Sorting out the functional role(s) of peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) in cell proliferation and cancer

Peroxisome proliferator-activated receptor-beta/delta (PPAR beta/delta) has many beneficial physiological functions ranging from enhancing fatty acid catabolism, improving insulin sensitivity, inhibiting inflammation and increasing oxidative myofibers allowing for improved athletic performance. Thus, given the potential for targeting PPAR beta/delta for the prevention and/or treatment of diseases including diabetes, dyslipidemias, metabolic syndrome and cancer, it is critical to clarify the functional role of PPAR beta/delta in cell proliferation and associated disorders such as cancer. However, there is considerable controversy whether PPAR beta/delta stimulates or inhibits cell proliferation. This review summarizes the literature describing the influence of PPAR beta/delta on cell proliferation, with an emphasis toward dissecting the data that give rise to opposing hypotheses. Suggestions are offered to standardize measurements associated with these studies so that interlaboratory comparisons can be accurately assessed. (C) 2009 Elsevier B.V. All rights reserved.