Pregnane X Receptor and its Potential Role in Drug Resistance in Cancer Treatment

Multi-drug resistance (MDR) is a significant barrier to effective chemotherapy of cancer. The induction of drug metabolizing enzymes (DMEs) and efflux transporters has been regarded as one of the major mechanisms of drug resistance. As a master transcription factor of DMEs and efflux transporters, pregnane X receptor (PXR), an orphan nuclear receptor known for its activation by structurally diverse compounds, is expressed in some cancer cells and tissues, and is implicated as a novel master regulator of MDR in cancers. This review describes recent publications and patents on the mechanism of PXR transcription, the expression of PXR in cancers, and its potential roles in cancer MDR. We also discuss the recent patents published to overcome PXR-mediated MDR and other potential roles of PXR in cancers.