Grifolin induces apoptosis via inhibition of PI3K/AKT signalling pathway in human osteosarcoma cells.

Abstract

Grifolin, a natural biologically active substance isolated from the edible bodies of the mushroom Albatrellus confluens, has been shown to inhibit proliferation and induce apoptosis in several cancer cell lines. But the mechanisms remain poorly understood. In this study, we investigated the apoptosis-inducing effects and the mechanisms of grifolin on human osteosarcoma cells. Our results demonstrated that grifolin induced concentration- and time-dependent suppression of proliferation and induction of apoptosis in U2OS and MG63 osteosarcoma cell lines. Grifolin induced the release of cytochrome c accompanied by activation of caspase-9, caspase-3 and cleavage of poly (ADP-ribose) polymerase (PARP). In addition, z-VAD-fmk, a universal inhibitor of caspases, prevented caspase-3 activation and PARP cleavage and inhibted grifolin-induced cell growth inhibition. Furthermore, grifolin treatment resulted in a reduction in level of phosphorylated AKT, FOXO transcription factor, and glycogen synthase kinase 3 (GSK3). Knockdown of GSK3 with siRNA inhibited the apoptotic effects of grifolin. On the other hand, grifolin treatment down-regulated the expression of the inhibitor of apoptosis protein(IAP) in both osteosarcoma cells. Taken together, our results suggested that grifolin is able to suppress the phosphorylation of Akt and its substrates FOXO transcription factor and GSK3 in osteosarcoma cells causing the suppression of proliferation and induction of mitochondria- and caspase-dependent apoptosis.

• Authors: Song Jin, Rui-Ping Pang, Jing-Nan Shen, Gang Huang, Jin Wang, Jia-Guo Zhou
• Journal: Apoptosis : an international journal on programmed cell death (Apoptosis) Vol. 12 Issue 7 Pg. 1317-26 (Jul 2007) ISSN: 1360-8185 [Print] Netherlands
• PMID: 17333316 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amino Acid Chloromethyl Ketones
• Caspase Inhibitors
• Enzyme Inhibitors
• FOXO1 protein, human
• Forkhead Box Protein O1
• Forkhead Transcription Factors
• RNA, Small Interfering
• Terpenes
• benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
• grifolin
• Cytochromes c
• PARP1 protein, human
• Poly (ADP-Ribose) Polymerase-1
• Poly(ADP-ribose) Polymerases
• Phosphatidylinositol 3-Kinases
• Oncogene Protein v-akt
• Caspases

Topics

• Amino Acid Chloromethyl Ketones (pharmacology)
• Apoptosis
• Caspase Inhibitors
• Caspases (metabolism)
• Cell Line, Tumor
• Cytochromes c (metabolism)
• Enzyme Inhibitors (pharmacology)
• Forkhead Box Protein O1
• Forkhead Transcription Factors (metabolism)
• Humans
• Mitochondria (metabolism)
• Oncogene Protein v-akt (metabolism)
• Osteosarcoma (metabolism, pathology)
• Phosphatidylinositol 3-Kinases (metabolism)
• Poly (ADP-Ribose) Polymerase-1
• Poly(ADP-ribose) Polymerases (metabolism)
• RNA, Small Interfering
• Signal Transduction (drug effects)
• Terpenes (pharmacology)