Role of antioxidant enzymes in the induction of increased experimental metastasis by hydroxyurea.
BACKGROUND
Treatment of tumor cells with hydroxyurea and other DNA-damaging agents has been shown to increase the experimental metastatic potential of these cells.


OBJECTIVE
We sought to elucidate some of the biochemical and genetic changes that promote tumor cell metastasis in hydroxyurea-treated cells. We hypothesized that drug treatment induces resistance to oxidative damage and that elimination of this resistance reverses the drug-induced experimental metastatic capabilities of tumor cells.


METHODS
We examined the effect of hydroxyurea treatment on B16 melanoma cells with respect to experimental metastatic potential, resistance to hydrogen peroxide (H2O2), glutathione peroxidase activity and messenger RNA (mRNA) level, glutathione reductase activity, glutathione levels, glutathione-S-transferase activity, and catalase activity and mRNA level.


RESULTS
Hydroxyurea-treated cells were transiently more metastatic following intravenous injection in syngeneic mice and transiently more resistant than untreated cells to exogenous H2O2. Hydroxyurea-induced experimental metastases and H2O2 resistance were eliminated by depletion of intracellular glutathione with buthionine sulfoximine. Glutathione peroxidase activity and mRNA level, glutathione reductase activity, and reduced glutathione levels were all transiently increased in hydroxyurea-treated cells, whereas the increase in glutathione-S-transferase activity was sustained. Catalase activity was modestly increased with no increase in its mRNA levels.


CONCLUSIONS
In B16 melanoma cells, experimental metastasis induced by hydroxyurea appears to depend on a process that requires glutathione. Hydroxyurea treatment also induces resistance to exogenous H2O2, which may be due to induction of glutathione and antioxidant enzyme activity.


CONCLUSIONS
The role of antioxidants in B16 melanoma cells offers new insights into the metastatic process and the cellular response to chemotherapy.
Eskenazi
A E
AE
Department of Pediatrics, University of Maryland School of Medicine, Baltimore.
Pinkas
J
J
Whitin
J C
JC
Arguello
F
F
Cohen
H J
HJ
Frantz
C N
CN
D000818:Animals; D019328:Buthionine Sulfoximine; D002374:Catalase / Q000378:metabolism; D005260:Female; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D006918:Hydroxyurea / Q000494:pharmacology*; D008546:Melanoma, Experimental / Q000473:pathology*; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009362:Neoplasm Metastasis; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000378:metabolism
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D005982:Glutathione Transferase; D005978:Glutathione; D006918:Hydroxyurea