Immunohistochemical demonstration of epidermal growth factor and c-myc oncogene product in normal, benign and malignant thyroid tissues

The expression of c-MYC, Cyclin D1 and Ki-67/MIB-1 in benign and malignant thyroid tissues: is there any diagnostic value?

AIM

To investigate the immunohistochemical (IHC) expression and the diagnostic value of c-MYC, Cyclin D1, and Ki-67∕MIB-1 in follicular adenomas (FAs), follicular carcinomas (FCs), and anaplastic carcinomas (ACs) of the thyroid gland, as well as in their corresponding adjacent, non-neoplastic thyroid tissue (NNTT).

MATERIALS AND METHODS

We conducted a retrospective study of patients who were pathologically diagnosed with FA, FC, or AC after total thyroidectomy. Tissue microarrays with cores taken from neoplastic and adjacent NNTT were constructed. Immunohistochemistry for anti-c-MYC, anti-Cyclin D1, and anti-Ki-67∕MIB-1 antibodies was performed, and the positivity was evaluated.

RESULTS

Twenty-eight specimens were included. Nuclear c-MYC positivity was observed in 4∕11 FCs, and 3∕4 ACs, whereas cytoplasmic c-MYC positivity was found in 16∕24 NNTTs. Globally, there were statistically significant differences between neoplasms and NNTTs, with higher nuclear c-MYC and Cyclin D1 expression observed in neoplasms (p=0.017 and p=0.001, respectively). In contrast, cytoplasmic positivity was seen solely in NNTTs (p=0.001). Cyclin D1 positivity was noted in 11∕13 FAs, 7∕11 FCs, 2∕4 ATCs, and only in one NNTT. A statistically significant correlation was found between MIB1 and c-MYC nuclear positivity (p=0.040).

CONCLUSIONS

Our findings exhibit a clear difference in the IHC expression of c-MYC and Cyclin D1 between different types of thyroid tumors, as well as between the neoplastic and NNTT. Nuclear c-MYC positivity excludes the benign nature of a thyroid lesion, in contrast to cytoplasmic positivity, which demonstrates normal or hyperplastic nature.

Epidermal growth factor receptor activation confers resistance to lenvatinib in thyroid cancer cells

Thyroid cancer is the most common endocrine malignancy. A multitargeted tyrosine kinase inhibitor, lenvatinib, has been used for the treatment of advanced thyroid cancer. To elucidate the mechanism of resistance to lenvatinib in thyroid cancer cells, we established lenvatinib‐resistant sublines and analyzed the molecular mechanisms of resistance. Two thyroid cancer cell lines (TPC‐1 and FRO) were used, and resistant sublines for lenvatinib (TPC‐1/LR, FRO/LR) were established. In TPC‐1/LR, the phosphorylation of epidermal growth factor receptor (EGFR), extracellular signal‐regulated kinase (ERK), and Akt was enhanced whereas in FRO/LR, the phosphorylation of EGFR and downstream signal transduction molecules was not enhanced. The addition of epidermal growth factor decreased sensitivity to lenvatinib in TPC‐1 and FRO. The combination of EGFR inhibitors lapatinib and lenvatinib significantly inhibited the growth of TPC‐1/LR in both in vitro and mouse xenograft models. Short‐term exposure to lenvatinib enhanced the phosphorylation of EGFR in six thyroid cancer cell lines regardless of their histological origin or driver gene mutations; however, phosphorylation of ERK was enhanced in all cells except TPC‐1. A synergistic growth‐inhibitory effect was observed in three thyroid cancer cell lines, including intrinsically lenvatinib‐resistant cells. The results indicate that signal transduction via the EGFR pathway may be involved in the development of lenvatinib resistance in thyroid cancer cells. The inhibition of the EGFR pathway simultaneously by an EGFR inhibitor may have therapeutic potential for overcoming lenvatinib resistance in thyroid cancer.

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.

