The incidence rate of papillary thyroid cancer (PTC) has increased over the past decades, but the pathogenesis remains unclear. rs2910164, located in pre-miR-146a, has been studied in PTCs with different ethnicity, but the results were inconsistent. Here we evaluate the association between rs2910164 polymorphism and PTC and investigate the effect of this polymorphism on patients’ clinicopathological characteristics. 1238 PTC patients and 1275 controls, all Han population, from Northern China, were included in our study. rs2910164 was genotyped using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS). Analysis of inheritance model was performed using the SNPStats program. Strength of association was assessed by odds ratio (OR) and 95% confidence interval (CI). Overall, no statistical difference in rs2910164 genotype distribution and allelic frequencies between cases and controls was found, and patients with different genotypes had similar clinicopathological characteristics in terms of stage, location, concurrent of benign thyroid tumor, and thyroiditis, while, as the number of G alleles increased, proportion of patients aged ≥45 years and those without metastasis increased (
Thyroid cancer is the most common endocrine malignancy with an incidence rate that has doubled over the past ten years and ranked fifth in 2014 (6%) from a previous eighth position (3%) as a cause of all new cancer cases in females [
MicroRNAs (miRs) are noncoding RNAs that are transcribed from endogenous DNA molecules. The first miR was identified in 1993 and more than one thousand miRs have been discovered in human genome by now [
Pre-miR-146a C/G polymorphism, designated rs2910164, is encoded on chromosome 5q33 and located in the precursor stem region, +60 relative to the first nucleotide of pre-miR-146a, opposite to the mature miR-146a sequence [
With a case-control study design, 1238 PTC patients and 1275 healthy controls were involved in our study. All PTC patients were pathologically diagnosed and received surgical treatment at the China-Japan Union Hospital of Jilin University in Changchun, Jilin province, China, from January 2010 to December 2014. The histological type of the PTCs was classical PTC, not the follicular variant PTC (fvPTC). The controls consisted of two groups: 360 participants recruited from the First Bethune Hospital of Jilin University in Changchun, Jilin province, China, for a routine health examination, as previously published [
For DNA extraction, about 5 mL peripheral venous blood was collected from each subject and stored at −20°C in nonanticoagulant, plexiglass tubes with the ClotBlood DNA kit (Cwbio, Beijing, China) used for genomic DNA extraction and ultraviolet spectrophotometer (Beckman, USA) used for measuring the concentration and purity of the extracted DNA.
For SNP genotyping, we used the Assay Designer 3.1 to design the primers of polymerase chain reaction (PCR): 5′-ACGTTGGATGCCACGATGACAGAGATATCC-3′ (forward) and 5′-ACGTTGGATGGAACTGAATTCCATGGGTTG-3′ (reverse). PCR was performed as previously published [
Continuous variables were presented with mean and standard deviation and tested using independent samples
Our study included 1238 PTC cases and 1275 healthy controls. The mean ages of cases and controls were 43.43 and 43.38 years, respectively, and the female-to-male rate ratio was more than 2.5 in both groups. Distributions of age and gender were similar between the two groups (
Characteristics of the study subjects.
Variables | Cases ( |
Controls ( |
|
|
---|---|---|---|---|
Age | 43.43 ± 9.204 | 43.38 ± 9.311 | −0.123 | 0.902 |
Gender | ||||
Male | 321 (25.9) | 339 (26.6) | 0.132 | 0.716 |
Female | 916 (74.1) | 936 (73.4) | ||
History of thyroid disease | ||||
Yes | 114 (9.4) | |||
No | 1093 (90.6) | |||
Family history | ||||
Yes | 160 (13.6) | |||
No | 1017 (86.4) | |||
Smoking | ||||
Nonsmokers | 1066 (88.8) | |||
Smokers | 119 (9.9) | |||
Ex-smokers | 15 (1.2) | |||
Stage | ||||
0-I | 597 (81.7) | |||
II | 36 (4.9) | |||
III | 35 (4.8) | |||
IV | 63 (8.6) | |||
Metastasis (pN+) | ||||
Yes | 399 (33.6) | |||
No | 788 (66.4) | |||
Location | ||||
Unilateral | 787 (70.5) | |||
Bilateral | 311 (27.9) | |||
Isthmus | 18 (1.6) | |||
Diameter | ||||
≤1 cm | 598 (50.9) | |||
>1 cm | 578 (49.1) | |||
Benign tumor | ||||
Yes | 625 (51.5) | |||
No | 588 (48.5) | |||
PTC/benign | ||||
Same side | 176 (29.3) | |||
Opposite sides | 425 (70.7) | |||
Thyroiditis | ||||
Yes | 106 (8.7) | |||
No | 1107 (91.3) |
HWE test indicated that the genotype distribution in control group was consistent with that expected under the HWE (
Genotype and allele frequencies of the cases and controls.
rs2910164 | Cases | Controls |
|
|
---|---|---|---|---|
Genotype | ||||
CC | 386 (32.0) | 392 (31.5) | 0.079 | 0.961 |
CG | 601 (49.8) | 619 (49.8) | ||
GG | 221 (18.3) | 232 (18.7) | ||
Allele | ||||
C | 1373 (56.8) | 1403 (56.4) | 0.077 | 0.781 |
G | 1043 (43.2) | 1083 (43.6) |
Association between rs2910164 genotypes and PTC under different models of inheritance (adjusted by age and gender).
