Association between the MDM2 T309G polymorphism and leukemia risk: a meta-analysis

Evaluation of TP53 Codon 72, P21 Codon 31, and MDM2 SNP309 Polymorphisms in Iranian Patients with Acute Lymphocytic Leukemia

BACKGROUND

The tumor suppressing protein p53 and its downstream effector p21 play important roles in cell cycle regulation. Deficiency or deactivation of these proteins as a result of gene alterations has been indicated in several cancers. Such genetic variations could be considered as susceptibility indicators in acute lymphocytic leukemia (ALL). Therefore, we investigated the associations between ALL risk and TP53 codon 72, p21 codon 31, and MDM2 SNP309 polymorphisms in an Iranian population.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the MDM2 T309G (rs2279744), TP53 codon Arg72Pro (rs1042522), and p21 Ser31Arg (rs1801270) single nucleotide polymorphisms (SNPs). This study was performed in 115 ALL patients and 115 healthy controls in Khuzestan province in southwest Iran.

RESULTS

In the control group and ALL patients, p21 Ser/Arg, and MDM2 TG and GG genotypes were associated with significant 1.81-fold (95% confidence interval CI= 1.008-3.267; P < 0.05), 11.07-fold (95% CI= 5.10-24.05; P < 0.0001), and 19.41-fold (95% CI= 8.56-43.99; P < 0.0001) increased risks for ALL, respectively. The TP53 72 Arg allele was significantly more prevalent in ALL patients (56.96%) than in control subjects (47.39%), and was significantly associated with ALL (OR= 1.47; 95% CI = 1.017-2.121, P < 0.05).

CONCLUSION

The MDM2T309G and the p21 Ser31Arg SNPs indicate a significantly increased risk for developing ALL in Khuzestan province.

Role of the MDM2 promoter polymorphism (-309T>G) in acute myeloid leukemia development

BACKGROUND

The human homologue of the mouse double minute 2 (MDM2) gene is a negative regulator of Tp53. MDM2-309T>G a functional promoter polymorphism was found to be associated with overexpression thereby attenuation of Tp53 stress response and increased cancer susceptibility. We have planned to evaluate the possible role of MDM2-309T>G polymorphism with risk and response to chemotherapy in AML.

MATERIALS AND METHODS

A total of 223 de novo AML cases and 304 age and sex matched healthy controls were genotyped for the MDM2-309T>G polymorphism through the tetra-primer amplification refractory mutation system (ARMS)-PCR method. In order to assess the functional relationship of -309T>G SNP with MDM2 expression level, we quantified MDM2 mRNA in 30 primary AML blood samples through quantitative RT-PCR. Both the (-309T>G) genotypes and the MDM2 expression were correlated with disease free survival (DFS) rates among patients who have achieved complete remission (CR) after first induction chemotherapy.

RESULTS

MDM2-309T>G polymorphism was significantly associated with AML development (p<0.0001). The presence of either GG genotype or G allele at MDM2-309 confered 1.79 (95% CI: 1.12-2.86; p<0.001) and 1.46 fold (95%CI: 1.14-1.86; p=0.003) increased AML risk. Survival analysis revealed that CR+ve cases with GG genotype had significantly increased DFS rates (16months, p=0.05) compared to CR+ve TT (11 months) and TG (9 months) genotype groups. Further, MDM2 expression was also found to be significantly elevated in GG genotype patients (p=0.0039) and among CR+ve cases (p=0.0036).

CONCLUSIONS

The MDM2-309T>G polymorphism might be involved in AML development and also serve as a good prognostic indicator.