[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.