Epidermal Growth Factor Receptor as a Novel Therapeutic Target in Anaplastic Thyroid Carcinomas

Anaplastik tiroid kanseri hücre hattının morfolojik analizi

Aim: Thyroid follicular cell derived cancers are classified into three groups such as papillary thyroid cancer (85%), follicular thyroid cancer (12%) and anaplastic (undifferentiated) thyroid cancer (ATC) (3%). ATCs have very rapid course, poor treatment outcomes and they are very aggressive. The aim of current study was to assess the analysis of the morphological differences of ATC cell line with the normal thyroid cell line (NTC). Materials and Methods: NTH and ATC cells were examined with haematoxylin and eosin, the nucleus: cytoplasm (N:C) ratios were detected, and cell cycles were investigated. These cell lines were compared according to their N:C ratio and their abundance in cell cycle phases. Results: The N:C ratio was higher in ATC than NTC. Both cell groups were mostly found in G0/G1 phase (68.4; 82.8) and have statistical difference in both G0/G1 and S phases. Conclusion: The rapid course and the rarity of ATC are significant barriers for clinical trials. Cultured cell lines are very important to explore the behaviour in the biology of ATC cells (such as the cell cycle), to understand the course of the disease, and to find an effective target for treatment.

The role of anlotinib-mediated EGFR blockade in a positive feedback loop of CXCL11-EGF-EGFR signalling in anaplastic thyroid cancer angiogenesis

BACKGROUND

Hypoxia-induced angiogenesis functions importantly in anaplastic thyroid cancer (ATC) progression. However, the therapeutic potential of broad-spectrum anti-angiogenic agent remains undefined. Anlotinib conventionally targets VEGFR, FGFR and PDGFR. Here, a novel role of anlotinib on ATC angiogenesis was illustrated.

METHODS

Molecular expressions were established via tissue microarray. Multiple assays (tubule formation, 3D sprouting and chicken chorioallantoic membrane model) were used for angiogenic evaluation. Panels of molecular screening were achieved by antibody and PCR arrays. The loop binding motif of EGFR for homology modelling was prepared using Maestro.

RESULTS

Anlotinib could dose- and time-dependently inhibit cell viability under normoxia and hypoxia and could repress hypoxia-activated angiogenesis more efficiently in vitro and in vivo. CXCL11 and phospho-EGFR were hypoxia-upregulated with a positive correlation. The cancer-endothelium crosstalk could be mediated by the positive CXCL11-EGF-EGFR feedback loop, which could be blocked by anlotinib directly targeting EGFR via a dual mechanism by simultaneous inhibitory effects on cancer and endothelial cells. The AKT-mTOR pathway was involved in this regulatory network.

CONCLUSIONS

The newly identified CXCL11-EGF-EGFR signalling provided mechanistic insight into the interaction between cancer and endothelial cells under hypoxia, and EGFR was a novel target. Anlotinib may be the encouraging therapeutic candidate in ATC.

Gold-Based Nanoplataform for the Treatment of Anaplastic Thyroid Carcinoma: A Step Forward

Anaplastic thyroid carcinoma (ATC) is a very rare subtype of thyroid carcinoma and one of the most lethal malignancies. Poor prognosis is mainly associated with its undifferentiated nature, inoperability, and failing to respond to the typically used therapies for thyroid cancer. Photothermal Therapy (PTT) entails using light to increase tissues' temperature, leading to hyperthermia-mediated cell death. Tumours are more susceptible to heat as they are unable to dissipate it. By using functionalized gold nanoparticles (AuNPs) that transform light energy into heat, it is possible to target the heat to the tumour. This study aims to formulate ATC-targeted AuNPs able to convert near-infrared light into heat, for PTT of ATC. Different AuNPs were synthetized and coated. Size, morphology, and surface plasmon resonances band were determined. The optimized coated-AuNPs were then functionalized with ligands to assess ATC's specificity. Safety, efficacy, and selectivity were assessed in vitro. The formulations were deemed safe when not irradiated (>70% cell viability) and selective for ATC. However, when irradiated, holo-transferrin-AuNPs were the most cytotoxic (22% of cell viability). The biodistribution and safety of this formulation was assessed in vivo. Overall, this novel formulation appears to be a highly promising approach to evaluate in a very near future.

Targeting Super-Enhancer-Driven Oncogenic Transcription by CDK7 Inhibition in Anaplastic Thyroid Carcinoma

