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.

The Effect ofO6-Alkylguanine-DNA Alkyltransferase and Mismatch Repair Activities on the Sensitivity of Human Melanoma Cells to Temozolomide, 1,3-bis(2-Chloroethyl)1-nitrosourea, and Cisplatin

“…Chemoresistance observed in vivo is reflected in vitro by low chemosensitivity of melanoma cell lines (Schadendorf et al, 1994), suggesting the presence of intrinsic cellular resistance mechanisms. Some of these might involve inhibition or dysregulation of apoptosis (for review, see Serrone and Hersey, 1999;Helmbach et al, 2001Helmbach et al, , 2002,whereas others might be linked to the levels of DNA repair enzymes that either attenuate or potentiate the effect of the drugs.…”

Combined Effect of Proteasome and Calpain Inhibition on Cisplatin-Resistant Human Melanoma Cells

“…Interestingly, the cisplatinresistant MeWo cis1 cells studied here exhibit increased calpain activity even in the absence of cisplatin and already the inhibition of calpain activity is able to induce apoptosis. This latter result may be explained in part by the recently described apoptotic defects in MeWo cis1 cells (11) and by a shift in the NF-nB signaling pathway toward an ubiquitin-proteasome system independent InBa degradation. Calpain-and proteasome-dependent NF-nB activation following TNF treatment has also been observed in human HepG2 cells (8).…”

“…Cell culture. MeWo and MeWo cis1 cells were cultured in RPMI 1640 (Biochrom, Berlin, Germany) supplemented with 10% FCS, penicillin (100 units/mL), and streptomycin (100 Ag/mL) as described (11). MeWo cis1 cells were cultured with additional cisplatin at 1 Ag/mL.…”

Evaluation of Apoptotic Signals in Human Cancer Malignant Melanoma Me45 and Ovarian Carcinoma SKOV3 Cell Death after Chemotherapeutic Reaction with Cisplatin

“…Other studies showed that modulation of apoptotic pathways in human melanoma MeWo cells is drug dependent and highly associated with the drug-resistant phenotype [26] .…”