The correlation between the loss of chromosome 14q with histologic tumor grade, pathologic stage, and outcome of patients with nonpapillary renal cell carcinoma

Roles of Loss of Chromosome 14q Allele in the Prognosis of Renal Cell Carcinoma with C-reactive Protein Abnormity

Background:

Renal cell carcinoma (RCC) is frequently associated with paraneoplastic inflammatory syndrome (PIS). This study aimed at exploring the connections between the survival rate and specific gene alterations and the potential mechanism.

Methods:

We retrospectively studied 69 surgical RCC cases from August 2014 to February 2016, including 18 cases of clear cell RCC (ccRCC) demonstrating elevated pretreatment serum C-reactive protein (CRP, Group A). Twelve of the 18 cases were symptomized with febrile episode. We also selected 49 cases of ccRCC with normal pretreatment CRP (Group B). Using 22 microsatellite markers, we compared the incidence of loss of heterozygosity (LOH) between Group A and Group B. All statistical tests are two-sided.

Results:

The 3p LOH was common in both Group A (89%) and Group B (92%). The frequency of 14q LOH in Group A (16 of 18) was higher than Group B (4 of 49, χ² = 40.97 P < 0.0001). The 3p and 14q LOH were the characteristics of ccRCC with elevated acute phase reactants, including PIS, regardless of the presence of metastasis. On the contrary, 14q LOH was a rare genomic alternation in advanced-staged ccRCC without PIS. The overall survival of patients with elevated CRP (33.3%) was lower than its counterparts (6.1%, hazard ratio=1.852, P < 0.0001) in Kaplan-Meier curve.

Conclusions:

The results imply that the disruption of a 14q gene(s) might result in not only the inflammatory manifestations in the tumor host but also the poor survival rate as well. The isolation of the gene(s) on 14q might be a vital goal in the treatment of PIS-associated RCC.

The contemporary role of renal mass biopsy in the management of small renal tumors

The selective use of percutaneous biopsy for diagnosis in renal masses is a relatively uncommon approach when compared to the management of other solid neoplasms. With recent advancements in imaging techniques and their widespread use, the incidental discovery of asymptomatic, small renal masses (SRM) is on the rise and a substantial percentage of these SRM are benign. Recent advances in diagnostics have significantly improved accuracy rates of renal mass biopsy (RMB), making it a potentially powerful tool in the management of SRM. In this review, we will discuss the current management of SRM, problems with the traditional view of RMB, improvements in the diagnostic power of RMB, cost-effectiveness of RMB, and risks associated with RMB. RMB may offer important information enabling treating clinicians to better risk-stratify patients and ultimately provide a more personalized treatment approach for SRM.

Multilocular cystic renal cell carcinoma is a subtype of clear cell renal cell carcinoma

Multilocular cystic renal cell carcinoma is an uncommon low grade renal cell carcinoma with unique morphologic features. Its cytogenetic characteristics have not been fully investigated. Its relationship to typical clear cell renal cell carcinoma is uncertain. We evaluated 19 cases of multilocular cystic renal cell carcinoma diagnosed by strict morphologic criteria using the 2004 WHO classification system. The control group consisted of 19 low grade (Fuhrman grades 1 or 2) clear cell renal cell carcinomas. Chromosome 3p deletion status was determined by dual color interphase fluorescence in situ hybridization analysis. Chromosome 3p deletion was identified in 17 out of 19 (89%) of the clear cell renal cell carcinoma cases and 14 out of 19 (74%) of the multilocular cystic renal cell carcinoma cases, respectively. There was no difference in the status of chromosome 3p deletion between clear cell renal cell carcinoma and multilocular cystic renal cell carcinoma (P=0.40). These results support the concept that multilocular cystic renal cell carcinoma as a subtype of clear cell renal cell carcinoma.

