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Free radicals: biology and relevance to disease
1Department of Medicine, Nizam's Institute of Medical Sciences, Hyderabad.
Abstract:
Free radicals are the major mediators of the bactericidal and cytotoxic actions of polymorphonuclear leucocytes, macrophages and monocytes, and can stimulate lymphocytes mitogenically. Hydrogen peroxide induces interferon production by human macrophages and activates NK (natural killer) cells; interferon can in turn enhance free radical generation in the cells. Anti-cancer drugs such as doxorubicin, vincristine and adriamycin; radiation; and haematoporphyrin derivative-induced photosensitization all can augment free radical generation and thus, cause tumour cell lysis. Our recent studies suggest that some polyunsaturated fatty acids such as gamma-linolenic acid, arachidonic acid and eicosapentaenoic acid can selectively kill tumour cells but not normal cells in vitro by virtue of their capacity to augment free radical generation in the tumour cells. Thus, free radicals have both harmful and beneficial actions.
Insights
Free radicals, generated by immune cells and certain treatments, can harm or kill cells. Some polyunsaturated fatty acids selectively eliminate tumor cells by increasing free radicals.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Free radicals mediate critical functions of immune cells like macrophages and monocytes.
- Hydrogen peroxide and interferon play roles in immune cell activation and free radical production.
- Various anti-cancer therapies and agents induce free radical generation, leading to tumor cell death.
Purpose of the Study:
- To explore the dual role of free radicals in cellular processes.
- To investigate the potential of polyunsaturated fatty acids (PUFAs) in cancer therapy.
Main Methods:
- Review of existing literature on free radical generation and function.
- In vitro studies examining the effects of specific PUFAs on tumor and normal cells.
Main Results:
- Free radicals are involved in both beneficial immune responses and cytotoxic actions.
- Certain PUFAs (gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid) demonstrated selective tumor cell killing.
- This selective killing by PUFAs is attributed to augmented free radical generation within tumor cells.
Conclusions:
- Free radicals exhibit both detrimental and therapeutic properties.
- Specific PUFAs show promise as selective anti-cancer agents by modulating free radical generation.