Medical management of metastatic medullary thyroid cancer

Expression and prognosis analysis of integrin subunit α3 (ITGA3) in papillary thyroid cancer

Integrin subunit α3 (ITGA3) is a member of the integrin family and interacts with extracellular matrix proteins. However, there have been few reports regarding the role of ITGA3 in papillary thyroid cancer. The expression levels of ITGA3 were firstly analyzed by bioinformatics tools and in vitro experiments, followed by evaluating its prognostic significance in papillary thyroid cancer patients using Kaplan-Meier, receiver operating characteristic, and Cox regression analyses. Then, cBioportal and GSCA databases were applied to evaluate genetic alterations of ITGA3. Functional enrichment analysis was conducted and the upstream miRNAs of ITGA3 were determined. The results showed that the ITGA3 mRNA and protein levels were higher in the papillary thyroid cancer group than those in the normal group (all P < 0.05). Moreover, ITGA3 performed well in distinguishing the recurrence-free survival (RFS) status and served as an independent prognostic factor of papillary thyroid cancer patients (P < 0.01). Besides, significant relations between ITGA3 and genetic alterations were observed (FDR <0.01). Functional enrichment analysis indicated ECM-receptor interaction and cell adhesion molecules were the shared regulatory pathways. Moreover, ITGA3 might be the target gene of hsa-miR-3129, hsa-miR-181d, hsa-miR-181b, hsa-miR-199a, and hsa-miR-199b. Of note, the ITGA3 mRNA level was reduced after has-miR-199b-3p/5p was overexpressed. In conclusion, ITGA3 could be a reliable biomarker and have potential value in predicting the RFS status of papillary thyroid cancer patients.

Faulty Metabolism: A Potential Instigator of an Aggressive Phenotype in Cdk5-dependent Medullary Thyroid Carcinoma

Mechanistic modeling of cancers such as Medullary Thyroid Carcinoma (MTC) to emulate patient-specific phenotypes is challenging. The discovery of potential diagnostic markers and druggable targets in MTC urgently requires clinically relevant animal models. Here we established orthotopic mouse models of MTC driven by aberrantly active Cdk5 using cell-specific promoters. Each of the two models elicits distinct growth differences that recapitulate the less or more aggressive forms of human tumors. The comparative mutational and transcriptomic landscape of tumors revealed significant alterations in mitotic cell cycle processes coupled with the slow-growing tumor phenotype. Conversely, perturbation in metabolic pathways emerged as critical for aggressive tumor growth. Moreover, an overlapping mutational profile was identified between mouse and human tumors. Gene prioritization revealed putative downstream effectors of Cdk5 which may contribute to the slow and aggressive growth in the mouse MTC models. In addition, Cdk5/p25 phosphorylation sites identified as biomarkers for Cdk5-driven neuroendocrine tumors (NETs) were detected in both slow and rapid onset models and were also histologically present in human MTC. Thus, this study directly relates mouse and human MTC models and uncovers vulnerable pathways potentially responsible for differential tumor growth rates. Functional validation of our findings may lead to better prediction of patient-specific personalized combinational therapies.

LIBRETTO-531: a phase III study of selpercatinib in multikinase inhibitor-naïve RET-mutant medullary thyroid cancer

Selpercatinib is a first-in-class, highly selective and potent, central nervous system-active RET kinase inhibitor. In the phase I/II trial, selpercatinib demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pre-treated and treatment-naive patients with RET-mutant medullary thyroid cancer (MTC). LIBRETTO-531 (NCT04211337) is a multicenter, open-label, randomized, controlled, phase III trial comparing selpercatinib to cabozantinib or vandetanib in patients with advanced/metastatic RET-mutant MTC. The primary objective is to compare progression-free survival (per RECIST 1.1) by blinded independent central review of patients with progressive, advanced, multikinase inhibitor-naive, RET-mutant MTC treated with selpercatinib versus cabozantinib or vandetanib. Key secondary objectives are to compare other efficacy outcomes (per RECIST 1.1) and tolerability of selpercatinib versus cabozantinib or vandetanib.

PET-CT in Clinical Adult Oncology-V. Head and Neck and Neuro Oncology

Simple Summary

Positron emission tomography (PET), typically combined with computed tomography (CT) has become a critical advanced imaging technique in oncology. With PET-CT, a radioactive molecule (radiotracer) is injected in the bloodstream and localizes to sites of tumor because of specific cellular features of the tumor that accumulate the targeting radiotracer. The CT scan, performed at the same time, provides information to facilitate attenuation correction, so that radioactivity from deep or dense structures can be better visualized, but with head and neck malignancies it is critical to provide correlating detailed anatomic imaging. PET-CT has a variety of applications in oncology, including staging, therapeutic response assessment, restaging, and surveillance. This series of six review articles provides an overview of the value, applications, and imaging and interpretive strategies of PET-CT in the more common adult malignancies. The fifth report in this series provides a review of PET-CT imaging in head and neck and neuro oncology.

