DNA methylation of the POMC gene promoter is associated with craving in alcohol dependence

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been implicated in the pathogenesis of addictive behaviour and especially in alcohol craving. The pro-opiomelanocortin gene (POMC), encoding a 241 amino acids stretching polypeptide hormone precursor, plays an important role in the regulation of the HPA, and is prone to epigenetic regulation due to promoter-related DNA methylation. Aim of the present study therefore was to investigate possible differences in promoter-related DNA methylation in patients suffering from alcohol dependence compared to healthy controls. We analysed the DNA methylation of the 5' promoter of the POMC gene that is embedded in a CpG island using bisulfite sequencing in 145 alcohol-dependent patients and 37 healthy controls taken from the Franconian Alcoholism Research Studies. We found only marginal, hence significant differences at single CpG sites between patients and controls. We identified a cluster of CpGs showing a significant association with alcohol craving in the patients group. These results implicate that epigenetic changes possibly due to alcohol intake may contribute to craving via promoting HPA-axis dysfunction. Further studies should more closely investigate the impact of these changes on the several derivatives of the POMC gene.