Expression of the estrogen receptor α, progesterone receptor and epidermal growth factor receptor in papillary thyroid carcinoma tissues

The present study aimed to determine the protein expression, in addition to the clinical value of the expression, of estrogen receptor α (ERα), progesterone receptor (PR) and epidermal growth factor receptor (EGFR) in papillary thyroid carcinoma (PTC). The expression of ERα, PR and EGFR was examined immunohistochemically on paraffin-embedded thyroid tissues obtained from 64 patients with PTC and 14 patients with nodular thyroid goiter (NTG). The expression level of ERα, PR and EGFR was found to be significantly elevated in the PTC tissues compared with the NTG tissues. In addition, the expression of ERα was found to be correlated with the size of PTC tumors. However, there was no significant difference between the expression levels of ERα, PR and EGFR in males and females with PTC. Thus, immunohistochemical evaluation of ERα, PR and EGFR expression in patients with PTC may aid in the prediction of the prognosis of patients with PTC.

Involvement of cysteine-rich protein 61 in the epidermal growth factor-induced migration of human anaplastic thyroid cancer cells

Anaplastic thyroid cancer (ATC) is among the most aggressive types of malignant cancer. Epidermal growth factor (EGF) plays a crucial role in the pathogenesis of ATC, and patients with thyroid carcinoma typically exhibit increased cysteine-rich protein 61 (Cyr61). In this study, we found that EGF treatment induced cell migration, stress fiber formation, Cyr61 mRNA and protein expressions, and Cyr61 protein secretion in ATC cells. The recombinant Cyr61 protein significantly induced cell migration; however, inhibition of Cyr61 activity by a Cyr61-specific antibody abrogated EGF-induced cell migration. EGF treatment also affected epithelial-to-mesenchymal transition (EMT)-related marker protein expression, as evidenced by an increase in vimentin and a decrease in E-cadherin expression. Inhibition of Cyr61 expression by Cyr61 siRNA decreased cell migration and reversed the EMT-related marker protein expression. EGF treatment increased the phosphorylation of the extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB), and finally activated Cyr61 promoter plasmid activity. Our results suggest that Cyr61 is induced by EGF through the ERK/CREB signal pathway and that it plays a crucial role in the migration and invasion of ATC cells; moreover, Cyr61 might be a therapeutic target for metastatic ATC.

Prognostic value of epidermal growth factor receptor, p53 and galectin-3 expression in papillary thyroid carcinoma

OBJECTIVE

The aim of this study was to determine the protein expression and prognostic value of epidermal growth factor receptor (EGFR), p53 and galectin-3 in papillary thyroid carcinoma (PTC).

METHODS

A retrospective analysis was performed using tumour specimens from patients with PTC who underwent thyroidectomy between July 2007 and December 2008. The percentages of tumour cells staining positively for EGFR, galectin-3 and p53 were determined by immunohistochemistry. Associations between protein expression and age, sex, extrathyroidal extension and lymph node metastasis were assessed, together with the total Metastasis, Age, Completeness of resection, Invasion, Size (MACIS) score (a marker of prognosis). MACIS prognostic scores were categorized into four groups.

RESULTS

Data from 168 patients with PTC (mean follow-up, 35 months) were included. EGFR expression was significantly associated with male sex and lymph node metastasis; p53 expression was higher in males than in females; galectin-3 expression was not significantly associated with age, sex, extrathyroidal extension, lymph node metastasis or total MACIS score category, however.

CONCLUSION

Immunohistochemical evaluation of EGFR and p53 expression in patients with PTC may be useful for determining prognosis, in PTC patients.

