Selective synthesis and retention of 66k protein in a human neuroblastoma cell line (NCG) treated with a cytotoxic dosage of delta 12-prostaglandin J2

delta 12-prostaglandin(PG)J2 (7.5 micrograms/ml) significantly inhibited protein synthesis and cell growth in a human neuroblastoma cell line (NCG), decreasing these factors by 31.5% and 78.2% of the control values, respectively. Two protein synthesis inhibitors, cycloheximide (CHM) and emetine, exhibited a dose-dependent protective effect for neuroblastoma cells against delta 12-PGJ2 cytotoxicity. At a concentration of 15 micrograms/ml CHM, the number of viable cells increased from 21.8% to 36.7% of the control value (p less than 0.01). The sodium dodecyl sulfate-polyacrylamide gel analysis of 35S]methionine-incorporated proteins revealed an increased synthesis of 86k, 70k and 66k proteins in the delta 12-PGJ2-treated NCG cells under the condition that delta 12-PGJ2 exerts cytotoxicity. Of these proteins, the amount of 66k protein was particularly increased in cell cytosol; however, its synthesis did not occur when CHM prohibited the delta 12-PGJ2 cytotoxic effect. When emetine was used instead of CHM, similar results were obtained. These results strongly suggest that the 66k protein plays a critical role in the delta 12-PGJ2 cytotoxicity.