Immunohistochemical and sequencing analyses of the Wnt signaling components in Japanese anaplastic thyroid cancers

Anaplastic thyroid cancer: Genetic roles, targeted therapy, and immunotherapy

Anaplastic thyroid cancer (ATC) stands as the most formidable form of thyroid malignancy, presenting a persistent challenge in clinical management. Recent years have witnessed a gradual unveiling of the intricate genetic underpinnings governing ATC through next-generation sequencing. The emergence of this genetic landscape has paved the way for the exploration of targeted therapies and immunotherapies in clinical trials. Despite these strides, the precise mechanisms governing ATC pathogenesis and the identification of efficacious treatments demand further investigation. Our comprehensive review stems from an extensive literature search focusing on the genetic implications, notably the pivotal MAPK and PI3K-AKT-mTOR signaling pathways, along with targeted therapies and immunotherapies in ATC. Moreover, we screen and summarize the advances and challenges in the current diagnostic approaches for ATC, including the invasive tissue sampling represented by fine needle aspiration and core needle biopsy, immunohistochemistry, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography. We also investigate enormous studies on the prognosis of ATC and outline independent prognostic factors for future clinical assessment and therapy for ATC. By synthesizing this literature, we aim to encapsulate the evolving landscape of ATC oncology, potentially shedding light on novel pathogenic mechanisms and avenues for therapeutic exploration.

Tenascin-C Potentiates Wnt Signaling in Thyroid Cancer

Tenascin-C (TNC) is a secreted extracellular matrix protein that is highly expressed during embryonic development and re-expressed during wound healing, inflammation, and neoplasia. Studies in developmental models suggest that TNC may regulate the Wnt signaling pathway. Our laboratory has shown high levels of Wnt signaling and TNC expression in anaplastic thyroid cancer (ATC), a highly lethal cancer with an abysmal approximately 3- to 5-month median survival. Here, we investigated the role of TNC in facilitating ligand-dependent Wnt signaling in thyroid cancer. We used bulk RNA-sequencing from 3 independent multi-institutional thyroid cancer patient cohorts. TNC expression was spatially localized in patient tumors with RNA in situ hybridization. The role of TNC was investigated in vitro using Wnt reporter assays and in vivo with a NOD.PrkdcscidIl2rg-/- mouse ATC xenograft tumor model. TNC expression was associated with aggressive thyroid cancer behavior, including anaplastic histology, extrathyroidal extension, and metastasis. Spatial localization of TNC in patient tissue demonstrated a dramatic increase in expression within cancer cells along the invasive edge, adjacent to Wnt ligand-producing fibroblasts. TNC expression was also increased in areas of intravascular invasion. In vitro, TNC bound Wnt ligands and potentiated Wnt signaling. Finally, in an ATC mouse model, TNC increased Wnt signaling, tumor burden, invasion, and metastasis. Altogether, TNC potentiated ligand-driven Wnt signaling and promotes cancer cell invasion and metastasis in a mouse model of thyroid cancer. Understanding the role of TNC and its interaction with Wnt ligands could lead to the development of novel biomarkers and targeted therapeutics for thyroid cancer.

Tenascin-C potentiates Wnt signaling in thyroid cancer

Tenascin-C (TNC) is a secreted extracellular matrix protein that is highly expressed during embryonic development and re-expressed during wound healing, inflammation, and neoplasia. Studies in developmental models suggest that TNC may regulate the Wnt signaling pathway. Our lab has shown high levels of Wnt signaling and TNC expression in anaplastic thyroid cancer (ATC), a highly lethal cancer with an abysmal ~3-5 month median survival. Here, we investigated the role of TNC in facilitating ligand-dependent Wnt signaling in thyroid cancer. We utilized bulk RNA-sequencing from three independent multi-institutional thyroid cancer patient cohorts. TNC expression was spatially localized in patient tumors with RNA in situ hybridization. The role of TNC was investigated in vitro using Wnt reporter assays and in vivo with a NOD.PrkdcscidIl2rg-/- mouse ATC xenograft tumor model. TNC expression was associated with aggressive thyroid cancer behavior, including anaplastic histology, extrathyroidal extension, and metastasis. Spatial localization of TNC in patient tissue demonstrated a dramatic increase in expression within cancer cells along the invasive edge, adjacent to Wnt ligand-producing fibroblasts. TNC expression was also increased in areas of intravascular invasion. In vitro, TNC bound Wnt ligands and potentiated Wnt signaling. Finally, in an ATC mouse model, TNC increased Wnt signaling, tumor burden, invasion, and metastasis. Altogether, TNC potentiated ligand driven Wnt signaling and promotes cancer cell invasion and metastasis in a mouse model of thyroid cancer. Understanding the role of TNC and its interaction with Wnt ligands could lead to the development of novel biomarkers and targeted therapeutics for thyroid cancer.

Wnt/β-catenin signaling is a therapeutic target in anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC) is a highly aggressive malignancy that has consistently shown Wnt/β-catenin (canonical) signaling activation in various study populations. There are currently no targetable treatments for BRAF-wildtype ATC and a lack of effective treatment for BRAFV600EATC. Our aim is to identify whether Wnt inhibitors could be potential therapeutic agents for ATC patients with limited treatment options.

METHODS

In this Institutional Review Board-approved study, we utilize a cohort of 32 ATCs and 20 non-neoplastic multinodular goiters (MNG). We also use 4 ATC spheroid cell lines (THJ-16T, THJ-21T, THJ-29T, and THJ-11T) and two primary patient-derived ATC organoid cultures (VWL-T5 and VWL-T60). Finally, we use a murine xenograft mouse model of ATC for in vivo treatment studies.

RESULTS

Using a large patient cohort, we demonstrate that this near-universal Wnt signaling activation is associated with ligand expression- rather than being mutationally-driven. We show that pyrvinium pamoate, a potent Wnt inhibitor, exhibits in vitro efficacy against both ATC cell lines and primary patient-derived ATC organoids VWL-T5 (p < 0.05) and VWL-T60 (p < 0.01) Finally, using a murine xenograft model of ATC, we show that pyrvinium significantly delays the growth of ATC tumors in THJ-16T (p < 0.005) and THJ-21T (p < 0.001).

CONCLUSIONS

We tested Wnt inhibitor treatment, both in vitro and in vivo, as a potential novel therapy for this highly lethal disease. Future large-scale studies utilizing multiple Wnt inhibitors will lay the foundation for the development of these novel therapies for patients with ATC.

