Profiling and classification tree applied to renal epithelial tumours

Three-dimensional coculture provides an improved in vitro model for papillary renal cell carcinoma

Papillary renal cell carcinoma (pRCC) represents the second most common kidney cancer and can be distinguished from other types based on its unique histological architecture and specific pattern of genomic alterations. Sporadic type 1 pRCC is almost universally driven by focal or chromosomal amplification of the receptor tyrosine kinase MET, although the specific mode of its activation is unclear. Although the MET receptors found in human tumor specimens appear highly active, those found on the surface of in vitro-cultured tumor cells are only weakly activated in the absence of exogenous hepatocyte growth factor ligand. Furthermore, pRCC cells cultured in standard two-dimensional conditions with serum fail to respond functionally to MET knockdown or the selective MET inhibitor capmatinib despite clear evidence of kinase inhibition at the molecular level. To better model pRCC in vitro, we developed a three-dimensional coculture system in which renal tumor cells are layered on top of primary fibroblasts in a fashion that mimics the papillary architecture of human tumors. In this three-dimensional spheroid model, the tumor cells survive and proliferate in the absence of serum due to trophic support of hepatocyte growth factor-producing fibroblasts. Unlike tumor cells grown in monoculture, the proliferation of cocultured tumor cells is sensitive to capmatinib and parallels inhibition of MET kinase activity. These findings demonstrate the importance of stromal fibroblasts in pRCC and indicate that accurate in vitro representation of this disease requires the presence of both tumor and fibroblast cells in a structured coculture model.NEW & NOTEWORTHY Two-dimensional monoculture of papillary renal cancer cells fails to replicate several features of the disease found in humans. We hypothesized that this discordance results from lack of trophic support from renal fibroblasts, which are involved in the architecture of human papillary renal tumors. We found that three-dimensional layering of renal cancer cells on top of a fibroblast core using magnetic bioprinting produces a structured spheroid that more faithfully mimics the behavior of human tumors.

Combined Systematic Review and Transcriptomic Analyses of Mammalian Aquaporin Classes 1 to 10 as Biomarkers and Prognostic Indicators in Diverse Cancers

Aquaporin (AQP) channels enable regulated transport of water and solutes essential for fluid homeostasis, but they are gaining attention as targets for anticancer therapies. Patterns of AQP expression and survival rates for patients were evaluated by systematic review (PubMed and Embase) and transcriptomic analyses of RNAseq data (Human Protein Atlas database). Meta-analyses confirmed predominantly negative associations between AQP protein and RNA expression levels and patient survival times, most notably for AQP1 in lung, breast and prostate cancers; AQP3 in esophageal, liver and breast cancers; and AQP9 in liver cancer. Patterns of AQP expression were clustered for groups of cancers and associated with risk of death. A quantitative transcriptomic analysis of AQP1-10 in human cancer biopsies similarly showed that increased transcript levels of AQPs 1, 3, 5 and 9 were most frequently associated with poor survival. Unexpectedly, increased AQP7 and AQP8 levels were associated with better survival times in glioma, ovarian and endometrial cancers, and increased AQP11 with better survival in colorectal and breast cancers. Although molecular mechanisms of aquaporins in pathology or protection remain to be fully defined, results here support the hypothesis that overexpression of selected classes of AQPs differentially augments cancer progression. Beyond fluid homeostasis, potential roles for AQPs in cancers (suggested from an expanding appreciation of their functions in normal tissues) include cell motility, membrane process extension, transport of signaling molecules, control of proliferation and apoptosis, increased mechanical compliance, and gas exchange. AQP expression also has been linked to differences in sensitivity to chemotherapy treatments, suggesting possible roles as biomarkers for personalized treatments. Development of AQP pharmacological modulators, administered in cancer-specific combinations, might inspire new interventions for controlling malignant carcinomas.

