Cis-acting genetic variation at an E2F1/YY1 response site and putative p53 site is associated with altered allele-specific expression of ERCC5 (XPG) transcript in normal human bronchial epithelium

ERCC5 (XPG) is a key component of the nucleotide excision DNA repair pathway. In two recent case-control studies, we determined that ERCC5 transcript expression pattern in grossly normal human bronchial epithelial cells (NBEC) was different in individuals diagnosed with lung cancer compared with non-lung cancer controls. In this study, we tested the hypothesis that variation at cis-acting sites contributed to observed variation in ERCC5 transcript expression in NBEC. Allele-specific expression (ASE) was measured at transcribed polymorphic site rs1047768 in exon 2 of ERCC5 in NBEC complementary DNA (cDNA) of 22 individuals using allele-specific competitive polymerase chain reaction. ASE at rs1047768 was then assessed for association with allelotype at polymorphic sites rs751402 (E2F1 and YY1 recognition and response site) and rs2296147 (putative P53 recognition site) in the proximal promoter and 5' untranslated region, respectively, of ERCC5. Interindividual variation in recombination between rs751402, rs2296147 and rs1047768 in poly-heterozygotes was controlled for by allele-specific sequencing. Measured rs1047768 T:C allelic ratio was (i) significantly higher in NBEC cDNA compared with genomic DNA controls (P < 0.001) among samples heterozygous at both rs751402 and rs2296147; (ii) less high (P = 0.02) for samples homozygous at rs751402 but heterozygous at rs2296147 and (iii) not significantly different (P = 0.18) for doubly homozygous individuals. Here, we demonstrate that rs751402 A allele and rs2296147 T allele are associated with higher ASE of ERCC5 T allele transcript at rs1047768 in NBEC.