Identification of Germline FOXE1 and Somatic MAPK Pathway Gene Alterations in Patients with Malignant Struma Ovarii, Cleft Palate and Thyroid Cancer

Germline variants in the FOXE1 transcription factor have been associated with thyroid ectopy, cleft palate (CP) and thyroid cancer (TC). Here, we aimed to clarify the role of FOXE1 in Portuguese families (F1 and F2) with members diagnosed with malignant struma ovarii (MSO), an ovarian teratoma with ectopic malignant thyroid tissue, papillary TC (PTC) and CP. Two rare germline heterozygous variants in the FOXE1 promoter were identified: F1) c.-522G>C, in the proband (MSO) and her mother (asymptomatic); F2) c.9C>T, in the proband (PTC), her sister and her mother (CP). Functional studies using rat normal thyroid (PCCL3) and human PTC (TPC-1) cells revealed that c.9C>T decreased FOXE1 promoter transcriptional activity in both cell models, while c.-522G>C led to opposing activities in the two models, when compared to the wild type. Immunohistochemistry and RT-qPCR analyses of patients' thyroid tumours revealed lower FOXE1 expression compared to adjacent normal and hyperplastic thyroid tissues. The patient with MSO also harboured a novel germline AXIN1 variant, presenting a loss of heterozygosity in its benign and malignant teratoma tissues and observable β-catenin cytoplasmic accumulation. The sequencing of the F1 (MSO) and F2 (PTC) probands' tumours unveiled somatic BRAF and HRAS variants, respectively. Germline FOXE1 and AXIN1 variants might have a role in thyroid ectopy and cleft palate, which, together with MAPK pathway activation, may contribute to tumours' malignant transformation.

Association of AXIN1 rs12921862 C/A and rs1805105 G/A and CTSB rs12898 G/A polymorphisms with papillary thyroid carcinoma: A case-control study

BACKGROUND

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer which its precise etiology remains unknown. However, environmental and genetic factors contribute to the etiology of PTC. Axis inhibition protein 1 (Axin1) is a scaffold protein that exerts its role as a tumor suppressor. In addition, Cathepsin B (Ctsb) is a cysteine protease with higher expression in several types of tumors. Therefore, the aim of this study was to investigate the possible association of AXIN1 rs12921862 C/A and rs1805105 G/A and CTSB rs12898 G/A polymorphisms with PTC susceptibility.

MATERIALS & METHODS

In total, 156 PTC patients and 158 sex-, age-, and BMI-matched control subjects were enrolled in the study. AXIN1 rs12921862 C/A and rs1805105 G/A and CTSB rs12898 G/A polymorphisms were genotyped using the PCR-RFLP method.

RESULTS

There was a relationship between AXIN1 rs12921862 C/A polymorphism and an increased risk of PTC in all genetic models except the overdominant model. The AXIN1 rs1805105 G/A polymorphism was associated with an increased PTC risk only in codominant and overdominant models. The frequency of AXIN1 A_rs12921862 A_rs1805105 haplotype was higher in the PTC group and also this haplotype was associated with an increased risk of PTC. Moreover, the AXIN1 rs12921862 C/A polymorphism was not associated with PTC clinical and pathological findings, but AXIN1 rs1805105 G/A polymorphism was associated with almost three folds of larger tumor size (≥1 cm). There was no association between CTSB rs12898 G/A polymorphism and PTC and its findings.

CONCLUSION

The AXIN1 rs12921862 C/A and rs1805105 G/A polymorphisms were associated with PTC. AXIN1 rs1805105 G/A polymorphism was associated with higher tumor size.

Thyroid Cancer and COVID-19: Prospects for Therapeutic Approaches and Drug Development

Thyroid cancer is the most prevalent endocrine malignancy and the reported incidence of thyroid cancer has continued to increase in recent years. Since 2019, coronavirus disease 2019 (COVID-19) has been spreading worldwide in a global pandemic. COVID-19 aggravates primary illnesses and affects disease management; relevant changes include delayed diagnosis and treatment. The thyroid is an endocrine organ that is susceptible to autoimmune attack; thus, thyroid cancer after COVID-19 has gradually attracted attention. Whether COVID-19 affects the diagnosis and treatment of thyroid cancer has also attracted the attention of many researchers. This review examines the literature regarding the influence of COVID-19 on the pathogenesis, diagnosis, and treatment of thyroid cancer; it also focuses on drug therapies to promote research into strategies for improving therapy and management in thyroid cancer patients with COVID-19.

PRKAR1A and Thyroid Tumors

Simple Summary

In 2021 it is estimated that there will be 44,280 new cases of thyroid cancer in the United States and the incidence rate is higher in women than in men by almost 3 times. Well-differentiated thyroid cancer is the most common subtype of thyroid cancer and includes follicular (FTC) and papillary (PTC) carcinomas. Over the last decade, researchers have been able to better understand the molecular mechanisms involved in thyroid carcinogenesis, identifying genes including but not limited to RAS, BRAF, PAX8/PPARγ chromosomal rearrangements and others, as well as several tumor genes involved in major signaling pathways regulating cell cycle, differentiation, growth, or proliferation. Patients with Carney complex (CNC) have increased incidence of thyroid tumors, including cancer, yet little is known about this association. CNC is a familial multiple neoplasia and lentiginosis syndrome cause by inactivating mutations in the PRKAR1A gene which encodes the regulatory subunit type 1α of protein kinase A. This work summarizes what we know today about PRKAR1A defects in humans and mice and their role in thyroid tumor development, as the first such review on this issue.

Abstract

Thyroid cancer is the most common type of endocrine malignancy and the incidence is rapidly increasing. Follicular (FTC) and papillary thyroid (PTC) carcinomas comprise the well-differentiated subtype and they are the two most common thyroid carcinomas. Multiple molecular genetic and epigenetic alterations have been identified in various types of thyroid tumors over the years. Point mutations in BRAF, RAS as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements are common. Thyroid cancer, including both FTC and PTC, has been observed in patients with Carney Complex (CNC), a syndrome that is inherited in an autosomal dominant manner and predisposes to various tumors. CNC is caused by inactivating mutations in the tumor-suppressor gene encoding the cyclic AMP (cAMP)-dependent protein kinase A (PKA) type 1α regulatory subunit (PRKAR1A) mapped in chromosome 17 (17q22–24). Growth of the thyroid is driven by the TSH/cAMP/PKA signaling pathway and it has been shown in mouse models that PKA activation through genetic ablation of the regulatory subunit Prkar1a can cause FTC. In this review, we provide an overview of the molecular mechanisms contributing to thyroid tumorigenesis associated with inactivation of the RRKAR1A gene.