Evaluating prognosis by CK7 differentiating renal cell carcinomas from oncocytomas can be used as a promising tool for optimizing diagnosis strategies

Renal Oncocytomas and renal cell carcinomas (RCCs) share a common phenotype. This makes it very difficult to differentiate between the two tumors. Here, this study was to confirmed and expanded the findings that CK7 as a promising tool differentiate RCC from Oncocytomas across various geographic regions. A systematic search of databases was carried out and other relevant articles were also identified. Then the meta-analyses were conducted for 1,711 participants according to the standard guidelines. A total of 21 studies were included on the basis of inclusion criteria. CK7 by IHC was significantly associated with increased diagnosis of RCC (OR=10.64; 95% CI, 7.44-15.23; P=0.0001). Subgroup-analysis showed that findings didn't substantially change when only Caucasians or Asians (OR=10.58; 95% CI, 6.97-16.07; P<0.01 or OR=10.83; 95% CI, 5.39-21.74; P=0.004) were considered. There was also no significant publication bias observed. Our findings provide further evidences that the expression of CK7 contribute to differentiate RCC from Oncocytomas. CK7 protein overexpression was found in RCC, low expression in any of Oncocytomas. CK7 is potentially an important renal tumor marker.

Identification and validation of a 44-gene expression signature for the classification of renal cell carcinomas

BACKGROUND

Renal cancers account for more than 3% of all adult malignancies and cause more than 23,400 deaths per year in China alone. The four most common types of kidney tumours include clear cell, papillary, chromophobe and benign oncocytoma. These histological subtypes vary in their clinical course and prognosis, and different clinical strategies have been developed for their management. Some kidney tumours can be very difficult to distinguish based on the pathological assessment of morphology and immunohistochemistry.

METHODS

Six renal cell carcinoma microarray data sets, including 106 clear cell, 66 papillary, 42 chromophobe, 46 oncocytoma and 35 adjacent normal tissue samples, were subjected to integrative analysis. These data were combined and used as a training set for candidate gene expression signature identification. In addition, two independent cohorts of 1020 RNA-Seq samples from The Cancer Genome Atlas database and 129 qRT-PCR samples from Fudan University Shanghai Cancer Center (FUSCC) were analysed to validate the selected gene expression signature.

RESULTS

A 44-gene expression signature derived from microarray analysis was strongly associated with the histological differentiation of renal tumours and could be used for tumour subtype classification. The signature performance was further validated in 1020 RNA-Seq samples and 129 qRT-PCR samples with overall accuracies of 93.4 and 93.0%, respectively.

CONCLUSIONS

A 44-gene expression signature that could accurately discriminate renal tumour subtypes was identified in this study. Our results may prompt further development of this gene expression signature into a molecular assay amenable to routine clinical practice.

Identification of immune correlates of protection in Shigella infection by application of machine learning

BACKGROUND

Immunologic correlates of protection are important in vaccine development because they give insight into mechanisms of protection, assist in the identification of promising vaccine candidates, and serve as endpoints in bridging clinical vaccine studies. Our goal is the development of a methodology to identify immunologic correlates of protection using the Shigella challenge as a model.

METHODS

The proposed methodology utilizes the Random Forests (RF) machine learning algorithm as well as Classification and Regression Trees (CART) to detect immune markers that predict protection, identify interactions between variables, and define optimal cutoffs. Logistic regression modeling is applied to estimate the probability of protection and the confidence interval (CI) for such a probability is computed by bootstrapping the logistic regression models.

RESULTS

The results demonstrate that the combination of Classification and Regression Trees and Random Forests complements the standard logistic regression and uncovers subtle immune interactions. Specific levels of immunoglobulin IgG antibody in blood on the day of challenge predicted protection in 75% (95% CI 67-86). Of those subjects that did not have blood IgG at or above a defined threshold, 100% were protected if they had IgA antibody secreting cells above a defined threshold. Comparison with the results obtained by applying only logistic regression modeling with standard Akaike Information Criterion for model selection shows the usefulness of the proposed method.

