Association between interleukin-21 gene polymorphisms (rs12508721) and HBV-related hepatocellular carcinoma

Interleukin-21 (IL-21), as a multifunctional cytokine, plays an important role in many diseases, such as cancer, inflammatory and autoimmune diseases. We aimed to investigate the relationship between polymorphisms of IL-21 gene and susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in a Chinese population. Studied subjects were divided into three groups: 100 patients with HBV-related HCC, 115 patients with chronic HBV infection and 127 healthy controls. Genomic DNA was isolated from peripheral blood, and the polymerase chain reaction-ligase detection reaction (PCR-LDR) method was used to genotype the SNPs (rs2221903, rs907715 and rs12508721) within IL-21 gene. Our results showed that IL-21 polymorphisms were associated with the risk of HCC and chronic HBV infection when compared with healthy controls. The rs2221903A/G AG genotype was associated with a higher risk of chronic HBV infection when compared with healthy controls [AG versus AA + GG, P = 0.036, OR = 1.898, 95%CI = 1.038-3.471]. The rs12508721C/T TT genotype was related with a lower risk of chronic HBV infection and HBV-related HCC than in healthy controls [TT versus CT + CC, P = 0.026, OR = 0.451, 95%CI = 0.221-0.920; P = 0.049, OR = 0.482, 95%CI = 0.231-1.005]. No significant difference in the genotype and allele distrubutions of rs907715G/A SNP was observed in the HBV-related HCC group, chronic HBV-infected group and the healthy control group when compared to each other. Our findings suggest that the rs12508721T/C and rs2221903A/G polymorphisms of IL-21 gene are associated with the susceptibility of HBV-related HCC and chronic HBV infection. The genetic variant may in fact cause protection against the HBV-related HCC. However, the function in these SNPs of IL-21 gene needs to clarify the mechanisms involved in the pathogenesis of HBV-related HCC further.