Molecular aberrations and signaling cascades implicated in the pathogenesis of anaplastic thyroid cancer

Anaplastic Thyroid Cancer (ATC) accounts for >40% thyroid cancer-related deaths and has a dismal prognosis. In the past decade, significant efforts have been made towards understanding the pathogenesis of this disease and developing novel therapeutics. Unfortunately, effective treatment is still lacking and a more thorough understanding of ATC pathogenesis may provide new opportunities to improve ATC therapeutics. This review provides insights into ATC clinical presentation and pathology, and the putative role of genetic aberrations and alterations in molecular signaling pathways in ATC pathogenesis. We reviewed prevalent mutations, chromosomal abnormalities and fusions, epigenetic alterations and dysregulations in ATC, and highlighted several signaling cascades which appeared to be integral to ATC pathogenesis. Moreover, these features offer insights into de-differentiated, aggressive and drug-resistant phenotype of ATC, and thus may help in exploring potential new molecular targets for developing novel therapeutics.

Identification of Key Pathways and Genes in Anaplastic Thyroid Carcinoma via Integrated Bioinformatics Analysis

BACKGROUND To provide a better understanding of anaplastic thyroid carcinoma (ATC) at the molecular level, this study aimed to identify the genes and key pathways associated with ATC by using integrated bioinformatics analysis. MATERIAL AND METHODS Based on the microarray data GSE9115, GSE65144, and GSE53072 derived from the Gene Expression Omnibus, the differentially expressed genes (DEGs) between ATC samples and normal controls were identified. With DEGs, we performed a series of functional enrichment analyses. Then, a protein-protein interaction (PPI) network was constructed and visualized, with which the hub gene nodes were screened out. Finally, modules analysis for the PPI network was performed to further investigate the potential relationships between DEGs and ATC. RESULTS A total of 537 common DEGs were screened out from all 3 datasets, among which 247 genes were upregulated and 275 genes were downregulated. GO analysis indicated that upregulated DEGs were mainly involved in cell division and mitotic nuclear division and the downregulated DEGs were significantly enriched in ventricular cardiac muscle cell action potential. KEGG pathway analysis showed that the upregulated DEGs were mainly enriched in cell cycle and ECM-receptor interaction and the downregulated DEGs were mainly enriched in thyroid hormone synthesis, insulin resistance, and pathways in cancer. The top 10 hub genes in the constructed PPI network were CDK1, CCNB1, TOP2A, AURKB, CCNA2, BUB1, AURKA, CDC20, MAD2L1, and BUB1B. The modules analysis showed that genes in the top 2 significant modules of PPI network were mainly associated with mitotic cell cycle and positive regulation of mitosis, respectively. CONCLUSIONS We identified a series of key genes along with the pathways that were most closely related with ATC initiation and progression. Our results provide a more detailed molecular mechanism for the development of ATC, shedding light on the potential biomarkers and therapeutic targets.

Wnt Signaling in Thyroid Homeostasis and Carcinogenesis

The Wnt pathway is essential for stem cell maintenance, but little is known about its role in thyroid hormone signaling and thyroid stem cell survival and maintenance. In addition, the role of Wnt signaling in thyroid cancer progenitor cells is also unclear. Here, we present emerging evidence for the role of Wnt signaling in somatic thyroid stem cell and thyroid cancer stem cell function. An improved understanding of the role of Wnt signaling in thyroid physiology and carcinogenesis is essential for improving both thyroid disease diagnostics and therapeutics.

Targeted next-generation sequencing of cancer genes in poorly differentiated thyroid cancer

Poorly differentiated thyroid carcinoma (PDTC) is a rare malignancy with higher mortality than well-differentiated thyroid carcinoma. The histological diagnosis can be difficult as well as the therapy. Improved diagnosis and new targeted therapies require knowledge of DNA sequence changes in cancer-relevant genes. The TruSeq Amplicon Cancer Panel was used to screen cancer genomes from 25 PDTC patients for somatic single-nucleotide variants in 48 genes known to represent mutational hotspots. A total of 4490 variants were found in 23 tissue samples of PDTC. Ninety-eight percent (4392) of these variants did not meet the inclusion criteria, while 98 potentially pathogenic or pathogenic variants remained after filtering. These variants were distributed over 33 genes and were all present in a heterozygous state. Five tissue samples harboured not a single variant. Predominantly, variants in P53 (43% of tissue samples) were identified, while less frequently, variants in APC, ERBB4, FLT3, KIT, SMAD4 and BRAF (each in 17% of tissue samples) as well as ATM, EGFR and FBXW7 (each in 13% of tissue samples) were observed. This study identified new potential genetic targets for further research in PDTC. Of particular interest are four observed ERBB4 (alias HER4) variants, which have not been connected to this type of thyroid carcinoma so far. In addition, APC and SMAD4 mutations have not been reported in this subtype of cancer either. In contrast to other reports, we did not find CTNNB1 variants.

cMYC expression in thyroid follicular cell-derived carcinomas: a role in thyroid tumorigenesis

BACKGROUND

cMYC regulates approximately 15% of human genes and is involved in up to 20% of all human cancers. Reports discussing cMYC protein expression in thyroid carcinomas are limited, with controversies pertaining to cMYC expression patterns noted in the literature. The aims of the current study were to clarify patterns and intensities of cMYC expression in follicular cell-derived thyroid carcinomas across a spectrum of cancer morphologies and disease aggressivities, to correlate cMYC with BRAF^V600E expression, and to evaluate the potential role of cMYC in progression of well-differentiated thyroid carcinomas into less well-differentiated carcinomas.

METHODS

Immunohistochemical studies using specific monoclonal antibodies for cMYC and BRAF^V600E were performed on tissue microarrays built from follicular cell-derived thyroid carcinomas (25 papillary, 24 follicular, 24 oncocytic variant of follicular, and 21 undifferentiated). In addition, cMYC IHC testing was also performed on whole tissue tumor sections from a subset of patients. Nodular hyperplasia cases were used as non-neoplastic controls. Appropriate positive and negative controls were included.

RESULTS

cMYC was expressed almost exclusively in a nuclear fashion in both thyroid carcinomas and nodular hyperplasias. cMYC expression was weakly positive in both nodular hyperplasias and well-differentiated carcinomas. The majority of undifferentiated carcinomas (UDCs) showed strong nuclear cMYC positivity. PTC cases that were positive for cMYC (6/25) harbored the BRAF ^V600E mutation. A correlation was confirmed between cMYC intensity and tumor size in UDCs. UDC cases that developed out of well-differentiated thyroid carcinomas showed frank overexpression of cMYC in the undifferentiated tumor components.

CONCLUSIONS

Our study suggests that nuclear overexpression of cMYC correlates with tumorigenesis / dedifferentiation in follicular cell derived thyroid carcinomas, a concept that has not been shown before on whole tissue sections.

