Abstract: Objective To investigate the role of solute carrier family 12 member A8 (SLC12A8) in regulation of biological behaviors of bladder cancer and the mechanism mediating its effect. Methods The TCGA database was used to analyze SLC12A8 expression in bladder cancer and is correlation with prognosis and clinicopathological characteristics of the patients. In different bladder cancer cell lines, the effects of transient transfection with SLC12A8 siRNA on cell proliferation, invasion and migration ability were examined using CCK-8 assay, Transwell assay and scratch experiment. Gene set enrichment analysis (GSEA) was carried out to analyze pathway enrichment. The correlation of SLC12A8 with the expressions of epithelial-mesenchymal transition (EMT) markers was analyzed using Western blotting. The effect of colivelin on biological behaviors of the cells with SLC12A8 knockdown was assessed using CCK-8 and Transwell assays. Results SLC12A8 was highly expressed in bladder cancer (P<0.05) and associated with a poor prognosis and advanced pathological stages of the patients (P<0.05), and could serve as an independent prognostic factor. The bladder cancer cell lines with SLC12A8 knockdown showed significantly attenuated proliferation, invasion and migration capacities (P<0.05). GSEA identified significant gene enrichment in the JAK/STAT signaling pathway (P=0.008). Correlation analysis showed that SLC12A8 expression was negatively correlated with E-cadherin expression (r=- 0.183, P<0.001) but positively with N-cadherin (r=0.302, P<0.001) and vimentin (r=0.342, P<0.001) expressions. The bladder cancer cells with SLC12A8 knockdown showed significantly decreased expressions of p-Jak2, p-Stat3, N-cadherin and vimentin proteins with an increased expression of E-cadherin. Treatment with colivelin effectively enhanced proliferation, invasion and migration capacities of the bladder cancer cells with SLC12A8 knockdown (P<0.05). Conclusion SLC12A8 promotes bladder cancer progression by activating the JAK/STAT signaling pathway and its high expression is closely associated with a poor prognosis of the patients.

Key words: SLC12A8; bladder cancer; JAK/STAT; proliferation; epithelial-mesenchymal transition