Malgorzata Czetwertynska

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.

Variants in the ATM-CHEK2-BRCA1 Axis Determine Genetic Predisposition and Clinical Presentation of Papillary Thyroid Carcinoma

The risk of developing papillary thyroid carcinoma (PTC), the most frequent form of thyroid malignancy, is elevated up to 8.6‐fold in first‐degree relatives of PTC patients. The familial risk could be explained by high‐penetrance mutations in yet unidentified genes, or polygenic action of low‐penetrance alleles. Since the DNA‐damaging exposure to ionizing radiation is a known risk factor for thyroid cancer, polymorphisms in DNA repair genes are likely to affect this risk. In a search for low‐penetrance susceptibility alleles we employed Sequenom technology to genotype deleterious polymorphisms in ATM, CHEK2, and BRCA1 in 1,781 PTC patients and 2,081 healthy controls. As a result of the study, we identified CHEK2 rs17879961 (OR = 2.2, P = 2.37e‐10) and BRCA1 rs16941 (odds ratio [OR] = 1.16, P = 0.005) as risk alleles for PTC. The ATM rs1801516 variant modifies the risk associated with the BRCA1 variant by 0.78 (P = 0.02). Both the ATM and BRCA1 variants modify the impact of male gender on clinical variables: T status (P = 0.007), N status (P = 0.05), and stage (P = 0.035). Our findings implicate an important role of variants in the ATM‐ CHEK2‐ BRCA1 axis in modification of the genetic predisposition to PTC and its clinical manifestations.

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.

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. Clin Cancer Res; 22(5); 1111–9. ©2015 AACR.

The rs2910164 Genetic Variant of miR-146a-3p Is Associated with Increased Overall Mortality in Patients with Follicular Variant Papillary Thyroid Carcinoma

Aberrant expression of the sodium-iodide symporter (NIS) and the resistance to post-operative radioactive iodide treatment is a crucial cause of higher mortality of some thyroid cancer patients. In this study, we analyzed the impact of miR-146a on the expression and function of NIS and on the overall survival of thyroid cancer patients. The study included 2441 patients (2163 women; 278 men); including 359 cases with follicular variant of papillary thyroid carcinoma (fvPTC). miR:NIS interactions were analyzed in cell lines using in vivo binding and inhibition assays and radioactive iodine uptake assays. Tumor/blood DNA was used for rs2910164 genotyping. Overall survival was assessed retrospectively. In the results, we showed that miR-146a-3p directly binds to and inhibits NIS. Inhibition of miR-146a-3p restores the expression and function of NIS, increasing radioactive iodine uptake. Rs2910164 functional variant within miR-146a-3p is associated with increased overall mortality among fvPTC female patients. The deaths per 1000 person-years were 29.7 in CC carriers vs. 5.08 in GG/GC-carriers (HR = 6.21, p = 0.006). Higher mortality of CC vs. GG/GC carriers was also observed in patients with lower clinical stage (HR = 22.72, p < 0.001), smaller tumor size (pT1/pT2) (HR = 25.05, p < 0.001), lack of extrathyroidal invasion (HR = 9.03, p = 0.02), lack of nodular invasion (HR = 7.84, p = 0.002), lack of metastases (HR = 6.5, p = 0.005) and older (age at diagnosis >50 years) (HR = 7.8, p = 0.002). MiR-146a-3p underwent somatic mutations in 16.1% of analyzed specimens, mainly towards the deleterious C allele. In this report we propose a novel molecular marker of the clinical outcome of fvPTC patients. Rs2910164 increases the overall mortality with inhibition of NIS and disruption of radioiodine uptake as a possible mechanism.

Correction: Ultra-Rare Mutation in Long-Range Enhancer Predisposes to Thyroid Carcinoma with High Penetrance

An additional grant from the National Cancer Institute was incorrectly omitted from the Funding Statement. The number of the grant is: R01 CA151979.