Normal Thyroid Tissue Specimens Research Articles

Validation of Reference Genes for Normalization of Relative qRT-PCR Studies in Papillary Thyroid Carcinoma

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) in thyroid tumors require accurate data normalization, however, there are no sufficient studies addressing the suitable reference genes for gene expression analysis in malignant and normal thyroid tissue specimens. The purpose of this study was to identify valid internal control genes for normalization of relative qRT-PCR studies in human papillary thyroid carcinoma tissue samples. The expression characteristics of 12 candidate reference genes (GAPDH, ACTB, HPRT1, TBP, B2M, PPIA, 18SrRNA, HMBS, GUSB, PGK1, RPLP0, and PGM1) were assessed by qRT-PCR in 45 thyroid tissue samples (15 papillary thyroid carcinoma, 15 paired normal tissues and 15 multinodular goiters). These twelve candidate reference genes were selected by a systematic literature search. GeNorm, NormFinder, and BestKeeper statistical algorithms were applied to determine the most stable reference genes. The three algorithms were in agreement in identifying GUSB and HPRT1 as the most stably expressed genes in all thyroid tumors investigated. According to the NormFinder software, the pair of genes including ‘GUSB and HPRT1’ or ‘GUSB and HMBS’ or ‘GUSB and PGM1’ were the best combinations for selection of pair reference genes. The optimal number of genes required for reliable normalization of qPCR data in thyroid tissues would be three according to calculations made by GeNorm algorithm. These results suggest that GUSB and HPRT1 are promising reference genes for normalization of relative qRT-PCR studies in papillary thyroid carcinoma.

Steroid receptor coactivator-1 interacts with NF-κB to increase VEGFC levels in human thyroid cancer.

Thyroid cancer is the most common endocrine cancer, and has a high incidence of lymphatic metastasis. Vascular endothelial growth factor C (VEGFC) is essential for development of lymphatic vessels and lymphatic metastases during carcinogenesis. Steroid receptor coactivator-1 (SRC-1) interacts with nuclear receptors and transcription factors to promote tumor proliferation and metastasis. However, the correlation between SRC-1 and VEGFC levels in the lymphatic metastases of thyroid cancer remains unclear. We analyzed 20-paired specimens of thyroid cancer tissue and normal thyroid tissue and found increased levels of SRC-1 and VEGFC proteins in 13/20 and 15/20 thyroid cancer specimens, respectively, when compared with those levels in specimens of normal thyroid tissue. A high level of SRC-1 expression was positively correlated with VEGFC and lymphatic endothelial cell marker LYVE-1 expression. Papillary thyroid carcinoma cell line TPC-1 displayed high levels of SRC-1 and VEGFC expression and was selected for stable knockdown of SRC-1 in vitro. Inhibition of SRC-1 significantly reduced the VEGFC levels in TPC-1 cells. We found that SRC-1 binds to transcription factor NF-kB (p50/p65), and that this coactivation complex directly promoted VEGFC transcription, which could be abrogated by SRC-1 knockdown. Up-regulated NF-kB signaling was also confirmed in thyroid cancer tissues. In vivo studies showed that SRC-1 knockdown restricted tumor growth, reduced the numbers of LYVE-1-positive lymphatic vessels, and decreased the levels of VEGFC in tumor tissues. These results suggest a tumorigenic role for SRC-1 in thyroid cancer via its ability to regulate VEGFC expression.

Expression and clinical significance of tyrosine phosphatase SHP2 in thyroid carcinoma.

Protein-tyrosine phosphatase SHP2 is encoded by the gene PTPN11. SHP2 is hypothesized to have a critical role in cancer, via the activation of mutations that have been detected in several types of leukaemia and in certain solid tumours, including liver, breast, gastric and cervical cancer. However, to the best of our knowledge, there have been no previous reports evaluating the significance of SHP2 expression in thyroid cancer. The present study evaluated SHP2 expression in 65 thyroid cancer specimens, 40 specimens of self-matched adjacent peritumour tissues and 40 specimens of normal thyroid tissue, using immunohistochemical and western blot analyses with an anti-SHP2 antibody. Western blotting was also used to assess SHP2 expression in thyroid cancer cell lines (SW579, IHH-4, FTC-133, TPC-1, DRO, TA-K, and ML-1) and Nthy-ori3-1 normal thyroid cells. In addition, SHP2 antisense oligonucleotides were used to block SHP2 expression in SW579 cells, and growth inhibition assays were conducted. Increased SHP2 expression was detected in the tumour tissues compared with that of the normal thyroid tissues (P<0.05). SHP2 expression was significantly correlated with poor tumour differentiation (P<0.05), late TNM stage (P<0.05) and lymph node metastasis (P<0.05), suggesting that SHP2 may represent a potential target for thyroid cancer therapy.

