Identification of Driving ALK Fusion Genes and Genomic Landscape of Medullary Thyroid Cancer

The genetic landscape of medullary thyroid cancer (MTC) is not yet fully understood, although some oncogenic mutations have been identified. To explore genetic profiles of MTCs, formalin-fixed, paraffin-embedded tumor tissues from MTC patients were assayed on the Ion AmpliSeq Cancer Panel v2. Eighty-four sporadic MTC samples and 36 paired normal thyroid tissues were successfully sequenced. We discovered 101 hotspot mutations in 18 genes in the 84 MTC tissue samples. The most common mutation was in the ret proto-oncogene, which occurred in 47 cases followed by mutations in genes encoding Harvey rat sarcoma viral oncogene homolog (N = 14), serine/threonine kinase 11 (N = 11), v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (N = 6), mutL homolog 1 (N = 4), Kiesten rat sarcoma viral oncogene homolog (N = 3) and MET proto-oncogene (N = 3). We also evaluated anaplastic lymphoma kinase (ALK) rearrangement by immunohistochemistry and break-apart fluorescence in situ hybridization (FISH). Two of 98 screened cases were positive for ALK FISH. To identify the genomic breakpoint and 5’ fusion partner of ALK, customized targeted cancer panel sequencing was performed using DNA from tumor samples of the two patients. Glutamine:fructose-6-phosphate transaminase 1 (GFPT1)-ALK and echinoderm microtubule-associated protein-like 4 (EML4)-ALK fusions were identified. Additional PCR analysis, followed by Sanger sequencing, confirmed the GFPT1-ALK fusion, indicating that the fusion is a result of intra-chromosomal translocation or deletion. Notably, a metastatic MTC case harboring the EML4-ALK fusion showed a dramatic response to an ALK inhibitor, crizotinib. In conclusion, we found several genetic mutations in MTC and are the first to identify ALK fusions in MTC. Our results suggest that the EML4-ALK fusion in MTC may be a potential driver mutation and a valid target of ALK inhibitors. Furthermore, the GFPT1-ALK fusion may be a potential candidate for molecular target therapy.     

Expression of obestatin and ghrelin in papillary thyroid carcinoma

Ghrelin and obestatin are two peptide hormones with opposing roles in the control of appetite: orexigenic and anorexigenic, respectively. Loss of appetite is a common, serious complication of many forms of malignancy. The goals of this study were to investigate: (i) whether there are differences in ghrelin and obestatin peptide expression in thyroid tissues from a series of papillary carcinoma cases and normal controls, and (ii) whether there are correlations between tissue ghrelin and obestatin levels in series of papillary carcinoma cases and normal controls. Immunohistochemical analysis showed that in sections of benign human thyroid tissue, anti-ghrelin antibody reacted with intense staining in colloid-filled follicles. In benign thyroid tissues, colloids displayed plentiful dispersion in comparison with papillary microcarcinomas, whereas colloids in malignant thyroid tissues were uncommon. We found markedly lower tissue ghrelin levels in thyroid tissue of patients with papillary carcinomas, compared with normal thyroid tissues (P = 0.001). Immunohistochemical analysis also showed that obestatin in papillary carcinoma stained positively to various degrees. Obestatin tissue levels in papillary carcinomas tended to be slightly higher than those in normal thyroid tissue, but this was not statistically significant (P = 0.29). We also report that thyroid tissue of patients with Hashimoto’s thyroiditis produced ghrelin and obestatin at similar levels as in normal thyroid tissue, even though colloid in Hashimoto’s disease is scarce. We conclude that depressed expression of ghrelin, but not obestatin, is specific to papillary carcinoma, and this difference might constitute a diagnostic tool to differentiate papillary carcinoma from normal thyroid tissue. We currently do not know how these peptides are regulated and what factors are involved in papillary carcinoma, which inhibit the expression of ghrelin but not obestatin. This issue warrants further studies.     

