Differential expression and cross-talk of peroxisome proliferator-activated receptor γ and retinoid-X receptor α in urothelial carcinomas of the bladder.

Purpose: the peroxisome proliferator-activated receptor γ (PPARγ), known to play a key role in homeostatic biological pathways, is also implicated in the process of carcinogenesis. Ligands for PPARγ and its heterodimeric partner, retinoid-X receptor (RXR), have exhibited anticancer effects both in vitro and in vivo. Unexpectedly, some studies suggested that PPARγ ligands may stimulate cancer formation. This study aimed to estimate the signaling of PPARγ-RXRα heterodimer in bladder urothelial carcinomas (BUC).

Methods: we studied PPARγ and RXRα expression in specimens obtained from 97 patients with BUC of various grades and stages using immunohistochemistry.

Results: PPARγ expression was significantly downregulated with BUC stage and grade progression, and the dynamics of this phenomenon was significantly influenced by RXRα's level of expression.

Conclusion: the positive association of PPARγ expression in BUC with more differentiated, non-invasive tumors is strengthened by the presence of RXRα. This knowledge could probably be of use in the development of new chemotherapeutic agents.