Functional analysis of a lung cancer risk haplotype in the IL1B gene regulatory region

Interleukin-1β (IL-1β), encoded by the IL1B gene, is a cytokine important in regulation of the inflammatory response. Elevated levels of IL1B expression have been associated with risk of gastric and lung cancer. We previously reported that a certain haplotype containing four single-nucleotide polymorphisms (SNPs) (-3893G, -1464G, -511C and -31T; GGCT) in the IL1B gene regulatory region was associated with lung cancer risk and increased expression of the IL1B gene in the lung. In the present study, we have cloned the two haplotypes that were either protective (ACTC) or increasing lung cancer risk (GGCT) in a luciferase reporter vector system. We also cloned the IL1B -3893 and -1464 SNPs that were found to be associated with risk of lung cancer. The haplotype associated with lung cancer risk showed higher transcriptional activity in the human lung epithelial A549 cell line in vitro. We also found that the IL1B -1464C allele increased transcriptional activity compared with the -1464G allele in the tumor necrosis factor α-stimulated cells, as well as specific transcription factor binding patterns to the IL1B -1464C allele. Interestingly, in vitro results showed a similar expression pattern as observed in the normal lung tissues of lung cancer patients reported earlier.