Changes of c-myc expression in b16 melanoma cells induced by 8-chloroadenosine-3′, 5′-monophosphate and tiazofurin

The aim of this study was to investigate the in vitro effects of 8- chloroadenosine 3′, 5′-monophosphate (8-Cl-cAMP) and tiazofurin (TR) on the expression of c-myc gene in B16/F10 and B16/C3 mouse melanoma cells. Exponentially growing cells were treated with 8-Cl-cAMP or TR (5µmol - 25µmol) for 6h and 24h. The level of c-myc expression, estimated by RT-PCR, did not significantly change in B16/F10 cells after treatment with 8-Cl-cAMP or TR. Similar results were obtained in B16/C3 cells after treatment with 8-Cl-cAMP. The level of c-myc expression has shown a significant increase in B16/C3 cells after treatment with TR. Further studies of these agents will lead to better understanding of molecular mechanisms of their action.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Radiosensitivity of human ovarian carcinoma and melanoma cells to gamma-rays and protons

Introduction: Proton radiation offers physical advantages over conventional radiation. Radiosensitivity of human 59M ovarian cancer and HTB140 melanoma cells was investigated after exposure to gamma-rays and protons. Material and methods: Irradiations were performed in the middle of a 62 MeV therapeutic proton spread out Bragg peak with doses ranging from 2 to 16 Gy. The mean energy of protons was 34.88+/-2.15 MeV, corresponding to the linear energy transfer of 4.7+/-0.2 keV/mu m. Irradiations with gamma-rays were performed using the same doses. Viability, proliferation and survival were assessed 7 days after both types of irradiation while analyses of cell cycle and apoptosis were performed 48 h after irradiation. Results: Results showed that gamma-rays and protons reduced the number of viable cells for both cell lines, with stronger inactivation achieved after irradiation with protons. Surviving fractions for 59M were 0.91+/-0.01 for gamma-rays and 0.81+/-0.01 for protons, while those for HTB140 cells were 0.93+/-0.01 for gamma-rays and 0.86+/-0.01 for protons. Relative biological effectiveness of protons, being 2.47+/-0.22 for 59M and 2.08+/-0.36 for HTB140, indicated that protons provoked better cell elimination than gamma-rays. After proton irradiation proliferation capacity of the two cell lines was slightly higher as compared to gamma-rays. Proliferation was higher for 59M than for HTB140 cells after both types of irradiation. Induction of apoptosis and G2 arrest detected after proton irradiation were more prominent in 59M cells. Conclusions: The obtained results suggest that protons exert better antitumour effects on ovarian carcinoma and melanoma cells than gamma-rays. The dissimilar response of these cells to radiation is related to their different features

European Atlas of Natural Radiation

Natural ionizing radiation is considered as the largest contributor to the collective effective dose received by the world population. The human population is continuously exposed to ionizing radiation from several natural sources that can be classified into two broad categories: high-energy cosmic rays incident on the Earth’s atmosphere and releasing secondary radiation (cosmic contribution); and radioactive nuclides generated during the formation of the Earth and still present in the Earth’s crust (terrestrial contribution). Terrestrial radioactivity is mostly produced by the uranium and thorium radioactive families together with potassium. In most circumstances, radon, a noble gas produced in the radioactive decay of uranium, is the most important contributor to the total dose. This Atlas aims to present the current state of knowledge of natural radioactivity, by giving general background information, and describing its various sources. This reference material is complemented by a collection of maps of Europe displaying the levels of natural radioactivity caused by different sources. It is a compilation of contributions and reviews received from more than 80 experts in their field: they come from universities, research centres, national and European authorities and international organizations. This Atlas provides reference material and makes harmonized datasets available to the scientific community and national competent authorities. In parallel, this Atlas may serve as a tool for the public to: • familiarize itself with natural radioactivity; • be informed about the levels of natural radioactivity caused by different sources; • have a more balanced view of the annual dose received by the world population, to which natural radioactivity is the largest contributor; • and make direct comparisons between doses from natural sources of ionizing radiation and those from man-made (artificial) ones, hence to better understand the latter.JRC.G.10-Knowledge for Nuclear Security and Safet

Osmotically Activated Anion Current of Phycomyces Blakesleeanus—Filamentous Fungi Counterpart to Vertebrate Volume Regulated Anion Current

