Abstract: Objective To explore the role of human short stature homeobox 2 (SHOX2) in regulating the migration, invasion and stemness of human bladder cancer cells. Methods We analyzed SHOX2 gene expression in bladder cancer and adjacent tissues based on TCGA database. Univariate survival analysis of SHOX2 gene expression in TCGA-BLCA data was performed using GEPIA. The probable function of SHOX2 was predicted using GSEA. Human bladder cancer T24 cell models of SHOX2 knockdown or overexpression were assessed for changes in migration and invasion abilities using wound healing assay and Transwell assay, and their cancer stem cell-like characteristics were evaluated using tumorsphere formation assay and colony formation assay. Western blotting was used to detect the expressions of epithelial mesenchymal transition (EMT) markers E-cadherin and vimentin and the TGF-β signaling network component TβR-I in the cells. Results SHOX2 expression was significantly higher in bladder cancer tissues than in the adjacent tissues (P<0.05), especially in paired tissue specimens (P<0.01), and was negatively correlated with the overall survival of the patients (P<0.05). SHOX2 gene expression was correlated positively with EMT-related (P<0.05) and stemness-related gene signatures (P<0.01). In T24 cells, SHOX2 knockdown significantly suppressed cell migration and invasion, which was significantly enhanced by SHOX2 overexpression (P<0.01). The cancer stem cell-like characteristics of T24 cells was repressed by SHOX2 knockdown but significantly enhanced by SHOX2 overexpression (P<0.01). SHOX2 knockdown induced morphological changes of the cells into epithelioid cells, whereas SHOX2 overexpression induced a mesenchymal morphology of the cells. SHOX2 knockdown increased E-cadherin expression and decreased vimentin and TβR-I expression, while SHOX2 overexpression increased the expressions of vimentin and TβR-I in the cells. Conclusion SHOX2 promotes the migration, invasion and stemness of human bladder cancer cells possibly by regulating EMT via the TGF-β signaling pathway

Key words: SHOX2; bladder cancer; migration; invasion; stemness; EMT; TGF-β