Arachidonic acid stimulates cell growth in an osteoblastic cell line, MC3T3-E1, by noneicosanoid mechanism.

Arachidonic acid, added to alpha-minimum essential medium containing 10% fetal bovine serum at the final concentration of 10(-4) M, significantly increased DNA content of an osteoblastic cell line, MC3T3-E1, along with an increase of DNA synthesis. No growth-stimulatory effect of arachidonic acid was observed under serum-free condition. alpha-Linolenic acid, which cannot be converted to arachidonic acid, also increased DNA content at 10(-4) M. Additionally, the stimulatory effects of these fatty acids were not inhibited by simultaneous addition of 10(-5) M of indomethacin. Indomethacin, when added to alpha-minimum essential medium with 10% fetal bovine serum, also significantly increased DNA content of MC3T3-E1 cells. These results suggest that arachidonic acid may potentiate the growth-stimulatory effect of serum-derived growth factors probably via noneicosanoid mechanism. Rat osteogenic sarcoma cell line, UMR106, also showed an increase in DNA content with arachidonic acid treatment. Hence, it is suggested that arachidonic acid may stimulate proliferation of cells of osteoblastic lineage. It is also suggested that indomethacin, probably by blocking endogenous prostaglandin E2 synthesis, stimulates cell growth in MC3T3-E1 cells.