Association between GWAS-Derived rs966423 Genetic Variant and Overall Mortality in Patients with Differentiated Thyroid Cancer.

PURPOSE: Five germline genetic variants (rs116909374, rs965513, rs944289, rs966423, and rs2439302) have been associated in genome-wide association studies (GWAS) with increased risk of differentiated thyroid cancer (DTC), but their role in mortality of patients has not been established. Also, no preoperative marker of the clinical outcome of thyroid cancer had yet been identified. The aim of the study was to investigate the relationship between the variants and overall mortality in patients with DTC. EXPERIMENTAL DESIGN: Retrospective study of 1,836 patients (1,643 women, 193 men) with median age at diagnosis of 49 years and overall median follow-up time of 8.7 years after initial treatment at a single comprehensive cancer center between 1990 and 2013. RESULTS: Among 5 variants, rs966423 was associated with increased mortality, which was 6.4% (33 of 518) versus 3.7% (47 of 1,259) in TT carriers versus CC/CT carriers (P = 0.017). The HR of TT versus TC/CC carriers was 1.6 [95% confidence interval (CI), 1.02-2.49; P = 0.038] after adjustment for age at diagnosis and sex. Importantly, the association of rs966423 with mortality remained valid when clinicopathologic risk factors were included in the model (HR, 1.89; 95% CI, 1.14-3.13; P = 0.014). Higher rs966423-associated patient mortality of TT versus CC/CT carriers was also observed in interaction with angioinvasion (adjusted HR, 3.48; 95% CI, 1.67-7.22; P < 0.001), lymph node metastasis (adjusted HR, 3.47; 95% CI, 1.16-10.4; P = 0.018), extrathyroidal invasion (adjusted HR, 2.07; 95% CI, 1.15-3.73; P = 0.013). CONCLUSIONS: The presence of the rs966423-TT genotype was associated with a significant increase in overall mortality of patients with DTC. Contrary to BRAF mutation and other somatic changes, the status of germline rs966423 is known before the treatment and might be used in the management of mortality risk by means of modification of therapy.

In-depth characterization of the microRNA transcriptome in normal thyroid and papillary thyroid carcinoma.

CONTEXT: A single microRNA gene may give rise to several mature products that differ in length, called isomiRs. IsomiRs are known to be tissue specific and functionally relevant. The microRNA sequence heterogeneity of the thyroid gland has yet to be determined. OBJECTIVE: The objective of the study was to provide a comprehensive view of the microRNA transcriptome in normal thyroid and papillary thyroid carcinoma (PTC). DESIGN: We used next-generation deep sequencing to analyze microRNA length heterogeneity and expression profiles of PTC tumors (n = 14), unaffected tissue adjacent to tumors (n = 14), and control, noncancerous thyroid tissue (n = 14). The results were validated with a microarray on an additional set of 9 PTC tumor/normal tissue pairs. RESULTS: Eighty-nine microRNAs were significantly deregulated in PTC compared with normal thyroid tissue (false discovery rate < 0.05, fold change 0.13-20.7). Top deregulated miRNAs included miR-146b-5p, miR-221-3p, miR-7-3p, miR-551b-3p, miR-486-3p, and miR-144-3p, confirming previous microarray profiling. The expression of miRNAs did not depend on the BRAF mutation status. Interestingly, 85% of the most abundant microRNAs consisted of isoforms that differed from the standard reference sequence deposited in miRBase. Moreover, the reference microRNAs were completely absent in 42.4% and 35.9% of the microRNAs expressed in normal thyroid and PTC tumors, respectively. Numerous isomiRs had altered seed sequences, which led to a different set of target genes. For highly deregulated miR-146b-5p, we detected 6 isoforms (tumor/normal fold change 14.4-28.7, false discovery rate < 0.002) that varied at their 5' ends with a 1-nt difference that created 2 alternative seeds. The target genes for those 2 seeds overlapped in only 13.1% of genes. CONCLUSIONS: Almost all microRNAs exhibit isoforms of variable length and potentially distinct function in thyroid tumorigenesis.

Cumulative risk impact of five genetic variants associated with papillary thyroid carcinoma.

