SOX7 is associated with the suppression of human glioma by HMG-box dependent regulation of Wnt/β-catenin signaling

SOX7 has been recently recognized as a tumor suppressor belonging to the SOX (SRY-related HMG-box) family of a transcription factor. However, its role in human gliomas is unknown. Our study showed that SOX7 expression was significantly downregulated in human gliomas. Statistical analysis showed that SOX7 suppression was associated with higher histological grades of tumors in glioma tissues. SOX7 could suppress tumor properties both in vivo and in vitro, and depletion of the HMG domain abolishes its tumor suppressive roles. In vitro assays demonstrated that SOX7 could downregulate Wnt/β-catenin transcription and decrease the expression of Cyclin D1 and c-Myc, while the mutant SOX7 lost these functions. These results suggested that the HMG-box is a key domain of SOX7 for negatively regulating the Wnt/β-catenin signaling pathway when functioning as a tumor suppressor in a glioma.