Genome-wide profiling of chromosomal alterations in renal cell carcinoma using high-density single nucleotide polymorphism arrays

The identification of genetic aberrations may help understand the mechanisms of tumorigenesis and has important implications in diagnosis, prognosis and treatment. We applied Illumina's 317K high-density single nucleotide polymorphism (SNP) arrays to profile chromosomal aberrations in clear cell renal cell carcinoma (ccRCC) from 80 patients and analyzed the association of LOH/amplification events with clinicopathological characteristics and telomere length. The most common loss of heterozygosity (LOH) were 3p (69 cases) including 38 whole 3p arm losses, 30 large fragment LOH (spanning 3p21-36), and 1 interstitial LOH (spanning 3p12-14, 3p21-22, 3p24.1-24.2 and 3p24.3), followed by chromosome losses at 8p12-pter, 6q23.3-27, 14q24.1-qter, 9q32-qter, 10q22.3-qter, 9p13.3-pter, 4q28.3-qter and 13q12.1-21.1. We also found several smallest overlapping regions of LOH that contained tumor suppressor genes. One smallest LOH in 8p12 had a size of 0.29 Mb and only contained one gene (NRG1). The most frequent chromosome gains were at 5q (32 cases), including 10 whole 5q amplification, 21 large amplifications encompassing 5q32-ter and 1 focal amplification in 5q35.3 (0.42 Mb). The other common chromosome gains were 1q25.1-qter, 7q21.13-qter, 8q24.12-qter and whole 7p arm. Significant associations of LOH at 9p, 9q, 14q and 18q were observed with higher nuclear grade. Significant associations with tumor stage were observed for LOH at 14q, 18p and 21q. Finally, we found that tumors with LOH at 2q, 6p, 6q, 9p, 9q and 17p had significantly shorter telomere length than those without LOH. This is the first study to use Illumina's SNP-CGH array that provides a close estimate of the size and frequency of chromosome LOH and amplifications of ccRCC. The identified regions and genes may become diagnostic and prognostic biomarkers as well as potential targets of therapy.

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.

Molecular and cytogenetic insights into the pathogenesis, classification, differential diagnosis, and prognosis of renal epithelial neoplasms

Renal cell carcinomas comprise a heterogeneous group of epithelial neoplasms with diverse biologic potential and variable clinical outcomes. The application of molecular and cytogenetic techniques to the study of renal neoplasms has improved our understanding of the molecular mechanisms responsible for tumor initiation and progression. Molecular classification of renal cell carcinomas has also provided new avenues for diagnosis, clinical outcome, and therapy response prediction. In this article, we review the molecular markers for various renal epithelial neoplasms and discuss the mechanisms underlying the development of these neoplasms. We also evaluate the use of molecular and cytogenetic techniques in establishing an accurate diagnosis in difficult cases and their potential usefulness in accurately classifying renal neoplasms, assessing prognosis, and selecting appropriate therapy.

Cytogenetic profile predicts prognosis of patients with clear cell renal cell carcinoma

PURPOSE

The majority of cytogenetic studies in renal cell carcinoma (RCC) have been impaired by small sample size, retrospective character, and lack of a survival end point. We prospectively studied the prognostic impact of cytogenetic abnormalities on a larger cohort of patients having up to 108 months of follow-up.

PATIENTS AND METHODS

Tumors of 282 patients who underwent nephrectomy for clear cell RCC were cytogenetically analyzed. Results were correlated with pathological factors and disease-specific survival.

RESULTS

The most frequently observed cytogenetic abnormalities were loss of 3p (60%), gain of 5q (33%), loss of 14q (28%), trisomy 7 (26%), loss of 8p (20%), loss of 6q (17%), loss of 9p (16%), loss of 4p (13%), and loss of chromosome Y in men (55%). Tumors with loss of 3p presented at lower TNM stages. Loss of 4p, 9p, and 14q were all associated with higher TNM stages, higher grade, and greater tumor size. A deletion of 3p was associated with better prognosis (P = .03), while loss of 4p (P < .001), loss of 9p (P < .01), and loss of 14q (P < .01) were each associated with worse prognosis. Loss of the Y chromosome led to improved progression-free survival in metastatic patients (P = .02). In multivariate analysis, loss of 9p was retained as an independent prognostic factor.

CONCLUSION

This cytogenetic study serves as a proof of principal that genetic information, such as loss of chromosome 9, can be obtained from widely available technology, and can provide additional prognostic information to standard clinicopathologic variables.

Application of molecular diagnostic techniques to renal epithelial neoplasms

The application of molecular and cytogenetic techniques to the study of renal neoplasia has resulted in improved understanding of the biologic mechanisms that are responsible for tumor development and progression. It also revealed that several different and specific genetic events are responsible for tumorigenesis in the various categories and subcategories of renal tumors. The ultimate goal of research on the molecular pathology of renal neoplasms is a complete understanding of the genetics of these tumors, which will, in turn, aid in making the correct diagnosis, accurately assessing prognosis, and selecting appropriate and targeted therapeutic options.

