title: Drug resistance towards etoposide and cisplatin in human melanoma cells is associated with drug-dependent apoptosis deficiency.
abstract: Anticancer drugs kill susceptible cells through induction of apoptosis. Alterations of apoptotic pathways in drug-resistant tumor cells leading to apoptosis deficiency might represent a potent mechanism conferring drug resistance. We have assessed the effect of etoposide and cisplatin on the apoptotic pathways of the drug-sensitive human melanoma cell line MeWo as well as its etoposide- and cisplatin-resistant sublines (MeWo(Eto01), MeWo(Eto1), (and) MeWoCis01, MeWo(Cis1)). Etoposide and cisplatin induced apoptosis in drug-sensitive MeWo cells as indicated by dose-dependent (i) cytochrome c release, (ii) caspase activation, (iii) DNA fragmentation, and (iv) cleavage of poly(ADP-ribose)polymerase. In contrast, whereas low etoposide-resistant cells (MeWo(Eto01)) demonstrated reduced but detectable apoptotic activities, highly etoposide-resistant cells (MeWo(Eto1)) did not exhibit any of the apoptotic events observed in etoposide-induced cell death downstream of a strongly reduced cytochrome c release. Highly cisplatin-resistant cells (MeWo(Cis1)), however, demonstrated a reduced caspase 9 activity and cytochrome c release but the extent of effector caspase activation as well as DNA fragmentation was comparable to that of sensitive MeWo cells at equitoxic concentrations. In addition, poly(ADP-ribose)polymerase cleavage was strongly reduced in highly cisplatin-resistant sublines. Taken together, sensitive and drug-resistant MeWo cells utilized different apoptotic pathways upon drug exposure in a drug-dependent fashion and apoptosis deficiency was strongly associated with the drug-resistant phenotype.
authors.affiliation: Skin Cancer Unit at the German Cancer Research Center, University of Heidelberg, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Helmbach
authors.forename: Monika A
authors.initials: MA
authors.lastname: Kern
authors.forename: Evelyn
authors.initials: E
authors.lastname: Rossmann
authors.forename: Kristina
authors.initials: K
authors.lastname: Renz
authors.forename: Christine
authors.initials: C
authors.lastname: Kissel
authors.forename: Brigitte
authors.initials: B
authors.lastname: Gschwendt
authors.forename: Dirk
authors.initials: D
authors.lastname: Schadendorf
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D020169:Caspases / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology*; D003374:Coumarins / Q000378:metabolism / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects*; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008545:Melanoma; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D003374:Coumarins; D003574:Cytochrome c Group; D010446:Peptide Fragments; D012333:RNA, Messenger; C055467:7-amino-4-trifluoromethylcoumarin; D005047:Etoposide; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases; D002945:Cisplatin