Aim: The aim of this research is to analyze the profile of Ezh2 expression in superficial urothelial bladder cancer, to investigate its correlation with clinicopathological parameters, as well as to determine the prognostic significance of Ezh2. Introduction: Superficial urothelial bladder cancer, without invasion of muscle layer, is associated with frequent recurrence, and represents significant burden for health care system. Ezh2 is epigenetic regulator with a major role in urothelial oncogenesis. Clinical investigations of Ezh2 inhibitors in treatment of solid cancers have already given encouraging results. Materials and Methods: Tumor samples from 410 patients with superficial bladder cancer (172 pTa, 238 pT1), obtained by transurethral resection, were incorporated in tissue microarrays, and analyzed immunohistochemically to Ezh2 expression. Correlation analysis with clinicopathological parameters was performed using SPSS 18.0. Results: High nuclear expression was found in 33.4% tumors, and it was significantly more frequent in pT1 (46.6%), compared to pTa tumors (15.1%) (p<0.001). Ezh2 expression was associated with high histologic grade, presence of carcinoma in situ, and cancer specific death (p<0.001, respectively). In Kaplan-Mayer survival analysis high Ezh2 expression was significantly associated with poor prognosis and shorter patients survival (p<0.001). There was no significant correlation between Ezh2 and recurrence of the disease, and recurrence free interval (p<0.05). Conclusion: Immunohistochemical expression of transcription repressor Ezh2 in superficial urothelial bladder cancer indicates aggressive behavior of the tumor, and poor prognosis. Ezh2 could be used as pronostic marker in selection of the patients that might require more intense clinical treatment, and as potential target of anticancer therapy.

An increasing number of studies support the concept that cancer stem cells (CSCs) are responsible for initiation, growth and metastasis of malignant neoplasms. CSCs represent the population with tumor initiating potential, and possess the properties of normal stem cells, including the ability of self-renewal and perpetual proliferation, as well as the specific potential of multilineage differentiation, which underlies tumor heterogeneity. The persistence of CSCs has been considered the main culprit for tumor relapse and metastasis, since conventional oncologic protocols do not eradicate CSCs. Development of specific therapeutic strategies targeting CSCs may contribute to significant advance in cancer treatment. The crucial step in CSC targeted therapy development, as well as in subsequent efficacy validation, is the identification of specific stem cell markers, where the role of pathologist is of major significance.