Genome-wide profiling of papillary thyroid cancer identifies MUC1 as an independent prognostic marker

Distinct genetic changes characterise multifocality and diverse histological subtypes in papillary thyroid carcinoma

AIMS

This study was undertaken to investigate the genetic factors underlying the development of multifocality and phenotypic diversity in multifocal papillary thyroid carcinoma (mPTC).

METHODS

Loss of heterozygosity (LOH) and BRAF(V600E) mutation status were analysed in a total of 55 individual tumour foci from 18 cases of mPTC. The genetic findings and morphology of tumour foci were then compared.

RESULTS

Multifocal PTC LOH rates were higher than observed previously in solitary PTC. Different patterns of LOH and BRAF(V600E) positivity separated follicular variant tumours and tumour foci from other PTC histological subtypes. In five cases, genetic alterations were detected in morphologically normal thyroid epithelium.

CONCLUSIONS

These findings support the concept that multifocal PTCs develop through clonal selection from a field of pre-neoplastic cells, with morphotype differentiation correlating with specific tumour-genetic alterations. The relatively high genetic disarray in multifocal PTC may underlie their ability to spread throughout the thyroid gland.

The spectrum of papillary thyroid carcinoma variants

Papillary thyroid carcinoma is the most common type of thyroid malignancy. The diagnostic features of these tumors include characteristic nuclear cytology. However, many variants have been reported with different morphology and molecular profiles. Although the vast majority of papillary thyroid carcinomas have an excellent prognosis, some variants of papillary thyroid carcinoma can have a more aggressive course. With this increased attention to papillary thyroid carcinoma variants has come the need to sort out which variants are clinically important and should be recognized by practicing pathologists. The main objectives of this review article are to (1) summarize the gross and histopathologic features of papillary thyroid carcinoma; (2) provide an overview of the subtypes of papillary thyroid carcinoma and their prognosis; (3) discuss established and emerging data on the immunohistochemical findings that are helpful in differential diagnosis; and (4) summarize molecular findings and pathogenesis of these lesions.

Muc-1 expression may help characterize thyroid nodules but does not predict patients' outcome

Our purpose was to evaluate MUC1 clinical utility in the diagnosis and prognosis of thyroid cancer patients. We studied the protein expression of MUC1 in 289 thyroid carcinomas and 121 noncancerous thyroid nodules. There were 41 follicular carcinomas (FC) and 248 papillary thyroid carcinomas (PTC) including 149 classic (CPTC), 20 tall cell (TCPTC) and 79 follicular variants (FVPTC). In addition, we used a quantitative real-time PCR (q-PCR) method to measure MUC1 mRNA expression levels in 108 carcinomas, 23 hyperplasias, and 19 FA. According to their serum Tg levels and other evidences of recurrence/metastasis, the patients were classified as free-of-disease (185 cases) or bad outcome (56 cases, 10 deaths). MUC1 protein was identified in 80.2% PTC; 48.8% FC; 68.3% FVPTC; 70% TCPTC; 21.8% FA; 30% hyperplasias and 6% normal thyroid tissues. MUC1 distinguished benign from malignant thyroid tissues (sensitivity = 89%; specificity = 53%). MUC1 also differentiated FC from FA (p = 0.0083). q-PCR mRNA expression of MUC1 also distinguished malignant from benign nodules (Mann-Whitney test, p < 0.0001). However, neither IHC nor mRNA MUC1 expression was associated with any clinical or pathological feature of aggressiveness or outcome. We suggest that MUC1 expression may help differentiate follicular patterned thyroid lesions.

Identification of several novel non-p.R132 IDH1 variants in thyroid carcinomas

CONTEXT

Somatic mutations at residue R132 of isocitrate dehydrogenase 1 (IDH1) were recently discovered in gliomas and leukaemia at a high frequency. IDH1 is a metabolic gene, and the R132 mutations create a new enzymatic activity.

OBJECTIVES

To determine whether IDH1 had somatically acquired mutations in thyroid carcinomas.

DESIGN

Exons 4 and 6 of IDH1 were sequenced in a large panel of thyroid tumours (n=138) and compared with the patients normal DNA (n=26). We also correlated IDH1 mutations with clinical-pathological data and BRAF and RAS mutational status.

RESULTS

We identified four novel and two previously described non-synonymous variants in thyroid carcinomas, which were absent in benign tumours and paired normal thyroid. Although IDH1 variants occurred at higher frequency in follicular thyroid carcinomas, follicular variant of papillary thyroid carcinoma (PTC) and undifferentiated thyroid carcinomas than the observed variants in classical PTC (15/72 vs 3/37), it was not significant (P=0.1). Sequence alignment across several species shows that all IDH1 genetic alterations occurred at evolutionarily conserved residues located within the active site, and therefore, are likely to affect protein function. Unlike other tumours, IDH1 and BRAF or RAS mutations are not mutually exclusive. There was no association between IDH1 mutational status and clinical characteristics.

CONCLUSION

IDH1-acquired genetic alterations are highly prevalent in thyroid carcinomas (16%). Our findings not only extend our understanding of the molecular mechanism underlying pathogenesis of thyroid tumours, but also emphasize the biological differences between tumour types. Those tumours with IDH1 mutations might benefit from therapies that exploit this alteration.

MUC1 oncogene amplification correlates with protein overexpression in invasive breast carcinoma cells

The MUC1 gene is aberrantly overexpressed in approximately 90% of human breast cancers. Several studies have shown that MUC1 overexpression is due to transcriptional regulatory events. However, the importance of gene amplification as a mechanism leading to the increase of MUC1 expression in breast cancer has been poorly characterized. The aim of this study was to evaluate the role of MUC1 gene amplification and protein expression in human breast cancer development. By means of real-time quantitative polymerase chain reaction and immunohistochemical methods, 83 breast tissue samples were analyzed for MUC1 gene amplification and protein expression. This analysis showed MUC1 genomic amplification and a positive association with the histopathological group in 12% (1 out of 8) of benign lesions and 38% (23 out of 60) of primary invasive breast carcinoma samples (P = 0.004). Array-comparative genomic hybridization meta-analysis of 886 primary invasive breast carcinomas obtained from 22 studies showed MUC1 genomic gain in 43.7% (387 out of 886) of the samples. Moreover, we identified a highly statistical significant association between MUC1 gene amplification and MUC1 protein expression assessed by immunohistochemistry and Western blot test (P < 0.0001). In conclusion, this study demonstrated that MUC1 copy number increases from normal breast tissue to primary invasive breast carcinomas in correlation with MUC1 protein expression.

Copy number and gene expression alterations in radiation-induced papillary thyroid carcinoma from chernobyl pediatric patients

BACKGROUND

Following exposure to radiation during the Chernobyl fallout tragedy, papillary thyroid carcinoma (PTC) increased significantly in individuals who were children at the time of the accident. We have used two high-throughput, whole genome platforms to analyze radiation-induced PTCs from pediatric patients from the Chernobyl region.

METHODS

We performed comparative genomic hybridization using Affymetrix 50K Mapping arrays and gene expression profiling on 10 pediatric post-Chernobyl PTCs obtained from patients living in the region. We performed an overlay analysis of these two data sets.