Abstract

PET-CT is an advanced imaging modality with many oncologic applications, including staging, assessment of response to therapy, restaging, and longitudinal surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, and the potential pitfalls and nuances that characterize these applications. In addition, key tumor-specific clinical information and representative PET-CT images are provided to outline the role that PET-CT plays in the management of oncology patients. Hundreds of different types of tumors exist, both pediatric and adult. A discussion of the role of FDG PET for all of these is beyond the scope of this review. Rather, this series of articles focuses on the most common adult malignancies that may be encountered in clinical practice. It also focuses on FDA-approved and clinically available radiopharmaceuticals, rather than research tracers or those requiring a local cyclotron. The fifth review article in this series focuses on PET-CT imaging in head and neck tumors, as well as brain tumors. Common normal variants, key anatomic features, and benign mimics of these tumors are reviewed. The goal of this review article is to provide the imaging professional with guidance in the interpretation of PET-CT for the more common head and neck malignancies and neuro oncology, and to inform the referring providers so that they can have realistic expectations of the value and limitations of PET-CT for the specific type of tumor being addressed.

Successful Treatment with Selpercatinib for Ectopic Cushing's Syndrome Due to Medullary Thyroid Cancer

Selpercatinib, a RET kinase inhibitor, is an effective treatment for patients with medullary thyroid cancer with RET mutations. In this paper, we present the case of a 62-year-old man with ectopic Cushing’s syndrome due to medullary thyroid cancer who received treatment with selpercatinib. Six months later, all the cushingoid features had resolved, and s-calcitonin had decreased from 580 pmol/L to 3.5 pmol/L (normal < 3). After further 6 months, s-calcitonin had normalized (1.5 pmol/L), and radiological evaluation showed a profound tumour volume reduction. We are aware of two other cases where treatment with selpercatinib has also been successful. Thus, selpercatinib may be a promising treatment alternative in patients with ectopic Cushing’s syndrome due to medullary thyroid cancer, especially when other treatment options are ineffective or not tolerated.

Stereotactic radiotherapy is a useful treatment option for patients with medullary thyroid cancer

The role of radiotherapy in advanced medullary thyroid carcinoma (MTC) is confined to patients in whom surgical treatment or the administration of tyrosine kinase inhibitors are not possible or contraindicated. High fractionated radiation doses during radiosurgery or fractionated stereotactic radiotherapy are applied to reduce cancer-related symptoms and stabilize irradiated lesions. This study aimed to retrospectively evaluate the therapeutic effect of stereotactic radiotherapy in MTC patients.

MATERIAL AND METHODS

The study group involved 11 MTC patients, treated due to 16 cancer lesions, mainly bone metastases (10 lesions), lymph node (2 lesions) metastases, or liver metastases (2 lesions), one primary thyroid tumor, and one MTC recurrence in the thyroid bed. The fractionated and total radiation doses ranged between 5 and 12 Gy and 8-44 Gy, respectively. Six lesions were treated with a single radiation fraction, three lesions with 2 fractions, another 6 lesions with 3 fractions, whereas the remaining one metastatic lesion with 9 fractions of stereotactic radiosurgery.

RESULTS

The beneficial effect of stereotactic radiosurgery was obtained in all treated lesions. None of treated lesions progressed in the further disease course. Fourteen lesions were stable (87.5 %), including eight lesions showing progression before radiosurgery (good response). Disease control was obtained in all soft-tissue metastases. Regarding bone metastases, partial regression was achieved in 20 % lesions, whereas in 30 % lesions progressive before radiotherapy, the treatment led to disease stabilization.

CONCLUSIONS

Our data pointed to the effectiveness of high-dose fractionated radiotherapy in MTC. However, an observation of a larger group of patients is required to confirm it.

Selective Antitumor Activity of Datelliptium toward Medullary Thyroid Carcinoma by Downregulating RET Transcriptional Activity

Simple Summary

Medullary thyroid carcinoma (MTC) is a rare aggressive type of thyroid cancer with a propensity for metastasizing to the lymph nodes, liver, bones, and lungs. Previous studies have demonstrated that activated REarranged during Transfection (RET) mutants are key regulators of invasive and metastatic behaviors in MTC. The present study aimed to evaluate the antiinvasive and antimetastatic potential of a novel RET transcription inhibitor, datelliptium, which stabilizes the RET G-quadruplex structures and suppresses RET oncogene transcription by examining its effects on epithelial-to-mesenchymal transition (EMT), cancer stem cells (CSCs), and MTC cell migration. Interestingly, the ablation of RET with datelliptium resulted in decreased EMT, spheroid formation, and MTC cell migration. In this study, we also demonstrated the in vivo antitumor activity in TT tumor-bearing mice with about 75% tumor growth inhibition.

