Our main objective was to search for mutations in candidate genes and for paired box gene 8–peroxisome proliferator-activated receptor gamma (PAX8–PPARγ) rearrangement in a well-differentiated angioinvasive follicular thyroid carcinoma (FTC) causing hyperthyroidism. DNA and RNA were extracted from the patient's thyroid tumor, as well as ‘normal’ thyroid tissue, and from peripheral blood lymphocytes (PBLs) of the patient, her daughter, and two siblings. Nuclear isolation was extracted from the patient's tumor, ’normal’ thyroid tissue, PBLs, and uterine leiomyoma tissue. TSH receptor (TSHR), RAS, and BRAF genes were sequenced. We searched for PAX8 – PPAR γ in thyroid, PBL, and uterine leiomyoma samples from the patient and family members. Proliferative effects of detected mutants on non-transformed human thyrocytes cultures. An activating TSHR mutation, M453T, was detected in the tumor. PAX8 (exons 1 – 8 + 10)– PPAR γ was found in all tested patient's tissues. A second rearrangement, PAX8 (exons 1 – 8)– PPAR γ, was detected in the patient's normal thyroid tissue. Under deprived medium condition, co-transfection of PAX8 – PPAR γ and TSHR – M453T dramatically increased the number of thyrocytes, an effect that it was not observed with TSHR wild-type (WT); under complete medium conditions, co-transfection of PAX8 – PPAR γ with either TSHR – M453T or TSHR – WT inhibited cell proliferation. We report a patient with hyperthyroidism due to a FTC bearing an activating TSHR mutation and PAX8 – PPAR γ rearrangements. PAX8 – PPAR γ was present as a mosaicism affecting tissues from endodermal and mesodermal origin. PAX8 – PPAR γ and TSHR – M453T inhibited or promoted thyrocyte proliferation depending on medium conditions. The activating TSHR mutation could promote in vivo FTC development in PAX8 – PPAR γ-positive thyrocytes under poor blood supply with deprivation of growth factors but restraint the tumor growth when growth factors are supplied.
J Lado-Abeal, R Celestino, S B Bravo, M E R Garcia-Rendueles, J de la Calzada, I Castro, P Castro, C Espadinha, F Palos, P Soares, C V Alvarez, M Sobrinho-Simões, and J Cameselle-Teijeiro
Hai-Yan Zhang, Hua-Qin Wang, Hai-Mei Liu, Yifu Guan, and Zhen-Xian Du
DJ-1, a cancer-associated protein protects cells from multiple toxic stresses. The expression of DJ-1 and its influence on thyroid cancer cell death has not been investigated so far. We analyzed DJ-1 expression in human thyroid carcinoma cell lines and the effect of DJ-1 on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. DJ-1 was expressed in human thyroid carcinoma cell lines; small interfering RNA-mediated downregulation of its levels significantly sensitized thyroid carcinoma cells to TRAIL-induced apoptosis, whereas the forced exogenous expression of DJ-1 significantly suppressed cell death induced by TRAIL. We also report here that TRAIL-induced thyroid cancer cell apoptosis is mediated by oxidative stress and that DJ-1, a potent nutritional antioxidant, protects cancer cells from apoptosis at least in part by impeding the elevation of reactive oxygen species levels induced by TRAIL and impairing caspase-8 activation. Subsequently, we investigated DJ-1 expression in 52 normal and 74 primary thyroid carcinomas from patients of China Medical University. The protein was not detectable in the 52 specimens of normal thyroid, while 70 out of 74 analyzed carcinomas (33 out of 33 follicular, 17 out of 19 papillary, 12 out of 13 medullar, and 8 out of 9 anaplastic) were clearly positive for DJ-1 expression. Our data demonstrated that DJ-1 is specifically expressed in thyroid carcinomas and not in the normal thyroid tissue. In addition, the protein modulates the response to TRAIL-mediated apoptosis in human neoplastic thyroid cells, at least partially through its antioxidant property.
Carla Colombo, Marina Muzza, Gabriele Pogliaghi, Sonia Palazzo, Guia Vannucchi, Leonardo Vicentini, Luca Persani, Giacomo Gazzano, and Laura Fugazzola
Cytology is the gold standard method for the differential diagnosis of thyroid nodules, though 25–30% of them are classified as indeterminate. We aimed to set up a ‘thyroid risk score’ (TRS) to increase the diagnostic accuracy in these cases. We prospectively tested 135 indeterminate thyroid nodules. The pre-surgical TRS derived from the sum of the scores assigned at cytology, EU-TIRADS classification, nodule measurement, and molecular characterization, which was done by our PTC-MA assay, a customized array able to cost-effectively evaluate 24 different genetic alterations including point mutations and gene fusions. The risk of malignancy (ROM) increased paralleling the score: in the category >4 and ≤ 6 (low suspicion), >6 ≤ 8 (intermediate suspicion), and >8 (high suspicion); ROM was 10, 47 and 100%, respectively. ROC curves selected the score >6.5 as the best threshold to differentiate between malignant and benign nodules (P < 0.001). The TRS > 6.5 had a better performance than the single parameters evaluated separately, with an accuracy of 77 and 82% upon inclusion of noninvasive follicular thyroid neoplasm with papillary-like nuclear features among malignant or benign cases, respectively. In conclusion, for the first time, we generated a score combining a cost-effective molecular assay with already validated tools, harboring different specificities and sensitivities, for the differential diagnosis of indeterminate nodules. The combination of different parameters reduced the number of false negatives inherent to each classification system. The TRS > 6.5 was highly suggestive for malignancy and retained a high accuracy in the identification of patients to be submitted to surgery.
