An indel polymorphism in the 3' untranslated region of HMGB1 confers risk for hepatocellular carcinoma by regulating HMGB1 transcriptional activity in a Chinese population.

The present study aimed to assess the association of rs34000982 polymorphism located in the 3'untranslated region (3'UTR) of high mobility group box 1 (HMGB1) gene and the risk of hepatocellular carcinoma (HCC), and further to explore the underlying mechanism. Genomic DNA was extracted from peripheral blood of 320 patients with HCC and 360 matched controls. Rs34000982 polymorphism was genotyped by a polymerase chain reaction-polyacrylamide gel electrophoresis assay. The genotype-phenotype association of HMGB1 mRNA and protein expression in HCC tissues with different genotypes was detected by quantitative (q) PCR assay and western blot. Vectors containing the insertion (ins)/ins or deletion (del)/del genotype of the rs34000982 polymorphism were constructed and the HMGB1 transcriptional activity affected by the rs34000982 polymorphism was detected by the luciferase assay. It was identified that the ins/ins genotype of rs34000982 significantly increased the risk of HCC compared with the del/del genotype. Further the qPCR results demonstrated that the HMGB1 mRNA expression level in HCC tissues with ins/ins genotype was 2.24 times that of HCC tissues with ins/del and del/del genotypes and there was a similar trend at protein level. In addition, the insertion allele of rs34000982 disturbed the binding of miR-636 with the 3'UTR of HMGB1, thereby increasing HMGB1 transcriptional activity in vitro. These data suggest that the rs34000982 polymorphism may contribute to HCC susceptibility, in full or at least partially through the effect on HMGB1 transcriptional activity by disturbing the binding of miR-636 with the 3'UTR of HMGB1.