Contributions
Abstract: PB1622
Type: Publication Only
Background
Epigallocatechine-3-gallate (EGCG) and menadione (vitamin K3; MD) are known as potent apoptogens in cellular models for acute lymphoblastic leukemia (ALL) –Jurkat T cells.
Aims
The goal of this study was to explore the chemotherapeutic potential of MD combined with EGCG or DOX, and to determine whether there is a synergic interaction between these agents that could significantly enhance their antitumoral effect in a cellular model of ALL. We investigated the antiproliferative effect of EGCG and MD, applied alone or in combination EGCG:MD and MD:DOX respectively on human leukemia Jurkat lymphoblasts. Some underlying cellular mechanisms were also scrutinized.
Methods
Results
EGCG decreased clonogenic survival (IC50=117 µM and Hill coefficient h=3.17) and mitochondrial calcium in a dose-dependent manner (IC50 =97 µM, h=2.53). Furthermore, data show that there is no correlation between the level of mitochondrial calcium ([Ca2+]m) and mitochondrial membrane potential (Δψm) (Pearson correlation coefficient r= −0.100) or between [Ca2+]m and reactive oxygen speacies (r = −0.437) production, thus EGCG exerted a depolarizing effect at the mitochondrial level, most likely via interference with the opening of the mitochondrial permeability transition pore. The combination EGCG:MD induced cell cycle arrest in G2/M and S phases in a synergic manner (the measured viability was: ~91% for EGCG 50 µM, ~72%MD 25 µM, ~20% for their combination). The existence of two binding sites for EGCG is suggested, both modulated by MD, implying that MD is an allosteric modulator of the EGCG-induced depolarization. Fluorescence induced by treatment with EGCG alone, MD alone and EGCG:MD in combination was 172%, 101% and 387%, respectively, suggesting that EGCG and MD interact with the second specific target in a synergic manner. DOX induced cell cycle arrest, and clinical doses of DOX generated oxidative stress. MD augmented this effect, enhancing the antiproliferative effect of DOX most likely by increasing the affinity of DOX for nuclear DNA.
Conclusion
Our results support the notion that the combinations EGCG:MD and MD:DOX exert a strong synergic antiproliferative effect in human leukemia Jurkat cells and encourage further studies to test the clinical utility of this association in ALL therapy.
Session topic: 1. Acute lymphoblastic leukemia - Biology
Keyword(s): Synergy, Doxorubicin, Apoptosis, Acute lymphoblastic leukemia
Abstract: PB1622
Type: Publication Only
Background
Epigallocatechine-3-gallate (EGCG) and menadione (vitamin K3; MD) are known as potent apoptogens in cellular models for acute lymphoblastic leukemia (ALL) –Jurkat T cells.
Aims
The goal of this study was to explore the chemotherapeutic potential of MD combined with EGCG or DOX, and to determine whether there is a synergic interaction between these agents that could significantly enhance their antitumoral effect in a cellular model of ALL. We investigated the antiproliferative effect of EGCG and MD, applied alone or in combination EGCG:MD and MD:DOX respectively on human leukemia Jurkat lymphoblasts. Some underlying cellular mechanisms were also scrutinized.
Methods
Results
EGCG decreased clonogenic survival (IC50=117 µM and Hill coefficient h=3.17) and mitochondrial calcium in a dose-dependent manner (IC50 =97 µM, h=2.53). Furthermore, data show that there is no correlation between the level of mitochondrial calcium ([Ca2+]m) and mitochondrial membrane potential (Δψm) (Pearson correlation coefficient r= −0.100) or between [Ca2+]m and reactive oxygen speacies (r = −0.437) production, thus EGCG exerted a depolarizing effect at the mitochondrial level, most likely via interference with the opening of the mitochondrial permeability transition pore. The combination EGCG:MD induced cell cycle arrest in G2/M and S phases in a synergic manner (the measured viability was: ~91% for EGCG 50 µM, ~72%MD 25 µM, ~20% for their combination). The existence of two binding sites for EGCG is suggested, both modulated by MD, implying that MD is an allosteric modulator of the EGCG-induced depolarization. Fluorescence induced by treatment with EGCG alone, MD alone and EGCG:MD in combination was 172%, 101% and 387%, respectively, suggesting that EGCG and MD interact with the second specific target in a synergic manner. DOX induced cell cycle arrest, and clinical doses of DOX generated oxidative stress. MD augmented this effect, enhancing the antiproliferative effect of DOX most likely by increasing the affinity of DOX for nuclear DNA.
Conclusion
Our results support the notion that the combinations EGCG:MD and MD:DOX exert a strong synergic antiproliferative effect in human leukemia Jurkat cells and encourage further studies to test the clinical utility of this association in ALL therapy.
Session topic: 1. Acute lymphoblastic leukemia - Biology
Keyword(s): Synergy, Doxorubicin, Apoptosis, Acute lymphoblastic leukemia