Xuguang Zhu, Dong Wook Kim, Li Zhao, Mark C Willingham, and Sheue-yann Cheng
Thyroid cancer is on the rise. Novel approaches are needed to improve the outcome of patients with recurrent and advanced metastatic thyroid cancers. FDA approval of suberoylanilide hydroxamic acid (SAHA; vorinostat), an inhibitor of histone deacetylase, for the treatment of hematological malignancies led to the clinical trials of vorinostat for advanced thyroid cancer. However, patients were resistant to vorinostat treatment. To understand the molecular basis of resistance, we tested the efficacy of SAHA in two mouse models of metastatic follicular thyroid cancer: ThrbPV/PV and ThrbPV/PVPten+/− mice. In both, thyroid cancer is driven by overactivation of PI3K-AKT signaling. However, the latter exhibit more aggressive cancer progression due to haplodeficiency of the tumor suppressor, the Pten gene. SAHA had no effects on thyroid cancer progression in ThrbPV/PV mice, indicative of resistance to SAHA. Unexpectedly, thyroid cancer progressed in SAHA-treated ThrbPV/PVPten+/− mice with accelerated occurrence of vascular invasion, anaplastic foci, and lung metastasis. Molecular analyses showed further activated PI3K-AKT in thyroid tumors of SAHA-treated ThrbPV/PVPten+/− mice, resulting in the activated effectors, p-Rb, CDK6, p21Cip1, p-cSrc, ezrin, and matrix metalloproteinases, to increase proliferation and invasion of tumor cells. Single-molecule DNA analysis indicated that the wild-type allele of the Pten gene was progressively lost, whereas carcinogenesis progressed in SAHA-treated ThrbPV/PVPten+/− mice. Thus, this study has uncovered a novel mechanism by which SAHA-induced loss of the tumor suppressor Pten gene to promote thyroid cancer progression. Effectors downstream of the Pten loss-induced signaling may be potential targets to overcome resistance of thyroid cancer to SAHA.
Zhaoxia Zhang, Sasha Beyer, and Sissy M Jhiang
The Na+/I− symporter (NIS (SLC5A5)) is a transmembrane glycoprotein that mediates active iodide uptake into thyroid follicular cells. NIS-mediated iodide uptake in thyroid cells is the basis for targeted radionuclide imaging and treatment of differentiated thyroid carcinomas and their metastases. Furthermore, NIS is expressed in many human breast tumors but not in normal non-lactating breast tissue, suggesting that NIS-mediated radionuclide uptake may also allow the imaging and targeted therapy of breast cancer. However, functional cell surface NIS expression is often low in breast cancer, making it important to uncover signaling pathways that modulate NIS expression at multiple levels, from gene transcription to posttranslational processing and cell surface trafficking. In this study, we investigated NIS regulation in breast cancer by MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK) signaling, an important cell signaling pathway involved in oncogenic transformation. We found that MEK inhibition decreased NIS protein levels in all-trans retinoic acid/hydrocortisone-treated MCF-7 cells as well as human breast cancer cells expressing exogenous NIS. The decrease in NIS protein levels by MEK inhibition was not accompanied by a decrease in NIS mRNA or a decrease in NIS mRNA export from the nucleus to the cytoplasm. NIS protein degradation upon MEK inhibition was prevented by lysosome inhibitors but not by proteasome inhibitors. Interestingly, NIS protein level was correlated with MEK/ERK activation in human breast tumors from a tissue microarray. Taken together, MEK activation appears to play an important role in maintaining NIS protein stability in human breast cancers.
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.
