Peroxisome proliferator-activated receptors (PPARs) and associated transcription factors in colon cancer: reduced expression of PPARγ-coactivator 1 (PGC-1)

Peroxisome proliferator-activated receptors (PPARs) α,β/δ and γ are fatty acid sensitive transcription factors that have been implicated in colorectal cancer. To better understand their role, we studied the expression levels of all PPAR-isoforms and transcriptional partners such as the retinoid X receptor α (RXRα) and PPARγ-coactivator-1 (PGC-1) by means of real-time PCR in 17 patients with colon cancer. While a heterogeneous pattern was observed for the expression level of the PPAR-isoforms α,β/δ and γ, the coactivator PGC-1 was significantly decreased in 15 of 17 tumors. Taken together our data suggest that the transcriptional activity of PPARγ may not only be decreased by mutation but also by downregulation of the coactivator PGC-1 of PPARγ.