Current Advances in Thyroid Cancer Management. Are We Ready for the Epidemic Rise of Diagnoses?

A rising incidence of thyroid cancers (TCs) mainly small tumors, observed during recent years, lead to many controversies regarding treatment strategies. TCs represent a distinct molecular background and clinical outcome. Although in most cases TCs are characterized by a good prognosis, there are some aggressive forms, which do not respond to standard treatment. There are still some questions, which have to be resolved to avoid dangerous simplifications in the clinical management. In this article, we focused on the current advantages in preoperative molecular diagnostic tests and histopathological examination including noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). We discussed the controversies regarding the extent of thyroid surgery and adjuvant radioiodine therapy, as well as new treatment modalities for radioiodine-refractory differentiated thyroid cancer (RR-DTC). Considering medullary thyroid cancer (MTC), we analyzed a clinical management based on histopathology and RET (ret proto-oncogene) mutation genotype, disease follow-up with a special attention to serum calcitonin doubling time as an important prognostic marker, and targeted therapy applied in advanced MTC. In addition, we provided some data regarding anaplastic thyroid cancer (ATC), a highly lethal neoplasm, which lead to death in nearly 100% of patients due to the lack of effective treatment options.

Activated E2F activity induces cell death in papillary thyroid carcinoma K1 cells with enhanced Wnt signaling

Disruption of Wnt signaling often happens in tumorigenesis, but whether Wnt signaling affects the early stages of thyroid tumor, such as papillary thyroid carcinoma, is still a question, especially in the papillary thyroid carcinoma without genomic RET/PTC mutation. In this study, we demonstrated the important function of Wnt signaling in papillary thyroid carcinoma K1 cells, which have no RET/PTC mutation. We found that K1 cells have enhanced Wnt signaling in comparison to normal thyroid cells. We further demonstrated that K1 cells require the enhanced Wnt signaling for growth and survival. Interestingly, we identified that enhancing E2F activity by either knockdown of Rb or overexpression of Cyclin D1 induces cell death in K1 cells. And we further revealed that the cell death is caused by enhanced oxidative stress. Our studies present a novel cell model to support the key roles of Wnt signaling in early stage of thyroid tumor, and also provide an alternative way to limit thyroid cancer.

Genomic Landscape of poorly Differentiated and Anaplastic Thyroid Carcinoma

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) are aggressive thyroid tumors associated with a high mortality rate of 38-57 % and almost 100 % respectively. Several recent studies utilizing next generation sequencing techniques have shed lights on the molecular pathogenesis of these tumors, providing evidence to support a stepwise tumoral progression from well-differentiated to poorly differentiated, and finally to anaplastic thyroid carcinomas. While BRAF (V600E) and RAS mutations remain the main drivers in aggressive thyroid carcinoma, PDTC and ATC gains additional mutations, e.g., TERT promoter mutation, TP53 mutation, as well as frequent alterations in PIK3CA-PTEN-AKT-mTOR pathway, SWI-SNF complex, histomethyltransferases, and mismatch repair genes. RAS-mutated PDTCs are commonly associated with a histologic phenotype defined by Turin proposal, high frequency of distant metastasis, high thyroid differentiation score, and a RAS-like gene expression profile, whereas BRAF-mutated PDTCs are usually defined solely by the Memorial Sloan Kettering Cancer Center (MSKCC) criteria with a propensity for nodal metastasis and are less differentiated with a BRAF-like expression signature. Such demarcation is largely lost in ATC which is characterized by genomic complexity, heavy mutation burden, and profound undifferentiation. Additionally, several molecular events, e.g., EIF1AX mutation, mutation burden, and chromosome 1q gain in PDTCs, as well as EIF1AX mutation, chromosome 13q loss, and 20q gains in ATCs, may serve as adverse prognostic markers predicting poor clinical outcome.

Sorafenib and Quinacrine Target Anti-Apoptotic Protein MCL1: A Poor Prognostic Marker in Anaplastic Thyroid Cancer (ATC)

PURPOSE AND EXPERIMENTAL DESIGN

Anaplastic thyroid cancer (ATC) comprises approximately 2% of all thyroid cancers, and its median survival rate remains poor. It is responsible for more than one third of thyroid cancer-related deaths. ATC is frequently resistant to conventional therapy, and NFκB signaling has been proposed to be a feature of the disease. We aimed to assess the activity of the antimalaria drug quinacrine known to target NFκB signaling in combination with the clinically relevant kinase inhibitor sorafenib in ATC cells. The presence of NFκB-p65/RELA and its target MCL1 was demonstrated in ATC by meta-data gene set enrichment analysis and IHC. We assessed the responses of a panel of human ATC cell lines to quinacrine and sorafenib in vitro and in vivo RESULTS: We detected increased expression of NFκB-p65/RELA and MCL1 in the nucleus of a subset of ATC compared with non-neoplastic thyroid. ATC cells were found to respond with additive/synergistic tumor cell killing to the combination of sorafenib plus quinacrine in vitro, and the drug combination improves survival of immunodeficient mice injected orthotopically with ATC cells as compared with mice administered either compound alone or doxorubicin. We also demonstrate that the combination of sorafenib and quinacrine is well tolerated in mice. At the molecular level, quinacrine and sorafenib inhibited expression of prosurvival MCL1, pSTAT3, and dampened NFκB signaling.

CONCLUSIONS

The combination of quinacrine and sorafenib targets emerging molecular hallmarks of ATC and shows promising results in clinically relevant models for the disease. Further testing of sorafenib plus quinacrine can be conducted in ATC patients. Clin Cancer Res; 22(24); 6192-203. ©2016 AACR.

Signaling Pathways in Thyroid Cancer and Their Therapeutic Implications

Thyroid cancer is a common malignancy of endocrine system, and has now become the fastest increasing cancer among all the malignancies. The development, progression, invasion, and metastasis are closely associated with multiple signaling pathways and the functions of related molecules, such as Src, Janus kinase (JAK)-signal transducers and activators of transcription (STAT), mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt, NF-κB, thyroid stimulating hormone receptor (TSHR), Wnt-β-catenin and Notch signaling pathways. Each of the signaling pathways could exert its function singly or through network with other pathways. These pathways could cooperate, promote, antagonize, or interact with each other to form a complex network for the regulation. Dysfunction of this network could increase the development, progression, invasion, and metastasis of thyroid cancer. Inoperable thyroid cancer still has a poor prognosis. However, signaling pathway-related targeted therapies offer the hope of longer quality of meaningful life for this small group of patients. Signaling pathway-related targets provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer. In the present work, the advances in these signaling pathways and targeted treatments of thyroid cancer were reviewed.

Genomic and transcriptomic hallmarks of poorly differentiated and anaplastic thyroid cancers

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) are rare and frequently lethal tumors that so far have not been subjected to comprehensive genetic characterization.

METHODS

We performed next-generation sequencing of 341 cancer genes from 117 patient-derived PDTCs and ATCs and analyzed the transcriptome of a representative subset of 37 tumors. Results were analyzed in the context of The Cancer Genome Atlas study (TCGA study) of papillary thyroid cancers (PTC).

RESULTS

Compared to PDTCs, ATCs had a greater mutation burden, including a higher frequency of mutations in TP53, TERT promoter, PI3K/AKT/mTOR pathway effectors, SWI/SNF subunits, and histone methyltransferases. BRAF and RAS were the predominant drivers and dictated distinct tropism for nodal versus distant metastases in PDTC. RAS and BRAF sharply distinguished between PDTCs defined by the Turin (PDTC-Turin) versus MSKCC (PDTC-MSK) criteria, respectively. Mutations of EIF1AX, a component of the translational preinitiation complex, were markedly enriched in PDTCs and ATCs and had a striking pattern of co-occurrence with RAS mutations. While TERT promoter mutations were rare and subclonal in PTCs, they were clonal and highly prevalent in advanced cancers. Application of the TCGA-derived BRAF-RAS score (a measure of MAPK transcriptional output) revealed a preserved relationship with BRAF/RAS mutation in PDTCs, whereas ATCs were BRAF-like irrespective of driver mutation.

CONCLUSIONS

These data support a model of tumorigenesis whereby PDTCs and ATCs arise from well-differentiated tumors through the accumulation of key additional genetic abnormalities, many of which have prognostic and possible therapeutic relevance. The widespread genomic disruptions in ATC compared with PDTC underscore their greater virulence and higher mortality.

FUNDING

This work was supported in part by NIH grants CA50706, CA72597, P50-CA72012, P30-CA008748, and 5T32-CA160001; the Lefkovsky Family Foundation; the Society of Memorial Sloan Kettering; the Byrne fund; and Cycle for Survival.

Synergistic signaling of KRAS and thyroid hormone receptor β mutants promotes undifferentiated thyroid cancer through MYC up-regulation

Undifferentiated thyroid carcinoma is one of the most aggressive human cancers with frequent RAS mutations. How mutations of the RAS gene contribute to undifferentiated thyroid cancer remains largely unknown. Mice harboring a potent dominant negative mutant thyroid hormone receptor β, TRβPV (Thrb(PV/PV)), spontaneously develop well-differentiated follicular thyroid cancer similar to human cancer. We genetically targeted the Kras(G12D) mutation to thyroid epithelial cells of Thrb(PV/PV) mice to understand how Kras(G12D) mutation could induce undifferentiated thyroid cancer in Thrb(PV/PV)Kras(G12D) mice. Thrb(PV/PV)Kras(G12D) mice exhibited poorer survival due to more aggressive thyroid tumors with capsular invasion, vascular invasion, and distant metastases to the lung occurring at an earlier age and at a higher frequency than Thrb(PV/PV) mice did. Importantly, Thrb(PV/PV)Kras(G12D) mice developed frequent anaplastic foci with complete loss of normal thyroid follicular morphology. Within the anaplastic foci, the thyroid-specific transcription factor paired box gene 8 (PAX8) expression was virtually lost and the loss of PAX8 expression was inversely correlated with elevated MYC expression. Consistently, co-expression of KRAS(G12D) with TRβPV upregulated MYC levels in rat thyroid pccl3 cells, and MYC acted to enhance the TRβPV-mediated repression of the Pax8 promoter activity of a distant upstream enhancer, critical for thyroid-specific Pax8 expression. Our findings indicated that synergistic signaling of KRAS(G12D) and TRβPV led to increased MYC expression. Upregulated MYC contributes to the initiation of undifferentiated thyroid cancer, in part, through enhancing TRβPV-mediated repression of the Pax8 expression. Thus, MYC might serve as a potential target for therapeutic intervention.

Characterization of the mutational landscape of anaplastic thyroid cancer via whole-exome sequencing

Anaplastic thyroid carcinoma (ATC) is a frequently lethal malignancy that is often unresponsive to available therapeutic strategies. The tumorigenesis of ATC and its relationship to the widely prevalent well-differentiated thyroid carcinomas are unclear. We have analyzed 22 cases of ATC as well as 4 established ATC cell lines using whole-exome sequencing. A total of 2674 somatic mutations (121/sample) were detected. Ontology analysis revealed that the majority of variants aggregated in the MAPK, ErbB and RAS signaling pathways. Mutations in genes related to malignancy not previously associated with thyroid tumorigenesis were observed, including mTOR, NF1, NF2, MLH1, MLH3, MSH5, MSH6, ERBB2, EIF1AX and USH2A; some of which were recurrent and were investigated in 24 additional ATC cases and 8 ATC cell lines. Somatic mutations in established thyroid cancer genes were detected in 14 of 22 (64%) tumors and included recurrent mutations in BRAF, TP53 and RAS-family genes (6 cases each), as well as PIK3CA (2 cases) and single cases of CDKN1B, CDKN2C, CTNNB1 and RET mutations. BRAF V600E and RAS mutations were mutually exclusive; all ATC cell lines exhibited a combination of mutations in either BRAF and TP53 or NRAS and TP53. A hypermutator phenotype in two cases with >8 times higher mutational burden than the remaining mean was identified; both cases harbored unique somatic mutations in MLH mismatch-repair genes. This first comprehensive exome-wide analysis of the mutational landscape of ATC identifies novel genes potentially associated with ATC tumorigenesis, some of which may be targets for future therapeutic intervention.

Pax-8-PPAR-γ fusion protein in thyroid carcinoma

Thyroid carcinoma is the most common endocrine malignancy, and its incidence is continuing to increase. Most thyroid carcinomas contain one of several known driver mutations, such as the Val600Glu substitution in B-Raf, Ras mutations, RET gene fusions, or PAX8-PPARG gene fusions. The PAX8-PPARG gene fusion results in the production of a Pax-8-PPAR-γ fusion protein (PPFP), which is found in approximately one-third of follicular thyroid carcinomas, as well as some follicular-variant papillary thyroid carcinomas. In vitro and in vivo evidence indicates that PPFP is an oncoprotein. Although specific mechanisms of action remain to be defined, PPFP is considered to act as a dominant-negative inhibitor of wild-type PPAR-γ and/or as a unique transcriptional activator of subsets of PPAR-γ-responsive and Pax-8-responsive genes. Detection of the fusion transcript in thyroid nodule biopsy specimens can aid clinical decision-making when cytological findings are indeterminate. The PPAR-γ agonist pioglitazone is highly therapeutic in a transgenic mouse model of PPFP-positive thyroid carcinoma, suggesting that PPAR-γ agonists might be beneficial in patients with PPFP-positive thyroid carcinomas.

Cell cycle deregulation and TP53 and RAS mutations are major events in poorly differentiated and undifferentiated thyroid carcinomas

BACKGROUND

Anaplastic thyroid carcinomas (ATCs) are among the most lethal malignancies, for which there is no effective treatment.

OBJECTIVE

In the present study, we aimed to elucidate the molecular alterations contributing to ATC development and to identify novel therapeutic targets.

DESIGN

We profiled the global gene expression of five ATCs and validated differentially expressed genes by quantitative RT-PCR in an independent set of tumors. In a series of 26 ATCs, we searched for pathogenic alterations in genes involved in the most deregulated cellular processes, including the hot spot regions of RAS, BRAF, TP53, CTNNB1 (β-catenin), and PIK3CA genes, and, for the first time, a comprehensive analysis of components involved in the cell cycle [cyclin-dependent kinase (CDK) inhibitors (CDKI): CDKN1A (p21(CIP1)); CDKN1B (p27(KIP1)); CDKN2A (p14(ARF), p16(INK4A)); CDKN2B (p15(INK4B)); CDKN2C (p18(INK4C))], cell adhesion (AXIN1), and proliferation (PTEN). Mutational analysis was also performed in 22 poorly differentiated thyroid carcinomas (PDTCs).

RESULTS

Expression profiling revealed that ATCs were characterized by the underexpression of epithelial components and the up regulation of mesenchymal markers and genes from TGF-β pathway, as well as, the overexpression of cell cycle-related genes. In accordance, the up regulation of the SNAI2 gene, a TGF-β-responsive mesenchymal factor, was validated. CDKN3, which prevents the G1/S transition, was significantly up regulated in ATCs and PDTCs and aberrantly spliced in ATCs. Mutational analysis showed that most mutations were present in TP53 (42% of ATCs; 27% of PDTCs) or RAS (31% of ATCs; 18% of PDTCs). TP53 and RAS alterations showed evidence of mutual exclusivity (P = .0354). PIK3CA, PTEN, and CDKI mutations were present in 14%-20% of PDTCs, and in 10%-14% of ATCs. BRAF, CTNNB1, and AXIN1 mutations were rarely detected.

CONCLUSION

Overall, this study identified crucial roles for TP53, RAS, CDKI, and TGF-β pathway, which may represent feasible therapeutic targets for ATC and PDTC treatment.

Recent progress of genome study for anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) belongs to the most malignant and rapidly progressive human thyroid cancers and its prognosis is very poor. Also, it shows high resistance to cancer treatments, so that effective treatment for ATC has not been found to date, and virtually all patients terminate their life rapidly after diagnosis. Although targeted treatment of genetic alterations has emerged as an extremely promising approach to human cancers, such as BRAF in metastatic melanoma, it remains unclear that how commonly genomic alterations are influenced in ATC tumorigenesis. In recent years, genome wide approaches have been exploited to find genetic alterations associated with complex diseases, including cancer. Here, we reviewed the comprehensive genetic alterations in ATC and recent approaches in the context of identifying genomic alterations associated with ATC. Since surprisingly few reports have been published on the genome wide study of ATC, this review puts emphasis on the urgent needs of genomic research for the prevention and treatment of ATC.

Evolving approaches to patients with advanced differentiated thyroid cancer

Advanced differentiated thyroid cancer (DTC), defined by clinical characteristics including gross extrathyroidal invasion, distant metastases, radioiodine (RAI) resistance, and avidity for 18-fluorodeoxyglucose (positron emission tomography-positive), is found in approximately 10-20% of patients with DTC. Standard therapy (surgery, RAI, TSH suppression with levothyroxine) is ineffective for many of these patients, as is standard chemotherapy. Our understanding of the molecular mechanisms leading to DTC and the transformation to advanced DTC has rapidly evolved over the past 15-20 years. Newer targeted therapy, specifically inhibitors of intracellular kinase signaling pathways, and cooperative multicenter clinical trials have dramatically changed the therapeutic landscape for patients with advanced DTC. In this review focusing on morbidities, molecules, and medicinals, we present a patient with advanced DTC, explore the genetics and molecular biology of advanced DTC, and review evolving therapies for these patients including multikinase inhibitors, selective kinase inhibitors, and combination therapies.

Apigenin induces c-Myc-mediated apoptosis in FRO anaplastic thyroid carcinoma cells

Apigenin promotes apoptosis in cancer cells. We studied the effect of apigenin on cell survival and c-Myc expression in FRO anaplastic thyroid carcinoma (ATC) cells. Apigenin caused apoptosis via the elevation of c-Myc levels in conjunction with the phosphorylation of p38 and p53. In the c-Myc siRNA-transfected and apigenin-treated cells, compared with the apigenin-treated control cells, apoptosis and phosphorylation of p38 and p53 were ameliorated. In the presence of apigenin, diminution of p38 and p53 did not affect cell survival although apigenin activated the phosphorylation of p38 and p53 via increased c-Myc levels. In conclusion, our results indicate that apigenin induces apoptosis mediated via c-Myc with concomitant phosphorylation of p53 and p38 in FRO ATC cells. These findings suggest that augmented c-Myc acts as a core regulator and is necessary for apigenin-induced apoptosis in FRO ATC cells.

Dickkopf-1 inhibits thyroid cancer cell survival and migration through regulation of β-catenin/E-cadherin signaling

Wnt/β-catenin signaling plays a role in tumorigenesis of human papillary thyroid cancer (PTC). Dickkopf-1 (Dkk-1) is an inhibitor of Wnt/β-catenin signaling. We investigated the therapeutic potential of Dkk-1 in human PTC cell lines, SNU-790, B-CPAP, and BHP10-3. Dkk-1 reversed the aberrant expression of β-catenin from nucleus to membrane and inhibited basal levels of TCF/LEF-dependent transcriptional activities. Furthermore, Dkk-1 inhibited cell viability in a dose-dependent manner and adenoviral transduction of constitutively active β-catenin blocked these effects, thus suggesting that the Dkk-1 anti-tumoral effect is mediated by Wnt/β-catenin signaling. Bromodeoxyuridine assay showed minimal effects of Dkk-1 on cell proliferation. Flow cytometric analysis with Annexin V staining showed marked induction of cell apoptosis by Dkk-1 treatment. Dkk-1 also restored the loss of membranous E-cadherin expression with consequent inhibition of cell migration and invasion. In conclusion, Dkk-1 inhibited the survival and migration of human PTC cells by regulating Wnt/β-catenin signaling and E-cadherin expression.