Abstract

Medullary thyroid carcinoma (MTC) is a rare aggressive form of thyroid cancer with high rates of metastasis. Sporadic and hereditary MTC are strongly driven by somatic and germline mutations, respectively, in the transmembrane REarranged during Transfection (RET) proto-oncogene, which encodes a receptor tyrosine kinase. Our previous study identified datelliptium as a novel RET transcription inhibitor, which stabilizes the RET G-quadruplex structures and suppresses RET oncogene transcription. The present study aimed to elucidate the effect of datelliptium on the suppression of epithelial-to-mesenchymal transition (EMT) and metastasis-related behaviors of MTC cells, including cell migration and formation of cancer stem cells (CSCs). Our results demonstrated that datelliptium downregulated the expression of the mesenchymal markers, including N-cadherin, vimentin, slug, snail, and claudin-1. Compared to untreated cells, datelliptium significantly decreased the migration of TT cells in a dose-dependent manner in a wound healing assay. Additionally, datelliptium significantly reduced the size of preformed spheroids from TT cells over the time course. Finally, datelliptium inhibited approximately 75% of MTC xenograft growth with minimal systemic toxicity. In conclusion, datelliptium exerts its antitumor activity against MTC cells by reducing the EMT program, migratory ability, and self-renewal capacity of TT cells, thus preventing invasive and metastatic behavior of MTC.

How I treat medullary thyroid cancer

Medullary thyroid cancer (MTC) represents a rare neuroendocrine neoplasm originating from neoplastic C-cells in the thyroid gland. While localized disease is potentially curable with an optimized surgical approach, the number of relapses is high, and a considerable number of patients present with primary metastatic disease. Multidisciplinary management including standardized surveillance following surgery, but also early involvement of medical oncologists, is therefore important. Several oncogenic pathways are involved in the pathogenesis of MTC including vascular endothelial growth factor receptor, epidermal growth factor receptor, MET, and most importantly RET, and the multi-tyrosine kinase inhibitors vandetanib and cabozantinib have been approved for advanced MTC based on data from phase III studies. As activating RET mutations represent the most important driver, specific RET inhibitors were introduced and suggest high response rates with limited off-target toxicities. The current review provides a practical overview on clinical presentation and management from early to advanced MTC.

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Systemic treatment options in advanced MTC remain limited with particularly immunotherapy being ineffective.

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Multi-tyrosine kinase inhibitors remain the standard of care for advanced MTC.

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Recent approval of selective RET inhibitors is promising.

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Testing of RET mutations should be included routinely into the diagnostic algorithm.

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Multidisciplinary teams should be involved to guarantee the best outcome for our patients.

Emerging Roles of Circular RNAs in Thyroid Cancer

Thyroid cancer (TC) has the highest incidence among endocrine malignancies. Thus, it is essential to achieve a deep understanding of various mechanisms of development and progression of TC. circRNAs are recognized by multiple studies as being dysregulated in TC. Accumulating evidences have revealed that circRNAs serve as regulatory molecules involved in various biological processes in TC, including cell proliferation, apoptosis, invasion/migration, metabolism, and chemoresistance. Furthermore, circRNA can also serve as an effective tool in TC researches of diagnosis, prognosis, and treatments. Thus, this review is to outline the characteristics of circRNAs, generalize their categories and functions, and highlight the expression of circRNAs in TC. Meanwhile, we are expecting to achieve a comprehensive understanding of new therapies based on circRNAs in treating or preventing TC.

YAP confers resistance to vandetanib in medullary thyroid cancer

Medullary thyroid cancer (MTC) is the third most common thyroid cancer. RET (Rearranged in Transformation) gene mutations are considered as one of the major drivers of MTC. Vandetanib suppresses RET activity, and has shown promise in clinical trials. Unfortunately, acquired resistance to vandetanib has been observed in MTC, although the mechanism was largely unknown. We investigated the critical role of YAP (Yes-Associated Protein) on vandetanib resistance in MTC. For this, TT cells (medullary thyroid cancer cells) were treated with vandetanib for 3 months to generate a vandetanib-resistant cell line (TT-R). We investigated the role of YAP on vandetanib-resistance in TT-R cells by performing cell proliferation and colony formation assays, and examined the antitumor effects of YAP inhibitor and vandetanib in a mouse model of xenografted MTC. The TT-R cells displayed 6-fold higher IC₅₀ to vandetanib than the TT cells. Overexpression of YAP resulted in resistance to vandetanib, whereas knockdown of YAP re-sensitized the TT-R cells to vandetanib. The YAP inhibitor synergized with vandetanib on tumor inhibition. Our results suggest that YAP plays an important role in acquired resistance to vandetanib in MTC, providing basis for combating MTC with YAP inhibitor and vandetanib.

