title: Synergistic cytotoxic activity of recombinant TRAIL plus the non-genotoxic activator of the p53 pathway nutlin-3 in acute myeloid leukemia cells.
abstract: To potentiate the response of acute myeloid leukemia (AML) to TRAIL cytotoxicity, we have adopted a strategy of combining nutlin-3, a potent non-genotoxic activator of the p53 pathway, with recombinant TRAIL. The rationale for using such a combination was that deletions and/or mutations of the p53 gene occur in only 5-10% of AML and that TRAIL and nutlin-3 activate the extrinsic and intrinsic pathways of apoptosis, respectively. TRAIL induced a rapid increase of apoptosis when added to OCI M4-type and MOLM M5-type AML cells, carrying a wild-type p53, as well as to NB4 M3-type AML, carrying a mutated p53. On the other hand, the small molecule activator of the p53 pathway nutlin-3 induced p53 accumulation, cell cycle arrest and a slow progressive increase of apoptosis in OCI and MOLM but not in NB4. Of note, nutlin-3 up-regulated the surface expression of TRAIL-R2 and synergized with TRAIL in inducing apoptosis in OCI and MOLM as well as in primary M4-type and M5-type AML blasts, but not in NB4 cells. Moreover, while nutlin-3 up-regulated the expression of cyclin dependent kinase inhibitor p21, a p53-target gene mediating cell cycle block and showing anti-apoptotic activity, the simultaneous addition of TRAIL plus nutlin-3 induced the caspase-dependent cleavage of p21. The relevance of p21 down-regulation for sensitizing AML cells to apoptosis was underscored in knocking-down experiments with small interfering RNAs. Our data suggest that the combined treatment of nutlin-3 plus TRAIL might offer a novel therapeutic strategy for AML.
authors.affiliation: Department of Morphology and Embryology, Human Anatomy Section, University of Ferrara, Via Fossato di Mortara 66, 44100 Ferrara, Italy. secchier@mail.umbi.umd.edu
authors.forename: Paola
authors.initials: P
authors.lastname: Secchiero
authors.forename: Carlotta
authors.initials: C
authors.lastname: Zerbinati
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: di Iasio
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Melloni
authors.forename: Mario
authors.initials: M
authors.lastname: Tiribelli
authors.forename: Vittorio
authors.initials: V
authors.lastname: Grill
authors.forename: Giorgio
authors.initials: G
authors.lastname: Zauli
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D009154:Mutation; D010879:Piperazines / Q000494:pharmacology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000187:drug effects / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D050759:Cyclin-Dependent Kinase Inhibitor p21; D007093:Imidazoles; D010879:Piperazines; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; D016159:Tumor Suppressor Protein p53; C482205:nutlin 3; D020169:Caspases