Increased Argonaute 2 Expression in Gliomas and its Association with Tumor Progression and Poor Prognosis

Abstract

<b>Background:</b> Previous studies have showed that argonaute 2 is a potential factor related to genesis of severalcancers, however, there have been no reports concerning gliomas. <br/><b>Methods</b>: Paraffin specimens of 129 brainglioma cases were collected from a hospital affiliated to Binzhou Medical University from January 2008 to July2013. We examined both argonaute 2 mRNA and protein expression by real-time quantitative PCR (qRT-PCR),Western blot analysis, and immunohistochemistry (IHC). The survival curves of the patients were determinedusing the Kaplan-Meier method and Cox regression, and the log-rank test was used for statistical evaluations.<br/><b>Results</b>: Both argonaute 2 mRNA and protein were upregulated in high-grade when compared to low-gradetumor tissues. Multivariate analysis revealed that argonaute 2 protein expression was independently associatedwith the overall survival (HR=4.587, 95% CI: 3.001-6.993; P=0.002), and that argonaute 2 protein expressionand WHO grading were independent prognostic factors for progression-free survival (HR=4.792, 95% CI:3.993-5.672; P<0.001, and HR=2.109, 95% CI: 1.278-8.229; P=0.039, respectively). Kaplan-Meier analysis withthe log-rank test indicated that high argonaute 2 protein expression had a significant impact on overall survival(P=0.0169) and progression-free survival (P=0.0324). <br/><b>Conclusions</b>: The present study showed that argonaute 2expression is up-regulated in gliomas. Argonaute 2 might also serve as a novel prognostic marker.