Anticlastogenic, antigenotoxic and apoptotic activity of epigallocatechin gallate: a green tea polyphenol
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Published on: July 5, 2017
Madhumita Roy1, Sutapa Chakrabarty, Dona Sinha
1Department of Environmental Carcinogenesis and Toxicology, Chittaranjan National Cancer Institute, 37 SP Mukherjee Road, Kolkata 700 026, India.
Abstract:
Modulation of events characteristic of carcinogenesis or of cancer cells is being emphasized as a rational strategy to control cancer. Green tea polyphenol epigallocatechin gallate (EGCG) has been shown to be highly active as a cancer chemopreventive agent. Certain cellular and molecular events relevant to carcinogenesis are also modified by EGCG. The present investigation was carried out to examine the effects of EGCG on the cytogenetic change and DNA damage induced by toxicant H(2)O(2) and carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Chinese hamster V-79 cells in culture. Cytogenetic change as evident by the formation of micronuclei and DNA damage in the form of comet tail length during single cell gel electrophoresis was found to be significantly suppressed by EGCG in a dose dependent manner. Cells preincubated with EGCG were protected from subsequent damage by the genotoxic agents. Apoptosis, a highly organized physiological mechanism to eliminate injured or abnormal cells, is also implicated in multistage carcinogenesis. Initiated cells, cells at promotional stage or fully transformed cells can be eliminated through apoptosis. It was observed that EGCG suppressed growth and proliferation of K-562 cells derived from human chronic myelogenic leukemia. Morphological features of treated cells and characteristic DNA fragmentation revealed that the cytotoxicity was due to induction of apoptosis. This was mediated by activation of caspase 3 and caspase 8. Results show that EGCG not only protects normal cells against genotoxic hazard but also eliminate cancer cells through induction of apoptosis.
Insights
Epigallocatechin gallate (EGCG) from green tea protects normal cells from DNA damage and carcinogens. EGCG also eliminates human leukemia cells by inducing apoptosis, offering a dual cancer-protective strategy.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Cancer control strategies focus on modulating carcinogenesis and cancer cell behavior.
- Green tea polyphenol epigallocatechin gallate (EGCG) is recognized for its cancer chemopreventive properties.
- EGCG influences cellular and molecular events crucial to carcinogenesis.
Purpose of the Study:
- To investigate the effects of EGCG on cytogenetic damage and DNA damage induced by hydrogen peroxide (H2O2) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).
- To evaluate EGCG's role in inducing apoptosis in cancer cells, specifically human chronic myelogenic leukemia K-562 cells.
Main Methods:
- Chinese hamster V-79 cells were exposed to H2O2 and MNNG, with and without EGCG pre-incubation.
- Cytogenetic damage assessed via micronucleus formation.
- DNA damage evaluated using single-cell gel electrophoresis (comet assay).
- K-562 cell proliferation and apoptosis induction were analyzed morphologically and biochemically (DNA fragmentation, caspase activation).
Main Results:
- EGCG significantly suppressed MNNG- and H2O2-induced cytogenetic damage and DNA damage in a dose-dependent manner.
- Pre-incubation with EGCG protected V-79 cells from genotoxic agent-induced damage.
- EGCG inhibited growth and proliferation of K-562 leukemia cells.
- EGCG induced apoptosis in K-562 cells, evidenced by morphological changes and DNA fragmentation, mediated by caspase 3 and caspase 8 activation.
Conclusions:
- EGCG demonstrates a dual role in cancer prevention and therapy.
- It protects normal cells against genotoxic damage, thereby acting as a chemopreventive agent.
- EGCG effectively eliminates cancer cells, such as leukemia cells, through the induction of apoptosis, suggesting therapeutic potential.