High-dose pyridoxal supplemented culture medium inhibits the growth of a human malignant melanoma cell line.

Abstract

The in vitro growth characteristics of a human malignant melanoma cell line cultured in 0.5 mM pyridoxal supplemented medium were studied. Experimentation revealed that the high-dose pyridoxal supplemented medium severely inhibited the growth of melanoma cells over a 72-hour growth period. Additional experimentation showed that cells cultured for 6 hours in the pyridoxal supplemented medium took up 25% less and incorporated 20% less [3H]uridine than control cultures. [3H]Glucose uptake was reduced by 23% at this time point. [3H]Thymidine uptake was inhibited by 12%, but no inhibition was detected in [3H]thymidine incorporation. When the vitamin B6 antagonist 4-deoxypyridoxine (which competes with pyridoxal for pyridoxal kinase) was added to the pyridoxal supplemented medium, the inhibition in [3H]uridine incorporation was reduced from 19% to 6%. However, 4-deoxypyridoxine did not reverse the inhibition of [3H]uridine uptake. These results indicate that pyridoxal and its metabolite, pyridoxal 5'-phosphate, may be involved in the growth regulation of a human malignant melanoma cell line.