Fullerene C60 Penetration into Human Leukemic Cells and its Photoinduced Cytotoxic Effects
D. Franskevych, K. Palyvoda, D. Petukhov, S. Prylutska, I. Grynyuk, C. Schuetze, L. Drobot, O. Matyshevska and U. Ritter
Nanoscale Research Letters (2017)
Summary:
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.
Conclusion:
In this study, stable homogenous water colloid solution of pristine fullerene C60 was used in experiments for estimation of C60 photocytotoxicity on leukemic cells.
C60-RITC conjugate was synthesized for monitoring C60 entry into leukemic cells by confocal microscopy. Leukemic Jurkat cells could uptake fullerene C60 from the medium and retain the accumulated nanoparticles over 18 h. Combined treatment with C60 and visible light is followed by timedependent decrease of Jurkat cell viability.
Inhibition of protein tyrosine phosphorylation could be one of the mechanisms of C60 photocytotoxic effects realization. C60-mediated photodynamic effect was demonstrated also on leukemic L1210 cells both sensitive and resistant to cisplatin. Decrease of drug-resistant cell viability after C60 photoexcitation corresponded to a significant drop of mitochondrial potential.
The data obtained allow to suggest that C60 photodynamic treatment might be a potential strategy for restoring the drug-resistant leukemic cell sensitivity to induction of mitochondrial way of apoptosis.
Study analysis
Further to the study's findings, the implications of fullerene C60's photodynamic treatment on leukemic cells, especially those resistant to cisplatin, cannot be understated. The potential for this carbon nano compound, with its exceptional physicochemical properties, to make significant strides in cancer therapy is substantial. The fact that C60's cytotoxic effect is brought into force upon photoexcitation, causing a significant decrease of cell viability, is compelling evidence of a novel way to combat leukaemia.
Furthermore, the effect of C60-mediated photodynamic therapy on protein tyrosine phosphorylation reveals an intriguing avenue for exploration. The possibility of fullerene C60 inhibiting this essential cell function may elucidate the mechanisms behind the compound's cytotoxic effects. The correlation between this effect and decreased cell viability necessitates further research into the intricacies of C60's interaction with cell proteins.
Overall, this pioneering study on fullerene C60 introduces new horizons for photodynamic therapy, offering a beacon of hope for leukaemia treatment and potentially changing the trajectory of oncological research. Significantly, the C60 photodynamic treatment shows promise in re-sensitizing drug-resistant leukemic cells, reviving their susceptibility to apoptosis induction via mitochondrial pathways. This is a critical area of cancer therapy research that demands further investigation.
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