Genetic relationship between Hashimoto`s thyroiditis and papillary thyroid carcinoma with coexisting Hashimoto`s thyroiditis.

Hashimoto's thyroiditis (HT) is present in the background of around 30% of papillary thyroid carcinomas (PTCs). The genetic predisposition effect of this autoimmune condition is not thoroughly understood. We analyzed the microarray expression profiles of 13 HT, eight PTCs with (w/) coexisting HT, six PTCs without (w/o) coexisting HT, six micro PTCs (mPTCs), and three normal thyroid (TN) samples. Based on a false discovery rate (FDR)-adjusted p-value ≤ 0.05 and a fold change (FC) > 2, four comparison groups were defined, which were HT vs. TN; PTC w/ HT vs. TN; PTC w/o HT vs. TN; and mPTC vs. TN. A Venn diagram displayed 15 different intersecting and non-intersecting differentially expressed gene (DEG) sets, of which a set of 71 DEGs, shared between the two comparison groups HT vs. TN ∩ PTC w/ HT vs. TN, harbored the relatively largest number of genes related to immune and inflammatory functions; oxidative stress and reactive oxygen species (ROS); DNA damage and DNA repair; cell cycle; and apoptosis. The majority of the 71 DEGs were upregulated and the most upregulated DEGs included a number of immunoglobulin kappa variable genes, and other immune-related genes, e.g., CD86 molecule (CD86), interleukin 2 receptor gamma (IL2RG), and interferon, alpha-inducible protein 6 (IFI6). Upregulated genes preferentially associated with other gene ontologies (GO) were, e.g., STAT1, MMP9, TOP2A, and BRCA2. Biofunctional analysis revealed pathways related to immunogenic functions. Further data analysis focused on the set of non-intersecting 358 DEGs derived from the comparison group of HT vs. TN, and on the set of 950 DEGs from the intersection of all four comparison groups. In conclusion, this study indicates that, besides immune/inflammation-related genes, also genes associated with oxidative stress, ROS, DNA damage, DNA repair, cell cycle, and apoptosis are comparably more deregulated in a data set shared between HT and PTC w/ HT. These findings are compatible with the conception of a genetic sequence where chronic inflammatory response is accompanied by deregulation of genes and biofunctions associated with oncogenic transformation. The generated data set may serve as a source for identifying candidate genes and biomarkers that are practical for clinical application.

Comprehensive survey of HRAS, KRAS, and NRAS mutations in proliferative thyroid lesions from an ethnically diverse population.

BACKGROUND: The distribution and kind of rat sarcoma viral oncogenes homolog (RAS) mutations, as well as their clinical impact on different types of thyroid lesions, vary widely among the different populations studied. We performed a comprehensive mutational survey in the highly related RAS genes HRAS, KRAS, and NRAS in a case series of proliferative thyroid lesions with known BRAF mutational status, originating from an ethnically diverse group. MATERIALS AND METHODS: Mutational hotspot regions encompassing codons 12, 13, and 61 of the RAS genes were directly sequenced in 381 cases of thyroid lesions. In addition, the putative NRAS hotspot region encompassing codon 97 was sequenced in 36 thyroid lesions. The case series included lesions of Hashimoto's thyroiditis (HT), nodular goiters, hyperplastic nodules, follicular adenomas (FAs), Hurthle cell variants of FA, papillary thyroid carcinomas (PTCs), follicular variants of PTC (FVPTCs), microcarcinomas of PTC (micro PTCs; tumor size ≤1 cm), follicular TCs (FTCs), Hurthle cell variants of FTC, and non-well-differentiated TCs (NWDTCs). RESULTS: We identified RAS mutations in 16 out of 57 (28.1%) FAs, 2 out of 8 (25%) NWDTCs, 8 out of 42 (19.0%) FVPTCs, 2 out of 10 (20.0%) FTCs, 1 out of 12 (8.3%) Hurthle cell variants of FA, 3 out of 46 (6.5%) goiters, 1 out of 18 (5.6%) hyperplastic nodules, 3 out of 56 (5.4%) micro PTCs, 2 out of 115 (1.7%) PTCs, 0 out of 7 (0%) Hurthle cell variants of FTC, and 0 out of 10 (0%) HT lesions. NRAS codon 61 mutation was the predominant form, followed by HRAS codon 61 mutation. Only three mutations affected RAS codons 12 and 13, two of which were identified in goiters. No codon 97 mutation was detected in the examined FVPTCs. An as yet undescribed deletion of KRAS codon 59 was identified in one FA. DISCUSSION: RAS mutations in our case series were commonly associated with follicular-patterned thyroid lesions. Our data suggest that FAs with a RAS mutation may constitute precursor lesions for TC with follicular histology. The newly-discovered KRAS codon 59 deletion is one of the first reported codon deletions in a RAS hotspot region.

BRAF mutations in thyroid tumors from an ethnically diverse group.

BACKGROUND: The molecular etiology of thyroid carcinoma (TC) and other thyroid diseases which may present malignant precursor lesions is not fully explored yet. The purpose of this study was to estimate frequency, type and clinicopathological value of BRAF exon 15 mutations in different types of cancerous and non-cancerous thyroid lesions originating in an ethnically diverse population. METHODS: BRAF exon 15 was sequenced in 381 cases of thyroid lesions including Hashimoto´s thyroiditis, nodular goiters, hyperplastic nodules, follicular adenomas (FA), papillary TC (PTC), follicular variant PTC (FVPTC), microcarcinomas of PTC (micro PTC; tumor size ≤ 1 cm), follicular TC (FTC), and non-well differentiated TC (non-WDTC). RESULTS: We identified BRAF mutations in one of 69 FA, 72 of 115 (63%) PTC, seven of 42 (17%) FVPTC, 10 of 56 (18%) micro PTC, one of 17 (6%) FTC, and one of eight (13%) non-WDTC. Most of the cases showed the common V600E mutation. One case each of PTC, FVPTC, and FTC harbored a K601E mutation. A novel BRAF mutation was identified in a FA leading to deletion of threonine at codon 599 (p.T599del). A rare 3-base pair insertion was detected in a stage III PTC resulting in duplication of threonine at codon 599 (p.T599dup). Patients with PTC harboring no BRAF mutation (BRAFwt) were on average younger than those with a BRAF mutation (BRAFmut) in the PTC (36.6 years vs. 43.8 years). Older age (≥ 45 years) in patients with PTC was significantly associated with tumor size ≥ 4 cm (P = 0.018), vessel invasion (P = 0.004), and distant metastasis (P = 0.001). Lymph node (LN) involvement in PTC significantly correlated with tumor size (P = 0.044), and vessel invasion (P = 0.013). Of notice, taken the whole TC group, family history of thyroid disease positively correlated with capsular invasion (P = 0.025). CONCLUSIONS: Older age is manifold associated with unfavorable tumor markers in our series. The K601E identified in a PTC, FVPTC, and FTC seems to be more distributed among different histological types of TC than previously thought. The T599del is a yet undescribed mutation and the rare T599dup has not been reported as a mutation in PTC so far.