Norcantharidin blocks Wnt/-catenin signaling via promoter demethylation of WIF-1 in glioma

Abstract

Glioma is one of the most common primary intracranial tumors, and the prognosis is poor even though much treatment management is employed. Wnt/-catenin signaling has been reported to be associated with glioma. Norcantharidin (NCTD) is the demethylated analog of cantharidin isolated from blister beetles, and it is reported to possess anticancer activity but less nephrotoxicity than cantharidin. Accordingly, we aimed to investigate NCTD as an anti-neoplastic drug that inhibits the Wnt/catenin pathway via promoter demethylation of Wnt inhibitory factor-1 (WIF-1) in glioma growth in vitro. In the present study, we report that NCTD inhibited cell proliferation, induced apoptosis and cell cycle arrest, and suppressed cell migration and invasion in vitro. Moreover, we observed that the expression levels of WIF-1 mRNA and protein in the NCTD-treated cells were increased significantly compared with these levels in the negative control (NC) cells. Promoter demethylation was observed in the NCTDtreated cells. In contrast, aberrant methylation was observed in the NC cells. Additionally, more investigation revealed that NCTD suppressed activity of Wnt/-catenin signaling and transcription of catenin/TCF-4. Furthermore, the expression of apoptosis-related proteins Bcl-2 and cleaved caspase-3 indicated significant cell apoptosis. We provide initial evidence that NCTD reactivates WIF-1 from a methylation state, and downregulates canonical Wnt/-catenin signaling. Our findings revealed that NCTD is effective for glioma in vitro and may be a new therapeutic option in vivo.