Peroxisome Proliferator-Activated Receptor γ and PGC-1 α in Cancer: Dual Actions as Tumor Promoter and Suppressor.

Peroxisome proliferator-activated receptor γ (PPAR γ ) is part of a nuclear receptor superfamily that regulates gene expression involved in cell differentiation, proliferation, immune/inflammation response, and lipid metabolism. PPAR γ coactivator-1 α (PGC-1 α ), initially identified as a PPAR γ -interacting protein, is an important regulator of diverse metabolic pathways, such as oxidative metabolism and energy homeostasis. The role of PGC-1 α in diabetes, neurodegeneration, and cardiovascular disease is particularly well known. PGC-1 α is also now known to play important roles in cancer, independent of the role of PPAR γ in cancer. Though many researchers have studied the expression and clinical implications of PPAR γ and PGC-1 α in cancer, there are still many controversies about the role of PPAR γ and PGC-1 α in cancer. This review examines and summarizes some recent data on the role and action mechanisms of PPAR γ and PGC-1 α in cancer, respectively, particularly the recent progress in understanding the role of PPAR γ in several cancers since our review was published in 2012.