Molecular genetic analysis of primary renal epithelial tumours with granular oncocytic cytoplasms / Análisis genético molecular de tumores epiteliales renales primarios con citoplasma oncocítico granular

SUMMARY: The group of primary renal tumours with granular-oncocytic cytoplasm is a very heterogeneous group, in its histological origin and biological behavior resulting in many diagnostic problems. In this study 57 renal epithelial tumours with granular oncocytic cells were analyzed using fluorescence in situ hybridisation (FISH), array comparative genomic hybridisation (aCGH) and polymerase chain reaction (PCR). The results of analysis in renal oncocytoma (RO) did not indicate the presence of the gene mutations or chromosomal abnormalities. Sporadic renal hybrid oncocytic/chromophobe tumours (HOCT) had multiple numerical aberrations of chromosomes 1, 2, 6, 9, 10, 13, 17, 20, 21 and 22. This type of tumour had no mutations in the VHL, c-kit, PDGFRA, and FLCN genes. Oncocytic papillary renal cell carcinoma (O-PRCC) had numerical abnormalities of chromosomes 7 and 17 and the loss of the Y chromosome. Cytogenetic analysis of 20 pigmented microcystic chromophobe renal cell carcinomas (PMChRCC) showed monosomy as the most frequent aberration in all analyzed chromosomes 1, 2, 5, 10, 13, 17 and 21. One case of chromophobe renal cell carcinoma (ChRCC) with hyaline globules had a mutation in the distal part of exon 3 of the VHL gene. Absence of genetic disorders in usual RO is common result, but we have established absence of genetic disorders even in rare variants. Variety of genetic alterations detected in sporadic renal HOCT proves it to be a separate entity, not a variant of ChRCC, while PMChRCC is an uncommon variant of ChRCC. O-PRCC is a subtype of papillary renal cell carcinoma.

RESUMEN: El grupo de tumores renales primarios con citoplasma granular-oncocítico es un grupo muy heterogéneo, en su origen histológico y comportamiento biológico, resultando en problemas de diagnóstico. En el estudio se analizaron 57 tumores epiteliales renales con citoplasma oncocítico granular mediante hibridación fluorescente in situ (FISH), hibridación genómica comparativa de matriz (aCGH) y reacción en cadena de la polimerasa (PCR). Los resultados del análisis en oncocitoma renal (RO) no indicaron la presencia de mutaciones genéticas ni anomalías cromosómicas. Los tumores oncocíticos / cromófobos híbridos renales esporádicos (HOCT) tenían múltiples aberraciones numéricas de los cromosomas 1, 2, 6, 9, 10, 13, 17, 20, 21 y 22. No se observaron mutaciones en este tipo de tumor en el VHL, c-kit, PDGFRA y genes FLCN. El carcinoma de células renales papilar oncocítico (O-PRCC) tenía anomalías numéricas de los cromosomas 7 y 17 y la pérdida del cromosoma Y. El análisis citogenético de 20 carcinomas de células renales cromófobos microquísticos pigmentados (PMChRCC) mostró que la monosomía era la aberración más frecuente en todos los cromosomas analizados 1, 2, 5, 10, 13, 17 y 21. Un caso de carcinoma de células renales cromófobo (CCRc) hialino tenía una mutación en la parte distal del exón 3 del gen VHL. La ausencia de trastornos genéticos en la OI habitual es un resultado común, pero hemos establecido la ausencia de trastornos genéticos incluso en variantes raras. Varias alteraciones genéticas detectadas en esporádica HOCT renal demuestran que es una entidad separada, no una variante de ChRCC, mientras que PMChRCC es una variante poco común de ChRCC. O-PRCC es un subtipo de carcinoma papilar de células renales.

Molecular profile of Hürthle cell carcinomas: recurrent mutations in the Wnt/ß-catenin pathway.

OBJECTIVE: Genomic alterations in Hürthle cell carcinomas (HCC) include chromosomal losses, mitochondrial DNA mutations, and changes in the expression profile of the PI3K-AKT-mTOR and Wnt/ß-catenin pathways. This study aimed at characterizing the mutational profile of HCC. METHODS: Next-generation sequencing (NGS) of 40 HCC using a 102-gene panel including, among others, the MAPK, PI3K-AKT-mTOR, Wnt/ß-catenin, and Notch pathways. HCC was widely invasive in 57.5%, and lymph node and distant metastases were diagnosed in 5% and 7.5% of cases. During follow-up, 10% of patients presented with persistent/recurrent disease, but there were no cancer-related deaths. RESULTS: Genetic alterations were identified in 47.5% of HCC and comprised 190 single-nucleotide variants and 5 insertions/deletions. The Wnt/ß-catenin pathway was most frequently affected (30%), followed by MAPK (27.5%) and PI3K-AKT-mTOR (25%). FAT1 and APC were the most frequently mutated genes and present in 17.5%. RAS mutations were present in 12.5% but no BRAF mutation was found. There was no association between the mutational profile and clinicopathological features. CONCLUSIONS: This series of HCC presents a wide range of mutations in the Wnt/ß-catenin, MAPK and PI3K-AKT-mTOR pathways. The recurrent involvement of Wnt/ß-catenin pathway, particularly mutations in APC and FAT1, are of particular interest. The data suggest that mutated FAT1 may represent a potential novel driver in HCC tumorigenesis and that the Wnt/ß-catenin pathway plays a critical role in this distinct thyroid malignancy.

