Importance of cytochrome c redox state for ceramide-induced apoptosis of human mammary adenocarcinoma cells.
BACKGROUND
Ceramides are intracellular lipid mediator implicated in various cellular responses, including oxidative stress and programmed cell death. Studies demonstrated strong links between ceramide and the mitochondria in the regulation of apoptosis. However, the mechanism of apoptosis induced by ceramides is not fully understood. The present study delineates importance of the redox state of cytochrome c for release of cytochrome c and apoptosis of human mammary adenocarcinoma MCF-7 and MDA-MB-231 cells induced by ceramides.


METHODS
The study uses MCF-7 and MDA-MB-231 cells, isolated mitochondria, submitochondrial particles, and oxidized and reduced cytochrome c. Methods used include flow cytometry, immunoblotting, spectroscopy, and respirometry.


RESULTS
We show that ceramides induce mitochondrial oxidative stress and release of cytochrome c from the mitochondria of these cells. Our findings show that ceramides react with oxidized cytochrome c whereas reduced cytochrome c does not react with ceramides. We also show that oxidized cytochrome c reacted with ceramides exerts lower reducibility and function to support mitochondrial respiration. Furthermore, our data show that glutathione protects cytochrome c of reacting with ceramides by increasing the reduced state of cytochrome c.


CONCLUSIONS
Ceramides induce oxidative stress and apoptosis in human mammary adenocarcinoma cells by interacting with oxidized cytochrome c leading to the release of cytochrome c from the mitochondria. Our findings suggest a novel mechanism for protective role of glutathione.


CONCLUSIONS
Our study suggests that the redox state of cytochrome c is important in oxidative stress and apoptosis induced by ceramides.
Parihar
Arti
A
Department of Biological Sciences, GDC College, Vikram University, Ujjain, MP, India.
Parihar
Mordhwaj S
MS
Nazarewicz
Rafal
R
Ghafourifar
Pedram
P
D000230:Adenocarcinoma / Q000473:pathology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001943:Breast Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D002518:Ceramides / Q000494:pharmacology*; D045304:Cytochromes c / Q000187:drug effects / Q000378:metabolism*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000502:physiology; D010084:Oxidation-Reduction
D002518:Ceramides; D045304:Cytochromes c; D005978:Glutathione