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IN THE ABSENCE OF EPSTEIN‐BARR VIRUS INFECTION, PHORBOL ESTER MODULATES APOPTOSIS IN CYCLOHEXIMIDE‐TREATED BURKITT'S LYMPHOMA (BJA‐B) CELLS
Author(s) -
Ishii Hideaki,
Tamauchi Hidekazu,
Gobé Glenda C.
Publication year - 1997
Publication title -
international journal of experimental pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.671
H-Index - 72
eISSN - 1365-2613
pISSN - 0959-9673
DOI - 10.1046/j.1365-2613.1997.170350.x
Subject(s) - apoptosis , cycloheximide , phorbol , flow cytometry , microbiology and biotechnology , biology , programmed cell death , protein kinase c , chemistry , signal transduction , biochemistry , protein biosynthesis
We have shown previously that cycloheximide (CHX), a potent protein synthesis inhibitor, induces high levels of apoptosis in Epstein‐Barr virus free (EBV(−)) Burkitt’s lymphoma (BJA‐B) cells, with comparably reduced levels of apoptosis in the EBV positive (EBV(+)) cells. Modulation of CHX‐induced apoptosis in EBV(−) and (+) B cells is reported here using concurrent treatment with phorbol ester (phorbol 12,13‐dibutyrate, PdBu). Cells were collected at 0, 3, 6, 12, 24 and 48 hours after treatment with (i) 1 μg/ml CHX, (ii) 0.1 μg/ml PdBu (1 hour pretreatment before 0 h), or (iii) CHX + PdBu (CHX added at 0 h, 1 hour after PdBu). Control cultures were untreated. Apoptotic, necrotic or viable cells were quantified using histological, ultrastructural and biochemical parameters. Protein synthesis was assessed using 35 S‐methionine incorporation. Intracellular calcium concentrations were measured using flow cytometry. PdBu alone had little effect on cell death. High levels of CHX‐induced apoptosis in EBV(−) cells were significantly reduced by concurrent addition of PdBu ( P < 0.005). In contrast, low levels of CHX‐induced apoptosis in EBV(+) cells were not significantly altered by PdBu treatment. In EBV(−) cells, a negative relationship was observed between levels of apoptosis and calcium concentrations, whereas in EBV(+) cells, there was negligible correlation between these parameters. Thus high levels of CHX‐induced apoptosis in EBV(−) cells occur via a PKC‐dependent pathway, whereas CHX treatment of EBV(+) cells induces comparatively low levels of apoptosis that occur via a PKC‐independent mechanism. The results application in the therapeutic intervention for cancers developing in association with EBV infection.