Studies of ion currents in filamentous fungi are a prerequisite for forming a complete understanding of their physiology. Cytoplasmic droplets (CDs), obtained from sporangiophores of Phycomyces blakesleeanus, are a model system that enables the characterization of ion currents in the native membrane, including the currents mediated by the channels not yet molecularly identified. Osmotically activated anionic current with outward rectification (ORIC) is a dominant current in the membrane of cytoplasmic droplets under the conditions of hypoosmotic stimulation. We have previously reported remarkable functional similarities of ORIC with the vertebrate volume regulated anionic current (VRAC), such as dose-dependent activation by osmotic difference, ion selectivity sequence, and time and voltage dependent profile of the current. Using the patch clamp method on the CD membrane, we further resolve VRAC-like ORIC characteristics in this paper. We examine the inhibition by extracellular ATP and carbenoxolone, the permeation of glutamate in presence of chloride, selectivity for nitrates, and activation by GTP, and we show its single channel behavior in excised membrane. We propose that ORIC is a functional counterpart of vertebrate VRAC in filamentous fungi, possibly with a similar essential role in anion efflux during cell volume regulation

ATP modulation of osmotically activated anionic current in the membrane of Phycomyces blakesleeanus sporangiophore

Abstract Ion channels are vital components of filamentous fungi signaling in communication with their environment. We exploited the ability of the apical region of growing sporangiophores of Phycomyces blakesleeanus to form membrane-enveloped cytoplasmic droplets (CDs), to examine ion currents in the filamentous fungi native plasma membrane. In hypoosmotic conditions, the dominant current in the CDs is ORIC, an osmotically activated, anionic, outwardly rectified, fast inactivating instantaneous current that we have previously characterized. Here, we examined the effect of ATP on ORIC. We show that CDs contain active mitochondria, and that respiration inhibition by azide accelerates ORIC inactivation. ATP, added intracellularly, reduced ORIC run-down and shifted the voltage dependence of inactivation toward depolarized potentials, in a manner that did not require hydrolysis. Notably, ATP led to slowing down of ORIC inactivation, as evidenced by an increased time constant of inactivation, τin, and slower decline of τin during prolonged recordings. Flavonoids (genistein and quercetin) had the effect on ORIC opposite to ATP, acting as current inhibitors, possibly by disrupting the stabilizing effect of ATP on ORIC. The integration of osmotic sensing with ATP dependence of the anionic current, typical of vertebrate cells, is described here for the first time in filamentous fungi

Inhibition of B16 mouse melanoma cell growth and induction of apoptotic cell death with 8-chloroadenosine-3 5,-monophosphate and tiazofurin

Novel antineoplastic agents, 8-chloroadenosine 3,5-monophosphate (8-Cl-cAMP) and tiazofurin (TR), have been shown to be effective against different malignant cells. Through specific mechanisms of action they modulate the cellular signal transduction pathway, thereby causing growth inhibition, cell differentiation, and apoptosis. The aim of this work was the in vitro study of either 8-Cl-cAMP or TR effects on B16/F10 and B16/C3 mouse melanoma cell growth and cell death. Significant cell growth inhibition was obtained after the application of 8-Cl-cAMP or TR. The presence and number of apoptotic cells was evaluated using agarose gel electrophoresis and flow cytometry. The number of apoptotic nuclei, after treatment with antineoplastic agents, did not significantly change in B16/F10 cells, although it did show a significant increase in B16/C3 cells. The expression of c-myc did not significantly change in B16/F10 cells after treatment with 8-Cl-cAMP or TR. The same results were obtained in B16/C3 cells after treatment with 8-Cl-cAMP. The level of c-myc expression showed a significant increase in B16/C3 cells after treatment with TR. Concerning the effects that the analyzed agents exhibited on melanoma cells and other cancer cells, further preclinical studies of these drugs will potentially lead to better understanding of the molecular mechanisms of their action and finally more efficient therapeutic approaches to malignant diseases.Conference on Signal Transduction Pathways, Chromatin Structures and Gene Expression Mechanisms as Therapeutic Targets (Science Week 2004), Jan 25-31, 2004, Luxembourg, Luxembour

Synthesis, structure and solvatochromic properties of 3-cyano--4,6-diphenyl-5-(3- and 4-substituted phenylazo)-2-pyridones

