Progesterone Receptor (PGR) Gene Variants Associated with Breast Cancer and Associated Features: a Case-Control Study

Insofar as altered estrogen receptor-progesterone receptor (PR) expression contribute to breast cancer pathogenesis, previous studies examined the association of genetic variation in PR gene (PGR) with breast cancer, but with mixed outcome. We evaluated the association between PGR variants, and breast cancer and associated features. A retrospective case-control study involving 183 female breast cancer patients, and 222 control women. PGR genotyping was done by real-time PCR. Minor allele frequencies of rs1042838, rs590688, and rs10895068 PGR gene polymorphisms were significantly higher in breast cancer patients compared to controls. Patients carrying rs1042838 G/T, rs590688 C/C, and rs10895068 G/A genotypes had higher risk of breast cancer, while carriage of rs3740753 G/G genotype was associated with marginal reduction in breast cancer risk. In addition, carriage of rs1042839, rs3740753, and rs10895068 minor allele was associated with Her2 status, while rs3740753 and rs10895068 were associated with effective hormone replacement therapy. Furthermore, carriage of rs10895068 minor allele in breast cancer women were also associated with age at first pregnancy, hormone receptor (RH) status, and previous use of oral contraceptives. PGR haploview analysis documented moderate-strong linkage disequilibrium (non-random association of alleles at different loci) between 7 of the 8 tested PGR SNPs, thus allowing construction of 7-locus PGR haplotypes. Two haplotypes, ATGCCGA and GTGCCGA, both containing rs590688, were positively associated with breast cancer, thus assigning a breast cancer-susceptible nature to these haplotypes. PGR rs1042838, rs590688, and rs10895068, and ATGCCGA and GTGCCGA haplotypes are related with increased breast cancer susceptibility in Tunisian women.