Green tea polyphenol epigallocatechin‐3‐gallate enhances 5‐fluorouracil‐induced cell growth inhibition of hepatocellular carcinoma cells

Department of Hepatobiliary Surgery, the Second Affiliated Hospital of Guangzhou Medical University Department of Ophthalmology, Guangzhou No. 8 People's Hospital, Guangzhou, China.
Hepatology Research (Impact Factor: 2.74). 01/2012; 42(5):494-501. DOI: 10.1111/j.1872-034X.2011.00947.x
Source: PubMed


Aim: 5-Fluorouracil (5-FU) is one of the most commonly used chemotherapeutic drugs. Resistance to 5-FU is a major cause of chemotherapy failure in advanced-stage hepatocellular carcinoma (HCC). Green tea polyphenol Epigallocatechin-3-gallate (EGCG) plays a critical role in growth inhibition and apoptotic induction in HCC cell lines. The aim of this study is to investigate whether EGCG can enhance 5-FU-induced cell growth inhibition and to explore its potential mechanisms.
Methods: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to evaluate cell growth. Western blotting analysis was performed to detect the proteins expression in Hep3B cells. Small interfering RNA was used to suppress cyclooxygenase-2 (COX-2) expression. Furthermore, enzyme linked immunosorbent assay was used to test the prostaglandin E2 (PGE2) production in cell cultures.
Results: Epigallocatechin-3-gallate augmented the anti-tumor effect of 5-FU in Hep3B cells. Significant difference was observed between the treated groups and the control group (P < 0.05). EGCG (its concentrations at over 5 µmol/L) combined with 5-FU presented a synergic effect. Furthermore, the combination of EGCG and 5-FU abrogated the COX-2 overexpression and PGE2 secretion induced by 5-FU. The upregulation of COX-2 expression decreased the phosphorylation of Akt (Thr308) expression. These appeared to be followed by the AMPK hyperactivation.
Conclusion: Epigallocatechin-3-gallate sensitizes HCC cells to 5-FU antitumor activity, and the combination of EGCG and 5-FU exhibits synergism in chemo-resistant cancer cells. The results suggest potential novel therapies for the treatment of advanced-stage liver cancer.

7 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: Over the past three years numerous patents and patent applications have been published relating to scientific advances in the use of the green tea polyphenol epigallocatechin gallate (EGCG) (the most abundant, and bioactive compound in green tea) and its analogs as anticancer agents. EGCG affects multiple molecular targets involved in cancer cell proliferation and survival; however, polyphenolic catechins, such as EGCG, generally exhibit poor oral bioavailability. Since the anticancer activity of polyphenols largely depends on their susceptibility to biotransformation reactions, numerous EGCG derivatives, analogs and prodrugs have been designed to improve the stability, bioavailability and anticancer potency of the native compound. Areas covered: This review focuses on the applications of EGCG and its analogs, derivatives and prodrugs in the prevention and treatment of human cancers. A comprehensive description of patents related to EGCG and its derivatives, analogs and prodrugs and their uses as anticancer agents is included. Expert opinion: EGCG targets multiple essential survival proteins and pathways in human cancer cells. Because it is unstable physiologically, numerous alterations to the EGCG molecule have been patented, either to improve the integrity of the native compound or to generate a more stable yet similarly efficacious molecule. EGCG and its derivatives, analogs and prodrugs could be developed into future drugs for chemoprevention, chemosensitization, radiosensitization and/or cancer interception.
    No preview · Article · Dec 2012 · Expert Opinion on Therapeutic Patents
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Despite the advances in biomedical research and clinical applications, cancer remains a leading cause of death worldwide. Given the limitations of conventional chemotherapeutics, including serious toxicities and reduced quality of life for patients, the development of safe and efficacious alternatives with known mechanism of action is much needed. Prevention of cancer through dietary intervention may hold promise and has been investigated extensively in the recent years. AMP-activated protein kinase (AMPK) is an energy sensor that plays a key role in the regulation of protein and lipid metabolism in response to changes in fuel availability. When activated, AMPK promotes energy-producing catabolic pathways while inhibiting anabolic pathways, such as cell growth and proliferation - thereby antagonizing carcinogenesis. Other anti-cancer effects of AMPK may include promoting autophagy and DNA repair upon UVB damage. In the last decade, interest in AMPK has grown extensively as it emerged as an attractive target molecule for cancer prevention and treatment. Among the latest developments is the activation of AMPK by naturally occurring dietary constituents and plant products - termed phytochemicals. Owing to their efficacy and safety, phytochemicals are considered as an alternative to the conventional harmful chemotherapy. The rising popularity of using phytochemicals for cancer prevention and therapy is supported by a substantial progress in identifying the molecular pathways involved, including AMPK. In this article, we review the recent progress in this budding field that suggests AMPK as a new molecular target in the prevention and treatment of cancer by phytochemicals.
    Full-text · Article · Jul 2013 · Frontiers in Oncology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hepatocellular carcinoma (HCC) is the most common type of liver cancer with high mortality worldwide. Traditional chemotherapy for HCC is not widely accepted by clinical practitioners because of its toxic side effects. Thus, there is a need to identify chemotherapeutic drugs against HCC. AMP-activated protein kinase (AMPK) is a biologic sensor for cellular energy status that acts a tumor suppressor and a potential cancer therapeutic target. The traditional Vietnamese medicinal plant Croton tonkinensis shows cytotoxicity in various cancer cells; however, its anticancer mechanism remains unclear. In this study, we determined whether the ent-kaurane diterpenoid ent-18-acetoxy-7β-hydroxy kaur-15-oxo-16-ene (CrT1) isolated from this plant plays a role as a chemotherapeutic drug targeting AMPK. CrT1 blocked proliferation in dose- and time-dependent manners in human hepatocellular carcinoma SK-HEP1 cells. CrT1 induced sub-G(1) arrest and caspase-dependent apoptosis. CrT1 activated caspase-3, -7, -8, -9, and poly(ADP-ribose) polymerase, and its effect was inhibited by z-VAD-fmk suppressing caspase-3 cleavage. CrT1 induced increases in p53 and Bax levels but decreased Bcl(2) levels. In addition, CrT1 resulted in increased translocation of cytochrome c into the cytoplasm. We showed that CrT1-activated AMPK activation was followed by modulating the mammalian target of rapamycin/p70S6K pathway and was inactivated by treating cells with compound C. Treatment with CrT1 and aminoimidazole carboxamide ribonucleotide (AICAR) synergistically activated AMPK. CrT1-induced AMPK activation regulated cell viability and apoptosis. These results suggest that CrT1 is a novel AMPK activator and that AMPK activation in SK-HEP1 cells is responsible for CrT1-induced anticancer activity including apoptosis.
    No preview · Article · Jan 2013 · Biological & Pharmaceutical Bulletin
Show more