Abstract: A series of some new pyridone arylazo dyes was synthesized from the corresponding diazonium salts and 3-cyano-4,6-diphenyl-2-pyridone using the classical reaction for the synthesis of the azo compounds. The structures of these dyes were confirmed by UV–Vis, FT-IR and 1 H-NMR spectroscopic techniques. The solvatochromism of the dyes was evaluated with respect to visible absorption properties in various solvents. The effects of solvent dipolarity/polarizability and solvent/solute hydrogen bonding interactions were analyzed by means of the linear solvation energy relationship concept proposed by Kamlet and Taft. The 2-pyridone/2-hydroxypiridine tautomeric equilibration was found to depend on the substituents as well as on the solvents

Downregulation of c-fos and c-myc expression and apoptosis induction by tiazofurin and 8-Cl-cAMP in human melanoma cells

Tiazofurin and 8-Cl-cAMP are novel antineoplastic agents that have been shown to be effective against various cancer cells in vitro and in vivo. Through specific mechanisms of action they modulate the cellular signal transduction pathway, thereby causing growth inhibition, cell differentiation, apoptosis and downregulation of c-ras and c-myc gene expression. We examined the effects of 8-Cl-cAMP and tiazofurin, either separately or together, on apoptosis induction and c-fos and c-myc expression in melanoma cells. 8-Cl-cAMP and tiazofurin inhibited the growth of melanoma cells in a dose-responsive manner. Whether used separately or together, each agent induced apoptotic cell death. Apoptosis was accompanied by a marked inhibition of c-fos and c-mye gene expression. RT-PCR analysis showed that 8-Cl-cAMP, together with tiazofurin, promoted 61% and 75% decreases of c-myc and c-fos expression in melanoma cells respectively. These results clearly indicate that the combination of 8-Cl-cAMP and tiazofurin could provide a promising therapeutic approach for melanoma treatment

Downregulation of c-fos and c-myc expression and apoptosis induction by tiazofurin and 8-Cl-cAMP in human melanoma cells

Tiazofurin and 8-Cl-cAMP are novel antineoplastic agents that have been shown to be effective against various cancer cells in vitro and in vivo. Through specific mechanisms of action they modulate the cellular signal transduction pathway, thereby causing growth inhibition, cell differentiation, apoptosis and downregulation of c-ras and c-myc gene expression. We examined the effects of 8-Cl-cAMP and tiazofurin, either separately or together, on apoptosis induction and c-fos and c-myc expression in melanoma cells. 8-Cl-cAMP and tiazofurin inhibited the growth of melanoma cells in a dose-responsive manner. Whether used separately or together, each agent induced apoptotic cell death. Apoptosis was accompanied by a marked inhibition of c-fos and c-mye gene expression. RT-PCR analysis showed that 8-Cl-cAMP, together with tiazofurin, promoted 61% and 75% decreases of c-myc and c-fos expression in melanoma cells respectively. These results clearly indicate that the combination of 8-Cl-cAMP and tiazofurin could provide a promising therapeutic approach for melanoma treatment

Synthesis and Biological Screening of New 4-Hydroxycoumarin Derivatives and Their Palladium(II) Complexes

Two newly synthesized 4-hydroxycoumarin bidentate ligands (L1 and L2) and their palladium(II) complexes (C1 and C2) were screened for their biological activities, in vitro and in vivo. Structures of new compounds were established based on elemental analysis, 1H NMR, 13C NMR, and IR spectroscopic techniques. The obtained compounds were tested for their antioxidative and cytotoxic activities and results pointed to selective antiradical activity of palladium(II) complexes towards •OH and -•OOH radicals and anti-ABTS (2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical) activity comparable to that of ascorbate. Results indicated the effect of C1 and C2 on the enzymatic activity of the antioxidative defense system. In vitro cytotoxicity assay performed on different carcinoma cell lines (HCT166, A375, and MIA PaCa-2), and one healthy fibroblast cell line (MRC-5) showed a cytotoxic effect of both C1 and C2, expressed as a decrease in carcinoma cells’ viability, mostly by induction of apoptosis. In vivo toxicity tests performed on zebrafish embryos indicated different effects of C1 and C2, ranging from adverse developmental effect to no toxicity, depending on tested concentration. According to docking studies, both complexes (C1 and C2) showed better inhibitory activity in comparison to other palladium(II) complexes