RXRgamma and PPARgamma ligands in combination to inhibit proliferation and invasiveness in colon cancer cells.

Nuclear retinoid X receptors (RXRs) and peroxisome proliferator-activated receptors (PPARs are potential candidates as drug target for cancer prevention and treatment. We investigated if the rexinoid 6-OH-11-O-hydroxyphenantrene (IIF) potentiates the antitumoral properties of PPARgamma ligands as ciglitazone and pioglitazone, on two colon cancer cell lines: HCA-7 and HCT-116. Drugs inhibited cell growth and induced apoptosis synergistically. The combination resulted in a decrease of cyclooxigenase-2, metalloproteinases-2 and -9 expression level and activity while PPARgamma, RXRgamma and tissue inhibitors of metalloproteinase-1 and -2 expression were increased. Finally, IIF potentiated PPAR transcriptional activity by enhancement of peroxisome proliferator response elements transactivation.