Biomolecules & Therapeutics  
Induction of Cell Death by Betulinic Acid through Induction of Apoptosis and Inhibition of Autophagic Flux in Microglia BV-2 Cells
Jeongbin Seo1, Juneyoung Jung1, Dae Sik Jang1, Joungmok Kim2 and Jeong Hee Kim1,2,*
1Department of Life and Nanopharmaceutical Sciences, Graduate School,
2Department of Oral Biochemistry and Molecular Biology, School of Dentistry, Kyung Hee University, Seoul 02447, Republic of Korea
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Received: November 15, 2016; Revised: December 15, 2016; Accepted: December 27, 2016; Published online: March 10, 2017.
© The Korean Society of Applied Pharmacology. All rights reserved.

Betulinic acid (BA), a natural pentacyclic triterpene found in many medicinal plants is known to have various biological activity including tumor suppression and anti-inflammatory effects. In this study, the cell-death induction effect of BA was investigated in BV-2 microglia cells. BA was cytotoxic to BV-2 cells with IC50 of approximately 2.0 μM. Treatment of BA resulted in a dosedependent chromosomal DNA degradation, suggesting that these cells underwent apoptosis. Flow cytometric analysis further confirmed that BA-treated BV-2 cells showed hypodiploid DNA content. BA treatment triggered apoptosis by decreasing Bcl-2 levels, activation of capase-3 protease and cleavage of PARP. In addition, BA treatment induced the accumulation of p62 and the increase in conversion of LC3-I to LC3-II, which are important autophagic flux monitoring markers. The increase in LC3-II indicates that BA treatment induced autophagosome formation, however, accumulation of p62 represents that the downstream autophagy pathway is blocked. It is demonstrated that BA induced cell death of BV-2 cells by inducing apoptosis and inhibiting autophagic flux. These data may provide important new information towards understanding the mechanisms by which BA induce cell death in microglia BV-2 cells.
Keywords: Betulinic acid, Apoptosis, Autophagy, Microglia BV-2 cell

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