Silencing of zinc finger protein 703 inhibits medullary thyroid carcinoma cell proliferation in vitro and in vivo

Zinc finger protein 703 (ZNF703) is a new member of the zinc finger protein family of transcription factors that plays an important role during embryogenesis in metazoans. The overexpression of ZNF703 contributes to tumorigenesis and progression of a number of malignancies by activating the Akt/mammalian target of rapamycin (mTOR) signaling pathway. This pathway is activated in medullary thyroid cancer (MTC), but its mechanism of action is not yet fully understood. The aim of the present study was to examine the role of ZNF703 and its association with Akt/mTOR activation in MTC. The present study used the phosphorylation of Akt1 protein at serine 473 (pAkt⁴⁷³) as an indicator of signaling activation. Immunohistochemistry (IHC) staining and western blot analyses were performed in order to examine the expression of ZNF703 in 34 cases of MTC and 12 cases of corresponding normal thyroid tissues. ZNF703 expression in MTC was significantly higher compared with the corresponding normal thyroid tissues (P<0.05). Furthermore, expression of ZNF703 was associated with tumor size, lymph node metastasis and advanced stage of disease. IHC also demonstrated that the level of ZNF703 was positively correlated with p-Akt⁴⁷³ in the 34 cases of MTC. The human MTC cell line TT was selected for further investigation as TT cells exhibit Akt/mTOR activation. The biological effects of silencing ZNF703 in TT cells on proliferation and apoptosis, both in vitro and in vivo were investigated in the present study. ZNF703 silencing inhibited the proliferation of TT cells in vitro and inhibited xenograft tumor growth in vivo. These effects were accompanied by the substantial decrease of pAkt⁴⁷³ and the induction of p53 protein. These results demonstrate that ZNF703 may play a relevant role in MTC due to its association with the Akt/mTOR signaling pathway.

The role of postoperative adjuvant radiotherapy in the local control in medullary thyroid carcinoma

BACKGROUND

The value of postoperative radiotherapy in the treatment of medullary thyroid carcinoma (MTC) has not been unequivocally demonstrated. Therefore our study aimed to answer the question of whether adjuvant radiotherapy showed any impact on the risk of local recurrence and whether there were any differences in response to radiotherapy between hereditary and sporadic MTC.

METHODS

A retrospective analysis involved 254 MTC patients, among them 73 patients with a hereditary disease. Two hundred and twenty-four patients, including 43 persons at high risk of local relapse, underwent only initial surgery, 18 other patients were operated due to MTC recurrences, whereas the remaining 12 patients had cytoreductive procedure or were not amenable for surgery. Radiotherapy was carried out in 132 patients. One hundred and twenty patients underwent adjuvant radiotherapy, among them 102 patients after initial surgery. The median follow up was 10 years (range 0.5-29 years).

RESULTS

Local recurrence occurred in 107/254 patients, among them in 63 subjects after prior radiotherapy. The frequency of relapse showed significant, increasing trend toward higher MTC stages (p<0.001). More relapses were noticed in patients with lymph node metastases at diagnosis. Adjuvant radiotherapy was associated with a lower risk of nodal recurrence only in high-risk patients, particularly if lymph node metastases were present at MTC diagnosis. The differences between hereditary and sporadic subgroups were not significant.

CONCLUSIONS

Adjuvant radiotherapy has a limited importance in MTC treatment. It should be considered in high-risk MTC patients. The presence of RET mutation does not influence the response to radiation.

Leveraging Atropisomerism to Obtain a Selective Inhibitor of RET Kinase with Secondary Activities toward EGFR Mutants

Unstable atropisomerism is innate in many common scaffolds in drug discovery, commonly existing as freely rotating aryl-aryl bonds. Such compounds can access the majority of dihedral conformations around the bond axis; however, most small molecules bind their target within a narrow range of these available conformations. The remaining accessible conformations can interact with other proteins leading to compound promiscuity. Herein, we leverage atropisomerism to restrict the accessible low-energy dihedral conformations available to a promiscuous kinase inhibitor and achieve highly selective and potent inhibitors of the oncogenic target rearranged during transfection (RET) kinase. We then evaluate our lead inhibitor against kinases that were predicted to bind compounds in a similar conformational window to RET, discovering a potent inhibitor of drug-resistant epidermal growth factor receptor (EGFR) mutants including L858R/T790M/C797S EGFR. Leveraging atropisomerism to restrict accessible conformational space should be a generally applicable strategy due to the prevalence of unstable atropisomerism in drug discovery.

