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Sunmi Park, Mark C Willingham, Jun Qi, and Sheue-Yann Cheng

Compelling epidemiological evidence shows a strong positive correlation of obesity with thyroid cancer. In vivo studies have provided molecular evidence that high-fat-diet-induced obesity promotes thyroid cancer progression by aberrantly activating leptin-JAK2-STAT3 signaling in a mouse model of thyroid cancer (Thrb PV/PV Pten +/ mice). The Thrb PV/PV Pten +/ mouse expresses a dominantly negative thyroid hormone receptor β (denoted as PV) and a deletion of one single allele of the Pten gene. The Thrb PV/PV Pten +/ mouse spontaneously develops follicular thyroid cancer, which allows its use as a preclinical mouse model to test potential therapeutics. We recently showed that inhibition of STAT3 activity by a specific inhibitor markedly delays thyroid cancer progression in high-fat-diet-induced obese Thrb PV/PV Pten +/ mice (HFD-Thrb PV/PV Pten +/ mice). Further, metformin, a widely used antidiabetic drug, blocks invasion and metastasis, but not thyroid tumor growth in HFD-Thrb PV/PV Pten +/ mice. To improve efficacy in reducing thyroid tumor growth, we treated HFD-Thrb PV/PV Pten +/ with JQ1, a potent inhibitor of the activity of bromodomain and extraterminal domain (BET) and with metformin. We found that the combined treatment synergistically suppressed thyroid tumor growth by attenuating STAT3 and ERK signaling, resulting in decreased anti-apoptotic key regulators such as Mcl-1, Bcl-2 and survivin and increased pro-apoptotic regulators such as Bim, BAD and cleave caspase 3. Furthermore, combined treatment of JQ1 and metformin reduced cMyc protein levels to suppress vascular invasion, anaplasia and lung metastasis. These findings indicate that combined treatment is more effective than metformin alone and suggest a novel treatment modality for obesity-activated thyroid cancer.

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D Deandreis, A Al Ghuzlan, S Leboulleux, L Lacroix, J P Garsi, M Talbot, J Lumbroso, E Baudin, B Caillou, J M Bidart, and M Schlumberger

The aim of this study is to search for relationships between histology, radioiodine (131I) uptake, fluorodeoxyglucose (FDG) uptake, and disease outcome in patients with metastatic thyroid cancer. Eighty patients with metastatic thyroid cancer (34 males, 46 females, mean age at the time of the diagnosis of metastases: 55 years) were retrospectively studied. All patients were treated with radioactive iodine and evaluated by FDG-positron emission tomography (PET). Primary tumor tissue sample was available in all cases. Forty-five patients (56%) had a papillary, 12 (15%) a follicular, and 23 (29%) a poorly differentiated thyroid cancer. Cellular atypias, necrosis, mitoses, thyroid capsule infiltration, and vascular invasion were frequently detected (70, 44, 52, 60, and 71% respectively). Metastases disclosed FDG uptake in 58 patients (72%) and 131I uptake in 37 patients (45%). FDG uptake was the only significant prognostic factor for survival (P=0.02). The maximum standardized uptake value and the number of FDG avid lesions were also related to prognosis (P=0.03 and 0.009). Age at the time of the diagnosis of metastases (P=0.001) and the presence of necrosis (P=0.002) were independent predictive factors of FDG uptake. Radioiodine uptake was prognostic for stable disease (P=0.001) and necrosis for progressive disease at 1 year (P=0.001). Histological subtype was not correlated with in vivo tumor metabolism and prognosis. In conclusion, FDG uptake in metastatic thyroid cancer is highly prognostic for survival. Histological subtype alone does not correlate with 131I/FDG uptake pattern and patient outcome. Well-differentiated thyroid cancer presenting histological features such as necrosis and FDG uptake on PET scan should be considered aggressive differentiated cancers.

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Eleonore Fröhlich, Fausto Machicao, and Richard Wahl

Differentiating drugs may be able to re-sensitize thyroid carcinomas to radioiodine therapy. Substituted thiazolidinediones (TZDs) belong to the group of oral anti-diabetic drugs that also possess anti-proliferative and pro-apoptotic effects and, potentially, differentiating effects on several cancer cell lines. Some of the effects are mediated via the peroxisome proliferator-activated receptor gamma (PPAR-γ). We investigated the effect of troglitazone, rosiglitazone and pioglitazone on differentiation in normal porcine thyrocytes and in the follicular carcinoma cell lines FTC 133 and FTC 238. Differentiation was investigated by measuring 125I uptake and the expression of sodium-iodide symporter and thyroglobulin proteins. The TZDs were tested in the presence of retinol and retinoic acid. Additionally, proliferation was evaluated by [3H]thymidine uptake and cell number and apoptosis by annexin V-labeling. Controls included tocopherol and unsubstituted thiazolidinedione and co-incubation of the TZDs with the PPAR-γ antagonist GW9662. PPAR-γ and retinol X receptor (RXR)-α were investigated by immunocytochemistry, Western blot and RT-PCR. Cells derived from the metastasis showed greater responses than cells derived from the primary tumor. Troglitazone showed greater effects than the other TZDs. Troglitazone significantly increased 125I uptake and apoptosis and decreased [3H]thymidine uptake and cell number. The amount of the sodium iodide-symporter in the membrane fraction was significantly increased, while that of thyroglobulin was not influenced by the treatment. Inclusion of antagonist did not abolish these effects. No synergistic effect with any retinoid was detected. All transformed cells expressed PPAR-γ and RXR-α but TZDs did not change their expression.

Troglitazone appears to be suited for the re-differentiation treatment of dedifferentiated thyroid carcinoma because its action is twofold. On the one hand it increases differentiation and on the other hand it inhibits proliferation.

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Thomas A Werner, Inga Nolten, Levent Dizdar, Jasmin C Riemer, Sina C Schütte, Pablo E Verde, Katharina Raba, Matthias Schott, Wolfram T Knoefel, and Andreas Krieg

Follicular thyroid cancer’s (FTC) excellent long-term prognosis is mainly dependent on postoperative radioactive iodine (RAI) treatment. However, once the tumour becomes refractory, the 10-year disease-specific survival rate drops below 10%. The aim of our study was to evaluate the prognostic and biological role of the TRAIL system in FTC and to elucidate the influence of small-molecule-mediated antagonisation of inhibitor of apoptosis proteins (IAPs) on TRAIL sensitivity in vitro. Tissue microarrays were constructed from forty-four patients with histologically confirmed FTC. Expression levels of TRAIL and its receptors were correlated with clinicopathological data and overall as well as recurrence-free survival. Non-iodine-retaining FTC cell lines TT2609-bib2 and FTC133 were treated with recombinant human TRAIL alone and in combination with Smac mimetics GDC-0152 or Birinapant. TRAIL-R2/DR5 as well as TRAIL-R3/DcR1 and TRAIL-R4/DcR2 were significantly higher expressed in advanced tumour stages. Both decoy receptors were negatively associated with recurrence-free and overall survival. TRAIL-R4/DcR2 additionally proved to be an independent negative prognostic marker in FTC (HR = 1.446, 95% CI: 1.144–1.826; P < 0.001). In vitro, the co-incubation of Birinapant or GDC-0152 with rh-TRAIL-sensitised FTC cell lines for TRAIL-induced apoptosis, through degradation of cIAP1/2. The TRAIL system plays an important role in FTC tumour biology. Its decoy receptors are associated with poor prognosis as well as earlier recurrence. The specific degradation of cIAP1/2 sensitises FTC cells to TRAIL-induced apoptosis and might highlight a new point of attack in patients with RAI refractory disease.

