNA levels was found in the same groups of patients for the HIF-1, endoglin and Flt-1 genes (p < 0.001).

CONCLUSIONS

According to our results, we can conclude that increased oxidative stress, increasing the expression levels of anti-angiogenic genes and reduction of the transcriptional activity of pro-angiogenic genes can provide additional information during diagnostics of pathological complications of labor.

[Wearable Technique for the Assessment of Parkinson Symptoms: What's the Future?]

Parkinson's disease (PD) is a multisystem disorder with a plethora of symptoms affecting the quality of life of patients in the home environment. Due to the rapid development of wearable technique in the health and fitness sector, an increasing number of such wearable devices are available to complement diagnostic strategies of PD symptoms not only in the clinical but also in the home environment. This development has clear advantages over clinical evaluation, as the latter is relatively subjective, time-consuming and costly, and provides only a snapshot of the condition. First results about the use of such technology for the assessment of PD symptoms (including bradykinesia, dyskinesia, tremor, daily activity and sleep behavior) in the home environment are promising. They suggest that these techniques can provide complementary information about the symptoms of PD patients, and have the potential to be included in future diagnostic workup concepts of routine care in PD. The use of such technique provides also the opportunity to more actively include patients into medical decision-making processes.

Functional characterization of zebrafish cytochrome P450 1 family proteins expressed in yeast

BACKGROUND

Zebrafish express five cytochrome P450 1 genes: CYP1A, CYP1B1, CYP1C1, CYP1C2, inducible by aryl hydrocarbon receptor agonists, and CYP1D1, a constitutively expressed CYP1A-like gene. We examined substrate selectivity of CYP1s expressed in yeast.

METHODS

CYP1s were expressed in W(R) yeast, engineered to over-express P450 reductase, via pYES/DEST52 and via pYeDP60. Microsomal fractions from transformed yeast were examined for activity with fluorogenic substrates, benzo[a]pyrene and testosterone. Modeling and docking approaches were used to further evaluate sites of oxidation on benzo[a]pyrene and testosterone.

RESULTS

CYP1s expressed in yeast dealkylated ethoxy-, methoxy-, pentoxy- and benzoxy-resorufin (EROD, MROD, PROD, BROD). CYP1A and CYP1C2 had the highest rates of EROD activity, while PROD and BROD activities were low for all five CYP1s. The relative rates of resorufin dealkylation by CYP1C1, CYP1C2 and CYP1D1 expressed via pYeDP60 were highly similar to relative rates obtained with pYES/DEST52-expressed enzymes. CYP1C1 and CYP1C2 dealkylated substituted coumarins and ethoxy-fluorescein-ethylester, while CYP1D1 did not. The CYP1Cs and CYP1D1 co-expressed with epoxide hydrolase oxidized BaP with different rates and product profiles, and all three produced BaP-7,8,9,10-tetrol. The CYP1Cs but not CYP1D1 metabolized testosterone to 6β-OH-testosterone. However, CYP1D1 formed an unidentified testosterone metabolite better than the CYP1Cs. Testosterone and BaP docked to CYP homology models with poses consistent with differing product profiles.

CONCLUSIONS

Yeast-expressed zebrafish CYP1s will be useful in determining further functionality with endogenous and xenobiotic compounds.

GENERAL SIGNIFICANCE

Determining the roles of zebrafish CYP1s in physiology and toxicology depends on knowing the substrate selectivity of these enzymes.

Essential Hypertension: Cardiovascular Response to Breath Hold Combined with Exercise

Essential hypertension (EH) is a widespread disease and might be prevalent in apnea divers and master athletes. Little is known about the influence of EH and the antihypertensive drugs (AHD) on cardiovascular reactions to combined breath hold (BH) and exercise. In this pilot study, healthy divers (HCON) were compared with treated hypertensive divers with regard to heart rate (HR) and mean blood-pressure (MAP) responses to BH, exercise and the combination of both. Ten subjects with EH and ten healthy divers were tested. 3 different 20 s stimuli were applied: BH combined with 30 W or 150 W and 150 W without BH. The time-charts during the stress intervals and during recovery were compared. Subjects treated with an angiotensin-converting enzyme (ACE) inhibitor showed higher changes for MAP values if breath hold was performed. HR responses were obviously changed if a β-blocker was part of the medication. One subject showed extreme MAP responses to all stimuli and conspicuous HR if BH was involved. The modulation of HR-/MAP-response in EH subjects depends on the mechanisms of antihypertensive agents. The combination of an ACE inhibitor and a β-blocker may give the best protection. It is recommended to include short apnea tests in the fitness-to-dive examination to individually predict potential endangerment.

