Deregulation of SLIT2-Mediated Cdc42 Activity Is Associated with Esophageal Cancer Metastasis and Poor Prognosis
Introduction: SLIT2, a secreted protein, has been found to inac- tivate Cdc42 GTPase to modulate neural cell migration. However, alteration of SLIT2-mediated Cdc42 in terms of migration regulation remains undefined in esophageal squamous cell carcinoma (ESCC). Methods: We report here in ESCC cell, animal, and clinical models that SLIT2 acts as a migration suppressor and serves as a prognostic biomarker. Results: The immunohistochemistry data indicated that 31.8% (49 of 154) of tumors from ESCC patients showed low expres- sion of SLIT2 protein which correlated with poor overall survival and disease-free survival. DNA methylation analysis suggested that promoter hypermethylation is responsible for low expres- sion of SLIT2 in ESCC. Knockdown of SLIT2 increased ESCC cell migration, while SLIT2 stable overexpression reduced cell migration. ESCC cells treated with conditioned media from cells overexpressing SLIT2 also suppressed cell migration. Importantly, silencing of SLIT2 decreased the complex formation, and thus induced Cdc42 activity and promoted membrane localization of focal adhesion kinase and Paxillin. Anti-metastatic effect of SLIT2 was confirmed in an experimental metastasis model of SLIT2 knockdown ESCC cells. Conclusion: Our results provide novel evidence that low expression of SLIT2 correlates with poor prognosis and promotes metastasis in ESCC, which may be regulated by the Cdc42-mediated pathways.