Effect of tea polyphenols and EGCG on nasopharyn-geal carcinoma cell proliferation and the mechanisms involved

Fei Jun Luo, Zhi Hu, Xi Yun Deng, Yan Zhao, Liang Zeng, Zi Gang Dong, Wei Yi, Ya Cao

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6 Scopus citations

Abstract

Objective: Tea polyphenols present in green tea show cancer chemopreventive effects in many tumor models. Epidemiological studies have also suggested that green tea consumption might be effective in the prevention of certain human cancers. In the present study, we investigated the molecular mechanisms of the inhibition of cell proliferation by tea polyphenols in nasopharyngeal carcinoma (NPC) cell line CNE1-LMP1. Methods: CNE1-LMP1 cells were treated with tea polyphenols at various doses (0, 25, 50, 100, 200 μg/ml) for 24 hours, the morphology of cells was observed by light microscopy, and cell survival rate was determined by MTT assay. At the same time, cell cycle of CNE1-LMP1 was analyzed by flow cytometry. Cyclin D1 transcription was analyzed by cyclin D1 promoterluciferase reporter system and expression of cyclin D1 protein by Western blot analysis. Transactivities of NF-κB and AP-1 was analyzed by Dual-fluorescence reporter gene system. Results: After treatment of CNE1-LMP1 cells with tea polyphenols, the number of proliferating cells was obviously decreased as determined by light microscopy and MTT assay (from 100% to 89.4%, 83.3%, 74.8% and 38.1%). With the increase of tea polyphenols concentrations, the number of cells in S-phase was obviously decreased, and the number of cells in G1-phase from 22.20% to 13.16%, and the number of cells in G0/G1 phase was elevated from 68.5% to 74.08%. It suggests that tea polyphenols could arrest the cell cycle at both of the two checkpoints. Furthermore, transcription and were obviously declined 7-8 folds (100-200 μg/ml tea polyphenols or EGCG group) and expression of cyclin D1 protein also decreased in a dose-dependent manner. Transactivities of NF-κB and AP-1 were obviously down-regulated in CNE1-LMP1 cells. Conclusion: Green tea polyphenols could inhibit cell proliferation, by suppressing the activity of NF-κB and AP-1, and by down-regulation of the transcription of cyclin D1.

Original languageEnglish (US)
Pages (from-to)235-242
Number of pages8
JournalChinese Journal of Cancer Research
Volume13
Issue number4
DOIs
StatePublished - 2001

Bibliographical note

Funding Information:
Objective: Tea polyphenols present in green tea show cancer chemopreventive effects in many tumor models. Epidemiological studies have also suggested that green tea consumption might be effective in the prevention of certain human cancers. In the present study, we investigated the molecular mechanisms of the inhibition of cell proliferation by tea polyphenols in nasopharyngeal carcinoma (NPC) cell line CNE1-LMP1. Methods: CNE1-LMP1 cells were treated with tea polyphenols at various doses (0, 25, 50, 100, 200 pg/ml) for 24 hours, the morphology of cells was observed by Received date: June 19, 2001; Accepted date: September 26, 2001. Foundation items: This work was supported by National Natural Science Foundation of China(No. 30000087), "973" National Key Basic Research Program of China(No. G1998051201), and the National Scientific Research Foundation for Excellent Young Scientist of China(No. 39525022). * ~ u t h otor whom correspondence should be addressed. Phone: (86-73 1)-4805448; Fax: (86-73 1)-4470589; E-mail: [email protected] Biography: LUO Fei-jun(1968-), doctor of medicine, assistant professor, works at Cancer Research Institute, Xiang-Ya School of Medicine, Central-South University, majors in cell biology. The abbreviations used are: TP, tea polyphenols; EGCG, (-)-epigallocatechin-3-gallate; AP-I, activator protein-1; BSA, bovine serum album; LMP1, Epstein-Ban virus latent membrane protein 1; NF-KB, nuclear factor kappa B; DMSO, dimethyl sulfoxide; PBS, phosphate buffered saline; NPC, nasopharyngeal carcinoma; JNK, c-jun-NHz-terminal kinase.

Keywords

  • AP-1
  • Cyclin D1
  • Epstein-Barr virus
  • LMP1
  • NF-κ B
  • Nasopharyngeal carcinoma (NPC)
  • Tea polyphenols (TP)

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