Background: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies, with no effective treatment currently available. The molecular mechanisms of ATC carcinogenesis remain poorly understood. The objective of this study was to investigate the mechanisms and functions of super-enhancer (SE)-driven oncogenic transcriptional addiction in the progression of ATC and identify new drug targets for ATC treatments. Methods: High-throughput chemical screening was performed to identify new drugs inhibiting ATC cell growth. Cell viability assay, colony formation analysis, cell-cycle analysis, and animal study were used to examine the effects of drug treatments on ATC progression. Chromatin immunoprecipitation sequencing was conducted to establish a SE landscape of ATC. Integrative analysis of RNA sequencing, chromatin immunoprecipitation sequencing, and CRISPR/Cas9-mediated gene editing was used to identify THZ1 target genes. Drug combination analysis was performed to assess drug synergy. Patient samples were analyzed to evaluate candidate biomarkers of prognosis in ATC. Results: THZ1, a covalent inhibitor of cyclin-dependent kinase 7 (CDK7), was identified as a potent anti-ATC compound by high-throughput chemical screening. ATC cells, but not papillary thyroid carcinoma cells, are exceptionally sensitive to CDK7 inhibition. An integrative analysis of both gene expression profiles and SE features revealed that the SE-mediated oncogenic transcriptional amplification mediates the vulnerability of ATC cells to THZ1 treatment. Combining this integrative analysis with functional assays led to the discovery of a number of novel cancer genes of ATC, including PPP1R15A, SMG9, and KLF2. Inhibition of PPP1R15A with Guanabenz or Sephin1 greatly suppresses ATC growth. Significantly, the expression level of PPP1R15A is correlated with CDK7 expression in ATC tissue samples. Elevated expression of PPP1R15A and CDK7 are both associated with poor clinical prognosis in ATC patients. Importantly, CDK7 or PPP1R15A inhibition sensitizes ATC cells to conventional chemotherapy. Conclusions: Taken together, these findings demonstrate transcriptional addiction in ATC pathobiology and identify CDK7 and PPP1R15A as potential biomarkers and therapeutic targets for ATC.

Low intensity focused ultrasound (LIFU) triggered drug release from cetuximab-conjugated phase-changeable nanoparticles for precision theranostics against anaplastic thyroid carcinoma

This study provides an efficient theranostic strategy for concurrent targeted ultrasound molecular imaging and effective synergistic antitumor therapy.

Do Statins Affect Thyroid Volume and Nodule Size in Patients with Hyperlipidemia in a Region with Mild-to-Moderate Iodine Deficiency? A Prospective Study

OBJECTIVE

The objective of this study was to assess the antiproliferative pleiotropic effects of statins on thyroid function, volume, and nodularity.

SUBJECTS AND METHODS

One hundred and six hyperlipidemic patients were included in this prospective study. The 69 patients in the statin groups received atorvastatin (16 received 10 mg and 18 received 20 mg) or rosuvastatin (20 received 10 mg and 15 received 20 mg). The 37 patients in the control group, assessed as not requiring drugs, made only lifestyle changes. Upon admission and after 6 months, all patients were evaluated by ultrasonography as well as for lipid variables (total cholesterol, high- and low-density lipoprotein cholesterol, and triglycerides) and thyroid function and structure.

RESULTS

After 6 months, no differences in thyroid function, thyroid volume, the number of thyroid nodules, or nodule size were observed in the statin and control groups. In a subgroup analysis, total thyroid volume had decreased more in patients receiving 20 mg of rosuvastatin than that in the control group (p < 0.05). Maximum nodule size had decreased more in those receiving 10 mg of rosuvastatin (p < 0.05).

CONCLUSIONS

Our results suggest an association between rosuvastatin treatment and smaller thyroid volume and maximum nodule diameter; this could be attributable to the antiproliferative effects of statin therapy on the thyroid.

Carfilzomib potentiates CUDC-101-induced apoptosis in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most aggressive human malignancies, with no effective treatment currently available. Previously, we identified agents active against ATC cells, both in vitro and in vivo, using quantitative high-throughput screening of 3282 clinically approved drugs and small molecules. Here, we report that combining two of these active agents, carfilzomib, a second-generation proteasome inhibitor, and CUDC-101, a histone deacetylase and multi-kinase inhibitor, results in increased, synergistic activity in ATC cells. The combination of carfilzomib and CUDC-101 synergistically inhibited cellular proliferation and caused cell death in multiple ATC cell lines harboring various driver mutations observed in human ATC tumors. This increased anti-ATC effect was associated with a synergistically enhanced G2/M cell cycle arrest and increased caspase 3/7 activity induced by the drug combination. Mechanistically, treatment with carfilzomib and CUDC-101 increased p21 expression and poly (ADP-ribose) polymerase protein cleavage. Our results suggest that combining carfilzomib and CUDC-101 would offer an effective therapeutic strategy to treat ATC.

Anaplastic thyroid carcinoma: from clinicopathology to genetics and advanced therapies

Anaplastic thyroid carcinoma (ATC) is a rare malignancy, accounting for 1-2% of all thyroid cancers. Although rare, ATC accounts for the majority of deaths from thyroid carcinoma. ATC often originates in a pre-existing thyroid cancer lesion, as suggested by the simultaneous presence of areas of differentiated or poorly differentiated thyroid carcinoma. ATC is characterized by the accumulation of several oncogenic alterations, and studies have shown that an increased number of oncogenic alterations equates to an increased level of dedifferentiation and aggressiveness. The clinical management of ATC requires a multidisciplinary approach; according to recent American Thyroid Association guidelines, surgery, radiotherapy and/or chemotherapy should be considered. In addition to conventional therapies, novel molecular targeted therapies are the most promising emerging treatment modalities. These drugs are often multiple receptor tyrosine kinase inhibitors, several of which have been tested in clinical trials with encouraging results so far. Accordingly, clinical trials are ongoing to evaluate the safety, efficacy and effectiveness of these new agents. This Review describes the updated clinical and pathological features of ATC and provides insight into the molecular biology of this disease. The most recent literature regarding conventional, newly available and future therapies for ATC is also discussed.

