Cytotoxicity Of Cu Research Articles

New Simple Synthesis of Cu–TiO2 Nanocomposite: Highly Enhanced Photocatalytic Killing of Epithelia Carcinoma (HeLa) Cells

Abstract Cu–TiO2 nanocomposites with different Cu/TiO2 molar ratios were synthesized by a new simple chemical reduction method. The morphological structure and the surface species of Cu–TiO2 nanocomposites were determined by using UV–vis absorption spectroscopy, TEM, XPS, XRD, and EDX techniques. The photocatalytic cytotoxicity of Cu–TiO2 nanocomposites was investigated under UV–vis light irradiation. The cytotoxicity depends on the molar ratio of Cu to TiO2, ranging from 0.2 to 5.

Influence of copper (II) ions and its derivatives on radiosensitivity of Escherichia coli

In an attempt to explore potential of Cu(II) ions and its synthetic aminocarboxylic complexes as radiosensitizers in cellular systems, we sought to follow the influence of these substances on radiosensitivity of Escherichia coli K12 strain. Cytotoxicity of Cu(II) ions could be reduced significantly by sequestering with the suitable aminocarboxylic chelating agents. The dose dependent cell survival, in the absence and the presence of additives, was monitored by cell inactivation assay. Extent of DNA damage in the process of radiosensitization was determined using fluorimetric technique. It was observed that Cu 2+ ions radiosensitize the cells. Among the three complexes studied, Cu-NTA (nitrilo triacetic acid) can enter into cells and can radiosensitize the same. Structure of metal complex and the presence of electron affinic site(s) play an important role in its cellular incorporation and to function as radiosensitizer. The present study indicates that Cu-NTA may be considered a suitable model for development of radiosensitizing metal complexes.

Oxidative stress is involved in inhibition of copper on histone acetylation in cells

Our previous study demonstrates that copper induces histone hypoacetylation by inhibiting histone acetyltransferase (HAT) activity. However, it lacks direct evidences whether copper-inhibited histone acetylation right contributes to the toxicity of copper. Exposure of human leukemia cells (HL-60) to Cu 2+ resulted in cell proliferation arrest and a concentration- and time-dependent decrease of histone acetylation. At the same time, Cu 2+-induced significant increase of H 2O 2 and O 2 − generation via a concentration- and time-dependent manner too. The histone acetylation was efficiently suppressed by exogenous H 2O 2, and enhanced by superoxide dismutase (the scavenger of O 2 −), catalase (the scavenger of H 2O 2) or the combination of both, indicating that Cu 2+ at least partially inhibited histone acetylation through triggering oxidative stress. Further studies found that sodium butyrate, the inhibitor of histone deacetylase (HDAC), which had no obvious effect on oxidative stress but increased histone acetylation at the concentration of 50 μM, attenuated Cu 2+-inhibited cell proliferation, indicating that histone acetylation inhibition is simultaneously involved in the cytotoxicity of Cu 2+. Considering the important role of histone acetylation in gene transcription and regulation of cell fate, the present study may open a new door to further understand the mechanism of Cu 2+-induced toxicity.

BINDING AND CYTOTOXICITY OF CERATO-ULMIN TO ELM CELLS

In vitro cultivated elm cells were used to study the cytotoxicity of cerato-ulmin (= CU), a hydrophobin produced by Ophiostoma ulmi and O. novo-ulmi, two causal agents of Dutch elm disease (= DED). Purified CU was found to bind to elm cells and cause a dose-dependent death both on cells derived from a DED susceptible (C06) and a moderately resistant (196/6) elm clone. Indirect immunofluorescence (IF) tests, using a rabbit anti-CU antiserum, indicated that homogeneous CU binds to elm but not to cells of fennel and pear, two non-host species of Ophiostoma. The binding was demonstrated by quantitative ELISA on extracts from elm cells incubated with purified CU and by measuring the decrease in CU concentration in the incubation mixture. The equation of the saturation binding curve indicated that the maximum quantity of bound CU for elm clones C06 and 196/6 were similar (351.92 and 355.59 pmoles mg-1 d.wt. elm cells, respectively), as similar were the equilibrium dissociation constants (7.09 and 8.08 µM CU, respectively). The increase in bound CU correlated with the intensity of the fluorescence signal on elm cells and a higher mortality. Elm cell-Ophiostoma spp. dual cultures in Takai or Murashige & Skoogderived media were used to test the ability of elm cells to support growth of Ophiostoma fungi and CU production. Cells derived from two elm clones supported both abundant fungal growth and CU production. Fungal growth was supported by cells of the Ophiostoma nonhosts fennel and pear, whereas CU was only produced in the presence of fennel cells. The binding and direct cytotoxicity of CU on elm cells support its role as a pathogenicity factor in DED.