Molecular cytogenetics of renal cell tumors

The utilization of single-cell sequencing technology in investigating the immune microenvironment of ccRCC

The growth and advancement of ccRCC are strongly associated with the presence of immune infiltration and the tumor microenvironment, comprising tumor cells, immune cells, stromal cells, vascular cells, myeloid-derived cells, and extracellular matrix (ECM). Nevertheless, as a result of the diverse and constantly evolving characteristics of the tumor microenvironment, prior advanced sequencing methods have frequently disregarded specific less prevalent cellular traits at varying intervals, thereby concealing their significance. The advancement and widespread use of single-cell sequencing technology enable us to comprehend the source of individual tumor cells and the characteristics of a greater number of individual cells. This, in turn, minimizes the impact of intercellular heterogeneity and temporal heterogeneity of the same cell on experimental outcomes. This review examines the attributes of the tumor microenvironment in ccRCC and provides an overview of the progress made in single-cell sequencing technology and its particular uses in the current focus of immune infiltration in ccRCC.

Epigenomic charting and functional annotation of risk loci in renal cell carcinoma

While the mutational and transcriptional landscapes of renal cell carcinoma (RCC) are well-known, the epigenome is poorly understood. We characterize the epigenome of clear cell (ccRCC), papillary (pRCC), and chromophobe RCC (chRCC) by using ChIP-seq, ATAC-Seq, RNA-seq, and SNP arrays. We integrate 153 individual data sets from 42 patients and nominate 50 histology-specific master transcription factors (MTF) to define RCC histologic subtypes, including EPAS1 and ETS-1 in ccRCC, HNF1B in pRCC, and FOXI1 in chRCC. We confirm histology-specific MTFs via immunohistochemistry including a ccRCC-specific TF, BHLHE41. FOXI1 overexpression with knock-down of EPAS1 in the 786-O ccRCC cell line induces transcriptional upregulation of chRCC-specific genes, TFCP2L1, ATP6V0D2, KIT, and INSRR, implicating FOXI1 as a MTF for chRCC. Integrating RCC GWAS risk SNPs with H3K27ac ChIP-seq and ATAC-seq data reveals that risk-variants are significantly enriched in allelically-imbalanced peaks. This epigenomic atlas in primary human samples provides a resource for future investigation.

Long Non-Coding RNAs as Novel Biomarkers in the Clinical Management of Papillary Renal Cell Carcinoma Patients: A Promise or a Pledge?

Papillary renal cell carcinoma (pRCC) represents the second most common subtype of renal cell carcinoma, following clear cell carcinoma and accounting for 10-15% of cases. For around 20 years, pRCCs have been classified according to their mere histopathologic appearance, unsupported by genetic and molecular evidence, with an unmet need for clinically relevant classification. Moreover, patients with non-clear cell renal cell carcinomas have been seldom included in large clinical trials; therefore, the therapeutic landscape is less defined than in the clear cell subtype. However, in the last decades, the evolving comprehension of pRCC molecular features has led to a growing use of target therapy and to better oncological outcomes. Nonetheless, a reliable molecular biomarker able to detect the aggressiveness of pRCC is not yet available in clinical practice. As a result, the pRCC correct prognosis remains cumbersome, and new biomarkers able to stratify patients upon risk of recurrence are strongly needed. Non-coding RNAs (ncRNAs) are functional elements which play critical roles in gene expression, at the epigenetic, transcriptional, and post-transcriptional levels. In the last decade, ncRNAs have gained importance as possible biomarkers for several types of diseases, especially in the cancer universe. In this review, we analyzed the role of long non-coding RNAs (lncRNAs) in the prognosis of pRCC, with a particular focus on their networking. In fact, in the competing endogenous RNA hypothesis, lncRNAs can bind miRNAs, resulting in the modulation of the mRNA levels targeted by the sponged miRNA, leading to additional regulation of the target gene expression and increasing complexity in the biological processes.

Multitarget fluorescence in situ hybridization diagnostic applications in solid and hematological tumors

Introduction: Multitarget FISH (mFISH) is a technique allowing for simultaneous detection of multiple targets sequences on the same slide through the choice of spectrally distinct fluorophore labels. The mFISH could represent a useful tool in the field of precision oncology.Areas covered: This review discusses the potential applications of mFISH technology in the molecular diagnosis of different solid and hematological tumors, including non-small cell lung cancers, melanomas, renal cell carcinomas, bladder carcinomas, germ cell tumors, and multiple myeloma, as commonly required in the clinical practice.Expert Opinion: In this emerging era of the tailored therapies and newer histo-molecular classifications, there are increasing numbers of predictive and diagnostic biomarkers required for effective clinical care. The mFISH approach may have several applications in the common clinical practice, improving the molecular diagnosis in terms of time, cost and preservation of biomaterial for tumors with a limited amount of tumor available. The mFISH provides several advantages compared to other high-throughput technologies; however, it requires high level of expertise required to interpret complex results.