RESULTS

Many regions of copy number alterations (CNAs) were detected including novel regions that had never been associated with PTCs. Increases in copy numbers were consistently found on chromosomes 1p, 5p, 9q, 12q, 13q, 16p, 21q, and 22q. Deletions were observed less frequently and were mapped to 1q, 6q, 9q, 10q, 13q, 14q, 21q, and 22q. Gene expression analysis revealed that most of the altered genes were also perturbed in sporadic adult PTC; however, 141 gene expression changes were found to be unique to the post-Chernobyl tumors. The genes with the highest increases in expression that were novel to the pediatric post-Chernobyl tumors were TESC, PDZRN4, TRAa/TRDa, GABBR2, and CA12. The genes showing the largest expression decreases included PAPSS2, PDLIM3, BEXI, ANK2, SORBS2, and PPARGCIA. An overlay analysis of the gene expression and CNA profiles was then performed. This analysis identified genes showing both CNAs and concurrent gene expression alterations. Many of these are commonly seen in sporadic PTC such as SERPINA, COL8A, and PDX, while others were unique to the radiation-induced profiles including CAMK2N1, AK1, DHRS3, and PDE9A.

CONCLUSIONS

This type of analysis allows an assessment of gene expression changes that are associated with a physical mechanism. These genes and chromosomal regions are potential markers for radiation-induced PTC.

Reactivity of a humanized antibody (hPankoMab) towards a tumor-related MUC1 epitope (TA-MUC1) with various human carcinomas

Humanized antibodies against tumor-related antigens are now established reagents for in vivo diagnostics and for therapeutic approaches, and are increasingly developed. Humanized PankoMab (hPankoMab), a humanized form of PankoMab directed against a novel tumor-related MUC1 epitope (TA-MUC1), was recently developed for clinical application. In the present study, the reactivity of hPankoMab with various human cancers was systematically studied by immunohistochemistry on 137 surgical specimens, including lung, breast, gastric, colorectal, liver, cervical, kidney, thyroid, and other carcinomas, as well as on several non-epithelial malignancies. The study was performed on paraffin sections without antigen retrieval. hPankoMab reacted strongly with carcinomas originating from glandular or squamous epithelia, weakly with hepatocellular carcinomas, and not with sarcomas. The binding sites of hPankoMab in carcinomas were found around the whole cell surface and, in most cases, also in the cytoplasm of cancer cells.

Papillary carcinoma tall cell variant (TCV): a review

Tall cell variant of papillary thyroid carcinoma is an aggressive form of thyroid cancer with a significant mortality. This review describes the pathology of this variant, compares it to its pathologic mimics and discusses its clinical pathologic features. The literature on this tumor is reviewed. A brief discussion of molecular pathologic correlates is included.

Tall-cell variant of papillary thyroid carcinoma: a matched-pair analysis of survival

BACKGROUND

The tall-cell variant (TCV) of papillary thyroid carcinoma (PTC) is considered a more aggressive variant of PTC, with a poor prognosis. This is largely due to the tendency for TCV to present at an older age and with extrathyroidal extension (ETE). When these two variables are controlled for, it is unclear whether tall-cell histology alone portends a poor prognosis. Because previous studies have been underpowered to adequately answer this question, we hypothesized that TCV may have poorer prognosis than PTC. Our objective was to utilize a large cancer registry to obtain sufficient power to differentiate between outcomes in cases of TCV and PTC.

METHODS

Using the National Cancer Institute's Surveillance, Epidemiology, and End Results database, we identified 278 TCV patients and 2522 classical PTC patients with sufficient information for a detailed matched-pair analysis. Each TCV patient was matched with a PTC patient for age, sex, extent of ETE, regional and distant metastases, surgical and adjuvant therapy, and year of diagnosis. The TCV cohort was then compared against all PTC cases and matched PTC cases.

RESULTS

Compared with classical PTC, TCV patients presented at an older age (54.3 years vs. 46.3 years, p < 0.0001) had a higher rate of ETE (53.6% vs. 30.2%, p < 0.0001) and poorer 5-year disease-specific survival (81.9% vs. 97.8%, p < 0.0001). In the matched-pair analysis comparing TCV patients to the matched PTC cohort, 5-year disease-specific survival was poorer in the TCV cohort (81.9% vs. 91.3%, p = 0.049). The number of deaths in the TCV cohort was higher than in the matched PTC cohort (p = 0.043).

CONCLUSIONS

TCV exhibits poorer survival than classical PTC. When the major prognostic factors for thyroid cancer are controlled for, including age and ETE, tall-cell histology alone remains a significant prognostic factor for disease-specific death.

Mucins in cancer: function, prognosis and therapy

Epithelia are protected from adverse conditions by a mucous barrier. The secreted and transmembrane mucins that constitute the mucous barrier are largely unrecognized as effectors of carcinogenesis. However, both types of mucins are intimately involved in inflammation and cancer. Moreover, diverse human malignancies overexpress transmembrane mucins to exploit their role in signalling cell growth and survival. Mucins have thus been identified as markers of adverse prognosis and as attractive therapeutic targets. Notably, the findings that certain transmembrane mucins induce transformation and promote tumour progression have provided the experimental basis for demonstrating that inhibitors of their function are effective as anti-tumour agents in preclinical models.

Molecular markers of aggressiveness of thyroid cancer

PURPOSE OF REVIEW

To review recent progress at defining molecular markers that predict the biological behavior of thyroid cancer.

RECENT FINDINGS

Thyroid cancer behavior is defined by the effects of the initiating oncogene as well as secondary events in tumor cells and the tumor microenvironment that are both genetic and epigenetic. Over the past several years, there has been intense focus on identifying molecular markers to better predict the aggressiveness of thyroid cancers and also to define therapeutic targets. The results of recent articles in this area of work are summarized with a focus of differentiated follicular-cell-derived forms of thyroid cancer.

SUMMARY

Clinical staging predicts tumor behavior in many cases, but does not allow true 'personalization' of initial therapy or identify potential therapeutic targets for patients with progressive disease that does not respond to standard therapies. Recent data point to several new opportunities to refine thyroid cancer treatment based on molecular information. Several highlighted articles have begun to apply this information with clinical intent.

Anaplastic thyroid cancer: molecular pathogenesis and emerging therapies

Anaplastic thyroid cancer (ATC) is a rare malignancy. While external beam radiation therapy has improved locoregional control, the median survival of approximately 4 months has not changed in more than half a century due to uncontrolled systemic metastases. The objective of this study was to review the literature in order to identify potential new strategies for treating this highly lethal cancer. PubMed searches were the principal source of articles reviewed. The molecular pathogenesis of ATC includes mutations in BRAF, RAS, catenin (cadherin-associated protein), beta 1, PIK3CA, TP53, AXIN1, PTEN, and APC genes, and chromosomal abnormalities are common. Several microarray studies have identified genes and pathways preferentially affected, and dysregulated microRNA profiles differ from differentiated thyroid cancers. Numerous proteins involving transcription factors, signaling pathways, mitosis, proliferation, cell cycle, apoptosis, adhesion, migration, epigenetics, and protein degradation are affected. A variety of agents have been successful in controlling ATC cell growth both in vitro and in nude mice xenografts. While many of these new compounds are in cancer clinical trials, there are few studies being conducted in ATC. With the recent increased knowledge of the many critical genes and proteins affected in ATC, and the extensive array of targeted therapies being developed for cancer patients, there are new opportunities to design clinical trials based upon tumor molecular profiling and preclinical studies of potentially synergistic combinatorial novel therapies.

Papillary thyroid carcinoma tall cell variant

BACKGROUND

The most common of the aggressive variant of papillary thyroid carcinoma (PTC) is the tall cell variant (TCV). Because there are serious prognostic and management implications to a diagnosis of TCV, we review the entity to inform clinicians about the many facets of TCV.

