title: Nilotinib induces apoptosis and autophagic cell death of activated hepatic stellate cells via inhibition of histone deacetylases.
abstract: Increasing hepatic stellate cell (HSC) death is a very attractive approach for limiting liver fibrosis. Tyrosine kinase inhibitors have been shown to have anti-fibrotic properties, but the mechanisms are poorly understood. Here, we identified the mechanism of action of the second-generation tyrosine kinase inhibitor nilotinib in inducing HSC death. Human HSC line (LX-2) and rat HSCs were treated with nilotinib and its predecessor, imatinib, in the absence or presence of various blockers, known to interfere with death signaling pathways. Nilotinib, but not imatinib, induced progressive cell death of activated, but not quiescent, HSCs in a dose-dependent manner. Activated HSCs died through apoptosis, as denoted by increased DNA fragmentation and caspase activation, and through autophagy, as indicated by the accumulation of autophagic markers, light chain (LC)3A-II and LC3B-II. Although inhibition of caspases with Z-VAD-FMK suppressed nilotinib-induced HSCs' apoptosis, there was no increase in HSCs' survival, because autophagy was exacerbated. However, blocking the mitochondrial permeability transition pore (mPTP) opening with cyclosporin A completely abolished both apoptosis and autophagy due to nilotinib. Moreover, nilotinib treatment decreased the protein expression of histone deacetylases 1, 2 and 4. Interestingly, pretreament with C646, a selective p300/CBP histone acetyl transferase inhibitor, resulted in diverting nilotinib-induced apoptosis and autophagy towards necrosis. In conclusion, the identification of mPTP as a target of nilotinib in activated HSCs suggests coordination with histone deacetylases inhibition to induce apoptosis and autophagy. Thus, our study provides novel insights into the anti-fibrotic effects of nilotinib.
authors.affiliation: Department of Internal Medicine, Yale University, New Haven, CT 06520, USA.
authors.forename: Mohamed E
authors.initials: ME
authors.lastname: Shaker
authors.forename: Ayaz
authors.initials: A
authors.lastname: Ghani
authors.forename: Gamal E
authors.initials: GE
authors.lastname: Shiha
authors.forename: Tarek M
authors.initials: TM
authors.lastname: Ibrahim
authors.forename: Wajahat Z
authors.initials: WZ
authors.lastname: Mehal
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D001549:Benzamides / Q000494:pharmacology; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002633:Chemotaxis / Q000187:drug effects / Q000235:genetics; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D000090602:Collagen Type I, alpha 1 Chain; D016572:Cyclosporine / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D000068877:Imatinib Mesylate; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D001549:Benzamides; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D056572:Histone Deacetylase Inhibitors; D008869:Microtubule-Associated Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D053773:Transforming Growth Factor beta1; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016572:Cyclosporine; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D020169:Caspases; D006655:Histone Deacetylases; C498826:nilotinib