Glycogen synthase kinase-3?, NF-?B signaling, and tumorigenesis of human osteosarcoma.

ABSTRACT: Glycogen synthase kinase-3? (GSK-3?), 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-3? in osteosarcoma, a rare pediatric cancer for which the identification of new therapeutic targets is urgent.We used cell viability assays, colony formation assays, and apoptosis assays to analyze the effects of altered GSK-3? 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-3? 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-3? inhibition on the nuclear factor-?B (NF-?B) pathway. Immunochemistry was performed on primary tumor specimens from osteosarcoma patients (n = 74) to determine the relationship of GSK-3? activity with overall survival.Osteosarcoma cells with low levels of inactive p-Ser9-GSK-3? formed colonies in vitro and tumors in vivo more readily than cells with higher levels and cells in which GSK-3? had been silenced formed fewer colonies and smaller tumors than parental cells. Silencing or pharmacological inhibition of GSK-3? resulted in apoptosis of osteosarcoma cells. Inhibition of GSK-3? resulted in inhibition of the NF-?B pathway and reduction of NF-?B-mediated transcription. Combination treatments with GSK-3? inhibitors, NF-?B inhibitors, and chemotherapy drugs increased the effectiveness of chemotherapy drugs in vitro and in vivo. Patients whose osteosarcoma specimens had hyperactive GSK-3?, and nuclear NF-?B had a shorter median overall survival time (49.2 months) compared with patients whose tumors had inactive GSK-3? and NF-?B (109.2 months).GSK-3? activity may promote osteosarcoma tumor growth, and therapeutic targeting of the GSK-3? and/or NF-?B pathways may be an effective way to enhance the therapeutic activity of anticancer drugs against osteosarcoma.

SUBMITTER: Tang QL 

PROVIDER: S-EPMC3352834 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature