Association Of β-transducin Repeat-containing Protein (β-TrCP) Genetic Polymorphisms With Hepatocellular Carcinoma Susceptibility And Its Functional Analysis

Objective: To investigate the association and the molecular mechanism of genetic polymorphisms in 3′UTR ofβ-TrCP with hepatocellular carcinoma (HCC) susceptibility.Methods: (1) Using bioinformatic tools to screen genetic polymorphism in 3′UTR ofβ-TrCP which residing in the microRNAs binding sites and its minimum allele frequency (MAF) is greater than 0.3; (2) Based on prediction results, we performed a case-control study to detect association between selected polymorphisms and HCC susceptibility; (3) For positive polymorphism, real-time PCR was applied to check theβ-TrCP mRNA levels in HCC tissue samples with different genotype; (4) For functional site, bioinformatics'methods, such as MiRanda and TargetScan, were carried out to investigate the preliminary molecular mechanism of the site, which may affect the hybridization of putative microRNA and the target in theβ-TrCP gene.Results:(1) A polymorphism (rs16405) was identified which residing in the microRNAs binding sites and MAF>0.3. Genotyping results showed that frequencies of insertion and deletion alleles were 0.379 and 0.621 in case group, 0.305 and 0695 in control group;(2) After adjustment for sex, age, smoking status, drinking status and HBV infection, we found that rs16405 was associated with the risk of HCC significantly. Carriage of the deletion allele was associated with a greatly decreased risk of developing the disease (OR 0.72 [95% C.I. 0.56-0.92], P=0.0067). Further analysis with rs16405 genotypes showed that homozygote DEL/DEL have a reduced risk of HCC compared with its homozygote INS/INS and heterozygote INS/DEL;(3) Real-time PCR results showed that theβ-TrCP mRNA levels of three genotypic groups were significantly different (P<0.05). HCC tumor tissues with homozygous INS/INS had the highest level ofβTrCP, which are 3.99 and 7.04-fold higher than heterozygous INS/DEL and homozygous DEL/DEL, respectively;(4) Based on bioinformatics prediction, we found that the risk allele for rs16405 disrupts a binding site for microRNA-920, which would negatively regulateβTrCP.Conclusion: (1) A case-control study showed that rs16405 polymorphism is associated with the HCC susceptibility; (2) Our in vivo experiments demonstrated that the polymorphism is associated withβTrCP mRNA levels; (3) Based on bioinformatics prediction, We propose a miRNA-920 mediatedβTrCP regulation model depending on rs16405 genotype, considerading the association ofβTrCP and HCC, which indicating that this polymorphism is possibly involved in the pathogenesis of HCC.