Dual inhibition of HDAC and EGFR signaling with CUDC-101 induces potent suppression of tumor growth and metastasis in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most lethal human malignancies that currently has no effective therapy. We performed quantitative high-throughput screening (qHTS) in three ATC cell lines using 3,282 clinically approved drugs and drug candidates, and identified 100 active agents. Enrichment analysis of active compounds showed that inhibitors of EGFR and histone deacetylase (HDAC) were most active. Of these, the first-in-class dual inhibitor of EGFR, HER2 and HDACs, CUDC-101, had the highest efficacy and lower IC₅₀ than established drugs. We validated that CUDC-101 inhibited cellular proliferation and resulted in cell death by inducing cell cycle arrest and caspase-dependent apoptosis. CUDC-101 also inhibited cellular migration in vitro. Mechanistically, CUDC-101 inhibited MAPK signaling and histone deacetylation in ATC cell lines with multiple driver mutations present in human ATC. The anticancer effect of CUDC-101 was associated with increased expression of p21 and E-cadherin, and reduced expression of survivin, XIAP, β-catenin, N-cadherin, and Vimentin. In an in vivo mouse model of metastatic ATC, CUDC-101 inhibited tumor growth and metastases, and significantly prolonged survival. Response to CUDC-101 treatment in vivo was associated with increased histone 3 acetylation and reduced survivin expression. Our findings provide a preclinical basis to evaluate CUDC-101 therapy in ATC.

Involvement of cysteine-rich protein 61 in the epidermal growth factor-induced migration of human anaplastic thyroid cancer cells

Anaplastic thyroid cancer (ATC) is among the most aggressive types of malignant cancer. Epidermal growth factor (EGF) plays a crucial role in the pathogenesis of ATC, and patients with thyroid carcinoma typically exhibit increased cysteine-rich protein 61 (Cyr61). In this study, we found that EGF treatment induced cell migration, stress fiber formation, Cyr61 mRNA and protein expressions, and Cyr61 protein secretion in ATC cells. The recombinant Cyr61 protein significantly induced cell migration; however, inhibition of Cyr61 activity by a Cyr61-specific antibody abrogated EGF-induced cell migration. EGF treatment also affected epithelial-to-mesenchymal transition (EMT)-related marker protein expression, as evidenced by an increase in vimentin and a decrease in E-cadherin expression. Inhibition of Cyr61 expression by Cyr61 siRNA decreased cell migration and reversed the EMT-related marker protein expression. EGF treatment increased the phosphorylation of the extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB), and finally activated Cyr61 promoter plasmid activity. Our results suggest that Cyr61 is induced by EGF through the ERK/CREB signal pathway and that it plays a crucial role in the migration and invasion of ATC cells; moreover, Cyr61 might be a therapeutic target for metastatic ATC.

Combined treatment with troglitazone and lovastatin inhibited epidermal growth factor-induced migration through the downregulation of cysteine-rich protein 61 in human anaplastic thyroid cancer cells

Our previous studies have demonstrated that epidermal growth factor (EGF) can induce cell migration through the induction of cysteine-rich protein 61 (Cyr61) in human anaplastic thyroid cancer (ATC) cells. The aim of the present study was to determine the inhibitory effects of combined treatment with the peroxisome proliferator-activated receptor-γ (PPARγ) ligand troglitazone and the cholesterol-lowering drug lovastatin at clinically achievable concentrations on ATC cell migration. Combined treatment with 5 μM troglitazone and 1 μM lovastatin exhibited no cytotoxicity but significantly inhibited EGF-induced migration, as determined using wound healing and Boyden chamber assays. Cotreatment with troglitazone and lovastatin altered the epithelial-to-mesenchymal-transition (EMT) -related marker gene expression of the cells; specifically, E-cadherin expression increased and vimentin expression decreased. In addition, cotreatment reduced the number of filopodia, which are believed to be involved in migration, and significantly inhibited EGF-induced Cyr61 mRNA and protein expression as well as Cyr61 secretion. Moreover, the phosphorylation levels of 2 crucial signal molecules for EGF-induced Cyr61 expression, the cAMP response element-binding protein (CREB) and extracellular signal-regulated kinase (ERK), were decreased in cells cotreated with troglitazone and lovastatin. Performing a transient transfection assay revealed that the combined treatment significantly suppressed Cyr61 promoter activity. These results suggest that combined treatment with low doses of troglitazone and lovastatin effectively inhibits ATC cell migration and may serve as a novel therapeutic strategy for metastatic ATC.

Laminin-5γ-2 (LAMC2) is highly expressed in anaplastic thyroid carcinoma and is associated with tumor progression, migration, and invasion by modulating signaling of EGFR

CONTEXT

Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy having no effective treatment. Laminin subunit-γ-2 (LAMC2) is an epithelial basement membrane protein involved in cell migration and tumor invasion and might represent an ideal target for the development of novel therapeutic approaches for ATC.

OBJECTIVE

The objective of the investigation was to study the role of LAMC2 in ATC tumorigenesis.

DESIGN

LAMC2 expression was evaluated by RT-PCR, Western blotting, and immunohistochemistry in tumor specimens, adjacent noncancerous tissues, and cell lines. The short hairpin RNA (shRNA) approach was used to investigate the effect of LAMC2 knockdown on the tumorigenesis of ATC.

RESULTS

LAMC2 was highly expressed in ATC samples and cell lines compared with normal thyroid tissues. Silencing LAMC2 by shRNA in ATC cells moderately inhibited cell growth in liquid culture and dramatically decreased growth in soft agar and in xenografts growing in immunodeficient mice. Silencing LAMC2 caused cell cycle arrest and significantly suppressed the migration, invasion, and wound healing of ATC cells. Rescue experiments by overexpressing LAMC2 in LAMC2 knockdown cells reversed the inhibitory effects as shown by increased cell proliferation and colony formation. Microarray data demonstrated that LAMC2 shRNA significantly altered the expression of genes associated with migration, invasion, proliferation, and survival. Immunoprecipitation studies showed that LAMC2 bound to epidermal growth factor receptor (EGFR) in the ATC cells. Silencing LAMC2 partially blocked epidermal growth factor-mediated activation of EGFR and its downstream pathway. Interestingly, cetuximab (an EGFR blocking antibody) or EGFR small interfering RNA additively enhanced the antiproliferative activity of the LAMC2 knockdown ATC cells compared with the control cells.

CONCLUSIONS

To our knowledge, this is the first report investigating the effect of LAMC2 on cell growth, cell cycle, migration, invasion, and EGFR signaling in ATC cells, suggesting that LAMC2 may be a potential therapeutic target for the treatment of ATC.

Orthotopic mouse models for the preclinical and translational study of targeted therapies against metastatic human thyroid carcinoma with BRAF(V600E) or wild-type BRAF

Molecular signature of advanced and metastatic thyroid carcinoma involves deregulation of multiple fundamental pathways activated in the tumor microenvironment. They include BRAF(V600E) and AKT that affect tumor initiation, progression and metastasis. Human thyroid cancer orthotopic mouse models are based on human cell lines that generally harbor genetic alterations found in human thyroid cancers. They can reproduce in vivo and in situ (into the thyroid) many features of aggressive and refractory human advanced thyroid carcinomas, including local invasion and metastasis. Humanized orthotopic mouse models seem to be ideal and commonly used for preclinical and translational studies of compounds and therapies not only because they may mimic key aspects of human diseases (e.g. metastasis), but also for their reproducibility. In addition, they might provide the possibility to evaluate systemic effects of treatments. So far, human thyroid cancer in vivo models were mainly used to test single compounds, non selective and selective. Despite the greater antitumor activity and lower toxicity obtained with different selective drugs in respect to non-selective ones, most of them are only able to delay disease progression, which ultimately could restart with similar aggressive behavior. Aggressive thyroid tumors (for example, anaplastic or poorly differentiated thyroid carcinoma) carry several complex genetic alterations that are likely cooperating to promote disease progression and might confer resistance to single-compound approaches. Orthotopic models of human thyroid cancer also hold the potential to be good models for testing novel combinatorial therapies. In this article, we will summarize results on preclinical testing of selective and nonselective single compounds in orthotopic mouse models based on validated human thyroid cancer cell lines harboring the BRAF(V600E) mutation or with wild-type BRAF. Furthermore, we will discuss the potential use of this model also for combinatorial approaches, which are expected to take place in the upcoming human thyroid cancer basic and clinical research.

Approach to the patient with anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma is the least common but most lethal of thyroid cancers. All patients are classified as stage IV, with the primary lesion restricted to the thyroid gland in stage IVA; locoregional lymph nodes may exist in IVA/IVB; and IVC disease is defined by distant metastases. Prognosis is highly dependent on disease extent at presentation, and staging and establishing a plan of care must be accomplished quickly. Although almost all studies are biased due to their retrospective nature, the most important factors associated with longer survival are completeness of surgical resection (achievable in only a minority of patients) and high-dose (>40 Gy) external beam radiotherapy (preferably intensity modulated radiation therapy). Recent reports suggest that a multimodal approach (surgery, radiation, and chemotherapy) is beneficial. Given the high lethality even with apparent local disease, combination systemic therapy (cytotoxics and/or targeted agents) may improve outcomes in stage IVA/IVB patients. Newer, more effective drug combinations are urgently needed for IVC patients who want aggressive therapy. A candid discussion of the prognosis and management options, including palliative care/hospice, should be held with the patient and caregiver as soon as possible after diagnosis to clarify the patient's preference and expectations. Prospective multicenter clinical trials, incorporating molecular analyses of tumors, are required if we are to improve survival in anaplastic thyroid carcinoma.

A comparative study of cell cycle mediator protein expression patterns in anaplastic and papillary thyroid carcinoma

Anaplastic thyroid carcinoma (ATC) is an extremely aggressive and rapidly fatal neoplasm. The aim of this study was to identify a limited cell cycle associated protein expression pattern unique to ATC and to correlate that pattern with clinical outcome. This represents one of the largest tissue micro-array projects comparing the cell cycle protein expression data of ATC to other well-differentiated tumors in the literature. Tissue microarrays were created from 21 patients with ATC and an age and gender matched cohort of patients with papillary thyroid carcinoma (PTC). Expression of epidermal growth factor receptor, cyclin D1, cyclin E, p53, p21, p16, aurora kinase A, opioid growth factor (OGF), OGF-receptor, thyroglobulin and Ki-67 was evaluated in a semi-quantitative fashion. Differences in protein expression between the cohorts were evaluated using chi-square tests with Bonferroni adjustments. Survival time and presence of metastasis at presentation were collected. The ATC cohort showed a statistically significant decrease (p < 0.05) in thyroglobulin expression and statistically significant increases (p < 0.05) in Ki-67 and p53 expression as compared with the PTC cohort. A trend toward loss of p16 and p21 expression was noted in the ATC cohort. A trend toward decreased survival was noted with p21 expression. These data indicate disruption of the normal cell cycle with aberrant expression of multiple protein markers suggesting increased proliferative activity and loss of control of cell cycle progression to G₁ phase. These findings support the assertion that ATC may represent the furthest end of a continuum of thyroid carcinoma dedifferentiation.