Multifocal Renal Cell Carcinomas With Somatic IDH2 Mutation: Report of a Previously Undescribed Neoplasm

Renal cell carcinoma (RCC) is a heterogenous disease composed of several different cancer types characterized by distinct histologies and genetic alterations, including mutation of the Krebs cycle enzyme genes for fumarate hydratase and succinate dehydrogenase (SDH). This report describes a patient with multifocal renal tumors that presented with a novel, biphasic histologic morphology with one component consisting of small cells growing in a diffuse pattern occasionally forming glandular and cystic structures, reminiscent of type 1 papillary RCC, and the other component having larger cells with abundant eosinophilic and clear cytoplasm and appearing in a solid pattern of growth. Genetic analysis of multiple tumors showed that all had a somatic mutation of the IDH2 gene that created the known pathogenic, gain-of-function p.R172M alteration that results in abnormal accumulation of the oncometabolite 2-hydroxyglutarate (2-HG). Analysis of multiple tumors demonstrated highly elevated levels of 2-HG and a CpG island methylator phenotype that is characteristic of 2-HG-related inhibition of the Ten-eleven translocation (TET) family of DNA demethylases. In combination with fumarate hydratase-deficient and succinate dehydrogenase-deficient RCCs that have increased levels of the fumarate and succinate oncometabolites, respectively, the mutation of isocitrate dehydrogenase 2 represents the third Krebs cycle enzyme alteration to be associated with oncometabolite-induced RCC tumorigenesis. This study associates the discovery of a new histologic presentation of RCC with the first report of an IDH2 gain-of-function mutation in RCC.

Papillary Renal Cell Carcinoma (PRCC): An Update

Papillary renal cell carcinoma (PRCC) is the second most common type of renal carcinoma following clear cell renal cell carcinoma. Papillary renal cell carcinoma is usually divided histologically into 2 types namely, type 1 and type 2. This classification, however, is unsatisfactory as many of papillary carcinoma are unclassifiable by the existing criteria. In recent years there has been a remarkable progress in our understanding of the molecular basis of PRCC. These studies have revealed that type 2 PRCCs represent a heterogenous group which may be subdivided into additional subtypes based on the genetic and molecular make up of these tumors and reflecting different clinical course and prognosis. Some of the molecular features such a hypermethylation of CPG islands in the promotor regions of genes and over expression of the antioxidant pathways within tumor cells have been recognized as markers of poor prognosis. Targeted therapies for papillary carcinoma in the past have been unsuccessful because of lack of clear understanding of the molecular basis of these tumors. It is hoped that recent progress in our understanding of the pathogenesis of various subtypes of PRCC, effective targeted therapies will eventually emerge in due course.

Recalling Cohnheim's Theory: Papillary Renal Cell Tumor as a Model of Tumorigenesis from Impaired Embryonal Differentiation to Malignant Tumors in Adults

We have suggested that papillary renal cell tumor (PRCT) of the kidney arises from nephrogenic rest-like lesions. To approve our hypothesis, we worked up 14 kidneys bearing papillary and 14 ones with conventional renal cell carcinoma (CRCC) histologically and found 42 papillary lesions in average per kidney bearing PRCT. PRCTs are characterized by loss of the Y chromosome and trisomy of chromosomes 7 and 17. The MET and HNF1B are localized to chromosome 7q31 and 17q21 and are frequently amplified in PRCT. We have analyzed the expression of the mutant MET in hereditary PRCTs and precursor lesions and found duplication and expression of the mutated allele. Because both genes are involved in early stage of nephron development, we have analyzed the expression of MET and HNF1B by immunohistochemistry in fetal kidneys, precursor lesions and PRCTs. We detected strong expression of MET and HNF1B in distal compartment of S-shaped body of fetal kidneys and in nephrogenic rest-like precursor lesions. Our finding suggests an association between expression of MET and HNF1B in precursor lesions and development of PRCT. We propose a model involving chromosomal clonal evolution and corresponding gene expression for development of PRCTs from embryonic rests due to impaired differentiation. Our model suggests that PRCT have a natural history distinct from that of most common CRCC.

Diagnosis of Chromophobe Renal Cell Carcinoma by Chromosomal Analysis

Chromophobe renal cell carcinoma may pose a differential diagnostic problem by routine histologic examination because it may be misdiagnosed as another type of renal cancer with a totally different clinical behavior. A low DNA content as well as hypodiploidy seem to be associated with this renal tumor subtype. We report a case in which the cytogenetic report was of great value for a correct histologic diagnosis.

Mutations in the Mitochondrial ND1 Gene Are Associated with Postoperative Prognosis of Localized Renal Cell Carcinoma

We analyzed mutations in the mitochondrial ND1 gene to determine their association with clinicopathological parameters and postoperative recurrence of renal cell carcinoma (RCC) in Japanese patients. Among 62 RCC cases for which tumor pathology was confirmed by histopathology, ND1 sequencing revealed the presence of 30 mutation sites in 19 cases. Most mutations were heteroplasmic, with 16 of 19 cases harboring one or more heteroplasmic sites. Additionally, 12 sites had amino acid mutations, which were frequent in 10 of the cases. The 5-year recurrence-free survival (RFS) rate was significantly worse in patients with tumors >40 mm in diameter (p = 0.0091), pathological T (pT) stage ≥3 (p = 0.0122), Fuhrman nuclear atypia grade ≥III (p = 0.0070), and ND1 mutations (p = 0.0006). Multivariate analysis using these factors revealed that mutations in ND1 were significantly associated with the 5-year RFS rate (p = 0.0044). These results suggest a strong correlation between the presence of ND1 mutations in cancer tissue and postoperative recurrence of localized RCC in Japanese patients.

An integrative and comparative study of pan-cancer transcriptomes reveals distinct cancer common and specific signatures

To investigate the commonalities and specificities across tumor lineages, we perform a systematic pan-cancer transcriptomic study across 6744 specimens. We find six pan-cancer subnetwork signatures which relate to cell cycle, immune response, Sp1 regulation, collagen, muscle system and angiogenesis. Moreover, four pan-cancer subnetwork signatures demonstrate strong prognostic potential. We also characterize 16 cancer type-specific subnetwork signatures which show diverse implications to somatic mutations, somatic copy number aberrations, DNA methylation alterations and clinical outcomes. Furthermore, some of them are strongly correlated with histological or molecular subtypes, indicating their implications with tumor heterogeneity. In summary, we systematically explore the pan-cancer common and cancer type-specific gene subnetwork signatures across multiple cancers, and reveal distinct commonalities and specificities among cancers at transcriptomic level.

Sciellin is a marker for papillary renal cell tumours

There are no adequate immunohistochemical markers for papillary renal cell tumours. The aim of this study was to establish a gene expression profile of papillary renal cell tumours using an expression microarray approach. Through hierarchical clustering and significant analysis of microarrays, we have selected the best 13 genes and analysed their expression by real-time polymerase chain reaction (RT-PCR). Of these genes, we selected SCEL as potential marker of interest. Immunohistochemical staining of tissue microarrays containing all major types of kidney cancers revealed positive staining for sciellin in 87 of 114 papillary renal cell tumours and in 13 of 19 precursor lesions. No other renal tumour types were positive for sciellin. Our study indicates that although not all tumours express sciellin, its expression may help to confirm the diagnosis papillary renal cell tumour.

The MET Inhibitor AZD6094 (Savolitinib, HMPL-504) Induces Regression in Papillary Renal Cell Carcinoma Patient-Derived Xenograft Models

PURPOSE

Papillary renal cell carcinoma (PRCC) is the second most common cancer of the kidney and carries a poor prognosis for patients with nonlocalized disease. The HGF receptor MET plays a central role in PRCC and aberrations, either through mutation, copy number gain, or trisomy of chromosome 7 occurring in the majority of cases. The development of effective therapies in PRCC has been hampered in part by a lack of available preclinical models. We determined the pharmacodynamic and antitumor response of the selective MET inhibitor AZD6094 in two PRCC patient-derived xenograft (PDX) models.

EXPERIMENTAL DESIGN

Two PRCC PDX models were identified and MET mutation status and copy number determined. Pharmacodynamic and antitumor activity of AZD6094 was tested using a dose response up to 25 mg/kg daily, representing clinically achievable exposures, and compared with the activity of the RCC standard-of-care sunitinib (in RCC43b) or the multikinase inhibitor crizotinib (in RCC47).

RESULTS

AZD6094 treatment resulted in tumor regressions, whereas sunitinib or crizotinib resulted in unsustained growth inhibition. Pharmacodynamic analysis of tumors revealed that AZD6094 could robustly suppress pMET and the duration of target inhibition was dose related. AZD6094 inhibited multiple signaling nodes, including MAPK, PI3K, and EGFR. Finally, at doses that induced tumor regression, AZD6094 resulted in a dose- and time-dependent induction of cleaved PARP, a marker of cell death.

CONCLUSIONS

Data presented provide the first report testing therapeutics in preclinical in vivo models of PRCC and support the clinical development of AZD6094 in this indication.

Understanding pathologic variants of renal cell carcinoma: distilling therapeutic opportunities from biologic complexity

CONTEXT

Once believed to represent a uniform malignant phenotype, renal cell carcinoma (RCC) is now viewed as a diverse group of cancers that arise from the nephron.

OBJECTIVE

To review the pathologic characteristics, clinical behavior, molecular biology, and systemic therapy options of recognized RCC histologic subtypes.

EVIDENCE ACQUISITION

A systematic review of English-language articles was performed using the Medline and Web of Science databases. Manuscripts were selected with consensus of the coauthors and evaluated using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) criteria.

EVIDENCE SYNTHESIS

The major findings of the evaluated manuscripts are discussed with an emphasis on the description of the pathologic features, clinical behavior, prognosis, and therapeutic strategies.

CONCLUSIONS

Classification schemes for kidney cancer have undergone dramatic changes over the past two decades. Improvements in these classification schemes are important, as pathologic variants differ not only in disease biology, but also in clinical behavior, prognosis, and response to systemic therapy. In the era of genomic medicine, further refinements in characterization of RCC subtypes will be critical to the progress of this burgeoning clinical space.

PATIENT SUMMARY

Kidney cancer can be subdivided into related but different cancers that arise from the kidney's tubules. In this article we review current classifications for kidney cancer, discuss their characteristics, and provide an overview of each subtype's clinical behavior and treatment. We stress that each subtype harbors unique biology and thus responds differently to available treatment strategies.

