Apoptosis in human lymphoblastoid cells induced by acivicin, a specific γ glutamyltransferase inhibitor

We examined the effects of acivicin, a specific inhibitor of the ectoenzyme γ‐glutamyltransferase (γ‐GT), on γGT activity and apoptosis in 2 human T‐lymphoblastoid CEM cell lines, CCRF and VBL‐100. In both cell lines, acivicin was found to cause morphological and biochemical changes of apoptosis in a dose‐ dependent manner. There was a close correlation between inhibition of γ‐GT activity and the emergence of apoptotic cells. However, VBL‐100 cells had a 50% higher γ‐GT basal activity than CCRF‐CEM cells, their enzyme activity was more inhibited, and, they had a greater apoptotic response to acivicin. The γ‐GT‐specific activity in apoptotic/dead cells was also almost totally inhibited, while that of cells that remained alive after 5 days of acivicin treatment was not. These findings confirm that γ‐GT is implicated in the process of apoptosis of CEM cells. © 1995 Wiley‐Liss, Inc.