Investigation of BK virus, Epstein-Barr virus and human papillomavirus sequences in postoperative thyroid gland specimens.

Although recent evidence has implicated viruses in the regulation of epithelial-to-mesenchymal transition and tumor progression, little is known regarding viral infections in thyroid malignancies. Thus the aim of this study was to detect sequences of 3 potentially oncogenic viruses - BK virus (BKV), Epstein-Barr virus (EBV) and human papillomavirus (HPV) - in a series of postoperative thyroid gland specimens. Thirty patients with thyroid nodules who underwent surgery for thyroid disease within a 3-year period were enrolled. Both nodular and adjacent normal thyroid tissue was surgically excised from each patient. Viral gene sequences of BKV (VP1), EBV (LMP1, EBNA2 and EBER1) and HPV were amplified by PCR. The PCR results were confirmed by direct sequencing analysis. VP1 gene sequences were detected in 60% (18/30) of thyroid cancer or multinodular hyperplasia lesions compared with in 43.3% (13/30) of adjacent normal thyroid tissue specimens. Fifteen of thirty (50%) of thyroid cancer or multinodular hyperplasia samples revealed LMP1 sequences compared with 46.7% (14/30) of corresponding normal thyroid tissues. EBNA2 gene sequences were detected in 90% (27/30) of thyroid cancer or multinodular hyperplasia samples, compared with 90% (27/30) of adjacent normal thyroid tissue specimens. All samples were negative for EBER1 sequences, while HPV DNA was not detected in either nodular or normal thyroid tissue. This study suggests that BKV and EBV "infection" is an early event, occurring within normal tissue. Our findings do not show a clear role for the viruses examined, instead they suggest an "endemicity" pattern rather than a causal effect.

MiR-219-5p modulates cell growth of papillary thyroid carcinoma by targeting estrogen receptor α.

Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy. It has been demonstrated that micro-RNAs (miRNAs) are involved in the development of PTC. The miRNA-chromatin immunoprecipitation microarray assay revealed down-regulation of miR-219-5p; however, the effect of miR-219-5p on PTC cell growth remains unknown. This result implied the critical role of miR-219-5p in the development of PTC. We investigated the association between miR-219-5p and PTC development. Expression of miR-219-5p was monitored in 30 PTC tissue specimens and compared with that in 30 normal thyroid tissue specimens. The effect of miR-219-5p on PTC development was studied by cell proliferation, migration, and apoptosis assays. The underlying mechanism was clarified by a reporter assay and rescue experiment. The current study confirmed that miR-219-5p expression was inhibited in PTC tissue samples. There were statistically significant differences in the expression of miR-219-5p with regard to sex, tumor size, and lymph node metastasis in patients with PTC. Forced expression of miR-219-5p suppressed PTC cell proliferation and migration and promoted apoptosis. Further study showed that estrogen receptor (ER) α was the direct target of miR-219-5p and mediated the effect of miR-219-5p on PTC occurrence. Expression of miR-219-5p was inversely correlated with that of ERα. Importantly, ERα overexpression in PTC cells rescued the inhibitory effect of miR-219-5p on PTC cell proliferation and migration. Thus, our results indicated that miR-219-5p played a critical role in PTC growth by inhibiting ERα. Our investigation identified miR-219-5p as a negative regulator of PTC development through targeting of ERα.

Up-regulation of nuclear receptor coactivator amplified in breast cancer-1 in papillary thyroid carcinoma correlates with lymph node metastasis

Nuclear receptor coactivator amplified in breast cancer-1 (AIB1), a new oncogenic coactivator, is commonly overexpressed and amplified in variety of human cancers. However, the expression of AIB1 in papillary thyroid carcinoma (PTC), the major histologic type of thyroid cancer, and its clinical significance are still unclear. AIB1 expression in PTC was examined by immunohistochemistry using tissue microarrays comprised of 90 primary PTC, 46 matched lymph node, and 20 normal thyroid tissue specimens in this study. In the normal thyroid specimens, AIB1 expression was either absent or at low levels. In contrast, AIB1 overexpression was detected in 50 of 83 (60.2 %) primary PTC specimens. Up-regulated AIB1 was evident in 39 of 46 (73.5 %) matched lymph nodes. Overexpression of AIB1 was observed more frequently in PTCs with lymph node metastasis [N1a/N1b, 39/46 (73.5 %)] versus PTCs without lymph node metastasis [N0, 14/34 (41.2 %)]. Furthermore, high-level AIB1 expression was only observed in the lymph node-positive specimens. Moreover, we found no correlation between AIB1 expression and ER expression in PTC tissues. Our findings suggest that overexpression of AIB1 may be a biomarker for tumorigenesis and progression of PTC and may play an important role in its acquisition of a metastatic phenotype.

