An update meta-analysis and systematic review of TAP polymorphisms as potential biomarkers for judging cancer risk

Objective: Transporter associated with antigen processing protein (TAP) is a heterodimer protein consist of TAP1 and TAP2, act a pivotal part in the immune surveillance. In recent days, controversial relationships were reported between TAP polymorphisms and cancer risk, thus, a systematic meta-analysis was performed to resolve this discrepancy.

Methods: We searched the PubMed, EMbase, Web of Science, CNKI and Wanfang databases, the cited references were also manually searched again, covering all the papers published until March 25, 2018. Quality assessment was conducted using the Newcastle-Ottawa Scale. All the meta-analysis was conducted with Stata version 12.0 software to assess the strength of the association.

Results: 4719 cases and 4215 controls from 24 case-control studies related to TAP polymorphisms were enrolled. There was no significant association between TAP1-rs1135216, TAP1-rs4148873, TAP2-rs2228396, TAP2-rs241447 and TAP2-rs4148873 and cancer sensibility. Interestingly, a significant positive association was observed between TAP2 rs4148876 C/T polymorphism and increase cancer risk in homozygote and recessive models. Further in-silico results indicated the expression of TAP2 in cancer tissue is higher than that in normal tissue (cervical cancer, TPM = 70.2 vs. 24.0 respectively, P < 0.01; acute myeloid leukemia, TPM = 52.5 vs. 8.8 respectively, P < 0.01), and influence the survival time of acute myeloid leukemia patients (Log-rank P < 0.05).

Conclusions: Our finding suggested that TAP1-rs1135216, TAP1-rs4148873, TAP2-rs2228396, TAP2-rs241447 and TAP2-rs4148873 might not be involved in cancer risk, but the T allele of TAP2-rs4148876 might be a potential biomarker for judging cancer risk, and larger-scale studies are required to confirm our findings.