The Dephosphorylation of MCM2 at Serine27 Site Attenuates Ovarian Cancer Metastasis via Regulating Wnt/β-Catenin Signaling Pathway

Abstract

Background: Protein phosphorylation plays a pivotal role in cancer metastasis. We first clarified the relation of Serine 27(Ser27) site phosphorylation of minichromosome maintenance protein 2 (pMCM2- Ser27) to tumor metastasis and here aimed to clear the clinical significance of the site phosphorylation in ovarian cancer and the role of the site phosphorylation in the process of ovarian cancer (OC) metastasis. Methods: Immunohistochemistry (IHC) was undertaken to investigate pMCM2- Ser27 expression in ovarian cancer tissues and normal adjacent tissues. Wound-healing and Transwell assays were used to uncover the relationship between the dephosphorylation of MCM2 at Ser27 site (depMCM2-Ser27) and cell migration, invasion. Lung metastasis model (n=5) was established to detect whether depMCM2-Ser27 affects OC cells metastasis in vivo. SB216763 was used to inactivate glycogen synthase kinase-3β (GSK3β). Western blot, Immunofluorescence (IF), GST pull-down, Coimmunoprecipitation (CoIP) and Immunoprecipitation (IP) analyses were conducted to explore underlying mechanism of depMCM2-Ser27 in metastasis suppression. Licl, Wnt3α, SKL2001 and TOP/FOP assays were used to investigate the correlation of depMCM2-Ser27 to Wnt/β-catenin pathway. Findings: depMCM2-Ser27 lead to a marked attenuation in OC cells metastasis in vivo and vitro. In addition, GSK3β could interact with MCM2 and phosphorylate MCM2 at Ser27 site. depMCM2-Ser27 augmented the interaction of GSK3β with β-catenin and decreased β-catenin stability, accompanied by the up-regulation of β-catenin phosphorylation and ubiquitination, the attenuation of β-catenin nuclear translocation and the inactivation of Wnt/β-catenin pathway. depMCM2-Ser27 suppressed OC cells metastasis by inactivating Wnt/β-catenin pathway. Interpretation: These findings elucidate the vital role of pMCM2-Ser27 in the Wnt/β-catenin pathway mediated-metastasis process and provides insights for the development of novel therapies to treat advanced OC. Funding Statement: This work was supported by the National Natural Science Foundation of China (81470367). Declaration of Interests: The authors do not have a commercial or other association with pharmaceutical companies or other parties that might pose a conflict of interest. Ethics Approval Statement: All laboratory animals operations were conducted in accordance with the rules of the Laboratory Animal Ethics Committee (Number of the using of Laboratory Animal: SCXK (jing) 2014-004). The research was approved by the Ethics Committee of Dalian Medical University.