Anaplastic thyroid carcinoma

Thyroid cancers represent about 1% of all human cancers. Differentiate thyroid carcinomas (DTCs), papillary and follicular cancers, are the most frequent forms, instead Anaplastic Thyroid Carcinoma (ATC) is estimated to comprise 1-2% of thyroid malignancies and it accounts for 14-39% of thyroid cancer deaths. The annual incidence of ATC is about one to two cases/million, with the overall incidence being higher in Europe (and area of endemic goiter) than in USA. ATC has a more complex genotype than DTCs, with chromosomal aberrations present in 85-100% of cases. A small number of gene mutations have been identified, and there appears to be a progression in mutations acquired during dedifferentiation. The mean survival time is around 6 months from diagnosis an outcome that is frequently not altered by treatment. ATC presents with a rapidly growing fixed and hard neck mass, often metastatic local lymph nodes appreciable on examination and/or vocal paralysis. Symptoms may reflect rapid growth of tumor with local invasion and/or compression. The majority of patients with ATC die from aggressive local regional disease, primarily from upper airway respiratory failure. For this reason, aggressive local therapy is indicated in all patients who can tolerate it. Although rarely possible, complete surgical resection gives the best chance of long-term control and improved survival. Therapy options include surgery, external beam radiation therapy, tracheostomy, chemotherapy, and investigational clinical trials. Multimodal or combination therapy should be useful. In fact, surgical debulking of local tumor, combined with external beam radiation therapy and chemotherapy as neoadjuvant (before surgery) or adjuvant (after surgery) therapy, may prevent death from local airway obstruction and as best may slight prolong survival. Investigational clinical trials in phase I or in phase II are actually in running and they include anti-angiogenetic drugs, multi-kinase inhibitor drugs.

EGF and TGF-β1 Effects on Thyroid Function

Normal epithelial thyroid cells in culture are inhibited by TGF-β1. Instead, transformed thyroid cell lines are frequently resistant to its growth inhibitory effect. Loss of TGF-β responsiveness could be due to a reduced expression of TGF-β receptors, as shown in transformed rat thyroid cell lines and in human thyroid tumors, or to alterations of other genes controlling TGF-β signal transduction pathway. However, in thyroid neoplasia, a complex pattern of alterations occurring during transformation and progression has been identified. Functionally, TGF-β1 acts as a tumor suppressor in the early stage of transformation or as a tumor promoter in advanced cancer. This peculiar pleiotropic behaviour of TGF-β may result from cross-talk with signalling pathways mediated by other growth factors, among which EGF-like ligands play an important role. This paper reports evidences on TGF-β1 and EGF systems in thyroid tumors and on the cross-talk between these growth factors in thyroid cancer.

Anaplastic thyroid carcinoma: A comprehensive review of current and future therapeutic options

Anaplastic thyroid carcinoma (ATC) is the rarest, but deadliest histologic type among thyroid malignancies, with a dismal median survival of 3-9 mo. Even though ATC accounts for less than 2% of all thyroid tumors, it is responsible for 14%-39% of thyroid carcinoma-related deaths. ATC clinically presents as a rapidly growing mass in the neck, associated with dyspnoea, dysphagia and vocal cord paralysis. It is usually locally advanced and often metastatic at initial presentation. For operable diseases, the combination of radical surgery with adjuvant radiotherapy or chemotherapy, using agents such as doxorubicin and cisplatin, is the best treatment strategy. Cytotoxic drugs for advanced/metastatic ATC are poorly effective. On the other hand, targeted agents might represent a viable therapeutic option. Axitinib, combretastatin A4, sorafenib and imatinib have been tested in small clinical trials of ATC, with a promising disease control rate ranging from 33% to 75%. Other clinical trials of targeted therapy for thyroid carcinoma are currently ongoing. Biological agents that are under investigation include pazopanib, gefitinib and everolimus. With the very limited therapeutic armamentarium available at the present time, targeted therapy constitutes an exciting new horizon for ATC. In future, biological agents will probably represent the standard of care for this aggressive malignancy, in the same fashion as it has recently occurred for other chemo-refractory tumors, such as kidney and hepatic cancer.

Cytoplasmic Domain of proEGF Affects Distribution and Post-Translational Modification of Microtubuli and Increases Microtubule-Associated Proteins 1b and 2 Production in Human Thyroid Carcinoma Cells