No Evidence of Increase in Calcitonin Concentrations or Development of C-Cell Malignancy in Response to Liraglutide for Up to 5 Years in the LEADER Trial

OBJECTIVE

To describe the changes in serum levels of calcitonin in liraglutide- and placebo-treated patients in the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results-A Long Term Evaluation (LEADER) trial over a 3.5-5-year period.

RESEARCH DESIGN AND METHODS

Patients (n = 9,340) with type 2 diabetes and high risk for cardiovascular events were randomized 1:1 to liraglutide or placebo. We analyzed calcitonin levels, thyroid and C-cell adverse events, and neoplasms.

RESULTS

At 36 months, patients randomized to liraglutide versus placebo showed no evidence of increase in calcitonin concentrations in male (estimated treatment ratio [ETR] 1.03 [95% CI 1.00, 1.06]; P = 0.068) and female (ETR 1.00 [95% CI 0.97, 1.02]; P = 0.671) subgroups. There were no episodes of C-cell hyperplasia or medullary thyroid carcinoma in liraglutide-treated patients.

CONCLUSIONS

There was no evidence of a difference in calcitonin concentrations between the liraglutide and placebo groups, and no C-cell malignancies occurred in the liraglutide group.

Translational Diagnostics and Therapeutics in Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNET) are rare tumors, but have been increasing in incidence. Although typically thought of as indolent, more than half of patients present with metastatic disease. For many years, the only mutations commonly known in these tumors were those in the MEN1 gene. Recently, the genetics underlying PNETs have been further defined through exome sequencing. The most frequent alterations found in sporadic PNETs are in MEN1, DAXX/ATRX, and a variety of genes in the mTOR pathway. Confirmation of these mutations has prompted trials with a number of drugs active in these pathways, and two drugs were eventually approved in 2011-sunitinib and everolimus. New data additionally identify the MET and CD47 receptors as potential novel drug targets. Yet despite improvements in progression-free survival with sunitinib and everolimus, further studies defining when to use these agents and factors associated with limitations in their utility are needed. As more discoveries are made in the laboratory that elucidate additional molecular mechanisms important in the initiation and metastasis of PNETs, continued efforts to translate these discoveries into distinct new therapies will be needed to improve patient survival. Clin Cancer Res; 22(20); 5022-9. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "ENDOCRINE CANCERS REVISING PARADIGMS".

Recurrent Metastatic Medullary Thyroid Carcinoma: A Case of Sustained Response to Prolonged Treatment with Somatostatin Analogues

BACKGROUND

Medullary thyroid carcinoma (MTC) is a rare disease. Treatment options for recurrent disease are limited. Although somatostatin analogues might have a role as anticancer agents in MTC, the evidence is inconclusive.

PATIENT FINDINGS

A 64-year-old male was diagnosed with MTC in January 2010. Total thyroidectomy with neck dissection (stage IVA, pT2pN1bM0, R1) was performed, followed by adjuvant locoregional radiotherapy. Two years later, in January 2012, the patient developed recurrent metastatic disease, evidenced by elevated carcinoembryonic antigen (CEA) and calcitonin levels, and a positive uptake (Octreoscan^®) in the right adrenal gland and pancreatic head. A further computed tomography (CT) scan revealed metastases in the right adrenal gland, the duodenal bulb, and two pancreatic lesions, which were later confirmed as metastases by endoscopic ultrasound and cytology, and therefore salvage surgery was ruled out. Treatment with Somatuline Autogel^® (120 mg subcutaneously every 28 days) was initiated in September 2012, and 11 months later, calcitonin and CEA levels had both normalized, and a new CT scan showed that the metastatic lesions had disappeared or shrunk markedly. An Octreoscan performed in January 2014 and a repeat contrast-enhanced CT in February 2014 showed sustained tumor response. The patient remained in remission until February 2016, when a new Octreoscan revealed recurrent disease in the right adrenal gland, a nodule in the right upper pulmonary lobe, and nodal disease in the celiac trunk. CEA and calcitonin levels remained normal, although with a slight increase in calcitonin levels (47 pg/mL).

SUMMARY

The unusual case is described of a patient with metastatic MTC involving the adrenal gland, duodenum, and pancreas, who achieved a sustained response to somatostatin analogues after 11 months of treatment. The patient remained in remission for nearly 3.5 years from initiation of treatment with somatostatin analogues.

CONCLUSIONS

The case presented here is one of the few described in the literature in which long-term treatment with somatostatin analogues resulted in a sustained tumor response in a patient with metastatic recurrent MTC following curative-intent surgery. These findings suggest that prolonged treatment with somatostatin analogues may be beneficial in asymptomatic cases with a low tumor burden and a positive Octreoscan following recurrence. More data are needed to confirm these findings.

