Expression of DNA topoisomerase IIalpha in thyroid neoplasia

Integrated Bioinformatics Analysis of Hub Genes and Pathways in Anaplastic Thyroid Carcinomas

Anaplastic thyroid carcinoma (ATC) is a very rare malignancy; the pathogenesis of which is still not fully understood. The aim of the present study was to identify hub genes and pathways in ATC by microarray expression profiling. Two independent datasets (GSE27155 and GSE53072) were downloaded from GEO database. The differentially expressed genes (DEGs) between ATC tissues and normal thyroid tissues were screened out by the limma package and then enriched by gene ontology (GO) and KEGG pathway analysis. The hub genes were selected by protein-protein interaction (PPI) analysis. A total of 141 common upregulated and 87 common downregulated genes were screened out. These DEGs were significantly enriched in the phagosome and NF-kappa B signaling pathway. Through PPI analysis, TOP2A, TYMS, CCNB1, RACGAP1, FEN1, PRC1, and UBE2C were selected as hub genes, which were highly expressed in ATC tissues. TCGA data suggested that the expression levels of TOP2A, TYMS, FEN1, and PRC1 genes were also upregulated in other histological subtypes of thyroid carcinoma. High expression of TOP2A, TYMS, FEN1, PRC1, or UBE2C gene significantly decreased disease-free survival of patients with other thyroid carcinomas. In conclusion, the present study identified several hub genes and pathways, which will contribute to elucidating the pathogenesis of ATC and providing therapeutic targets for ATC.

Aggressive variants of follicular cell-derived thyroid carcinomas: a cytopathologist's perspective

Follicular cell-derived carcinomas of the thyroid gland comprise a heterogeneous group of malignant neoplasms of the thyroid gland with varied histologic appearance and molecular profiles. In most patients, these tumors represent relatively indolent neoplasms; however, certain subtypes/variants behave in an aggressive manner, and the recognition of this subset of tumors is essential because of their variable response to therapy and significant morbidity and mortality. Fine-needle aspiration is considered an essential tool for the diagnosis of suspicious thyroid nodules. In this review, the authors discuss the clinical, histologic, and molecular findings and the prognostic implications of aggressive thyroid neoplasms with emphasis on the characteristic cytomorphologic features on fine-needle aspiration smears.

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.

Detection of the Epstein-Barr virus and DNA-topoisomerase II- α in recurrent and nonrecurrent giant cell lesion of the jawbones

The aims of this study were to determine whether the expression of Topo II-α correlates with presence of EBV in giant cell lesion of the jawbones and whether it is predictive of clinical biologic behavior of these lesions. Paraffin-embedded tissues from 8 recurrent and 7 nonrecurrent cases of bony GCLs and 9 peripheral giant cell lesions (PGCLs) as a control group were assessed for the expression of EBV and Topo II-α using immunohistochemistry. The results showed positive staining for Topo II-α in mononuclear stromal cells (MSCs) and multinucleated giant cells (MGCs). Student t-test showed that mean Topo II-α labelling index (LI) in recurrent cases was significantly higher than that in non-recurrent cases (P = 0.0001). Moreover, Spearman's correlation coefficients method showed a significant correlation between DNA Topo II-α LI and both of gender and site in these lesions. Moderate EBV expression in relation to the highest Topo II-α LI was observed in two cases of GCT. It was concluded that high Topo II-α LIs could be identified as reliable predicators for the clinical behavior of GCLs. Moreover, EBV has no etiological role in the benign CGCLs in contrast to its role in the pathogenesis of GCTs.

Cellular proliferative fraction measured with topoisomerase IIalpha predicts malignancy in endocrine pancreatic tumors

CONTEXT

Endocrine pancreatic tumors (EPTs) are rare lesions with varying biological behavior. Establishing malignancy is a challenge for clinicians and pathologists.

OBJECTIVE

To establish the role of proliferative, apoptotic, angiogenic, and hormonal markers as predictors of malignancy in EPTs.

DESIGN

Paraffin-embedded EPT samples were studied for prognostic markers.

PATIENTS

Twenty-one consecutive patients with a diagnosis of EPT.

MAIN OUTCOME MEASURES

The proliferative fraction (topoisomerase IIalpha), microvascular density (CD34), vascular endothelial growth factor expression, and estrogen receptor-beta (ERbeta) expression were studied by immunohistochemistry on all EPTs. Apoptosis was also assessed with terminal deoxynucleotidyl transferase nick-end labeling.