We studied the distribution of transcripts encoding the cytoplasmic domain of the membrane-anchored precursor epidermal growth factor (proEGFcyt) and a novel cytoplasmic proEGF splice isoform with a deleted exon 23 and an out-of-frame fusion of exon 24 (proEGFdel23) in human normal and neoplastic thyroid tissues. In papillary thyroid carcinoma (PTC), coexpression of transcripts encoding for both proEGFcyt and proEGFdel23 correlated with poor differentiation of PTC. To determine potential roles of the cytoplasmic proEGF domain in human thyroid cells, we generated stable transfectants of the human follicular thyroid carcinoma cell line FTC-133 overexpressing the normal cytoplasmic domain proEGFcyt, a truncated proEGFcyt composed of the peptide sequence encoded by exons 22 and 23 (proEGF22.23) and proEGFdel23. The proEGFcyt and proEGF22.23 transfectants displayed significantly reduced proliferation rates, an enlarged cellular phenotype, and alterations in the distribution and post-translational modification of the microtubular system. These transfectants also displayed increased production of microtubule-associated proteins 1b and 2c, which was absent in FTC-133-proEGFdel23 or FTC-133-empty plasmid transfectants. This is the first evidence of an involvement of proEGF cytoplasmic domain in microtubular stability in the human thyroid carcinoma cell line FTC-133 and may suggest a specific role for the cytoplasmic domain of membrane-anchored proEGF, particularly exon 23, in thyroid carcinoma. The up-regulation of proEGFdel23 in poorly differentiated PTC and the exclusive detection of both proEGF isoforms in undifferentiated thyroid carcinoma may indicate an involvement of this novel truncated proEGFdel23 cytoplasmic domain during dedifferentiation processes of human thyroid cells.

Epidermal Growth Factor Receptor (EGFR) Is Overexpressed in Anaplastic Thyroid Cancer, and the EGFR Inhibitor Gefitinib Inhibits the Growth of Anaplastic Thyroid Cancer

PURPOSE

No effective treatment options currently are available to patients with anaplastic thyroid cancer (ATC), resulting in high mortality rates. Epidermal growth factor (EGF) has been shown to play a role in the pathogenesis of many types of cancer, and its receptor (EGFR) provides an attractive target for molecular therapy.

EXPERIMENTAL DESIGN

The expression of EGFR was determined in ATC in vitro and in vivo and in human tissue arrays of ATC. We assessed the potential of the EGFR inhibitor gefitinib ("Iressa," ZD1839) to inhibit EGFR activation in vitro and in vivo, inhibit ATC cellular proliferation, induce apoptosis, and reduce the growth of ATC cells in vivo when administered alone and in combination with paclitaxel.

RESULTS

EGFR was overexpressed in ATC cell lines in vitro and in vivo and in human ATC specimens. Activation of EGFR by EGF was blocked by the addition of gefitinib. In vitro studies showed that gefitinib greatly inhibited cellular proliferation and induced apoptosis in ATC cell lines and slowed tumor growth in a nude mouse model of thyroid carcinoma cells injected subcutaneously.

CONCLUSIONS

ATC cells consistently overexpress EGFR, rendering this receptor a potential target for molecular therapy. Gefitinib effectively blocks activation of EGFR by EGF, inhibits ATC cellular proliferation, and induces apoptosis in vitro. Our in vivo results show that gefitinib has significant antitumor activity against ATC in a subcutaneous nude mouse tumor model and therefore is a potential candidate for human clinical trials.

Molecular pathogenesis of thyroid cancer

A number of molecular abnormalities have been described in association with the progression from normal thyroid tissue to benign adenomas to well-differentiated and finally anaplastic epithelial thyroid cancer. These include upregulation of proliferative factors, such as growth hormones and oncogenes, downregulation of apoptotic and cell-cycle inhibitory factors, such as tumor suppressors, disruption of normal cell-to-cell interactions, and cellular immortalization. The progression model for thyroid carcinoma has not been proven, but evidence suggests that an evolutionary molecular process is involved, especially in the development of follicular thyroid cancers for which there are distinct intermediate phenotypes. We present a comprehensive evaluation of factors involved in thyroid tumorigenesis and attempt to describe preliminary attributes of a progression model. The organization of this model should also provide a template for the incorporation of new information as it is derived from large-scale genomic studies.

