Quantitative Assessment the Relationship between p21 rs1059234 Polymorphism and Cancer Risk

Analysis of polymorphisms, promoter methylation, and mRNA expression profile of maternal and placental P53 and P21 genes in preeclamptic and normotensive pregnant women

Background

Preeclampsia (PE), as a multisystem disorder, is associated with maternal hypertension and proteinuria. Apoptosis seems to be involved in the pathophysiology of PE, although its precise pathogenic mechanisms are not well established. In this study, we aimed to identify the association between maternal TP53-rs1042522, P21-rs1801270, and P21-rs1059234 polymorphisms and PE. In addition, we examined the effects of promoter methylation and TP53 and P21 polymorphisms on placental mRNA expression in PE women.

Methods

The blood of 226 PE women and 228 normotensive pregnant women was examined in this study. In addition, the placentas were genotyped in 109 PE and 112 control women. The methylation status was assessed by a methylation-specific PCR assay, while mRNA expression was examined via Quantitative Real Time PCR.

Results

The maternal and placental P21-rs1801270 CA genotype had a significant association with the reduced risk of PE. In the dominant, recessive, and allelic models, maternal/placental P21-rs1059234 polymorphism had no statistically significant association with the risk of PE. On the other hand, the reduced risk of PE was associated with maternal, but not placental TP53-rs1042522 polymorphism in the dominant and recessive models. The maternal and placental P21-rs1801270 polymorphism was associated with PE risk. The maternal P21 T_rs1059234C_rs1801270 haplotype was associated with 3.4-fold increase in PE risk, However the maternal P21 T_rs1059234A_{rs 1801270} haplotype and placental C_rs1059234CA _rs1801270 haplotype led to 0.5 and 0.4-fold decrease in PE risk, respectively. PE women showed 5.6 times higher levels of placental mRNA expression of TP53 gene, although it was not associated with rs1042522 polymorphism. The relative placental mRNA expression of P21 gene was 0.2 in PE women. It was also 2.4 times higher in individuals with rs1801270CA genotype than those with AA genotype. The hyper-methylation of P21 and TP53 genes in the promoter region was associated with a 3.4-fold and 3-fold increase in PE risk, respectively. However, no association was found between P21 and TP53 mRNA expression and promoter methylation.

Conclusion

In conclusion, P21-rs1801270 and TP53-rs1042522 polymorphisms were involved in reduced risk of PE. P21-rs1801270 was associated with decreased P21 mRNA expression. The hyper-methylation of P21 and TP53 genes in the promoter region was associated with a higher PE risk.

The effects of p21 gene C98A polymorphism on development of uterine leiomyoma in southeast Iranian women

Uterine leiomyoma (UL) is a monoclonal tumor which arises from uninhibited proliferation of a single myometrial cell; therefore, the imbalance in cell cycle regulation could be a key event in its development. In the present study, we aimed to assess the association of p21 gene polymorphisms and UL. Genomic DNA was extracted from blood samples of 154 women with UL and 197 age-, BMI-, and ethnically matched controls. p21 C98A (rs1801270) and C70T (rs1059234) polymorphism genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The CA genotype of p21 C98A polymorphism was significantly higher in UL women (28 %) compared to the controls (18 %), and the UL risk was 1.8-fold greater in women with CA genotype compared to CC genotype before and after adjusting for age, BMI, and ethnicity (OR, 1.8 [95 % CI, 1.1 to 3]; P = 0.02). There was no association between the AA genotype of p21 C98A polymorphism and UL. Moreover, the frequency of p21 98A allele was significantly higher in the UL women compared to controls (17 vs. 12 %, p = 0.04). The p21 C70T polymorphism did not correlate with UL before and after adjusting for age, BMI, and ethnicity. There was no difference in haplotype frequency of p21 C70T and C98A polymorphisms between UL patients and the controls. CA genotype of p21 C98A polymorphism may be a risk factor for UL susceptibility; however, p21 C70T polymorphism did not associate with UL.