RESULTS

We identified 13 benign and 8 malignant tumors. Topoisomerase IIalpha was significantly increased in malignant tumors (P =.001), while there were no differences in apoptosis, microvascular density, or vascular endothelial growth factor expression in association with malignancy. No correlation could be identified between microvascular density and vascular endothelial growth factor expression, and ERbeta was not detected. A receiver operating characteristic curve for topoisomerase IIalpha disclosed that above a labeling index of 13, the test had 88% sensitivity and 100% specificity for predicting malignancy.

CONCLUSION

Cellular proliferation measured with topoisomerase IIalpha is a simple prognostic marker for malignancy in EPTs, unlike apoptosis, angiogenesis, or the presence of ERbeta, which were not associated with malignant behavior. These findings designate a defined field for future research on endocrine pancreatic carcinogenesis and a possible target for chemotherapeutic agents.

Is thyroid follicular cancer in Japanese caused by a specific t(2; 3)(q13; p25) translocation generating Pax8-PPAR gamma fusion mRNA?

A recent western study reports that t(2; 3)(q13; p25) translocation resulting in the expression of the Pax8-PPAR gamma fusion gene in patients with thyroid follicular carcinoma (FTC) occurs with high incidence (63%). Furthermore, the products of the fusion gene were shown to suppress the function of PPAR gamma in a predominantly negative manner, conferring them with an oncogenic potential. We examined the expression of this fusion gene in FTC in Japanese patients. From 1989 to 2000, six cases with FTC were surgically treated at our institute. In these carcinoma samples, the expression of mRNAs for the Pax8-PPAR gamma fusion product was analyzed by nested RT-PCR. Their expression was also studied in other thyroid nodules (12 adenomatous goiters, 12 follicular adenomas, 12 papillary carcinomas and 12 normal thyroid tissues) obtained at surgery during the same period. Pax8-PPAR gamma fusion mRNA was not detected in any FTC samples nor in the other samples. Furthermore, none of the 6 FTCs, one follicular adenoma or one normal thyroid analyzed by fluorescence in situ hybridization (FISH) exhibited Pax8-PPAR gamma gene fusion. These findings are in contrast to previous reports and indicate that ethnic background may affect the translocation.

Topoisomerase II alpha and telomerase expression in papillary thyroid carcinomas

BACKGROUND

Altered topoisomerase II alpha (Topo II alpha) expression and telomerase activity (TA) reflect tumour cell growth and malignant transformation.

METHODS

We examined TA by using a TRAP assay and expression of Topo II alpha by immunohistochemical analysis in a series of 27 cases of papillary thyroid carcinoma (PTC).

RESULTS

Topo II alpha labelling index (LI) ranged from 0.1 to 4.2% and was significantly associated with patient age (r=-0.42, p=0.003), with higher levels of Topo II alpha in patients under 40 years. There was no relationship between Topo II alpha LI, AGES score or other clinical outcome. TA was detected in 14 PTC, with relative levels ranging from 1.2 to 102 units. A significant positive correlation between the multiplicity of tumoral foci and the TA levels (p<10(-2)) was noted.

CONCLUSION

We concluded that Topo II alpha cannot be used as a marker of tumour aggressiveness. Furthermore, enhanced Topo II alpha expression in PTCs from patients less than 40 years old suggests that this age group might benefit from Topo II inhibitor chemotherapy.

Y-box binding protein expression in thyroid neoplasms: its linkage with anaplastic transformation

Recent studies have demonstrated that Y-box binding protein (YB-1) regulates the transcription of genes linked to carcinoma progression. In this study, we investigated the expression of this protein in thyroid neoplasms to elucidate its significance. The expression of YB-1 was immunohistochemically investigated using the monoclonal antibody for various thyroid neoplasms. Normal follicles did not overexpress YB-1, and only moderate overexpression of YB-1 was observed in some follicular tumors and papillary carcinoma, especially those of a larger size. In contrast, 92.9% of anaplastic carcinoma strongly overexpressed YB-1. YB-1 immunoreactivity was seen in both cytoplasms and cell nuclei, but the former was more predominant. These findings suggest that YB-1 plays a role in regulating the transcription as well as translation of genes contributing to the anaplastic transformation of thyroid carcinoma.

