Overexpression of the PPAR-gamma protein in primary Ta/T1 non-muscle-invasive urothelial carcinoma

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a well-known nuclear receptor that is activated in the nucleus to regulate several transcription factors. Its expression patterns have been examined in various types of cancer. The present study investigated the expression patterns of PPAR-gamma in non-muscle-invasive urothelial carcinoma. The expression rates of PPAR-gamma, p53 and Ki-67 were compared to determine whether PPAR-gamma may be considered as an immunobiomarker for bladder cancer. The intensity and extent of PPAR-gamma expression were evaluated in 79 cases of non-muscle-invasive urothelial carcinoma (30 cases of papillary carcinoma low-grade, 30 cases of high-grade and 19 cases of carcinoma in situ) and 30 non-malignant cases. The nuclear overexpression of PPAR-gamma was frequently observed in non-muscle-invasive urothelial carcinoma (63/79 cases) but was rarely detected in non-malignant cases (2/30 cases). The histological proliferation types of non-muscle-invasive urothelial carcinoma revealed that PPAR-gamma was more frequently overexpressed in papillary carcinoma (54/60 cases) than in carcinoma in situ (9/19 cases). Immunohistochemical staining demonstrated that PPAR-gamma was more useful as an immunobiomarker than p53 or Ki-67 (diagnostic odds ratios; 55.13, 16.82 and 11.13, respectively). In summary, this study demonstrated that the expression patterns of PPAR-gamma were associated with histological proliferation type and that PPAR-gamma was expressed in the nuclei of papillary carcinoma cells. These findings suggested that immunohistochemical staining for PPAR-gamma may be used to comprehensively detect non-muscle-invasive urothelial carcinoma.