Fullerene C60 Penetration into Leukemic Cells and Its Photoinduced Cytotoxic Effects

Abstract

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.

Activation of store – operated Ca(2+) entry in cisplatin resistant leukemic cells after treatment with photoexcited fullerene C(60) and cisplatin

“…Lower TG-sensitive ER Ca 2+ pool content in the presence of photoexcited C 60 and cisplatin could [20].…”

“…As it was previously shown by us with the use of fluorescent labeled C 60 and confocal microscopy, leukemic cells could effectively uptake fullerene C 60 from the medium [20]. Combined treatment of leukemic cells with photoexcited fullerene C 60 and 1 µg/ml cisplatin allowed us to enhance cytotoxic effect and to accelerate cell death of both sensitive and resistant to cisplatin cells as compared with each agent to be used alone [20,21], but the biochemical mechanisms of this effect need further elucidation. A substantial increase of [Ca 2+ ] cyt in leukemic cells which was detected 3 h after combined treatment with photoexcited C 60 and cisplatin [21] could be one of the determining factors in this effect.…”

Fullerenes in biology and medicine

“…79 reported the cytotoxic effect of C 60 in combination with visible light irradiation on leukemic L1210 cell lines, both sensitive and resistant to cisplatin. Their results suggest that C 60 -mediated photodynamic treatment is a good candidate for restoring drug-resistant leukemic cells induced to mitochondrial apoptosis.…”

Influence of C(60) fullerene on the ischemia-reperfusion injury in the skeletal muscle of rat limb: mechanokinetic and biochemical analysis

“…So, C 60 fullerenes behave as "free radical scavengers" and demonstrate antioxidant activity in micromolar concentrations, eliminating both H 2 O 2 and superoxide anions [9,10]. Due to its nearly spherical shape and nanosize, water-soluble C 60 fullerene is capable to penetrate plasma membrane of mammalian cells [11][12][13]. In vitro and in vivo studies of water-soluble pristine C 60 fullerenes had found that these compounds do not possess acute toxicity towards cells and tissues of human organism [14][15][16][17].…”