CONCLUSION

Given the complexity of the immune system, the use of machine learning methods may enhance traditional statistical approaches. When applied together, they offer a novel way to quantify important immune correlates of protection that may help the development of vaccines.

Histological and immunohistochemical characterization of feline renal cell carcinoma: a case series

Four feline renal cell carcinomas (RCCs) were examined using histopathological and immunohistochemical procedures. Specimens were classified by predominant histological pattern according to WHO criteria. A panel of antibodies including β-catenin, C-KIT, VEGF and VEGF-R2 and double immunostaining for vimentin/cytokeratin and for E-cadherin/CD10 was selected to characterize the tumors. Neoplasms were classified as tubular (3/4) and papillary (1/4). Neoplastic epithelial cells were cytokeratin, vimentin, E-cadherin, VEGF-R2 positive and C-KIT negative; 3 cases were β-catenin positive, whereas only 2 tumors were CD10 and VEGF positive. No correlation with histotype was evident. Our results confirm the low frequency of RCCs in cats and suggest a histological pattern similar to canine RCCs. In contrast, a peculiar immunohistochemical profile different from both canine and human RCCs is identified.

A Pilot Study Evaluating Fine-Needle Aspiration Cytology of Clear-Cell Renal Cell Carcinoma: Comparison of Ancillary Immunocytochemistry and Cytomorphological Characteristics of SurePath™ Liquid-Based Preparations with Conventional Smears

OBJECTIVE

Fine-needle aspiration cytology (FNAC) based on a liquid-based preparation is a safe and valuable diagnostic tool. However, due to unfamiliarity with this method and the considerably altered morphology that is associated with it, diagnosing renal cell carcinoma (RCC) from this type of preparation remains a challenge for cytopathologists. The aim of this study was to evaluate the cytomorphological characteristics of SurePath™ (SP)-based preparations compared with conventional smear (CS), and also the role of SP-based FNAC in the diagnosis of clear-cell RCC (CRCC), the most common primary renal malignancy.

STUDY DESIGN

Ex vivo FNAC of both tumors and normal renal parenchyma was prepared from 73 cases. Comparative cytomorphological analysis between liquid-based cytology (LBC) and CS as well as Fuhrman nuclear grading (FNG) was carried out. Immunocytochemistry was performed from normal and CRCC cytology specimens.

RESULTS

Normal renal cytology (NRC) showed no significant morphological differences between LBC and CS. For CRCC, LBC showed small, fragmented cell clusters, a 3-dimensional configuration, distinct cytoplasmic vacuoles, and irregular nuclear contours when compared with CS. FNG was overgraded with LBC compared to with CS. AMACR was the most valuable immunocytochemical marker for distinguishing CRCC from NRC.

CONCLUSION

Once cytopathologists become familiar with the altered cytomorphological features of CRCC, FNAC, along with immunocytochemistry, may prove helpful for diagnosis.

Clinicians' Real World Perceptions of Pre-Nephrectomy Diagnostic Biopsy Performance as a Driver of Reduction in Unnecessary Surgeries in Renal Tumors

Operative removal of oncocytomas is generally unnecessary, but not infrequent in the context of renal masses. The infrequent use of pre-nephrectomy biopsies is a function of historical limitations of histopathological differential diagnosis in this setting. Assessment of clinicians’ receptiveness to a novel molecular diagnostic approach to this challenge was undertaken by means of a survey vehicle administered to 102 practicing urologists and pathologists who met inclusion criteria related to their actual clinical activity. Survey results supported the previously reported observations on misdiagnosis with urologists’ reported rates of 25% inconclusive results, and an additional 17% disagree with the final surgical diagnosis. The self-reported rate of 9% for pre-operative biopsies was comparable to prior reports, but 39% of urologists who are not currently performing pre-operative biopsies expressed interest in introducing them into their practice for this purpose with an improved diagnostic. Almost all urologists (94%) felt it important not to resect benign oncocytomas and 62% indicated they would use a test which improved the ability to sub-type renal tumors pre-operatively. The level of performance benchmark of the unidentified prototypic microRNA-based diagnostic as reported previously in the literature was deemed sufficient to change care in these cases by 73%. Overall they predicted a 38% rate of biopsies and resulting increases in decisions to forgo nephrectomy or to perform only partial nephrectomy. Pathologists also expressed support for the use of this technology in the context of inadequate specimens and for improved sub-typing of these tumors in inconclusive cases.

