A study has demonstrated for the first time that the levels of DNA methylation of the promoter regions of the genes encoding IL-1β, IL-6 and IL-8 are increased in human non-small-cell lung cancer (NSCLC) cells. High DNA methylation levels of these gene promoters were associated with reduced mRNA levels in lung cancer cells, whereas the mRNA levels of these genes were higher in normal bronchial epithelial cells or adjacent nontumourous tissues. This inverse relationship was strongest for IL-1β, in which hypermethylation was associated with silencing of IL1B in cancer cells.