Foretinib (XL880): c-MET inhibitor with activity in papillary renal cell cancer

Papillary renal cell cancer (RCC) constitutes approximately 10 % of renal cancers and is the commonest form after clear cell RCC, which accounts for approximately 75 % of cases. Until recently, most clinical trials in RCC were open to patients of all histologic types. Very recent clinical trials have been performed predominately in patients with clear cell RCC and relatively few trials have been done for patients with papillary RCC. The clinical characteristics of papillary RCC are less well appreciated because of both its relative rarity in the general oncology population and the lack of related clinical studies. This article reviews papillary RCC as a clinical entity separate from clear cell RCC. The MET signaling pathway, its association with increased invasion and progression of human cancer, and its dysregulation in papillary RCC is discussed. Lastly, foretinib, a multitargeted receptor tyrosine kinase inhibitor of several receptors, including MET and vascular endothelial growth factor receptor 2, is described in preclinical and phase I studies as well as in a phase II study in papillary RCC patients.

Expression of KRT7 and WT1 differentiates precursor lesions of Wilms' tumours from those of papillary renal cell tumours and mucinous tubular and spindle cell carcinomas

Wilms' tumours (WT) and adult papillary renal cell tumours (pRCT) are associated with precursor lesions of embryonic origin. The aim of this study was to analyse the expression of WT1, KRT7, KRT8, KRT18 and KRT19 genes by immunohistochemistry in 74 precursor lesions associated with WTs, pRCTs and mucinous tubular and spindle cell carcinomas (MTSCC). All precursor lesions associated with Wilms' tumours were positive for WT1, whereas all precursor lesions in pRCT and MTSCC-bearing kidneys were negative. None of the WT-associated lesions were positive for KRT7, but 69-80% of lesions associated with pRCTs and MTSCCs were positive for KRT7. KRT8, KRT18 and KRT19 were found to be expressed in 80-100% of all types of precursor lesions. Our findings indicate that the precursor lesions analysed in this study are committed in an early stage of cellular differentiation to the development of either Wilms' tumours or papillary RCTs and MTSCCs.

Investigation of recurrent deletion loci specific to conventional renal cell carcinoma by comparative allelotyping in major epithelial carcinomas

OBJECTIVE

Loss of heterozygosity (LOH) studies were undertaken to investigate the consistently deleted loci/? tumor suppressor gene loci (TSG) on 3p in conventional renal cell carcinoma (cRCC).

MATERIALS AND METHODS

LOH studies were performed by polymerase chain reaction (PCR) using 15 micro satellite markers mapped in region 3p12-p26 on 40 paired cRCC tumors and normal kidney at Stages I-IV. Simultaneously, fluorescent in-situ hybridization (FISH) studies were performed to investigate the allelic deletion of fragile histidine triad (FHIT).

RESULTS

Our studies revealed three affected regions; 3p12.2-p14.1, 3p14.2-p21.1, and 3p24.2-p26.1 with differential frequencies in Group I (Stage I and II) and Group II (Stage III and IV). Incidence for D3S1234 (FHIT locus) and D3S2454 (3p13) was 75% and 83% in Group I and II, respectively. Comparative allelotyping in epithelial malignancies like lung, bladder, and breast tumors revealed LOH (frequency 14-20%) only in breast tumors for D3S2406, D3S1766 (distal to FHIT), and D3S1560 (distal to VHL, Von-Hippal Lindau). FISH using FHIT gene probe revealed deletions in cRCC (88%), breast (30%), and lung tumors (10%) with no deletions in bladder tumors and leukemias, signifying the importance of FHIT in the pathogenesis of tumors of epithelial origin.

CONCLUSION

Our findings suggested FHIT deletion as an early and VHL deletion as an early and/or late event in cRCC. Additionally, studies also disclosed the recurrent deletions of flanking loci to FHIT and VHL in cRCC. The dilemma of interstitial or continuous deletion on 3p needs to be resolved by implementation of latest sensitive molecular techniques that would further help to narrow down search for TSG loci specific to cRCC, other than VHL and FHIT.

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).

Tumor biology and prognostic factors in renal cell carcinoma

In the past 15 years, there has been an increased understanding of the tumor biology of renal cell carcinoma (RCC). The identification of vascular endothelial growth factor (VEGF), its related receptor (VEGFR), and the mammalian target of rapamycin as dysregulated signaling pathways in the development and progression of RCC has resulted in the rational development of pharmaceutical agents capable of specifically targeting key steps in these pathways. Clinical trials have demonstrated survival benefit with these agents, particularly in clear cell RCC patients. However, metastatic RCC will progress in all patients, resulting in a critical need to determine patient risk and optimize treatment. The goal of this article is to highlight the significant breakthroughs made in understanding the critical genetic alterations and signaling pathways underlying the pathogenesis of RCC. The discovery of prognostic factors and development of comprehensive nomograms to stratify patient risk and predictive biomarkers to facilitate individualized treatment selection and predict patient response to therapy also are reviewed.