Overexpression of HIF-2α, TWIST, and CXCR4 Is Associated with Lymph Node Metastasis in Papillary Thyroid Carcinoma

This study aimed to examine HIF-2α, TWIST, and CXCR4 expression in papillary thyroid carcinoma (PTC) and assesses the association of their expression with clinicopathological indicators. HIF-2α, TWIST, and CXCR4 protein expression in 129 PTCs, 61 nodular hyperplasia, and 118 normal thyroid tissue specimens was analyzed using immunohistochemistry. The protein expression levels of these three molecules were upregulated in PTCs. High protein expression of HIF-2α, TWIST, and CXCR4 was significantly correlated with lymph node metastasis (LNM) (P < 0.001). Furthermore, HIF-2α, TWIST, and CXCR4 protein expression was correlated with one another. Concomitant high expression of these molecules had stronger correlation with LNM than did each alone (P = 0.032 for HIF-2α/TWIST, P < 0.001 for HIF-2α/CXCR4, P = 0.018 for TWIST/CXCR4, and P < 0.001 for HIF-2α/TWIST/CXCR4). Additionally, HIF-2α, TWIST, and CXCR4 mRNA expression were assessed in 30 PTCs, 10 nodular hyperplasia, and 10 normal thyroid tissue specimens using real-time RT-PCR. TWIST and CXCR4 mRNA expression levels were up-regulated in PTCs, and high mRNA expression of TWIST and CXCR4 was significantly correlated with LNM (P = 0.005 and P = 0.010, resp.). These results demonstrated that the evaluation of HIF-2α, TWIST, and CXCR4 expression in PTC may be useful in predicting the risk of LNM.

Differential gene expression profiling of aggressive and nonaggressive follicular carcinomas

The classification of follicular thyroid neoplasms requires surgical resection for histologic evaluation of malignancy. Because variable clinical behavior exists, genomic expression profiling may lead to the identification of novel markers that facilitate better biologic classification. We performed for the first time gene expression analysis on clinically aggressive and nonaggressive follicular carcinomas (FCs) from patients for whom long-term follow-up data were available. We examined matched fresh-frozen tissue from 15 histopathologically diagnosed follicular carcinomas (7 patients with documented distant metastasis and/or death from disease and 8 patients without recurrence). For categorical comparison, we analyzed 4 follicular adenomas (FAs). The biologic control comprised 11 normal thyroid tissue specimens. High-quality RNA was extracted from the tissues, labeled, and hybridized to an Affymetrix (Santa Clara, CA) oligonucleotide microarray (HG-U133A). With the exceptions of 1 follicular adenoma and 1 follicular carcinoma, unsupervised hierarchical cluster analysis revealed 2 distinct groups--one containing normal thyroid tissue and follicular adenomas and another containing follicular carcinomas. We identified 421 genes that were differentially expressed between histologically normal thyroid tissues and all follicular neoplasms (P < 0.01; fold-change >2), 94 genes that distinguished follicular carcinomas from follicular adenomas (including PBP and CKS2), and 4 genes that distinguished aggressive follicular carcinomas from nonaggressive follicular carcinomas (NID2, TM7SF2, TRIM2, and GLTSCR2). Comparative genomic groupings identified differentially expressed genes that may lead to better classification of follicular thyroid neoplasms. Such genes may be used in future prospective validation studies to establish clinically useful and complementary diagnostic markers.

Expression of bcl-2 in Papillary Thyroid Cancers and its Prognostic Value

Purpose: Papillary thyroid cancer has a good prognosis. This favourable prognosis may be attributed to the apoptotic tendency of the cancer cells. This study aims to evaluate the expression of bcl-2, which is an antidote of apoptosis, and aims to evaluate the value of bcl-2 as a prognostic marker in papillary thyroid cancer. Material-Methods : Bcl-2 expression in the archival materials of 31 patients with papillary thyroid cancer was examined with immunohistochemical methods using bcl-2 and p-53 stains. The results were compared with 31 normal thyroid tissue specimens, which consisted of the contralateral lobes of these patients. The results were then analyzed in accordance with the clinical features of the patients.Results : Thirty (96.7%) patients of the control group were positive for bcl-2 whilst one (3.3%) was negative. The staining for bcl-2 was positive in 12 (%75) patients with microcarcinomas (p < 0.05) and 13 (86.6%) with papillary cancers (p > 0.05). Two cases of the papillary cancer group were admitted to the hospital with local recurrence (6.4%) and both were positive for bcl-2 (p > 0.05). All cases (4/31), whose MACIS scores were higher than 7 were positive for bcl-2. Twenty-one of 27 cases whose MACIS scores were lower than 7 (77.7%) were positive for bcl-2 (p > 0.05). All tumours of this series were negative for p-53 immunstaining.Conclusion : The rate of bcl-2 expression in microcarcinomas of papillary thyroid cancer decreases when compared to normal thyroid tissue. This may be an early sign of oncogenesis, and a reason for the favourable prognosis in microcarcinomas. However, bcl-2 cannot be used as a prognostic marker.

Telomere shortening with aging in human thyroid and parathyroid tissue

Progressive telomere shortening with aging was studied using normal thyroid tissue specimens from 46 human subjects aged between 0 and 98yr and normal parathyroid tissue specimens from 21 human subjects aged between 0 and 83yrs. There has hitherto been no information documented about telomere length in such thyroid and parathyroid tissues. Age-related shortening at rates of 91 and 92base pairs (bp) per year, respectively, were observed. Telomere lengths of normal thyroid tissues were 16.53±1.10 (mean±SE), 14.31±0.80, 11.27±0.68 and 8.73±1.08kbp for age groups less than 2, 20–50, 51–80 and more than 80yr. Telomere lengths of normal parathyroid tissues were 15.80±1.46 (mean±SE), 15.36±0.86 and 10.93±0.78kbp for age groups less than 4, 20–50 and 51–80yr. Telomere shortening occurred after 50yr of age in thyroid and parathyroid tissues. Human thyroid and parathyroid tissues do not seem to show the rapid reduction in telomere length early in life that was reported for some human cell types, suggesting that the rate of telomere shortening has tissue-specific characteristics.

Expression of RET and its ligand complexes, GDNF/GFRalpha-1 and NTN/GFRalpha-2, in medullary thyroid carcinomas.

Mutations in the RET proto-oncogene are found in about one third of sporadic medullary thyroid carcinomas (MTCs), mostly affecting codon 918. Glial cell line derived neurotropic factor (GDNF) and its membrane-bound GDNF family receptor alpha (GFRalpha-1), as well as neurturin (NTN) and its membrane-bound receptor GFRalpha-2 form a complex with the RET product, a receptor tyrosine kinase, resulting in downstream signaling to the nucleus. To elucidate the role of these RET ligands in MTC tumorigenesis, their expression was determined in 15 MTC samples, one papillary thyroid carcinoma (PTC) and three normal thyroid tissue specimens. The mRNA expression of RET, GDNF, GFRalpha-1, NTN and GFRalpha-2 was investigated by mRNA in situ hybridization, and confirmed by reverse transcription-PCR analysis. None of the five genes was expressed in the normal thyroids or in the PTC. All MTCs showed expression of RET, 13 expressed GDNF, 12 expressed GFRalpha-1 and 9 expressed NTN and GFRalpha-2. In 7 of the tumors RET, GDNF and GFRalpha-1 were expressed at high levels, and in five of these seven tumors NTN and GFRalpha-2 genes were also expressed at high levels. The high level of expression was preferentially seen in tumor cells adjacent to stroma and connective tissue. All MTCs without expression of the RET ligands harbored the RET codon 918 mutation. The results suggest that this signaling pathway is important for MTC development, and that it may be activated by expression of the RET ligand complexes by the tumor cells themselves.

Type IV collagenase and immunostaining of type IV collagen in human thyroid tumors

Objective: Required stages in the processes of malignant tumor invasion and metastasis are known to include the destruction of cell stroma and vascular basement membrane. It has been suggested that type IV collagenase can degrade type IV collagen, a main component of basement membrane. In our study, type IV collagenase activity was compared with the grade of destruction of type IV collagen by thyroid tumors. Methods: Type IV collagenase activity was measured in human thyroid tissue obtained surgically from four patients with Graves’ disease, four with follicular adenoma, six with papillary carcinoma, and four with follicular carcinoma. Six normal thyroid tissue specimens were also studied. The grade of destruction in the diseased regions of thyroid tumors and surrounding intact tissues were determined immunochemically by anti-type IV collagen antibody staining. Results: Tumors with high type IV collagenase activity exhibited extracapsular invasion, lymph node metastasis and very weak discontinuity of immunostaining for type IV collagen from the basement membrane in diseased regions. In addition, surrounding intact tissues exhibited weak immunostaining for type IV collagen. Tumors with low type IV collagenase activity exhibited neither extracapsular invasion nor lymph node metastasis, but did exhibit weak immunostaining for type IV collagen from the basement membranes in diseased regions. However, the surrounding intact tissues had preserved type IV collagen in follicular basement membranes. Conclusion: These findings suggest that staining for type IV collagen can be considered a biochemical marker for prediction of the aggressiveness of invasion and metastasis.

