title: Acadesine activates AMPK and induces apoptosis in B-cell chronic lymphocytic leukemia cells but not in T lymphocytes.
abstract: Acadesine, 5-aminoimidazole-4-carboxamide (AICA) riboside, induced apoptosis in B-cell chronic lymphocytic leukemia (B-CLL) cells in all samples tested (n = 70). The half-maximal effective concentration (EC(50)) for B-CLL cells was 380 +/- 60 microM (n = 5). The caspase inhibitor Z-VAD.fmk completely blocked acadesine-induced apoptosis, which involved the activation of caspase-3, -8, and -9 and cytochrome c release. Incubation of B-CLL cells with acadesine induced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), indicating that it is activated by acadesine. Nitrobenzylthioinosine (NBTI), a nucleoside transport inhibitor, 5-iodotubercidin, an inhibitor of adenosine kinase, and adenosine completely inhibited acadesine-induced apoptosis and AMPK phosphorylation, demonstrating that incorporation of acadesine into the cell and its subsequent phosphorylation to AICA ribotide (ZMP) are necessary to induce apoptosis. Inhibitors of protein kinase A and mitogen-activated protein kinases did not protect from acadesine-induced apoptosis in B-CLL cells. Moreover, acadesine had no effect on p53 levels or phosphorylation, suggesting a p53-independent mechanism in apoptosis triggering. Normal B lymphocytes were as sensitive as B-CLL cells to acadesine-induced apoptosis. However, T cells from patients with B-CLL were only slightly affected by acadesine at doses up to 4 mM. AMPK phosphorylation did not occur in T cells treated with acadesine. Intracellular levels of ZMP were higher in B-CLL cells than in T cells when both were treated with 0.5 mM acadesine, suggesting that ZMP accumulation is necessary to activate AMPK and induce apoptosis. These results suggest a new pathway involving AMPK in the control of apoptosis in B-CLL cells and raise the possibility of using acadesine in B-CLL treatment.
authors.affiliation: Unitat de Bioquimica, Departament de Ciències Fisiològiques II, Universitat de Barcelona, Campus de Bellvitge, E-08907 L'Hospitalet de Llobregat, Spain.
authors.forename: Clara
authors.initials: C
authors.lastname: Campàs
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Lopez
authors.forename: Antonio F
authors.initials: AF
authors.lastname: Santidrián
authors.forename: Montserrat
authors.initials: M
authors.lastname: Barragán
authors.forename: Beatriz
authors.initials: B
authors.lastname: Bellosillo
authors.forename: Dolors
authors.initials: D
authors.lastname: Colomer
authors.forename: Joan
authors.initials: J
authors.lastname: Gil
mesh_terms: D055372:AMP-Activated Protein Kinases; D000241:Adenosine / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000201:enzymology / Q000473:pathology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009097:Multienzyme Complexes / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012263:Ribonucleosides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D012265:Ribonucleotides / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology; D014372:Tubercidin / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000473:pathology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000964:Antimetabolites, Antineoplastic; D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D009097:Multienzyme Complexes; D009363:Neoplasm Proteins; D012263:Ribonucleosides; D012265:Ribonucleotides; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; C034214:5-iodotubercidin; D000620:Aminoimidazole Carboxamide; C011651:acadesine; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D055372:AMP-Activated Protein Kinases; D020169:Caspases; C031143:AICA ribonucleotide; D000241:Adenosine; D014372:Tubercidin