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Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue
Published on: March 23, 2015
Release of cytochrome c from isolated mitochondria by etoposide
Jung-Hee Park1, Tae-Hyoung Kim
1Department of Biochemistry, Chosun University School of Medicine, Dong-Gu, Gwangju, Korea.
Abstract:
The efficacy of chemotherapeutic agents on tumor cells has been shown to be modulated by tumor suppressor gene p53 and its target genes such as Bcl-2 family members (Bax, Noxa, and PUMA). However, various chemotherapeutic agents can induce cell death in tumor cells that do not express the functional p53, suggesting that some chemotherapeutic agents may induce cell death in a p53-independent pathway. Here we showed that etoposide can induce the similar degree of cell death in p53-deficient HCT 116 cells, whereas 5'-FU-mediated cell death is strongly dependent on the existence of functional p53 in HCT 116 cells. Further, we provide the evidence that etoposide can induce the cytochrome c release from isolated mitochondria, and etoposide-induced cytochrome c release is not accompanied with the large amplitude swelling of mitochondria. These data suggest that etoposide can directly induce the mitochondrial dysfunction irrespective of p53 status, and it may, at least in part, account for the p53-independent pathway in cell death induced by chemotherapeutic agents.
Insights
Etoposide induces tumor cell death independently of the p53 tumor suppressor gene. This occurs through direct mitochondrial dysfunction, offering a p53-independent pathway for chemotherapy.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- The tumor suppressor gene p53 and its targets regulate chemotherapy efficacy.
- Some chemotherapeutic agents induce cell death in p53-deficient tumor cells, suggesting p53-independent pathways.
- Understanding these pathways is crucial for developing effective cancer treatments.
Purpose of the Study:
- To investigate the role of p53 in etoposide- and 5'-FU-induced cell death.
- To elucidate the mechanism of p53-independent cell death induced by etoposide.
Main Methods:
- Comparison of etoposide and 5'-FU efficacy in p53-deficient HCT 116 cells.
- Analysis of cytochrome c release from isolated mitochondria upon etoposide treatment.
- Assessment of mitochondrial swelling in response to etoposide.
Main Results:
- Etoposide induced significant cell death in p53-deficient cells, similar to p53-expressing cells.
- 5'-FU-mediated cell death was highly dependent on functional p53.
- Etoposide triggered cytochrome c release from mitochondria without causing swelling, indicating direct mitochondrial dysfunction.
- This mitochondrial dysfunction occurred irrespective of p53 status.
Conclusions:
- Etoposide induces cell death through a p53-independent pathway involving direct mitochondrial dysfunction.
- This mechanism may explain how certain chemotherapeutic agents overcome p53 deficiency in tumors.
- Targeting mitochondrial pathways could be a strategy for treating p53-deficient cancers.
