Qom University of Medical Sciences Journal

Thyroid cancer is one of the most common cancers in the world. Its prevalence has increased rapidly over the past 30 decades in the United States and other developing countries [1]. Adipose tissue is a complex endocrine organ that secretes compounds called adipocytokine. Adipose tissue-derived adipokines are mediators between adipose tissue and metabolic organs. Thyroid diseases affect the production of adipokines and adipocytokines [5]. Vaspin is a novel adipocytokine. Various studies have shown that vaspin is associated with increased risk of several cancer types [6]. Different results have been reported from examining the relationship between vaspin and thyroid diseases. A study showed changes in the mRNA level of  vaspin in rates with thyroid diseases and reported that thyroid diseases affect the expression of vaspin. Other study reported that thyroid hormones do not affect the expression of vaspin in humans [11, 12]. The vaspin gene composed of 6 exons and 5 introns and is located on chromosome 14 (14q32.13) [14]. Genome-wide association studies have been conducted and identified several single nucleotide polymorphisms (SNPs) in the vaspin locus which associated with serum level of vaspin. Genetic alterations seem to be the cause of changes in serum level of vaspin. The rs2236242 SNP is located in intron 4 of a vaspin gene [15]. This study aims to determine the association of vaspin rs2236242 gene polymorphism with vaspin level in women with papillary thyroid cancer (PTC) and Multinodular goiter (MNG).
Methods
This case-control study was conducted on 134 women referred to Shariati Hospital, Tehran, Iran. They all were Iranian. They were divided into three groups; PTC (n=49), MNG (n=30) and control (n=55). Blood samples (10 ml) were taken from participants after an overnight fast for 12-14 hours; 5 ml blood sample was poured into a tube containing EDTA (Ethylene diamine tetra acetic acid) for DNA extraction and the remaining 5 ml sample was poured into a tube without EDTA for serum preparation. Serum was prepared by centrifugation and divided into 1 ml Eppendorf microtubes for avoiding freeze-thaw cycles and kept at −80 °C until testing. Genomic DNA was extracted from peripheral blood samples using the standard salting out method.  The serum vaspin level measurement was performed by Sandwich ELISA kit (ZellBio, Germany) [9، 15]. The genotype determination of vaspin rs2236242 polymorphism was performed using the tetra primer-amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method. The validity of PCR and the DNA fragments for rs2236242 were assessed using a 8% polyacrylamide gel electrophoresis [15]. The result of electrophoresis was observed by the transilluminator. Statistical analysis was carried out in SPSS v.20 software (SPSS, Chicago, IL, USA). Continuous variables were described as mean ± standard deviation, and categorical variables were expressed as number (%). Normality of distribution for quantitative variables was examined by the Kolmogorov-Smirnov test. In cases the distribution was not normal, the Mann-Whitney U test and Kruskal–Wallis  test were used for comparison of the study groups; otherwise, Independent T-test and ANOVA were used. The significance level was set at 0.05.
Results
There was no significant difference in serum vaspin level among the three groups. There was no significant association between genotypes of rs2236242 gene polymorphism and serum vaspin level in any groups. Logistic regression analysis showed a significant difference in frequency of TA genotype of rs2236242 polymorphism between PTC and MNG groups compared to the control group (P< 0.05). There was a significant difference in frequency of TA genotype between MNG and control groups. The TT genotype increased the risk of MNG. The frequency of TA genotype was higher in the control group (P< 0.05). Therefore, TA genotype showed protective effects against PTC and MNG.
Discussion
There is no significant difference in vaspin level between PTC, MNG and control groups. There is no association between rs2236242 gene polymorphism and serum vaspin level. The TA genotype of rs2236242 has a protective effect against MNG and PTC. Since adipokines have important role in diagnosing and progressing cancers, the study of the relationship between adipokines, including vaspin, in different populations and using larger sample size, is needed to understand their mechanism of action and develop treatment strategies
Ethical Considerations
Compliance with ethical guidelines
In this study, all procedures were in accordance with the guidelines of the declaration of Helsinki. The study was approved by the research ethics committee of Islamic Azad University, Tehran Medical Branch (code: IR.IAU.TMU.REC.1396.309).
Funding
This study was not funded by any funding agency.
Authors contributions
All authors contributed equally to preparing this article
Conflicts of interest
The authors declare no conflict of interest.
Acknowledgements
The authors would like to thank Dr. Maryam Zarkesh and Ms. Laleh Haghighi from Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences for technical assistance.