A Comprehensive Comparative Analysis of the Histomorphological Features of ALK-Rearranged Lung Adenocarcinoma Based on Driver Oncogene Mutations: Frequent Expression of Epithelial-Mesenchymal Transition Markers than Other Genotype

Molecular classification of lung cancer correlates well with histomorphological features. However, specific histomorphological features that differentiate anaplastic lymphoma kinase (ALK)-rearranged tumors from ALK-negative tumors have not been fully evaluated. Eighty ALK-rearranged and 213 ALK-negative (91 epidermal growth factor receptor-mutated; 29 K-ras-mutated; 93 triple-negative) resected lung adenocarcinomas were analyzed for several histomorphological parameters and histological subtype. ALK-rearranged tumors were associated with younger age at presentation, frequent nodal metastasis, and higher stage of disease at diagnosis. ALK-rearranged tumors were more likely to show a solid predominant pattern than ALK-negative tumors (43.8%; 35/80; p<0.001). Unlike ALK-negative tumors, a lepidic predominant pattern was not observed in ALK-rearranged tumors (p<0.001). In multivariate analysis, the most significant morphological features that distinguished ALK-rearranged tumors from ALK-negative tumors were cribriform formation (odds ratio [OR], 3.253; p = 0.028), presence of mucin-containing cells (OR, 4.899; p = 0.008), close relationship to adjacent bronchioles (OR, 5.361; p = 0.001), presence of psammoma bodies (OR, 4.026; p = 0.002), and a solid predominant pattern (OR, 13.685; p = 0.023). ALK-rearranged tumors exhibited invasive histomorphological features, aggressive behavior and frequent expression of epithelial-mesenchymal transition markers (loss of E-cadherin and expression of vimentin) compared with other genotype (p = 0.015). Spatial proximity between bronchus and ALK-rearranged tumors and frequent solid histologic subtype with p63 expression may cause diagnostic difficulties to differentiate squamous cell carcinoma in the small biopsy, whereas p40 was rarely expressed in ALK-rearranged adenocarcinoma. Knowledge of these features may improve the diagnostic accuracy and lead to a better understanding of the characteristic behavior of ALK-rearranged tumors.     

Tumor markers and oncogene expression in thyroid cancer using biochemical and immunohistochemical studies.

In 111 thyroid cancer patients consisting of 89 papillary carcinomas, 17 follicular carcinomas, 2 medullary carcinomas, 1 squamous cell carcinoma and 2 malignant lymphomas, the levels of 12 tumor markers, including thyroglobulin (Tg), were measured in the serum by radioimmunoassay and radioimmunoassay related methods. Serum levels of Tg were elevated in 58.6%, those of CA-M26 in 15.7%, CA 19-9 in 5.3%, CT in 3.6%, NSE in 3.6%, CA 15-3 in 2.6%, CA 125 in 2.6%, CEA in 0.9%, CA-M 29 in 0%, ferritin in 0%, SCC in 0% and AFP in 0% of cases. Among the patients, there was a case of thyroid carcinoma secreting thyroglobulin and CA 19-9, both of whose titer decreased after surgery. Immunohistochemical studies were carried out on 57 of the above mentioned patients plus 6 anaplastic carcinomas, 15 adenomas, 5 adenomatous goiters, 6 Hashimoto's thyroiditis, 15 Graves' disease and 15 normal subjects. CA 19-9 was positive in 58% of the papillary carcinomas, EGF in 73% of papillary carcinomas, 67% of anaplastic carcinomas, and 33% of follicular carcinomas, while EGF-R was found in 73% of the papillary carcinomas, and 33% of the follicular carcinomas. Enhanced expression of ras p 21 oncogene and (c-myc oncogene) was demonstrated in 100% (100%) of anaplastic carcinomas, in 100% (67%) of follicular carcinomas and in 63% (90%) of papillary carcinomas. Our results indicate that a better tumor marker is required and more extensive molecular oncology research should be pursued.     

Evaluation of HMFG2 and thyroglobulin in the diagnosis of thyroid fine needle aspiration (FNA)

In order to appraise the usefulness of HMFG₂ and thyroglobulin (Tg) as specific markers for the diagnosis of thyroid disease, we studied 63 FNA smears. Cases tested included 30 benign (nine colloid goitres, six cases of Hashimoto's thyroiditis, six Hürthle cell adenomas, nine follicular adenomas) and 33 malignant lesions (nine follicular carcinomas, 12 papillary carcinomas, nine anaplastic carcinomas, three medullary carcinomas). All cases with malignant lesions except the anaplastic carcinomas were positive for HMFG₂. Immunoreactive cells to HMFG₂ were also found in 15 adenomas out of 30 benign cases. Positive Tg reaction was found in benign and malignant thyroid lesions, except six cases of Hashimoto's thyroiditis, nine anaplastic and three medullary carcinomas. The results obtained indicate that morphology paired with immunocytochemistry can usually depict a more specific profile of thyroid lesions for better evaluation of the pathology.     