Epidermal growth factor receptor 1 expression is upregulated in undifferentiated thyroid carcinomas in humans

BACKGROUND

Epidermal growth factor receptor 1 (EGFR1) signaling is involved in human cancer cell progression and is responsible for aggressive biological behavior and poor clinical outcome in several human malignancies. Activation of the EGFR1 pathway has been proposed, among others, as being involved in the progression of thyroid cancer toward a thyroid-stimulating hormone (TSH)-independent phenotype. We have previously observed that undifferentiated thyroid carcinoma cells are hyper-sensitive to EGF signaling of downstream intracellular pathways, and this correlated both with the loss of TSH-dependency and increase in EGF-dependent proliferation and migration. Thus, we hypothesized that the upregulation of EGFR1 protein expression may be enhanced in parallel with transition toward a poorly differentiated phenotype in human thyroid carcinomas.

METHODS

The expression of EGFR1 was evaluated, by immunohistochemistry, in a series of 49 human thyroid carcinomas at different degrees of tumor differentiation.

RESULTS

The expression of EGFR1 protein was significantly upregulated in poorly differentiated and anaplastic thyroid carcinomas, whereas it was absent or faint in normal thyroid gland tissue and in differentiated thyroid papillary carcinomas. Of note, selected thyroid tumors characterized by a mixed population of differentiated and undifferentiated tumor cells, likely progressing from well to poorly differentiated and anaplastic phenotypes, exhibited EGFR1-negative differentiated fields together with EGFR1-positive poorly differentiated and anaplastic areas.

CONCLUSIONS

Upregulation of EGFR1 expression may be a molecular marker of dedifferentiation in thyroid epithelial carcinomas, likely being responsible for the activation of EGF signaling observed in tumor cells and favoring progression toward an angiogenic, poorly differentiated, TSH-independent phenotype.

Emerging therapies for thyroid carcinoma

Thyroid carcinoma is the most commonly diagnosed endocrine malignancy. Its incidence is currently rising worldwide. The discovery of genetic mutations associated with the development of thyroid cancer, such as BRAF and RET, has lead to the development of new drugs which target the pathways which they influence. Despite recent advances, the prognosis of anaplastic thyroid carcinoma is still unfavourable. In this review we look at emerging novel therapies for the treatment of well-differentiated and medullary thyroid carcinoma, and advances and future directions in the management of anaplastic thyroid carcinoma.

Targeted therapy of VEGFR2 and EGFR significantly inhibits growth of anaplastic thyroid cancer in an orthotopic murine model

PURPOSE

Anaplastic thyroid carcinoma (ATC) is one of the most lethal human cancers with a median survival of 6 months. The inhibition of epidermal growth factor receptor (EGFR) alone, or with VEGF receptor 2 (VEGFR2), represents an attractive approach for treatment of ATC. Several reports have examined agents that target these receptors. However, with the misidentification of as many as 60% of all commonly used ATC cell lines, the significance of these past findings is unclear.

EXPERIMENTAL DESIGN

Cell lines authenticated by short tandem repeat profiling were selected to establish xenograft tumors in an orthotopic murine model of ATC. These mice were then treated with vandetanib to evaluate its effects on ATC tumor growth. Dynamic contrast-enhanced (DCE) MRI was utilized to measure the impact of vandetanib on tumor vasculature.

RESULTS

Vandetanib inhibited tumor growth of the ATC cell lines Hth83 and 8505C in vivo by 69.3% (P < 0.001) and 66.6% (P < 0.05), respectively, when compared with control. Significant decreases in vascular permeability (P < 0.01) and vascular volume fraction (P < 0.05) were detected by DCE-MRI in the orthotopic xenograft tumors after 1 week of treatment with vandetanib as compared with control.

CONCLUSION

The inhibition of EGFR and VEGFR2 by vandetanib and its tremendous in vivo antitumor activity against ATC make it an attractive candidate for further preclinical and clinical development for the treatment of this particularly virulent cancer, which remains effectively untreatable. Vandetanib disrupts angiogenesis and DCE-MRI is an effective method to quantify changes in vascular function in vivo.

[Usefulness of the immunohistochemical analysis of several molecular markers in the characterization of papillary thyroid carcinoma with initial lymph node metastasis]

INTRODUCTION AND OBJECTIVE

Regional lymph node metastases (LNM) are a common finding in papillary thyroid cancer (PTC). Approximately half of patients have LNM at diagnosis. The aim of this study was to analyze immunohistochemically the combined expression of different PTC-related molecules in order to identify cases with a tendency to show LNM.

