The PIK3R1 and PHLPP2 genes encode the p85 alpha subunit of PI3K and a phosphatase for AKT, respectively, which play a direct role in regulating the PI3K-AKT pathway that promotes cell survival, growth, and differentiation. While most attention is focused on the factors that positively affect this pathway, negative regulation is equally important. The aim of this study was to investigate the association of SNPs rs61733127 (L1016S) in PHLPP2 gene and rs3730089 (Met326Ile) in PIK3R1 gene with colon and breast cancer, respectively because both SNPs have been reported to play a functional role in corresponding encoded enzymes and both genes are negatively involved in regulating the PI3K-AKT pathway. 139 colon and 149 breast cancers patients and 279 healthy controls were included in the present study. The target SNPs were genotyped using tetra- ARMS-PCR. In addition, the genotypes of 10 samples for each SNP were confirmed by sequencing. Statistical analysis was performed using SPSS 21.0 and by Fisher exact, T, χ2 and logistic regression tests. As revealed, the genotype AG (OR = 2.18, p = 0.001, CI = 1.36-3.50) and allele G (OR = 1.92, p = 0.001, CI = 1.30-2.84) of rs61733127 in the PHLPP2 gene significantly increased the risk of colon cancer. In addition, genotype AA (OR = 0.2, p = 0.001, CI = 3.00-8.00) and allele A (OR = 0.5, p = 0.001, CI = 1.00-4.00) of rs3730089 in the PIK3R1 gene significantly decreased the risk of breast cancer. The results suggest that SNPs in genes involved in regulating of PI3K-AKT pathway can be used as a marker for susceptibility to colon and breast cancers.
Keywords: PHLPP2 gene; PI3K-AKT pathway; PIK3R1 gene; breast cancer; colon cancer; rs3730089; rs61733127.