Intraosseous inflammatory myofibroblastic tumor of the mandible with a novel <Emphasis Type="Italic">ATIC-ALK</Emphasis> fusion mutation: a case report

Background

Inflammatory myofibroblastic tumor (IMT) is a rare low-grade malignant neoplasm with a predilection for children and young adults, and typically arises in the lung, abdominopelvic region, and retroperitoneum. IMTs in the maxillofacial region are extreme rare. Approximately 50% of IMT harbor rearrangements of the anaplastic lymphoma kinase (ALK) gene at 2p23 with various fusion partners.

Case presentation

We herein report a case of intraosseous IMT of the mandible with a novel ATIC-ALK fusion. Tooth 43 did not erupt after the loss of tooth 83 in an 11-year-old girl with no previous history of trauma. Panoramic tomography showed a unilocular radiolucent lesion in the right anterior mandible resorbing the root of tooth 42 and the medial side of the root of tooth 44. Computed tomography revealed a well- circumscribed 3-cm osteolytic lesion of the right anterior mandible eroding the buccal cortical plate. The entire lesion was curetted out. A histopathological examination revealed the proliferation of plump spindle cells with a storiform architecture and lymphocytes scattered around spindle cells. The spindle cells showed diffuse cytoplasmic staining for ALK by immunohistochemistry. A fluorescence in situ hybridization analysis revealed the translocation of a part of the ALK gene locus at chromosome 2p23. A rapid amplification of cDNA ends analysis confirmed the rearrangement of ALK and identified ATIC as a partner of this ALK fusion mutant.

Conclusion

To the best of our knowledge, this is the first case of intraosseous IMT of the mandible with a novel ATIC-ALK fusion. We also herein reviewed similar tumors reported in the literature.

     

Circulating cytokeratin 19 fragments in patients with benign nodules and carcinomas of the thyroid gland

Cytokeratin 19 (CK19) is an acidic protein of 40 kDa that is part of the cytoskeleton of epithelial cells and is highly expressed by differentiated thyroid carcinomas, mainly of the papillary subtype. The soluble fragments of CK19 (Cyfra 21.1) can be measured by immunometric assays employing specific monoclonal antibodies. The present study was planned to assess the serum expression of Cyfra 21.1 in patients with benign thyroid nodules and thyroid malignancies. We enrolled 135 patients with histologically proven benign thyroid nodules (n=79) and thyroid carcinomas (n=56). No differences were found in serum Cyfra 21.1 levels between patients with benign nodules and patients with carcinomas. When thyroid malignancies were subdivided according to tumor histology, serum Cyfra 21.1 increased significantly from classical differentiated thyroid carcinomas (papillary or follicular) to less differentiated or undifferentiated carcinomas (poorly differentiated or anaplastic). CK19 release into the bloodstream is strongly related to the apoptotic pathway, and particularly to hyperproliferation-related apoptosis. These pathways characterized anaplastic and poorly differentiated thyroid carcinoma but not classical forms of differentiated thyroid carcinoma. Consequently, Cyfra 21.1 may be regarded as a circulating marker of poorly differentiated and anaplastic thyroid carcinoma. Additionally, a role of Cyfra 21.1 as a dedifferentiation marker in patients with classical differentiated thyroid carcinomas may be postulated and should be explored by further focused studies.     

Molecular genetic alterations of FHIT and p53 genes in benign and malignant thyroid gland lesions

Several oncogenes and tumor-suppressor genes are involved either as early or late event in thyroid gland carcinogenesis. Human FHIT (fragile histidine triad) gene is highly conserved gene whose loss of function may be important in the development and/or progression of various types of cancer. We undertook this study to analyze FHIT and p53 gene status in different benignant and malignant thyroid tumors. Status of these genes as well as intensity of apoptosis was analyzed in tumor tissues by molecular genetic methods, immunohistochemistry, and FACS-scan analysis. The majority of the malignant thyroid cancers displayed aberrant expression of FHIT gene, concominant with p53 gene inactivation. This is followed by low rate of apoptosis, which may be important in the development and/or progression of thyroid cancer. We found higher incidence of p53 mutation and aberrant processing of FHIT mRNA in malignant tumors (papillary, follicular, medullary and anaplastic carcinomas) and in those tumors with distant metastasis. The growth of p53(-)/FHIT(-) follicular carcinoma of human origin was much faster in nude mice than p53(+)/FHIT(+) follicular carcinoma, and mice had shorter survival rate. Our results show a correlation between aberrant FHIT and p53 expression, low rate of apoptosis, and malignancy. Concomitant aberration of FHIT gene and p53 could be responsible for development of highly malignant types of thyroid cancer and may be considered as a prognostic marker for these tumors.     

