Peroxisome proliferators and cellular signaling pathways. A review

In a variety of biological systems, the cellular response to an extracellular stimulus is mediated by a complex cascade of biochemical signals transduced from the cellular membrane to the specific part(s) of the cell where the response(s) occur(s). The signal transduction pathways do form a matrix of several reactions involving increased intracellular free Ca2+ levels, activation of Na+/H+ exchange, stimulation of phosphatidylinositol turnover, activation of protein kinase C and increased transcription of several cellular proto-oncogenes. Each of them is subject to modulation at many levels, and is also susceptible to deregulation during chemically-induced carcinogenesis. It is the aim of this short review to give an insight into the complexity of this system which may mediate the effects induced in hepatocytes by peroxisome proliferators or may, upon chronic exposure, be altered by some of them.