3′UTR-HLA-G polymorphisms and circulating sHLA-G are associated with breast cancer: Evidence from a meta-analysis

Background: Human leukocyte antigen-G (HLA-G) gene polymorphisms and circulating sHLA-G have often been linked to the risk of breast cancer (BC). However, the results remain controversial. To resolve this issue, we performed a meta-analysis of HLA-G gene polymorphisms and sHLA-G levels in BC. Methods: We performed a meta-analysis on the association of HLA-G 14-bp Insertion/Deletion (Ins/Del) and HLAG +3142 C/G polymorphisms with BC as well as the relationship between sHLA-G and the disease outcome. Results: Pooled analysis showed a statistically significant association between the HLA-G 14-bp Ins/Del polymorphism and BC susceptibility for the overall population and for Caucasians. The Del allele and genotypes with at least one copy of the Del allele presented significant risks for BC. For HLA-G +3142 C/G polymorphism, the G allele significantly decreased the risk of BC for the overall population and for Caucasians, indicating that the G allele was a protective factor against BC and that the C allele was a significant risk factor for BC. The metaanalysis revealed a significantly increased level of sHLA-G patients with BC compared to the control group for the overall population, Caucasians and Asians. Conclusion: The present meta-analysis showed a major association of both HLA-G 14-bp Ins/Del and +3142 C/G polymorphisms with BC susceptibility, suggesting Del and C variants as highly significant risk factors for BC. The present study also showed significantly higher sHLA-G levels in patients with BC compared to healthy controls. Our pooled results suggested a critical role of HLA-G in BC, thereby providing evidence to use HLA-G as a biomarker and a therapeutic tool.