Oligonucleosomal DNA fragmentation in MCF-7 cells undergoing palmitate-induced apoptosis

• Published in: Biochemistry (Moscow) Vol. 68; no. 12; pp. 1335 - 1341
• Main Authors: Semenov, D V, Aronov, P A, Kuligina, E V, Potapenko, M O, Richter, V A
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01.12.2003
• Subjects: Apoptosis; Apoptosis - drug effects; Caspase 3; Caspases - genetics; Cell Line, Tumor; Cells; Deoxyribonucleases - metabolism; Deoxyribonucleic acid; DNA; DNA Fragmentation - drug effects; DNA, Neoplasm - metabolism; Exons - genetics; Humans; Microscopy, Fluorescence; Nucleosomes - chemistry; Nucleosomes - drug effects; Nucleosomes - metabolism; Palmitates - pharmacology; Placenta - cytology; Placenta - drug effects; Placenta - metabolism; Sequence Deletion - genetics; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0006-2979; 1608-3040
• DOI: 10.1023/B:BIRY.0000011655.58235.44

Oligonucleosomal fragmentation of nuclear DNA is the late-stage apoptosis hallmark. In apoptotic mammalian cells the fragmentation is catalyzed by DFF40/CAD DNase primarily activated by caspase 3 through the site-specific proteolytic cleavage of DFF45/ICAD. A deletion in the casp3 gene of human breast adenocarcinoma MCF-7 results in lack of procaspase 3 in these cells. The absence of caspase 3 in MCF-7 leads to disability to activate oligonucleosomal DNA fragmentation in TNF-alpha induced cell death. In this study, sodium palmitate was used as an apoptotic stimulus for MCF-7. It has been shown that palmitate but not TNF-alpha induces both apoptotic changes in nuclei and oligonucleosomal DNA fragmentation in casp3-mutated MCF-7. Activation and accumulation of 40-50 kD DFF40-like DNases in nuclei of palmitate-treated apoptotic MCF-7 were detected by SDS-DNA-PAGE assay. Microsomal fraction of apoptotic MCF-7 does not contain any detectable DNases, but activates 40-50 kD nucleases when incubated with human placental chromatin. Furthermore, microsomes of apoptotic MCF-7 induce oligonucleosomal fragmentation of chromatin in a cell-free system. Both the activation of DNases and chromatin fragmentation are suppressed in the presence of the caspase 3/7 inhibitor Ac-DEVD-CHO. Microsome-associated caspase 7 is suggested to play an essential role in the induction of oligonucleosomal DNA fragmentation in casp3-deficient MCF-7 cells.