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. 2021 Apr 30:12:664003.
doi: 10.3389/fphar.2021.664003. eCollection 2021.

Theabrownin Induces Cell Apoptosis and Cell Cycle Arrest of Oligodendroglioma and Astrocytoma in Different Pathways

J Y Fu  1 , C X Jiang  1 , M Y Wu  1 , R Y Mei  1 , A F Yang  1 , H P Tao  1 , X J Chen  2 , J Zhang  3 , L Huang  4 , X F Zhao  1
Affiliations

Theabrownin Induces Cell Apoptosis and Cell Cycle Arrest of Oligodendroglioma and Astrocytoma in Different Pathways

J Y Fu et al. Front Pharmacol. .

Abstract

Theabrownin (TB), a natural compound present in the fresh leaves of green tea, is a potential antitumor agent. However, so far whether and how TB affects glioma is unclear. In this study, we investigated the effect of TB on astroglioma and oligodendroglioma cells. Surprisingly, TB significantly reduced the viabilities of HOG and U251 cells in a dose-dependent manner, which was accompanied by the upregulation of active-Casp-3, Bax, and PTEN; meanwhile, the antiapoptotic gene Bcl-2 was downregulated. In addition, TB treatment induced cell cycle arrest at the G1 and G2/M phases in HOG and U251 cells, respectively. TB treatment caused the downregulating of c-myc, cyclin D, CDK2, and CDK4 and upregulating of p21 and p27 in the HOG cell, while TB increased P53, p21, and p27 levels and decreased the levels of cell cycle regulator proteins such as CDK and cyclin A/B in the U251 cells. Therefore, the c-myc- and P53-related mechanisms were proposed for cell cycle arrest in these two glioma cell lines, respectively. Overall, our findings indicated that TB could be a novel candidate drug for the treatment of gliomas.

Keywords: apoptosis; astrocytoma; cell cycle; oligodendroglioma; theabrownin.

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Conflict of interest statement

Author JZ was employed by the company Theabio Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Effect of TB on cell viability of four glioma cell lines and the control primary culture astrocyte for 48 and 72 h determined by CCK-8 assay. (A) Effect of TB on cell viability of four glioma cell lines and the control primary culture astrocyte for 48 h determined by CCK-8 assay. (B) Effect of TB on cell viability of four glioma cell lines and the control primary culture astrocyte for 72 h determined by CCK-8 assay. Values are presented as mean ± SD (n = 3).
FIGURE 2
FIGURE 2
Morphological observation on TB-treated HOG and U251 cells by DAPI staining. Scale bar: 50 μm.
FIGURE 3
FIGURE 3
Observation of TB-induced apoptosis on HOG and U251 cells by TUNEL assay. Scale bar: 100 μm.
FIGURE 4
FIGURE 4
(A), (B): Flow cytometry analysis of HOG and U251 cells apoptosis by double staining with Annexin V-FITC and propidium iodide (PI). (C): Quantitative analysis of apoptosis induced by TB in HOG cells. (D): Quantitative analysis of apoptosis induced by TB in U251 cells.
FIGURE 5
FIGURE 5
Relative mRNA and protein expression of target genes in HOG cells with 48-h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of three replicates. (A): Relative mRNA expression of target genes in HOG cells with 48 h TB treatment at 25, 50, and 75 μg/ml. (B): Relative protein expression of target genes in HOG cells with 48 h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of three replicates. (C): Quantitative analysis the protein expression of p-AKT/AKT in HOG cells. (D): Quantitative analysis the protein expression of p-ERK/ERK in HOG cells.
FIGURE 6
FIGURE 6
Relative mRNA and protein expression of target genes in U251 cells with 48-h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of three replicates. (A): Relative mRNA expression of target genes in U251 cells with 48 h TB treatment at 25, 50, and 75 μg/ml. (B): Relative protein expression of target genes in U251 cells with 48 h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of three replicates. (C): Quantitative analysis the protein expression of p-AKT/AKT in U251 cells. (D): Quantitative analysis the protein expression of p-ERK/ERK in U251 cells.
FIGURE 7
FIGURE 7
(A): Effect of TB on the cell cycle of HOG cells determined by flow cytometry. (B): Quantitative analysis of cell cycle arrest induced by TB in HOG cells. (C): Relative protein expression of target genes in HOG cells with 48 h TB treatment at 25, 50, and 75 μg/ml. (D, E): Relative mRNA expression of p21 and p27 in HOG cells with 48 h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of triplicate.
FIGURE 8
FIGURE 8
(A): Effect of TB on the cell cycle of U251 cells determined by flow cytometry. (B): Quantitative analysis of cell cycle arrest induced by TB in U251 cells. (C): Relative protein expression of target genes in U251 cells with 48 h TB treatment at 25, 50, and 75 μg/ml. (D, E): Relative mRNA expression of p21 and p27 in U251 cells with 48 h TB treatment at 25, 50, and 75 μg/ml. Values are presented as mean ± SD of three replicates.
FIGURE 9
FIGURE 9
Apoptosis-inducing and cell cycle arrest mechanism of TB on HOG and U251 cells.
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