Analyses of MYC, ERBB2, and CCND1 genes in benign and malignant thyroid follicular cell tumors by real-time polymerase chain reaction

The roles of the MYC, ERBB2, and CCND1 genes in thyroid carcinogenesis are poorly known. We used real-time quantitative polymerase chain reaction (PCR) assays based on fluorescent TaqMan methodology to quantify MYC, ERBB2, and CCND1 gene amplification and expression in 24 benign tumors (adenomas and goiter nodules) and 12 carcinomas (9 papillary, 2 follicular, and 1 anaplastic) of the thyroid. Real-time PCR is a recently developed method for nucleic acid quantification in homogeneous solutions, and has the potential to become a reference in terms of performance, accuracy, sensitivity, wide dynamic range, excellent interlaboratory agreement, and high throughput capacity, while avoiding the need for tedious post-PCR processing. Overexpression (>5 standard deviations above mean for normal thyroid tissues) of the ERBB2 and CCND1 genes was observed (3.2- to 5.2-fold and 3.8- to 8.4-fold, respectively) in 5 (14%) and 13 (36%) of 36 neoplastic thyroid RNA samples, respectively. Overexpression of the CCND1 gene was observed in both the benign and malignant thyroid tumors, whereas the ERBB2 gene was mainly overexpressed in malignant thyroid tumors. None of the neoplastic thyroid samples overexpressed MYC. No MYC, ERBB2, or CCND1 gene amplification was identified. These results suggest that the CCND1 gene plays an early role and the ERBB2 gene a later role in thyroid tumorigenesis.

Immunocytochemical evaluation of HBME-1, CA 19-9, and CD-15 (Leu-M1) in fine-needle aspirates of thyroid nodules

Overlapping morphologic patterns that may be observed in goiter, follicular adenoma, and papillary carcinoma can limit the cytologic evaluation of the thyroid gland. In an attempt to develop a useful adjunctive test, the immunocytochemical reactivity of HBME-1, carcinoma antigen 19-9 (CA 19-9), and CD-15 (Leu-M1) was tested on 59 cell block preparations from fine-needle aspirations of the thyroid gland. HBME-1 monoclonal antibody was reactive in all 21 papillary carcinomas, in 4 of 18 adenomas, and in 5 of 20 goiters. CA 19-9 was identified in 13 of 21 carcinomas, 1 goiter, but none of the adenomas. CD-15 was present in 15 of 21 carcinomas, 1 goiter, and 1 adenoma. We conclude that HBME-1 is a sensitive marker of papillary thyroid carcinoma. CD-15 and CA 19-9 are less sensitive but more specific. This panel can be useful to help classify morphologically equivocal lesions. As with all immunocytochemical testing, caution must be exercised in the interpretation of results, and correlation made with morphologic and clinical data.

Thyroid carcinoma

During the past years advances have been made in the understanding of the molecular mechanisms involved in the initiation and progression of thyroid carcinoma. Mutations in tumor suppressor genes such as p53 and oncogenes such as N-ras may be important for progression of well-differentiated thyroid carcinomas. Activation of the ret protooncogene located on chromosomal region 10q11.2 has been identified as a key factor in the initiation of papillary and medullary carcinoma. Integration of these discoveries into a prognostic classification scheme may allow us to better predict the biologic behavior of tumors in individual patients. Despite the recent advances in our understanding of the molecular events occurring during thyroid carcinogenesis, major questions persist regarding aspects of patient management. New diagnostic modalities may enable us to noninvasively discriminate between benign and malignant thyroid nodules, and to detect recurrent disease earlier. Although the optimal surgical procedure for well-encapsulated tumors is still debated, recent clinical studies have shown that for those patients with tumors > 1.5 cm, the routine use of RAI and hormone suppression can improve local control and survival rates. Findings in two recent reviews suggest that patients with widely invasive thyroid masses benefit from the surgical removal of all gross tumor. Further investigation is required to define the role of adjuvant radiotherapy and the most appropriate management of unresectable disease. Incorporation of prognostic markers into clinical staging systems should allow surgeons to better tailor their treatment plans for each patient. Translation of recent basic science advances into the clinical arena may also aid in the development of novel treatment strategies for patients with aggressive tumors.

