Glioma is the most common human brain cancer and has poor prognosis. Messenger RNA profiling identified that sineoculis homeobox homolog 1 (Six1) is dysregulated in glioma tumor progenitor cells from glial progenitor cells isolated from normal white matter. However, the expression and role of Six1 in glioma remains unclear. The purpose of the present study was to investigate the expression level of Six1 in glioma tissues and the association between Six1 expression and clinicopathological characteristics and prognosis of gliomas. The Six1 protein was detected by immunohistochemistry in 163 glioma tissues of distinct malignancy grades, and Kaplan-Meier survival analysis was performed to assess the prognosis of the patients. The Six1 protein was stained in 49.1% (80 out of 163) of the glioma tissues, including 34.2% of low-grade [World Health Organization (WHO) I/II] gliomas and 80.8% of high-grade (WHO III/IV) gliomas. Normal brain tissues rarely expressed the Six1 protein. In addition, Six1 expression was significantly associated with WHO grade (P<0.001). According to the log-rank test and Cox regression model, Six1 may be suggested as an independent prognostic factor, in addition to the WHO grade. Overall, Six1 protein expression varies between different grades of glioma and is associated with the WHO grade. Upregulation of Six1 is more frequent in high-grade glioma and is an independent prognostic factor of poor clinical outcome.
Keywords: Six1; glioma; immunohistochemistry; prognosis.