Uncommon response of cisplatin and etoposide for treatment of advanced medullary thyroid carcinoma

Systemic treatment of Medullary thyroid carcinoma (MTC) is currently limited to the use of a tyrosine kinase inhibitor. Cytotoxic chemotherapy is not routinely recommended in the earlier lines of treatment due to the lack of efficacy. We describe a patient with locally advanced MTC who had an uncommon response to cisplatin and etoposide.

Therapeutic effects of adenovirus-mediated CD and NIS expression combined with Na131I/5-FC on human thyroid cancer

Thyroid cancer is the most common type of malignant endocrine tumor diagnosed. Previous studies have indicated that gene therapy is the most promising and effective therapeutic method for thyroid cancer. Therefore, in the present study, Na¹³¹I/5-fluorocytosine (5-FC) treatment was combined with cytosine deaminase (CD, encoded by the CDA gene) and sodium iodide symporter (NIS, encoded by the SLC5A5 gene) to act together as a therapeutic tool for thyroid cancer. The present study explored the combined cytotoxic effects of adenovirus-mediated CD and NIS under the control of the progression elevated gene-3 (PEG-3) promoter (Ad-PEG-3-CD-NIS) with Na¹³¹I/5-FC against the human thyroid cancer TT cell line in vitro. The PEG-3 fragment was obtained by polymerase chain reaction (PCR) using rat genomic DNA as the template, and then Ad-PEG-3-CDA-SLC5A5 was constructed using XbaI. TT cells were transfected by recombinant adenovirus. The method of reverse transcription-quantitative PCR was performed to test the expression of CD and NIS at the level of transcription. The morphological change was assessed by fluorescence microscopy and investigated by western blot analysis. An MTT assay was used to determine the number of living cells inhibited by single or combination therapies on TT cells. The results indicated that the PEG-3 was successfully cloned, and was also positively regulated in 293 cells. CDA and SLC5A5 genes were highly expressed in TT cells. Na¹³¹I combined with 5-FC significantly decreased the human thyroid cancer cells. In conclusion, combination therapy of Ad-PEG3-CDA-SLC5A5 and Na¹³¹I/5-FC induces significantly more apoptotic characteristics than either single treatment with Ad-PEG-3-CDA-SLC5A5 or Na¹³¹I/5-FC, and low doses of Ad-PEG-3-CDA-SLC5A5 enhanced the cytotoxic effects.

Targeted Therapy for Medullary Thyroid Cancer: A Review

Medullary thyroid cancers (MTCs) constitute between 2 and 5% of all thyroid cancers. The 10-year overall survival (OS) rate of patients with localized disease is around 95% while that of patients with regional stage disease is about 75%. Only 20% of patients with distant metastases at diagnosis survive 10 years which is significantly lower than for differentiated thyroid cancers. Cases with regional metastases at presentation have high recurrence rates. Adjuvant external radiation confers local control but not improved OS. The management of residual, recurrent, or metastatic disease till a few years ago was re-surgery with local measures such as radiation. Chemotherapy was used with marginal benefit. The development of targeted therapy has brought in a major advantage in management of such patients. Two drugs—vandetanib and cabozantinib—have been approved for use in progressive or metastatic MTC. In addition, several drugs acting on other steps of the molecular pathway are being investigated with promising results. Targeted radionuclide therapy also provides an effective treatment option with good quality of life. This review covers the rationale of targeted therapy for MTC, present treatment options, drugs and methods under investigation, as well as an outline of the adverse effects and their management.

Selective Ablation of Tumor Suppressors in Parafollicular C Cells Elicits Medullary Thyroid Carcinoma

Among the four different types of thyroid cancer, treatment of medullary thyroid carcinoma poses a major challenge because of its propensity of early metastasis. To further investigate the molecular mechanisms of medullary thyroid carcinoma and discover candidates for targeted therapies, we developed a new mouse model of medullary thyroid carcinoma based on our CGRPCreER mouse line. This system enables gene manipulation in parafollicular C cells in the thyroid, the purported cells of origin of medullary thyroid carcinoma. Selective inactivation of tumor suppressors, such as p53, Rb, and Pten, in mature parafollicular C cells via an inducible Cre recombinase from CGRPCreER led to development of murine medullary thyroid carcinoma. Loss of Pten accelerated p53/Rb-induced medullary thyroid carcinoma, indicating interactions between pathways controlled by tumor suppressors. Moreover, labeling differentiated parafollicular C cells by CGRPCreER allows us to follow their fate during malignant transformation to medullary thyroid tumor. Our findings support a model in which mutational events in differentiated parafollicular C cells result in medullary thyroid carcinoma. Through expression analysis including RNA-Seq, we uncovered major signaling pathways and networks that are perturbed following the removal of tumor suppressors. Taken together, these studies not only increase our molecular understanding of medullary thyroid carcinoma but also offer new candidates for designing targeted therapies or other treatment modalities.

