The effect of ascorbic acid on arachidonic acid and prostaglandin E 2 metabolism in B16 murine melanoma cells

Abstract

Ascorbic acid (Asc), arachidonic acid (AA) and prostaglandin E 2 (PGE 2) are reported to be important in maintaining the stability of the cell matrix. Asc has also been shown to influence fatty acid (FA) and PGE 2 synthesis, with the result that effects of Asc on cell growth are suggested to be mediated through the metabolism of these two compounds. This study examined the effect of Asc, supplemented over the concentration range of 0–100 μg/ml, on the in vitro cell growth of non-malignant LLCMK (monkey kidney) cells and malignant B16 murine melanoma cells. The effects of Asc supplementation on AA and PGE 2 levels in the cell stroma and membrane fractions of the two cell types was also determined. Asc had no significant inhibitory or stimulatory effect on the growth of either the B16 or LLCMK cells. The total percentage AA composition determined in the B16 control cells (combined stroma and membrane fractions), was similar to that determined in the LLCMK control cells. Asc supplementation of the B16 cells, resulted in an inverse relationship between B16 cell growth and total percentage AA composition. PGE 2 concentration in the control B16 cells (combined stroma and membrane fractions) was significantly higher than that detected in the control LLCMK cells. No PGE 2 was detected in the B16 stroma fraction, with all appearing to be located in the membrane fraction. However, upon the supplementation of the B16 cells with increasing Asc concentrations, PGE 2 appeared to be mobilized from the membrane fraction, resulting in increasing PGE 2 levels in the stroma fraction relative to the membrane fraction. This was accompanied by a significant decrease in PGE 2 concentration, in the membrane fraction. B16 cell growth and total (stroma and membrane fractions) PGE 2 concentration in these cells was inversely related, when cultures were supplemented with increasing levels of Asc. Asc supplementation of the LLCMK cells did not appear to have any significant effect on AA or PGE 2 metabolism in these cells.