Telomerase activity in benign and malignant thyroid tumors

Thyroid nodules are found in 5% to 10% of the population. While these nodules carry only a 5% to 10% risk of malignancy, tests that complement fine-needle aspiration (FNA) cytology in preoperative diagnosis and risk stratification are lacking. Telomerase is a ribonucleoprotein polymerase with activity found in many malignant tissues, but absent from most normal adult tissue. In this study, we have investigated telomerase activity in 24 thyroid tumors, 14 matched adjacent thyroid tissues, and 3 chronic thyroiditis tissue samples. Using a telomeric repeat amplification protocol (TRAP) assay on frozen tissue, telomerase activity was detected in 11 of 20 thyroid carcinomas, including 10 of 14 papillary carcinomas and a Hurthle cell carcinoma. Telomerase activity was not detected in 4 benign adenomas, 3 follicular carcinomas, or a single case each of medullary and anaplastic thyroid carcinoma. Telomerase activity was detected in 3 of 14 samples of adjacent thyroid tissue from patients with thyroid tumors. Interestingly, all 3 cases of adjacent thyroid tissue that tested positive had a moderate to marked degree of chronic inflammation. In addition, 3 of 3 samples from chronic thyroiditis specimens tested positive for telomerase activity. When tumor invasiveness (vascular and/or capsular) was compared with telomerase activity in papillary carcinomas, only 1 of 4 telomerase-negative tumors was invasive, while 6 of 10 of telomerase-positive tumors were invasive. Moreover, 6 of 7 invasive papillary carcinomas had telomerase activity. In summary, this is the first report of telomerase activity in thyroid tissue and nodules. This activity was detected in a large percentage of papillary thyroid carcinomas, but not benign adenomas, follicular carcinomas, or most normal thyroid tissue. Telomerase activity may also correlate with tumor invasiveness. Further studies will focus on larger numbers of tumors, metastatic tissue, and undifferentiated carcinomas, as well as application of this assay to products from fine-needle aspirates as a potential diagnostic and prognostic marker in thyroid neoplasms.

Immunohistochemical demonstration of c-myc oncogene product in middle ear cholesteatoma

Cholesteatoma epithelium is characterized by a dysregulation with a hyperproliferative growth and altered differentiation. In a variety of cells c-myc oncogene was found to be highly linked to the control of growth and differentiation. Expression of c-myc was studied in cholesteatoma epithelium using a monoclonal antibody directed against the 67 kDa c-myc protein product and the alkaline phosphatase-antialkaline phosphatase method. For quantitative analysis a computer-linked analyzing system was used. In contrast to normal skin, keratinocytes of basal and suprabasal layers showed nuclear staining in cholesteatoma epithelium. The extent of nuclear staining of epithelial cells in the cholesteatomas studied was significantly increased. Concurrent cytoplasmic staining was observed in both skin and cholesteatoma, but with a stronger reactivity in the latter. These findings suggest participation of the c-myc oncogene in cholesteatoma epithelium.

Towards understanding the molecular basis of thyroid cancer

Cancer is a multistep phenomenon and multiple genetic lesions are involved in the emergence of the cancerous lesion. This has best been demonstrated in colonic cancer. The authors review their work and that of others highlighting what is known about thyroid cancer. They implicate ras mutations predominantly in follicular carcinoma, rearrangement of the ret proto-oncogene in papillary carcinoma and the tumor suppressor genes p53 and retinoblastoma gene product in all stages of thyroid carcinoma. They find a low rate of ret proto-oncogene rearrangement in the Saudi population (>5%) as compared to elsewhere in the world (20%). They find TSH receptor message abundance to be predictive of prognosis in thyroid cancer patients. Lastly, they examine whether the abundance of the anti-metastatic gene nm23 message abundance negatively correlated with the tendency of thyroid tumors to metastasize and find that not to be the case in thyroid carcinoma. The study of oncogenes and tumor suppressor genes in the pathogenesis of thyroid cancer is in its infancy; however, rapid progress is being made in identifying genes participating in malignant thyroid cell transformation.

Recent advances in cytometry, cytogenetics and molecular genetics of thyroid tumours and tumour-like lesions

In this review we summarize the most recent advances of flow and image cytometry, cytogenetics and molecular genetics of tumours and tumour-like lesions of the thyroid, especially focusing on the putative relationship between nodular goitres and adenomas, the differential diagnosis of benign and malignant neoplasms and the pathogenesis and prognosis of carcinomas. Data obtained by in situ hybridization and immunohistochemical detection of proliferative markers, metal binding proteins and oncogenes, anti-oncogenes, growth factors and growth factor receptors are also used whenever appropriate.