Diagnosis of "follicular neoplasm": a gray zone in thyroid fine-needle aspiration cytology

The thyroid fine-needle aspiration (FNA) diagnosis of "follicular neoplasm" does not differentiate between a benign and malignant tumor. Often cases diagnosed as "follicular or Hürthle-cell neoplasm" undergo surgical excision for further characterization. The aim of this study was to identify clinical features that may help in predicting malignancy in patients with an FNA diagnosis of follicular neoplasm. One hundred eighty-four cases in 167 patients were diagnosed as "follicular neoplasm" among 1,024 thyroid FNA evaluated with on-site interpretation from 1998-2000. The cases were evaluated for the following variables: histologic diagnosis, age, sex, and size of the nodule. One hundred thirty-nine patients were female, and 28 were male (age range, 23-80 yr). Among 122 patients (67%) undergoing surgical excision (lobectomy, 96; total thyroidectomy, 26), malignancy was identified in 37 cases (31%). Nonpapillary (follicular/Hürthle) carcinoma was diagnosed in 11 (9%), follicular variant of papillary carcinoma in 25, and medullary carcinoma in 1 case. The risk of malignancy was greater in males (47% vs. 29%, P < 0.0004) than females, in nodules measuring 3 cm or more (55% vs. 23%, P < 0.0001), than in nodules measuring less than 3 cm, and in patients 40 or more yr old (20% vs. 10%, P = 0.0001) than in patients younger than 40 years. The diagnosis "follicular neoplasm" is indeterminate, and the majority of cases (70% in the current study) are benign. However, clinical features, including gender, nodule size, and age, can be a part of the decision analysis in selecting patients for surgery.

Potent mitogenicity of the RET/PTC3 oncogene correlates with its prevalence in tall-cell variant of papillary thyroid carcinoma

The tall-cell variant (TCV) of papillary thyroid carcinoma (PTC), characterized by tall cells bearing an oxyphilic cytoplasm, is more clinically aggressive than conventional PTC. RET tyrosine kinase rearrangements, which represent the most frequent genetic alteration in PTC, lead to the recombination of RET with heterologous genes to generate chimeric RET/PTC oncogenes. RET/PTC1 and RET/PTC3 are the most prevalent variants. We have found RET rearrangements in 35.8% of TCV (14 of 39 cases). Whereas the prevalences of RET/PTC1 and RET/PTC3 were almost equal in classic and follicular PTC, all of the TCV-positive cases expressed the RET/PTC3 rearrangement. These findings prompted us to compare RET/PTC3 and RET/PTC1 in an in vitro thyroid model system. We have expressed the two oncogenes in PC Cl 3 rat thyroid epithelial cells and found that RET/PTC3 is endowed with a strikingly more potent mitogenic effect than RET/PTC1. Mechanistically, this difference correlated with an increased signaling activity of RET/PTC3. In conclusion, we postulate that the correlation between the RET/PTC rearrangement type and the aggressiveness of human PTC is related to the efficiency with which the oncogene subtype delivers mitogenic signals to thyroid cells.

DNA topoisomerase IIalpha in multiple myeloma: a marker of cell proliferation and not drug resistance

DNA topoisomerase IIalpha (topo IIalpha) is the target for a number of antineoplastic agents. Down-regulation of this enzyme is one form of drug resistance. Topo IIalpha is also involved in DNA replication and transcription and serves as an indicator of proliferation rate in many human malignancies. This study examines whether topo IIalpha is one of the mechanisms of chemoresistance commonly observed in multiple myeloma (MM) or alternatively, whether topo IIalpha is associated with tumor cell proliferation. Bone marrow (BM) biopsy sections from 72 cases of MM, stratified according to proliferative activity (bromodeoxyuridine uptake), were immunostained for topo IIalpha. Immunoreactivity with an additional marker of drug resistance, glutathione-S-transferase pi, and the proliferation marker Ki-67 were also examined. Topo IIalpha was expressed in 26 (36%) cases and correlated strongly with proliferative activity (P <.001). A role for drug resistance could not be supported, given this strong relationship with proliferation and the finding that glutathione-S-transferase pi expression in 57 (78%) cases was independent of topo IIalpha immunoreactivity. Topo IIalpha was identified in 91 to 100% of highly proliferative tumors, as evaluated by bromodeoxyuridine uptake or Ki-67 reactivity, respectively. Proliferation also correlated with the histologic grade of the MM. Therefore, topo IIalpha immunoreactivity is primarily a marker of cell proliferation in MM and as such is likely to have prognostic significance. Highly proliferative tumors are most likely to be sensitive to chemotherapeutic protocols using anti-topo IIalpha agents.