Glycogen Synthase Kinase-3β, NF-κB Signaling, and Tumorigenesis of Human Osteosarcoma

Abstract

BackgroundGlycogen synthase kinase-3β (GSK-3β), a serine/threonine protein kinase, may function as a tumor suppressor or an oncogene, depending on the tumor type. We sought to determine the biological function of GSK-3β in osteosarcoma, a rare pediatric cancer for which the identification of new therapeutic targets is urgent.MethodsWe used cell viability assays, colony formation assays, and apoptosis assays to analyze the effects of altered GSK-3β expression in U2OS, MG63, SAOS2, U2OS/MTX300, and ZOS osteosarcoma cell lines. Nude mice (n = 5–8 mice per group) were injected with U2OS/MTX300, and ZOS cells to assess the role of GSK-3β in osteosarcoma growth in vivo and to evaluate the effects of inhibitors and/or anticancer drugs on tumor growth. We used an antibody array, polymerase chain reaction, western blotting, and a luciferase reporter assay to establish the effect of GSK-3β inhibition on the nuclear factor-κB (NF-κB) pathway. Immunochemistry was performed on primary tumor specimens from osteosarcoma patients (n = 74) to determine the relationship of GSK-3β activity with overall survival.ResultsOsteosarcoma cells with low levels of inactive p-Ser9-GSK-3β formed colonies in vitro and tumors in vivo more readily than cells with higher levels and cells in which GSK-3β had been silenced formed fewer colonies and smaller tumors than parental cells. Silencing or pharmacological inhibition of GSK-3β resulted in apoptosis of osteosarcoma cells. Inhibition of GSK-3β resulted in inhibition of the NF-κB pathway and reduction of NF-κB-mediated transcription. Combination treatments with GSK-3β inhibitors, NF-κB inhibitors, and chemotherapy drugs increased the effectiveness of chemotherapy drugs in vitro and in vivo. Patients whose osteosarcoma specimens had hyperactive GSK-3β, and nuclear NF-κB had a shorter median overall survival time (49.2 months) compared with patients whose tumors had inactive GSK-3β and NF-κB (109.2 months).ConclusionGSK-3β activity may promote osteosarcoma tumor growth, and therapeutic targeting of the GSK-3β and/or NF-κB pathways may be an effective way to enhance the therapeutic activity of anticancer drugs against osteosarcoma.

GSK3 Protein Positively Regulates Type I Insulin-like Growth Factor Receptor through Forkhead Transcription Factors FOXO1/3/4

“…Therefore, GSK3␤ and mTORC1 may positively regulate p70S6K under different conditions. In addition to a positive role for GSK3␤ in p70S6K activation, GSK3␤ stimulates NF-B activity thereby promoting osteosarcoma cells survival (49). Our study highlights a positive role for GSK3␤ in IGF-IR expression and signaling.…”

Review of the Molecular Pathogenesis of Osteosarcoma

“…Similar results with other studies, combination treatments with GSK-3β inhibitors, NF-κB inhibitors, and chemotherapy drugs increased the effectiveness of chemotherapy drugs in vitro and in vivo (Tang et al, 2012). Patients whose OSA specimens had hyperactive GSK-3β, and nuclear NF-κB had a shorter median overall survival time (49.2 months) compared with patients whose tumors had inactive GSK-3β and NF-κB (109.2 months) (Tang et al, 2012). GSK-3β activity may promote OSA tumor growth, and therapeutic targeting of the GSK-3β and/or NF-κB pathways may be an effective way to enhance the therapeutic activity of anticancer drugs against OSA.…”

“…Inhibition of GSK-3β resulted in inhibition of the NF-κB pathway and reduction of NF-κB-mediated transcription (Hoeflich et al, 2000). Similar results with other studies, combination treatments with GSK-3β inhibitors, NF-κB inhibitors, and chemotherapy drugs increased the effectiveness of chemotherapy drugs in vitro and in vivo (Tang et al, 2012). Patients whose OSA specimens had hyperactive GSK-3β, and nuclear NF-κB had a shorter median overall survival time (49.2 months) compared with patients whose tumors had inactive GSK-3β and NF-κB (109.2 months) (Tang et al, 2012).…”

Degalactotigonin, a Natural Compound from Solanum nigrum L., Inhibits Growth and Metastasis of Osteosarcoma through GSK3β Inactivation–Mediated Repression of the Hedgehog/Gli1 Pathway

“…After 8 days, the mice were randomly separated into three groups. For the osteosarcoma xenograft growth of orthotopic animal model, ZOS cells were used as described previously (22). After 14 days, the mice were randomly separated into the three groups.…”