Inactivation of the hyperparathyroidism–jaw tumour syndrome (HPT– JT) gene, HRPT2, was recently established as a genetic mechanism in the development of parathyroid tumours. Its encoded protein parafibromin has tumour-suppressor properties that play an important role in tumour development in the parathyroids, jaws and kidneys. Inactivating HRPT2 mutations are common in HPT– JT and parathyroid carcinomas, and have been described in a few cases of parathyroid adenomas with cystic features. In this study, 46 cases of cystic parathyroid adenomas previously investigated for HRPT2 mutations were characterized with regard to MEN1 gene mutations, cyclin D1 expression and parafibromin expression. In normal tissues and cell lines, parafibromin was ubiquitously expressed. Furthermore, parafibromin was detected as a dominating nuclear and a weaker cytoplasmic signal in transfected cell lines. In the three parathyroid tumours with inactivating HRPT2 mutations parafibromin expression was not detectable, and in one of two cases with aberrantly sized parafibromin the protein was delocalized. Both high and low cyclin D1 levels were found among HRPT2-mutated and -unmutated tumours, suggesting that these events are not mutually exclusive in parathyroid tumour development. The presented data suggest that in the majority of benign parathyroid tumours the expression of parafibromin remains unaltered, while the loss of parafibromin expression is strongly indicative of gene inactivation through mutation of the HRPT2 gene.
C Juhlin, C Larsson, T Yakoleva, I Leibiger, B Leibiger, A Alimov, G Weber, A Höög, and A Villablanca
S Takahashi, M Hakuta, K Aiba, Y Ito, N Horikoshi, M Miura, K Hatake, and E Ogata
Parathyroid hormone (PTH) and PTH-related protein/peptide (PTHrP) bind to the same PTH/PTHrP receptor and stimulate osteoblasts to secrete pro-inflammatory cytokines like interleukin (IL)-6. In patients with primary hyperparathyroidism, elevation of plasma levels of tumor necrosis factor (TNF)-alpha and IL-6 was also described. We, therefore, postulated that PTHrP secreted from cancer cells stimulates the secretion of cytokines and causes increases in their blood levels. Blood concentrations of several cytokines (TNF-alpha, IL-1beta, IL-5, IL-6, IL-8, IL-11 and IL-12) in cancer-bearing patients with or without elevation of blood PTHrP were measured by ELISA. The patients with high plasma PTHrP levels (n=29, intact PTHrP: 8.5 +/- 1.4 pmol/l, normal: <1.1) had higher serum type 1 collagen C-telopeptide (ICTP). Twenty of the patients were hypercalcemic. Plasma concentrations of TNF-alpha, IL-6 and IL-8 were significantly increased in patients with high PTHrP, in either the presence or absence of hypercalcemia. The concentrations of TNF-alpha and IL-6 were also significantly correlated with those of PTHrP. Our observations indicate that high plasma levels of PTHrP in cancer-bearing patients contribute not only to the development of hypercalcemia, but also to the development of the syndrome caused by an excess of pro-inflammatory cytokines.
C C Juhlin, A Villablanca, K Sandelin, F Haglund, J Nordenström, L Forsberg, R Bränström, T Obara, A Arnold, C Larsson, and A Höög
Parafibromin is a protein product derived from the hyperparathyroidism 2(HRPT2) tumor suppressor geneand its inactivation has been coupled to familial and sporadic forms of parathyroid malignancy. In this study, we have conducted immunohistochemistry on 33 parathyroid carcinomas (22 unequivocal and 11 equivocal) using four parafibromin antibodies directed to different parts of the protein. Furthermore, for a fraction of cases, the immunohistochemical results were compared with known HRPT2 mutational status. Our findings show that 68% (15 out of 22) of the unequivocal carcinomas exhibited reduced expression of parafibromin while the 25 sporadic adenomas used as controls were entirely positive for parafibromin expression. Additionally, three out of the six carcinomas with known HRPT2 mutations showed reduced expression of parafibromin. Using all four antibodies, comparable results were obtained on the cellular level in individual tumors suggesting that there exists no epitope of choice in parafibromin immunohistochemistry. The results agree with the demonstration of a ~60 kDa product preferentially in the nuclear fraction by western blot analysis. We conclude that parafibromin immunohistochemistry could be used as an additional marker for parathyroid tumor classification, where positive samples have low risk of malignancy, whereas samples with reduced expression could be either carcinomas or rare cases of adenomas likely carrying an HRPT2 mutation.