AMACR overexpression as a poor prognostic factor in patients with nasopharyngeal carcinoma

The molecular prognostic adjunct in patients with nasopharyngeal carcinomas (NPCs) still remains obscured. Through data mining from published transcriptomic database, alpha-methylacyl-CoA racemase (AMACR) was first identified as a differentially upregulated gene in NPC tissues, which is a key enzyme for isometric conversion of fatty acids entering the β-oxidation. Given the roles of AMACR in prognostication and frontline therapeutic regimen of common carcinomas, such as prostate cancer, we explored AMACR immunoexpression status and its clinical significance in NPC patients. AMACR immunohistochemistry was retrospectively performed and analyzed using H-score for biopsy specimens from 124 NPC patients who received standard treatment without distant metastasis at initial diagnosis. Those cases with H-score larger than the median value were construed as featuring AMACR overexpression. The findings were correlated with the clinicopathological variables, disease-specific survival (DSS), distant metastasis-free survival (DMFS), and local recurrence-free survival (LRFS). Endogenous AMACR protein expressions were assessed by real-time reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting in NPC cells and non-neoplastic mucosal cells. AMACR overexpression was significantly associated with increment of primary tumor status (P = 0.009) and univariately predictive of adverse outcomes for DSS, DMFS, and LRFS. In the multivariate comparison, AMACR overexpression still remained prognostically independent to portend worse DSS (P = 0.006, hazard ratio = 2.129), DMFS (P = 0.001, hazard ratio = 2.795), and LRFS (P = 0.041, hazard ratio = 2.009), together with advanced American Joint of Cancer Committee (AJCC) stages III-IV. Compared with non-neoplastic cells, both HONE1 and TW01 NPC cells demonstrated markedly increased AMACR expression. AMACR overexpression was identified as an important prognosticator and a potential therapeutic target in the future.

Molecular subtyping of metastatic renal cell carcinoma: implications for targeted therapy

BACKGROUND

Renal cell carcinoma (RCC) is known for its ability to metastasize synchronously or metachronously to various anatomic sites. Distinguishing histologic subtypes of metastatic RCC has become increasingly important, as prognosis and therapy can differ dramatically between subtypes. We propose a combination of immunohistochemistry (IHC) and molecular cytogenetics for subtyping metastatic RCC in light of these potential therapeutic implications.

RESULTS

Specimens from 103 cases of metastatic RCC were retrieved, including 32 cases originally diagnosed as metastatic clear cell renal cell carcinoma (CCRCC), 8 as metastatic papillary renal cell carcinoma (PRCC), and 63 metastatic RCC without a specific subtype. Immunohistochemistry was performed with antibodies against cytokeratin 7 (CK7) and alpha-methylacyl-CoA racemase (AMACR). Dual color interphase fluorescence in situ hybridization was utilized to assess for deletion of chromosome 3p and trisomy of chromosomes 7 and 17 in all tumors. Chromosome 3p deletion was detected in 41% of all metastatic RCC specimens, and trisomy of chromosomes 7 and/or 17 was detected in 16%. Of metastatic CCRCC, chromosome 3p deletion was detected in 63%. Of metastatic PRCC, 75% showed trisomy of chromosomes 7 and/or 17. Of the tumors not previously classified, 6% were positive for CK7, and 64% were positive for AMACR; 35% showed chromosome 3p deletion, and 16% showed trisomy of chromosomes 7 and/or 17. Combined analysis of immunohistochemistry and cytogenetics enabled reclassification of 52% of these metastatic tumors not previously classified.

