ABSTRACT
BACKGROUND:The mouse double minute 2 (MDM2) is a negative regulator of the p53 tumor suppressor protein.Overexpression of MDM2 is associated with poor survival and is a useful predictive factor for poor prognosisin various cancers in human. Studies revealed a genetic polymorphism located in intron 1 of the MDM2gene, MDM2-SNP309, (a change from T to G) is main functional polymorphism and important to developtumors. However, inconsistent associations between the MDM2-SNP309 and the risk or early onset ageof human different cancers have been reported worldwide. These conflicting results may have dependedon different patient subgroups and ethnicities studies. We studied the association of the MDM2-SNP309polymorphism andbladder cancer in Mongolian patients for the first time.OBJECTIVE:To investigate association between MDM2-SNP309 and the risk bladder cancer or early onset age of thecancer in Mongolian patients.MATERIALS AND METHODS:We genotyped MDM2-SNP309 in 44 patients with bladder cancer and 44 age and gender matched healthycontrols among Mongolian people.Genomic DNA was extracted from whole blood samples by the standardmethod of Qiagen mini blood DNA extraction kit (Qiagen Inc., Valencia, CA) and PCR amplification wasperformed using 100 ng genomic DNA template according to manufacturer’s protocol (Invitrogen, Carlsbad,CA). MDM2 SNP309 genotyping was carried out by restriction fragment length polymorphism assay.RESULTS: The allele frequencies of MDM2 SNP309 in the 44 bladder cancer patients were wild-type (T/T) 27.3%,homozygous (G/G) 34.1% and heterozygous (T/G) 38.6% whereas in the control cases were wild-type(T/T) 29.5%, homozygous (G/G) 20.5% and heterozygous (T/G) 50.0%. The proportion of homozygous(G/G) genotype was higher for bladder cancer cases than for healthy controls. Compared to the low-risk(wild type) genotype, an increased risk association with bladder cancer was shown for the GG genotype(OR=2.0, 95% CI=1.03-1.84). There is also a significant difference in median age onset of bladder cancerbetween GG low and high risk genotypes T/T and T/G (p=0,003)( p=0.0001), respectively (Figure2).CONCLUTION: The current sample data suggests that MDM2 SNP309 GG genotype may be associated withthe risk of bladder cancer as well as an earlier age onset in Mongolian patients with bladder cancer.