Immunohistochemical analysis of the role and relationship between Notch‐1 and Oct‐4 expression in urinary bladder carcinoma

Most tumors contain a minor population of cancer stem cells that are responsible for tumor heterogeneity, resistance to therapy and recurrence. Oct‐4 is a transcription factor responsible for self‐renewal of stem cells, whereas the Notch family of receptors and ligands may play a pivotal role in the regulation of stem cell maintenance and differentiation. This study aimed at an evaluation of Oct‐4 and Notch‐1 expression in both carcinoma and stromal cells of 83 cases of primary bladder carcinoma and to study the relationship between them. Notch‐1 was expressed in carcinoma and stromal cells of all malignant cases, where expression in both cell types was correlated with parameters indicating differentiation, such as low grade (p < 0.05) and less proliferation (p < 0.05). However, Notch‐1 expression in stromal cells was associated with nodal metastasis (p = 0.016) and advanced stage (p = 0.030). 56.6 and 75.9% of carcinoma and stromal cells of malignant cases showed Oct‐4 expression, respectively. Oct‐4 expression in carcinoma cells or stromal cells was associated with aggressive features of bladder carcinoma, such as poor differentiation (p = 0.001), high proliferation (p < 0.001, 0.030), and liability for recurrence (p = 0.010, p < 0.001). There was an inverse relationship between Notch‐1 and Oct‐4 expression in carcinoma cells (p = 0.002), but stromal expression of Notch‐1 was found to be associated with a nuclear pattern of Oct‐4 expression in carcinoma cells (p = 0.030). Oct‐4 as a stem cell marker is expressed in carcinoma cells and in stromal cells of bladder carcinoma, where they may cooperate in the progression of bladder carcinoma by acquiring aggressive features, such as a liability for recurrence and dissemination. Notch‐1 is also expressed in both carcinoma cells and stromal cells of bladder carcinoma. Although they could share in enhancing differentiation, stromal expression of Notch‐1 may have a bad impact, possibly through up‐regulation of the active nuclear form of Oct‐4 in carcinoma cells.