PVALB, a new Hürthle adenoma diagnostic marker identified through gene expression.

CONTEXT: A better means to accurately identify malignant thyroid nodules and to distinguish them from benign tumors is needed. We previously identified markers for detecting thyroid malignancy, with sensitivity estimated at or close to 100%. One lingering problem with these markers was that false positives occurred with Hürthle cell adenomas (HCA) which lowered test specificity. METHODS: To locate accurate diagnostic markers, we profiled in depth the transcripts of a HCA and a Hürthle cell carcinoma (HCC). From 1146 differentially expressed genes, 18 transcripts specifically expressed in HCA were tested by quantitative PCR in a wide range of thyroid tumors (n = 76). Sensibility and specificity were calculated using receiver operating characteristic (ROC). Selected markers were further validated in an independent set of thyroid tumors (n = 82) by immunohistochemistry. To define the panel that would yield best diagnostic accuracy, these markers were tested in combination with our previous identified markers. RESULTS: Seventeen of the 18 genes showed statistical significance based on a mean relative level of expression (P < 0.05). KLK1 (sensitivity = 0.97) and PVALB (sensitivity = 0.94) were the best candidate markers. The combination of PVALB and C1orf24 increased specificity to >97% and maintained sensitivity for detection of carcinoma. CONCLUSION: We identified tumor markers that can be used in combination for a more accurate preoperative diagnosis of thyroid nodules and for postoperative diagnosis of thyroid carcinoma in tumor sections. This improved test would help physicians rapidly focus treatment on true malignancies and avoid unnecessary treatment of benign tumors, simultaneously improving medical care and reducing costs.

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.

Origin of renal cell carcinomas.

Cancer is a heritable disorder of somatic cells: environment and heredity are both important in the carcinogenic process. The primal force is the "two hits" of Knudson's hypothesis, which has proved true for many tumours, including renal cell carcinoma. Knudson et al. [1, 2] recognised that familial forms of cancer might hold the key to the identification of important regulatory elements known as tumour-suppressor genes. Their observations (i.e., that retinoblastoma tend to be multifocal in familial cases and unifocal in sporadic presentation) led them to propose a two-hit theory of carcinogenesis. Furthermore, Knudson postulated that patients with the familial form of the cancer would be born with one mutant allele and that all cells in that organ or tissue would be at risk, accounting for early onset and the multifocal nature of the disease. In contrast, sporadic tumours would develop only if a mutation occurred in both alleles within the same cell, and, as each event would be expected to occur with low frequency, most tumours would develop late in life and in a unifocal manner [3, 4]. The kidney is affected in a variety of inherited cancer syndromes. For most of them, both the oncogene/tumour-suppressor gene involved and the respective germline mutations have been identified. Each of the inherited syndromes predisposes to distinct types of renal carcinoma. Families with hereditary predisposition to cancer continue to provide a unique opportunity for the identification and characterisation of genes involved in carcinogenesis. A surprising number of genetic syndromes predispose to the development of renal cell carcinoma, and genes associated with five of these syndromes have been already identified: VHL, MET, FH, BHD and HRPT2. Few cancers have as many different types of genetic predisposition as renal cancer, although to date only a small proportion of renal cell cancers can be explained by genetic predisposition.

20 years of RET/PTC in thyroid cancer: clinico-pathological correlations.

The RET/PTC oncogene has been isolated almost twenty years ago. During these years, the research has given a final answer to several questions. In fact, it has been demonstrated that: a) RET/PTC is an early event in the process of thyroid carcinogenesis and has a critical role in the generation of the papillary carcinoma; b) RET/PTC activation is essentially restricted to the papillary histotype and to the Hürthle thyroid tumors; c) its incidence increases after exposure to radiations. However, some questions have not found a final answer yet: a) which is the real frequency of RET/PTC activation? Likely it is around 20%, but this point is still questionable; b) which other gene modifications are required to lead a thyroid cell carrying a RET/PTC oncogene to the malignant phenotype?, and c) is there any correlation between RET/PTC activation and clinical parameters? We hope that these questions will have a clear answer in the near future.

[Nodule diagnosed as follicular patterned lesion: are biomarkers the promise?]. / Nódulos com diagnóstico de padrão folicular: marcadores biológicos são o futuro?

There are an increasing number of thyroid nodules found by ultrasound and sampled by fine needle aspiration (FNA). A clinical problem is the accurate distinction between benign and malignant forms of follicular lesion. In this review we discuss the thyroid lesions that are common sources of diagnostic error, and grouped together as follicular patterned lesion, and the molecular markers identified by us and others, and that are able to distinguish the benign from the malignant ones.

20 years of RET/PTC in thyroid cancer: clinico-pathological correlations

The RET/PTC oncogene has been isolated almost twenty years ago. During these years, the research has given a final answer to several questions. In fact, it has been demonstrated that: a) RET/PTC is an early event in the process of thyroid carcinogenesis and has a critical role in the generation of the papillary carcinoma; b) RET/PTC activation is essentially restricted to the papillary histotype and to the Hürthle thyroid tumors; c) its incidence increases after exposure to radiations. However, some questions have not found a final answer yet: a) which is the real frequency of RET/PTC activation? Likely it is around 20 percent, but this point is still questionable; b) which other gene modifications are required to lead a thyroid cell carrying a RET/PTC oncogene to the malignant phenotype?, and c) is there any correlation between RET/PTC activation and clinical parameters? We hope that these questions will have a clear answer in the near future.

O oncogene RET/PTC foi isolado há quase 20 anos atrás. Durante esses anos de pesquisa várias questões foram solucionadas. Na verdade, já foi demonstrado que: a) o RET/PTC é um evento precoce no processo da carcinogênese da tiróide e tem um papel crítico na geração do carcinoma papilífero; b) a ativação do RET/PTC está restrita essencialmente ao histotipo papilar e aos tumores de Hürthle; c) sua incidência aumenta após a exposição à radiação. Entretanto, algumas questões permanecem ainda sem uma resposta final: a) qual é a real freqüência de ativação do RET/PTC? Provavelmente em torno de 20 por cento, mas este número ainda é questionável; b) quais outras modificações gênicas são necessárias para transformar uma célula tiroidiana que possui oncogene RET/PTC no fenotipo maligno?; e c) existe alguma correlação entre a ativação do RET/PTC e parametros clínicos? Esperamos que essas questões sejam solucionadas em futuro próximo.

Nódulos com diagnóstico de padrão folicular: marcadores biológicos são o futuro? / Nodule diagnosed as follicular patterned lesion: are biomarkers the promise?

Com o uso da ultra-sonografia de alta resolução, a prevalência de nódulos tem aumentado e, conseqüentemente, o número de punção aspirativa por agulha fina (PAAF), que é o método de escolha para diagnóstico inicial. Um dos maiores dilemas clínicos para o citologista é o diagnóstico diferencial das lesões foliculares comumente agrupadas na classe padrão folicular. Neste artigo de revisão, discutiremos quais são as lesões que podem ser assim classificadas e os marcadores moleculares, identificados por nós ou por outros grupos, que são capazes de distinguir as lesões benignas das malignas.

There are an increasing number of thyroid nodules found by ultrasound and sampled by fine needle aspiration (FNA). A clinical problem is the accurate distinction between benign and malignant forms of follicular lesion. In this review we discuss the thyroid lesions that are common sources of diagnostic error, and grouped together as follicular patterned lesion, and the molecular markers identified by us and others, and that are able to distinguish the benign from the malignant ones.

Is agNOR and DNA ploidy analysis useful for evaluating thyroid neoplasms?

OBJECTIVE: To correlate the subjective AgNOR counting method and DNA content with histologic diagnoses of thyroid cancer and invasion. STUDY DESIGN: Eighty-one consecutive cases of thyroid carcinoma were selected for DNA and AgNOR analysis. The diagnoses were: papillary carcinoma (n = 40), follicular carcinoma (n = 31), Hürthle cell adenocarcinoma (n = 4), and undifferentiated carcinoma (n = 6). Seven normal thyroids were used as controls. DNA quantitative measurement was performed with Vidas 2.0 software (Kontron Bildanalyse, Munich, Germany) connected to an MPM 210 photometer microscope (Carl Zeiss, Oberkochen, Germany). The DNA index was obtained using histograms. Counting the NORs was performed by subjectively counting the NORs in 200 malignant cells. RESULTS: DNA ploidy analysis showed all Hürthle cell adenocarcinomas, 21 (67%)follicular tumors, 23 (57%) papillary tumors and 4 (67%) undifferentiated carcinomas to be aneuploid. DNA analysis correlated with histologic type of the tumor (p = 0.032). There was no statistical significance to the AgNOR counting variables studied. Statistical analysis showed correlation between ploidy and histologic diagnosis, but not AgNOR counting, to have prognostic value. CONCLUSION: DNA ploidy is more useful than subjective counting of NORs as an adjunct method for thyroid lesion analysis.