A combination of molecular cytogenetic analyses reveals complex genetic alterations in conventional renal cell carcinoma

Here we report the complex pattern of genomic imbalances and rearrangements in a panel of 19 renal cell carcinoma cell lines detected with molecular cytogenetic analysis. Consistent heterogeneity in chromosome number was found, and most cell lines showed a near-triploid chromosome complement. Several cell lines showed deletions of the TP53 (alias p53), CDKN2A (alias p16), and VHL genes. Multiplex fluorescence in situ hybridization (M-FISH) analysis revealed chromosome 3 translocated to several other partners chromosomes, as well as breakage events commonly affecting chromosomes 1, 5, 8, 10, and 17. The most common abnormality detected with comparative genomic hybridization (CGH) was deletions of chromosome 3p, with loss of the RASSF1, FHIT, and p44S10 loci frequently involved. CGH gain of 5q showed overrepresentation of the EGR1 and CSF1R genes. Recurrent alterations to chromosome 7 included rearrangement of 7q11 and gains of the EGFR, TIF1, and RFC2 genes. Several lines exhibited rearrangement of 12q11 approximately q14 and overrepresentation of CDK4 and SAS loci. M-FISH revealed several other recurrent translocations, and CGH findings included loss of 9p, 14q, and 18q and gain of 8q, 12, and 20. Further genomic microarray changes included loss of MTAP, IGH@, HTR1B, and SMAD4 (previously MADH4) and gains of MYC and TOP1. An excellent correlation was observed between the genomic array and FISH data, demonstrating that this technique is effective and accurate. The aberrations detected here may reflect important pathways in renal cancer pathogenesis.

Positive correlation between allelic loss at chromosome 14q24-31 and poor prognosis of patients with renal cell carcinoma

OBJECTIVES

To report our development of a new application of the inter-Alu long polymerase chain reaction (PCR) for genomic scanning to screen for tumor-specific alterations in tumor DNA. Using this method, we detected a rearranged chromosomal region in renal cell carcinomas (RCCs). We then examined tumor-specific allelic loss in this region using microsatellite markers and determined whether a relationship was present between this allelic loss and the clinicopathologic features of the patients.

METHODS

The inter-Alu long PCR genomic scan method was performed using RCC DNA samples and primers specific for a minor subset of the human repeat sequence Alu. We analyzed DNA samples from 42 pairs of matched normal and nonpapillary RCC tissues with seven microsatellite markers.

RESULTS

The inter-Alu long PCR genomic scan method revealed an altered DNA region on chromosome 14q24-31, which is the location of several putative tumor suppressor genes. At least one of seven microsatellite markers on chromosome 14q24-31 showed loss of heterozygosity in 23 (54.8%) of 42 informative cases of RCC. The prevalent loss region was confined to a 2-Mb region around D14S67. We found a positive correlation between the presence of the loss of heterozygosity on 14q24-31 and tumor stage (P <0.05). We also found that cases with allelic loss at 14q24-31 had a poor prognosis (P = 0.045).

CONCLUSIONS

Our inter-Alu long PCR genomic scan method is a powerful method for the screening of DNA alterations, and our data suggest that the chromosome 14q24-31 region contains likely tumor suppressor genes associated with the progression of RCC.

Impaired expression of the cell cycle regulator BTG2 is common in clear cell renal cell carcinoma

The prognosis of patients with renal cell carcinoma (RCC) is poor. A full understanding of the molecular genetics and signaling pathways involved in renal cancer development and in the metastatic process is of central importance for developing innovative and novel treatment options. In this study, BD Atlas Human Cancer 1.2 cDNA microarrays were used to identify genes involved in renal tumorigenesis. By analyzing gene expression patterns of four clear cell RCC (cRCC) cell lines and normal renal tissue, 25 genes were found differentially expressed. To determine the relevance of these genes, RNA in situ hybridization was performed on a tissue microarray generated from 61 snap-frozen primary renal cell carcinomas and 12 normal renal cortex biopsies. B-cell translocation gene 2 (BTG2), a negative cell cycle regulator, which was expressed in normal renal tissue but down-regulated in cRCC cell lines and primary cRCCs, was selected for additional experiments. Quantitative BTG2 mRNA expression analysis in 42 primary cRCCs and 18 normal renal cortex biopsies revealed up to 44-fold reduced expression in the tumor tissues. Decrease of BTG2 expression was not associated with tumor stage, grade, and survival. Cell culture experiments demonstrated that BTG2 expression was weakly inducible by the phorbolester 12-O-tetradecanoylphorbol-13-acetate in one of four cRCC cell lines. In contrast, increasing cell density led to elevated BTG2 mRNA expression in three of four cRCC cell lines. In both experiments, BTG2 mRNA levels did not reach values observed in normal renal tissue. These data suggest that down-regulation of BTG2 is an important step in renal cancer development.