Molecular pathology of renal oncocytoma: a review

Differentiating renal oncocytoma from its renal cell carcinoma (RCC) mimics, particularly chromophobe RCC, can be difficult, especially when limited tissue is available for evaluation and requires sophisticated microscopic, ultrastructural and immunohistochemical evaluation. In this review, the relevant literature has been reviewed, and supporting data obtained by applying modern microarray-based technologies are discussed with a focus on molecular pathology of renal oncocytoma. The high resolution whole-genome DNA-microarray based analyses excluded with all certainty the occurrence of small specific alterations. Renal oncocytomas are characterized by variable chromosomal patterns. The number of genes selected by global gene expression analyses and their usefulness in the diagnostic pathology based on immunohistochemical evaluation is far below the expectations. The conflicting staining patterns, together with the poor specificity of proposed antibodies, leads us to believe that these candidate immunomarkers might not help in the separation of these tumors. Applying DNA based tools might help in the diagnosis of renal oncocytoma with uncertain histology. However, only the combination of all available techniques could give reliable information.

Renal cell carcinoma

Renal Cell Carcinoma (RCC) has the highest mortality rate of the genitourinary cancers and the incidence of RCC has risen steadily. If detected early, RCC is curable by surgery although a minority are at risk of recurrence. Increasing incidental detection and an ageing population has led to active surveillance as an option for patients with small renal masses. RCC is heterogeneous and comprises several histological cell types with different genetics, biology and behavior. The identification of the genes predisposing to inherited syndromes with RCC has provided much of our knowledge of the molecular basis of early sporadic RCC. Many of the oncogenes and tumor suppressor genes that are mutated leading to pathway dysregulation in RCC remain to be elucidated. Global studies of copy number, gene sequencing, gene expression, miRNA expression and gene methylation in primary RCC will lead towards this goal. The natural history of RCC indicated by candidate precursor lesions, multifocal or bilateral disease, growth rate of small renal masses under surveillance, and high risk populations provide insight into the behavior of this disease. The use of molecular markers for early detection and prognosis merits more attention with ongoing advances in omics technologies. This review focuses on early RCC, that is disease confined within the renal capsule.

The clinical implications of the genetics of renal cell carcinoma

Over the last several decades, the advances in molecular genetics have elucidated kidney cancer gene pathways. Kidney cancer is a heterogeneous disorder. Each specific type of kidney cancer has its own histologic features, gene, and clinical course. Insight into the genetic basis of kidney cancer has been learned largely from the study of the familial or hereditary forms of kidney cancer. Extirpative surgery is currently the treatment of choice for kidney cancer that is confined to the kidney. Treatment for advanced or metastatic kidney cancer is a formidable challenge with the traditional therapies currently available. However, investigation of the Mendelian single-gene syndromes, like von Hippel Lindau (VHL: VHL gene), hereditary papillary renal carcinoma (HPRC: c-Met gene), Birt-Hogg-Dubé (BHD: BHD gene), and hereditary leiomyomatosis renal cell cancer (HLRCC: fumarate hydratase gene) provides an opportunity to develop pathway specific therapies. Advances in molecular therapeutics offer novel treatment options for patients with advanced disease.

Trisomy 7 and 17 mark papillary renal cell tumours irrespectively of variation of the phenotype

BACKGROUND

Papillary renal cell tumours (RCTs) have been described as a genetic entity. Recently, papillary RCTs have been divided into small (type 1) and large (type 2) cell tumours. Subsequent DNA analyses have resulted in controversial data regarding putative genetic changes marking type 1 and type 2 tumours.

AIM

The aim of this study was to improve the original description that papillary RCT is a genetic entity regardless of the phenotypic variation.

METHODS

DNA from 163 papillary RCTs, including 82 multiplex tumours from eight hereditary cases, was analysed for copy number changes by chromosomal comparative genomic hybridisation (CGH) and/or for allelic changes at chromosomes 7 and 17 by microsatellite analysis. The results of the genetic analysis were compared with the cytological characteristics of the tumours.

RESULTS

The results showed alterations of chromosomes 7 and 17 at similar frequencies in papillary RCTs with characteristics ranging from small to large cell, nuclear grade 1 to 3, and 3 mm to 16 cm diameter.

CONCLUSION

Trisomies of chromosomes 7 and 17 are specific genetic alterations in papillary RCTs irrespective of their size, grade and cellular differentiation.

Three genetic developmental stages of papillary renal cell tumors: duplication of chromosome 1q marks fatal progression

Papillary renal cell tumors (RCT) make up a cytomorphologically and biologically heterogeneous group of kidney cancers including renal cell adenomas (RCA) and renal cell carcinomas (RCC). To find genetic markers landmarking the tumor progression, we have evaluated the genetic alterations obtained by karyotyping, chromosomal and array-CGH and compared with the cytological characteristics and biological behavior of 60 papillary RCTs. Based on the genetic and clinical data, we have separated 3 groups of tumors and proposed 3 genetically defined developmental stages of papillary RCTs. Papillary RCAs are characterized by combined trisomy of chromosomes 7 and 17, whereas papillary RCCs displayed additional trisomies of 3q, 8q, 12q, 16q and 20q. In addition to the genetic changes occurring in the second group, the third group of tumors was characterized by 1q gain and 6q, 8p, 9p and 14q losses. Kaplan-Meier analysis revealed a significant association between chromosome 1q gain and deadly outcome of the disease. The cytomorphological variation and size of tumors in the second and third groups did not correlate with the clinical outcome. Therefore, we suggest that our genetic classification system landmarking papillary RCA, papillary RCC without and with progression offer a better system to characterize the tumor biology of clinical significance than a cellular/morphological classification.

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.

