Targeting peroxisome proliferator-activated receptor-β/δ in colon cancer: how to aim?

Peroxisome proliferator-activated receptor-β/δ (PPARδ) is a ubiquitously expressed, ligand-activated transcriptional factor that performs diverse critical functions in normal cells (e.g., fatty acid metabolism, obesity, apoptosis, and inflammation). Various studies in humans have found that PPARδ is upregulated in primary colorectal cancers; however, these findings have been challenged by those of other reports. Similarly, various in vitro and in vivo mechanistic pre-clinical models have yielded data demonstrating that PPARδ promotes colonic tumorigenesis, but other models have yielded data that contradicts this notion. Definitive studies are therefore needed to establish the exact role of PPARδ in human colorectal tumorigenesis and to provide a theoretical basis for PPARδ therapeutic targeting.