Investigating the Relationship between rs6983267 Single Nucleotide Polymorphism Variants Located in CCAT2 Gene and Susceptibility to Thyroid Cancer in the Azeri Population of Iran
Investigating the Relationship between rs6983267 Single Nucleotide Polymorphism Variants Located in CCAT2 Gene and Susceptibility to Thyroid Cancer in the Azeri Population of Iran
Masoud Jabraili,1Solmaz Moniri Javadhesari,2,*Nasser Pouladi,3Mohammad Ali Hosseinpour Feizi,4
1. Department of Cellular and Molecular Biology, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran 2. Department of Cellular and Molecular Biology, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran 3. Department of Molecular Biology and Cancer Research, Azarbaijan Shahid Madani University, Tabriz, Iran 4. Department of Biology-Genetics, Science Faculty, Tabriz University, Tabriz, Iran
Introduction: Genetic is always one of the most effective factors in the occurrence of cancers, and thyroid cancer is no exception. Single nucleotide polymorphisms or SNPs are one of the most common forms of genetic variation in the population that are present in at least 1% of the population. Presence of SNPs within the gene sequence may affect the final products of the corresponding genes. Especially, SNPs in the genes that are participated in fundamental cellular processes can affect the cellular outcome remarkably. Long non-coding RNA molecules (lncRNAs) play a great role in a variety of important cellular processes, and their role in various disease conditions has been demonstrated frequently. These molecules are RNAs with a length of more than 200 nucleotides that are not translated into protein products. CCAT2 (Colon Cancer Associated Transcript 2), a lncRNA molecule related to Colon Cancer, has recently been found to be overexpressed in thyroid cancer. The rs6983267 SNP in CCAT2 gene with two allelic variants (G (ancestral) and T) has been introduced to be associated by some structural and functional properties of the CCAT2 transcript and susceptibility of several diseases. The aim of this study was investigating the allelic (G and T) and genotypic (GG, GT and TT) distribution of rs6983267 SNP of CCAT2 gene in the Azeri population of Iran as well as their relationship with the incidence of thyroid cancer.
Methods: Genomic DNAs were extracted from peripheral blood of 102 individuals affected by thyroid cancer (including 72 females, 26 males and 4 people with unknown gender) and 103 healthy individuals (including 73 females and 30 males), as controls, by salting-out method. The genotype of each DNA sample was determined using TETRA ARMS PCR followed by agarose gel electrophoresis. One sample of each genotype (GG, GT and TT) was sequenced through Sanger's method to ensure the accuracy of the results. The significance of the data was evaluated using the chi-square test (X2), and the odds ratio (OR) was calculated for the genotypes (using binary logistic regression models) in three genetic models; dominant, recessive and codominant.
Results: Among 102 thyroid cancer patients in this study, 31 individuals (30.4%) represented the GG genotype, 42 individuals (41.2%) GT genotype and 29 people (28.4%) TT genotype. The age range of patients was between 14 and 77 years, with an average of 39.19 years. On the other hand, in the control group, 25 people (24.3%) showed GG genotype, 45 people (43.7%) represented GT pattern, and 33 people (32%) had TT genotype. Then, the frequency of G allele in patients was estimated 51% and the frequency of T allele was estimated to be 49%. The allelic frequencies of control group were 46.1% for G allele and 53.9% for T allele. Based on the chi-square test results, no significant relationship was found between GG, GT and TT genotypes with susceptibility to thyroid cancer occurence (X2=1.000, P-value=0.607). As well, the chi-square test did not show a significant relationship between G and T alleles with thyroid cancer susceptibility (X2=0.971, P-value=0.324). The results of examining the odds ratios in three models of dominant (GG+GT vs. TT: OR=1.187, 95%CI=0.653-2.156, P-value=0.574), recessive (GG vs. GT+TT: OR=1.362, 95%CI=0.735-2.525, P-value=0.326) and codominant (GT vs. GG+TT: OR=0.902, 95%CI=0.518-1.570, P-value=0.716), and for alleles (G vs. T: OR=1.215, 95%CI=0.825-1.791, P-value=0.325) did not stablished any significant relationship.
Conclusion: In this study, the frequency of genotypes (GG, GT and TT) and alleles (G and T) in the rs6983267 single nucleotide polymorphism locus in patients was obtained to be different from control individuals. However, statistical analysis showed no significant association between genotypes and/or alleles with the occurrence of thyroid cancer in the Iranian-Azeri population (P-value>0.05). It is assumed that investigating more subjects from each patients and controls group may lead to further determine the genotypic and allelic frequencies of this SNP locus in Iranian-Azeri population.