Probucol suppresses human glioma cell proliferation in vitro via ROS production and LKB1-AMPK activation
Abstract
Yong-sheng JIANG1, Jing-an LEI2, Fang FENG2, Qi-ming LIANG2, Fu-rong WANG2, *
1Tumor Center, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; 2Department of Neurology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
Aim: Probucol, an anti-hyperlipidemic drug, has been reported to exert antitumor activities at various stages of tumor initiation, promotion and progression. In this study we examined whether the drug affected glioma cell growth in vitro and the underlying mechanisms.
Methods: Human glioma U87 and glioblastoma SF295 cell lines were used. Cell proliferation was accessed using the cell proliferation assay and BrdU incorporation. The phosphorylation of AMPK, liver kinase B1 (LKB1) and p27Kip1 was detected by Western blot. The activity of 26S proteasome was assessed with an in situ fluorescent substrate. siRNAs were used to suppress the expression of the relevant signaling proteins.
Results: Treatment of U87 glioma cells with probucol (10–100 μmol/L) suppressed the cell proliferation in dose- and time-dependent manners. Meanwhile, probucol markedly increased the ROS production, phosphorylation of AMPK at Thr172 and LKB1 at Ser428 in the cells. Furthermore, probucol significantly decreased 26S proteasome activity and increased p27Kip1 protein level in the cells in an AMPK-dependent manner. Probucol-induced suppression of U87 cell proliferation could be reversed by pretreatment with tempol (a superoxide dismutase mimetic), MG132 (proteasome inhibitor) or compound C (AMPK inhibitor), or by gene silencing of LKB1, AMPK or p27Kip1. Similar results were observed in probucol-treated SF295 cells.
Conclusion: Probucol suppresses human glioma cell proliferation in vitro via ROS production and LKB1-AMPK activation, which reduces 26S proteasome-dependent degradation of p27Kip1.
Keywords: glioma; probucol; anti-proliferation; ROS; AMPK; LKB1; 26S proteasome; p27Kip1; tempol; MG132; compound C
This study was supported by the National Natural Science Foundation of China (No 81371222).
* To whom correspondence should be addressed.
E-mail wang010020@163.com
Received 2014-03-04 Accepted 2014-07-28
Keywords:
1Tumor Center, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; 2Department of Neurology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
Aim: Probucol, an anti-hyperlipidemic drug, has been reported to exert antitumor activities at various stages of tumor initiation, promotion and progression. In this study we examined whether the drug affected glioma cell growth in vitro and the underlying mechanisms.
Methods: Human glioma U87 and glioblastoma SF295 cell lines were used. Cell proliferation was accessed using the cell proliferation assay and BrdU incorporation. The phosphorylation of AMPK, liver kinase B1 (LKB1) and p27Kip1 was detected by Western blot. The activity of 26S proteasome was assessed with an in situ fluorescent substrate. siRNAs were used to suppress the expression of the relevant signaling proteins.
Results: Treatment of U87 glioma cells with probucol (10–100 μmol/L) suppressed the cell proliferation in dose- and time-dependent manners. Meanwhile, probucol markedly increased the ROS production, phosphorylation of AMPK at Thr172 and LKB1 at Ser428 in the cells. Furthermore, probucol significantly decreased 26S proteasome activity and increased p27Kip1 protein level in the cells in an AMPK-dependent manner. Probucol-induced suppression of U87 cell proliferation could be reversed by pretreatment with tempol (a superoxide dismutase mimetic), MG132 (proteasome inhibitor) or compound C (AMPK inhibitor), or by gene silencing of LKB1, AMPK or p27Kip1. Similar results were observed in probucol-treated SF295 cells.
Conclusion: Probucol suppresses human glioma cell proliferation in vitro via ROS production and LKB1-AMPK activation, which reduces 26S proteasome-dependent degradation of p27Kip1.
Keywords: glioma; probucol; anti-proliferation; ROS; AMPK; LKB1; 26S proteasome; p27Kip1; tempol; MG132; compound C
This study was supported by the National Natural Science Foundation of China (No 81371222).
* To whom correspondence should be addressed.
E-mail wang010020@163.com
Received 2014-03-04 Accepted 2014-07-28