An immunohistochemical survey of nine cases of medullary carcinoma of thyroid including reactivity for Cox-1 and Cox-2 enzymes

Assessment of cyclooxygenase-1 and 2 gene expression levels in chronic autoimmune thyroiditis, papillary thyroid carcinoma and nontoxic nodular goitre

INTRODUCTION

The cyclooxygenases are a group of enzymes catalyzing the formation of prostaglandins from arachidonic acid. Cyclooxygenase-1 (COX-1) is a constitutive form, thought to be a "housekeeping gene", with constant levels of expression in most tissues. COX-1 expression in the thyroid gland, except for medullary thyroid carcinoma, has not been a subject of much interest. Cyclooxygenase-2 (COX-2) can be expressed in response to various stimuli, such as mitogens, hormones, cytokines, growth factors. The product of COX-2 activity has been implicated in carcinogenesis. Recent studies have shown that up-regulation of COX-2 is associated with numerous neoplasms. Hereby, we present a study analysing COX-1 and COX-2 expression in papillary thyroid carcinoma (PTC), Hashimoto thyroiditis (HT) and nontoxic nodular goitre (NNG) in fine needle aspiration biopsy (FNAB) washouts and in postoperative tissue.

MATERIAL AND METHODS

Cytological specimens from 120 patients (105 females and 15 males) have been studied, including patients with HT, PTC and NNG. Moreover, we have examined postoperative tissue specimens from 51 patients with PTC and NNG. The methods of molecular analysis have included extraction of total RNA from FNAB cytological material and postoperative tissues, spectrophotometric assessment of the RNA purity, cDNA synthesis in reverse transcription reaction and an analysis of genes expression data by real-time PCR.

RESULTS

The performed analysis has revealed statistically significant higher expression level of the COX-2 gene in PTC group, in comparison with HT and NNG groups (in both cytological and postoperative material). In PTC patients, COX-2 gene expression levels in the material obtained by FNAB were similar to those in the postoperative thyroid tissue. No correlations between COX-2 gene expression level and TNM staging in PTC samples have been observed. There were no correlations between COX-2 expression and anti-TPO antibodies level, or patient's sex or age in the studied groups. Also, there were no correlations of COX-1 gene expression level among PTC, HT and NNG groups.

CONCLUSIONS

Our results suggest that COX-2 gene does not participate in the mechanisms involved in molecular association of HT with PTC. However, in case of PTC itself, it may play some role in neoplastic transformation.

Expression of galectin-3, nm-23, and cyclooxygenase-2 could potentially discriminate between benign and malignant pheochromocytoma

Currently, the only reliable indicator of malignancy in pheochromocytoma is the presence of distant metastasis or extensive local invasion; predicting behavior of pheochromocytoma remains challenging. We aimed to correlate the behavior of pheochromocytoma with its expression of nm-23, cyclooxygenase (COX)-2, and galectin-3 (genes used to predict the course of some neoplastic diseases), evaluated immunohistochemically in 55 paraffin blocks of formalin-fixed pheochromocytoma specimens with confirmed behavior. In 3 (7%) of 44 benign and 7 (64%) of 11 malignant pheochromocytomas, there was negative nm-23 expression (P = .000). COX-2 immunoreactivity was positive in 10 (23%) of benign and 9 (82%) of malignant tumors (P = .000). Galectin-3 was expressed in 5 (11%) of benign and 9 (82%) of malignant pheochromocytomas (P = .000). Negative nm-23, along with positive COX-2 or galectin-3, predicted malignancy with 100% specificity. Dual negativity for galectin-3 and COX-2, along with nm-23 positivity, indicated benign behavior with 100% sensitivity. In early pheochromocytoma, evaluation of nm-23, galectin-3, and COX-2 expression could predict the outcome. Larger studies seem necessary to confirm the potential practical value of our findings.

Cyclooxygenase-2 expression and its association with thyroid lesions

Cyclooxygenase (COX), also known as prostaglandin H synthase, catalyses the formation of prostaglandins from arachidonic acid. It can be expressed in response to various stimuli, such as hormones, mitogens, cytokines, other inflammatory mediators and growth factors. The product of COX-2 activity has been implicated in carcinogenesis by promoting angiogenesis, inhibiting apoptosis, increasing cell invasion and stimulating cell proliferation. It has also been proved that the regular intake of non-steroidal anti-inflammatory drugs (NSAIDs) decreases the risk of developing colon and breast cancers. Thus, it speaks for an important role of COX-2 in growth processes of various types of neoplasms. The connection between COX-2 activity and carcinogenesis has also been examined in human thyroid neoplasms. COX-2 overexpression has been reported in thyroid cancers and also in inflammatory conditions. In consequence there is significant interest whether COX-2 could be of importance as a molecular marker of malignancy in the case of thyroid carcinoma.

