Fullerene C60 as a representative of carbon nanocompounds is suggested to be promising agent for application in photodynamic therapy due to its unique physicochemical properties. The goal of this study was to estimate the accumulation of fullerene C60 in leukemic cells and to investigate its phototoxic effect on parental and resistant to cisplatin leukemic cells. Stable homogeneous water colloid solution of pristine C60 with average 50-nm diameter of nanoparticles was used in experiments. Fluorescent labeled C60 was synthesized by covalent conjugation of C60 with rhodamine B isothiocyanate. The results of confocal microscopy showed that leukemic Jurkat cells could effectively uptake fullerene C60 from the medium. Light-emitting diode lamp (100 mW cm−2, λ = 420–700 nm) was used for excitation of accumulated C60. A time-dependent decrease of viability was detected when leukemic Jurkat cells were exposed to combined treatment with C60 and visible light. The cytotoxic effect of photoexcited C60 was comparable with that induced by H2O2, as both agents caused 50% decrease of cell viability at 24 h at concentrations about 50 μM. Using immunoblot analysis, protein phosphotyrosine levels in cells were estimated. Combined action of C60 and visible light was followed by decrease of cellular proteins phosphorylation on tyrosine residues though less intensive as compared with that induced by H2O2 or protein tyrosine kinase inhibitor staurosporine. All tested agents reduced phosphorylation of 55, 70, and 90 kDa proteins while total suppression of 26 kDa protein phosphorylation was specific only for photoexcited C60. The cytotoxic effect of C60 in combination with visible light irradiation was demonstrated also on leukemic L1210 cells both sensitive and resistant to cisplatin. It was shown that relative value of mitochondrial membrane potential measured with tetramethylrhodamine ethyl ester perchlorate (TMRE) probe was lower in resistant cells in comparison with sensitive cells and the drop of mitochondrial potential corresponded to further decrease of resistant cell viability after C60 photoexcitation. The data obtained allow to suggest that C60-mediated photodynamic treatment is a candidate for restoration of drug-resistant leukemic cell sensitivity to induction of mitochondrial way of apoptosis.

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Fullerene C 60 Penetration into Leukemic Cells and Its Photoinduced Cytotoxic Effects

Nanoparticles of fullerenes and their water-soluble derivatives have been firmly introduced into solution of medical problems. Although there are still debates about their toxicity and long-term consequences of their application in the clinic, the success of fullerenes application in some sections is undeniable, in particular, in photodynamic therapy (PDT) of cancer tumors. Besides there are interesting data on radiotherapy where fullerenes appear to be more transporters than drugs, but due to own cytoprotective properties, the fullerene adducts can also participate in the combined treatment. This review evaluates the status of these sections of fullerene chemistry in terms of development and recent trends.

Perspectives of fullerene derivatives in PDT and radiotherapy of cancers.

A nanosized drug complex was explored to improve the efficiency of cancer chemotherapy, complementing it with nanodelivery and photodynamic therapy. For this, nanomolar amounts of a non-covalent nanocomplex of Doxorubicin (Dox) with carbon nanoparticle C60 fullerene (C60) were applied in 1:1 and 2:1 molar ratio, exploiting C60 both as a drug-carrier and as a photosensitizer. The fluorescence microscopy analysis of human leukemic CCRF-CEM cells, in vitro cancer model, treated with nanocomplexes showed Dox’s nuclear and C60’s extranuclear localization. It gave an opportunity to realize a double hit strategy against cancer cells based on Dox’s antiproliferative activity and C60’s photoinduced pro-oxidant activity. When cells were treated with 2:1 C60-Dox and irradiated at 405 nm the high cytotoxicity of photo-irradiated C60-Dox enabled a nanomolar concentration of Dox and C60 to efficiently kill cancer cells in vitro. The high pro-oxidant and pro-apoptotic efficiency decreased IC50 16, 9 and 7 × 103-fold, if compared with the action of Dox, non-irradiated nanocomplex, and C60’s photodynamic effect, correspondingly. Hereafter, a strong synergy of therapy arising from the combination of C60-mediated Dox delivery and C60 photoexcitation was revealed. Our data indicate that a combination of chemo- and photodynamic therapies with C60-Dox nanoformulation provides a promising synergetic approach for cancer treatment.

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Synergy of Chemo- and Photodynamic Therapies with C60 Fullerene-Doxorubicin Nanocomplex.

Nanoparticles of fullerenes and their water -soluble derivatives have been firmly introduced into solution of medical problems. Although there are still debat

Perspectives of Fullerene DerivativesinPDT and Radiotherapy of Cancers

Involvement of heme oxygenase-1 in neuroprotection by sanguinarine against glutamate-triggered apoptosis in HT22 neuronal cells

The viability of normal (Wistar rat thymocytes) and transformed (human leukemia Jurkat cells) T cells after UV/Vis irradiation in the presence of pristine C60 fullerene was studied. The data obtained have shown that C60 fullerene exhibits cytotoxic effect against transformed T lymphocytes when combined with UV/Vis irradiation using mercury-vapor lamp (320-600 nm). C60 fullerene photocytotoxicity was not detected in thymocytes. C60-dependent photoinduced apoptosis of Jurkat cells was confirmed by DNA fragmentation and caspase-3 activation. No substantial increase of caspase-3 activation was observed in thymocytes treated with C60 fullerene plus irradiation, while antileukemic agent cytosine arabinoside was shown to induce caspase-3 activation both in Jurkat cells and thymocytes. The data obtained may be useful for development of photosensitizers for photodynamic therapy with selective action on leukemia cells.

Apoptosis photoinduction by C60 fullerene in human leukemic T cells.

The values of endoplasmic reticulum Ca(2+)-pool and store-operated Ca2+ entry (SOCE) were estimated in rat thymocytes and Jurkat cells loaded with indo-1 and treated with thapsigargin. It was shown that the relative value of SOCE in thymocytes was substantially lower than in Jurkat cells. Significant increase of SOCE in Jurkat cells preincubated with 10(-5) M C60 and exposed to uv/visible light irradiation was detected at 1-3 h after exposure. At this time FCCP-induced Ca(2+)-release from mitochondria was shown to be reduced, while cytochrome c level into the cytoplasm of Jurkat cells, detected by Western blot analysis, to be increased. It is supposed that Ca2+ flux remodulation induced by photoexcited fullerene C60 in Jurkat cells might be involved in the initiation of signalling events leading to cell apoptosis.

A A Samoylenko

Papers

Apoptosis photoinduction by C60 fullerene in human leukemic T cells.

Photoactivated fullerene C60 induces store-operated Ca2 entry and cytochrome c release in Jurkat cells.