Expression of growth factors and growth factor receptors in normal and tumorous human thyroid tissues

A number of growth factors have been implicated as stimuli of thyroid cell proliferation; overexpression of these growth factors and/or their receptors may play a role in the growth of thyroid tumors. To determine if immunohistochemical detection of growth factors and/or their receptors correlates with morphological alterations in proliferative lesions of thyroid, we examined the localization of epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha) and their common receptor, EGF-receptor (EGF-R), insulin-like growth factor-1 (IGF-1), IGF-1-receptor (IGF-R) and IGF binding proteins (IGFBP)-1, -2, -3, and -4, nerve growth factor (NGF), and its receptor NGF-receptor (NGF-R), transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (bFGF), in normal thyroid tissue and various thyroid tumors. We applied the streptavidin-biotin technique to formalin-fixed, paraffin-embedded tissues. We studied 8-16 different cases of each of the following: normal human thyroid, multinodular hyperplasia, follicular adenoma, papillary carcinoma, follicular carcinoma, medullary carcinoma, and anaplastic carcinoma. EGF, TGF-alpha, and their receptor EGF-R were widely expressed in normal thyroid and in all the thyroid lesions examined. IGF-1 and IGFBP-1 were diffusely present in all different thyroid tissues as well. There was no difference in staining intensity or distribution that correlated with the pathological process. IGFBP-4 seemed to have a variable expression. IGFBP-2 and -3 were detected only in medullary carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative analysis of p53 and c-myc expression and cell proliferation in human hepatocellular carcinomas--an enhanced immunohistochemical approach

Expression of p53 and c-myc was investigated and compared with cell proliferative activity in a series of 40 hepatocellular carcinomas (HCC), by means of enhanced immunohistochemistry. p53 expression was demonstrated in 5 out of 40 HCC (12.5%) with the incidence increasing in 5 out of 40 HCC (12.5%) with the incidence increasing in proportion to the histological grading of malignancy: thus, 0% of well-differentiated, 6.9% of moderately differentiated and 33.3% of poorly differentiated lesions were positive. The proliferating-cell nuclear antigen (PCNA) labeling index also showed a statistically significant increase with this grading. Distribution patterns of PCNA-positive cell were divided into four types: scatter, marginal, mosaic and diffuse. Four HCC cases, predominantly of the poorly differentiated type, exhibited the diffuse pattern. Generally, p53 overexpression corresponded well with PCNA positivity. In contrast, there was no correlation between c-myc overexpression, found in 19 out of 40 HCC (47.5%), and histological grading of HCC or PCNA labeling index. The distribution pattern of c-myc-positive HCC cells was also different from that of PCNA and p53. Our results suggest that p53 overexpression closely relates to proliferation of HCC cells. Furthermore, there may be a consistent difference in regulatory mechanisms between p53 and c-myc expression in multistep hepatocarcinogenesis.

Prognostic impact of EGF-receptor in papillary thyroid carcinoma

In this study of papillary thyroid carcinomas, immunopositivity for EGF-receptor was present in a majority of the cases (96%), although different staining patterns were observed. A distinct membraneous reaction was found in 46%, whereas cytoplasmatic positivity of various degrees was present in 90% of the cases. Strong cytoplasmic EGF-receptor staining was significantly associated with extra-thyroidal growth of the primary tumour (P = 0.009), and it was furthermore related to decreased recurrence free survival (P = 0.006). Membraneous EGF-receptor staining was not associated with recurrence free survival or patient survival. Multivariate Cox analysis showed that lymph node metastases (P = 0.0009) and cytoplasmic EGF-receptor staining (P = 0.0048) was independent indicators of tumour recurrences in this group of surgically treated papillary thyroid carcinomas.

