title: Inhibition of caspase proteases by CrmA enhances the resistance of human leukemic cells to multiple chemotherapeutic agents.
abstract: Proteases that are members of the caspase (or interleukin-1beta converting enzyme (ICE)) protease family have been shown to be important mediators of apoptosis induced by Fas activation, neurotrophic factor withdrawal, and detachment from extracellular matrix. In this report we have investigated the potential importance of caspase proteases in apoptosis induced by multiple chemotherapeutic agents. Human T leukemic cells engineered to overexpress the cowpox virus CrmA protein, a direct and specific inhibitor of caspase proteases, were studied for their resistance to 1-beta-D-arabinofurasosyl-cytosine (Ara-C), etoposide (VP-16), doxorubicin (DOX), and cis-dichlorodiammine platinum (CP). Overexpression of CrmA dramatically inhibited drug-induced activation of caspases, as measured by processing of the inactive precursor form of caspase-3 and cleavage of caspase substrate proteins poly(ADP-ribose) polymerase (PARP) and lamin B. CrmA also significantly inhibited the kinetics of cell death induced by each of the four drugs. Moreover, when examined several days or weeks after initial exposure to drug, cultures of CrmA-expressing cells were found to have recovered and repopulated, whereas vector-transfected control cells did not. These studies demonstrate that caspase proteases play an important role in conferring sensitivity to multiple chemotherapy drugs, and that constitutive downmodulation of caspase activities can enhance chemoresistance.
authors.affiliation: Department of Medicine, University of Pittsburgh, and the University of Pittsburgh Cancer Institute, PA 15213-2582, USA.
authors.forename: K
authors.initials: K
authors.lastname: Antoku
authors.forename: Z
authors.initials: Z
authors.lastname: Liu
authors.forename: D E
authors.initials: DE
authors.lastname: Johnson
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D020170:Caspase 1; D002945:Cisplatin / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000187:drug effects* / Q000378:metabolism; D003561:Cytarabine / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005047:Etoposide / Q000494:pharmacology; D006801:Humans; D034921:Lamin Type B; D034882:Lamins; D015458:Leukemia, T-Cell / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D015843:Serpins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014764:Viral Proteins
chemical_list: D000970:Antineoplastic Agents; D034921:Lamin Type B; D034882:Lamins; D009687:Nuclear Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D015843:Serpins; D014764:Viral Proteins; D003561:Cytarabine; D005047:Etoposide; D004317:Doxorubicin; C074641:interleukin-1beta-converting enzyme inhibitor; D011065:Poly(ADP-ribose) Polymerases; D003546:Cysteine Endopeptidases; D020170:Caspase 1; D002945:Cisplatin