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Margarida M Moura, Branca M Cavaco, and Valeriano Leite

Medullary thyroid carcinoma (MTC) is a rare malignancy originating from the calcitonin-secreting parafollicular thyroid C cells. Approximately 75% of cases are sporadic. Rearranged during transfection (RET) proto-oncogene plays a crucial role in MTC development. Besides RET, other oncogenes commonly involved in the pathogenesis of human cancers have also been investigated in MTC. The family of human RAS genes includes the highly homologous HRAS, KRAS, and NRAS genes that encode three distinct proteins. Activating mutations in specific hotspots of the RAS genes are found in about 30% of all human cancers. In thyroid neoplasias, RAS gene point mutations, mainly in NRAS, are detected in benign and malignant tumors arising from the follicular epithelium. However, recent reports have also described RAS mutations in MTC, namely in HRAS and KRAS. Overall, the prevalence of RAS mutations in sporadic MTC varies between 0–43.3%, occurring usually in tumors with WT RET and rarely in those harboring a RET mutation, suggesting that activation of these proto-oncogenes represents alternative genetic events in sporadic MTC tumorigenesis. Thus, the assessment of RAS mutation status can be useful to define therapeutic strategies in RET WT MTC. MTC patients with RAS mutations have an intermediate risk for aggressive cancer, between those with RET mutations in exons 15 and 16, which are associated with the worst prognosis, and cases with other RET mutations, which have the most indolent course of the disease. Recent results from exome sequencing indicate that, besides mutations in RET, HRAS, and KRAS, no other recurrent driver mutations are present in MTC.

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Thomas Gudermann and Susanne Roelle

Approximately 15–25% of all primary cancers of the lung are classified histologically as small cell lung carcinoma (SCLC), a subtype characterized by rapid growth and a poor prognosis. Neuropeptide hormones like bombesin/gastrin-releasing peptide, bradykinin or galanin are the principal mitogenic stimuli of this tumour entity. The mitogenic signal is transmitted into the cell via heptahelical neuropeptide hormone receptors, which couple to the heterotrimeric G proteins of the Gq/11 familiy. Subsequent activation of phospholipase Cβ (PLCβ) entails the activation of protein kinase C and the elevation of the intracellular calcium concentration. There is mounting evidence to support the notion that calcium mobilization is the key event that initiates different mitogen-activated protein kinase cascades. Neuropeptide-dependent proliferation of SCLC cells relies on parallel activation of the Gq/11/PLCβ/Ras/extracellular signal-regulated kinase and the c-jun N-terminal kinase pathways, while selective engagement of either signalling cascade alone results in growth arrest and differentiation or apoptotic cell death. Basic experimental research has the potential to identify and validate novel therapeutic targets located at critical points of convergence of different mitogenic signal transduction pathways. In the case of SCLC, targeting the distinct components of the Ca2+ influx pathway as well as critical Ca2+-dependent cellular effectors may be rewarding in this regard.

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E L Mazzaferri and N Massoll

The incidence of differentiated thyroid cancer (DTC) has increased in many places around the world over the past three decades, yet this has been associated with a significant decrease in DTC mortality rates in some countries. While the best 10-year DTC survival rates are about 90%, long-term relapse rates remain high, in the order of 20-40%, depending upon the patient's age and tumor stage at the time of initial treatment. About 80% of patients appear to be rendered disease-free by initial treatment, but the others have persistent tumor, sometimes found decades later. Optimal treatment for tumors that are likely to relapse or cause death is total thyroidectomy and ablation by iodine-131 ((131)I), followed by long-term levothyroxine suppression of thyrotropin (TSH). On the basis of regression modeling of 1510 patients without distant metastases at the time of initial treatment and including surgical and (131)I treatment, the likelihood of death from DTC is increased by several factors, including age >45 years, tumor size >1.0 cm, local tumor invasion or regional lymph-node metastases, follicular histology, and delay of treatment >12 months. Cancer mortality is favorably and independently affected by female sex, total or near-total thyroidectomy, (131)I treatment and levothyroxine suppression of TSH. Treatments with (131)I to ablate thyroid remnants and residual disease are independent prognostic variables favorably influencing distant tumor relapse and cancer death rates. Delay in treatment of persistent disease has a profound impact on outcome. Optimal long-term follow-up using serum thyroglobulin (Tg) measurements and diagnostic whole-body scans (DxWBS) require high concentrations of TSH, which until recently were possible to achieve only by withdrawing levothyroxine treatment, producing symptomatic hypothyroidism. New paradigms, however, provide alternative pathways to prepare patients for (131)I treatment and to optimize follow-up. Patients with undetectable or low Tg concentrations and persistent occult disease can now be identified within the first year after initial treatment by recombinant human (rh)TSH-stimulated serum Tg concentrations greater than 2 microg/l, without performing DxWBS. These new follow-up paradigms promptly identify patients with lung metastases that are not evident on routine imaging, but which respond to (131)I treatment. In addition, rhTSH can be given to prepare patients for (131)I remnant ablation or (131)I treatment for metastases, especially those who are unable to withstand hypothyroidism because of concurrent illness or advanced age, or whose hypothyroid TSH fails to increase.

