Microtubule disruption enhances prostaglandin E₂ production in osteoblastic cells

Prostaglandins have been implicated in the response of bone to mechanical stimuli. To explore the potential role of the cytoskeleton in the control of prostaglandin production, we examined the effect of cytoskeleton disrupting agents on arachidonic acid metabolism in rat calvaria osteoblastic cells. We found that microtubule disrupting agents increase prostaglandin E production 4-5-fold. Stimulation was first detectable at 4 h and rose sharply between 4 and 8 h. 2 h exposure to 1 μM colchicine was sufficient to produce the maximum effect. Cytochalasin B at concentrations which caused marked shape changes had no effect on prostaglandin E production or on its stimulation by colchicine. Taxol, a stabilizer of microtubules, reduced the colchicine effect. The increase in prostaglandin E production was associated with enhanced conversion of arachidonic acid to prostaglandin E₂ rather than enhanced release of arachidonic acid from phospholipids. This increase in enzymatic activity was not abolished by cycloheximide treatment at concentrations which inhibited 90% of protein synthesis in the cells.