Peroxisome-proliferator-activated receptors (PPARs) are ligand-activated nuclear 
receptors that exert in the liver a transcriptional activity regulating a whole 
spectrum of physiological functions, including cholesterol and bile acid 
homeostasis, lipid/glucose metabolism, inflammatory responses, regenerative 
mechanisms, and cell differentiation/proliferation. Dysregulations of the 
expression, or activity, of specific PPAR isoforms in the liver are therefore 
believed to represent critical mechanisms contributing to the development of 
hepatic metabolic diseases, disorders induced by hepatic viral infections, and 
hepatocellular adenoma and carcinoma. In this regard, specific PPAR agonists 
have proven to be useful to treat these metabolic diseases, but for cancer 
therapies, the use of PPAR agonists is still debated. Interestingly, in addition 
to previously described mechanisms regulating PPARs expression and activity, 
microRNAs are emerging as new important regulators of PPAR expression and 
activity in pathophysiological conditions and therefore may represent future 
therapeutic targets to treat hepatic metabolic disorders and cancers. Here, we 
reviewed the current knowledge about the general roles of the different PPAR 
isoforms in common chronic metabolic and infectious liver diseases, as well as 
in the development of hepatic cancers. Recent works highlighting the regulation 
of PPARs by microRNAs in both physiological and pathological situations with a 
focus on the liver are also discussed.