The Role of Podoplanin in the Biology of Differentiated Thyroid Cancers

Podoplanin (PDPN), a mucin-type transmembrane glycoprotein specific to the lymphatic system is expressed in a variety of human cancers, and is regarded as a factor promoting tumor progression. The purpose of this study was to elucidate the molecular role of PDPN in the biology of thyroid cancer cells. PDPN expression was evaluated in primary thyroid carcinomas and thyroid carcinoma cell lines by RT-qPCR, Western blotting, IF and IHC. To examine the role of podoplanin in determining a cell''s malignant potential (cellular migration, invasion, proliferation, adhesion, motility, apoptosis), a thyroid cancer cell line with silenced PDPN expression was used. We observed that PDPN was solely expressed in the cancer cells of 40% of papillary thyroid carcinoma (PTC) tissues. Moreover, PDPN mRNA and protein were highly expressed in PTC-derived TPC1 and BcPAP cell lines but were not detected in follicular thyroid cancer derived cell lines. PDPN knock-down significantly decreased cellular invasion, and modestly reduced cell migration, while proliferation and adhesion were not affected. Our results demonstrate that PDPN mediates the invasive properties of cells derived from papillary thyroid carcinomas, suggesting that podoplanin might promote PTC progression.     

Type 2 chain glycosylation in thyroid carcinomas

Alterations of cell-surface carbohydrates are important for the metastatic behaviour of human carcinomas. Follicular and papillary thyroid carcinomas clinically show a very different metastatic pattern and represent a good model for studies of the metastatic process. We examined the expression of various Le^x-related carbohydrates in 30 primary papillary, 20 primary follicular and 15 primary anaplastic thyroid carcinomas by means of immunohistochemistry. Six metastases from papillary and five from follicular carcinomas were also examined. Morphologically normal thyroid epithelium did not express any of the type 2 carbohydrates. Papillary carcinomas were immunoreactive for several type 2 carbohydrates, including sialyl-Lewis X, in contrast to follicular and anaplastic carcinomas. The metastases showed no significant differences in expression of carbohydrates compared with the primary tumours. We hypothesize that the up-regulation of sialyl-Lewis X and some other related carbohydrates in papillary carcinomas is of importance for the clinical behaviour of these tumours.     

The NADPH oxidase NOX5 protects against apoptosis in ALK-positive anaplastic large-cell lymphoma cell lines

Reactive oxygen species (ROS) are key modulators of apoptosis and carcinogenesis. One of the important sources of ROS is NADPH oxidases (NOXs). The isoform NOX5 is highly expressed in lymphoid tissues, but it has not been detected in any common Hodgkin or non-Hodgkin lymphoma cell lines. In diverse, nonlymphoid malignant cells NOX5 exerts an antiapoptotic effect. Apoptosis suppression is the hallmark feature of a rare type of lymphoma, termed anaplastic lymphoma kinase-positive (ALK⁺) anaplastic large-cell lymphoma (ALCL), and a major factor in the therapy resistance and relapse of ALK⁺ ALCL tumors. We applied RT-PCR and Western blot analysis to detect NOX5 expression in three ALK⁺ ALCL cell lines (Karpas-299, SR-786, SUP-M2). We investigated the role of NOX5 in apoptosis by small-interfering RNA (siRNA)-mediated gene silencing and chemical inhibition of NOX5 using FACS analysis and examining caspase 3 cleavage in Karpas-299 cells. We used immunohistochemistry to detect NOX5 in ALK⁺ ALCL pediatric tumors. NOX5 mRNA was uniquely detected in ALK⁺ ALCL cells, whereas cell lines of other lymphoma classes were devoid of NOX5. Transfection of NOX5-specific siRNA and chemical inhibition of NOX5 abrogated calcium-induced superoxide production and increased caspase 3-mediated apoptosis in Karpas-299 cells. Immunohistochemistry revealed focal NOX5 reactivity in pediatric ALK⁺ ALCL tumor cells. These results indicate that NOX5-derived ROS contribute to apoptosis blockage in ALK⁺ ALCL cell lines and suggest NOX5 as a potential pharmaceutical target to enhance apoptosis and thus to suppress tumor progression and prevent relapse in pediatric ALK⁺ ALCL patients that resist classical therapeutic approaches.     