SUMMARY

The TCV of PTC is characterized by cells having the nuclear features of PTC and whose height is at least twice or thrice their width. There is disagreement regarding the proportion of tall cells and the cell height required to diagnose TCV. In view of its blurred definition and rarity, studies have shown that TCV is still underdiagnosed. We propose that PTC be diagnosed as TCV if it is composed of > or =50% tall cells. The latter should have a height that is at least twice their width, an eosinophilic cytoplasm, and the nuclear features of PTC. Whatever its definition, there is a consensus that TCV has a higher recurrence and death rate than classical PTC. Most authorities believe that TCV's worse prognosis is related to its older age at presentation, larger tumor size, and high frequency of extrathyroid extension (ETE). However, in a recent article, TCV without ETE was shown to have a more aggressive behavior than classical PTC without ETE independent of age, gender, and tumor size. The aggressive behavior of TCV could be related to the high expression of Muc1 and matrix metalloproteinase and to the higher prevalence of B-RAF mutations when compared to classical PTC. The importance of TCV is accentuated by the fact that it is overrepresented in those fluorodeoxyglucose positron-emission tomogram (FDG-PET)-positive thyroid carcinomas that are refractory to radioactive iodine (RAI) therapy constituting 20% of these incurable tumors.

CONCLUSION

TCV is a biologically and clinically aggressive form of PTC that is still underdiagnosed. TCV is overrepresented in patients with RAI refractory disease. It has a high prevalence of B-RAF mutations making the latter an attractive target in RAI refractory cases. Imaging modalities that can detect RAI refractory disease such as FDG-PET scanning are needed in many patients and a requirement in those with extensive ETE. More studies are needed to identify those TCV that become RAI refractory and develop effective target therapies against these incurable carcinomas.

Absence of allelic imbalance involving EMSY, CAPN5, and PAK1 genes in papillary thyroid carcinoma

Papillary thyroid cancer (PTC) accounts for 80% of all thyroid malignancies, and genetic alterations associated to its etiology remain largely unknown. Chromosomal band 11q13 seems to be one of the most frequently amplified regions in human cancer, providing several candidate genes that need detailed characterization. The aim of our study was to investigate the existence of allelic imbalance at EMSY, CAPN5, and PAK1, as candidate genes within 11q13.5-q14 region using a single nucleotide polymorphism-based analysis. We selected a panel of 9 polymorphisms that were analyzed in 41 thyroid carcinoma samples, their contralateral non-pathological tissue and 178 controls from the general population. We did not detect allelic imbalance at these loci in our series. However, we observed a difference in the EMSY-haplotype distribution among PTC patients when compared to controls (odds ratio=2.00; p=0.02). We conclude that 11q13.5-q14 is not imbalanced in PTC, but there is evidence suggesting that EMSY might be of relevance in PTC etiology.

Molecular classification of thyroid nodules by cytology

OBJECTIVES

Fine needle aspiration (FNA) biopsy of thyroid nodules provides cytologic specimens whose interpretation can direct patients toward either thyroidectomy or observation. Approximately 20% of FNA specimens yield an indeterminate result. Recent studies have characterized differences in gene expression between benign and malignant conditions, most often using whole tissue. Our goal was to determine the feasibility of quantitative polymerase chain reaction (qPCR)-based gene expression analysis in cytologic samples. For five genes shown to be over-expressed in thyroid carcinomas (fibronectin, galectin-3, Met/HGFR, MUC1, and GA733-precursor), we compared expression among pathologic states.

STUDY DESIGN

Prospective laboratory analysis of 20 thyroidectomy specimens.

METHODS

Routine microscopy was performed. Cytologic samples were obtained from the dominant nodules, and RNA was extracted. Preliminary analysis using fluorometry and reverse-transcriptase (RT)-PCR was performed. Expression levels of the test genes in nodules and from control samples were measured by real-time qPCR. Fold changes in gene expression were compared.

RESULTS

Only one specimen did not yield sufficient intact RNA for gene expression analysis. RT-PCR revealed satisfactory RNA recovery in all other specimens. qPCR showed significant over-expression of fibronectin in the papillary carcinomas compared with the goiters (P = .0013), follicular adenomas (P = .0014), and follicular carcinomas (P = .0001). Differences in both fibronectin and MUC1 expression between the follicular carcinomas and the follicular adenomas were also significant (P = .025 and .045, respectively).

CONCLUSIONS

Cytologic specimens were a satisfactory source of tissue for qPCR-based gene expression analysis. Both fibronectin and MUC1 were differentially expressed in follicular adenomas and follicular carcinomas, and fibronectin expression differed in papillary carcinomas compared with the other lesions. These results may form the basis of a clinical predictor for lesions with indeterminate or suspicious cytology.

Genome-wide studies in thyroid neoplasia

There is much interest in the application of genome biology to the field of thyroid neoplasia, despite the relatively low mortality rate associated with thyroid cancer in general. The principal reason for this interest is that the field of thyroid neoplasia stands to benefit from the application of genomic information to address a variety of pathologic and clinical issues. In addition to practical patient care issues, there is an excellent opportunity of expand the basic understanding of thyroid carcinogenesis. In this article, the most relevant genomic work on thyroid tumors performed to date is reviewed along with some general comments about the potential impact of genomic biology on thyroid pathology and the management of patients with thyroid nodules and cancer.

S100A4 expression is associated with lymph node metastasis in papillary microcarcinoma of the thyroid

The detection of papillary microcarcinomas of the thyroid is increasing due to frequent use of ultrasound and fine-needle aspiration biopsy. Although most of the papillary microcarcinomas remain quiescent and follow an indolent clinical course, some behave aggressively and metastasize early, giving rise to clinically significant disease. There have been few studies concerning factors predictive of lymph node metastasis in papillary microcarcinomas. We analyzed the expression of S100A4, cyclin D1, p27 and MUC1, the presence of the BRAF V600E mutation and the clinicopathological features of the tumors, including patient age, tumor size (>or=5 vs <5 mm), extrathyroidal extension, multifocality, histological subtype, sclerosis and encapsulation, in a series of 198 papillary microcarcinomas in relation to lymph node metastasis to determine the predictive factors of lymph node metastasis. On univariate analysis, tumor size of 5 mm or more, extrathyroidal extension, multifocality, sclerosis and the expression of S100A4 and cyclin D1 predicted lymph node metastasis, whereas patient age, expression of p27 and MUC1 and the BRAF V600E mutation did not. Moreover, tumor size 5 mm or more, multifocality and expression of S100A4, especially its strong expression in the invasive fronts, were significantly associated with macrometastasis and lateral node metastasis. On multivariate analysis, multifocality and expression of S100A4 were found to be common independent predictive factors of lymph node metastasis, macrometastases, and lateral node metastasis. In conclusion, S100A4 expression in papillary microcarcinomas may indicate the presence of nodal metastasis. Thus, S100A4 immunohistochemistry may be valuable for predicting metastatic potential in papillary microcarcinomas.

Clinicopathological correlations of Bcl-xL and Bax expression in differentiated thyroid carcinoma

OBJECTIVE

The Bcl-2 family proteins are essential mediators in the apoptotic process. Our aim was to investigate whether anti-apoptotic Bcl-xL and pro-apoptotic Bax were over-expressed in a large series of differentiated thyroid carcinomas (DTC) and to study their association with tumour presentation at diagnosis and prognosis.

DESIGN AND PATIENTS

We examined the immunohistochemical expression of Bcl-xL and Bax in benign nodular thyroid disease (BNTD) and DTC and their association with clinicopathological parameters. Thyroid tissue samples were collected from an unselected series of patients undergoing surgical resection for DTC (n = 74) or BNTD (n = 15).

RESULTS

Among DTC cases, expression of Bcl-xL was found to be high in 43.2% and low or absent in 56.8%. Expression of Bax was high in 75.7% and low or absent in 24.3%. Non-neoplastic thyroid tissue was largely unstained for both proteins. Among BNTD cases, expression of Bcl-xL was high in 13.3% and low or absent in 86.6%. Expression of Bax was high in 14.3% and low or absent in 86.6%. A significant association was found between Bcl-xL expression and the presence of high-risk histological subtype (P < 0.05), and regional lymph node (P < 0.01) and distant metastases (P < 0.01). The association between high Bcl-xL expression levels and a longer time of persistent disease after radioiodine ablation was also significant (P < 0.01). Bcl-xL expression was confirmed as an independent prognostic factor for persistent disease in DTC (relative risk, 2.5; 95% confidence interval, 1.1-5.9; P < 0.05).

CONCLUSIONS

Immunohistochemical expression of Bcl-xL might be a valuable tool in the prediction of tumour aggressiveness in DTC.

A multi-gene approach to differentiate papillary thyroid carcinoma from benign lesions: gene selection using support vector machines with bootstrapping

Selection of novel molecular markers is an important goal of cancer genomics studies. The aim of our analysis was to apply the multivariate bioinformatical tools to rank the genes - potential markers of papillary thyroid cancer (PTC) according to their diagnostic usefulness. We also assessed the accuracy of benign/malignant classification, based on gene expression profiling, for PTC. We analyzed a 180-array dataset (90 HG-U95A and 90 HG-U133A oligonucleotide arrays), which included a collection of 57 PTCs, 61 benign thyroid tumors, and 62 apparently normal tissues. Gene selection was carried out by the support vector machines method with bootstrapping, which allowed us 1) ranking the genes that were most important for classification quality and appeared most frequently in the classifiers (bootstrap-based feature ranking, BBFR); 2) ranking the samples, and thus detecting cases that were most difficult to classify (bootstrap-based outlier detection). The accuracy of PTC diagnosis was 98.5% for a 20-gene classifier, its 95% confidence interval (CI) was 95.9-100%, with the lower limit of CI exceeding 95% already for five genes. Only 5 of 180 samples (2.8%) were misclassified in more than 10% of bootstrap iterations. We specified 43 genes which are most suitable as molecular markers of PTC, among them some well-known PTC markers (MET, fibronectin 1, dipeptidylpeptidase 4, or adenosine A1 receptor) and potential new ones (UDP-galactose-4-epimerase, cadherin 16, gap junction protein 3, sushi, nidogen, and EGF-like domains 1, inhibitor of DNA binding 3, RUNX1, leiomodin 1, F-box protein 9, and tripartite motif-containing 58). The highest ranking gene, metallophosphoesterase domain-containing protein 2, achieved 96.7% of the maximum BBFR score.

Histological aggressiveness of fluorodeoxyglucose positron-emission tomogram (FDG-PET)-detected incidental thyroid carcinomas

BACKGROUND

We previously reported a high incidence of primary thyroid cancer in fluorodeoxyglucose positron-emission tomogram (FDG-PET)-detected incidental thyroid abnormalities. The aim of our study was to determine if these FDG-PET-detected thyroid malignancies represent a more-aggressive variant of primary thyroid carcinoma.

MATERIALS AND METHODS

All patients that underwent operative intervention for FDG-PET-detected incidental thyroid abnormalities were identified (June 2003 to April 2006). Patients with a diagnosis of primary thyroid carcinoma on final histopathology were included in the study. The patient demographics and histopathological findings were analyzed to identify adverse prognostic features.

RESULTS

In 11,500 patients, 17,250 FDG-PET scans were performed; 377 of these patients (3.2% of patients and 2.1% of FDG-PET scans) had findings positive for thyroid abnormality. Of the 32 patients that underwent operative intervention, 22 patients with a final diagnosis of primary thyroid malignancy were included in the study. A greater number of patients [12 patients, (54%)] were noted to harbor poor prognostic variants of primary thyroid carcinoma on final histopathology [tall-cell variant: 11 patients (50%) and poorly differentiated thyroid carcinoma: 1 patient (4%)]. Extra-thyroidal extension (ETE) was noted in the majority of patients [14 patients (63%)]. In patients with tall cell variant on final histopathology, the rate of ETE was even higher [10 patients (90%)].

CONCLUSION

Thyroid malignancies incidentally detected on FDG-PET scan harbor a high rate of unfavorable prognostic features and may represent a more-aggressive variant of primary thyroid carcinoma. These patients need to be subjected to further investigation with a view to possible operative intervention.

Molecular Profiling of Matched Samples Identifies Biomarkers of Papillary Thyroid Carcinoma Lymph Node Metastasis

Biomarkers of papillary thyroid carcinoma (PTC) metastasis can accurately identify metastatic cells and aggressive tumor behavior. To find new markers, serial analysis of gene expression (SAGE) was done on three samples from the same patient: normal thyroid tissue, primary PTC, and a PTC lymph node metastasis. This genomewide expression analysis identified 31 genes expressed in lymph node metastasis, but not in the primary tumor. Eleven genes were evaluated by quantitative real-time reverse transcription-PCR (qPCR) on independent sets of matched samples to find genes that were consistently different between the tumor and metastatic samples. LIMD2 and PTPRC (CD45) showed a statistically significant difference in expression between tumor and metastatic samples (P < 0.0045), and an additional gene (LTB) had borderline significance. PTPRC and LTB were tested by immunohistochemistry in an independent set of paired samples, with both markers showing a difference in protein expression. All 20 metastases from 6 patients showed expression in both markers, with little or no expression in primary tumor. Some of these markers could provide an improved means to detect metastatic PTC cells during initial staging of a newly diagnosed carcinoma and/or to rule out recurrence. The functional role of these genes may also provide insight into mechanisms of thyroid cancer metastasis.

MUC1 oncoprotein promotes refractoriness to chemotherapy in thyroid cancer cells

Overexpression of MUC1 oncoprotein is frequently observed in cancer and contributes to confer resistance to genotoxic agents. Papillary, follicular, and anaplastic thyroid carcinomas are the three forms of thyroid epithelial cancer. Anaplastic tumors are less differentiated and extremely aggressive, characterized by a poor prognosis. Little is known about the role of MUC1 in thyroid cancer. We recently showed that autocrine production of interleukin (IL)-4 and IL-10 controls thyroid cancer cell survival, growth, and resistance to chemotherapy through activation of Janus-activated kinase/signal transducers and activators of transcription (JAK/STAT) and phosphatidylinositide 3'-OH kinase (PI3K)/Akt pathways. In the present study, we showed that MUC1 COOH-terminal subunit (MUC1-C) is overexpressed in all the histologic variants of thyroid cancer cells and localizes to mitochondria where it interferes with the release of mitochondrial proapoptotic proteins. Moreover, IL-4 and IL-10 promote the increase of MUC1-C expression levels in normal thyroid cells, whereas blockage of both cytokines or neutralization of JAK/STAT and PI3K/Akt pathways through the exogenous expression of SOCS-1 and Akt(K179M) leads to a significant decrease of MUC1-C in primary thyroid cancer cells. Interestingly, down-regulation of MUC1 expression by direct targeting with RNA interference sensitizes anaplastic thyroid cancer cells to chemotherapy-induced apoptosis in vitro. Thus, MUC1 is a main component of the survival network acting in thyroid cancer and could be considered a key molecular target for sensitizing cancer cells to conventional or novel treatments.

Identifying a risk profile for thyroid cancer

The large use of simple and effective diagnostic tools has significantly contributed to the increase in diagnosis of thyroid cancer over the past years. However, there is compelling evidence that most micropapillary carcinomas have an indolent behavior and may never evolve into clinical cancers. Therefore, there is an urgent need for new tools able to predict which thyroid cancers will remain silent, and which thyroid cancers will present an aggressive behavior. There are a number of well-established clinical predictors of malignancy and recent studies have suggested that some of the patient’s laboratory data and image methods may be useful. Molecular markers have also been increasingly tested and some of them appear to be very promising, such as BRAF, a few GST genes and p53 polymorphisms. In addition, modern tools, such as immunocytochemical markers, and the measure of the fractal nature of chromatin organization may increase the specificity of the pathological diagnosis of malignancy and help ascertain the prognosis. Guidelines designed to select nodules for further evaluation, as well as new methods aimed at distinguishing carcinomas of higher aggressiveness among the usually indolent thyroid tumors are an utmost necessity.

Tall cell variant of papillary thyroid carcinoma without extrathyroid extension: biologic behavior and clinical implications

BACKGROUND

The tall cell variant (TCV) is a histologic subtype of papillary thyroid carcinoma (PTC) that is more aggressive than "classical" PTC. Most authors believe that TCV's worse prognosis is related to older age at presentation, larger tumor size, and high frequency of extrathyroid tumor extension (ETE). To assess the biologic and clinical behavior of TCV without ETE, we performed a detailed comparative clinicopathologic analysis of classical PTC and TCV without ETE.

METHODS

TCV was defined as a PTC harboring >50% tall cells, while classical PTC was restricted to those tumors containing >1% papillae and <30% tall cells. Microscopic analysis and chart review identified 62 cases of TCV and 83 classical PTC without ETE. These patients were analyzed for various pathologic, imaging, and clinical parameters including outcome.

RESULTS

There was no statistical difference between TCV and classical PTC in relation to age, gender, tumor size, risk stratification, type of therapy, and length of follow-up. TCV displayed more invasion of the tumor capsule and more often infiltrated into the thyroid capsule (p = 0.047 and 0.0004, respectively). Among patients with microscopically assessable regional lymph node (LN), 33 of 49 (67.3%) patients with TCV had LN metastasis at presentation, while only 24 of 60 (40%) classical PTC had positive nodes (p = 0.004). In multivariate analysis, histologic subtype (TCV vs. classical PTC) was the only independent factor associated with LN metastases (p = 0.007). In patients with adequate follow-up, 4 of 62 (6.5%) classical PTC and 7 of the 47 (14.9%) TCV had thyroid cancer recurrence (p = 0.202). TCV recurred at a distant site (3 of 47, 6.4%) while none of the 62 classical PTC developed distant metastases (p = 0.077).

CONCLUSION

TCV without ETE is biologically a more aggressive tumor than classical PTC without ETE independent of age, gender, and tumor size.

Perspectives and limitations of microarray-based gene expression profiling of thyroid tumors

Microarray technology has become a powerful tool to analyze the gene expression of tens of thousands of genes simultaneously. Microarray-based gene expression profiles are available for malignant thyroid tumors (i.e., follicular thyroid carcinoma, and papillary thyroid carcinoma), and for benign thyroid tumors (such as autonomously functioning thyroid nodules and cold thyroid nodules). In general, the two main foci of microarray investigations are improved understanding of the pathophysiology/molecular etiology of thyroid neoplasia and the detection of genetic markers that could improve the differential diagnosis of thyroid tumors. Their results revealed new features, not known from one-gene studies. Simultaneously, the increasing number of microarray analyses of different thyroid pathologies raises the demand to efficiently compare the data. However, the use of different microarray platforms complicates cross-analysis. In addition, there are other important differences between these studies: 1) some studies use intraindividual comparisons, whereas other studies perform interindividual comparisons; 2) the reference tissue is defined as strictly nonnodular healthy tissue or also contains benign lesions such as goiter, follicular adenoma, and hyperplastic nodules in some studies; and 3) the widely used Affymetrix GeneChip platform comprises several GeneChip generations that are only partially compatible. Moreover, the different studies are characterized by strong differences in data analysis methods, which vary from simple empiric filters to sophisticated statistic algorithms. Therefore, this review summarizes and compares the different published reports in the context of their study design. It also illustrates perspectives and solutions for data set integration and meta-analysis, as well as the possibilities to combine array analysis with other genetic approaches.

Prognostic Significance of the MUC1 and MUC4 Expressions in Thyroid Papillary Carcinoma

OBJECTIVES

The aim of the present study was to examine the expressions of mucin genes MUC1 and MUC4 and to evaluate the difference of their expressions in normal thyroid tissue, follicular adenoma, and papillary carcinoma. Furthermore, we aimed to estimate their prognostic significance in papillary carcinoma.

METHODS

We performed semiquantitative reverse-transcription polymerase chain reaction for determining the MUC1 and MUC4 mRNA expressions, and immunohistochemical staining was performed to determine the MUC1 and MUC4 protein expressions in 22 normal thyroid tissues, 22 follicular adenomas, and 15 papillary carcinomas. The semiquantitative scoring of the immunohistochemical staining was compared with the prognostic factors for thyroid carcinoma to evaluate the prognostic significance in 87 papillary carcinoma patients.

RESULTS

The MUC1 mRNA of the papillary carcinoma tissue showed an increased expression level compared with the other tissues. However, the expression level of MUC4 mRNA was weak in all the specimens, and this was not significantly different among the three groups. MUC1 immunoreactivity was more intense in papillary carcinoma but not in the other tissues. MUC4 was not expressed in all thyroid tissues. The expression of MUC1 was significantly associated with tumor size, extrathyroidal spread, and TNM stage (P < .05).

CONCLUSIONS

Up-regulation of MUC1 may play a more important role than that of MUC4 in the development of thyroid papillary carcinoma, and it may have some significance as a prognostic factor.

Downregulation of Fanconi anemia genes in sporadic head and neck squamous cell carcinoma

BACKGROUND/AIMS

Much of our understanding of human cancer has come from studies of the hereditary cancer predisposition syndromes. Fanconi anemia (FA) is an autosomal recessive disorder characterized by cellular hypersensitivity to DNA crosslinking agents, progressive bone marrow failure, and cancer predisposition to solid malignancies, especially head and neck squamous cell carcinoma (HNSCC). Since FA pathway-deficient cells are hypersensitive to DNA crosslinking chemotherapy agents, the presence of somatic FA gene inactivation in sporadic cancers may be of clinical interest. This study sought to determine the frequency of FA gene downregulation in sporadic HNSCC.

METHODS

The expression of the FA genes FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCJ, FANCL and FANCM in 11 HNSCC cell lines and 49 tongue carcinoma samples was studied with quantitative real-time polymerase chain reaction.

RESULTS

Downregulation of at least one FA gene was observed in 3 of 11 HNSCC cell lines and 66% of tongue carcinoma samples. FANCB, FANCF, FANCJ and FANCM were most commonly affected by downregulation, whereas downregulation of FANCA, FANCE and FANCD2 was rare.

CONCLUSION

Our data suggest that downregulation of FA genes is common in sporadic HNSCC. The clinical implications of this finding merit further study. .

[MUC1 (EMA): A key molecule of carcinogenesis?]

MUC1 is a large trans-membrane highly glycosylated mucin which is expressed at the apical pole of normal cells in glandular epithelia. MUC1 is implicated in many physiological mechanisms such as adhesion, development and differentiation. Also, MUC1 is frequently deregulated and over-expressed with a membrane circumferential and/or cytoplasmic expression. The intracellular tail of MUC1 is phosphorylated and can interact with many signalling proteins and transcriptional factors. Indeed, MUC1 can interact with B-catenin competitively for E-cadherin, thus destabilizing intercellular junctions and favouring metastatic dissemination. In carcinomas, the overexpression and membrane delocalization of MUC1 is associated with a worse prognosis and a shorter survival in breast, colon, kidney, prostate or gastro-intestinal cancers. MUC1 appears to be a novel therapeutic target for immunotherapy or anti-tumour vaccines.

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.

The cytoplasmic expression of MUC1 in papillary thyroid carcinoma of different histological variants and its correlation with cyclin D1 overexpression

This study addressed the immunohistochemical expression of MUC1 in papillary thyroid carcinoma (PTC) of different histotypes, sizes, and morphological features of aggressiveness, and its correlation with the overexpression of cyclin D1, a target molecule of the Wnt pathway. MUC1 expression was examined in a total of 209 PTCs. Cytoplasmic MUC1 expression was elevated in the tall, columnar cell and oncocytic variants (100%), Warthin-like (78%), and conventional PTCs (61%), and in papillary microcarcinoma (PMC) with the conventional growth pattern (52%). On the contrary, it was low in the follicular variant (27%) of PTC and PMCs with follicular architecture (13%). Cytoplasmic MUC1 accumulation did not associate with any clinicopathological features except peritumoral lymphoid infiltration in PTCs and in PMCs with the conventional growth pattern. MUC1 staining correlated with cyclin D1 overexpression in conventional PTCs and PMCs and PMCs with follicular architecture. The results demonstrate that MUC1 expression varies broadly in different histological variants of PTC, being the lowest in tumors with follicular structure. In general, it does not prove to be a prognosticator of PTC aggressiveness. A high correlation between MUC1 and cyclin D1 implies MUC1 involvement in the Wnt cascade functioning in a large subset of human PTCs and PMCs.

High survivin expression is associated with favorable outcome in advanced primary oral squamous cell carcinoma after radiation therapy

Oral squamous cell carcinoma (OSCC) is a solid neoplasm exhibiting aggressive tumor phenotypes with unpredictable biological behavior. Recent studies suggested that high expression of the antiapoptotic protein survivin might be associated with adverse outcome in oral cancer patients. To investigate, whether increased copy numbers of the survivin-encoding gene BIRC5 results in elevated survivin levels and whether BIRC5 and survivin could serve as progression markers in the clinical course of OSCC, tumor tissue microarray analysis was performed applying fluorescence in situ hybridization and immunohistochemistry to 296 OSCC specimens. Gene copy number gain of BIRC5 was detected in 33.9% (150/227) of cases, which correlated significantly with high UICC stage and the presence of lymph node metastases (p = 0.003 and p = 0.001, respectively), but not with unfavorable patients' outcome (p > 0.05) in multivariate analysis. High survivin expression was found in 67.3% (169/251) of cases to predict increased 5- and 10-year overall survival of patients in a multivariate model including UICC stage and age as covariables (p = 0.035 and p = 0.026, respectively). Within a subgroup of patients, who received radiation therapy (n = 121), high survivin expression was found to be the only predictor of favorable 3-, 5- and 10-year overall survival in a multivariate cox regression analysis including UICC stage and age as covariables (p = 0.001, p = 0.004 and p = 0.006, respectively). In conclusion, high survivin expression might be useful to identify OSCC patients, who would benefit from radiotherapy.

Genetic considerations in thyroid cancer

BACKGROUND

Recent molecular studies have described a number of abnormalities associated with the progression and dedifferentiation of thyroid carcinoma. These distinct molecular events are often associated with specific stages of tumor development. A better understanding of the mechanisms involved in thyroid cancer pathogenesis may help to translate these discoveries toward improvements in patient care.

METHODS

We reviewed the literature on the molecular pathogenesis of thyroid cancer and compared clinical, histopathologic, and genetic features important in defining the disease process.

RESULTS

The progression of thyroid cancer from well-differentiated to poorly differentiated and undifferentiated carcinoma represents a biological continuum. Specific genetic events serve as early initiating and late triggering events. Poorly differentiated thyroid carcinomas occupy an intermediate position in this progression model.

CONCLUSIONS

With sophisticated genetic tools generating a wealth of information, we have gained better insight into the mechanisms driving thyroid tumor progression. Recognition of these features is crucial to the management of patients with thyroid cancer. Novel treatments are being designed based on our enhanced understanding of this disease process.

Novel molecular markers in well-differentiated thyroid cancers

Conventional cytopathology is an excellent tool for distinguishing benign from malignant thyroid nodules with high sensitivity and specificity. However, significant numbers of cases are indeterminate, resulting in many ultimately unnecessary diagnostic thyroidectomies. Numerous molecular markers have been studied in an attempt to improve the diagnostic accuracy of thyroid fine-needle aspiration cytology. Several markers, such as galectin-3 and thyroid peroxidase, have been extensively assessed and shown not only to differentiate malignant tumors from benign thyroid lesions with high sensitivity and specificity, but also to identify tumors associated with poor outcome. More recently, four other genes (PTTG, PBF, BRAF and MUC1) have been identified that show real promise as potential molecular markers in thyroid cancer, offering discrimination between tumor subtypes and providing valuable prognostic information. However, larger, well-controlled studies are needed before their introduction into routine clinical practice. The search for molecular markers represents one of the most exciting areas in translational thyroid cancer research. We are optimistic that molecular markers will be used in the near future as adjuncts to conventional histological techniques to improve diagnostic accuracy of fine-needle aspiration cytology for thyroid lesions, particularly those that are cytologically indeterminate.

Genomic screening of head and neck cancer and its implications for therapy planning

Despite great technical improvements in radiotherapy and surgery, survival for patients with squamous cell carcinoma of the head and neck (SCCHN) has still not improved significantly over the last decades. Management of SCCHN has mainly been based on the TNM staging and site over this time period, even though we know that there are individual differences independent of the TNM status. Individual patients with small tumors might have a poor outcome, and patients with large tumors may end up with a favorable prognosis, despite their respective TNM classification. Recent molecular studies indicate that underlying genetic abnormalities may reflect such individual differences independently of TNM status. Individualization of treatment based on such biological properties of the tumors might result in less over as well as under treatment. However, the optimal panel of biomarkers to be used for the individualization of treatment is yet to be defined. A variety of laboratory techniques have been used in studies that investigate the individual biological features, spanning from methods that screen the genome for chromosomal and genetic abnormalities, e.g., cytogenetics, CGH, SKY and cDNA micro array, to detailed studies of specific aberrations. The purpose of this review of the literature is to summarize what has been studied so far by methods for genetic screening and to relate these results to the prediction of the clinical outcome. We conclude that it is time to focus future prospective studies on how treatment can be individualized based on biomarkers in combination with the macroscopic features of SCCHN.

Differential cell cycle-regulatory protein expression in biliary tract adenocarcinoma: correlation with anatomic site, pathologic variables, and clinical outcome

PURPOSE

Biliary tract adenocarcinomas (BTAs), although anatomically related, arise through ill-defined and possibly different location-related pathogenetic pathways. This clinicopathologic study characterizes differences in cell cycle-regulatory protein expression across the spectrum of BTA.

METHODS

Tissue microarrays were prepared from paraffin-embedded surgical specimens with triplicate cores of BTA and benign tissue. Immunohistochemical expression of p53, cyclin D1, p21, Bcl2, p27, Mdm2, and Ki-67 was assessed, and the results were correlated with pathologic variables and survival. Hierarchical clustering was used to partition the data based on protein expression, and then the data were analyzed according to anatomic location.

RESULTS

Tissue from 128 surgical patients (1992 to 2002) was obtained. Tumor sites of origin were intrahepatic cholangiocarcinoma (IH; n = 23), hilar cholangiocarcinoma (Hilar; n = 54), gallbladder (GB; n = 32), and distal bile duct (Distal; n = 19). p27 expression decreased progressively from proximal to distal in the biliary tree and correlated with location-related differences in outcome; cyclin D1 and Bcl2 overexpression also varied according to anatomic site. Aberrant p53 staining and cyclin D1 overexpression were lower in papillary tumors compared with the more common sclerosing tumors. The expression profiles of GB and Hilar were more similar to each other than either was to IH or Distal (86% clustering in the first partition). After an R0 resection, overexpression of Mdm2 (P = .0062) and absent p27 expression (P = .0165) independently predicted poor outcome.

CONCLUSION

BTAs differentially express cell cycle-regulatory proteins based on tumor location and morphology. Prognostic roles were identified for Mdm2 and p27. Overlap in the pathogenesis of GB and Hilar tumors was suggested.

Identification of Differentially Expressed Genes in Papillary Thyroid Carcinomas With and Without Rearrangements of the Tyrosine Kinase Receptors RET and/or NTRK1

BACKGROUND

The transforming capacities of RET and/or NTRK1 chimeric oncogenes as well as the molecular background of non-rearranged papillary thyroid carcinomas (PTCs) remain to be elucidated. To assess altered gene expression, we examined PTCs with and without tyrosine kinase receptor rearrangements by mRNA differential display (DD).

MATERIALS AND METHODS

Six of 13 PTCs examined harbored RET chimeras (3x RET/PTC1, 1x RET/PTC3) and/or NTRK1 chimeras (2x trk, 1x TRK-T3, 2 unknown TRK hybrids). The method of DD analysis was refined by a novel fragment-recovery technique using a high-performance fluorescence scanner.

RESULTS

Of 500 up- or down-regulated mRNA transcripts, 19 selected fragments were recovered, cloned, sequenced, and identified. The accuracy and high degree of reproducibility of the method was demonstrated. Differential expression of gene products with potential association to cell proliferation or tumor progression was observed, such as 14-3-3beta and Rab27a. Moreover, several gene products with unknown functions were demonstrated in PTCs bearing RET or NTRK1 hybrids versus rearrangement-negative PTCs, including a homologue of the Ig kappa light chain constant region.

CONCLUSIONS

Candidate transcripts with presumed tumorigenic potential in other solid tumors may prove to be relevant in the progression of PTCs, too. Most promising is the isolation of several differentially expressed, yet unknown, genes that may open new insights in the pathogenesis or progression of PTC.

MUC1 plays a role in tumor maintenance in aggressive thyroid carcinomas

BACKGROUND

We recently identified MUC1 as a target driving selection for 1q21 amplification and validated it as an independent marker of aggressive behavior in thyroid cancer (TC). The aims of this study were to determine whether TC cell lines retain MUC1 expression patterns that are seen in primary tumors, assess the role of MUC1 in tumor maintenance, and develop a virally delivered anti-MUC1 RNA interference (RNAi) that is effective in decreasing MUC1 expression in vitro.

METHODS

Fifteen TC cell lines were screened for MUC1 protein expression. Cell lines with varying MUC1 protein levels were treated with anti-MUC1 monoclonal antibody to assess cell viability. A recombinant retroviral short hairpin RNAi delivery system against MUC1 was developed. Efficacy and optimal dosing of short hairpin RNA against MUC1 was determined.

RESULTS

MUC1 expression patterns in TC cell lines were found to be similar to that seen in primary tumors. Treatment with anti-MUC1 antibody resulted in a significant decrease in cell viability in MUC1 over-expressing cell lines. MUC1-779 RNAi construct showed excellent infection efficiency and reproducible silencing.

CONCLUSION

These data offer functional evidence that implicates MUC1 over-expression as a key molecular event in the pathogenesis of aggressive TC. Retrovirally delivered anti-MUC1 RNAi is effective in silencing MUC1 and merits further investigation to establish therapeutic efficacy and safety in anticipation of potential clinical application.

Gene expression in poorly differentiated papillary thyroid carcinomas

We used cDNA microarrays to study gene expression in fresh frozen papillary thyroid carcinoma (PTC) specimens. Seven clinically aggressive carcinomas were included, comprising poorly differentiated PTC and tumors with extensive local invasion or synchronous distant metastases. Ten differentiated (classic) papillary thyroid carcinomas (PTC) and non-neoplastic thyroid tissues were also investigated. TaqMan quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry verified the differential gene expression. The B-Raf gene was mutated with a T-->A transversion at nucleotide 1799 (V600E) in 8 of 10 differentiated PTC, and in 4 of 7 aggressive carcinomas. Among genes markedly and equally over-expressed in carcinomas of both the aggressive and classic PtC groups, compared to normal thyroid tissue, were CBP/p300 transactivator (CItED1), fibronectin, growth/differentiation factor 15, potassium inwardly rectifying channel KCNJ2, glutaminyl peptide cyclotransferase, WNT7A, and dipeptidyl peptidase IV. A marked upregulation in carcinomas of P-cadherin mRNA and protein concomitant with E-cadherin downregulation, indicates a possible P-E cadherin "switch" in PTC. The growth factor homologue Nel-like 2, dual specificity phosphatase 5, the serine protease kallikrein 10, and also the tight junction genes claudin 1 and claudin 16, were upregulated in classic PTC but not in aggressive tumors, which may be consistent with altered cell polarity in the dedifferentiated PtC. The aggressive, poorly differentiated PtC group was specifically characterized by marked upregulation of several genes related to cell proliferation such as cell division cycle 2 (CDC2), CDC7, kinesin-like 5, ubiquitin conjugating enzyme E2C, and topoisomerase IIalpha, and by upregulation of genes encoding extracellular matrix proteins such as seprase, extracellular matrix protein 1, and several collagens. These aggressive tumors were also characterized by overexpression of the integrin ligand periostin, and in some biopsies also of osteopontin and of the upstream Rac-regulator dedicator of cytokinesis 10 (DOCK10). These data are interpreted to be consistent with altered cell motility, extracellular matrix remodeling and increased cell proliferation, as important processes in PTC tumor progression.

Chromosomal aberrations in squamous cell carcinomas of the upper aerodigestive tract: biologic insights and clinical opportunities

Oncogenesis results from a progressive accumulation of genetic aberrations consequent to a complex interplay between carcinogenic factors and innate infidelity of DNA surveillance mechanisms. Although the development of genetic aberrations is random, those conferring survival advantages are selected for in a Darwinian manner, thus allowing continuous adaptation to selection pressures. Chromosomal aberrations are a prominent manifestation of genetic damage, which can be closely linked with tumor behavior and outcome as exemplified by curative treatment of chronic myelogenous leukemia resulting from targeting the BCR-ABL translocation. In the case of head and neck squamous cell carcinomas (HNSCC), chromosomal changes are detectable at all stages of tumor development, providing excellent opportunities for genomic prognostication and therapy. Several studies have shown that the overall genomic profile of HNSCC is highly consistent, but individual tumors vary significantly in their complement of genetic alterations, thereby confounding clinical correlation. The application of modern genetic and bioinformatic analytic approaches has facilitated the identification of critical genomic changes in HNSCC, many of which have been linked to clinical outcome. These genetic aberrations represent excellent targets for novel therapeutics, but require validation. The initiation of phase III trials evaluating the therapeutic utility of genetic aberrations suggests a promising future for genome-based treatment of HNSCC.

Genetic Classification of Lung Adenocarcinoma Based on Array-Based Comparative Genomic Hybridization Analysis: Its Association with Clinicopathologic Features

The array-based comparative genomic hybridization using microarrayed bacterial artificial chromosome clones allows high-resolution analysis of genome-wide copy number changes in tumors. To analyze the genetic alterations of primary lung adenocarcinoma in a high-throughput way, we used laser-capture microdissection of cancer cells and array comparative genomic hybridization focusing on 800 chromosomal loci containing cancer-related genes. We identified a large number of chromosomal numerical alterations, including frequent amplifications on 7p12, 11q13, 12q14-15, and 17q21, and two homozygous deletions on 9p21 and one on 8p23. Unsupervised hierarchical clustering analysis of multiple alterations revealed three subgroups of lung adenocarcinoma that were characterized by the accumulation of distinct genetic alterations and associated with smoking history and gender. The mutation status of the epidermal growth factor receptor (EGFR) gene was significantly associated with specific genetic alterations and supervised clustering analysis based on EGFR gene mutations elucidated a subgroup including all EGFR gene mutated tumors, which showed significantly shorter disease-free survival. Our results suggest that there exist multiple molecular carcinogenesis pathways in lung adenocarcinoma that may associate with smoking habits and gender, and that genetic cancer profiling will reveal previously uncharacterized genetic heterogeneity of cancer and be beneficial in estimating patient prognosis and discovering novel cancer-related genes including therapeutic targets.

The MUC1 SEA Module Is a Self-cleaving Domain

MUC1, a glycoprotein overexpressed by a variety of human adenocarcinomas, is a type I transmembrane protein (MUC1/TM) that soon after its synthesis undergoes proteolytic cleavage in its extracellular domain. This cleavage generates two subunits, alpha and beta, that specifically recognize each other and bind together in a strong noncovalent interaction. Proteolysis occurs within the SEA module, a 120-amino acid domain that is highly conserved in a number of heavily glycosylated mucin-like proteins. Post-translational cleavage of the SEA module occurs at a site similar to that in MUC1 in the glycoproteins IgHepta and MUC3. However, as in the case of other proteins containing the cleaved SEA module, the mechanism of MUC1 proteolysis has not been elucidated. Alternative splicing generates two transmembrane MUC1 isoforms, designated MUC1/Y and MUC1/X. We demonstrated here that MUC1/X, whose extracellular domain is comprised solely of the SEA module in addition to 30 MUC1 N-terminal amino acids, undergoes proteolytic cleavage at the same site as the MUC1/TM protein. In contrast, the MUC1/Y isoform, composed of an N-terminally truncated SEA module, is not cleaved. Cysteine or threonine mutations of the MUC1/X serine residue (Ser-63) immediately C-terminal to the cleavage site generated cleaved proteins, whereas mutation of the Ser-63 residue of MUC1/X to any other of 17 amino acids did not result in cleavage. In vitro incubation of highly purified precursor MUC1/X protein resulted in self-cleavage. Furthermore, addition of hydroxylamine, a strong nucleophile, markedly enhanced cleavage. Both these features are signature characteristics of self-cleaving proteins, and we concluded that MUC1 undergoes autoproteolysis mediated by an N --> O-acyl rearrangement at the cleavage site followed by hydrolytic resolution of the unstable ester and concomitant cleavage. It is likely that all cleaved SEA module-containing proteins follow a similar route.

ECM1 and TMPRSS4 Are Diagnostic Markers of Malignant Thyroid Neoplasms and Improve the Accuracy of Fine Needle Aspiration Biopsy

OBJECTIVE

The objective of this study was to determine whether genes that regulate cellular invasion and metastasis are differentially expressed and could serve as diagnostic markers of malignant thyroid nodules.

SUMMARY AND BACKGROUND DATA

Patients whose thyroid nodules have indeterminate or suspicious cytologic features on fine needle aspiration (FNA) biopsy require thyroidectomy because of a 20% to 30% risk of thyroid cancer. Cell invasion and metastasis is a hallmark of malignant phenotype; therefore, genes that regulate these processes might be differentially expressed and could serve as diagnostic markers of malignancy.

METHODS

Differentially expressed genes (2-fold higher or lower) in malignant versus benign thyroid neoplasms were identified by extracellular matrix and adhesion molecule cDNA array analysis and confirmed by real-time quantitative polymerase chain reaction (PCR). The area under the receiver operating characteristic (AUC) curve was calculated to determine diagnostic accuracy of gene expression level cutoffs established by logistic regression analysis.

RESULTS

By cDNA array analysis, ADAMTS8, ECM1, MMP8, PLAU, SELP, and TMPRSS4 were upregulated, and by quantitative PCR, ECM1, SELP, and TMPRSS4 mRNA expression was higher in malignant (n = 57) than in benign (n = 38) thyroid neoplasms (P< 0.002). ECM1 and TMPRSS4 mRNA expression levels were independent predictors of a malignant thyroid neoplasm (P < 0.003). The AUC was 0.956 for ECM1 and 0.926 for TMPRSS4. Combining both markers improved their diagnostic use (AUC 0.985; sensitivity, 91.7%; specificity, 89.8%; positive predictive value, 85.7%; negative predictive value, 82.8%). ECM1 and TMPRSS4 expression analysis improved the diagnostic accuracy of FNA biopsy in 35 of 38 indeterminate or suspicious results. The level of ECM1 mRNA expression was higher in TNM stage I differentiated thyroid cancers than in stage II and III tumors (P < or = 0.031).

CONCLUSIONS

ECM1 and TMPRSS4 are excellent diagnostic markers of malignant thyroid nodules and may be used to improve the diagnostic accuracy of FNA biopsy. ECM1 is also a marker of the extent of disease in differentiated thyroid cancers.

Gene-expression profiling in differentiated thyroid cancer – a viable strategy for the practice of genomic medicine?

Thyroid neoplasias have been largely ignored as an active field of investigation due to the overall favorable prognosis of differentiated nonmedullary thyroid cancers. However, differentiated thyroid cancers have the highest estimated annual percentage increase in incidence amongst all cancer sites. Furthermore, no significant progress has been made to improve survival, especially for advanced disease. Compounding the problem, there remains a lack of highly accurate preoperative markers or molecular-based predictive models to differentiate benign from malignant follicular neoplasias, thus we continue to rely upon surgery for diagnostic purposes in this subset of patients. Therefore, new approaches are necessary to identify potential novel diagnostic, prognostic and therapeutic algorithms, which would not only allow accurate early diagnosis but also personalized patient management, with clinical management and surveillance tailored according to the genetic signature of the patient. The advent of modern genomic technologies, such as global gene-expression profiling, may begin to provide the data required for the evidence-based practice of genomic medicine as it relates to thyroid neoplasia. However, it is already clear that genomic technology alone is insufficient to fully achieve this vision.