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An association between mitochondrial function and all‐ trans retinoic acid‐induced apoptosis in acute myeloblastic leukaemia cells
Author(s) -
Zheng Aiping,
Mäntymaa Pentti,
Säily Marjaana,
Siitonen Timo,
Savolainen EevaRiitta,
Koistinen Pirjo
Publication year - 1999
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1999.01303.x
Subject(s) - apoptosis , flow cytometry , microbiology and biotechnology , retinoic acid , mitochondrion , cell culture , biology , programmed cell death , poly adp ribose polymerase , annexin , chemistry , biochemistry , dna , genetics , polymerase
The present study investigated whether all‐ trans retinoic acid (ATRA)‐induced apoptosis in acute myeloblastic leukaemia (AML) is related to changes in mitochondrial function. Two human AML cell lines, OU‐AML‐3 and OU‐AML‐7, known to be inducible to time‐dependent apoptosis of varying degrees by ATRA, were used. Apoptosis induced by ATRA was shown to be a slow event. It was detected by the DNA electrophoretic method and cytofluorimetrical annexin V assay after 48 h exposure, and by morphology and polyADPribose polymerase (PARP) cleavage after 72 h exposure of AML cells to ATRA. The efflux of mitochondrial cytochrome c to cytosol was notable in Western blotting after 48 h exposure of the cells to ATRA and was observed before the drop in the mitochondrial membrane potential, which only took place after 72 h exposure, when measured by flow cytometry and a JC‐1 probe. The apoptotic events in mitochondria were more evident in the OU‐AML‐3 than the OU‐AML‐7 cell line. This might relate to the different bcl‐2 contents of the cell lines: the basic bcl‐2 levels of the OU‐AML‐7 cell line were almost twofold compared to that of the OU‐AML‐3 cell line, as analysed by the ELISA method. However, both of the cell lines showed progressive down‐regulation of bcl‐2, which began after 12–24 h exposure of the cells to ATRA as determined by ELISA, Western blotting and flow cytometry. The present results show that mitochondria have a role in ATRA‐induced apoptosis in AML cells and down‐regulation of bcl‐2 is related to it. In view of the previously published studies, the present results underline the fact that the timing of apoptotic events, such as fragmentation of DNA, externalization of phosphatidylserine, cytochrome c efflux, change in mitochondrial membrane potential and cleavage of PARP, are, to a notable extent, cell type and inducer‐dependent.