CONCLUSION

Our findings support the utility of immunohistochemistry and cytogenetics for subtyping metastatic RCC.

Histologic variations and immunohistochemical features of metastatic clear cell renal cell carcinoma

BACKGROUND

Due to advancements in treatment of metastatic and advanced renal cell carcinoma (RCC), it has become increasingly important to diagnose metastatic RCC and the specific subtype. In this study, we investigated the diverse histologic features of metastatic clear cell renal cell carcinoma (CCRCC) cases in comparison with corresponding primary lesions.

METHODS

We identified 119 metastatic CCRCC cases from 81 corresponding primary lesions diagnosed between 1995 and 2010 and evaluated the diverse histologic and immunohistochemical features of these lesions.

RESULTS

A total of 44 primary lesions (54.3%) had a non-clear cell component in addition to a typical clear cell component. Of the 119 metastatic lesions, 63 lesions (52.9%) contained a non-clear cell component, and 29 metastatic lesions were composed of a non-clear cell component only. Rhabdoid features were the most frequent non-clear cell histology among the metastatic lesions. Metastatic CCRCCs mainly showed positive CD10 and epithelial membrane antigen staining and negative cytokeratin 7 staining.

CONCLUSIONS

Metastatic CCRCC commonly showed a variety of histologic features. If there is a difficulty to diagnose metastatic CCRCC due to a variety of histologic features or small biopsy specimen, histologic review of the primary lesion and immunohistochemical analysis can help determine the correct diagnosis.

Development and validation of a microRNA-based diagnostic assay for classification of renal cell carcinomas

Renal cancers account for more than 3% of adult malignancies and cause more than 13,000 deaths per year in the US alone. The four most common types of kidney tumors include the malignant renal cell carcinomas; clear cell, papillary, chromophobe and the benign oncocytoma. These histological subtypes vary in their clinical course and prognosis, and different clinical strategies have been developed for their management. In some kidney tumor cases it can be very difficult for the pathologist to distinguish between tumor types on the basis of morphology and immunohistochemistry (IHC). In this publication we present the development and validation of a microRNA-based assay for classifying primary kidney tumors. The assay, which classifies the four main kidney tumor types, was developed based on the expression of a set of 24 microRNAs. A validation set of 201 independent samples was classified using the assay and analyzed blindly. The assay produced results for 92% of the samples with an accuracy of 95%.

Prognostic value of alpha-methyl CoA racemase (AMACR) expression in renal cell carcinoma

PURPOSE

Alpha-methyl CoA racemase (AMACR) is used as an immunohistochemical marker for renal cell carcinoma (RCC) subtyping to distinguish papillary (pap) RCC. Expression of AMACR in other renal tumor subtypes is inhomogeneous, and the clinical and prognostic value of AMACR is unknown. The aim of this study was to asses AMACR protein expression in different RCC subtypes and to investigate its prognostic significance.

METHODS

Protein expression of AMACR was analyzed in 1,088 renal tumor samples, among them 809 clear cell RCC and 151 papRCC, by immunohistochemistry using tissue microarry (TMA) technique. Results were correlated with clinicopathological data and to follow-up data [overall (OS)/cancer-specific survival (CSS)].

RESULTS

Frequency of AMACR expression was significantly higher in papRCC compared to other tumor subtypes (83% vs. 15-35%, p < 0.0001). Presence of AMACR did not correlate with stage or nodal metastases in papRCC. In a dichotomized scoring (negative vs. positive expression), an inverse correlation between higher grade (p = 0.03) and presence of distant metastasis (p = 0.014) was observed in papRCC. AMACR expression correlated with the presence of nodal metastasis in ccRCC (p = 0.02). Both in ccRCC and in papRCC, OS and CSS did not correlate with the AMACR expression status.

