The molecular mechanisms involved in genetic instability, which is a driving force of cancer cells from earlier stages of pathologenesis, are not fully understood. Current evidence shows that overexpression of Pol θ, a “DNA repair” polymerase specialized in the replication of damaged DNA, which is altered in breast tumors, is not a passive agent in tumor development and is able to predict patient outcome. Aberrant POLQ expression may be related to genetic instability, and also resistance to “replicative stress”, leading to changes in replicating parameters and consequent tumor development. The objective of this project is to analyze genetic variants related to POLQ as new population biomarkers of risk, progression and prognosis in hereditary (HBC) and sporadic (SBC) breast cancer in Brazil.
Materials and methods
Single Nucleotide Polymorphisms (SNPs) were systematically identified through the NCBI database. SNPs identified result in amino acid exchange in the protein and are located within exons or promoter regions. Most SNPs have not been tested in population-based studies. We recruited 211 breast cancer patients (94 SBC and 114 HBC) and 206 women without cancer. In this case-control study, we first genotyped seven SNPs (rs61757736, rs55748151, rs41545723, rs1381057, rs587553, rs13065220, rs3806614) using Taqman Real Time PCR. Data were analyzed using SPSS 18.0.
Interestingly, the rs581553SNP located in a promoter region was associated with HBC (g.121265913T>C; HBC TT=16, Control TT=8; OR=2.01, CI95%= 1.32-3.32; p<0.001). Although the Chi-Square analysis did not show any statistical difference between groups for the other SNPs, the HBC group showed more polymorphic genotypes than SBC and Control groups regarding the rs1381057 SNP (c.7538T>C; SBC TT=7, HBC TT=13, Control TT=8).
These results suggest that POLQ germline variation may be related to cancer progression in this patient group. Additional SNPs are being analyzed and the correlation between genotype and relevant clinical variables for breast cancer prognosis will be evaluated.
CNPq, FIPE-HCPA, INAGEMP.