Modulation of arsenic trioxide-induced apoptosis by genistein and functionally related agents in U937 human leukaemia cells. Regulation by ROS and mitogen-activated protein kinases

• Published in: Chemico-biological interactions 2009-11, Vol.182 (1), p.37-44
• Main Authors: Sánchez, Yolanda, Calle, Consuelo, de Blas, Elena, Aller, Patricio
• Format: Article
• Language: English
• Subjects: Adamantane - analogs & derivatives; Adamantane - pharmacology; Antineoplastic Agents - pharmacology; Antioxidants - pharmacology; Apoptosis; Apoptosis - drug effects; Arsenic trioxide; Arsenicals - pharmacology; Catechin - analogs & derivatives; Catechin - pharmacology; Cell Cycle - drug effects; Drug Synergism; Enzyme Activation; Estradiol - pharmacology; Etoposide - pharmacology; Genistein; Genistein - pharmacology; HL-60 Cells; Humans; Hydroquinones - pharmacology; Immunoblotting; Microscopy, Fluorescence; Mitogen-activated protein kinases; Mitogen-Activated Protein Kinases - antagonists & inhibitors; Mitogen-Activated Protein Kinases - metabolism; Oxides - pharmacology; Protein Kinase Inhibitors - pharmacology; Reactive Oxygen Species - metabolism; RNA, Small Interfering - pharmacology; Tyrosine kinase inhibitors; U937 Cells; U937 leukaemia cells
• ISSN: 0009-2797; 1872-7786
• DOI: 10.1016/j.cbi.2009.08.015

The proved radio- and chemo-sensitizing capacity of genistein supports the potential use of this isoflavone in antitumour therapies. In this regard, we recently reported that genistein potentiates apoptosis induction by the anti-leukaemic agent arsenic trioxide (ATO) via reactive oxygen species (ROS) generation and p38-MAPK activation. In the present study we analyze the action of agents sharing functional similarities with the isoflavone, namely 17-β-estradiol, the DNA topoisomerase II poison etoposide, and the tyrosine kinase (PTK) inhibitors herbimycin A, epigallocatechin-3-gallate (EGCG) and adaphostin, in U937 and other human acute myeloid leukaemia cell lines. Co-treatment with 17-β-estradiol or etoposide failed to stimulate ROS production and potentiate ATO-provoked apoptosis, although etoposide caused G 2/M cycle arrest, in the same manner as genistein. By contrast, all PTK inhibitors increased ATO-provoked apoptosis, with similar efficacy as genistein. Daidzein, a genistein analogue without PTK-inhibiting activity, failed to potentiate apoptosis, and co-treatment with orthovanadate attenuated the sensitizing capacity of genistein. Apoptosis potentiation by PTK inhibitors was associated to ROS over-accumulation and stimulation of p38-MAPK phosphorylation, was mimicked by conventional pro-oxidant agents (exogenous H 2O 2 and the glutathione-depleting agent dl-buthionine-( S, R)-sulfoximine), and was attenuated by the antioxidant agent N-acetyl- l-cysteine, and by the p38-MAPK inhibitor SB203580 or p38-MAPK-directed siRNAs. On the other hand, the PTK inhibitors caused disparate effects on ERK phosphorylation, and co-treatment with the MEK/ERK inhibitor PD98059 enhanced the pro-apoptotic capacity of the PTK inhibitors. These results suggest that PTK inhibition, together with ROS generation and p38-MAPK activation, are responsible for the chemo-sensitizing action of genistein and functionally related agents in leukaemia cells.