title: beta(2)-microglobulin induces apoptosis in HL-60 human leukemia cell line and its multidrug resistant variants overexpressing MRP1 but lacking Bax or overexpressing P-glycoprotein.
abstract: In this study, we examined whether exogenous beta(2)-microglobulin (beta(2)m) can induce apoptosis in the drug sensitive HL-60 leukemia cell line and its drug resistant variants and investigated the molecular mechanism of beta(2)m-induced apoptosis. Our data revealed that beta(2)m is very significantly down-regulated in two multidrug resistant variants of the HL-60 cells: (a) the MRP1-bearing, Bax-deficient HL-60/ADR cell line, and (b) the P-glycoprotein (P-gp) overexpressing HL-60/VCR cell line. However, exogenous beta(2)m induced similar levels of apoptosis in HL-60 cells and these drug resistant variants. beta(2)m-induced apoptosis in HL-60 and HL-60/VCR cells was associated with decreased mitochondrial membrane potential (Deltapsim) but did not affect Deltapsim in HL-60/ADR cells. Surprisingly, cyclosporin A (CsA), a known inhibitor of the mitochondrial permeability transition (MPT) pore, inhibited beta(2)m-induced apoptosis in HL-60/ADR cells but not in HL-60 and HL-60/VCR cells, suggesting that the pro-apoptotic effect of beta(2)m in these cells is not through MPT pore formation. Furthermore, beta(2)m induced the release of cytochrome c and the apoptosis-inducing factor (AIF) from mitochondria in HL-60 and HL-60/VCR cells, but not in HL-60/ADR cells. Additionally, Z-VAD-fmk, a general inhibitor of caspases which inhibited cytochrome c release in HL-60 and HL-60/VCR cells, had no effect on AIF release in any of these cell lines, but inhibited beta(2)m-induced apoptosis in all three cell lines. However, Western blot analysis revealed that caspases-1, -3, -6, -8, and -9 are not activated during beta(2)m-induced apoptosis in these cells. Therefore, beta(2)m-induces apoptosis through an unknown caspase-dependent mitochondrial pathway in HL-60 and HL-60/VCR cells and by a Bax-independent, non-mitochondrial, caspase-dependent pathway in HL-60/ADR cells.
authors.affiliation: Department of Pharmacology and Toxicology, Indiana University 1044 West Walnut R4-119, Indianapolis, Indiana, IN 46202, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Rastegar
authors.forename: J
authors.initials: J
authors.lastname: Gordon
authors.forename: A R
authors.initials: AR
authors.lastname: Safa
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D051033:Apoptosis Inducing Factor; D016572:Cyclosporine / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple / Q000235:genetics / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000235:genetics / Q000502:physiology*; D005420:Flavoproteins / Q000378:metabolism; D015973:Gene Expression Regulation, Leukemic; D018922:HL-60 Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007473:Ion Channels; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D008928:Mitochondria / Q000502:physiology; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D009363:Neoplasm Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D014747:Vinblastine / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology; D051028:bcl-2-Associated X Protein; D001613:beta 2-Microglobulin / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; D051033:Apoptosis Inducing Factor; D016572:Cyclosporine; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D004268:DNA-Binding Proteins; D004317:Doxorubicin; D005420:Flavoproteins; D007473:Ion Channels; D008565:Membrane Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D000074081:MutS Homolog 3 Protein; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D014747:Vinblastine; D014750:Vincristine; D051028:bcl-2-Associated X Protein; D001613:beta 2-Microglobulin; C494829:AIFM1 protein, human; C494826:BAX protein, human; C078444:MSH3 protein, human; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C421109:multidrug resistance-associated protein 1