title: The histone deacetylase inhibitor MGCD0103 induces apoptosis in B-cell chronic lymphocytic leukemia cells through a mitochondria-mediated caspase activation cascade.
abstract: Clinical trials have shown activity of the isotype-selective histone deacetylase (HDAC) inhibitor MGCD0103 in different hematologic malignancies. There are data to support the use of HDAC inhibitors in association with other cancer therapies. To propose a rational combination therapy, it is necessary to depict the molecular basis behind the cytotoxic effect of MGCD0103. In this study, we found that MGCD0103 was substantially more toxic in neoplastic B cells relative to normal cells, and we described the death pathways activated by MGCD0103 in B-cell chronic lymphocytic leukemia (CLL) cells from 32 patients. MGCD0103 decreased the expression of Mcl-1 and induced translocation of Bax to the mitochondria, mitochondrial depolarization, and release of cytochrome c in the cytosol. Caspase processing in the presence of the caspase inhibitor Q-VD-OPh and time course experiments showed that caspase-9 was the apical caspase. Thus, MGCD0103 induced the intrinsic pathway of apoptosis in CLL cells. Moreover, MGCD0103 treatment resulted in the activation of a caspase cascade downstream of caspase-9, caspase-dependent amplification of mitochondrial depolarization, activation of calpain, and Bax cleavage. We propose a model whereby the intrinsic pathway of apoptosis triggered by MGCD0103 in CLL is associated with a mitochondrial death amplification loop.
authors.affiliation: Laboratory of Experimental Hemato-Oncology, Public Research Center for Health (CRP-Santé), Luxembourg, Luxembourg. victoria.elkhoury@crp-sante.lu
authors.forename: Victoria
authors.initials: V
authors.lastname: El-Khoury
authors.forename: Etienne
authors.initials: E
authors.lastname: Moussay
authors.forename: Bassam
authors.initials: B
authors.lastname: Janji
authors.forename: Valérie
authors.initials: V
authors.lastname: Palissot
authors.forename: Nasséra
authors.initials: N
authors.lastname: Aouali
authors.forename: Nicolaas H C
authors.initials: NH
authors.lastname: Brons
authors.forename: Kris
authors.initials: K
authors.lastname: Van Moer
authors.forename: Sandrine
authors.initials: S
authors.lastname: Pierson
authors.forename: Eric
authors.initials: E
authors.lastname: Van Dyck
authors.forename: Guy
authors.initials: G
authors.lastname: Berchem
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism*; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D011743:Pyrimidines / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D056572:Histone Deacetylase Inhibitors; D011743:Pyrimidines; C523184:mocetinostat; D020169:Caspases