Altered substrate specificity of the Pterygoplichthys sp. (Loricariidae) CYP1A enzyme

Ethoxyresorufin is a classical substrate for vertebrate CYP1A enzymes. In Pterygoplichthys sp. (Loricariidae) this enzyme possesses 48 amino acids substitutions compared to CYP1A sequences from other vertebrate species. These substitutions or a certain subset substitution are responsible for the non-detection of the EROD reaction in this species liver microsomes. In the present study, we investigated the catalytic activity of Pterygoplichthys sp. CYP1A toward 15 potential substrates in order to understand the substrate preferences of this modified CYP1A. The fish gene was expressed in yeast and the accumulation of the protein was confirmed by both the characteristic P450-CO absorbance spectra and by detection with monoclonal antibodies. Catalytic activities were assayed with yeast microsomes and four resorufin ethers, six coumarin derivates, three flavones, resveratrol and ethoxyfluoresceinethylester. Results demonstrated that the initial velocity pattern of this enzyme for the resorufin derivatives is different from the one described for most vertebrate CYP1As. The initial velocity for the activity with the coumarin derivatives is several orders of magnitude higher than with the resorufins, i.e. the turnover number (kcat) for ECOD is 400× higher than for EROD. Nonetheless, the specificity constant (kcat/km) for EROD is only slightly higher than for ECOD. EFEE is degraded at a rate comparable to the resorufins. Pterygoplichthys sp. CYP1A also degrades 7-methoxyflavone and β-naphthoflavone but not resveratrol and chrysin. These results indicate a divergent substrate preference for Pterygoplichthys sp. CYP1A, which may be involved in the adaptation of Loricariidae fish to their particular environment and feeding habits.

[Occupational tuberculosis in Slovakia and in the Czech Republic]

STUDY OBJECTIVE

To conduct a retrospective 15-year study to monitor trends in the number of employees at risk for occupational tuberculosis (TB) (levels III and IV) in the Slovak Republic, and in particular in the sector of economic activities Q (health care and social assistance). Furthermore, to analyze reported cases of occupational TB and to compare the incidence and sex-specific and age-specific prevalence with the data reported in the Czech Republic.

MATERIAL AND METHODS

Data on the number of employees at risk of exposure to occupational TB were derived from the Automated Risk Classification System of the Slovak Republic. Data on cases of occupational TB were taken from health statistics (Institute of Health Information and Statistics/National Health Information Center in the Slovak Republic and the National Institute of Public Health in the Czech Republic). A retrospective analysis was conducted (for 1998-2012) of reported cases of occupational TB, selected from Article 24 of the List of occupational diseases (infectious and parasitic diseases except tropical infectious and parasitic diseases and diseases transmissible from animals to humans). The selection criterion was a TB diagnosis according to ICD-10. In the Czech Republic, the data were derived from Article 5.1.02 (tuberculosis), Chapter V. of the List of Occupational Diseases. The data obtained were analyzed by methods of descriptive statistics.

RESULTS

The numbers of employees with a level III risk of exposure to occupational TB in the Slovak Republic declined by 30% over the 15 years of study and by 40% in category Q. In 2012, 2027 employees were classified in category III and 1442 of them belonged to group Q. Females accounted for 81-84% of employees at risk of exposure to occupational TB. Eighty-six and 181 cases of occupational TB were reported in the Slovak Republic and in the Czech Republic, respectively, in 1998-2012, with the incidence showing a downward trend in both countries. TB of the respiratory tract was reported most often (83.7% of the total of reported cases of occupational TB). As expected, more cases occurred in females than in males (1.9 times as many cases in females as in males in the Slovak Republic and three times as many cases in females as in males in the Czech Republic). The incidence of occupational TB was the highest in sector Q, with the highest absolute numbers reported in nurses. In 2012, the incidence rates of occupational TB were 0.22 cases per 100,000 sick benefit policy holders in the Slovak Republic and 0.13 cases per 100,000 sick benefit policy holders in the Czech Republic.

CONCLUSION

The incidence of occupational TB has a downward trend in both countries, similarly to TB incidence in the general population. A negative aspect in both countries is the incidence of occupational TB at the middle productive age, in contrast to the population occupationally non-exposed to TB. Slovakia is surrounded by higher prevalence countries, with the exception of the Czech Republic. It cannot be ruled out that, in addition to the known factors influencing the prevalence of TB, including occupational TB, migration from eastern countries, including job search migration, can also play a role in increase in TB cases. It is vital to continue epidemiological surveillance and to reduce the risk of TB as much as possible also in healthcare settings by adhering to barrier nursing practices. Cases of active TB need early and adequately long, controlled treatment in order to reduce, among others, the incidence of multi-drug resistant TB.

