Relationship Between Glucosamine Uptake and Alkaline Phosphatase in HeLa Cells: Effects of Glucose and Prednisolone

Summary

The uptake and incorporation of D-1-¹⁴C-glucosamine and D-1-¹⁴C-glucose were studied in 2 strains of HeLa cells. The strains varied in their response to the presence of glucocorticoids in the culture medium. Strain S3G had a constitutively low alkaline phosphatase which became elevated by these steroids. In strain S3K, the high basal level of this enzyme was markedly suppressed. In both strains, the uptake of glucosamine was highest during the period of cell attachment and early growth but was not affected by the relative cell density of the culture. Glucosamine (1 mM), when present in the medium, prevented the increase of alkaline phosphatase, regardless of whether it was induced by prednisolone, as in the S3G strain, or whether it occurred during preconfluent growth, as in the S3K strain. In addition to its effect on alkaline phosphatase, glucosamine reduced the uptake of glucose by the cells. This effect was reversed by high concentration of glucose in the medium, pointing to the competition between the 2 carbohydrates and to an effect of glucocorticoids on the initial steps of carbohydrate utilization.