Aim: Inflammation plays a lead role in the tumor microenvironment and promotes metastasis. Single-nucleotide polymorphism (SNP) in the tumor necrosis factor (TNF) gene locus may alter the expression of genes and proteins. The objective of the study is to find the distribution of genetic polymorphism in the sites of TNF-α -308G>A and TNF- β +252A>G in breast cancer and evaluate polymorphism effects on plasma levels.
Materials and methods: The study group consisted of 109 invasive ductal primary breast cancer patients and 75 age-matched healthy female controls. Plasma cytokine concentrations were measured by the MILLIPLEX® MAP Human Cytokine/Chemokine Panel magnetic bead kits. The genotyping procedure for SNP included allele-specific polymerase chain reaction for TNFα and restriction fragment length polymorphism for TNFβ.
Results: Odds ratio with 95% confidence interval showed that these polymorphisms were not a causative risk factor, and both polymorphisms were consistent with Hardy-Weinberg equilibrium. Plasma TNFα and TNFβ median concentrations were significantly higher in cases when compared to controls (P < 0.01). When plasma TNFα levels were grouped under polymorphic subtypes, patients with mutant TNF- α -308A allele showed significantly higher values (P < 0.001). In addition, plasma TNFα values were significantly elevated in mutant TNF-β +252G allele (P < 0.01).
Conclusion: This study demonstrated that there is no significant association between SNPs and breast cancer susceptibility in South Indian population. However, plasma TNFα level is significantly elevated with mutant-recessive TNF-α -308 A and TNF-β +252 G alleles of patients.
Keywords: Breast cancer; inflammation; polymorphism; tumor necrosis factor.