[Effect of vitamin d receptor polymorphisms on the development and progression of malignant melanoma]

BACKGROUND

Malignant melanoma is one of the most aggressive cutaneous tumors in men and women. The risk of developing a malignant melanoma depends on several external factors along with deregulation of mutual interaction of genotype and phenotype. Nowadays, growing attention is focused on the study of the interactions of the active form of vitamin D3 with its receptor and inhibitory effect of vitamin D3 receptor polymorphisms on multiple signaling pathways involved in proliferative and metastatic processes.

OBJECTIVES

This review article addresses the relationship between factors involved in the development of malignant melanoma through Hedgehog signaling pathway (HH). It summarizes current knowledge of malignant melanoma in regard to the role of the active form of vitamin D3 binding to vitamin D3 receptor (VDR), as well as it describes the influence of polymorphisms of VDR on the inhibition of HH. Understanding of these mechanisms and critical assessment of available data is beneficial to both primary and secondary prevention of malignant melanoma particularly by means of chemo -preventive substances.

Abstract OT2-6-08: Phase II, randomized, parallel-cohort study of neoadjuvant buparlisib (BKM120) in combination with trastuzumab and paclitaxel in women with HER2-positive, PIK3CA mutant and PIK3CA wild-type primary breast cancer – NeoPHOEBE

Background: The PI3K/Akt/mTOR pathway is frequently activated in breast cancer (BC) and is important for the oncogenic function of HER2. Buparlisib is an oral pan-PI3K inhibitor that targets all 4 isoforms of class I PI3K (α, β, γ, Δ). Preliminary clinical activity was observed with buparlisib in patients (pts) with advanced BC as a single agent, and in combination with paclitaxel (Dirix et al. ESMO 2012) or trastuzumab (Pistilli et al. ESMO 2012).

Study design: NeoPHOEBE (NCT01816594) is a Phase II, randomized, double-blind, parallel-cohort study of neoadjuvant buparlisib or matched placebo plus trastuzumab and weekly paclitaxel. Upfront stratification of pts into 2 independent cohorts according to PIK3CA mutation status will determine whether pts with PIK3CA-mutant tumors may benefit more from this treatment combination. Adult women with newly diagnosed, HER2-positive, primary non-inflammatory BC who have not previously received systemic therapy for invasive disease are eligible. Other eligibility criteria: tumor size &gt;2 cm; unilateral disease; available tumor tissue for central review of estrogen receptor (ER) and HER2 status, and PIK3CA genotype; known PIK3CA mutation status; and ECOG PS ≤1. Pts in each cohort (PIK3CA mutant or wild-type [wt]) are randomized (1:1) to receive continuous daily buparlisib (100 mg) or placebo and weekly trastuzumab (4 mg/kg loading dose then 2 mg/kg) for 6 weeks, followed by continuous daily buparlisib (80 mg) or placebo with weekly trastuzumab (2 mg/kg) and weekly paclitaxel (80 mg/m2) for 12 weeks. Study treatment is followed by surgery within 4 weeks of last paclitaxel dose. Stratification at randomization is based on PIK3CA (mutant vs wt) and ER (positive vs negative) status.

Endpoints: All endpoints will be measured in both PIK3CA-mutant and wt cohorts. The primary endpoint is rate of pathologic complete response (pCR; ypT0) at time of surgery. The key secondary endpoint is objective response rate (ORR) at the end of week 6. Other secondary endpoints include pCR by other definitions, ORR prior to surgery, pCR and objective response by ER status, percent of pts with node-negative disease at surgery, rate of breast conserving surgery, and safety. Exploratory objectives include change in standardized uptake value (SUV) at Day 15 by FDG-PET; and ORR and pCR by PTEN expression, Ki67 level, apoptosis rates, percentage of tumor infiltrating lymphocytes (TIL), and by phenotype of 50% TIL at baseline.

Statistical methods: The sample size is based on a minimax 2-stage randomized Phase II design with a prospective control. This design allows for early stopping if the desired efficacy is not observed after stage 1. Both cohorts are powered (80%) to detect a clinically meaningful increase in pCR of 18% at a one-sided significance level (α = 0.15).

Target accrual: Planned enrollment for NeoPHOEBE is up to 220 pts at 65 sites in 12 countries across South America, Europe, and Asia-Pacific.

Contact: For further study information, contact BIG@bordet.be.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT2-6-08.