CONCLUSIONS

The high expression in papRCC confirms AMACR to be a marker for subtype differentiation in RCC, while a missing expression in this subtype seems to be associated with negative pathological features. However, in contrast to other tumor entities, AMACR expression seems to have a limited prognostic impact in renal carcinoma, especially with regard to survival.

Molecular sub-classification of renal epithelial tumors using meta-analysis of gene expression microarrays

PURPOSE

To evaluate the accuracy of the sub-classification of renal cortical neoplasms using molecular signatures.

EXPERIMENTAL DESIGN

A search of publicly available databases was performed to identify microarray datasets with multiple histologic sub-types of renal cortical neoplasms. Meta-analytic techniques were utilized to identify differentially expressed genes for each histologic subtype. The lists of genes obtained from the meta-analysis were used to create predictive signatures through the use of a pair-based method. These signatures were organized into an algorithm to sub-classify renal neoplasms. The use of these signatures according to our algorithm was validated on several independent datasets.

RESULTS

We identified three Gene Expression Omnibus datasets that fit our criteria to develop a training set. All of the datasets in our study utilized the Affymetrix platform. The final training dataset included 149 samples represented by the four most common histologic subtypes of renal cortical neoplasms: 69 clear cell, 41 papillary, 16 chromophobe, and 23 oncocytomas. When validation of our signatures was performed on external datasets, we were able to correctly classify 68 of the 72 samples (94%). The correct classification by subtype was 19/20 (95%) for clear cell, 14/14 (100%) for papillary, 17/19 (89%) for chromophobe, 18/19 (95%) for oncocytomas.

CONCLUSIONS

Through the use of meta-analytic techniques, we were able to create an algorithm that sub-classified renal neoplasms on a molecular level with 94% accuracy across multiple independent datasets. This algorithm may aid in selecting molecular therapies and may improve the accuracy of subtyping of renal cortical tumors.

Orthotopic xenografts of RCC retain histological, immunophenotypic and genetic features of tumours in patients

Renal cell carcinoma (RCC) is an aggressive malignancy with limited responsiveness to existing treatments. In vivo models of human cancer, including RCC, are critical for developing more effective therapies. Unfortunately, current RCC models do not accurately represent relevant properties of the human disease. The goal of this study was to develop clinically relevant animal models of RCC for preclinical investigations. We transplanted intact human tumour tissue fragments orthotopically in immunodeficient mice. The xenografts were validated by comparing the morphological, phenotypic and genetic characteristics of the kidney tumour tissues before and after implantation. Twenty kidney tumours were transplanted into mice. Successful tumour growth was detected in 19 cases (95%). The histopathological and immunophenotypic features of the xenografts and those of the original tumours largely overlapped in all cases. Evaluation of genetic alterations in a subset of 10 cases demonstrated that the grafts largely retained the genetic features of the pre-implantation RCC tissues. Indeed, primary tumours and corresponding grafts displayed identical VHL mutations. Moreover, an identical pattern of DNA copy amplification or loss was observed in 6/10 cases (60%). In summary, orthotopic engrafting of RCC tissue fragments can be successfully used to generate animal models that closely resemble RCC in patients. These models will be invaluable for in vivo preclinical drug testing and for deeper understanding of kidney carcinogenesis. The raw data of the SNP array analysis has been submitted to the GEO database (Accession No. GSE29062).

What can molecular pathology contribute to the management of renal cell carcinoma?

The incidence of renal cell carcinoma (RCC) is increasing and outcomes remain poor. One-third of patients with localized disease will relapse, and 5-year survival for patients with metastatic disease is less than 10%. No molecular test is currently available to identify which patients who have undergone 'curative' surgery will relapse, and which patients will respond to targeted therapy. Some well characterized biochemical pathways, such as those associated with von Hippel-Lindau disease, are aberrantly regulated in RCC and are associated with histological subtype, but the understanding of these pathways contributes little to the clinical management of patients with RCC. Gene expression and sequencing studies have increased our understanding of the genetic basis of the disease but have failed to establish any unified classification to improve molecular stratification or to predict which patients are likely to relapse or respond to targeted therapy. Instead, they have served to highlight that RCC is heterogeneous at histological, morphological, and molecular levels, and that novel approaches are required to resolve the complexity of RCC prognostication and prediction of treatment response.