Role of Dicer1 in thyroid cell proliferation and differentiation

DICER1 plays a central role in the biogenesis of microRNAs and it is important for normal development. Altered microRNA expression and DICER1 dysregulation have been described in several types of tumors, including thyroid carcinomas. Recently, our group identified a new somatic mutation (c.5438A>G; E1813G) within DICER1 gene of an unknown function. Herein, we show that DICER1 is overexpressed, at mRNA level, in a significant-relative number of papillary (70%) and anaplastic (42%) thyroid carcinoma samples, whereas is drastically downregulated in all the analyzed human thyroid carcinoma cell lines (TPC-1, BCPAP, FRO and 8505c) in comparison with normal thyroid tissue samples. Conversely, DICER1 is downregulated, at protein level, in PTC in comparison with normal thyroid tissues. Our data also reveals that DICER1 overexpression positively regulates thyroid cell proliferation, whereas its silencing impairs thyroid cell differentiation. The expression of DICER1 gene mutation (c.5438A>G; E1813G) negatively affects the microRNA machinery and cell proliferation as well as upregulates DICER1 protein levels of thyroid cells but has no impact on thyroid differentiation. In conclusion, DICER1 protein is downregulated in papillary thyroid carcinomas and affects thyroid proliferation and differentiation, while DICER1 gene mutation (c.5438A>G; E1813G) compromises the DICER1 wild-type-mediated microRNA processing and cell proliferation.     

Sensitivity and specificity of fine needle aspiration cytology in the diagnosis of tumors of the thyroid gland

A study of the preoperative fine needle aspiration cytologies in consecutive patients with primary malignant tumors (203 cases) or benign thyroid tumors (217 cases) showed a sensitivity of 0.57 and a specificity of 0.98. The sensitivity of FNA cytology in medullary and undifferentiated carcinomas was 0.82 and 0.84, respectively; none of these were microscopically misdiagnosed. The sensitivity was only 0.58 for papillary carcinomas (excluding occult carcinoma) and 0.42 for follicular carcinoma. Four reasons for these low sensitivities were identified: tumors missed at aspiration, microscopic misinterpretations, diagnoses of cellular atypia and indeterminate diagnoses. Reevaluation of the false diagnoses once more emphasized the problem of distinguishing follicular adenomas from follicular carcinomas. Microscopically undiagnosed papillary carcinomas were either the result of misinterpretations of the characteristic cytomorphologic features or of the smears being misdiagnosed as showing cellular atypia when papillary formations were missing and only one or two of the other cellular criteria were evident. The specificity of FNA cytology of thyroid tumors was found to be high enough to permit surgical intervention after a cytodiagnosis of malignancy.     

Mitochondrial Dynamics Protein Drp1 Is Overexpressed in Oncocytic Thyroid Tumors and Regulates Cancer Cell Migration

Oncocytic cell tumors are characterized by the accumulation of morphologically abnormal mitochondria in their cells, suggesting a role for abnormal mitochondrial biogenesis in oncocytic cell transformation. Little is known about the reason for the dysmorphology of accumulated mitochondria. The proteins regulating the morphology of mitochondria, the "mitochondria-shaping" proteins, can modulate their size and number; however, nothing is known hitherto about a possible involvement of mitochondrial dynamics in oncocytic cell transformation in tumors. Our aim was to assess the status of the mitochondria morphology and its role in oncocytic cell transformation. We therefore evaluated the expression pattern of the main mitochondrial fusion and fission proteins in a series of thyroid cell tumor samples, as well as in thyroid tumor cell lines, with and without oncocytic cell features. The expression of mitochondrial fusion (Opa1, Mfn1 and Mfn2) and fission (Drp1 and Fis1) proteins were evaluated by immunohistochemistry (IHC) in a series of 88 human thyroid tumors. In vitro studies, for comparative purposes and to deepen the study, were performed using TPC1 - a papillary thyroid carcinoma derived cell line—and XTC.UC1, an oncocytic follicular thyroid carcinoma-derived cell line. Both IHC and in vitro protein analyses showed an overall increase in the levels of "mitochondrial-shaping" proteins in oncocytic thyroid tumors. Furthermore, overexpression of the pro-fission protein Drp1 was found to be associated with malignant oncocytic thyroid tumors. Interestingly, genetic and pharmacological blockage of Drp1 activity was able to influence thyroid cancer cells’ migration/invasion ability, a feature of tumor malignancy. In this study we show that unbalanced mitochondrial dynamics characterize the malignant features of thyroid oncocytic cell tumors, and participate in the acquisition of the migrating phenotype.