β-Catenin is important for cancer stem cell generation and tumorigenic activity in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors with poor prognosis and recurrence in South China. The hard eradication of NPC in clinic is predominantly due to cancer stem cells (CSCs). Increasing evidence revealed that the aberrant activation of Wnt/beta-catenin was positively correlated with the produce of CSCs. To further investigate the effect of beta-catenin on CSCs and tumorigenesis in NPC, a CNE2 cell line (pLKO. 1-sh-beta-catenin-CNE2) with stably suppressed expression of beta-cateninwas used in this study. The expressions of biomarkers in CSCs including c-myc, Nanog, Oct3/4, Sox2, EpCAM as well as adhesion-related proteins like E-cadherin and vimentin were analyzed by western blot analysis and immunofluorescent staining. The proliferation and migration abilities were investigated by MTT assay and Transwell assay, respectively. Cell cycle was analyzed by flowcytometry. Finally, xenograft was performed to determine the effect of beta-catenin on oncogenesis in vivo. Results showed that the expressions of c-myc, Nanog, Oct3/4, Sox2, and EpCAM were all decreased in pLKO. 1-sh-beta-catenin-CNE2 cells. It was also found that vimentin was downregulated, while E-cadherin was upregulated. Results of MTT and Transwell assays suggested that the proliferation and migration abilities were impaired by silencing of beta-catenin, and more cells were arrested in G1 phase when compared with the control. In vivo study indicated that the tumor growth was markedly suppressed in experimental group. Based on current findings, beta-catenin may function as an essential protein for the maintenance of migration and proliferation abilities of NPC cells, and a complicated network consisting of c-myc, Nanog, Oct3/4, Sox2, EpCAM, E-cadherin, vimentin, and beta-catenin may be involved in the inherent regulation mechanisms.