Genetic polymorphisms in tumor necrosis factor alpha and interleukin-10 are associated with an increased risk of cervical cancer

Abstract

Most cases of cervical cancer are the result of infection with specific high-risk types of human papillomavirus (HPV). Investigating the genetic basis of the host immune response, particularly cytokine function, could help further characterize the progression of cervical HPV infection into neoplasia. Prior studies have demonstrated a correlation between genetic variants of tumor necrosis factor alpha (TNF-α, TNF gene) and/or interleukin-10 (IL-10, IL10 gene) and cervical cancer susceptibility. However, some of the results have been contradictory. We sought to resolve these discrepancies by carrying out our study in a large cohort of Chinese women. In order to assess the association of TNF and IL10 genotypes with cervical cancer susceptibility, the polymorphisms in TNF (-238 G/A, -308 G/A) and IL10 (-592 C/A, -819 C/T, -1082 A/G) were genotyped and odds ratios for the genotype and allele frequencies between cervical cancer patients and healthy controls were calculated. Also, the functional relevance of these polymorphisms was evaluated using enzyme-linked immunosorbent assays (ELISAs) and in vitro lymphocyte proliferation assays. The TNF-238 AA genotype frequency was lower in patients than in controls (p < 0.05). TNF-308 AA, IL10-592 CA/AA, and IL10-819 CC/CT genotype frequencies were higher in cervical cancer patients than in controls (p < 0.05). The frequency of the TNF-238 A allele was significantly lower in patients, while the frequency of the -308 A allele was significantly higher (p < 0.05). No significant differences between patients and controls were found in the genotype or allele frequencies of IL10-1082 A/G (p > 0.05). Furthermore, the combinations of TNF-238 GA or GG and IL10-592 CC; TNF-238 GA or GG and IL10-592 CA or AA; TNF-308 AA and IL10-592 CC; and TNF-308 AA and IL10-592 CA or AA in cervical cancer patients were statistically significant (p < 0.0167). Upon stimulation with PHA, peripheral blood mononuclear cells (PBMCs) with the TNF-308AA genotype exhibited significantly higher proliferation rates, elevated IL-4, TGF-β levels, and lower IL-2 levels (p < 0.05). For IL10-592C/A, the AA and CA genotypes were significantly associated with higher proliferation rates, elevated IL-4 and IL-10 levels (p < 0.05). We also found that for TNF-308 G/A or IL10-592 C/A variants, the combination of TNF-308 GG or GA with IL10 CA or AA had an association with the severity of cervical cancer. Taken together, these results suggest that TNF-308 AA and IL10-592 CA/AA genotypes may increase susceptibility to cervical cancer by altering the immune response of an individual.

Keywords: Cervical cancer; Gene polymorphism; IL-10; Tumor necrosis factor alpha.