Supplementary Material for: High MT2A Expression Predicts Worse Prognosis in Patients with Urothelial Carcinoma

Introduction: Dysregulation of metal ion homeostasis is associated with urothelial carcinogenesis. From a published urinary bladder urothelial carcinoma (UBUC) transcriptome, we identified metallothionein 2A (MT2A) as the most significantly upregulated gene implicated in cancer progression among metal ion binding-related genes. Therefore, we analyzed the association between MT2A expression and clinical significance in our well-characterized cohort of patients with upper tract urothelial carcinoma (UTUC) and UBUC. Methods: We retrospectively reviewed the clinicopathological characteristics of 295 and 340 patients with UBUC and UTUC, respectively. MT2A expression was assessed using real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry. We further correlated MT2A expression with clinicopathological factors, disease specific survival (DSS) and metastasis-free survival (MFS) using the Pearson's chi-square test, Kaplan-Meier analysis, and multivariate Cox proportional hazards model. Results: High MT2A expression was significantly associated with aggressive pathological features including high tumor stage, lymph node metastasis, high tumor grade, vascular invasion, and perineural invasion. In the Kaplan-Meier analysis, high MT2A expression was significantly correlated with poor DSS (P < 0.0001) and MFS (P < 0.0001); in the multivariate analysis, it was an independent predictor of CSS (P < 0.001) and MFS (P = 0.001). Gene co-expression analysis demonstrated that MT2A overexpression promotes UC progression through complement activation. Conclusion: High MT2A expression correlated with aggressive UC features and was an independent predictor of cancer metastasis and patient survival, suggesting its role in risk stratification and decision-making in patients with UTUC and UBUC.