Proteomic expression profiling of thyroid neoplasms

Thyroid cancer is the most common endocrine neoplasm with multiple histologic subtypes, each associated with different treatments and outcomes. Differentiating benign neoplasms such as follicular adenomas from malignant entities such as follicular carcinomas and papillary carcinoma can be challenging. To define the proteomic profile of different thyroid tumors, we screened an antibody array of 330 features against five thyroid neoplasms: follicular adenoma, follicular carcinoma, papillary carcinoma, anaplastic carcinoma, and medullary carcinoma as well as normal thyroid epithelium. Eight candidate biomarkers; c-erbB-2, Stat5a, Annexin IV, IL-11, RARα, FGF7, Caspase 9, and phospho-c-myc were identified as differentially expressed on the antibody array, and validated with immunohistochemistry on tissue microarrays, with a total of 144 samples of the same variety of thyroid neoplasms. Analysis revealed c-erbB-2, Annexin IV, and Stat5a have potential clinical utility to differentiate follicular adenoma, follicular carcinoma, and papillary carcinoma from each other. By using an antibody array as a discovery platform and a tissue microarray as a first step in validation on a large number of specimens, we have identified new markers that have potential utility in the diagnosis of thyroid neoplasms.

Genetic alterations in poorly differentiated and undifferentiated thyroid carcinomas

Thyroid gland presents a wide spectrum of tumours derived from follicular cells that range from well differentiated, papillary and follicular carcinoma (PTC and FTC, respectively), usually carrying a good prognosis, to the clinically aggressive, poorly differentiated (PDTC) and undifferentiated thyroid carcinoma (UTC).It is usually accepted that PDTC and UTC occur either de novo or progress from a pre-existing well differentiated carcinoma through a multistep process of genetic and epigenetic changes that lead to clonal expansion and neoplastic development. Mutations and epigenetic alterations in PDTC and UTC are far from being totally clarified. Assuming that PDTC and UTC may derive from well differentiated thyroid carcinomas (WDTC), it is expected that some PDTC and UTC would harbour genetic alterations that are typical of PTC and FTC. This is the case for some molecular markers (BRAF and NRAS) that are present in WDTC, PDTC and UTC. Other genes, namely P53, are almost exclusively detected in less differentiated and undifferentiated thyroid tumours, supporting a diagnosis of PDTC or, much more often, UTC. Thyroid-specific rearrangements RET/PTC and PAX8/PPARγ, on the other hand, are rarely found in PDTC and UTC, suggesting that these genetic alterations do not predispose cells to dedifferentiation. In the present review we have summarized the molecular changes associated with the two most aggressive types of thyroid cancer.

Role of the wnt pathway in thyroid cancer

Aberrant activation of Wnt signaling is involved in the development of several epithelial tumors. Wnt signaling includes two major types of pathways: (i) the canonical or Wnt/β-catenin pathway; and (ii) the non-canonical pathways, which do not involve β-catenin stabilization. Among these pathways, the Wnt/β-catenin pathway has received most attention during the past years for its critical role in cancer. A number of publications emphasize the role of the Wnt/β-catenin pathway in thyroid cancer. This pathway plays a crucial role in development and epithelial renewal, and components such as β-catenin and Axin are often mutated in thyroid cancer. Although it is accepted that altered Wnt signaling is a late event in thyroid cell transformation that affects anaplastic thyroid tumors, recent data suggest that it is also altered in papillary thyroid carcinoma (PTC) with RET/PTC mutations. Therefore, the purpose of this review is to summarize the main relevant data of Wnt signaling in thyroid cancer, with special emphasis on the Wnt/β-catenin pathway.

Managing anaplastic thyroid carcinoma

Anaplastic thyroid cancer is one of the most lethal malignancies, with dismal prognosis, resistance to multimodal treatments and a median survival of only 5-6 months. Advances in the discovery of genetic pathway aberrations involved in this aggressive disease have been made, and multiple novel therapies targeting these pathways are undergoing clinical trials. So far, there is no single effective treatment for this disease; however, multimodal therapies with a combination of surgery, radiation and chemotherapy hold some promise. We conducted a PubMed search using the words thyroid neoplasm, anaplastic thyroid carcinoma, anaplastic thyroid cancer and anaplastic thyroid neoplasm, revealing 1673 publications. We review the pathophysiology, current treatments and advances made in identifying the alterations in genetic pathways, as well as novel therapies targeting these pathways.

Molecular genetics and diagnosis of thyroid cancer

Thyroid cancer is a common type of endocrine malignancy, and its incidence has been steadily increasing in many regions of the world. Initiation and progression of thyroid cancer involves multiple genetic and epigenetic alterations, of which mutations leading to the activation of the MAPK and PI3K-AKT signaling pathways are crucial. Common mutations found in thyroid cancer are point mutation of the BRAF and RAS genes as well as RET/PTC and PAX8/PPARγ chromosomal rearrangements. The mutational mechanisms seem to be linked to specific etiologic factors. Chromosomal rearrangements have a strong association with exposure to ionizing radiation and possibly with DNA fragility, whereas point mutations probably arise as a result of chemical mutagenesis. A potential role of dietary iodine excess in the generation of BRAF point mutations has also been proposed. Somatic mutations and other molecular alterations have been recognized as helpful diagnostic and prognostic markers for thyroid cancer and are beginning to be introduced into clinical practice, to offer a valuable tool for the management of patients with thyroid nodules.

Pathogenic mechanisms of deregulated microRNA expression in thyroid carcinomas of follicular origin

Thyroid cancer is one of the most common malignancies of the endocrine system with increasing incidence. The vast majority of thyroid carcinomas derive from thyroid hormone producing follicular cells. Carcinomas of follicular origin are classified as follicular (FTCs), papillary (PTCs), partially differentiated (PDTCs) or anaplastic (ATCs) thyroid carcinomas. While FTCs and PTCs can be managed effectively, ATCs are considered one of the most lethal human cancers. Despite the identification of various genetic alterations, pathogenic mechanisms promoting the progression of thyroid carcinomas are still largely elusive. Over the recent years, aberrant microRNA expression was revealed in all as yet analyzed human cancers, including thyroid carcinomas. In view of the rapidly evolving perception that deregulated microRNA expression serves a pivotal role in tumor progression, microRNAs provide powerful tools for the diagnosis of thyroid carcinomas as well as the identification of potential therapeutic targets. Here, we summarize recent findings on microRNA signatures in thyroid carcinomas of follicular origin and discuss how deregulated microRNA expression could promote cancer progression.

