The current study examined the effects of BAX and BCL2 polymorphisms and methylation as well as mRNA expression on susceptibility to PE. After delivery, the placentas were collected from 92 women with PE, as well as 106 normotensive pregnant women. The BAX rs4645878 and BCL2 rs2279115 polymorphisms were genotyped by the PCR-RFLP method. Methylation-specific PCR (MSP) was used for analysis of promoter methylation. mRNA expression was assayed by Quantitative RT-PCR. In addition, in silico analysis was performed by bioinformatics tools. There was no relationship between PE and placental BAX rs4645878 and BCL2 rs2279115 polymorphisms. The groups were not significantly different regarding the promoter methylation of BAX gene. Nonetheless, the MM status of BCL2 promoter had a significantly higher frequency in the PE group and was associated with 2.7-fold higher risk of PE (OR = 2.7, 95% CI = 1.3-5.6; P = 0.01). The relative mRNA expression of BCL2 was decreased in the placentas of PE women (P < 0.0001). The expression of BAX gene was not significantly different between the two groups. There was no association between placental BAX rs4645878 and BCL2 rs2279115 polymorphisms and mRNA expression levels. In silico analysis indicated that BAX rs4645878 and BCL2 rs2279115 polymorphisms were located in the core recognition site of different transcription factors and these substitutions of wild allele resulted in the loss and/ or change of these binding sites and subsequently may alter BCL2 and BAX expression. This study showed that the BAX and BCL2 polymorphisms and BAX promoter methylation were not associated with PE risk. The BCL2 promoter methylation was associated with lower BCL2 expression and higher PE susceptibility.
Keywords: Apoptosis; Expression; Methylation; Polymorphism; Preeclampsia.