F Lumachi, P Zucchetta, S Varotto, F Polistina, G Favia, and D D'Amico
In primary hyperparathyroidism (pHPT), parathyroidectomy is the treatment of choice, but anatomic variations of ectopic glands may cause surgical failure. Reliable preoperative noninvasive localization procedures would have a positive impact on the operative time and increase recovery rate. We retrospectively evaluated 186 patients with pHPT who were studied before successful parathyroidectomy by double tracer scintigraphy (99mTc-pertechnetate+201TI chloride or 99mTc-pertechnetate +99mTc-sestamibi, 160 patients), ultrasonography (148 patients) and computerized tomography (CT) scan (92 patients). During bilateral neck exploration, 159 (85.5%) single adenomas, 6 (3.2%) parathyroid carcinomas, and 3 (1.6%) double adenomas were found. Moreover, 18 (9.7%) patients had diffuse chief cells parathyroid hyperplasia. Removed parathyroid glands were in ectopic sites in 41 (22.0%) cases, mainly localized in the upper mediastinum or behind the esophagus. The overall sensitivity was 83.5 and 85.2% for 99mTc-pertechnetate+201TI chloride and 99mTc-pertechnetate+99mTc-sestamibi scintigraphy respectively, 80.4% for CT scan and 81.1% for ultrasonography. In patients with ectopic glands, sensitivity was 81.2, 79.5, 73.3 and 81.6% respectively. In 36 out of 41 patients with ectopic glands in whom the removed parathyroids were correctly localized, mean operative time was 95 min, and in 5 patients without preoperative localization it was 260 min. In conclusion, in pHPT, preoperative localization of an enlarged parathyroid is helpful, especially in ectopic adenomas and in anatomic variations in location, and it has been proved to reduce operative time and morbidity rate.
Pedro Weslley Rosario and Gabriela Franco Mourão
Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is an encapsulated or clearly delimited, noninvasive neoplasm with a follicular growth pattern and nuclear features of papillary thyroid carcinoma (PTC). It is considered a ‘pre-malignant’ lesion of the RAS-like group. Ultrasonography (US), cytology and molecular tests are useful to suspect thyroid nodules that correspond to NIFTP but there is wide overlap of the results with the encapsulated follicular variant of PTC (E-FVPTC). In these nodules that possibly or likely correspond to NIFTP, if surgery is indicated, lobectomy is favored over total thyroidectomy. The diagnosis of NIFTP is made after complete resection of the lesion by observing well-defined criteria. In the case of patients who received the diagnosis of FVPTC and whose pathology report does not show findings of malignancy (lymph node metastasis, extrathyroidal invasion, vascular/capsular invasion), if the tumor was encapsulated or well delimited, the slides can be revised by an experienced pathologist to determine whether the diagnostic criteria of NIFTP are met, but special attention must be paid to the adequate representativeness of the capsule and tumor. Since NIFTP is not ‘malignant’, tumor staging is not necessary and patients are not submitted to thyroid cancer protocols or guidelines. We believe that patients with NIFTP without associated malignancy and without nodules detected by US of the remnant lobe (if submitted to lobectomy) can be managed like those with follicular adenoma.
Rehannah Borup, Maria Rossing, Ricardo Henao, Yohei Yamamoto, Annelise Krogdahl, Christian Godballe, Ole Winther, Katalin Kiss, Lise Christensen, Estrid Høgdall, Finn Bennedbæk, and Finn Cilius Nielsen
The molecular pathways leading to thyroid follicular neoplasia are incompletely understood, and the diagnosis of follicular tumors is a clinical challenge. To provide leads to the pathogenesis and diagnosis of the tumors, we examined the global transcriptome signatures of follicular thyroid carcinoma (FC) and normofollicular adenoma (FA) as well as fetal/microFA (fetal adenoma). Carcinomas were strongly enriched in transcripts encoding proteins involved in DNA replication and mitosis corresponding to increased number of proliferating cells and depleted number of transcripts encoding factors involved in growth arrest and apoptosis. In the latter group, the combined loss of transcripts encoding the nuclear orphan receptors NR4A1 and NR4A3, which were recently shown to play a causal role in hematopoetic neoplasia, was noteworthy. The analysis of differentially expressed transcripts provided a mechanism for cancer progression, which is why we exploited the results in order to generate a molecular classifier that could identify 95% of all carcinomas. Validation employing public domain and cross-platform data demonstrated that the signature was robust and could diagnose follicular nodules originating from different geographical locations and platforms with similar accuracy. We came to the conclusion that down-regulation of factors involved in growth arrest and apoptosis may represent a decisive step in the pathogenesis of FC. Moreover, the described molecular pathways provide an accurate and robust genetic signature for the diagnosis of FA and FC.
