Association Of Cyclin D1 Gene A870G Polymorphism With The Development Of Salivary Gland Tumors

Background:Expression of Cyclin Dl is believed to lead to progression through the G1 to S cell cycle checkpoint, and both experimental and pathological evidence suggest that overexpression of this protein may increase the risk of several cancers. Cyclin D1 A870G polymorphism, in the splice donor region of exon 4, may modulate expression of Cyclin D1 protein and is associated with the development of several types of tumor. Salivary gland tumors (SGT) constitute an important area in the field of oral and maxillofacial pathology. In this study, we aim to analyze the association between Cyclin D1 A870G polymorphism and development of SGT.Objective:We aimed to analyze the association between Cyclin Dl A870G polymorphism and development in salivary gland tumors.Methods:The study population included a total of 102 individuals (cases) who were diagnosed at The First Affiliated Hospital of Dalian Medical University between October 2008 and February 2010. One hundred and one non-cancer patients from the same hospitals and dental clinics were used as the controls. Genomic DNA was isolated from the cell pellet using Oral Mucosa Cell DNA Purification Kit. The genomic fragment containing Cyclin D1 A870G was amplified by a two-step nested PCR with four primers:P1,5'-ACAGCCTCCTTCCCTCTCTC-3'(outerforward);P2,5'-CTGG GACATCACCCTCACTT-3'(outer reverse);P3,5'-GTGAAGTTCATTTCCA ATCCGC-3'(inner forward);and P4,5'-GGGACATCACCCTC ACTTAC-3'(inn-er reverse). The first-and second-round PCR amplifications were carried out using Taq DNA polymerase (Takara, Japan). PCR products were digested with 1.25U ScrFl at 37℃overnight, and visualized by electro-phoresis on 3% agarose gels to identify the G870A polymorphic alleles. Samples with the AA genotype produced 1 band (167 bps), samples with the GA genotype produced 3 bands (167 bps,145 bps, and 22 bps), and samples with the GG genotype produced 2 bands (145 bps and 22 bps). For confirming Cyclin D1 A870G polymorphism, randomly selected cases comprising of all types of genotypes were sequenced. Data analysis was performed using software SPSS 13.0 for Windows.Hardy-Weinberg equilibrium analysis was performed to compare observed and expected genotype frequencies using a chi-square test.Results:Significant difference was observed in the distribution in Cyclin D1 A870G polymorphism between cases and controls. (p=0.004). The AG (p=0.002; OR,3.466; 95% CI,1.595-7.532) and AA (p=0.003; OR,3.133; 95% CI,1.464-6.705) genotypes of Cyclin D1 significantly increased in patients with STG, compared with controls. A allele increased in SGT (OR=2.169,95% CI 1.415-3.326,p=0.001), compared with G allele. Cyclin Dl A allele increased the risk for both benign (p< 0.001; OR,2.352; 95% CI,1.463-3.782) and malignant (p=0.029; OR,3.555; 95% CI, 1.137-11.108) SGT. Cyclin D1 A allele increased the risk for salivary gland pleomorphic adenoma (p=0.002; OR,2.229; 95% CI,1.350-3.681).Conclusion:There was a significant association between Cyclin gene A870G polymorphism and the development of SGT. The AG and AA genotypes of Cyclin Dl increased the risk for benign and malignant SGT. Cyclin D1 A allele increased risk in benign and malignant SGB as well. The AG and AA genotypes of Cyclin D1 gene increased the risk for pleomorphic adenoma. Cyclin D1 A allele increased the risk for pleomorphic adenoma.