PATIENTS AND METHODS

Thirty-five patients were included in the study. The patients were distributed in two groups. Group I included 19 patients with no histological evidence of LNM at diagnosis. Group II included 16 patients with histological evidence of cervical LNM. Samples were stained for RET/PTC, EGFR, p16(INk4a), p21(cip1), p27(kip1), BCL2, and pAKT.

RESULTS

Expression of p21(cip1), p27(kip1), p16(INk4a), Bcl-2, and pAKT showed no differences between the two groups. However, RET/PTC and EGFR expression showed significant differences: in both cases, staining was more frequent in patients with LNM. Simultaneous positivity of RET/PTC and EGFR was a discriminative marker in patients with LNM. Finally, the combination of RET/PTC negative, EGFR negative and p16(INk4a) negative was found in none of the patients with LNM but in nearly half of those in group I.

CONCLUSIONS

Immunohistochemical analysis of several molecular markers could be useful in the phenotypic characterization of PTC. Application of these markers could enhance diagnosis and improve the management of patients with thyroid cancer.

Targeting epidermal growth factor receptor 1 signaling in human thyroid-stimulating hormone-independent thyroid carcinoma FRO cells results in a more chemosensitive and less angiogenic phenotype

BACKGROUND

Poorly differentiated and anaplastic thyroid cancers are aggressive malignancies unresponsive to standard treatments. The mechanisms responsible for the progression of thyroid tumors toward a thyroid-stimulating hormone (TSH)-independent phenotype are still under discussion, and a better understanding of them may provide novel molecular targets for the treatment of this disease. We evaluated the hypothesis that epithelial growth factor (EGF) signaling may play a role in favoring the loss of TSH dependency in human differentiated thyroid tumor cells.

METHODS

The sensitivity to EGF stimulation was evaluated in follicular thyroid carcinoma WRO cells that retain some features of thyroid cell differentiation and in undifferentiated TSH-independent thyroid carcinoma FRO cells.

RESULTS

It was observed that, while both cell lines are characterized by a similar EGF-dependent activation of the RAS/MAPK signaling pathway, only FRO cells exhibited a significant induction of phosphoAKT, cell proliferation, and migration as well as the up-regulation of vascular endothelial growth factor-A expression in response to EGF. On the other hand, the inhibition of epidermal growth factor receptor 1 signaling by its tyrosine kinase inhibitor, erlotinib, caused a selective down-regulation of FRO cell proliferation and induced a phenotype more sensitive to the proapoptotic activity of anthracyclins and taxoids. By contrast, the protracted stimulation of TSH-dependent WRO cells with EGF induced the loss of TSH dependency and the rearrangement of F-actin cytoskeleton.

CONCLUSIONS

These results suggest that the acquired sensitivity to EGF in these thyroid tumor cells may be responsible for the loss of differentiation in the transition toward a TSH-independent, invasive, and chemoresistant phenotype.

Anaplastic thyroid cancer: molecular pathogenesis and emerging therapies

Anaplastic thyroid cancer (ATC) is a rare malignancy. While external beam radiation therapy has improved locoregional control, the median survival of approximately 4 months has not changed in more than half a century due to uncontrolled systemic metastases. The objective of this study was to review the literature in order to identify potential new strategies for treating this highly lethal cancer. PubMed searches were the principal source of articles reviewed. The molecular pathogenesis of ATC includes mutations in BRAF, RAS, catenin (cadherin-associated protein), beta 1, PIK3CA, TP53, AXIN1, PTEN, and APC genes, and chromosomal abnormalities are common. Several microarray studies have identified genes and pathways preferentially affected, and dysregulated microRNA profiles differ from differentiated thyroid cancers. Numerous proteins involving transcription factors, signaling pathways, mitosis, proliferation, cell cycle, apoptosis, adhesion, migration, epigenetics, and protein degradation are affected. A variety of agents have been successful in controlling ATC cell growth both in vitro and in nude mice xenografts. While many of these new compounds are in cancer clinical trials, there are few studies being conducted in ATC. With the recent increased knowledge of the many critical genes and proteins affected in ATC, and the extensive array of targeted therapies being developed for cancer patients, there are new opportunities to design clinical trials based upon tumor molecular profiling and preclinical studies of potentially synergistic combinatorial novel therapies.

Postoperative management of thyroid carcinoma

Survival from differentiated thyroid carcinoma is generally good, but postoperative management plays an important role in minimizing the likelihood of disease recurrence. Postoperative management is generally performed by endocrinologists and nuclear medicine physicians, who exploit thyroid cells' inherent iodineavidity and sensitivity to hormonal manipulation in a unique cancer management paradigm. Endocrinologists manage thyroid hormone replacement/thyroid stimulating hormone suppression and coordinate surveillance. Nuclear physicians administer targeted therapy with radioactive iodine and perform imaging studies to assess disease status. This article provides an overview of the postoperative assessment, treatment, and follow-up of patients who have thyroid carcinoma.