Demonstration of a TGF-alpha-EGF-receptor autocrine loop and c-myc protein over-expression in papillary thyroid carcinomas

Autocrine growth stimulation has been identified in several types of human cancer. In the present study we wanted to establish whether autocrine stimulation of the epidermal-growth-factor receptor (EGF-r) by its ligand, transforming growth factor alpha (TGF-alpha) occurs in thyroid neoplasia. We examined 190 fresh, frozen thyroid tissue samples from 70 patients by immunohistochemistry with antibodies to EGF-r, TGF-alpha, c-erbB-2 and c-myc. EGF-r expression was detected in 17 out of 19 papillary carcinomas, TGF-alpha expression in 10, and c-erbB-2 expression in 15. No papillary carcinoma expressed TGF-alpha without also expressing EGF-r. Concomitant expression of EGF-r, TGF-alpha and c-erbB-2 was seen in 7 papillary carcinomas. No EGF-r, TGF-alpha or c-erbB-2 immunopositivity was found in normal-appearing thyroid tissue (25 cases), whereas a few of the non-neoplastic lesions (colloid goitres and diffuse hyperplasias) expressed either EGF-r or TGF-alpha. c-myc expression was detectable in all tissue samples, and expression was invariably nuclear. Increased expression was observed in 10 out of 19 papillary carcinomas, and 8 of these also co-expressed EGF-r and TGF-alpha. In situ hybridization confirmed the presence of TGF-alpha mRNA in tumour epithelium of TGF-alpha-immunopositive samples. The concomitant expression of EGF-r, TGF-alpha and TGF-alpha mRNA gives evidence for a TGF-alpha-EGF-r autocrine loop in thyroid papillary carcinomas. The increased c-myc expression may reflect the proliferative advantage of these tumours.

Histologic changes in Graves' thyroid gland after 131I therapy for hyperthyroidism

The effect of 131I therapy was examined in 13 thyroid glands affected by Graves' disease 3 to 29 years after irradiation for hyperthyroidism. All of the patients had clinically palpable thyroid nodules. Two patients were in a latent hypothyroid, 6 in a euthyroid and 5 in a hyperthyroid state. The microscopic changes in the thyroids showed a pattern of multiple adenomatous nodules with cystic changes, marked oxyphilic cell changes with nuclear atypism and various degrees of chronic thyroiditis. Immunohistochemical staining for TG and T4 was negative to mildly positive in these oxyphilic cells and entirely negative for EGF and CEA. The DNA ploidy pattern was diploid pattern in 6 cases. One papillary-type microcarcinoma occurred, but there was no evidence of a relationship between the tumor and the irradiation. The pathologic findings in Graves' thyroid gland after 131I therapy are not specific, but pathologists should differentiate this lesion from adenomatous goiter, which occurs with no apparent cause, or from thyroid carcinoma because of the marked nuclear atypism of this lesion.

Testosterone regulates epidermal growth factor levels in the thyroid gland of hypothyroid mice

The effects of testosterone (TP) and thyroxine (T4) on the level of epidermal growth factor (mEGF) in the thyroid were compared in a hypothyroid mouse model. Groups of five adult female BALB/c mice were given a "severe" hypothyroid regimen consisting of an iodine deficient diet together with oral and s.c propylthiouracil (PTU). Sialoadenectomy or sham operation was performed after 18 days on the hypothyroid regimen. The mice convalesced on normal diet for 5 days and beginning from day 23 received either T4, 1 ug/g or 2 ug/g, s.c daily or TP, 0.3 mg or 0.75 mg, i.m. every third day until day 33, while continuing the hypothyroid regimen. Control mice received normal diet and vehicles for the various injections. The mice were killed on day 33 and thyroidal EGF levels determined by radioimmunoassay. The mean+S.E. levels of mEGF in the thyroid were 10.12 +/- 1.75 ng/mg protein (control), 3.82 +/- 0.67 ng/mg (hypothyroid; p < 0.01), 3.07 +/- 1.52 (T4, 1 ug/g; p < 0.02), 2.59 +/- 0.46 ng/mg (T4, 2 ug/g; p < 0.01), 8.58 +/- 2.48 (TP, 0.3 mg), and 9.65 +/- 1.86 (TP, 0.75 mg). Thus thyroidal mEGF levels decreased significantly in all groups except those subsequently treated with testosterone; T4 was ineffective in reversing the tissue depletion of mEGF in this model. These results show that mEGF levels in the thyroid could be depleted by hypothyroidism and may also be androgen responsive.