Model | Genotype | Cases | Controls | OR (95% CI) |
|
---|---|---|---|---|---|
Codominant | CC | 383 (31.8) | 392 (31.5) | 1.00 | |
CG | 600 (49.8) | 619 (49.8) | 0.97 (0.80–1.18) | 0.85 | |
GG | 221 (18.4) | 232 (18.7) | 0.94 (0.74–1.21) | 0.71 | |
|
|||||
Dominant | CC | 383 (31.8) | 392 (31.5) | 1.00 | |
CG/GG | 821 (68.2) | 851 (68.5) | 0.96 (0.80–1.16) | 0.69 | |
|
|||||
Recessive | CC/CG | 983 (81.6) | 1011 (81.3) | 1.00 | |
GG | 221 (18.4) | 232 (18.7) | 0.96 (0.77–1.20) | 0.72 | |
|
|||||
Overdominant | CC/GG | 604 (50.2) | 624 (50.2) | 1.00 | |
CG | 600 (49.8) | 619 (49.8) | 0.99 (0.84–1.18) | 0.93 | |
|
|||||
Log-additive | — | — | — | 0.97 (0.86–1.10) | 0.64 |
Table
The clinical characteristics of the PTC cases by rs2910164 genotypes.
Variables | CC | CG | GG |
|
|
|
---|---|---|---|---|---|---|
Gender | ||||||
Male | 99 (25.6) | 152 (25.3) | 60 (27.1) | 0.283 | 0.868 | 0.74 |
Female | 287 (74.4) | 448 (74.7) | 161 (72.9) | |||
Age | ||||||
<45 | 268 (70.0) | 323 (53.7) | 72 (32.6) | 79.974 |
|
|
≥45 | 115 (30.0) | 278 (46.3) | 149 (67.4) | |||
History of thyroid disease | ||||||
Yes | 34 (9.0) | 61 (10.5) | 14 (6.5) | 3.109 | 0.211 | 0.471 |
No | 345 (91.0) | 521 (89.5) | 203 (93.5) | |||
Family history | ||||||
Yes | 49 (13.2) | 86 (15.2) | 23 (10.9) | 2.512 | 0.285 | 0.634 |
No | 323 (86.8) | 481 (84.8) | 188 (89.1) | |||
Smoking | ||||||
Nonsmokers | 337 (90.6) | 515 (88.3) | 189 (87.9) | 7.009 |
0.182 | 0.1 |
Smokers | 33 (8.9) | 62 (10.6) | 20 (9.3) | |||
Ex-smokers | 2 (0.5) | 6 (1.0) | 6 (2.8) | |||
Stage | ||||||
0-I | 189 (82.9) | 287 (82.7) | 107 (78.1) | 5.971 | 0.426 | 0.521 |
II | 8 (3.5) | 17 (4.9) | 11 (8.0) | |||
III | 14 (6.1) | 13 (3.7) | 6 (4.4) | |||
IV | 17 (7.5) | 30 (8.6) | 13 (9.5) | |||
Metastasis (pN+) | ||||||
Yes | 145 (39.0) | 179 (31.3) | 59 (27.7) | 9.453 |
|
|
No | 227 (61.0) | 393 (68.7) | 154 (72.3) | |||
Location | ||||||
Unilateral | 244 (70.1) | 377 (69.8) | 149 (74.9) | 4.958 | 0.292 | 0.217 |
Bilateral | 95 (27.3) | 157 (29.1) | 47 (23.6) | |||
Isthmus | 9 (2.6) | 6 (1.1) | 3 (1.5) | |||
Diameter | ||||||
≤1 cm | 168 (46.2) | 307 (54.1) | 113 (52.6) | 5.831 | 0.054 | 0.07 |
>1 cm | 196 (53.8) | 260 (45.9) | 102 (47.4) | |||
Benign tumor | ||||||
Yes | 183 (48.3) | 309 (52.8) | 119 (54.3) | 2.673 | 0.263 | 0.12 |
No | 196 (51.7) | 276 (47.2) | 100 (45.7) | |||
PTC/benign | ||||||
Same side | 50 (28.4) | 81 (27.3) | 36 (31.6) | 0.751 | 0.687 | 0.632 |
Opposite sides | 126 (71.6) | 216 (72.7) | 78 (68.4) | |||
Thyroiditis | ||||||
Yes | 30 (7.9) | 61 (10.4) | 15 (6.8) | 3.247 | 0.197 | 0.923 |
No | 349 (92.1) | 524 (89.6) | 204 (93.2) |
Association of rs2910164 and clinical characteristics under different models of inheritance with OR (95% CI) (adjusted by age and gender).