Accurate molecular classification of renal tumors using microRNA expression

Subtypes of renal tumors have different genetic backgrounds, prognoses, and responses to surgical and medical treatment, and their differential diagnosis is a frequent challenge for pathologists. New biomarkers can help improve the diagnosis and hence the management of renal cancer patients. We extracted RNA from 71 formalin-fixed paraffin-embedded (FFPE) renal tumor samples and measured expression of more than 900 microRNAs using custom microarrays. Clustering revealed similarity in microRNA expression between oncocytoma and chromophobe subtypes as well as between conventional (clear-cell) and papillary tumors. By basing a classification algorithm on this structure, we followed inherent biological correlations and could achieve accurate classification using few microRNAs markers. We defined a two-step decision-tree classifier that uses expression levels of six microRNAs: the first step uses expression levels of hsa-miR-210 and hsa-miR-221 to distinguish between the two pairs of subtypes; the second step uses either hsa-miR-200c with hsa-miR-139-5p to identify oncocytoma from chromophobe, or hsa-miR-31 with hsa-miR-126 to identify conventional from papillary tumors. The classifier was tested on an independent set of FFPE tumor samples from 54 additional patients, and identified correctly 93% of the cases. Validation on qRT-PCR platform demonstrated high correlation with microarray results and accurate classification. MicroRNA expression profiling is a very effective molecular bioassay for classification of renal tumors and can offer a quantitative standardized complement to current methods of tumor classification.

Strength of molecular cytogenetic analyses for adjusting the diagnosis of renal cell carcinomas with both clear cells and papillary features: a study of three cases

Histological features are usually sufficient for providing an accurate diagnosis of renal cell carcinomas (RCC). However, the morphological appearance might sometimes be misleading. For instance, RCC with papillary areas and extensive clear cell changes may be difficult to classify either as clear cell renal carcinoma or as papillary renal cell carcinoma (pRCC). We used the combination of immunohistochemistry, conventional cytogenetics, fluorescence in situ hybridization (FISH), bacterial artificial chromosomes comparative genomic hybridization arrays and high-density single nucleotides polymorphism arrays (SNP arrays) to characterize three cases of RCC showing a predominant cytology of cells with clear cytoplasm and variable amounts of papillary areas. In accordance with the 2004 World Health Organization (WHO) classification, we initially assessed the diagnosis of clear cell RCC for one of the cases and unclassified RCC for the two remaining cases. However, because of a strong immunohistochemical labeling for alpha-methylacyl-CoA racemase, as well as the presence of a gain of chromosomes 7 and 17, we concluded that two of these tumors were actually pRCC. As for the third case, because of the presence of both pCCR and ccCCR molecular cytogenetic aberrations, including gains of chromosomes 7 and 17, loss of chromosome Y and whole chromosome 3 loss of heterozyosity (isodisomy), the final diagnosis was hybrid tumor cc-pRCC, so-called "unclassified RCC" according to the WHO classification. Our observations demonstrate the necessity to use immunohistochemical and cytogenetic tools in all cases of RCC showing unusual features. The combination of FISH and SNP arrays is prevailing for characterizing cases with hybrid features.

Determination of angptl4 mRNA as a diagnostic marker of primary and metastatic clear cell renal-cell carcinoma

Background

We have previously shown that angiopoietin-like 4 (angptl4) mRNA, a hypoxia-inducible gene, is highly expressed in clear cell renal-cell carcinoma (ccRCC), the most common subtype of RCC for which no specific marker is available. We here investigated whether angptl4 mRNA 1) could be a useful diagnostic and/or prognostic marker of ccRCC in a large and comprehensive retrospective series, 2) induction is dependent on the VHL status of tumors.

