Activation of PPARgamma leads to inhibition of anchorage-independent growth of human colorectal cancer cells

Abstract

Background & aims: Peroxisomal proliferator-activated receptor gamma (PPARgamma) is a nuclear hormone receptor that provides a direct link between fatty acid metabolism and control of gene transcription. The objective of this study was to determine the biological effect(s) of PPARgamma activation in colorectal carcinoma cells.

Methods: PPARgamma expression and activity were measured in 4 human colon cancer cell lines using reverse-transcription polymerase chain reaction, immunoprecipitation and immunoblotting, and transient reporter gene assays. The effects of activated PPARgamma in these cell lines were assessed in cellular proliferation and anchorage-independent growth assays. Flow cytometry was used to determine the effects of PPARgamma activation on progression through the cell cycle.

Results: PPARgamma was expressed in all 4 colon cancer cell lines examined and was transcriptionally functional in 3 of the 4. Treatment of these cells with a selective PPARgamma activator (BRL 49653) resulted in inhibition of anchorage-independent growth. The degree of growth inhibition correlated with the level of functional PPARgamma present. Finally, activation of PPARgamma resulted in G1 cell cycle arrest.

Conclusions: Activation of the PPARgamma pathway in colon cancer cells has potent antiproliferative effects, suggesting that this nuclear hormone receptor may provide a novel target for prevention and treatment of colorectal cancer in humans.