Immunohistochemical expression of cyclooxygenase 2 in follicular carcinomas of the thyroid

Prognostic Significance of COX-2 Overexpression in BRAF-Mutated Middle Eastern Papillary Thyroid Carcinoma

The cyclooxygenase-2 (COX-2)–prostaglandin E2 (PGE2) pathway has been implicated in carcinogenesis, with BRAF mutation shown to promote PGE2 synthesis. This study was conducted to evaluate COX-2 expression in a large cohort of Middle Eastern papillary thyroid carcinoma (PTC), and further evaluate the prognostic significance of COX-2 expression in strata of BRAF mutation status. BRAF mutation analysis was performed using Sanger sequencing, and COX-2 expression was evaluated immunohistochemically using tissue microarray (TMA). COX-2 overexpression, noted in 43.2% (567/1314) of cases, was significantly associated with poor prognostic markers such as extra-thyroidal extension, lymph-node metastasis, and higher tumor stage. COX-2 was also an independent predictor of poor disease-free survival (DFS). Most notably, the association of COX-2 expression with DFS differed by BRAF mutation status. COX-2 overexpression was associated with poor DFS in BRAF-mutant but not BRAF wild-type PTCs, with a multivariate-adjusted hazard ratio of 2.10 (95% CI = 1.52–2.92; p < 0.0001) for COX-2 overexpressed tumors in BRAF-mutant PTC. In conclusion, the current study shows that COX-2 plays a key role in prognosis of PTC patients, especially in BRAF-mutated tumors. Our data suggest the potential therapeutic role of COX-2 inhibition in patients with BRAF-mutated PTC.

APLP2, RRM2, and PRC1: New Putative Markers for the Differential Diagnosis of Thyroid Follicular Lesions

BACKGROUND

Current methods based on fine-needle aspiration biopsy (FNAB) are not sufficient to distinguish among follicular thyroid lesions, follicular adenoma (FA), follicular thyroid carcinoma (FTC), and the follicular variant of papillary thyroid cancer (FVPTC). Furthermore, none of the immunohistochemical markers currently available are sensitive or specific enough to be used in the clinical setting, necessitating a diagnostic hemithyroidectomy. The aim of this study was to identify proteins of value for differential diagnosis between benign and malignant thyroid follicular lesions.

METHODS

This retrospective analysis is based on an assessment of the immunoexpression of 19 proteins on 81 benign thyroid lesions (FA) and 50 malignant tumors (FTC/FVPTC). The resulting expression profile allowed the design of a scoring system model to improve the differential diagnosis of benign and malignant thyroid lesions. The model was validated using an independent series of 69 FA and 40 FTC and an external series of 40 nodular hyperplasias, and was further tested in a series of 38 FNAB cell blocks.

RESULTS

A model based on the nuclear and cytoplasmic expression of APLP2, RRM2, and PRC1 discriminated between benign and malignant lesions with 100% sensitivity in both main and validation groups, with specificities of 71.3% and 50.7%, respectively. For the nodular hyperplasia series, specificity reached 94.8%. Finally, in FNAB samples, the sensitivity was 100% and the specificity was 45% for discrimination between benign and malignant lesions.

CONCLUSIONS

These findings suggest that the identified APLP2, RRM2, and PRC1 signature could be useful for distinguishing between benign (FA) and malignant (FTC and FVPTC) tumors of the thyroid follicular epithelium.

Loss of estrogen receptor Beta expression in follicular thyroid carcinoma predicts poor outcome

BACKGROUND

Well-differentiated follicular thyroid carcinomas (FTCs) usually act indolently, while aggressively acting tumors are difficult to detect early enough. Estrogen receptors (ERs) have prognostic significance in many cancers. Thyroid diseases, including neoplasms, are associated with the female sex. The prognostic significance of ERs in FTCs has not been reported previously.

METHODS

We studied the role of ERα and ERβ in 83 cases of follicular thyroid adenoma (FTA) and 43 FTC cases, including seven cases of poorly differentiated FTC, obtained from the Department of Surgery, Helsinki University Central Hospital between 1990 and 2009. Patient follow-up was conducted until March 2011. Expression of ERα, ERβ, and MIB-1/Ki-67 was investigated by immunohistochemistry and correlated with clinicopathological characteristics, including survival.

RESULTS

Two major observations were apparent. First, ERβ expression was significantly higher in FTA than in FTC, and it was a stronger differential diagnostic marker than MIB-1/Ki-67. Second, low ERβ expression correlated with poor survival in FTC. All cancer-specific deaths due to FTC were among low ERβ-score patients.

CONCLUSION

ERβ is a differential marker for malignancy and could thus be used as a preoperative tool. FTC patients with a low ERβ score need more thorough follow-up and may benefit from more aggressive treatment.

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.

Diagnostic utility of immunohistochemical panel in various thyroid pathologies

BACKGROUND

For management of thyroid nodules, distinction between benign and malignant tumours is essential. The study was performed to evaluate the diagnostic value of molecular markers in different thyroid tumours.

MATERIALS AND METHODS

Immunohistochemistry for CD56, HBME-1, COX-2, Ki-67, p53 and E-cadherin (E-CAD) was performed in 113 benign and 35 malignant thyroid lesions including 36 follicular adenomas (FA), 77 colloid goitres, 26 papillary thyroid carcinomas (PTC) and 9 follicular carcinomas (FC). The results were scored semiquantitatively by staining intensity (0-3 scale) and percentage of positive cells.

RESULTS

PTC was characterised by decreased E-CAD and CD56 expression in contrast to surrounding benign thyroid tissues. HBME-1 expression was absent in benign thyroid tissues but was notably high in PTC and occasionally in FC. The expression of E-CAD and CD56 in FA was significantly higher than in the surrounding thyroid tissues. No expression of p53 was found in any group. The expression of COX-2 was low in all lesions. The proliferation activity by Ki-67 was generally low; however, it was significantly higher in cancers.

CONCLUSIONS

The panel consisting of three markers, HBME-1, E-CAD and CD56, can be recommended as an adjunct to morphology criteria. HBME-1 is found in malignant lesions only and is the most sensitive and specific single marker in PTC. Decreased expression of E-CAD and CD56 distinguishes PTC from FA and FC. Both FA and FC are characterised by high expression of E-CAD and CD56. The practical use of Ki-67 is difficult due to low values. The role of adhesion factors in thyroid malignancies may be superior in comparison with cell proliferation.

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.

Thyroid Tumors in Dogs and Cats

The clinical presentation and biologic behavior of thyroid tumors vary widely among dogs, cats, and human beings. Although thyroid tumors in dogs are rare, they are most likely to be malignant. Clinical signs are usually the result of impingement on surrounding structures, and clinical hyperthyroidism is rare. In contrast, hyperthyroidism resulting from benign thyroid proliferation is relatively common among older cats. Malignant tumors are extremely uncommon but have high metastatic potential. Irrespective of the tumor's ability to produce functional thyroid hormone, scintigraphy is often helpful in the diagnosis and staging of thyroid tumors in all three species. Treatment with surgery is a reasonable treatment option for noninvasive tumors. Iodine 131 is a well-established treatment for thyroid nodules in cats, but its effectiveness in dogs is controversial. In dogs, external beam radiation therapy has produced more consistent results in affording local tumor control when surgery is not possible.

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.