Genetic basis for kidney cancer: opportunity for disease-specific approaches to therapy

BACKGROUND

Kidney cancer is not a homogenous entity; it is comprised of many different tumor types, with different biologies and molecular mechanisms leading to disease and therefore different treatment approaches.

OBJECTIVE

To describe the genetic basis and biochemical pathways underlying inherited forms of renal cancer, specifically in four described syndromes (von Hippel-Lindau [VHL], hereditary papillary renal cancer [HPRC], Birt-Hogg-Dubé [BHD] and hereditary leiomyomatosis renal cell carcinoma [HLRCC]), and to elucidate how the understanding of these diseases enables the possibility of disease-specific approaches to therapy.

METHODS

A systematic review of the published literature on inherited and sporadic forms of renal cancer was performed.

CONCLUSION

Understanding of the biology and mechanisms of different forms of kidney cancer provides an opportunity for development of new treatment options.

Thyroid follicular carcinoma-like renal tumor: a case report with morphologic, immunophenotypic, cytogenetic, and scintigraphic studies

In this report, a rare renal tumor that morphologically resembles a thyroid follicular carcinoma is described. To date, this subtype has not been integrated into a known form of renal carcinoma. A 29-year-old female patient without relevant family or social history underwent nephrectomy because of a renal tumor measuring 5 cm by the largest diameter. The macroscopically white-yellow tumor showed follicular structures with abundant eosinophilic colloidal material and focal papillary differentiation by light microscopy. Immunohistochemically, the tumor cells stained positively for cytokeratin (CK-7, CK-20, CAM 5.2) and vimentin. CD-10, CD-117, thyroid transcription factor-1, and thyreoglobulin remained completely negative. Chromosomal losses of 1, 3, 7, 9p21, 12, 17, and X were detected by fluorescence in situ hybridization. Scintigraphs showed an inconspicuous thyroid gland and no extrathyroidal pathological accumulations, making metastatic spread to the kidney highly unlikely. To our knowledge, this is the second fully documented case of a thyroid follicular carcinoma-like renal tumor. This uncommon variant is important to keep in mind to prevent unnecessary or inappropriate treatment.

Renal Cell Carcinoma in Transplant Recipients with Acquired Cystic Kidney Disease

BACKGROUND

Acquired cystic kidney disease (ACKD) is a widely known renal cell carcinoma risk factor.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

An ultrasound screening of the native kidneys in all renal transplant patients of a renal outpatient clinic who received a transplant between 1970 and 1998 and presented between 1997 and 2003 (n = 916) was initiated prospectively. A total of 561 patients were screened.

RESULTS

A total of 129 (23%) patients had ACKD; 46 (8.2%) patients had complex renal cysts (Bosniak classification, category IIF to III); and eight (1.5%) patients had newly diagnosed renal cell carcinoma, seven of which were associated with ACKD (category IV). One patient had renal cell carcinoma in the transplanted kidney. Together with 19 patients of the cohort with formerly diagnosed renal cell carcinoma (18 of them associated with ACKD), the prevalence of renal cell carcinoma among all patients was 4.8%; among the patients with ACKD, it was 19.4% (without ACKD 0.5%; P = 0.0001); and among the patients with complex renal cysts (category IIF to III), it was 54.4%. The patients with ACKD were older (54 +/- 13 versus 51 +/- 14 yr; P = 0.048), more often male (65 versus 54%; P = 0.03), more often had heart disease (44 versus 29%; P = 0.001), had larger kidneys (6.9 and 6.8 cm versus 6.0 and 5.9 cm; P < 0.001), and had more calcifications (29 versus 15%; P = 0.002). Renal cell carcinoma was bilateral in 26% of cases. Tumor histology was clear cell carcinoma in 58% and papillary carcinoma in 42% of cases; one patient had both. Only one patient had a lung metastasis, and no patient died.

CONCLUSIONS

Renal cell carcinoma occurs often after renal transplantation and that especially patients with ACKD should routinely be screened. Because ACKD after renal transplantation seems to be less frequent (23%) than during dialysis treatment (30 to 90%), renal transplantation may inhibit renal cell carcinoma.

Hereditary urological cancer syndromes

Hereditary urological cancer syndromes are rare, but it is important that they are recognized because they have important prognostic implications; prompt diagnosis can dramatically improve patient outcomes. The urologist or urological oncologist should, therefore, ascertain which tumors of the many seen in clinical practice warrant referral for the opinion of a clinical geneticist. Despite the aggressive natural history of most inherited urological cancer syndromes, organ-preserving treatments are desirable because these syndromes predispose affected patients to the formation of multifocal and metachronous tumors. Identification of the molecular mechanisms that underlie carcinogenesis in both familial and sporadic urological cancers has, in some cases, resulted in novel and specifically targeted approaches to therapy. Patients who present with early-onset or multiple tumors should be carefully investigated for the presence of a hereditary cancer syndrome, and once a diagnosis is made, appropriate screening should be instigated for family members to enable early detection of tumors both within and outside the urogenital tract.

