title: 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.
abstract: 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-beta-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-beta-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(2)O(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.
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sánchez
authors.forename: Consuelo
authors.initials: C
authors.lastname: Calle
authors.forename: Elena
authors.initials: E
authors.lastname: de Blas
authors.forename: Patricio
authors.initials: P
authors.lastname: Aller
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D004357:Drug Synergism; D004789:Enzyme Activation; D004958:Estradiol / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D006873:Hydroquinones / Q000494:pharmacology; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010087:Oxides / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020298:U937 Cells
chemical_list: D000970:Antineoplastic Agents; D000975:Antioxidants; D001152:Arsenicals; D006873:Hydroquinones; C404397:NSC 680410; D010087:Oxides; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D004958:Estradiol; D005047:Etoposide; D002392:Catechin; C045651:epigallocatechin gallate; D019833:Genistein; D020928:Mitogen-Activated Protein Kinases; D000218:Adamantane; D000077237:Arsenic Trioxide