Effects of Epigallocatechin-3-Gallate (EGCG) on Cell Cycle Distribution and DNA Integrity of K562 Cells, A Human Chronic Myeloid Leukemia (original) (raw)

Protective action of EGCG against anticancer drugs MMS and CP

Internet Journal of Pharmacology

Keywords chromosomal aberration, cyclophosphamide, epigallocatechin gallate egcg, methyl methanesulphonate, sister chromatid exchange sce Citation T Beg, Y Siddique, G Ara, J Gupta, M Afzal. Protective action of EGCG against anticancer drugs MMS and CP. Abstract This experiment was conducted in order to assess the antigenotoxicity potential of Epigallocatechin-3-gallate (EGCG), a catechin, against genotoxicity induced by anticancer drugs, Methyl methanesulphonate (MMS) and cyclophosphamide (CP), in the form of chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs). These drugs were used at 60 M and 0.16 g/ml respectively along with EGCG at 10, 20, and 30 M in cultured human lymphocyte chromosomes. EGCG significantly reduced the The Internet Journal of Pharm acology Navigate... 7/7/2014 Internet Scientific Publications http://ispub.com/IJPHARM/6/2/9606 2/11

Cell Cycle Dysregulation by Green Tea Polyphenol Epigallocatechin-3-Gallate

Biochemical and Biophysical Research Communications, 2000

Epidemiological, in vitro cell culture, and in vivo animal studies have shown that green tea or its constituent polyphenols, particularly its major polyphenol epigallocatechin-3-gallate (EGCG) may protect against many cancer types. In earlier studies, we showed that green tea polyphenol EGCG causes a G0/ G1-phase cell cycle arrest and apoptosis of human epidermoid carcinoma (A431) cells. We also demonstrated that these effects of EGCG may be mediated through the inhibition of nuclear factor kappa B that has been associated with cell cycle regulation and cancer. In this study, employing A431 cells, we provide evidence for the involvement of cyclin kinase inhibitor (cki)cyclin-cyclin-dependent kinase (cdk) machinery during cell cycle deregulation by EGCG. As shown by immunoblot analysis, EGCG treatment of the cells resulted in significant dose-and time-dependent (i) upregulation of the protein expression of WAF1/p21, KIP1/p27, p16 and p18, (ii) downmodulation of the protein expression of cyclin D1, cdk4 and cdk6, but not of cyclin E and cdk2, (iii) inhibition of the kinase activities associated with cyclin E, cyclin D1, cdk2, cdk4 and cdk6. Taken together, our study suggests that EGCG causes an induction of G1-phase ckis, which inhibit the cyclin-cdk complexes operative in G0/G1 phase of the cell cycle thereby causing a G0/G1-phase arrest of the cell cycle, which is an irreversible process ultimately resulting in an apoptotic cell death. We suggest that the naturally occurring agents such as green tea polyphenols which may inhibit cell cycle progression could be developed as potent anticancer agents for the management of cancer.

Epigallocatechin-3-gallate induces apoptosis and cell cycle arrest in HTLV-1-positive and -negative leukemia cells

Medical Oncology, 2007

Epigallocatechin-3-gallate (EGCG) has been shown to have anticarcinogenic effects in in vitro and in vivo models, and this effect is mediated at least in part by its ability to induce apoptosis in cancer cells without affecting normal cells. It has been recognized that estrogen receptor (ER)dependent breast cancers generally have a better prognosis and are often responsive to antiestrogen therapy; however, ER-independent breast cancers are more aggressive and unresponsive to antiestrogens. Using the MDA-MB-468 human breast cancer cell line as an in vitro model of ER-negative breast cancers, we found that treatment of EGCG resulted in dose-dependent (5-80 Ag/mL) and timedependent (24-72 hours) inhibition of cellular proliferation (15-100%) and cell viability (3-78%) in MDA-MB-468 cells. Decrease in cell viability was associated with the induction of apoptosis (18-66%) which was analyzed by DNA ladder assay, fluorescence staining, and flow cytometry. Induction of apoptosis by EGCG could be corroborated to the increased expression of tumor suppressor protein p53 and its phosphorylation at Ser 15 residue. EGCG decreased the expression of antiapoptotic protein Bcl-2 but increased proapoptotic protein Bax in these cells. The increased ratio of Bax/Bcl-2 proteins after EGCG treatment may have resulted in increased release of cytochrome c from mitochondria into cytosols, increased expression of Apaf-1, and activation of caspase-3 and poly(ADP-ribose) polymerase, which may lead to apoptosis in MDA-MB-468 cells. Together, the results of this study provide evidence that EGCG possesses anticarcinogenic effect against ER-negative breast cancer cells and thus provide the molecular basis for the future development of EGCG as a novel and pharmacologically safe chemopreventive agent for breast cancer prevention. [Mol Cancer Ther 2005;4(1):81-90]

Anti-cancer effect of EGCG and its mechanisms

Epidemiological analysis demonstrated there are negative correlation between green tea consumption and the risk of non-Hodgkin lymphoma1 and prostate cancer. Recent studies show (–)-epigallocatechin-3-O-gallate (EGCG), major green tea polyphenol suppresses the proliferation of cancer cells and induces cell death without adversely affecting normal cells. Several molecular mechanisms of its effect have been suggested. Recently, 67-kDa laminin receptor (67LR) was identified as the sensing molecule for EGCG. Surprisingly, 67LR overexpresses in cancer cells play the crucial role in the selective toxicity of EGCG. Moreover, possible downstream mechanisms were suggested in 67LR-dependent the anti-cancer effect of EGCG. This review focused on the molecular mechanism of EGCG and the novel strategy to amplify its effect.

