Clinicopathological and biological significance of aberrant activation of glycogen synthase kinase-3 in ovarian cancer

Background: Glycogen synthase kinase-3 (GSK-3) plays an important role in human cancer. The aim of this study is to evaluate the clinicopathological significance of expression of GSK3a/and pGSK-3a/Tyr279/216 in patients with epithelial ovarian cancer and to investigate whether GSK-3 inhibition can influence cell viability and tumor growth of ovarian cancer. Methods: Immunohistochemistry was used to examine expression of GSK-3a/ and pGSK-3a/Tyr279/216 in 71 human epithelial ovarian cancer tissues and correlations between protein expression, and clinicopathological factors were analyzed. Cell viability was determined by 3-(4,5dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay following exposure of ovarian carcinoma cells to pharmacological inhibitors of GSK-3 or GSK-3 small interfering RNA. In vivo validation of tumor growth inhibition was performed with xenograft mice. Results: The expression levels of GSK-3a/ and pGSK-3a/Tyr279/216 in ovarian cancers were significantly higher than those in benign tumors. High expression of GSK-3a/was more likely to be found in patients with advanced International Federation of Gynecology and Obstetrics (FIGO) stages and high serum cancer antigen 125. Higher expression of pGSK-3a/Tyr279/216 was associated with advanced FIGO stages, residual tumor mass, high serum cancer antigen 125, and poor chemoresponse. Worse overall survival was revealed by Kaplan-Meier survival curves in patients with high expression of GSK-3a/or pGSK-3a/Tyr279/216. Multivariate analysis indicated that FIGO stage, GSK-3a/expression, and pGSK-3a/Tyr279/216 expression were independent prognostic factors for overall survival. GSK-3 inhibition by lithium chloride, 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8), or GSK-3 small interfering RNA can decrease viability of SKOV3 and SKOV3-TR30 ovarian cancer cells. Additionally, lithium chloride-treated SKOV3 xenograft mice had a significant reduction in tumor growth compared with control-treated animals. Conclusion: Our findings suggest that overexpression and aberrant activation of GSK-3 may contribute to progression and poor prognosis in ovarian cancer. Inhibition of GSK-3 may be a potential therapy for ovarian cancer.