Methodology/Principal Findings

Using in situ hybridization, we report that angptl4 mRNA is expressed in 100% of both sporadic (n = 102) and inherited (n = 6) primary ccRCCs, without any statistical association with nuclear grade (p = 0.39), tumor size (p = 0.09), stage grouping (p = 0.17), progression-free survival (p = 0.94), and overall survival (p = 0.80). Angptl4 mRNA was also expressed in 26 (87%) of 30 secondary ccRCCs but neither in any other secondary RCCs (n = 7). In contrast, angptl4 mRNA was neither expressed in 94% non-ccRCC renal tumors (papillary RCCs (n = 46), chromophobe RCCs (n = 28), and oncocytomas (n = 9)), nor in non-renal clear cell carcinomas (n = 39). Angptl4 expression was also examined in tumors associated (n = 23) or not associated (n = 66) with VHL disease. 40 (98%) hemangioblastomas expressed angptl4 whereas all pheochromocytomas (n = 23) and pancreatic tumors (n = 25) were angptl4-negative, whatever their VHL status.

Conclusions/Significance

Angptl4 mRNA expression was highly associated with ccRCC (p = 1.5 10⁻⁴⁹, Chi square test) allowing to define its expression as a diagnosis marker for primary ccRCC. Moreover, angptl4 mRNA allows to discriminate the renal origin of metastases of clear-cell carcinomas arising from various organs. Finally, inactivation of VHL gene is neither necessary nor sufficient for angptl4 mRNA induction.

Sinonasal renal cell-like adenocarcinoma: a report on four patients

BACKGROUND

We have described an unusual sinonasal neoplasm which is a histological mimic of renal cell carcinoma (RCC) and coined the nosological classification "sinonasal renal cell-like adenocarcinoma" (SRCLA) to describe this unusual entity. Since the original description (Zur et al. Otolaryngol Head Neck Surg 128:441-7, 2002), we have reviewed the case reported by Moh'd Hadi et al. (Rhinology 40:44-7, 2002) and have seen two new cases in consultation. Our purpose here is to describe the additional cases and to extend the reported outcome for these patients.

DESIGN

Four patients were identified. Slides and immunohistochemistry results were reviewed in consultation. Updated clinical follow-up was obtained from the respective clinicians.

RESULTS

This group consisted of three women, one man, 22-69 years, and mean 46. Three tumors were in the nasal cavity and one was in the nasopharynx. Histologically, these tumors were uniformly composed of clear cells, forming either solid or glandular patterns. The tumor cells were cuboidal to polyhedral; transition to short spindle cells was seen in one case. One case revealed moderate nuclear pleomorphism. No perineural or vascular invasion, or necrosis was seen. No mucin-producing or squamous elements were seen. Immunohistochemistry (IHC) revealed the following staining profile: CK7 + (4/4), CK20 + (focal 1/4), S100 + (1/4), and CD10 + (1/2). No staining was seen for vimentin (0/4), RCC (0/2), thyroglobulin (0/2), actin (0/2), or calponin (0/2). Three patients were treated primarily with surgery, two patients also received adjuvant radiotherapy (RT); the fourth patient was treated with primary RT. All patients are disease-free, based on endoscopy and/or radiography, 2, 4, 5 and 8 years after diagnosis. Renal cell carcinoma has not been identified in any patient.

CONCLUSION

Sinonasal renal cell-like adenocarcinoma is a rare and distinct entity noteworthy in its resemblance to RCC. Immunohistochemistry can easily distinguish between these two tumors. No patient developed recurrent or metastatic disease, or was found to have RCC. Greater experience will allow us to fully understand its long-term behavior and arrive at more standardized therapeutic recommendations.