The glycogen synthase kinase-3β/nuclear factor-kappa B pathway is involved in cinobufagin-induced apoptosis in cultured osteosarcoma cells.

Abstract

Cinobufagin, a major component of cinobufacini (huachansu), is an important cardenolidal steroid. Several studies have suggested that cinobufagin has potent anti-cancer effects. The present study examines the apoptosis-inducing activity and the underlying mechanism of action of cinobufagin in osteosarcoma (OS) cells. Our results showed that cinobufagin potently inhibited the proliferation of U2OS, MG63 and SaOS-2 cells. Significant increases in G2/M cell-cycle arrest and apoptosis in OS cells were also observed. The expression levels of several apoptotic proteins were assessed after cinobufagin treatment in U2OS cells. Among them, xIAP, cIAP-1, survivin and Bcl-2 levels decreased remarkably, while the levels of Bax and cleaved-PARP increased. Furthermore, we validated the inhibition of GSK-3β/NF-κB signaling following cinobufagin treatment. Western blots showed a decrease in nuclear p65 protein expression after exposure to different concentrations of cinobufagin, while the phosphorylation of GSK-3β was simultaneously increased. Transduction with constitutively active forms of GSK-3β could protect against the downregulation of p65 and upregulation of cleaved-PARP that are induced by cinobufagin treatment. However, combined treatment with cinobufagin and SB216367 resulted in a significant reduction in p65 and an increase in cleaved-PARP in U2OS cells. Altogether, these results show that cinobufagin is a promising agent for the treatment of OS. These studies are the first to reveal the involvement of the GSK-3β/NF-κB pathway in cinobufagin-induced apoptosis.

• Authors: Jun-Qiang Yin, Lili Wen, Liang-Cai Wu, Zhen-Hua Gao, Gang Huang, Jin Wang, Chang-Ye Zou, Ping-Xian Tan, Bi-Cheng Yong, Qiang Jia, Jing-Nan Shen
• Journal: Toxicology letters (Toxicol Lett) Vol. 218 Issue 2 Pg. 129-36 (Apr 12 2013) ISSN: 1879-3169 [Electronic] Netherlands
• PMID: 23164673 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Chemical References

• Amphibian Venoms
• Antineoplastic Agents
• Apoptosis Regulatory Proteins
• Bufanolides
• NF-kappa B
• RELA protein, human
• Transcription Factor RelA
• huachansu
• Poly(ADP-ribose) Polymerases
• GSK3B protein, human
• Glycogen Synthase Kinase 3 beta
• Glycogen Synthase Kinase 3
• cinobufagin

Topics

• Amphibian Venoms (analysis, chemistry)
• Antineoplastic Agents (pharmacology)
• Apoptosis (drug effects)
• Apoptosis Regulatory Proteins (genetics, metabolism)
• Bufanolides (pharmacology)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Down-Regulation
• Glycogen Synthase Kinase 3 (genetics, metabolism)
• Glycogen Synthase Kinase 3 beta
• Humans
• NF-kappa B (genetics, metabolism)
• Osteosarcoma (metabolism)
• Phosphorylation
• Poly(ADP-ribose) Polymerases (genetics, metabolism)
• Signal Transduction
• Transcription Factor RelA (genetics, metabolism)
• Transfection
• Up-Regulation