Methylation of CYP1A1 and VKORC1 promoter associated with stable dosage of warfarin in Chinese patients

Promises and challenges in pharmacoepigenetics

Pharmacogenetics, the study of how interindividual genetic differences affect drug response, does not explain all observed heritable variance in drug response. Epigenetic mechanisms, such as DNA methylation, and histone acetylation may account for some of the unexplained variances. Epigenetic mechanisms modulate gene expression and can be suitable drug targets and can impact the action of nonepigenetic drugs. Pharmacoepigenetics is the field that studies the relationship between epigenetic variability and drug response. Much of this research focuses on compounds targeting epigenetic mechanisms, called epigenetic drugs, which are used to treat cancers, immune disorders, and other diseases. Several studies also suggest an epigenetic role in classical drug response; however, we know little about this area. The amount of information correlating epigenetic biomarkers to molecular datasets has recently expanded due to technological advances, and novel computational approaches have emerged to better identify and predict epigenetic interactions. We propose that the relationship between epigenetics and classical drug response may be examined using data already available by (1) finding regions of epigenetic variance, (2) pinpointing key epigenetic biomarkers within these regions, and (3) mapping these biomarkers to a drug-response phenotype. This approach expands on existing knowledge to generate putative pharmacoepigenetic relationships, which can be tested experimentally. Epigenetic modifications are involved in disease and drug response. Therefore, understanding how epigenetic drivers impact the response to classical drugs is important for improving drug design and administration to better treat disease.

Impact of DNA methylation on ADME gene expression, drug disposition and efficacy

Interindividual differences in drug response have always existed in clinical treatment. Genes involved in drug absorption, distribution, metabolism, and excretion (ADME) play an important role in the process of pharmacokinetics. The effects of genetic polymorphism and nuclear receptors on the expression of drug metabolism enzymes and transporters can only explain some individual differences in clinical treatment. Several key ADME genes have been demonstrated to be regulated by epigenetic mechanisms that can potentially affect interindividual variability in medical treatment. Emerging studies have focused on the importance of DNA methylation for ADME gene expression and for drug response. Among them, the most studied is anti-tumor drugs, and followed by anti-tuberculous and anti-platelet drugs. Therefore, we provide an epigenetics perspective on variability in drug response. The review summarizes the correlation between ADME gene expression and DNA methylation, including the exact methylation locations, and focuses on the corresponding drug disposition and effects to illuminate interindividual differences in clinical medication.