Willem E Corver, Joris Demmers, Jan Oosting, Shima Sahraeian, Arnoud Boot, Dina Ruano, Tom van Wezel, and Hans Morreau
A near-homozygous genome (NHG) is especially seen in a subset of follicular thyroid cancer of the oncocytic type (FTC-OV). An NHG was also observed in the metabolically relatively quiescent cell lines XTC.UC1, a model for FTC-OV, and in FTC-133, -236 and -238, the latter three derived from one single patient with follicular thyroid cancer. FTC-236 subclones showed subtle whole-chromosome differences indicative of sustained reciprocal mitotic missegregations. Reactive oxygen species (ROS) scavenger experiments reduced the number of chromosomal missegregations in XTC.UC1 and FTC-236, while pCHK2 was downregulated in these cells. Treatment with antimycin A increased ROS indicated by enhanced MitoSOX Red and pCHK2 fluorescence in metaphase cells. In a selected set of oncocytic follicular thyroid tumors, increasing numbers of whole-chromosome losses were observed toward an aggressive phenotype, but with retention of chromosome 7. Together, ROS activates CHK2 and links to the stepwise loss of whole chromosomes during tumor progression in these lesions. We postulate that sequential loss of whole chromosomes is a dominant driver of the oncogenesis of a subset of follicular thyroid tumors.
J Di Cristofaro, M Silvy, A Lanteaume, M Marcy, P Carayon, and C De Micco
Immunocytochemistry (ICC) of thyroid peroxidase (TPO) using the monoclonal antibody MoAb47 has been used as malignancy marker on thyroid fine needle aspiration. However, little is known about the fate of TPO in thyroid carcinoma. We performed a qualitative PCR (Q-PCR) analysis to measure the expression of variants of tpo mRNA in 13 normal tissue samples, 30 benign tumors (BT), 21 follicular carcinomas (FC), 20 classical papillary carcinomas (PCc), 12 follicular variants of papillary carcinomas (PCfv) and nine oncocytic carcinomas (OC). We also studied mutations involving the ras, Braf, ret or pax8 genes. Results of Q-PCR were closely correlated with those of ICC (P < 0.0001; R = 0.59) and showed that overall tpo expression was lower in all carcinomas than in normal and BT (P < 0.05). The ratio tpo2 or tpo3 to tpo1 was inversed in follicular tumors. Genetic mutations were observed in 90% of PCc, 61.9% of FC, 41.7% of PCfv, 0% of OC and 10% in BT. pax8-ppar γ1 rearrangement was correlated with qualitative changes in tpo mRNA (P < 0.01). These results confirmed the decrease of TPO expression in 97% of thyroid carcinomas regardless of histological type and the overexpression of shorter splice variants in follicular tumors. Both reduction in quantity of TPO and impairment of its maturation process could account for the atypical immunohistochemical reaction of MoAb47 with TPO.
Theodoros Foukakis, Arief Gusnanto, Amy YM Au, Anders Höög, Weng-Onn Lui, Catharina Larsson, Göran Wallin, and Jan Zedenius
The diagnosis of follicular thyroid carcinoma (FTC) in the absence of metastasis can only be established postoperatively. Moreover, high-risk FTCs are often not identifiable at the time of diagnosis. In this study, we aimed to identify transcriptional markers of malignancy and high-risk disease in follicular thyroid tumors. The expression levels of 26 potential markers of malignancy were determined in a panel of 75 follicular thyroid tumors by a TaqMan quantitative RT-PCR approach. Logistic regression analysis (LRA) was used for gene selection and generation of diagnostic and prognostic algorithms. An algorithm based on the expression levels of five genes (TERT, TFF3, PPARγ, CITED1, and EGR2) could effectively predict high-risk disease with a specificity of 98.5%. The metastatic potential could be predicted in all four cases with apparently benign or minimally invasive (MI) disease at the time of diagnosis, but poor long-term outcome. In addition, a second model was produced by implementing two genes (TERT and TFF3), which was able to distinguish adenomas from de facto carcinomas. When this model was tested in an independent series of atypical adenomas (AFTA) and MI-FTCs, 16 out of 17 AFTAs were classified as ‘benign’, while MI-FTCs with vascular invasion (sometimes referred to as ‘moderately invasive’) and/or large tumor size tended to classify in the ‘malignant’ group. The reported models can be the foundation for the development of reliable preoperative diagnostic and prognostic tests that can guide the therapeutic approach of follicular thyroid neoplasms with indeterminate cytology.
G R Mundy and T A Guise
Tumors cause multiple effects on the skeleton and on calcium homeostasis, but they do so in specific patterns which are becoming better defined as the mediators responsible become more fully characterized. Metastatic bone disease occurs in the majority of patients with advanced cancer, and is particularly frequent in breast, lung and prostate cancers, which are the most common of all human tumors. Approximately 1,000 000 people die each year in Western Europe and the United States from these three malignancies, and the majority of these people have bone metastases. Bone is the third most common site of metastatic disease in tumors of all types and the second most common in breast and prostate cancer. In this review, the role of the tumor peptide parathyroid hormone-related peptide (PTH-rP) in the effects of cancer on the skeleton will be discussed.