Modulation of vindesine and doxorubicin resistance in multidrug-resistant pleural mesothelioma cells by tumor necrosis factor-alpha.
Tumor necrosis factor-alpha (TNF-alpha) has been shown to enhance the cytotoxicity of a variety of antineoplastic agents. To examine whether multidrug-resistant cells are targets of TNF-alpha, and whether TNF-alpha is capable of modulating chemoresistance of these cells, a pleural mesothelioma cell line (PXF1118L) and two multidrug-resistant sublines thereof were used as experimental models. Drug resistance of these cells was due to P-glycoprotein expression, as confirmed by (1) staining with a monoclonal antibody (MRK16) specific for human P-glycoprotein, (2) decreased accumulation of [3H]vinblastine that was reversed by verapamil, and (3) enhanced cytotoxicity of vindesine in the presence of verapamil. Parental and multidrug-resistant cells exhibited little but comparable sensitivity to TNF-alpha alone. Combining TNF-alpha with vindesine or, to a lesser extent, with doxorubicin, but not with cisplatin, resulted in greater cytotoxicity towards multidrug-resistant cells than seen for each compound alone, indicating a synergism. In contrast, TNF-alpha failed to modulate vindesine or doxorubicin cytotoxicity in parental cells. [3H]Vinblastine accumulation was unaffected by TNF-alpha, and chemoresistance was reduced by TNF-alpha also in the presence of verapamil (10 microM), indicating that TNF-alpha was acting in a way different from calcium-channel blockers. Though the molecular mechanism by which TNF-alpha was enhancing vindesine and doxorubicin cytotoxicity remained undefined in this study, the numbers of TNF-alpha binding sites on parental and on multidrug-resistant cells were similar, and P-glycoprotein expression was unmodulated during the entire 48 h incubation period. In conclusion, we show that TNF-alpha increases the cytotoxicity of anticancer drugs in multidrug-resistant tumor cells by a mechanism that differs from most chemosensitizing agents, including verapamil. Further studies will be needed to clarify the mechanism by which TNF-alpha synergizes with anticancer drugs.
Licht
T
T
University of Freiburg, Department of Internal Medicine 1 (Hematology/Oncology), Germany.
Lübbert
M
M
Martens
C
C
Bross
K J
KJ
Fiebig
H H
HH
Mertelsmann
R
R
Herrmann
F
F
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000493:pharmacokinetics / Q000633:toxicity*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008654:Mesothelioma; D010997:Pleural Neoplasms; D011994:Recombinant Proteins / Q000494:pharmacology; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology; D014751:Vindesine / Q000493:pharmacokinetics / Q000633:toxicity*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D004317:Doxorubicin; D014700:Verapamil; D014751:Vindesine