title: Differential induction of apoptosis and MAP kinase signaling by mitochondrial toxicants in drug-sensitive compared to drug-resistant B-lineage lymphoid cell lines.
abstract: A panel of human B-lineage lymphoma cell lines differing in cancer drug-resistance status and Bcl-2/Bax expression were used to study the contribution of mitochondrial-based perturbations and regulation in differential induction of apoptosis. Mitochondrial dysfunction was induced in cells by the uncoupler carbonyl cyanide m-chlorophenylhydrazone (mClCCP) and the respiratory chain inhibitor antimycin A. Cells were then assayed for early changes in MAP kinase signaling and subsequent induction of apoptosis. The cancer drug-resistant cell lines EW36 and CA46, overexpressing Bcl-2 and deficient in Bax, respectively, were both resistant to mitochondrial toxicant-induced cleavage of poly(ADP-ribose) polymerase (PARP) and morphologically detectable apoptotic cell death. In contrast, cancer drug-sensitive ST486 cell line, with low Bcl-2 expression, was sensitive to PARP cleavage and apoptosis engagement. Interestingly, mClCCP induced twofold more apoptosis than antimycin A in the ST486 cells. Exposure to the mitochondrial toxicants resulted in the early and preferential activation of the ERK and p38 MAP kinase pathways in only the drug-sensitive ST486 cell line, with mClCCP more potent than antimycin A. Specific inhibition of the p38 pathway augmented baseline and mClCCP-induced apoptosis. These results show that multi-drug-resistant and -sensitive B-lineage cells are also resistant and sensitive to compounds inducing mitochondrial dysfunction. The differential sensitivity to mitochondrial toxicant effects involved regulation by MAP kinases, since ERK and p38 were found to be preferentially activated only in the drug-sensitive B-lineage cells. Modulation of the p38 signaling pathway altered the sensitivity of cells to mitochondrial stress and may play a more general role in regulating the sensitivity of B-lineage cells to drugs and environmental toxicants.
authors.affiliation: Department of Microbiology and Immunology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: O'Brien
authors.forename: D E
authors.initials: DE
authors.lastname: Muscarella
authors.forename: S E
authors.initials: SE
authors.lastname: Bloom
mesh_terms: D000968:Antimycin A / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001402:B-Lymphocytes / Q000187:drug effects* / Q000502:physiology; D002051:Burkitt Lymphoma; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D016923:Cell Death; D004351:Drug Resistance; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000172:deficiency; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000187:drug effects*; D014475:Uncoupling Agents / Q000494:pharmacology; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000970:Antineoplastic Agents; C494826:BAX protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014475:Uncoupling Agents; D051028:bcl-2-Associated X Protein; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000968:Antimycin A; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases