TSH receptor status of thyroid neoplasms--TaqMan RT-PCR analysis of archival material

Identification of Dysregulated Expression of G Protein Coupled Receptors in Endocrine Tumors by Bioinformatics Analysis: Potential Drug Targets?

Background: Many studies link G protein-coupled receptors (GPCRs) to cancer. Some endocrine tumors are unresponsive to standard treatment and/or require long-term and poorly tolerated treatment. This study explored, by bioinformatics analysis, the tumoral profiling of the GPCR transcriptome to identify potential targets in these tumors aiming at drug repurposing. Methods: We explored the GPCR differentially expressed genes (DEGs) from public datasets (Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA)). The GEO datasets were available for two medullary thyroid cancers (MTCs), eighty-seven pheochromocytomas (PHEOs), sixty-one paragangliomas (PGLs), forty-seven pituitary adenomas and one-hundred-fifty adrenocortical cancers (ACCs). The TCGA dataset covered 92 ACCs. We identified GPCRs targeted by approved drugs from pharmacological databases (ChEMBL and DrugBank). Results: The profiling of dysregulated GPCRs was tumor specific. In MTC, we found 14 GPCR DEGs, including an upregulation of the dopamine receptor (DRD2) and adenosine receptor (ADORA2B), which were the target of many drugs. In PGL, seven GPCR genes were downregulated, including vasopressin receptor (AVPR1A) and PTH receptor (PTH1R), which were targeted by approved drugs. In ACC, PTH1R was also downregulated in both the GEO and TCGA datasets and was the target of osteoporosis drugs. Conclusions: We highlight specific GPCR signatures across the major endocrine tumors. These data could help to identify new opportunities for drug repurposing.

Identification of robust reference genes for studies of gene expression in FFPE melanoma samples and melanoma cell lines

Supplemental Digital Content is available in the text.

There is an urgent need for novel diagnostic melanoma biomarkers that can predict increased risk of metastasis at an early stage. Relative quantification of gene expression is the preferred method for quantitative validation of potential biomarkers. However, this approach relies on robust tissue-specific reference genes. In the melanoma field, this has been an obstacle due to lack of validated reference genes. Accordingly, we aimed to identify robust reference genes for normalization of gene expression in melanoma. The robustness of 24 candidate reference genes was evaluated across 80 formalin-fixed paraffin-embedded melanomas of different thickness, −/+ ulceration, −/+ reported cases of metastases and of different BRAF mutation status using quantitative real-time PCR. The expression of the same genes and their robustness as normalizers was furthermore evaluated across a number of melanoma cell lines. We show that housekeeping genes like GAPDH do not qualify as stand-alone normalizers of genes expression in melanoma. Instead, we have as the first identified a panel of robust reference genes for normalization of gene expression in melanoma tumors and cultured melanoma cells. We recommend using a geometric mean of the expression of CLTA, MRPL19 and ACTB for normalization of gene expression in melanomas and a geometric mean of the expression of CASC3 and RPS2 for normalization of gene expression in melanoma cell lines. Normalization, according to our recommendation will allow for quantitative validation of potential novel melanoma biomarkers by quantitative real-time PCR.

Targeting the TSH receptor in thyroid cancer

Recent advances in the arena of theranostics have necessitated a re-examining of previously established fields. The existing paradigm of therapeutic thyroid-stimulating hormone receptor (TSHR) targeting in the post-surgical management of differentiated thyroid cancer using levothyroxine and recombinant human thyroid-stimulating hormone (TSH) is well understood. However, in an era of personalized medicine, and with an increasing awareness of the risk profile of longstanding pharmacological hyperthyroidism, it is imperative clinicians understand the molecular basis and magnitude of benefit for individual patients. Furthermore, TSHR has been recently re-conceived as a selective target for residual metastatic thyroid cancer, with pilot data demonstrating effective targeting of nanoparticles to thyroid cancers using this receptor as a target. This review examines the evidence for TSHR signaling as an oncogenic pathway and assesses the evidence for ongoing TSHR expression in thyroid cancer metastases. Priorities for further research are highlighted.

WOMEN IN CANCER THEMATIC REVIEW: Thyroid-stimulating hormone in thyroid cancer: does it matter?

Differentiated thyroid cancer is the most common endocrine malignancy and the incidence is increasing rapidly worldwide. Appropriate diagnosis and post-treatment monitoring of patients with thyroid tumours are critical. Fine needle aspiration cytology remains the gold standard for diagnosing thyroid cancer, and although there have been significant refinements to this technique, diagnostic surgery is often required for patients suspected to have malignancy. Serum thyroid-stimulating hormone (TSH) is higher in patients with malignant thyroid nodules than in those with benign disease, and TSH is proportionally increased in more aggressive tumours. Importantly, we have shown that the pre-operative serum TSH concentration independently predicts the presence of malignancy in subjects presenting with thyroid nodules. Establishing the use of TSH measurements in algorithms identifying high-risk thyroid nodules in routine clinical practice represents an exciting, cost-efficient and non-invasive approach to optimise thyroid cancer diagnosis. Binding of TSH to receptors on thyrocytes stimulates a number of growth promoting pathways both in normal and malignant thyroid cells, and TSH suppression with high doses of levothyroxine is routinely used after thyroidectomy to prevent cancer recurrence, especially in high-risk tumours. This review examines the relationship between serum TSH and thyroid cancer and reflects on the clinical potential of TSH measurements in diagnosis and disease monitoring.

BRAF T1799A Mutation Occurring in a Case of Malignant Struma Ovarii

Struma ovarii is an extremely rare tumor that occasionally undergoes malignant transformation. Because struma ovarii is composed of thyroid tissue, it is conceivable that the pathogenetic events involved in thyroid follicular transformation may take place also in struma ovarii. The authors describe a case of a classical variant of papillary thyroid carcinoma arising in a struma ovarii of a 22-year-old female. The tumor was heterozygous for BRAF T1799A mutation. No ret/ PTC-1 or ret/PTC-3 rearrangements were detected. This finding would suggest that malignant struma ovarii is similar histologically and genetically to primary papillary thyroid carcinoma.

TSH signaling overcomes B-RafV600E-induced senescence in papillary thyroid carcinogenesis through regulation of DUSP6

B-RafV600E oncogene mutation occurs most commonly in papillary thyroid carcinoma (PTC) and is associated with tumor initiation. However, a genetic modification by B-RafV600E in thyrocytes results in oncogene-induced senescence (OIS). In the present study, we explored the factors involved in the senescence overcome program in PTC. First of all, we observed down-regulation of p-extracellular signal-regulated kinases 1/2 and up-regulation of dual specific phosphatase 6 (DUSP6) in the PTC with B-RafV600E mutation. DUSP6 overexpression in vitro induced extracellular signal-regulated kinases 1/2 dephosphorylation and inhibited B-RafV600E–induced senescence in thyrocytes. Although DUSP6 protein was degraded by B-RafV600E–induced reactive oxygen species (ROS), thyroid-stimulating hormone (TSH) stabilized DUSP6 protein by increasing Mn superoxide dismutase expression and inhibited B-RafV600E–induced senescence. Although serum TSH was not increased, its receptor was markedly upregulated in PTC with B-RafV600E. Furthermore, TSH together with DUSP6 reactivated Ras signaling, resulted in activation of Ras/AKT/glycogen synthase kinase 3β, and stabilized c-Myc protein by inhibiting its degradation. These observations led us to conclude that increased TSH signaling overcomes OIS and is essential for B-RafV600E–induced papillary thyroid carcinogenesis.

Different expression of TSH receptor and NIS genes in thyroid cancer: role of epigenetics

The TSH receptor (TSHR) and sodium/iodide symporter (NIS) are key players in radioiodine-based treatment of differentiated thyroid cancers. While NIS (SLC5AS) expression is diminished/lost in most thyroid tumors, TSHR is usually preserved. To examine the mechanisms that regulate the expression of NIS and TSHR genes in thyroid tumor cells, we analyzed their expression after inhibition of ras-BRAF-MAPK and PI3K-Akt-mTOR pathways and the epigenetic control occurring at the gene promoter level in four human thyroid cancer cell lines. Quantitative real-time PCR was used to measure NIS and TSHR mRNA in thyroid cancer cell lines (TPC-1, BCPAP, WRO, and FTC-133). Western blotting was used to assess the levels of total and phosphorylated ERK and Akt. Chromatin immunoprecipitation was performed for investigating histone post-translational modifications of the TSHR and NIS genes. ERK and Akt inhibitors elicited different responses of the cells in terms of TSHR and NIS mRNA levels. Akt inhibition increased NIS transcript levels and reduced those of TSHR in FTC-133 cells but had no significant effects in BCPAP. ERK inhibition increased the expression of both genes in BCPAP cells but had no effects in FTC-133. Histone post-translational modifications observed in the basal state of the four cell lines as well as in BCPAP treated with ERK inhibitor and FTC-133 treated with Akt inhibitor show cell- and gene-specific differences. In conclusion, our data indicate that in thyroid cancer cells the expression of TSHR and NIS genes is differently controlled by multiple mechanisms, including epigenetic events elicited by major signaling pathways involved in thyroid tumorigenesis.

Circulating cell-free DNA, SLC5A8 and SLC26A4 hypermethylation, BRAF(V600E): A non-invasive tool panel for early detection of thyroid cancer

PURPOSE

In the latest years, high levels of circulating cell-free DNA (cf-DNA) have been found to be associated with cancer diagnosis and progression, and cf-DNA has become a potential candidate as biomarker for tumor detection. cf-DNA has been investigated in plasma or serum of many tumor patients affected by different malignancies, but not yet in thyroid cancer (TC). Furthermore, in TC cells the capability to metabolize iodine is frequently lost. SLC5A8 and SLC26A4 genes are both involved in the iodine metabolism, and SLC5A8 hypermethylation status is associated with the BRAF(V600E) mutation, which is the most frequent genetic event underlying the development of papillary TC. The aim of our study is the development of a new non-invasive tool for the diagnosis and prognosis of TC based on cf-DNA, SLC5A8 and SLC26A4 hypermethylation, and BRAF(V600E) analysis.

METHODS

cf-DNA was measured by quantitative real-time PCR in nine cases of anaplastic thyroid cancer (ATC), 58 medullary thyroid cancers (MTC), five of synchronous medullary and follicular thyroid cancers (SMFC), 23 follicular adenomas (FA), 86 papillary thyroid cancers (PTC). A control group of 19 healthy subjects was taken. Moreover, in the PTC group we analyze the state of hypermethylation of SLC5A8 and SLC26A4, BRAF(V600E) mutation, and their involvement in the loss of function of the thyroid.

RESULTS

cf-DNA showed a high ability to discriminate healthy individuals from cancer patients. cf-DNAALU83 and cf-DNAALU244 values were significantly correlated with the histological type of TC (P-value < 0.0001). A significant increase in the amount of cf-DNAALU83 and cf-DNAALU244 when methylation occurs was observed (P-value = 0.02). A correlation between BRAF(V600E) and cf-DNAALU244/ALU83 was also found (P-value = 0.02).

CONCLUSIONS

According to our experimental results, the panel including cf-DNA, SLC5A8 and SLC26A4 hypermethylation, and BRAF(V600E) analysis appears easy, reproducible, and non-invasive for the diagnosis on TC. Its possible implication in clinical setting remains to be elucidated.

Semi-nested real-time reverse transcription polymerase chain reaction methods for the successful quantitation of cytokeratin mRNA expression levels for the subtyping of non-small-cell lung carcinoma using paraffin-embedded and microdissected lung biopsy specimens

In patients with inoperable advanced non-small cell lung carcinomas (NSCLCs), histological subtyping using small-mount biopsy specimens was often required to decide the indications for drug treatment. The aim of this study was to assess the utility of highly sensitive mRNA quantitation for the subtyping of advanced NSCLC using small formalin fixing and paraffin embedding (FFPE) biopsy samples. Cytokeratin (CK) 6, CK7, CK14, CK18, and thyroid transcription factor (TTF)-1 mRNA expression levels were measured using semi-nested real-time quantitative (snq) reverse-transcribed polymerase chain reaction (RT-PCR) in microdissected tumor cells collected from 52 lung biopsies. Our results using the present snqRT-PCR method showed an improvement in mRNA quantitation from small FFPE samples, and the mRNA expression level using snqRT-PCR was correlated with the immunohistochemical protein expression level. CK7, CK18, and TTF-1 mRNA were expressed at significantly higher levels (P<0.05) in adenocarcinoma (AD) than in squamous cell carcinoma (SQ), while CK6 and CK14 mRNA expression was significantly higher (P<0.05) in SQ than in AD. Each histology-specific CK, particularly CK18 in AD and CK6 in SQ, were shown to be correlated with a poor prognosis (P=0.02, 0.02, respectively). Our results demonstrated that a quantitative CK subtype mRNA analysis from lung biopsy samples can be useful for predicting the histology subtype and prognosis of advanced NSCLC.

Papillary thyroid carcinoma in one of identical twin patients with Pendred syndrome

Pendred syndrome is an autosomal recessive disorder characterized by sensorineural deafness, a partial defect in iodide organification, and dyshormonogenetic goiter. Several cases of Pendred syndrome with follicular thyroid carcinomas were reported previously. Here we report identical twin patients with Pendred syndrome, who had thyroid tumors with distinct histopathological findings. 34-year-old identical twins with congenital deafness and goiter were referred to our hospital with complaint of neck discomfort. The genetic testing showed that these twin patients were compound heterozygotes carrying the same two mutations in the Pendred's syndrome (PDS / SLC26A4) gene (c2168A > G and ins2110GCTGG), which confirmed the diagnoses of Pendred syndrome. They underwent thyroidectomy. Histological examination of the thyroid tumors resected from these twin patients revealed follicular variant of papillary thyroid carcinoma, and diffuse and nodular goiter without any evidence of malignancy, respectively. To our knowledge, the former is the first case of follicular variant of papillary thyroid carcinoma in Pendred Syndrome.

RT-PCR-based gene expression profiling for cancer biomarker discovery from fixed, paraffin-embedded tissues

A molecular test providing clear identification of individuals at highest risk for developing metastatic disease from among early stage breast cancer patients has proven to be of great benefit in breast cancer treatment planning and therapeutic management. Patients with high risk of disease recurrence can also get an estimate of the magnitude of benefit to be gained by adding chemotherapy to surgery and hormonal therapy. Developing this clinical test was made possible by the availability of technologies capable of identifying molecular biomarkers from the gene expression profiles of preserved surgical specimens. Molecular tests such as the Oncotype DX(®) breast cancer test are proving to be more effective tools for individualized patient stratification and treatment planning than traditional methods such as patient demographic variables and histopathology indicators.Molecular biomarkers must be clinically validated before they can be effectively applied toward patient management in clinical practice. The most effective and efficient means of clinical validation is to use archived surgical specimens annotated with well-characterized clinical outcomes. However, carrying out this type of clinical study requires optimization of traditional molecular expression profiling techniques to analyze RNA from fixed, paraffin-embedded (FPE) tissues. In order to develop our clinically validated breast cancer assay, we modified molecular methods for RNA extraction, RNA quantitation, reverse transcription, and quantitative PCR to work optimally in archived clinical samples. Here, we present an updated description of current best practices for isolating both mRNA and microRNA from FPE tissues for RT-PCR-based expression profiling.

Rt-PCR gene expression profiling of RNA from paraffin-embedded tissues prepared using a range of different fixatives and conditions

Although RNA is isolated from archival fixed tissues routinely for reverse transcription polymerase chain reaction (RT-PCR) and microarray analyses to identify biomarkers of cancer prognosis and therapeutic response prediction, the sensitivity of these molecular profiling methods to variability in pathology tissue processing has not been described in depth. As increasing numbers of expression analysis studies using fixed archival tumor specimens are reported, it is important to examine how dependent these results are on tissue-processing methods.We carried out a series of studies to systematically evaluate the effects of various tissue-fixation reagents and protocols on RNA quality and RT-PCR gene expression profiles. Human placenta was selected as a model specimen for these studies since it is relatively easily obtained and has proliferative and invasive qualities similar to solid tumors. In addition, each specimen is relatively homogeneous and large enough to provide sufficient tissue to systematically compare a range of fixation conditions and reagents, thereby avoiding the variability inherent in studying collections of tumor tissue specimens. Since anatomical pathology laboratories generally offer hundreds of different tissue-fixation protocols, we focused on fixation reagents and conditions used to process the most common solid tumors for primary cancer diagnosis. Fresh placentas donated under an IRB-approved protocol were collected at delivery and immediately submerged in cold saline for transport to a central pathology laboratory for processing. RNA was extracted from each specimen, quantified, and analyzed for size distribution and analytical performance using a panel of 24 RT-PCR gene expression assays. We found that different tissue-fixation reagents and tissue-processing conditions resulted in widely varying RNA extraction yields and extents of RNA fragmentation. However, the RNA extraction method and RT-PCR assays could be optimized to achieve successful gene expression analysis for nearly all fixation conditions represented in these studies.

Oncofetal fibronectin mRNA is highly abundant in the blood of patients with papillary thyroid carcinoma and correlates with high-serum thyroid-stimulating hormone levels

BACKGROUND

Papillary thyroid carcinoma (PTC) cells express oncofetal fibronectin (onfFN) mRNA, which may be useful to detect circulating tumor cells. The objective of this study was to determine the fraction of PTC patients having onfFN mRNA in their peripheral blood and to determine if onfFN mRNA levels are correlated with the status of the disease or with thyroid-stimulating hormone (TSH) serum concentrations.

METHODS

This study included 95 PTC patients, who were previously treated by thyroidectomy and radioactive iodine administration. Patients were examined by cervical sonography, whole-body (131)I scintigraphy, thyroglobulin measurement, and onfFN mRNA quantification both when they were being treated with L-thyroxine (L-T4) and after L-T4 withdrawal. The mean value for onfFN mRNA in blood from 25 healthy subjects was used as control for the onfFN mRNA assay.

RESULTS

After L-T4 withdrawal, serum TSH levels rose and onfFN mRNA was found in the peripheral blood of 33 of 64 (52%) disease-free patients, 15 of 23 (65%) patients with local residual disease, and 6 of 8 (75%) patients with known local or distant metastases. Continuous administration of L-T4 repressed serum TSH. In this state none of 17 (0%) disease-free patients and 1 of 4 (25%) patients with local residual disease had an elevated onfFN mRNA level, and 2 of 4 (50%) patients with metastasis had positive tests for serum onfFN mRNA.

CONCLUSIONS

onfFN transcripts are highly abundant in the peripheral blood of patients with PTC. L-T4 withdrawal, which produced elevated serum TSH concentrations in these athyroidic patients, markedly increased the fraction with positive tests for serum onfFN mRNA at all stages of the disease. Analyzing onfFN mRNA in the absence of a TSH stimulus allows a much better discrimination of different states of PTC disease and, based on current concepts of the significance of circulating mRNA, may be a useful tool to detect circulating thyroid cancer cells.

Induction of thyroid gene expression and radioiodine uptake in thyroid cancer cells by targeting major signaling pathways

CONTEXT

Radioiodine ablation is commonly used to treat thyroid cancer, but a major challenge is often the loss of radioiodine avidity of the cancer caused by aberrant silencing of iodide-handling genes.

OBJECTIVES

This study was conducted to test the therapeutic potential of targeting the aberrantly activated MAPK and PI3K/Akt/mTOR pathways and histone deacetylase to restore radioiodine avidity in thyroid cancer cells.

EXPERIMENTAL DESIGN

We tested the effects of specific inhibitors targeting these pathways/molecules that had established clinical applicability, including the MAPK kinase inhibitor RDEA119, mTOR inhibitor temsirolimus, Akt inhibitor perifosine, and histone deacetylase inhibitor SAHA, individually or in combinations, on the expression of iodide-handling genes and radioiodide uptake in a large panel of thyroid cancer cell lines.

RESULTS

The expression of a large number of iodide-handling genes could be restored, particularly the sodium/iodide symporter, TSH receptor, and thyroperoxidase, by treating cells with these inhibitors. The effect was particularly robust and synergistic when combinations of inhibitors containing SAHA were used. Robust expression of sodium/iodide symporter in the cell membrane, which plays the most important role in iodide uptake in thyroid cells, was confirmed by immunofluorescent microscopy. Radioiodide uptake by cells was correspondingly induced under these conditions. Thyroid gene expression and radioiodide uptake could both be further enhanced by TSH.

CONCLUSIONS

Targeting major signaling pathways could restore thyroid gene expression and radioiodide uptake in thyroid cancer cells. Further studies are warranted to test this therapeutic potential in restoring radioiodine avidity of thyroid cancer cells for effective ablation treatment.

Thyroid cancer in young adults

The incidence of thyroid cancer in young adults is rising. Differentiated carcinoma (ie, papillary, follicular, and their variants) and medullary thyroid carcinoma (MTC) represent the two most common subtypes, with differing etiologies, prognoses, and management strategies. Ultrasound (US)-guided fine needle aspiration (FNA) is the best initial test for evaluating a nodule or mass suspicious for malignancy. Tumor histology, in addition to radiographic findings and clinical presentation, guides surgical management, the need for adjuvant therapies, and the optimal approach to long-term follow-up. Radioactive iodine (RAI) is used to reduce recurrence and improve survival for differentiated thyroid carcinomas (DTCs). Emerging systemic therapies provide options for patients with progressive metastatic MTC or radio-resistant DTC. Overall, the prognosis for the most common thyroid malignancy, papillary thyroid carcinoma (PTC), is excellent. The treatment of young adult thyroid cancer patients occurs optimally as part of a multidisciplinary coordination of care.

Recent advances in molecular biology of thyroid cancer and their clinical implications

Thyroid cancer is the most common endocrine malignancy. With a rapidly rising incidence in recent years, novel efficient management strategies are increasingly needed for this cancer. Remarkable advances have occurred in understanding several major biologic areas of thyroid cancer, including the molecular alterations for the loss of radioiodine avidity of thyroid cancer, the pathogenic role of the MAP kinase and PI3K/Akt pathways and their related genetic alterations, and the aberrant methylation of functionally important genes in thyroid tumorigenesis and pathogenesis. These exciting advances provide unprecedented opportunities for the development of molecular-based novel diagnostic, prognostic, and therapeutic strategies for thyroid cancer.

RET/PTC rearrangement occurring in primary peritoneal carcinoma

RET/PTC rearrangements are initiating events in the development of a significant proportion of papillary thyroid carcinomas. Activated RET/PTC mutations are thought to be restricted to thyroid disease, but this study proposes that these events may also occur in nonthyroid tumors. A total of 57 nonthyroid papillary tumors were examined for RET/PTC rearrangements using interphase fluorescence in situ hybridization, Taqman reverse transcriptase polymerase chain reaction, and immunohistochemistry. Taqman single nucleotide polymorphism detection was used to analyze for expression of mutated BRAF T1799A. In all, 20% (3/15) of primary peritoneal carcinoma had detectable RET/PTC1 rearrangements by all 3 methodologies. A further case of similar histotype had an alternate RET/ PTC rearrangement. No RET/PTC1 rearrangements were detected in the remaining tumor cohort. All 57 tumors were homozygous for wild-type BRAF. The results indicate that RET/PTC rearrangements occur in a small subset of nonthyroid papillary tumors. These rearrangements may not be directly implicated in tumor growth; rather representing "passenger" mutations reflecting RET instability in secondary tumor subclones.

Tumor marker discovery by expression profiling RNA from formalin fixed paraffin embedded tissues

Clear identification among early-stage cancer patients of those at highest risk of having metastatic disease would be of great benefit in treatment planning and management. Considerable additional benefit would accrue to high-risk patients if their responses to specific therapeutic alternatives could be predicted. Molecular biomarkers in the form of gene expression profiles are proving to be more effective tools for both prognostic and predictive patient stratification than more traditional methods such as patient demographics and histopathology indicators. Such biomarkers must be clinically validated before they can be effectively used to manage patients in clinical studies or clinical practice. This can be most efficiently accomplished by analyzing archived clinical samples with well-characterized clinical outcomes. Doing studies of this type requires reoptimization of traditional molecular expression profiling techniques to analyze RNA from fixed paraffin-embedded tissues. We have modified molecular methods for RNA extraction, RNA quantification, reverse transcription, and quantitative PCR to work optimally in archived clinical samples in order to develop a clinically validated assay for breast cancer prognosis and prediction of patient response to hormonal and chemotherapy.

Gene expression in RET/PTC3 and E7 transgenic mouse thyroids: RET/PTC3 but not E7 tumors are partial and transient models of human papillary thyroid cancers

We studied gene expression profiles in two mouse models of human thyroid carcinoma: the Tg-RET/PTC3 (RP3) and Tg-E7 mice. RP3 fusion gene is the most frequent mutation found in the first wave post-Chernobyl papillary thyroid cancers (PTCs). E7 is an oncoprotein derived from the human papillomavirus 16 responsible for most cervical carcinoma in women. Both transgenic mice develop thyroid hyperplasia followed by solid differentiated carcinoma in older animals. To understand the different steps leading to carcinoma, we analyzed thyroid gene expression in both strains at different ages by microarray technology. Important biological processes were differentially regulated in the two tumor types. In E7 thyroids, cell cycle was the most up-regulated process, an observation consistent with the huge size of these tumors. In RP3 thyroids, contrary to E7 tumors, several human PTC characteristics were observed: overexpression of many immune-related genes, regulation of human PTC markers, up-regulation of EGF-like growth factors and significant regulation of angiogenesis and extracellular matrix remodeling-related genes. However, similarities were incomplete; they did not concern the overall gene expression and were not conserved in old animals. Therefore, RP3 tumors are partial and transient models of human PTC. They constitute a good model, especially in young animals, to study the respective role of the biological processes shared with human PTC and will allow testing drugs targeting these validated variables.

Ghrelin enhances the proliferating effect of thyroid stimulating hormone in FRTL-5 thyroid cells

Ghrelin regulates cell proliferation through the growth hormone secretagogue receptor (GHS-R). We confirmed the expression of GHS-R in FRTL-5 thyroid cells and investigated the effects of ghrelin in thyrocytes using FRTL-5 cells. Ghrelin increased intracellular calcium levels but not intracellular cyclic AMP levels. Ghrelin activated Erk within 2min, then activated Akt and STAT3. Erk phosphorylation was inhibited by the calcium inhibitor cyclopiazonic acid (CPA). Ghrelin alone did not stimulate FRTL-5 cell proliferation but enhanced the effects of thyroid stimulating hormone (TSH). Pretreatment with TSH potentiates the growth effects of ghrelin in thyroid cells, and p66Shc, a growth factor receptor adaptor protein, might mediate these synergistic effects. Ghrelin phosphorylated TSH-induced p66Shc, which was inhibited by CPA. Ghrelin did not affect the proliferation of ARO cells, which showed no increased expression of p66Shc after TSH treatment. Thus, ghrelin-induced intracellular calcium signaling enhanced the TSH-induced proliferation of thyrocytes, possibly mediated by the p66Shc pathway.

Improved RNA quality and TaqMan Pre-amplification method (PreAmp) to enhance expression analysis from formalin fixed paraffin embedded (FFPE) materials

Background

Archival formalin-fixed paraffin-embedded (FFPE) tissues represent an abundant source of clinical specimens; however their use is limited in applications involving analysis of gene expression due to RNA degradation and modification during fixation and processing. This study improved the quality of RNA extracted from FFPE by introducing a heating step into the selected extraction protocols. Further, it evaluated a novel pre-amplification system (PreAmp) designed to enhance expression analysis from tissue samples using assays with a range of amplicon size (62–164 bp).

Results

Results from the Bioanalyzer and TaqMan^® data showed improvement of RNA quality extracted using the modified protocols from FFPE. Incubation at 70°C for 20 minutes was determined to be the best condition of those tested to disrupt cross-links while not compromising RNA integrity. TaqMan^® detection was influenced by master mix, amplicon size and the incorporation of a pre-amplification step. TaqMan^® PreAmp consistently achieved decreased C_T values in both snap frozen and FFPE aliquots compared with no pre-amplification.

Conclusion

Modification to extraction protocols has facilitated procurement of RNA that may be successfully amplified using QRT-PCR. TaqMan^® PreAmp system is a robust and practical solution to limited quantities of RNA from FFPE extracts.

BRAF mutation in papillary thyroid cancer: pathogenic role, molecular bases, and clinical implications

In recent years, the T1799A B-type Raf kinase (BRAF) mutation in thyroid cancer has received enthusiastic investigation, and significant progress has been made toward understanding its tumorigenic role and clinical significance. Among various thyroid tumors, this mutation occurs uniquely in papillary thyroid cancer (PTC), the most common endocrine malignancy, and some apparently PTC-derived anaplastic thyroid cancers. Many studies have found this mutation to be associated with those clinicopathological characteristics of PTC that are conventionally known to predict tumor progression and recurrence, including, for example, old patient age, extrathyroidal invasion, lymph node metastasis, and advanced tumor stages. Direct association of BRAF mutation with the clinical progression, recurrence, and treatment failure of PTC has also been demonstrated. The BRAF mutation has even been correlated with PTC recurrence in patients with conventionally low-risk clinicopathological factors. Some molecular mechanisms determining BRAF mutation-promoted progression and the aggressiveness of PTC have recently been uncovered. These include the down-regulation of major tumor suppressor genes and thyroid iodide-metabolizing genes and the up-regulation of cancer-promoting molecules, such as vascular endothelial growth factor, matrix metalloproteinases, nuclear transcription factor kappaB, and c-Met. Thus, BRAF mutation represents a novel indicator of the progression and aggressiveness of PTC. Significant advances have also occurred in the preclinical testing of new therapeutic strategies targeting the MAPK pathway aberrantly activated by BRAF mutation and other related mutations. New mitogen extracellular kinase (MEK) inhibitors developed recently are particularly promising therapeutic agents for thyroid cancer. With these advances, it has become clearer that BRAF mutation will likely have significant impact on the clinical management of PTC.

Global gene expression profiling of formalin-fixed paraffin-embedded tumor samples: a comparison to snap-frozen material using oligonucleotide microarrays

Oligonucleotide microarrays are widely used to investigate gene expression in a large-scale approach. A major limitation is the dependency on frozen material to obtain high-quality ribonucleic acid because most clinical specimens are formalin-fixed and paraffin-embedded (FFPE). The ability to analyze these samples using microarrays would enlarge the investigable sample stocks manifold. We conducted a comparison of snap-frozen and FFPE tissues investigating two malignomas. Gene expression profiles were obtained from both materials of the tumors. Independently processed triplicates of snap-frozen and FFPE specimen, respectively, were two-round-amplified and hybridized on Affymetrix GeneChips (Palo Alto, CA, USA). Differentially expressed genes were identified in both FFPE and frozen material. All replicates had a correlation coefficient (R) of greater than 0.95 after normalization. Only direct comparison of FFPE to frozen replicates resulted in a mean R of 0.86, rendering a "mixed" investigation unfeasible. More than 50% (419 genes) of the more than fivefold differentially expressed genes (800 in FFPE, 685 in frozen material) were detected concomitantly regardless of the material used, which is similar to other comparisons of different gene expression analysis platforms. Thus, global gene expression analyses using solely FFPE material seem to be feasible with nearly comparable results to frozen tissue studies.

Expression microarray analysis of papillary thyroid carcinoma and benign thyroid tissue: emphasis on the follicular variant and potential markers of malignancy

The most common sub-variant of papillary thyroid carcinoma (PTC) is the so-called follicular variant (FVPTC), which is a particularly problematic lesion and can be challenging from a diagnostic viewpoint even in resected lesions. Although fine needle aspiration cytology is very useful in the diagnosis of PTC, its accuracy and utility would be greatly facilitated by the development of specific markers for PTC and its common variants. We used the recently developed Applied Biosystems 1700 microarray system to interrogate a series of 11 benign thyroid lesions and conditions and 14 samples of PTC (six with classic morphology and eight with follicular variant morphology). TaqMan(R) reverse transcriptase-polymerase chain reaction was used to validate the expression portfolios of 50 selected transcripts. Our data corroborates potential biomarkers previously identified in the literature, such as LGALS3, S100A11, LYN, BAX, and cluster of differentiation 44 (CD44). However, we have also identified numerous transcripts never previously implicated in thyroid carcinogenesis, and many of which are not represented on other microarray platforms. Diminished expression of metallothioneins featured strongly among these and suggests a possible role for this family as tumour suppressors in PTC. Fifteen transcripts were significantly associated with FVPTC morphology. Surprisingly, these genes were associated with an extremely narrow repertoire of functions, including the major histocompatibility complex and cathepsin families.

Gene methylation in thyroid tumorigenesis

Aberrant gene methylation plays an important role in human tumorigenesis, including thyroid tumorigenesis. Many tumor suppressor genes are aberrantly methylated in thyroid cancer, and some even in benign thyroid tumors, suggesting a role of this epigenetic event in early thyroid tumorigenesis. Methylation of some of these genes tends to occur in certain types of thyroid cancer and is related to specific signaling pathways. For example, methylation of PTEN and RASSF1A genes occurs mostly in follicular thyroid cancer, and its tumorigenic role may be related to the phosphatidylinositol 3-kinase/Akt signaling pathway, whereas methylation of genes for tissue inhibitor of metalloproteinase-3, SLC5A8, and death-associated protein kinase occurs in papillary thyroid cancer and is related to the BRAF/MAPK kinase/MAPK pathway. Methylation of thyroid-specific genes, such as those for sodium/iodide symporter and thyroid-stimulating hormone receptor, is also common in thyroid cancer. Although its tumorigenic role is not clear, methylation, and hence silencing, of these thyroid-specific genes is a cause for the failure of clinical radioiodine treatment of thyroid cancer. Unlike gene methylation, histone modifications have been relatively poorly investigated in thyroid tumors. Future studies need to emphasize the mechanistic aspects of these two types of epigenetic alterations to uncover new molecular mechanisms in thyroid tumorigenesis and to provide novel therapeutic targets for thyroid cancer.

Thyroid-stimulating hormone receptor messenger ribonucleic acid measurement in blood as a marker for circulating thyroid cancer cells and its role in the preoperative diagnosis of thyroid cancer

CONTEXT

Thyroid cancer cells express TSH receptor (TSHR) mRNA, and its measurement in the circulation may be useful in the diagnosis/management of differentiated thyroid cancer (DTC).

OBJECTIVE

Our objective was to assess the diagnostic value of circulating TSHR mRNA for preoperative detection of DTC in patients with thyroid nodules.

PATIENTS

We measured TSHR mRNA levels by RT-PCR in 258 subjects: 51 healthy subjects and 207 patients (thyroid nodules, n = 180; recurrent thyroid cancer, n = 27) with fine-needle aspirations (FNA) and/or thyroid/neck surgery. Eighty-nine patients also had d-1 postoperative levels assessed.

OUTCOME MEASURES

TSHR mRNA levels were compared with FNA cytology for cancer detection preoperatively and serum thyroglobulin and/or whole-body 131I scans postoperatively.

RESULTS

Based on cytology/pathology, 88 patients had DTC and 119 had benign thyroid disease. The TSHR mRNA levels in cancer patients were significantly higher than in benign disease (P < 0.0001). At a cutoff value of 1.02 ng/microg total RNA, the TSHR mRNA correctly classified 78.7% of patients preoperatively (sensitivity = 72.0%; specificity = 82.5%). Of 131 patients with FNA and surgery, 51 were FNA positive (all cancer), 17 were FNA negative (15 benign, two cancer), and 63 were indeterminate. TSHR mRNA correctly diagnosed DTC in 16 of 24 (67%) and benign disease in 29 of 39 (74%) patients with indeterminate FNA (combined sensitivity = 90%; specificity = 80%). Combining TSHR mRNA and ultrasound features for follicular lesions correctly classified all follicular cancers and could have spared surgery in 31% of these patients with benign disease. TSHR mRNA has a short life in circulation, and normalized levels on postoperative d 1 correlated with disease-free status, whereas elevated levels predicted residual/metastatic disease.

CONCLUSIONS

TSHR mRNA measured with FNA enhances the preoperative detection of cancer in patients with thyroid nodules, reducing unnecessary surgeries, and immediate postoperative levels can predict residual/metastatic disease.

Molecular classification and biomarker discovery in papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy, with an incidence of approximately 22,000 cases in 2004 in the USA. Incidence is increasing, with a global estimate of half a million new cases this year. PTC is found in a variety of morphologic variants, usually grows slowly and is clinically indolent, although rare, aggressive forms with local invasion or distant metastases can occur. In recent years, thyroid cancer has been at the forefront of molecular pathology as a result of the consequences of the Chernobyl disaster and the recognition of the role of Ret/PTC rearrangements in PTC. Nonetheless, the molecular pathogenesis of this disease remains poorly characterized. In the clinical setting, benign thyroid nodules are far more frequent, and distinguishing between them and malignant nodules is a common diagnostic problem. It is estimated that 5-10% of people will develop a clinically significant thyroid nodule during their lifetime. Although the introduction of fine-needle aspiration has made PTC identification more reliable, clinicians often have to make decisions regarding patient care on the basis of equivocal information. Thus, the existing diagnostic tools available to distinguish benign from malignant neoplasms are not always reliable. This article will critically evaluate recently described putative biomarkers and their potential future role for diagnostic purposes in fine-needle aspiration cytology samples. It will highlight the evolution of our understanding of the molecular biology of PTC, from a narrow focus on specific molecular lesions such as Ret/PTC rearrangements to a pan-genomic approach.

Real-time quantitative RT-PCR shows variable, assay-dependent sensitivity to formalin fixation: implications for direct comparison of transcript levels in paraffin-embedded tissues

Real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) is a versatile tool for precise quantification of gene expression. Formalin-fixed and paraffin-embedded (FFPE) tissue is well suited for qRT-PCR, if RNA extraction is optimized and small amplicon sizes are used. However, little is known whether individual assays may show variable sensitivity to fixation. This is of great importance, if a direct comparison of different transcripts is performed within the same sample, such as for mRNA splice variants. We established a cell culture model to test for and quantify differences in performance of individual qRT-PCR assays on FFPE as compared with fresh material, using TaqMan methodology. RNA was isolated from 7 different cell lines either directly or after preparation of a FFPE cell block. RNA from both sources was reverse transcribed and gene expression quantified using 13 different TaqMan assays. All assays allowed highly reproducible target quantification, using both fresh and FFPE-derived cDNA. The 13 assays showed an average Ct difference of 3.2 between fresh and FFPE cells, if identical amounts of cDNA were used as template. However, the Ct shifts varied from 1.8 to 5.1 for individual assays, indicating variable resistance to fixation. These Ct shift differences were statistically highly significant in 27/78 (35%) of all possible combinations of assays. Because the Ct shift remained constant for each assay, they could be used for calculation of correction factors which rendered FFPE-derived expression data highly comparable to those obtained from fresh material, and as a consequence among each other. Thus, a standardized assessment of qRT-PCR assay efficiencies in FFPE allows for precise intraindividual comparison of mRNA species, such as splice variants with different biologic functions, in archival tissues.

PIK3CA and TFRC Located in 3q Are New Prognostic Factors in Esophageal Squamous Cell Carcinoma

BACKGROUND

Amplification of the chromosome 3q seems to occur frequently in esophageal squamous cell carcinoma (ESCC). This study analyzed the clinical effect of messenger RNA (mRNA) expression for PIK3CA (the gene that encodes phosphatidylinositol-3 kinase catalytic alpha-polypeptide) and TFRC (the gene that encodes the transferrin receptor), which map within chromosome 3q in ESCC.

METHODS

Formalin-fixed, paraffin-embedded ESCC tissues were examined. Total RNAs were extracted, and reverse transcription products were subjected to polymerase chain reaction amplification of beta-actin, PIK3CA, and TFRC.

RESULTS

Expression of beta-actin mRNA was detected in 67 (55.8%) of 120 samples, with PIK3CA mRNA expression in 22 (32.8%) of these 67 samples and TFRC mRNA expression in 15 (22.4%) of the 67 samples. PIK3CA mRNA expression correlated with regional lymph node metastasis (P = .04). TFRC mRNA expression correlated with distant metastasis (P = .04). Patients with positive results for either PIK3CA or TFRC mRNA displayed a significantly worse prognosis than patients with negative results (PIK3CA, P = .045; TFRC, P = .009). TFRC mRNA expression represented an independent prognostic factor in multivariate analysis (P = .0233), but PIK3CA did not (P = .7585).

CONCLUSIONS

PIK3CA and TFRC mRNA represent prognostic factors in patients with ESCC. TFRC mRNA offers an independent prognostic factor, and expression may have clinically important implications.

A systems approach to clinical oncology: focus on breast cancer

During the past decade, genomic microarrays have been applied with some success to the molecular profiling of breast tumours, which has resulted in a much more detailed classification scheme as well as in the identification of potential gene signature sets. These gene sets have been applied to both the prognosis and prediction of outcome to treatment and have performed better than the current clinical criteria. One of the main limitations of microarray analysis, however, is that frozen tumour samples are required for the assay. This imposes severe limitations on access to samples and precludes large scale validation studies from being conducted. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), on the other hand, can be used with degraded RNAs derived from formalin-fixed paraffin-embedded (FFPE) tumour samples, the most important and abundant source of clinical material available. More recently, the novel DASL (cDNA-mediated Annealing, Selection, extension and Ligation) assay has been developed as a high throughput gene expression profiling system specifically designed for use with FFPE tumour tissue samples.However, we do not believe that genomics is adequate as a sole prognostic and predictive platform in breast cancer. The key proteins driving oncogenesis, for example, can undergo post-translational modifications; moreover, if we are ever to move individualization of therapy into the practical world of blood-based assays, serum proteomics becomes critical. Proteomic platforms, including tissue micro-arrays (TMA) and protein chip arrays, in conjunction with surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF/MS), have been the technologies most widely applied to the characterization of tumours and serum from breast cancer patients, with still limited but encouraging results. This review will focus on these genomic and proteomic platforms, with an emphasis placed on the utilization of FFPE tumour tissue samples and serum, as they have been applied to the study of breast cancer for the discovery of gene signatures and biomarkers for the early diagnosis, prognosis and prediction of treatment outcome. The ultimate goal is to be able to apply a systems biology approach to the information gleaned from the combination of these techniques in order to select the best treatment strategy, monitor its effectiveness and make changes as rapidly as possible where needed to achieve the optimal therapeutic results for the patient.

Antitumor effects of etodolac, a selective cyclooxygenase-II inhibitor, against human prostate cancer cell lines in vitro and in vivo

OBJECTIVES

To investigate the effects of the selective cyclooxygenase-2 (COX-2) inhibitor etodolac on prostate cancer cell lines in vitro and in vivo and on E-cadherin expression in prostate cancer cells.

METHODS

We evaluated the cytotoxicity of etodolac on the three prostate cancer cell lines LNCaP, C4-2, and PC-3. We also performed quantitative real-time polymerase chain reaction to measure the mRNA expression of COX-2, Bcl-2, and E-cadherin in these cell lines after etodolac treatment. In addition, we investigated the in vivo antitumor effects of etodolac on a human prostate cancer xenograft model.

RESULTS

Etodolac exhibited significant antitumor effect in vivo and in vitro. The cytotoxicity of etodolac in LNCaP and C4-2 was markedly increased at a dose of 1000 nM in a time-dependent and dose-dependent manner. In the in vivo tumor growth study, the etodolac-treated mice exhibited more significant cytotoxicity than the phosphate-buffered saline-treated mice. Expression of E-cadherin after etodolac treatment tended to increase and that of Bcl-2 to decrease, but the expression of COX-2 had no definite tendency.

CONCLUSIONS

The COX-2 inhibitor etodolac exhibited an antitumor effect on prostate cancer cell lines in vitro and in vivo, and it might be useful for the treatment of hormone-resistant prostate cancer.

Reliable gene expression measurements from degraded RNA by quantitative real-time PCR depend on short amplicons and a proper normalization

Quantitative reverse transcriptase real-time PCR (QRT-PCR) is a robust method to quantitate RNA abundance. The procedure is highly sensitive and reproducible as long as the initial RNA is intact. However, breaks in the RNA due to chemical or enzymatic cleavage may reduce the number of RNA molecules that contain intact amplicons. As a consequence, the number of molecules available for amplification decreases. We determined the relation between RNA fragmentation and threshold values (Ct values) in subsequent QRT-PCR for four genes in an experimental model of intact and partially hydrolyzed RNA derived from a cell line and we describe the relation between RNA integrity, amplicon size and Ct values in this biologically homogenous system. We demonstrate that degradation-related shifts of Ct values can be compensated by calculating delta Ct values between test genes and the mean values of several control genes. These delta Ct values are less sensitive to fragmentation of the RNA and are unaffected by varying amounts of input RNA. The feasibility of the procedure was demonstrated by comparing Ct values from a larger panel of genes in intact and in partially degraded RNA. We compared Ct values from intact RNA derived from well-preserved tumor material and from fragmented RNA derived from formalin-fixed, paraffin-embedded (FFPE) samples of the same tumors. We demonstrate that the relative abundance of gene expression can be based on FFPE material even when the amount of RNA in the sample and the extent of fragmentation are not known.

ret/PTC and BRAF act as distinct molecular, time-dependant triggers in a sporadic Irish cohort of papillary thyroid carcinoma

The purpose of this study was to assess BRAF mutation rates in various thyroid tissues and to investigate if concomitant mutations with ret/PTC activation occurred in inflammatory and neoplastic lesions. To this end, we developed a novel Taqman based screening assay for the common T1799A BRAF mutation. Heterozygous T1799A mutations were detected in 13 of 34 (44%) papillary thyroid carcinomas (PTCs) tested. No such mutations were detected in the other tissue types tested. Concomitant presence of both oncogenes was reported in 5 of the 34 PTCs. A significant temporal trend was observed, with ret/PTC chimera detected for the most part before 1997 and BRAF mutations being more prevalent after 1997. The results suggest that some environmental/etiological agent(s) may have influenced the pathobiology of thyroid tumor development, among the population examined, over time.

Recent advances in the molecular diagnosis of diffuse large B-cell lymphoma

The field of molecular diagnostics is changing and adapting to new information obtained from genetic, genomic and proteomic profiling of diseases. One of the novel technologies that has made significant impact on the molecular diagnosis of lymphoid malignancies is DNA microarray technology. It has allowed the profiling of the most common types of lymphomas, identifying distinct molecular signatures of these diseases as well as novel subtypes that cannot otherwise be identified by conventional methods. In addition, it has also allowed the construction of molecularly defined prognostic models for various types of lymphomas and to better understand the molecular mechanisms that determine the behavior of the tumor. In this review, recent advances in the molecular diagnosis of diffuse large B-cell lymphoma are highlighted, using examples of how gene expression profiling has been used in disease classification and outcome predictions. The future development of this field and its applications in the clinical arena will also be discussed.

Effect of formalin on extraction of mRNA from a formalin-fixed sample: a basic investigation

BACKGROUND

The validity of molecular studies using RNA extracted from decades-old formalin-fixed and embedded tissue blocks is well documented. Formalin-fixed samples are, however, known to be poor materials for molecular biological applications. The aim of this study was to investigate the effect of formalin as a preservation agent on RNA quality and relevant molecular applications.

METHODS

The quantity and quality of RNA from liver tissues are modified by the fixation time. Rat liver tissues were harvested and fixed for 4, 8, 12, and 24 h in 10% buffer formalin, and only 9% of RNA could be extracted from the formalin-fixed tissue stored for 4 h.

RESULTS

Agarose gel electrophoresis did not show the characteristic pattern of RNA with 18S and 28S in all lanes. Based on the results, it is thought that the RNA was damaged owing to one or more of the following reasons: 1) formalin directly degrades RNA, 2) formalin inactivates RNase, and/or 3) formalin destroys the reagent for extraction of RNA. In this study, it was shown by electrophoresis that very little RNA was extracted by Trizol with 1% formalin.

CONCLUSIONS

Formalin has direct and indirect ill effects on RNA during the extraction process.

Measurement of gene expression in archival paraffin-embedded tissues: development and performance of a 92-gene reverse transcriptase-polymerase chain reaction assay

Throughout the last decade many laboratories have shown that mRNA levels in formalin-fixed and paraffin-embedded (FPE) tissue specimens can be quantified by reverse transcriptase-polymerase chain reaction (RT-PCR) techniques despite the extensive RNA fragmentation that occurs in tissues so preserved. We have developed RT-PCR methods that are sensitive, precise, and that have multianalyte capability for potential wide use in clinical research and diagnostic assays. Here it is shown that the extent of fragmentation of extracted FPE tissue RNA significantly increases with archive storage time. Probe and primer sets for RT-PCR assays based on amplicons that are both short and homogeneous in length enable effective reference gene-based data normalization for cross comparison of specimens that differ substantially in age. A 48-gene assay used to compare gene expression profiles from the same breast cancer tissue that had been either frozen or FPE showed very similar profiles after reference gene-based normalization. A 92-gene assay, using RNA extracted from three 10- micro m FPE sections of archival breast cancer specimens (dating from 1985 to 2001) yielded analyzable data for these genes in all 62 tested specimens. The results were substantially concordant when estrogen receptor, progesterone receptor, and HER2 receptor status determined by RT-PCR was compared with immunohistochemistry assays for these receptors. Furthermore, the results highlight the advantages of RT-PCR over immunohistochemistry with respect to quantitation and dynamic range. These findings support the development of RT-PCR analysis of FPE tissue RNA as a platform for multianalyte clinical diagnostic tests.

Real-time analysis of beta- and gamma-catenin mRNA expression in ret/PTC-1 activated and nonactivated thyroid tissues

Our group has previously demonstrated an association between ret/PTC-1 activation and decreased E-cadherin mRNA levels in papillary thyroid carcinoma. We also observed similarities in the E-cadherin expression profiles of Hashimoto thyroiditis and ret/PTC-1-positive papillary thyroid carcinomas and have hypothesized that ret/PTC-1 activation might cause not only the structural and nuclear peculiarities of PTC but also an immune reaction to thyroid epithelium. The objective of this study was to examine the expression of E-cadherin's ligands, beta- and gamma-catenin, in various thyroid tissue types in the context of ret/PTC-1 positivity using laser capture microdissection and TaqMan (Applied Biosystems, Foster City, CA). One-Step RT-PCR. Beta-catenin mRNA levels were found to be consistently decreased in both papillary and anaplastic carcinomas when compared with a normal/follicular adenoma group. A significant difference in expression levels was observed between papillary and follicular thyroid carcinomas with the latter having elevated mRNA levels of beta-catenin. Gamma-catenin mRNA was decreased in anaplastic carcinomas compared with normal/follicular adenoma groups. A similar expression profile of gamma-catenin as beta-catenin was observed in papillary and follicular carcinomas with the latter once again having higher mRNA levels. These results therefore suggest that although beta- and gamma-catenin may play a role in the progression of thyroid cancer in general, they do not appear to be associated with ret/PTC-1-modulated pathways.

Effects of thyroid hormone suppression therapy on adverse clinical outcomes in thyroid cancer

BACKGROUND

Long-term thyroid hormone (TH) therapy aiming at the suppression of serum thyrotropin (TSH) has been traditionally used in the management of well differentiated thyroid cancer (ThyrCa). However, formal validation of the effects of thyroid hormone suppression therapy (THST) through randomized controlled trials is lacking. Additionally, the role - if any - of TSH effect at low ambient concentrations upon human thyroid tumorigenesis remains unclear.

AIM

Evaluation of the effect of THST on the clinical outcomes of papillary and/or follicular ThyrCa.

METHODS

By using a quantitative research synthesis approach in a cumulative ThyrCa cohort, we evaluated the effect of THST on the likelihood of major adverse clinical events (disease progression/recurrence and death). A total of 28 clinical trials published during the period 1934-2001 were identified; only 10 were amenable to meta-analysis. Causality was assessed by Hill criteria.

RESULTS

Out of 4, 174 patients with ThyrCa, 2, 880 (69%) were reported as being on THST. Meta-analysis showed that the group of patients who received THST had a decreased risk of major adverse clinical events (RR = 0.73; Cl = 0.60-0.88; P < 0.05). Further, by applying a Likert scale, 15/17 interpretable studies showed either a 'likely' or 'questionable' beneficial effect of THST. Assessment of causality between TSHT and reduction of major adverse clinical events suggested a probable association.

CONCLUSIONS

THST appears justified in ThyrCa patients following initial therapy. As most primary studies were imperfect, future research will better define the effect of THST upon ThyrCa clinical outcomes.

Real-time quantitative analysis of E-cadherin expression in ret/PTC-1-activated thyroid neoplasms

Papillary thyroid carcinoma (PTC), the most common variety of thyroid cancer, is found in a variety of morphologic variants, usually grows slowly, and is clinically indolent, although rare, aggressive forms, with local invasion or distant metastases, occur. Our group has previously demonstrated an association between Hashimoto thyroiditis and ret/PTC-1 activation, and have hypothesised that c-ret activation might be implicated in immune reaction to thyroid epithelium. The objective of this study was to examine expression of the cellular adhesion molecule, E-cadherin, in various thyroid tumor types and Hashimoto thyroiditis in the context of ret/PTC-1 positivity by using laser capture microdissection and TaqMan reverse transcription-polymerase chain reaction (RT-PCR). Variable down-regulation of E-cadherin among carcinomas was demonstrated, with anaplastic carcinomas showing little or no expression. Follicular thyroid carcinomas consistently had significantly decreased E-cadherin expression compared with papillary thyroid carcinomas. The ret/PTC-1-positive papillary thyroid carcinoma (PTCret+) and Hashimoto thyroiditis cases had consistently lower E-cadherin expression levels than the corresponding ret/PTC-1-negative papillary carcinomas (PTCret-), suggesting not only an association between ret activation and the loss of cellular adhesion but also, more significantly, an association between papillary thyroid carcinoma and Hashimoto thyroiditis.

Quantitative molecular analysis of laser-microdissected paraffin-embedded human tissues

Laser microdissection enables the contamination-free isolation of morphologically defined pure cell populations from archival formalin-fixed paraffin-embedded tissue specimens. Cells isolated by this method have been characterized by a wide variety of qualitative molecular assays, e.g. loss of heterozygosity, point mutations, clonality and lineage origin. The recently introduced real-time PCR technology renders the reliable quantification of very small amounts of nucleic acids possible. Several groups including our own showed that this technique can be successfully applied for the quantification of DNA and RNA isolated from microdissected archival tissue sections, even after immunohistochemical staining. The exact analysis of quantitative changes of nucleic acids during the course of pathological alterations has thus become possible. In many situations these quantitative changes can be expected to be more important than qualitative changes. The new technology for the quantification of structural genomic alterations and changes in the gene expression pattern in conjunction with microdissection have equipped morphologists with a powerful tool to study reactive and neoplastic changes of tissues.

Cytokine induction as a measure of cutaneous toxicity in primary and immortalized porcine keratinocytes exposed to jet fuels, and their relationship to normal human epidermal keratinocytes

The purpose of this study was to identify biomarkers of toxicity in primary porcine keratinocytes (PKC) and an immortalized porcine keratinocyte cell line (MSK3877) exposed to jet fuels Jet A, JP-8, and JP-8+100. Cells were exposed to 0.1% jet fuels and assayed for interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-alpha) mRNA using the TaqMan real time quantitative reverse transcriptase PCR assay. IL-8 and TNF-alpha protein release was measured using an ELISA. PKC exposed to jet fuels caused a slight upregulation of TNF-alpha mRNA at early time points, but no significant differences in TNF-alpha protein production were detected. IL-8 mRNA was increased at 4 h following exposure, and IL-8 protein was increased at 8 h. In MSK 3877 cells, jet fuels were shown to increase the production and expression of TNF-alpha mRNA and protein at 30 min and 1 h following exposure, respectively. IL-8 mRNA was only slightly induced compared to control. IL-8 protein release was suppressed by jet fuel exposure. These results were compared with those of a previous study in our laboratory to evaluate the utility of using porcine cells in lieu of normal human epidermal keratinocytes (NHEK). Similarities exist between PKC and NHEK with respect to both TNF-alpha and IL-8 production. The expression profile of TNF-alpha in MSK3877 cells mimics that of NHEK. In contrast, the profile of IL-8 expression opposes that of PKC and NHEK. These results suggest that porcine keratinocytes are susceptible to jet fuel toxicity. However, the responses of immortalized cells may vary from those of PKC and NHEK necessitating cautious interpretation of such data.

Assessment of ret/PTC-1 rearrangements in neoplastic thyroid tissue using TaqMan RT-PCR

Among oncogenes studied in thyroid cancers, a specific activated form of c-ret has been found in a minority of papillary thyroid carcinomas (PTCs). In these tumours, c-ret is activated when by somatic rearrangements, the intracellular domain of RET is juxtaposed with the amino-terminal portion of a different donor gene such as H4, thereby generating a chimeric transcript (ret/PTC-1). The functional effects of c-ret activation and its prognostic implications are currently unclear. This study was undertaken to assess the frequency of RET/PTC-1 expression, any distinctive features of positive tumours to which it might be related, and its prognostic importance. Archival material from 88 thyroid neoplasms [50 PTCs, eight anaplastic carcinomas (ATCs), 25 follicular thyroid carcinomas (FTCs) and five follicular adenomas (FAs)] were analysed for ret/PTC-1 and H4 expression using 5' nuclease assay (TaqMan RT-PCR). RNA from the TPC-1 cell line was included as a positive control for c-ret activation. No FTC or FA displayed activation of ret/PTC-1, though all expressed H4. c-ret activation was found in 24% of PTCs (12 of 50), in 87.5% of ATCs (7 of 8), and in 33% of the combined PTC/ATC group. The frequency of c-ret activation in the aggressive ATC variants noted here suggests that ret/PTC-1-positive PTCs might also have a similar poor prognosis and a follow-up study on this cohort is in progress. Ninety per cent of ret/PTC-1-positive tumours failed to express H4, a phenomenon that has not been described previously and which may have considerable bearing on tumour morphology. A statistically significant proportion (58%) of ret/PTC-1-positive, H4-negative PTCs was associated with chronic inflammatory cell infiltration of the tumour and/or the surrounding thyroid. This association has not been reported previously.

ret/PTC-1 Activation in Hashimoto Thyroiditis

Activation of ret/PTC-1 has been documented in a minority of papillary thyroid carcinomas (PTC). In a recent study, the authors' group detected the presence of ret/PTC-1 in association with a background of florid lymphocytic thyroiditis (LT) in 58% of cases of PTC studied, which prompted them to examine the incidence of RET/PTC-1 expression in 27 examples of various forms of nonlymphomatous lymphoid infiltration of the thyroid by using TaqMan RT-PCR. Overall, 21 cases (78%) were found to express the chimeric transcript of ret/PTC-1. Eighteen cases of Hashimoto thyroiditis were positive (95%), and, of these, three had concomitant PTC while the remainder had no histologic evidence of associated malignancy. Three cases of lymphocytic thyroiditis demonstrated activated ret/PTC-1 (43%), two having associated PTC. These data suggest either that ret/PTC-1 is an indicator of follicular thyroid cell activation or that ret/PTC-1 activation is an early event in malignant transformation. If the latter is the case, it may be that, in a defined subset of the cell population, ret/PTC-1 activation elicits an autoimmune response, which, while possibly curtailing the development of PTC in the majority of cases, results in destruction of the thyroid parenchyma. Int J Surg Pathol 8(3):185-189, 2000