Theanine, an antitumor promoter, induces apoptosis of tumor cells via the mitochondrial pathway

Xin,Yinqiang; Ben,Peiling; Wang,Qi; Zhu,Yanyan; Yin,Zhimin; Luo,Lan

doi:10.3892/mmr.2018.9459

Theanine, an antitumor promoter, induces apoptosis of tumor cells via the mitochondrial pathway

Authors:
- Yinqiang Xin
- Peiling Ben
- Qi Wang
- Yanyan Zhu
- Zhimin Yin
- Lan Luo
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Affiliations: Jiangsu Province Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, Jiangsu 210023, P.R. China, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210093, P.R. China
Published online on: September 5, 2018 https://doi.org/10.3892/mmr.2018.9459
Pages: 4535-4542

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Abstract

Theanine, an active component of green tea (Camellia sinensis), is considered a modulator of chemotherapy. To further investigate the anticancer activity of theanine, the present study investigated the cytotoxic effect of theanine at the concentration of 600 µg/ml, in the human HepG2 hepatoblastoma and HeLa adenocarcinoma cell lines, in comparison with the normal L02, H9c2 and HEK293 cell lines using a MTT assay. It was found that theanine induced cell death in the tumor cells, but not in the normal cells. Notably, when glutamine was restricted or reduced in the cell culture medium, the cell death induced by theanine was significantly enhanced. A terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assay indicated that DNA damage was induced in theanine‑treated HepG2 cells. Further experiments demonstrated that theanine caused HepG2 cell apoptosis through the mitochondrial pathway, with a loss of membrane potential and the release of apoptosis‑inducing factor, endonuclease G and cytochrome c. Western blot analysis and caspase activity detection also revealed that caspase‑9 and caspase‑3 were activated, whereas caspase‑8 remained inactive. These observations suggested that theanine exerted potent cytotoxicity on tumor cells when glutamine was restricted.

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