The Involvement of PPARs in the Peculiar Energetic Metabolism of Tumor Cells

Energy homeostasis is crucial for cell fate since all cellular activities are strongly dependent on the balance between catabolic and anabolic pathways. In particular, metabolic and energetic modulation has been reported in cancer cells long time ago, but have been neglected for a long time. Instead, during the past 20 years a recovery of the study of cancer metabolism has led to better consider metabolic alterations in tumors. Cancer cells must adapt their metabolism to meet the energetic and biosynthetic demands that accompany rapid growth of the primary tumor and colonization of distinct metastatic sites. They are largely dependent on aerobic glycolysis for their energy production and also are associated with increased fatty acid synthesis and increased rates of glutamine utilization. Emerging evidence has shown that therapeutic resistance to cancer treatment may arise due to deregulation in glucose metabolism, fatty acid synthesis, and glutamine utilization. Cancer cells exhibit a series of metabolic alterations induced by mutations leading to gain-of-function of oncogenes and loss-of-function of tumor suppressor genes that include increased glucose consumption, reduced mitochondrial respiration, increased reactive oxygen species generation and cell death resistance, all of which responsible for cancer progression. Cholesterol metabolism is also altered in cancer cells and supports uncontrolled cell growth. In this context, we review the roles of PPARs transcription factors, master regulators of cellular energetic metabolism, in the control and deregulation of energetic homeostasis observed in cancer. We highlight the different contribution of the different PPAR isotypes in different cancers and the differential control of their transcription in the different cancer cells.