Wnt/beta-Catenin pathway in human glioma: expression pattern and clinical/prognostic correlations

Gliomas are the most common primary intracranial tumors. Understanding the molecular basis of gliomas' progression is required to develop more effective therapies. The Wnt/β-catenin signaling cascade is an important signal transduction pathway in human cancers. Although, overactivation of this pathway is a hallmark of several forms of cancer, little is known about its role in human gliomas. Here, we aimed to determine the clinical significance of Wnt/β-catenin pathway components in gliomas. Immunohistochemical staining was performed to detect the expression patterns of Wnt1, β-catenin and Cyclin D1 in the biopsies from 96 patients with primary gliomas. Kaplan-Meier survival and Cox regression analyses were performed to evaluate the prognosis of patients. Cytoplasmic staining pattern of Wnt1, membranous, cytoplasmic and nuclear accumulation of β-catenin, and nuclear localization of Cyclin D1 were demonstrated by immunohistochemical staining. The Wnt1 expression significantly correlated with the expression of Cyclin D1 (P < 0.0001). The ratio of tumors with a cytoplasmic-nuclear pattern or a cytoplasmic pattern of β-catenin was significantly higher in Wnt1-positive (P < 0.01) and Cyclin D1-positive (P < 0.01) tumors than in Wnt1-negative and Cyclin D1-negative tumors, respectively. The protein expression levels of Wnt1, β-catenin and Cyclin D1 were all positively correlated with the Karnofsky performance scale (KPS) score and World Health Organization (WHO) grades of patients with gliomas. Furthermore, Wnt1, cytoplasmic-nuclear β-catenin and Cyclin D1 status were all the independent prognostic factors for glioma patients (P = 0.01, 0.007 and 0.005, respectively). These results provide convincing evidence that the Wnt/β-catenin pathway correlated closely with the progression of gliomas and might be a novel prognostic marker for this neoplasm.

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.

Intragenic mutations in thyroid cancer

The close genotype-phenotype relationship that characterizes thyroid oncology stimulated the authors to address this article by using a mixed, genetic and phenotypic approach. As such, this article addresses the following aspects of intragenic mutations in thyroid cancer: thyroid stimulating hormone receptor and guanine-nucleotide-binding proteins of the stimulatory family mutations in hyperfunctioning tumors; mutations in RAS and other genes and aneuploidy; PAX8-PPARgamma rearrangements; BRAF mutations; mutations in oxidative phosphorylation and Krebs cycle genes in Hürthle cell tumors; mutations in succinate dehydrogenase genes in medullary carcinoma and C-cell hyperplasia; and mutations in TP53 and other genes in poorly differentiated and anaplastic carcinomas.

Genetic alterations of Wnt signaling pathway-associated genes in hepatocellular carcinoma

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Recently, abnormal activation of the Wnt pathway has been found to be involved in the carcinogenesis of HCC. However, the relationship between genetic changes in the Wnt pathway-associated genes and its protein expression has not been studied in patients with HCC and cirrhotic nodules. The purpose of this study is to explore the contribution of inappropriate activation of the Wnt pathway in liver carcinogenesis.

METHODS

Somatic mutation in exons 3-5 of AXIN1 and exon 3 of beta-catenin were analyzed by direct sequencing and expression of axin and beta-catenin proteins by immunohistochemistry in a series of 36 patients with HCC and cirrhosis.

RESULTS

The AXIN1 and beta-catenin gene mutations were observed in 25% (9/36) and 2.8% (1/36) of HCCs, respectively. All mutations detected in AXIN1 and beta-catenin genes were missense point mutations. Abnormal nuclear expression of beta-catenin was observed in 11 of 36 cases of HCCs (30.6%), but not in cirrhotic nodules. Reduced or absent expression of axin was seen in 24 of 36 HCCs (66.7%). The abnormal expression of beta-catenin and axin proteins was closely correlated with mutations of AXIN1 and beta-catenin (P < 0.0001 and P = 0.008, respectively).

CONCLUSIONS

These data suggest that mutation of AXIN1 gene is a frequent and late event for HCC associated with cirrhosis, and is correlated significantly with abnormal expression of axin and beta-catenin. Therefore, activation of Wnt signaling through AXIN1 rather than beta-catenin mutation might play an important role in liver carcinogenesis.

Common critical pathways in embryogenesis and cancer

Cancer may arise because the developmental programs that create the dramatic alterations in form and structure in embryonic development are potentially corrupted. The cells in our bodies retain memories of these processes and cancer can occur later in life if imperfections occur in the fidelity of these pathways. This article is particularly interested in the phenomenon of epithelial to mesenchymal transition, which occurs in embryogenesis. Also reviewed are the small molecules and pathways that are involved both in homeostasis in adult epithelium and embryogenesis in utero. There are five such pathways in particular selected for review in this article: the Wnt pathway, Hedgehog, Notch, PAR and Bone morphogenetic peptide/TGF beta. These are usually conserved throughout mammalian evolution. Though they have been arbitrarily separated in this article they are not exclusive from one another. Their pathologically altered expression is found especially frequently in childhood tumours where they may recapitulate their developmental role, and in tumours that resemble primitive precursor cells. These pathways are important for selecting cell fates, cellular rearrangements, cytological context and morphologic design in embryology as well as participating in epithelial function in adults.

Derangement of the E-cadherin/catenin complex is involved in transformation of differentiated to anaplastic thyroid carcinoma

BACKGROUND

Anaplastic thyroid cancer arises, or transforms, from pre-existing differentiated thyroid cancer. E-cadherin functions as a cell-cell adhesion molecule that complexes with catenin proteins for function. The objective of this study was to evaluate the change in E-cadherin/beta-catenin expression in the transformation of differentiated to anaplastic thyroid carcinoma.

METHODS

A tissue microarray was constructed from 12 anaplastic thyroid tumors and their adjacent associated differentiated foci. Immunohistochemistry was used to evaluate tumor expression of E-cadherin and beta-catenin.

RESULTS

There was decreased expression of E-cadherin and beta-catenin by the anaplastic tumors when compared with the differentiated thyroid tumors from which they evolved. The expression of E-cadherin and beta-catenin was 92% and 67%, respectively, by the differentiated thyroid carcinoma, and 17% and 50%, respectively, by the anaplastic tumors.

CONCLUSIONS

This report shows that derangement of the E-cadherin/catenin complex is associated with the transformation of differentiated into anaplastic thyroid carcinoma.