Application of immunohistochemistry to thyroid neoplasms

CONTEXT

Thyroid lesions with nodular architecture and follicular pattern of growth often pose difficulties in accurate diagnosis during the assessment of cytologic and histologic specimens. The diagnosis of follicular neoplasm on cytology or of follicular tumor of uncertain malignant potential on histology is likely to cause confusion among clinicians and delay effective management of these lesions. Occasionally, thyroid tumors represent unusual or metastatic lesions and their accurate diagnosis requires immunohistochemical confirmation.

OBJECTIVE

To review the literature on the applications of immunohistochemistry in the differential diagnosis of thyroid tumors.

DATA SOURCES

Relevant articles indexed in PubMed (National Library of Medicine) between 1976 and 2006.

CONCLUSIONS

Our review supports the use of ancillary techniques involving a panel of antibodies suitable for immunohistochemistry and molecular analysis in the assessment of thyroid nodules. These tools can improve diagnostic accuracy when combined with standard morphologic criteria.

Cyclooxygenase isozymes in oral squamous cell carcinoma:a real-time RT-PCR study with clinic pathological correlations

COX-2 expression in tumour cells has been associated with carcinogenesis in many human neoplasms, including head and neck cancer, while the COX-1 isoform of the cyclooxygenase enzyme is constitutively expressed in normal tissues. We measured COX-1 and COX-2 m-RNA expression in samples of both oral cancer and matched oral mucosa from 22 patients by RealTime RT-PCR; clinic pathological data (grading, TNM staging, inflammation, follow-up) of all patients were available for statistical evaluation. Most of the tumor samples in our study expressed at least one cyclooxygenase enzyme (COX-1 or COX-2 mRNA) more than their matched normal oral mucosa (p<0.05), with no correlation with the entity of inflammation, and a significant inverse relationship was found between COX-1 and COX-2 in each sample. Higher levels of COX-2 expression were associated with poor disease-free survival (p<0.05), but not with overall survival and higher tumor stage and grade. Our results suggest that COX-1 may play a role in oral carcinogenesis, and could be regarded as a potential therapeutic target by chemo preventive drugs; moreover, COX-2 expression might be addressed as a new prognostic tool in the clinical management of OSCC.

Cyclooxygenase-2 and inducible nitric oxide synthase expression in thyroid neoplasms and their clinicopathological correlation

To evaluate the expressions of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in thyroid neoplasms in a Korean population, we studied a total of 154 cases: papillary carcinoma of classical type (PTC), 86; follicular adenoma (FA), 21; follicular carcinoma (FC), 35; medullary carcinoma (MC), 3; undifferentiated carcinoma (UC), 5; and Hurthle cell neoplasm (HN), 4. Using immunohistochemical staining, COX-2 expression was detected in 62 (72.1%) PTC specimens, 5 (23.8%) FA specimens, 10 (28.6%) FC specimens, 0 (0.0%) MC specimens, 1 (20.0%) UC specimen, and 3 (75%) HN specimens. iNOS expression was detected in 66 (76.7%) PTC specimens, 4 (19.0%) FA specimens, 13 (37.1%) FC specimens, 0 (0.0%) MC specimens, 3 (60.0%) UC specimens, and 4 (100%) HN specimens. The results showed that COX-2 and iNOS were frequently expressed in the PTC and HN specimens, and iNOS was more frequently overexpressed in the FC specimens than in the FA specimens. In PTC, COX-2 and iNOS were significantly overexpressed in patients over 45 yr of age (p=0.029, p=0.041), and iNOS expression was increased in patients with a large primary tumor (p=0.028). These results suggest that the upregulation of COX-2 and iNOS may contribute to the tumor progression of thyroid gland, particularly in PTC and HN, and iNOS may play an adjuvant role during the tumor progression of FC.