Functional insulin receptors are overexpressed in thyroid tumors: is this an early event in thyroid tumorigenesis?

Insulin receptor (IR), a member of the receptor tyrosine kinase family, is expressed in normal thyroid cells and affects thyroid cell proliferation and differentiation. The authors measured IR content in benign and malignant thyroid tumors by three independent methods: a specific radioimmunoassay, 125I-insulin binding studies, and immunohistochemistry. The results obtained were compared with the IR content in paired, adjacent, normal thyroid tissue. To assess IR function in thyroid carcinoma cells, glucose uptake responsiveness to insulin was also studied in a human transformed thyroid cell line (B-CPAP) and in follicular carcinoma cells in primary culture. In 9 toxic adenomas, the average IR content was similar to that observed in the 9 paired normal thyroid tissue specimens from the same patients (2.2+/-0.3 vs. 2.1+/-0.3). In 13 benign nonfunctioning, or "cold," adenomas, the average IR content was significantly higher (P < 0.001) than in paired normal tissue specimens (4.3+/-0.5 vs. 1.8+/-0.1). In 12 papillary and 10 follicular carcinomas, IR content was significantly higher (P < 0.001) than in the adjacent normal thyroid tissue (4.0+/-0.4 vs. 1.6+/-0.2 and 5.6+/-1.0 vs. 1.8+/-0.2, respectively). The finding of a higher IR content in benign "cold" adenomas and in thyroid carcinomas was confirmed by both binding and immunostaining studies. The current studies indicate that 1) IR content is elevated in most follicular and papillary differentiated thyroid carcinomas, and 2) IR content is also elevated in most benign follicular adenomas ("cold" nodules) but not in highly differentiated, hyperfunctioning follicular adenomas ("hot" nodules), which very rarely become malignant. This observation suggests that increased IR expression is not restricted to the thyroid malignant phenotype but is already present in the premalignant "cold" adenomas. It may contribute, therefore, to thyroid tumorigenesis and/or represent an early event that gives a selective growth advantage to transformed thyroid cells.

Increased expression of the Na+/I- symporter in cultured human thyroid cells exposed to thyrotropin and in Graves' thyroid tissue.

The Na+/I- symporter (NIS) is important in hormone synthesis in the thyroid gland. NIS activity, as reflected by I- uptake, was increased by TSH (1 mU/mL) or forskolin (10 mumol/L) in primary cultured human thyroid cells. Northern blot analysis revealed that incubation of these cells with TSH or forskolin for 24 h increased the abundance of NIS messenger ribonucleic acid (mRNA) 2.3- and 2.5-fold, respectively. Immunoblot analysis revealed 2.7- and 2.4-fold increases, respectively, in the amount of NIS protein after 48 h, suggesting that elevated levels of intracellular cAMP induced the expression of NIS in human thyrocytes. We then studied the levels of NIS mRNA and protein in Graves' thyroid tissue and found that the amount of NIS mRNA in thyroid tissue from individuals with Graves' disease (n = 5) was 3.8 times that in normal thyroid tissue (n = 5). The abundance of NIS mRNA was significantly correlated with that of thyroid peroxidase or thyroglobulin mRNAs, but not with that of TSH receptor mRNA, in the Graves' and normal thyroid tissue specimens. The amount of NIS protein was also increased 3.1-fold in Graves' thyroid tissue compared with that in normal thyroid tissue. The increased expression of NIS may thus contribute to the development of Graves' disease.

Proteolytic activity of thyroid enzymes in endemic goiter.

ABSTRACT The efficiency of the intrathyroid proteolytic system was studied in 17 subjects living in the endemic goiter region of the Uele (Republic of Congo). A thyroid extract containing the proteolytic enzymes and the thyroglobulin was prepared and incubated either alone or in the presence of hemoglobin at 37 C and pH 3.5 for various periods of time. All the thyroid extracts have a proteolytic action. This action, however, is inferior to that of specimens of normal thyroid tissue taken from man or sheep. These results suggest the existence of an insufficient proteolysis of the thyroglobulin in endemic goiter.