MiR-182 promotes cancer invasion by linking RET oncogene activated NF-κB to loss of the HES1/Notch1 regulatory circuit

Background

Dominant-activating mutations in the RET proto-oncogene, a receptor tyrosine kinase, are responsible for the development of medullary thyroid carcinoma (MTC) and causative for multiple endocrine neoplasia (MEN) type 2A and 2B. These tumors are highly aggressive with a high propensity for early metastasis and chemoresistance. This attribute makes this neoplasia an excellent model for probing mechanisms underlying cancer progression.

Methods

The expression level of miR-182 was measured in MTC tumor specimens and in TT cells by real-time RT-PCR. TT cells and modified NThy-ori 3.1 that stably express RETM918T were used to investigate RET-dependent regulation of miR-182. Identification and validation of miR-182 targets and pathways was accomplished with luciferase assays, qRT-PCR, Western blotting and immunofluorescence. In vitro, overexpression and knockdown experiments were carried out to examine the impact of miR-182 and HES1 on invasion and migration.

Results

We found that miR-182 expression is significantly upregulated in MTC patient samples and tumor-derived cell lines harboring mutated RET. Inhibition of RET oncogenic signaling through a dominant-negative RET∆TK mutant in TT cells reduces miR-182, whereas overexpression of RETM918T in NThy-ori 3.1 cells increases miR-182 levels. We further show that overexpression of this miRNA in NThy.miR-182 cells promotes the invasive and migratory properties without affecting cell proliferation. MiR-182 is upregulated after RET induced NF-κB translocation into the nucleus via binding of NF-κB to the miR-182 promoter. Database analysis revealed that HES1, a repressor of the Notch pathway, is a target of miR-182, whose upregulation correlates with loss of HES1 transcription in MTC tissue samples and mutant RET cell lines. Moreover, we demonstrated that the 3′UTR of the HES1 mRNA bearing the targeting sequence for miR-182 clearly reduced luciferase reporter activity in cells expressing miR-182. Decreased expression of HES1 promotes migration by upregulating Notch1 inhibitor Deltex1 and consequent repression of Notch1.

Conclusion

We demonstrate a novel mechanism for MTC aggressiveness in which mutated RET/NF-κB-driven expression of miR-182 impedes HES1 activation in a negative feedback loop. This observation might open new possibilities to treat RET oncogene associated metastatic cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0563-x) contains supplementary material, which is available to authorized users.

Detection of Molecular Alterations in Medullary Thyroid Carcinoma Using Next-Generation Sequencing: an Institutional Experience

Medullary thyroid carcinoma (MTC) harbors rearranged during transfection (RET) gene and rarely RAS gene mutations. The knowledge of the type of gene mutation in MTC is important to determine the treatment of the patients and the management of their family members. Targeted next-generation sequencing with a panel of 47 genes was performed in a total of 12 cases of sporadic (9/12) and hereditary MTC (3/12). Two of three hereditary MTCs had RET/C634R mutation, while the other one harbored two RET mutations (L790F and S649L). All the sporadic MTC had RET/M918T mutation except one case with HRAS mutation. Next-generation sequencing (NGS) can provide comprehensive analysis of molecular alterations in MTC in a routine clinical setting, which facilitate the management of the patient and the family members.

Unusual gastric mucosal infiltration by a medullary thyroid carcinoma: a case report

Background

Medullary thyroid carcinoma accounts for approximately 1 to 2 % of all thyroid carcinoma cases. The most common route of dissemination is to locoregional lymph nodes. Distant metastases commonly affect bones, lungs, and liver. We present a case of a white woman with a 25-year history of medullary thyroid carcinoma on multiple medications including tyrosine kinase inhibitor therapy for the last 11 months, who exhibited unusual diffuse infiltration of advanced stage medullary thyroid carcinoma to her gastric mucosa.

Case presentation

A 53-year-old white woman presented with increasing fatigue, loss of appetite, and severe epigastric pain radiating to her back. She had a history of medullary thyroid carcinoma (pT2pN1b), diagnosed 25 years ago and treated by complete thyroidectomy and repeated bilateral cervical lymph node dissection. Medical therapy included octreotide 20 mg every 4 weeks, which was switched to the tyrosine kinase inhibitor vandetanib 300 mg/day 11 months ago when computed tomography scanning revealed progressive mediastinal lymph node and diffuse and symptomatic pulmonary metastases. Of note, she demonstrated macroscopically stable pulmonary and mediastinal lymph node metastases; however, her calcitonin serum levels dramatically increased. Computed tomography scanning revealed a single new intrahepatic lesion (4 mm) as well as multiple (>10) new supraclavicular lesions suggestive of medullary thyroid carcinoma progress. As proven by gastric biopsy and immunohistochemical evaluation, her epigastric pain was explained by a diffuse infiltration of her gastric mucosa by metastatic medullary thyroid carcinoma. Subsequently, she rapidly deteriorated and died.

