C-13-NMR investigation of protein synthesis during apoptosis in human leukemic cell lines

In order to evaluate the role of protein synthesis in apoptosis, C-13-NMR h as been used to study the levels of protein synthesis in three different hu man leukemic cell lines in the presence and absence of dexamethasone-induce d apoptosis. Measurements were done on one dexamethasone-sensitive (CEM-C7- 14) and two different dexamethasone-resistant variants (CEM-4R4 and CEM-ICR 27-4). The incorporation of C-13-labeled amino acids into cellular proteins , which reflects the level of new protein synthesis, was monitored by C-13- NMR spectroscopy. In the absence of dexamethasone, the level of protein syn thesis was found to be significantly different among the three cell lines. Dexamethasone caused a significant reduction (congruent to 60-87%) in the l evel of protein synthesis in dexamethasone-sensitive CEM-C7-14 cells, while having no significant effect on protein synthesis in dexamethasone-resista nt CEM-4R4 cells. Dexamethasone treatment caused a significant enhancement of the level of protein synthesis in the CEM-ICR27-4 cells. Synthesis of pr oteins was found to occur during apoptosis, albeit at a low level, suggesti ng a role for the synthesis of specific proteins in the mechanism of apopto sis. J. Cell. Physiol. 181:147-152, 1999. (C) 1999 Wiley-Liss, Inc.