Identification of the genes for kidney cancer: opportunity for disease-specific targeted therapeutics

Recent advances in understanding the kidney cancer gene pathways has provided the foundation for the development of targeted therapeutic approaches for patients with this disease. Kidney cancer is not a single disease; it includes a number of different types of renal cancers, each with different histologic features, a different clinical course, a different response to therapy, and different genes causing the defects. Most of what is known about the genetic basis of kidney cancer has been learned from study of the inherited forms of kidney cancer: von Hippel Lindau (VHL gene), hereditary papillary renal carcinoma (c-Met gene), Birt Hogg Dubé (BHD gene), and hereditary leiomyomatosis renal cell cancer (fumarate hydratase gene). These Mendelian single-gene syndromes provide a unique opportunity to evaluate the effectiveness of agents that target the VHL, c-Met, BHD, and fumarate hydratase pathways.

Survival Analysis of 130 Patients with Papillary Renal Cell Carcinoma: Prognostic Utility of Type 1 and Type 2 Subclassification

OBJECTIVES

To evaluate the prognostic significance of subtyping papillary renal cell carcinoma (PRCC) into type 1 and type 2 tumors.

METHODS

From 1995 to 2004, 1358 patients underwent surgery for renal cell carcinoma, of whom 130 had PRCC alone on the specimen. The tumor characteristics, including their subtype, were analyzed; small basophilic cells and large eosinophilic cells were defined type 1 and type 2 tumors, respectively. Survival analyses were performed retrospectively.

RESULTS

Of the 130 patients (110 men and 20 women, mean age 60.6 +/- 15.3 years) with PRCC, 102 underwent radical nephrectomy (78.4%) and 28 underwent partial nephrectomy (21.6%). The median tumor size was 4.5 cm (range 0.5 to 21). The comparison of the 68 (52.3%) type 1 PRCCs and 62 (47.7%) type 2 PRCCs revealed that type 2 tumors were associated with a greater stage and grade and microvascular invasion significantly (P <0.001) more often. The median follow-up was 48 months (range 2 to 111). Of the 130 patients, 22 died of cancer-specific causes, 5 (7%) with type 1 and 17 (27%) with type 2 tumors (P = 0.002). The overall and disease-free survival rate was 89% and 92% in type 1 tumors and 55% and 44% in type 2 tumors, respectively. Univariate analysis identified tumor type, stage (P <0.001), grade (P <0.001), microvascular invasion (P <0.001), an absence of foam cells (P <0.001), the presence of sarcomatoid cells (P = 0.001), and tumor necrosis (P = 0.007) as prognostic factors. Multivariate analysis retained tumor type (P = 0.034) and TNM stage (P <0.001).

CONCLUSIONS

The results of our study have shown that histologic subtyping of PRCC allows for the identification of an independent prognostic factor.

Targeting the c-Met signaling pathway in cancer

On binding to the cell surface receptor tyrosine kinase (TK) known as c-Met, hepatocyte growth factor (HGF) stimulates mitogenesis, motogenesis, and morphogenesis in a wide range of cellular targets including, epithelial and endothelial cells, hematopoietic cells, neurons, melanocytes, and hepatocytes. These pleiotropic actions are fundamentally important during development, homeostasis, and tissue regeneration. HGF signaling also contributes to oncogenesis and tumor progression in several human cancers and promotes aggressive cellular invasiveness that is strongly linked to tumor metastasis. Our present understanding of c-Met oncogenic signaling supports at least three avenues of pathway selective anticancer drug development: antagonism of ligand/receptor interaction, inhibition of TK catalytic activity, and blockade of intracellular receptor/effector interactions. Potent and selective preclinical drug candidates have been developed using all three strategies, and human clinical trials in two of the three areas are now under way.

MET expression in sporadic renal cell carcinomas

Although germline mutations of met proto-oncogene on human chromosome 7q31-34 have been known as useful molecular markers of hereditary papillary renal cell carcinoma (RCC), the expression of MET, a product of met proto-oncogene, has not been fully studied in sporadic RCC, along with its clinical significance. We investigated the expression of MET by immunohistochemistry in 182 cases of renal neoplasm encompassing 145 RCC, 25 urothelial carcinomas of renal pelvis, and 12 oncocytomas. MET was diffusely and strongly expressed in 90% of papillary RCC, all collecting duct carcinomas, and 92% of urothelial carcinomas of renal pelvis. On the contrary, clear cell RCC, chromophobe RCC, and oncocytomas were negative or focally positive for MET expression. In clear cell RCC, MET expression was positively correlated with high nuclear grade, presence of infiltrative growth, tumoral necrosis, papillary architecture, sarcomatoid component, tumoral involvement of the renal pelvis or ureter, involvement of the calyx, and lymphatic invasion. In conclusion, diffuse and strong expression of MET in papillary RCC and collecting duct carcinoma might be helpful in discriminating from the other subtypes of RCC with tubular or papillary growth. In case of MET expression observed in clear cell RCC, it might correlate with those clinicopathological parameters implying aggressive behavior.

