Aim: To examine peroxisome proliferator-activated receptor gamma (PPARγ) mRNA expression quantitatively in human renal cell carcinoma (RCC) cell lines and RCC tissue, as well as in corresponding normal kidney tissue.
Methods: We examined PPARγ mRNA expression quantitatively in six human RCC cell lines by real-time reverse transcription–polymerase chain reaction. In addition, we evaluated the relationship between cell growth inhibition by PPARγ ligands and the level of PPARγ mRNA expression. We compared the expression of PPARγ mRNA in 47 RCC tissues with that in corresponding normal kidney tissue, and investigated the relationship between clinicopathological features and the level of PPARγ mRNA expression.
Results: Among the six RCC cell lines, five showed decreased PPARγ mRNA expression. There was no relationship between the inhibitory effects of PPARγ ligands and PPARγ mRNA expression levels. Of the tissues from 47 RCC patients, 25 (53%) showed decreased expression of PPARγ mRNA compared to corresponding normal kidney tissue, and one was equivalent to normal tissue. These patients had distant metastasis at diagnosis more frequently than the remaining patients with high expression. There was also a trend for these patients to have a higher stage.
Conclusions: Most RCC cell lines showed decreased expression of PPARγ mRNA. However, the level of PPARγ mRNA expression did not affect cell growth inhibition by PPARγ ligands. More than half of the tissues from RCC patients had low expression of PPARγ mRNA, and such carcinomas might have more aggressive behavior.