Growth factor receptors expression in anaplastic thyroid carcinoma: potential markers for therapeutic stratification

Anaplastic thyroid carcinoma is a rare and universally fatal disease. Therefore, novel biomarkers are needed as surrogate end points in triaging patients for novel and selective biologic treatments. Up-regulation of several growth factor receptors has been shown to be associated with the biologic progression and response to targeted therapy of several malignancies. To determine the role of growth factor receptors in the biologic stratification of anaplastic thyroid carcinoma, we studied the expression of epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor beta, and HER-2 receptor in a large cohort of anaplastic thyroid carcinomas by immunohistochemical techniques. The percentage of positive cells, staining intensity and localization of staining in the anaplastic component, and coexisting well-differentiated thyroid carcinoma and adjacent nonneoplastic thyroid were evaluated for these markers. EGFR, platelet-derived growth factor receptor beta, and HER-2 were overexpressed in 58%, 16%, and 16% of anaplastic carcinomas, respectively. In tumors with adjacent normal thyroid parenchyma and/or differentiated carcinoma components, overexpression of all 3 markers was noted exclusively in the anaplastic component. Mutational analysis of exons 18, 19, and 21 of the EGFR gene showed no mutations in all anaplastic carcinomas. We conclude that the expression of these markers (1) may play a role in a subset of thyroid tumorigenesis and anaplastic transformation and (2) can be validated for potential use in the stratification of patients for targeted therapy.

Anaplastic Thyroid Carcinoma: Expression Profile of Targets for Therapy Offers New Insights for Disease Treatment

BACKGROUND

Anaplastic thyroid cancer is an endocrine malignancy. Its rare and rapidly lethal disease course has made it challenging to study. Little is known regarding the expression by anaplastic tumors of molecular targets for new human anticancer agents that have been studied in the preclinical or clinical setting. The objective of this work was to evaluate the expression profile of anaplastic thyroid tumors for molecular targets for treatment.

METHODS

Of the 94 cases of anaplastic thyroid cancers diagnosed and treated in British Columbia, Canada over a 20-year period (1984-2004), 32 cases (34%) had adequate archival tissue available for evaluation. A tissue microarray was constructed from these anaplastic thyroid tumors and immunohistochemistry was utilized to evaluate expression of 31 molecular markers. The markers evaluated were: epidermal growth factor receptor (EGFR), HER2, HER3, HER4, ER, PR, uPA-R, clusterin, E-cadherin, beta-catenin, AMF-R, c-kit, VEGF, ILK, aurora A, aurora B, aurora C, RET, CA-IX, IGF1-R, p53, MDM2, p21, Bcl-2, cyclin D1, cyclin E, p27, calcitonin, MIB-1, TTF-1, and thyroglobulin.

RESULTS

A single tumor with strong calcitonin expression was identified as a poorly differentiated medullary carcinoma and excluded from the study cohort. The mean age of the anaplastic cohort was 66 years; 16 patients (51%) were females, and the median patient survival was 23 weeks. A wide range in molecular marker expression was observed by the anaplastic thyroid cancer tumors (0-100%). The therapeutic targets most frequently and most strongly overexpressed by the anaplastic tumors were: beta-catenin (41%), aurora A (41%), cyclin E (67%), cyclin D1 (77%), and EGFR (84%).

CONCLUSIONS

Anaplastic thyroid tumors exhibit considerable derangement of their cell cycle and multiple signal transduction pathways that leads to uncontrolled cellular proliferation and the development of genomic instability. This report is the first to comprehensively evaluate a panel of molecular targets for therapy of anaplastic thyroid cancer and supports the development of clinical trials with agents such as cetuximab, small-molecule tyrosine kinase inhibitors, and aurora kinase inhibitors, which may offer new hope for individuals diagnosed with this fatal thyroid malignancy.

Epidermal growth factor receptor status in anaplastic thyroid carcinoma

BACKGROUND

The epidermal growth factor receptor (EGFR) has been reported to be overexpressed in anaplastic thyroid carcinoma (ATC). In vitro studies have shown that EGFR tyrosine kinase inhibitors (TKIs) greatly inhibit cellular growth and induced apoptosis in the ATC cell lines, while somatic mutations in the tyrosine kinase domain or an increased gene copy number are associated with increased sensitivity to TKIs in non-small cell lung cancer.

AIM

To investigate the prevalence of EGFR overexpression, gene amplification and activating mutation in the tyrosine kinase domain in patients with ATC.

METHODS

The EGFR gene status and protein expression were investigated by direct DNA sequencing of the hot-spot regions in exons 18, 19 and 21, fluorescence in situ hybridisation (FISH), and immunohistochemistry in tumour tissues from 23 patients with ATC.

RESULTS

On mutational analysis and FISH, neither mutations in the hot-spots nor gene amplification was observed. However, high polysomy was identified in 14/23 (60.9%) patients with ATC. All cases with immunohistochemistry (IHC) positivity (n = 6) had high polysomy, whereas 8/17 (47.1%) cases with IHC negativity had high polysomy (p = 0.048). High polysomy was observed in all 10 cases with giant cell subtype, but in only 4/11 (36.3%) with squamoid and 0/2 with spindle cell sarcomatoid subtype. There was no statistically significant correlation between FISH positivity of ATC tumour and presence of well-differentiated component.

CONCLUSION

Despite the low incidence of somatic EGFR gene mutation and amplification in the study samples, in view of the fact that high polysomy was often identified by FISH, as well as the current lack of therapeutic options, EGFR TKIs are worth investigating for treating the patients with ATC who have at least giant cell subtype.

