Peroxisome Proliferator-Activated Receptor [gamma] and PGC-1[alpha] in Cancer: Dual Actions as Tumor Promoter and Suppressor

Peroxisome proliferator-activated receptor y (PPAR[gamma]) is part of a nuclear receptor superfamily that regulates gene expression involved in cell differentiation, proliferation, immune/inflammation response, and lipid metabolism. PPAR[gamma] coactivator-1[alpha] (PGC1[alpha]), initially identified as a PPAR[gamma]-interacting protein, is an important regulator of diverse metabolic pathways, such as oxidative metabolism and energy homeostasis. The role of PGC-1[alpha] in diabetes, neurodegeneration, and cardiovascular disease is particularly well known. PGC-1[alpha] is also now known to play important roles in cancer, independent of the role of PPAR[gamma] in cancer. Though many researchers have studied the expression and clinical implications of PPAR[gamma] and PGC-1[alpha] in cancer, there are still many controversies about the role of PPAR[gamma] and PGC-1[alpha] in cancer. This review examines and summarizes some recent data on the role and action mechanisms of PPAR[gamma] and PGC-1[alpha] in cancer, respectively, particularly the recent progress in understanding the role of PPAR[gamma] in several cancers since our review was published in 2012.