Immunoexpression of multidrug-resistance protein 2 and cyclooxygenase 2 in medullary thyroid carcinomas

CONTEXT

Chemoresistance is due to the expression of multidrug-resistance proteins (MRPs). Cyclooxygenase 2 (COX2), a key enzyme in prostaglandins synthesis, upregulates MRP1. MRP1 is overexpressed in medullary thyroid carcinomas (MTCs), but it is not involved in resistance to doxorubicin and cisplatin, which are commonly used in MTC treatment. MRP2 is specifically involved in resistance to both chemotherapeutic agents, but no data exist on the expression of MRP2 and COX2 in MTC.

OBJECTIVE

To evaluate MRP2 and COX2 expressions in MTC.

DESIGN

We analyzed immunohistochemical expression of MRP2 and COX2 in 12 MTCs and in 6 lymph node metastases. Results were correlated with pTNM and clinical stage.

RESULTS

MRP2 and COX2 expressions were observed only in tumor samples and metastases. Nine MTCs, all pTNM stage T4, were positive for MRP2, whereas 3 MTCs, pTNM stages T2 and T3, were unreactive for MRP2. Six metastatic MTCs at stage T4 showed higher proportion of MRP2+ cells, compared with primary tumors. All 12 MTCs were positive for COX2. Three MTCs, pTNM stage T2 and T3, showed COX2 positivity in all cells. The proportion of COX2+ cells decreased with increased pTNM stage. Four out of 6 metastatic MTCs, stage T4, showed a lower proportion of COX2+ cells, compared with primary tumors. The proportion of MRP2+ cells was inversely related to the proportion of COX2+ cells.

CONCLUSIONS

MRP2 and COX2 expression correlated with pTNM stage. High MRP2 and low COX2 expression may explain resistance to doxorubicin and cisplatin, which is observed in advanced stage MTC. Evaluation of the expression pattern of these 2 proteins may be useful to predict chemosensitivity of these types of tumors.

Cyclooxygenase 1 and 2 expressions in the human thyroid gland

We investigated the expression of COX-1 and COX-2 in normal thyroid tissue, follicular adenoma and well-differentiated thyroid carcinomas and evaluated the difference in COX-1 and COX-2 expression. Ten normal thyroid tissues, ten follicular adenomas, ten papillary carcinomas and ten follicular carcinomas were analyzed by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) for expression of COX-1 and COX-2 mRNA. In addition, immunohistochemical staining was performed to find the expression of the two enzymes in normal thyroid tissues and thyroid neoplasia. Expression of COX-1 mRNA in the normal thyroid tissues, follicular adenomas and both well-differentiated carcinomas was similar and weak. However, COX-2 mRNA was strongly expressed in the well-differentiated carcinomas compared to those of normal thyroid tissue and follicular adenoma.

Role of Immunohistochemistry in the Diagnosis and Progression of Follicular Epithelium-Derived Thyroid Carcinoma

Thyroid carcinoma derived from the thyroid hormone-producing follicular epithelium is the most common thyroid malignancy. While the morphologic diagnosis of conventional papillary thyroid carcinoma is simple, thyroid tumors with a follicular pattern are sometimes a diagnostic challenge. It is in the latter group of thyroid neoplasms that ancillary diagnostic tests such as immunohistochemistry may be of great help. Furthermore, while most differentiated thyroid carcinomas have an excellent prognosis, a subset of these tumors may progress to a poorly or undifferentiated phenotype indicating an aggressive biologic behavior that may lead to systemic spread and death. Application of immunohistochemistry to identify a subset of thyroid carcinoma that may progress to a biologically aggressive phenotype may help in the management of patients with thyroid carcinoma. This review discusses the role of immunohistochemistry in the diagnosis and progression of thyroid carcinoma is discussed.

Practical markers used in the diagnosis of endocrine tumors

Endocrine tumors constitute a large group of neoplasms that are widely dispersed throughout the body. They are made up mostly of neuroendocrine tumors (NE), which are characterized by the presence of secretory granules and production of peptide hormones, and non-NE tumors such as those derived from thyroid follicular cells and adrenal cortical cells. Immunohistochemical markers have been used to characterize these lesions and distinguish them from other histologically similar tumors. Chromogranin and synaptophysin are the most widely used broad-spectrum neuroendocrine tumor markers. The use of antibodies to transcription factors, keratins, and specific peptides is quite valuable in the diagnosis of endocrine tumors. This article reviews the common markers used to characterize endocrine tumors and to recognize tumors involved in the differential diagnosis of specific lesions.