Effects of (−)-epigallocatechin gallate (EGCG) on DNA strand breaks as evaluated by single-cell gel electrophoresis (SCG) in human lymphocytes

Environmental Health and Preventive Medicine, 2001

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol component, is the main ingredient of green tea extract. Although the anti-carcinogenic and cancer inhibitory effects of EGCG have been widely reported, its genotoxicity is not dear and seldom reported. In this study, we examined the effects of EGCG on DNA strand breaks in the isolated lymphocytes and whole blood lymphocytes obtained from two smoking subjects and a nonsmoking healthy subject using a single-cell gel electrophoresis (SCG) assay. The results showed that after 2 hrs of treating the isolated lymphocytes from the smokers, EGCG induced a significant increase in DNA strand breaks at concentrations from 2.5 • 10-s M to 2.0 • 10-4 M, while after 2 hrs of treating the whole blood obtained from the same smokers, EGCG suppressed the DNA strand breaks in the lymphocytes at concentrations of 1.0 • 10-4 M and 2.0 • 10 ~ M. A similar suppressive result was also shown in the whole blood lymphocytes from the nonsmoker at nearly the same concentrations, while at concentrations of 1.0 • 10 .3 M or 2.0)< 10 .3 M, EGCG induced a significant increase in DNA strand breaks in the whole blood lymphocytes from the nonsmoker. This result suggests that EGCG is not only inhibitory against DNA strand breaks in whole blood, but also genotoxic to the isolated or whole blood lymphocytes at high concentrations. Thus, more research is needed to comprehensively assess the effects of EGCG on genetic materials.

Analysis of the Anticancer Potential of Green Tea’s EGCG Component to Inhibit Immortal Cells

Midwestern Journal of Undergraduate Sciences

Green tea has a high abundance of catechins and other antioxidants found organically within its composition. In recent studies, a polyphenolic catechin, referred to as EGCG, has shown the potential to promote advancements in the development of non-harmful cancer treatments. Several experimental questions were explored regarding EGCG, including the concentration of EGCG present in commercial green teas, its anticancer potency, and EGCG’s potential contributions to cell cycle arrest. Briefly, a green tea extract was prepared utilizing ground green tea leaves and a polar extraction method. The fluorescent properties of EGCG were exploited to quantitate its concentration in green tea preparations in comparison to a purified EGCG standard. The anticancer potency of EGCG was then assessed by exposing HeLa (cancer cells) and MRC-5 (primary) cells to green tea extract- containing the EGCG component- for 24 hrs. The cells were evaluated for viability, suggesting that higher concentrations of...

An EGCG derivative effectively induces apoptosis via SHP-1-mediated suppression of BCR-ABL and STAT3 signalling in chronic myelogenous leukaemia

British journal of pharmacology, 2015

EGCG is a component of green tea known to have chemo-preventative effects on several cancers. However, EGCG has limited clinical application, which necessitates the development of a more effective EGCG prodrug as an anticancer agent. In the current study, EGCG derivatives were compared and evaluated for their stability and anti-tumour activity in human CML K562 and KBM5 cells. EGCG-MP showed most prolonged stability compared to other EGCG derivatives. EGCG-MP exerted significant cytotoxicity and increased apoptosis in K562 and KBM5 cells more effectively than the other EGCG derivatives. In addition, EGCG-MP dramatically induced SHP-1 leading to the decrease of BCR-ABL and STAT3 phosphorylation in CML cells, compared to treatment with EGCG. Furthermore, EGCG-MP reduced the phosphorylation of STAT3 and survival genes in K562 cells, compared to treatment with EGCG. Conversely, depletion of SHP-1 or application of the tyrosine phosphatase inhibitor pervanadate blocked the ability of EGC...

Molecular pathway for (−)-epigallocatechin-3-gallate-induced cell cycle arrest and apoptosis of human prostate carcinoma cells

Archives of Biochemistry and Biophysics, 2003

Epigallocatechin-3-gallate (EGCG), the major polyphenolic constituent present in green tea, is a promising chemopreventive agent. We recently showed that green tea polyphenols exert remarkable preventive effects against prostate cancer in a mouse model and many of these effects are mediated by the ability of polyphenols to induce apoptosis in cancer cells [Proc. Natl. Acad. Sci. USA 98 ]. Earlier, we showed that EGCG causes a G0/G1 phase cell cycle arrest and apoptosis of both androgen-sensitive LNCaP and androgen-insensitive DU145 human prostate carcinoma cells, irrespective of p53 status [Toxicol. Appl. Pharmacol. 164 (2000) 82]. Here, we provide molecular understanding of this effect. We tested a hypothesis that EGCG-mediated cell cycle dysregulation and apoptosis is mediated via modulation of cyclin kinase inhibitor (cki)-cyclin-cyclin-dependent kinase (cdk) machinery. As shown by immunoblot analysis, EGCG treatment of LNCaP and DU145 cells resulted in significant dose-and timedependent (i) upregulation of the protein expression of WAF1/p21, KIP1/p27, INK4a/p16, and INK4c/p18, (ii) down-modulation of the protein expression of cyclin D1, cyclin E, cdk2, cdk4, and cdk6, but not of cyclin D2, (iii) increase in the binding of cyclin D1 toward WAF1/p21 and KIP1/p27, and (iv) decrease in the binding of cyclin E toward cdk2. Taken together, our results suggest that EGCG causes an induction of G1 phase ckis, which inhibits the cyclin-cdk complexes operative in the G0/G1 phase of the cell cycle, thereby causing an arrest, which may be an irreversible process ultimately leading to apoptotic cell death. This is the first systematic study showing the involvement of each component of cdk inhibitor-cyclin-cdk machinery during cell cycle arrest and apoptosis of human prostate carcinoma cells by EGCG.