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L Fugazzola, E Puxeddu, N Avenia, C Romei, V Cirello, A Cavaliere, P Faviana, D Mannavola, S Moretti, S Rossi, M Sculli, V Bottici, P Beck-Peccoz, F Pacini, A Pinchera, F Santeusanio, and R Elisei

Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype–phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of χ2/Fisher’s exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF V600E mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF V600E was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF V600E and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF V600E (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38–40%. Furthermore, B-RAF V600E was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.

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Sandra Rodríguez-Rodero, Elías Delgado-Álvarez, Agustín F Fernández, Juan L Fernández-Morera, Edelmiro Menéndez-Torre, and Mario F Fraga

Aberrant epigenetics is a hallmark of cancer, and endocrine-related tumors are no exception. Recent research has been identifying an ever-growing number of epigenetic alterations in both genomic DNA methylation and histone post-translational modification in tumors of the endocrine system. Novel microarray and ultra-deep sequencing technologies have allowed the identification of genome-wide epigenetic patterns in some tumor types such as adrenocortical, parathyroid, and breast carcinomas. However, in other cancer types, such as the multiple endocrine neoplasia syndromes and thyroid cancer, tumor information is limited to candidate genes alone. Future research should fill this gap and deepen our understanding of the functional role of these alterations in cancer, as well as defining their possible clinical uses.

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F Cetani, E Pardi, E Ambrogini, P Viacava, S Borsari, M Lemmi, L Cianferotti, P Miccoli, A Pinchera, A Arnold, and C Marcocci

Early onset of primary hyperparathyroidism (PHPT) and multiglandular involvement suggest a familial form in which germline mutation of a PHPT-related gene(s) and a somatic event at the same locus can be often demonstrated. We investigated the involvement of multiple endocrine neoplasia type 1 (MEN1) and HRPT2 genes in a 39-year-old man with recurrent PHPT. PHPT was firstly diagnosed at the age of 21 and the patient had two recurrences separated by extended periods of normocalcemia. This unusual history prompted us to investigate other family members and study the MEN1 and HRPT2 genes. An HRPT2 germline missense mutation in exon 3 (R91P) was found in the index case, which was associated with different HRPT2 somatic alterations in each of the three examined parathyroid tumors. These findings are consistent with Knudson’s ‘two hit’ concept of biallelic inactivation of classical tumor suppressor genes. Screening of 15 asymptomatic relatives was negative for the R91P germline mutation. All the three abnormal parathyroid specimens showed cystic features at histology and were negative for parafibromin immunostaining. In one specimen, diffuse parafibromin staining was evident in a rim of normal parathyroid tissue surrounding the adenomatous lesion. Our study shows that different somatic genetic events at the HRPT2 locus are responsible for the asynchronous occurrence of multiple adenomas in a patient carrying an HRPT2 germline mutation. The finding of diffuse parafibromin staining in a rim of normal parathyroid tissue, but not in the contiguous adenomatous lesion, reinforces the concept that loss of parafibromin expression is responsible for the development of parathyroid tumors in this setting.