New molecular targeted therapies in thyroid cancer

Carcinoma of the thyroid gland is the most common malignancy of the endocrine system. Differentiated tumors are often curable with surgical resection and radioactive iodine. A small percentage of such patients, however, do not undergo remission and need new therapeutic approaches. Both anaplastic and medullary thyroid carcinomas exhibit aggressive behavior and are usually resistant to current therapeutic modalities. Thyroid carcinoma represents a fascinating model and a particularly promising paradigm for targeted therapy because some of the key oncogenic events are activating mutations of genes coding for tyrosine kinases, and these occur early in cancer development. A prototype is the RET proto-oncogene, a receptor tyrosine kinase, which is a key regulator of development and a 'hotspot' for oncogenic mutations. Mutations in the RET proto-oncogene have been identified as causative for papillary carcinoma and familial medullary thyroid carcinoma, making it an attractive target for selective inhibition in these subtypes. ZD 6474 has shown promising activity in preclinical models against RET kinase, and its contemporary inhibition of vascular endothelial growth factor and epidermal growth factor pathways renders it a very attractive drug for clinical trials in thyroid cancer. Activating point mutation of B-RAF can occur early in the development of papillary carcinoma. Moreover, papillary carcinomas with these mutations have more aggressive properties and are diagnosed more often at an advanced stage. Clinical evaluation of B-RAF-targeting drugs is undergoing and trials in thyroid cancer are planned. Agents that restore radioiodine uptake, such as histone deacetylase inhibitors and retinoids, represent another exciting field in new drug development in thyroid cancer.

Cetuximab and irinotecan interact synergistically to inhibit the growth of orthotopic anaplastic thyroid carcinoma xenografts in nude mice

PURPOSE

Anaplastic thyroid carcinoma (ATC) remains one of the most lethal known human cancers. Targeted molecular therapy with cetuximab, a monoclonal antibody against epidermal growth factor receptor, offers new treatment potentials for patient with ATC. Cetuximab has also been reported to have synergistic effects when combined with irinotecan, a topoisomerase inhibitor. Therefore, we hypothesized that cetuximab and irinotecan would be effective in inhibiting the growth and progression of ATC in a murine orthotopic model.

EXPERIMENTAL DESIGN

The in vitro antiproliferative effects of cetuximab and irinotecan on ATC cell line ARO were examined. We also studied the in vivo effects of cetuximab and irinotecan on the growth, invasion, and metastasis of orthotopic ATC tumors in nude mice. The in vivo antitumor efficacy of cetuximab/irinotecan combination was also compared with that of doxorubicin.

RESULTS

Cetuximab alone did not show any antiproliferative or proapoptotic effect on this cell line. However, when combined with irinotecan, cetuximab potentiated the in vitro antiproliferative and proapoptotic effect of irinotecan. Cetuximab, irinotecan, and cetuximab/irinotecan combination resulted in 77%, 79%, and 93% in vivo inhibition of tumor growth, respectively. Incidences of lymph node metastasis, laryngeal invasion, and tumor microvessel density were also significantly decreased in these treatment groups. Furthermore, the cetuximab/irinotecan combination was significantly more effective than doxorubicin in inhibiting the growth of orthotopic ATC xenografts.

CONCLUSIONS

Combination therapy with cetuximab/irinotecan inhibits the growth and progression of orthotopic ATC xenografts in nude mice. Given the lack of curative options for patients with ATC, combination therapy with cetuximab and irinotecan treatment warrants further study.

Expression of KIT, EGFR, HER-2 and tyrosine phosphorylation in undifferentiated thyroid carcinoma: Implication for a new therapeutic approach

The KIT, epidermal growth factor receptor (EGFR) and HER-2 oncoproteins have tyrosine kinase activity and are molecular targets in human cancer therapy. To clarify the significance of KIT, EGFR, and HER-2 in undifferentiated thyroid carcinoma (UTC), the expression of these receptors and tyrosine phosphorylation was examined immunohistochemically in resected cases of UTC and papillary thyroid carcinoma (PTC). KIT, EGFR, and HER-2 were also examined at the protein and mRNA levels in five UTC cell lines. KIT expression (1+), EGFR overexpression (2+/3+), HER-2 expression (1+), and tyrosine phosphorylation were detected immunohistochemically in 40%, 70%, 10%, and 50% of the 10 UTC. In 20 PTC, KIT, EGFR, and HER-2 were not detected, but tyrosine phosphorylation was detected in 25% of cases. In the five UTC cell lines, KIT expression (1+), EGFR overexpression (3+), HER-2 expression (1+), and tyrosine phosphorylation were detected immunocytochemically in 60%, 100%, 20%, and 40%, respectively. Western blot analysis did not detect KIT expression, but did detect EGFR and HER-2 expression in all five cell lines. Real-time polymerase chain reaction detected KIT mRNA in two of the cell lines (40%), EGFR in five (100%), and HER-2 in three (60%). The present findings suggest that EGFR overexpression was involved in the proliferation and development of UTC and was frequently accompanied by tyrosine phosphorylation. Expression of KIT and HER-2 appeared to be weak but significant, suggesting a possible role in the development of UTC. Molecular therapies targeting KIT, EGFR, HER-2, and/or tyrosine phosphorylation might be indicated for UTC.