Common pattern of unusual chromosome abnormalities in hereditary papillary renal carcinoma

In this study, we summarized cytogenetic and comparative genomic hybridization (CGH) results, mutation analysis of the MET gene, and immunohistochemistry results of tumors from three patients in the same family who were affected by hereditary papillary renal carcinoma (HPRC). All three patients showed germline mutations in the tyrosine kinase domain of the MET proto-oncogene, and developed bilateral and multiple papillary renal tumors. DNA mutation analysis showed an increased dosage of the mutant allele in six tumors from two patients but not in two tumors from the third patient. In addition to the recurrent chromosomal alterations found in papillary renal carcinomas, cytogenetic analyses revealed the presence of an identical chromosomal translocation, t(2;15)(q13;p11), in two different tumors from the same patient. Moreover, the same pattern of autosomal trisomies (+7, +12, +13, +17) was detected by CGH analysis in tumors from different siblings. Taking into account that the presence of an identical structural chromosomal aberration in two tumors and the gain of chromosome 13 are unusual chromosomal changes in this type of tumor, we can conclude that our results confirm those of other authors and suggest that the genetic predisposition to HPRC might predispose the acquisition of genomic alterations in specific chromosomes or chromosomal regions.

Identification of tumor entities of renal cell carcinoma using interphase fluorescence in situ hybridization

PURPOSE

We developed a rapid interphase fluorescence in situ hybridization (FISH) test to differentiate renal cell carcinoma (RCC) based on known genetic alterations and verified the suitability of this test for practical use.

MATERIALS AND METHODS

We composed 2 FISH test sets using 6 centromere specific and 2 region specific DNA probes of human chromosomes. Test set 1 contained centromeric probes for chromosomes 1, 2, 6 and 9, as labeled by 4 fluorescence dyes. For test set 2 we chose 3p24pter and 3p13p14 regions, and centromeric probes of chromosomes 7 and 17. Interphase nuclei of tumor specimens were prepared from 50 mum frozen tissue sections and fixed on slides. The 2 sets were hybridized simultaneously side by side on the same slide.

RESULTS

Seven clear cell carcinomas, 8 papillary carcinomas, 7 chromophobe RCCs and 3 oncocytomas were analyzed by interphase FISH. Results were compared with comparative genomic hybridization findings and pathological reports. Genetic alterations were detected in 22 of 25 analyzed tumors by FISH. FISH findings absolutely correlated with comparative genomic hybridization results. Of the analyzed carcinomas 22 could be identified correctly. In 3 tumors the histological subtypes were revised.

CONCLUSIONS

The results of this study demonstrate that the performed test set allows the accurate identification of RCC in 1 hybridization step. Therefore, FISH represents an effective method for the rapid classification of RCC.

About the origin and development of hereditary conventional renal cell carcinoma in a four-generation t(3;8)(p14.1;q24.23) family

Conventional renal cell carcinoma (CRCC) may appear in families with germline translocations involving chromosome 3, although a recurrent responsible gene has not been found. We recently described a family with CRCC and a constitutional t(3;8)(p14.1;q24.23), and we demonstrated that no genes were disrupted by the translocation breakpoints. In order to investigate the genetic origin and features of the CRCC tumors that occurred in this family, we have extended the pedigree up to four generations, and analyzed peripheral blood samples from 36 members, CRCC tumors, normal renal tissues, and a gastric tumor. (1) By means of comparative genomic hybridization (CGH), we have detected loss of the derivative chromosome carrying 3p in all CRCC but not in the corresponding normal renal tissue. In addition, by means of the fluorescence in situ hybridization technique, we have observed that not all tumoral cells lose the der(3p), which suggests that, previous to this loss, another hit should occur to initiate the transformation of normal into tumoral cells. (2) All known mechanisms of inactivation of the candidate von Hippel-Lindau (VHL) gene have been studied in the tumors, detecting alterations in 65% of them. This confirms that inactivation of the VHL gene is not always required to develop CRCC, and that (an)other suppressor gene(s) on 3p could be involved. (3) We discard FHIT as an alternative pathway to VHL. We have not found new candidate regions along 3p by using a 1-Mb resolution array-based CGH. (4) The tumorigenesis mechanism of a second gastric tumor developed in the probandus is different from that of CRCC.

Allelic loss of 3p25 associated with alterations of 5q22.3 approximately q23.2 may affect the prognosis of conventional renal cell carcinoma

Little is known about the clinical significance at the frequent association of 3p loss with 5q gain/loss in conventional renal cell carcinoma (RCC). We analyzed the clinical significance of copy number gain and loss at 5q21 approximately q23 combined with allelic loss of 3p25 (including the VHL gene). Fifty RCCs were examined by dual-color fluorescence in situ hybridization with DNA probes for D3Z1 (3cen), cCI3-865 (3p25.1 approximately p25.3), D5S23 (5p15.2), cCI5-243 (5q21.2 approximately q21.3), and cCI5-215 (5q22.3 approximately q23.2). In patients who had 3p loss, there was a significant association of loss at 5q22.3 approximately q23.2 with large tumors (>7 cm) and high-grade tumors (both P < 0.05), whereas gain at 5q22.3 approximately q23.2 was associated with low-grade tumors (P < 0.05). There was also a significant association loss at 5q21.2 approximately q21.3 high-grade tumors in patients with 3p loss (P < 0.05). Patients with 3p loss and gain at 5q22.3 approximately q23.2 had a significantly better disease-specific survival than those who had 3p loss without such gain (P < 0.05). Allelic loss of 3p25 including the VHL gene is thought to be an immediate event in the development of conventional RCC. Copy number gains or losses of 5q21 approximately q23 are thought to be events that lead to tumor progression although the clinical significance of either gains or losses is not well known.