PD-1 polymorphisms are associated with sporadic breast cancer in Chinese Han population of Northeast China.

The programmed death-1 (PD-1) is a potent immunoregulatory molecule which is responsible for the negative regulation of T-cell activation and peripheral tolerance. In order to investigate the association between polymorphisms of PD-1 and breast cancer, a case-control study was conducted in Chinese female population consisting of 490 cases with breast cancer and 512 age-matched healthy individuals from Heilongjiang Province of China. Four polymorphisms of the PD-1 gene, including rs36084323 (PD-1.1), rs7421861, rs2227982 (PD-1.9), and rs2227981 (PD-1.5), were selected and genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The frequencies of PD-1.1 GG genotype and PD-1.5 CT genotype were significantly lower in cases compared with controls (P = 0.020 and 0.004, respectively), and PD-1.5 CC genotype and C allele had higher frequencies in cases (P = 0.003 and 0.010). In haplotype analysis, we observed that the frequencies of ATTC and GTCT haplotypes were lower in cases than those of in controls (P = 0.0055 and 0.0012, respectively), whereas the GTCC and ATCC haplotypes had higher frequencies in cases (P = 0.0040 and 0.00008037, respectively). Additionally, strong association was showed between PD-1.1 and P53, and haplotype CCTA was associated with ER status. These results primarily suggest that PD-1 gene polymorphisms may affect the breast cancer risk and prognosis in Chinese Han females of Heilongjiang Province in Northeast China.