Promoter methylation status of multidrug resistance 1 (MDR1) gene in noncancerous gastric mucosa correlates with helicobacter pylori infection and gastric cancer occurrence

We investigated the methylation status of multidrug resistance 1 (MDR1) gene promoter in noncancerous gastric mucosa in relation to gastric cancer (GC) occurrence. Methylation of the MDR1 promoter was estimated in 127 GC and 82 non-GC patients. A significant association was found between higher methylation ratio and occurrence of GC. Higher methylation ratio was also associated with occurrence of GC in both Helicobacter pyloripositive and Helicobacter pylorinegative subjects. Higher MR was also associated with Helicobacter pylori infection. Methylation status of MDR1 gene in noncancerous gastric mucosa would be useful for predicting GC occurrence.