BACKGROUND: Two recent genome-wide association studies (GWASs) identified five single nucleotide polymorphisms (SNPs; rs965513, rs944289, rs966423, rs2439302, and rs116909374) associated with papillary thyroid carcinoma (PTC). Each variant showed highly significant but moderate to low disease risk. Here we assessed the cumulative risk and predictive value of the five SNPs. METHODS: We genotyped two cohorts of individuals, 747 PTC cases and 1047 controls from Ohio and 1795 PTC cases and 2090 controls from Poland. Cumulative genetic risk scores were calculated using unweighted and weighted approaches. RESULTS: All five SNPs showed significant association with PTC. The average cumulative risk score in cases was significantly higher than in controls (p<2.2×10(-16)). Each additional risk allele increased the risk of having PTC by 1.51 [95% confidence interval (CI) 1.4, 1.64] in Ohio and by 1.35 [95% CI 1.27, 1.44] in Poland. An analysis was performed weighing risk alleles by effect size and assigning individuals to three weighted risk score groups, low (≤2), medium (2-5), and high (>5). Individuals in the high group were significantly more susceptible to PTC compared with individuals in the low group with an odds ratio of 8.7 [95% CI 5.8, 13.3] in Ohio and 4.24 [95% CI 3.10, 5.84] in Poland. Almost identical results were obtained when follicular variant PTCs and microPTCs were omitted. These five SNPs explained 11% of the familial risk of thyroid cancer in the Ohio cohort and 6% in the Polish cohort. CONCLUSION: As the genetic risk score increases, the risk of having PTC increases. However, the predictive power of the cumulative effect of these five variants is only moderately high and clinical use may not be feasible until more variants are detected.

Ultra-rare mutation in long-range enhancer predisposes to thyroid carcinoma with high penetrance.

Thyroid cancer shows high heritability but causative genes remain largely unknown. According to a common hypothesis the genetic predisposition to thyroid cancer is highly heterogeneous; being in part due to many different rare alleles. Here we used linkage analysis and targeted deep sequencing to detect a novel single-nucleotide mutation in chromosome 4q32 (4q32A>C) in a large pedigree displaying non-medullary thyroid carcinoma (NMTC). This mutation is generally ultra-rare; it was not found in 38 NMTC families, in 2676 sporadic NMTC cases or 2470 controls. The mutation is located in a long-range enhancer element whose ability to bind the transcription factors POU2F and YY1 is significantly impaired, with decreased activity in the presence of the C- allele compared with the wild type A-allele. An enhancer RNA (eRNA) is transcribed in thyroid tissue from this region and is greatly downregulated in NMTC tumors. We suggest that this is an example of an ultra-rare mutation predisposing to thyroid cancer with high penetrance.

SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility.

BACKGROUND: Papillary thyroid carcinoma (PTC) shows high heritability, yet efforts to find predisposing genes have been largely negative. OBJECTIVES: The objective of this study was to identify susceptibility genes for PTC. METHODS: A genome-wide linkage analysis was performed in 38 families. Targeted association study and screening were performed in 2 large cohorts of PTC patients and controls. Candidate DNA variants were tested in functional studies. RESULTS: Linkage analysis and association studies identified the Slit-Robo Rho GTPase activating protein 1 gene (SRGAP1) in the linkage peak as a candidate gene. Two missense variants, Q149H and A275T, localized in the Fes/CIP4 homology domain segregated with the disease in 1 family each. One missense variant, R617C, located in the RhoGAP domain occurred in 1 family. Biochemical assays demonstrated that the ability to inactivate CDC42, a key function of SRGAP1, was severely impaired by the Q149H and R617C variants. CONCLUSIONS: Our findings suggest that SRGAP1 is a candidate gene in PTC susceptibility. SRGAP1 is likely a low-penetrant gene, possibly of a modifier type.

Thyroid sialyltransferase mRNA level and activity are increased in Graves' disease.

Sialylation of cell components is an important immunomodulating mechanism affecting cell response to hormones and adhesion molecules. To study alterations in sialic acid metabolism in Graves' disease (GD) we measured the following parameters in various human thyroid tissues: lipid-bound sialic acid (LBSA) content, ganglioside profile, total sialyltransferase activity, and the two major sialyltransferase mRNAs for sialyltransferase-1 (ST6Gal I) and for sialyltransferase-4A (ST3Gal I). Fragments of toxic thyroid nodules (TN), nontoxic thyroid nodules (NN) and nontumorous tissue from patients with nodular goiter or thyroid cancer were used as a control (C). The LBSA content and sialyltransferase activity were the highest in the GD group (164 +/- 4.44 versus 120 +/- 2.00 nmoL/g, p = 0.005 and 1625 +/- 283.5 versus 324 +/- 54.2 cpm/mg of protein, p < 0.005 compared to control group C). Ganglioside profile in the GD group was similar to that in control tissues. Sialyltransferase- 1 mRNA and sialyltransferase-4A mRNA levels were significantly higher in the GD group than in the control group (12.52 +/- 6.90 versus 2.54 +/- 1.24 arbitrary units, p < 0.005 and 2,49 +/- 1.16 versus 1.23 +/- 0.46 arbitrary units, p < 0.05, respectively). There was a positive correlation between the increased sialyltransferase-1 mRNA level and the TSH-receptor antibody titer determined by the TRAK test. These results indicate that sialyltransferases expression and activity are increased in GD. Exact mechanism of this upregulation remains unknown, though one of possible explanations is the activation of the thyrotropin (TSH) receptor.