Conclusions

The current case report shows for the first time an unusual metastatic infiltration of the gastric mucosa by medullary thyroid carcinoma. When treating these patients, it is important to include this differential diagnosis during follow-up.

Electronic supplementary material

The online version of this article (doi:10.1186/s13256-016-0981-9) contains supplementary material, which is available to authorized users.

Genetic and epigenetic factors affect RET gene expression in breast cancer cell lines and influence survival in patients

Germline and somatic mutations play a crucial role in breast cancer (BC), driving the initiation, progression, response to therapy and outcome of the disease. Hormonal therapy is limited to patients with tumors expressing steroid hormone receptors, such as estrogen receptor (ER), nevertheless resistance often limits its success.The RET gene is known to be involved in neurocristopathies such as Hirschsprung disease and Multiple Endocrine Neoplasia type 2, in the presence of loss-of-function and gain-of-function mutations, respectively. More recently, RET over-expression has emerged as a new player in ER-positive (ER+) BC, and as a potential target to enhance sensitivity and avoid resistance to tamoxifen therapy.Therefore, targeting the RET pathway may lead to new therapies in ER+ BC. To this end, we have investigated the molecular mechanisms which underlie RET overexpression and its possible modulation in two BC cell lines, MCF7 and T47D, showing different RET expression levels. Moreover, we have carried out a pilot association study in 93 ER+ BC patients. Consistent with the adverse role of RET over-expression in BC, increased overall survival was observed in carriers of the variant allele of SNP rs2435357, a RET polymorphism already known to be associated with reduced RET expression.

Multimodal imaging with (18)F-FDG-PET/CT and (111)In-Octreotide SPECT in patients with metastatic medullary thyroid carcinoma

OBJECTIVE

The aim of our study was to determine the role of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG-PET/CT) and indium-111 Octreotide single photon emission tomography ((111)In-Octreotide SPECT) in the evaluation of metastatic medullary thyroid carcinoma (MMTC).

METHODS

Twenty-five MMTC patients were retrospectively evaluated. All patients had undergone whole-body (18)F-FDG-PET/CT including 20 who had also undergone (111)In-Octreotide SPECT within a maximum interval of 6 weeks. Diagnostic contrast-enhanced computed tomography (CT) alone or as part of (18)F-FDG-PET/CT examination was performed in all patients.

RESULTS

Contrast-enhanced CT detected a total of 131 lesions including 79 enlarged lymph nodes and 14 bone lesions. (18)F-FDG-PET/CT visualized a total of 92 true positive lesions (SUVmax range 1.1-10.0, mean 4.0 ± 1.7) including 66 lymph nodes, 7 of which were not enlarged on CT, and 8 bone metastases. In the 20 patients studied with both techniques, a total of 64 and 46 true positive lesions were detected by (18)F-FDG-PET/CT and (111)In-Octreotide SPECT, respectively. In particular, (18)F-FDG uptake was found in 43 lymph nodes and in 7 bone metastases whereas (111)In-Octreotide uptake was detected in 27 lymph nodes and in 10 bone metastases.

CONCLUSIONS

In MMTC patients, (18)F-FDG-PET/CT provides a useful contribution mainly in evaluating lymph node involvement whereas (111)In-Octreotide SPECT can contribute to the detection and somatostatin receptor characterization especially of bone lesions.

Sorafenib in the treatment of thyroid cancer

Sorafenib has been evaluated in several Phase II and III studies in patients with locally advanced/metastatic radioactive iodine-refractory differentiated thyroid carcinomas (DTCs), reporting partial responses, stabilization of the disease and improvement of progression-free survival. Best responses were observed in lung metastases and minimal responses in bone lesions. On the basis of these studies, sorafenib was approved for the treatment of metastatic DTC in November 2013. Few studies suggested that reduction of thyroglobulin levels, or of average standardized uptake value at the fluorodeoxyglucose-PET, could be helpful for the identification of responding patients; but further studies are needed to confirm these results. Tumor genetic marker levels did not have any prognostic or predictive role in DTC patients.The most common adverse events observed included skin toxicity and gastrointestinal and constitutional symptoms. Encouraging results have also been observed in patients with medullary thyroid cancer. Many studies are ongoing to evaluate the long-term efficacy and tolerability of sorafenib in DTC patients.