Peroxisome proliferator-activated receptor gamma (PPAR gamma) plays an important role in the differentiation of intestinal cells and tissues. Our previous reports indicate that PPAR gamma is expressed at considerable levels in human colon cancer cells. This suggests that PPAR gamma expression may be an important factor for cell growth regulation in colon cancer. In this study, we investigated PPAR gamma expression in 4 human colon cancer cell lines, HT-29, LOVO, DLD-1, and Caco-2. Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that the relative levels of PPAR gamma mRNA and protein in these cells were in the order HT-29 > LOVO > Caco-2 > DLD-1. We also found that PPAR gamma overexpression promoted cell growth inhibition in PPAR gamma lower-expressing cell lines (Caco-2 and DLD-1), but not in higher-expressing cells (HT-29 and LOVO). We observed a correlation between the level of PPAR gamma expression and the cells' sensitivity for proliferation. (C) 2012 Elsevier Inc. All rights reserved.