High expression of spindle and kinetochore- associated protein 1 predicts early recurrence and progression of non-muscle invasive bladder cancer

BACKGROUND Spindle and kinetochore-associated protein 1 (SKA1) is a component of SKA, which is essential for proper chromosome segregation. Recently, SKA1 was found to be over-expressed in several types of human cancers. However, reports on the relationship between SKA1 expression and the prognosis of bladder cancer, in particular, are lacking. OBJECTIVES To clarify the clinical significance of SKA1 as a prognostic biomarker for early recurrence and progression of patients with non-muscle invasive bladder cancer (NMIBC). METHODS The differential expression levels of SKA1 of 148 NMIBC tissues were determined by immunohistochemical staining. Quantitative real-time PCR and western blot analysis were further performed to confirm the immunohistochemistry results. Recurrence and progression free interval were assessed by Kaplan-Meier method and differences between groups calculated by log-rank statistics. The prognostic value of SKA1 for early recurrence and progression was analyzed by multivariate Cox proportional hazard regression models. RESULTS SKA1 expression was significantly different in various NMIBC tissues. Kaplan-Meier analysis revealed that patients with high SKA1 expression showed high early recurrence (p< 0.001) and progression (p< 0.05) rates. Although univariate Cox regression analysis revealed that several other factors had an impact on recurrence and progression, upon multivariate analysis, high SKA1expression was the only independent predictor for early recurrence (hazards ratio [HR], 0.246; 95% confidence interval [CI], 0.131-0.461; p= 0.000) and progression (HR, 0.194; 95% CI, 0.052-0.715; p= 0.014). CONCLUSIONS High SKA1 expression is associated with early recurrence and progression in patients with NMIBC, indicating SKA1 may serve as a promising prognostic biomarker for this disease.