ZNF326 promotes malignant phenotype of glioma by up-regulating HDAC7 expression and activating Wnt pathway

Zinc-finger protein-326 (ZNF326) was initially found in the NIH3T3 cell line to regulate cell growth, however, the expression and underlying role of ZNF326 in human tumours, especially in glioma, is not fully understood.

Immunohistochemistry was applied to detect the expression of ZNF326 in glioma tissues, and statistical analysis was used to analyse the relationship between ZNF326 expression and clinicopathological factors. The effect of ZNF326 on glioma cells proliferation and invasion was conducted by functional experiments both in vivo and in vitro. Chromatin immunoprecipitation and dual-luciferase assays were performed to demonstrate that histone deacetylase enzyme-7 (HDAC7) is the target gene of ZNF326. Immunoblotting, real-time PCR, GST-pulldown and co-immunoprecipitation assays were used to clarify the underlying role of ZNF326 on Wnt pathway activation.

High nuclear expression of ZNF326 was observed in glioma cell lines and tissues, and closely related with advanced tumour grade in the patients. Moreover, ectopic ZNF326 expression promoted the proliferation and invasiveness of glioma cells. Mechanistically, ZNF326 could activate HDAC7 transcription by binding to a specific promoter region via its transcriptional activation domain and zinc-finger structures. The interaction of the up-regulated HDAC7 with β-catenin led to a decrease in β-catenin acetylation level at Lys-49, followed by a decrease in β-catenin phosphorylation level at Ser-45. These changes in β-catenin posttranscriptional modification levels promoted its redistribution and import into the nucleus. Additionally, ZNF326 directly associated with β-catenin in the nucleus, and enhanced the binding of β-catenin to TCF-4, serving as a co-activator in stimulating Wnt pathway.

Our findings elucidated ZNF326 promotes the malignant phenotype of human glioma via ZNF326-HDAC7-β-catenin signalling. This study reveals the vital role and mechanism of ZNF326 in the malignant progression of glioma, and provides the reference for finding biomarkers and therapeutic targets for glioma.