Kirk Jensen, Athanasios Bikas, Aneeta Patel, Yevgeniya Kushchayeva, John Costello, Dennis McDaniel, Kenneth Burman, and Vasyl Vasko
The HIV protease inhibitor Nelfinavir (NFV) inhibits PI3K/AKT and MAPK/ERK signaling pathways, emerging targets in thyroid cancers. We examined the effects of NFV on cancer cells that derived from follicular (FTC), papillary (PTC) and anaplastic (ATC) thyroid cancers. NFV (1–20 µM) was tested in FTC133, BCPAP and SW1736 cell lines. The effects of NFV on cell proliferation were determined in vitro using real-time microscopy and by flow cytometry. DNA damage, apoptotic cell death and expression of molecular markers of epithelial–mesenchymal transition (EMT) were determined by Western blot and real-time PCR. Real-time imaging demonstrated that NFV (10 µM) increased the time required for the cell passage through the phases of cell cycle and induced DNA fragmentation. Growth inhibitory effects of NFV were associated with the accumulation of cells in G0/G1 phase, downregulation of cyclin D1 and cyclin-dependent kinase 4 (CDK4). NFV also induced the expression of γH2AX and p53BP1 indicating DNA damage. Treatment with NFV (20 µM) resulted in caspase-3 cleavage in all examined cells. NFV (20 µM) decreased the levels of total and p-AKT in PTEN-deficient FTC133 cells. NFV had no significant effects on total ERK and p-ERK in BRAF-positive BCPAP and SW1736 cells. NFV had no effects on the expression of EMT markers (Twist, Vimentin, E- and N-Cadherin), but inhibited the migration and decreased the abilities of thyroid cancer cells to survive in non-adherent conditions. We conclude that NFV inhibits proliferation and induces DNA damage in thyroid cancer cell lines. Our in vitro data suggest that NFV has a potential to become a new thyroid cancer therapeutic agent.
Xiulong Xu, Helen Ding, Geetha Rao, Shalini Arora, Constantine P Saclarides, Joseph Esparaz, Paolo Gattuso, Carmen C Solorzano, and Richard A Prinz
The sonic hedgehog (SHH) pathway is activated in several types of malignancy and plays an important role in tumor cell proliferation and tumorigenesis. SHH binding to a 12-pass transmembrane receptor, Patched (PTCH), leads to freeing of Smoothened (SMO) and subsequent activation of GLI transcription factors. In the present study, we analyzed the expression of SHH, PTCH, SMO, and GLI1 in 31 follicular thyroid adenomas (FTA), 8 anaplastic thyroid carcinomas (ATC), and 51 papillary thyroid carcinomas (PTC) by immunohistochemical staining. More than 65% of FTA, PTC, and ATC specimens stained positive for SHH, PTCH, SMO, and GLI. However, the expression of the genes encoding these four molecules did not correlate with any clinicopathologic parameters, including the age, gender, the status of BRAF gene mutation, tumor stage, local invasion, and metastasis. Three thyroid tumor cell lines (KAT-18, WRO82, and SW1736) all expressed the genes encoding these four molecules. 5-Bromo-2-deoxyuridine labeling and MTT cell proliferation assays revealed that cyclopamine (CP), an inhibitor of the SHH pathway, was able to inhibit the proliferation of KAT-18 and WRO82 cells more effectively than SW1736 cells. CP led to the arrest of cell cycle or apoptosis. Knockdown of SHH and GLI expression by miRNA constructs that target SHH or GLI mRNA in KAT-18 and SW1736 cells led to the inhibition of cell proliferation. Our results suggest that the SHH pathway is widely activated in thyroid neoplasms and may have potential as an early marker of thyroid cancer or as a potential therapeutic target for thyroid cancer treatment.
Garcilaso Riesco-Eizaguirre and Pilar Santisteban
Well-differentiated thyroid cancer has in general terms a very good outcome. It has a very slow growth rate and, although it metastasises at a relatively high frequency, it has very high survival rates. Whereas the prevalence of nodular thyroid disease worldwide is high, malignant conversion from benign thyroid nodules is rare. Treatment of thyroid cancer is usually successful, but we still do not have effective therapies for patients with invasive or metastatic thyroid cancer if the disease does not concentrate radioiodine and it is not surgically resectable. On the other hand, from the same thyroid cell, one of the most aggressive human tumours can arise – undifferentiated or anaplastic thyroid carcinoma – leading to death in a few months. What features of this malignancy account for such paradoxical behaviour? The most common type of thyroid cancer – papillary thyroid carcinoma – stands out among solid tumours because many of the tumour-initiating events have been identified. All of them function in a single pathway – the RTK/RAS/RAF/MAPK pathway – and obey an ‘exclusivity principle’: one and only one component of the pathway is mutated in a single tumour. This highlights the requirement of this signal transduction pathway for the transformation to thyroid cancer and paves the way to targeted therapies against a tumour with a mutation in a known gene or any gene upstream of the target. However, it is also interesting to underscore the differences among the tumours arising from the different mutations. Studies in vitro and in vivo, including genomic profiling and genetically engineered mouse models, have clearly shown that each oncoprotein exerts its own oncogenic drive, conferring a distinct biological behaviour on thyroid tumours. In this review, we attempt to summarise the most recent advances in thyroid follicular cell-derived cancers research and their potential clinical impact that may change the management of thyroid cancer in the near future.
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.