Screening of 3’ UTR PXR Polymorphisms in South Indian Breast Cancer Patients and its Potential Role in Pharmacogenomics

Human Pregnane X Receptor (also called NR1I2), a member of orphan nuclear receptor superfamily, maps to chromosome 3q11-13 with ten exons coding for 434 amino acids (Zhang et al., 2001). PXR is a xenobiotic sensor and acts as a transcription factor of drug metabolizing enzymes (DMEs) and drug transporters. It can potentially affect the efficacy of chemotherapeutic drugs given during cancer treatment by transcriptionally regulating genes like P-glycoprotein, CYP3A, CYP2B6, UGT1A1, ABCB1 multidrug resistance proteins and glutathione S-transferases which accelerate the metabolism and elimination of chemotherapeutic agents like cyclophosphamide, tamoxifen and taxol (Honkakoski et al., 2000). PXR predominantly expressed in liver and intestine and to a lesser extent in other organs like