Characteristics | Codominant 1 | Codominant 2 | Dominant | Recessive | Overdominant | Log-additive |
---|---|---|---|---|---|---|
Stage (III-IV versus 0–II) | 0.65 (0.39–1.09) | 0.75 (0.37–1.55) | 0.67 (0.41–1.10) | 1.02 (0.55–1.91) | 0.73 (0.46–1.13) | 0.82 (0.57–1.18) |
Metastasis (yes versus no) | 0.84 (0.63–1.12) | 0.86 (0.58–1.28) | 0.85 (0.64–1.11) | 0.97 (0.68–1.37) | 0.88 (0.69–1.14) | 0.91 (0.75–1.11) |
Location (bilateral versus unilateral) | 1.20 (0.88–1.63) | 0.99 (0.64–1.51) | 1.15 (0.85–1.55) | 0.87 (0.60–1.26) | 1.20 (0.92–1.57) | 1.02 (0.83–1.26) |
Diameter (>1 cm versus ≤1 cm) |
|
0.79 (0.55–1.13) |
|
0.97 (0.71–1.32) | 0.80 (0.63–1.01) | 0.86 (0.72–1.03) |
Benign tumor (yes versus no) | 1.12 (0.86–1.46) | 1.10 (0.77–1.56) | 1.12 (0.87–1.44) | 1.02 (0.75–1.38) | 1.08 (0.86–1.36) | 1.06 (0.89–1.26) |
Thyroiditis (yes versus no) | 1.47 (0.92–2.36) | 1.04 (0.53–2.03) | 1.37 (0.87–2.18) | 0.80 (0.44–1.43) | 1.45 (0.97–2.19) | 1.08 (0.80–1.47) |
Codominant 1: CG versus CC; codominant 2: GG versus CC; dominant: CG/GG versus CC; recessive: GG versus CC/CG; overdominant: CG versus CC/GG.
Significant OR (95% CI) in bold.
Scientific research on gene polymorphisms involved in carcinogenesis and cancer progression has been a hot area of interest for several decades and the advent of the next generation sequencing technology and GWAS is accelerating the pace of development in this area. Many studies have revealed the importance of miRs in various biological processes, including their roles in several cancers (e.g., thyroid cancer), and provided us with useful information [
Pre-miR-146a was first found in mouse and several studies have shown that it plays an important role in tumorigenesis and cancer metastasis [
In some retrospective case-control studies carried out on Chinese Han ethnic subjects, rs2910164 has been found to be associated with the risk of several kinds of cancers. Zhou et al. found that the GG genotype of rs2910164 was significantly associated with an increased risk of gastric cancer, which was more notable in the pooled analysis when another follow-up replication study was added, and the association was more significant in younger individuals than the older ones [
It should be mentioned that several meta-analyses tried to explain the association between rs2910164 and cancer risk but got no significant results. Two studies reviewed genetic association studies on common microRNA polymorphisms and hepatocellular carcinoma susceptibility, but no significant association was found for rs2910164 [
Age, as a well-recognized prognostic determinant in well-differentiated thyroid cancer (WDTC), has been adopted in many thyroid cancer predictive models and prognostic scoring systems [
Our study demonstrated no association between rs2910164 polymorphism and risk of PTC, as well as its clinicopathological characteristics, in a Chinese Han population. Our results should be interpreted with caution for the ethnicity restriction and relatively small sample size. Furthermore, a considerable number of controls who self-reported no metabolic disease, thyroid disease, or malignancy were included in the study, which might be a potential for bias in the study. However, it is necessary to conduct that further studies with larger sample size are needed to validate our results, and studies with more detailed data estimating the interaction between rs2910164 and environmental factors may provide a better understanding of the role of rs2910164 in PTC development. Nevertheless, our study provides evidence for further studies on different ethnicity and larger sample size in this field.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors would like to thank Dr. Chunyan Zhao and Dr. Huiping Zhang for their critical reading of this paper. The authors would like to thank Lizhe Ai, Guang Yang, Hongqin Xu, and Chong Wang in the Department of Epidemiology and Biostatistics, School of Public Health, Jilin University, for their assistance in data collection and experiment. The authors also would like to thank Wen Wen in the Department of Thyroid and Parathyroid Surgery, China-Japan Union Hospital, Jilin University, for her assistance in data collection. The authors’ study was supported by the National Natural Science Foundation of China (no. 30870952), the Natural Science Foundation of Jilin Province in China (no. 201015176), Jilin Provincial Science & Technology Department (no. 20140413016GH), and Graduate Innovation Fund of Jilin University (no. 2014109).