Effect of nitric oxide on the anticancer activity of the topoisomerase-active drugs etoposide and adriamycin in human melanoma cells.
Nitric oxide (·NO) was originally identified as an innate cytotoxin. However, in tumors it can enhance resistance to chemotherapy and exacerbate cancer progression. Our previous studies indicated that (·NO/·NO-derived species react with etoposide (VP-16) in vitro and form products that show significantly reduced activity toward HL60 cells and lipopolysaccharide (LPS)-induced macrophages. Here, we further confirm the hypothesis that (÷)NO generation contributes to VP-16 resistance by examining interactions of ·NO with VP-16 in inducible nitric-oxide synthase (iNOS)-expressing human melanoma A375 cells. Inhibition of iNOS catalysis by N(6)-(1-iminoethyl)-L-lysine dihydrochloride (L-NIL) in human melanoma A375 cells reversed VP-16 resistance, leading to increased DNA damage and apoptosis. Furthermore, we found that coculturing A375 melanoma cells with LPS-induced macrophage RAW cells also significantly reduced VP-16 cytotoxicity and DNA damage in A375 cells. We also examined the interactions of (·)NO with another topoisomerase active drug, Adriamycin, in A375 cells. In contrast, to VP-16, (·)NO caused no significant modulation of cytotoxicity or Adriamycin-dependent apoptosis, suggesting that (⋅)NO does not interact with Adriamycin. Our studies support the hypothesis that (·)NO oxidative chemistry can detoxify VP-16 through direct nitrogen oxide radical attack. Our results provide insights into the pharmacology and anticancer mechanisms of VP-16 that may ultimately contribute to increased resistance, treatment failure, and induction of secondary leukemia in VP-16-treated patients.
Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina (B.K.S., A.K., S.B., R.P.M.); and National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (M.G.E.).
Birandra K
BK
Sinha
Ashutosh
A
Kumar
Suchandra
S
Bhattacharjee
Michael G
MG
Espey
Ronald P
RP
Mason
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D026942:DNA Topoisomerases / Q000187:drug effects*; D004317:Doxorubicin / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology*; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects; D008545:Melanoma / Q000188:drug therapy*; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors
D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D004791:Enzyme Inhibitors; C090663:N(6)-(1-iminoethyl)lysine; D009569:Nitric Oxide; D005047:Etoposide; D004317:Doxorubicin; D019001:Nitric Oxide Synthase; D053148:Caspase 3; D026942:DNA Topoisomerases; D008239:Lysine