The CTP: Phosphocholine cytidylyltransferase inhibitor 1-o-octadecyl-2-methyl-rac-glycero-3-phosphocholine induces apoptosis in cwsv1 hepatocytes

Choline deficiency (CD) causes apoptotic cell death in rat hepatocytes. The role of the CDP-choline pathway for phosphatidylcholine synthesis in the response of S V40 immortalized, p53 inactivated, CWSV-1 rat hepatocytes to CD in vitro was investigated. CWSV-1 hepatocytes were plated in choline sufficient (CS) (70 |aM) serum-free medium for 4 days, then treated with l-O-octadecyl-2-methylrac-glycero-3-phosphocholine (18-GPC) (40-50 nM for 6 hours), an inhibitor of CTP: phosphocholine cytidylyltransferase. 18-GPC treated cells had more DNA strand breaks (TUNEL method), exhibited classical morphological features of apoptosis, and detached from the plate at higher rates than controls. Internucleosomal DNA cleavage was assessed using agarose gel electrophoresis. Flow cytometry after bromodeoxyuridine/ propidium iodide labeling were used to measure the effects of 18-GPC on the cell cycle. CS cells progressed through the cell cycle. 18-GPC treated cells showed a decrease in the number of cells in S phase (5 percent vs 24 percent) and an increase of cells in G2 phase (12 percent vs 4 percent) compared to CS cells. These data suggest that pharmacologie inhibition of CTP: phosphocholine cytidylyltransferase induces cell cycle arrest and apoptosis via p53 independent pathway.