Alteration of Oleate-Phospholipase D Activities in Some Cell Lines after Irradiation

Kim, Chul Yong; Choi, Myung Un; Choi, Myung Sun

Abstract

PURPOSE: Phospholipase D (PLD) catalyzes the hydrolytic cleavage of terminal phosphate diester bond of glycerophopholipids to produce phosphatidic acid (PA). PLD plays an important role in signal transduction and is known to be involved closely in cancer promotion, inflammation, and other cell responses. In order to evaluate radiation effect in tumor cells, various cells were screened for PLD activities and examined their radiation effects on PLD following gamma- ray irradiation.
MATERIALS AND METHODS
PLD activities in 19 species of cell were measured by radioactive isotope method with 1,2 - di [1-14C] phosphatidylcholine in the presence of oleate. Among the cell lines examined, VERO 76, L 1210 and P 388 were selected and examined for their effects of metal ions and agonists on PLD activities before and after irradiation by Co-60 teletheraphy unit.
RESULTS
The activities of oleate-PLD were observed in 11 species among 19 cell lines examined. VERO 76 and L 1210 cells showed that the PLD activity increased immediately after irradiation and reached to 150~200% of the control levels. The activation of PLD in response to gamma-ray was maximum at 20 Gy. In irradiated VERO 76, the stimulatory effect of Mg2+ was reduced and the activation of PLD by agonists in irradiated cells vary from those of the control cells.
CONCLUSION
The activation effect of irradiation on PLD activity observed strongly implies that the PLD activity is closely related to the phenomena of cell necrosis. Therefore the cell lines examined here could provide a good source for the study of radiobiology that cover from cell death to cancer promotion.