Novel concepts in the staging of renal cell carcinoma

The incidence of renal cell carcinoma (RCC) continues to rise steadily; unfortunately, our ability to cure patients with metastatic RCC remains limited. When developing and evaluating new treatment protocols, it is important to consider the role of prognostic factors, often defined as pretreatment features, that are predictive of outcome. The complexity and variability of patients' individual clinical outcome and the recently recognized limitation of conventional staging systems have lead to the formulation of integrated prognostic staging systems. In this review, we discuss the evolution of various clinically relevant integrated staging systems for RCC.

Renal cancer: cytogenetic and molecular genetic aspects

To date, much progress has been made in the fields of cytogenetics and molecular genetics of renal tumors. The previous and recent findings have delineated the characteristics of the various tumors, particularly the cytogenetic and molecular differences that exist between papillary and nonpapillary clear cell renal cell carcinomas (RCCs). At the same time, new cytogenetic subtypes have emerged [e.g., t(X;1)] in subtypes of RCC, while in others (e.g., Wilms tumors) several new cytogenetic abnormalities and consequent molecular involvement have been found. In addition to Wilms tumor, papillary RCC, and clear-cell RCC, cytogenetic and fluorescence in situ hybridization analyses have been performed on several other tumors of the kidney, including chromophobic carcinoma, metanephric adenoma, collecting duct carcinoma, transitional cell carcinoma, congenital mesoblastic nephroma, and malignant rhabdoid tumors of the kidney. This review is therefore intended to present a concise update on the cytogenetic and molecular data on renal tumors, focusing mainly on the clinical usefulness of the findings reported in the literature.

Chromosome 14q LOH in localized clear cell renal cell carcinoma

The progression of a malignant tumour is understood to be the result of the accumulation of multiple genetic aberrations. As up to 14% of organ-confined renal cell carcinomas will recur after surgery, tumour clones with metastatic potential must already be present in some of these localized tumours. The association of 14q LOH with high-grade tumours and advanced tumour stage suggests an important role for the gene in tumour progression. Chromosome 14q LOH has been analysed in microdissected specimens from 130 organ-confined (UICC TNM stage 1 and 2) clear cell renal cell carcinomas using three microsatellite markers (D14S588, D14S617, GATA136B01). Tumours were classified as 14q LOH or not on the basis of LOH at one or more of the markers. The allelic imbalance ratio was used to determine both LOH and LOH proportion and the association between LOH and mortality, tumour size, histological grade and growth kinetics, measured by quantification of nucleolar organizer regions, was analysed. 14q LOH was present in 35.4% of informative cases at marker D14S588, 24.4% at D14S617, 36.4% at GATA136B01 and 39.5% for any one of the three markers. The mean 14q LOH proportion was 0.24 (range 0.009-0.80). LOH proportion correlated significantly with tumour size, AgNOR score and histological grade. It was also significantly associated with disease-specific mortality; (hazard ratio 1.22; 95% CI 1.02-1.45; p = 0.039). LOH proportion did not remain significant after adjusting for tumour size (hazard ratio 0.98; 95% CI 0.76-1.27; p = 0.90). These results indicate that the proportion of cells with 14q LOH in the tumour is associated with tumour aggressiveness; while this is not an independent predictor of survival, it may have some utility as a marker of latent metastatic potential.

Differential gene expression in renal-cell cancer

Renal-cell carcinoma (RCC) is an important cause of morbidity and mortality, and its incidence has been increasing. Malignant transformation is thought to be associated with changes in the expression of several genes, and this alteration in gene expression is believed to be critical to the development of the malignant phenotype. In this study, the expression of about 60,000 genes/expressed sequence tags in clear-cell RCC, normal kidney, and a set of diseased nonmalignant kidneys was determined with the use of the Affymetrix microarray technique, and differences in gene expression were analyzed. Many genes were found to be differentially expressed in these two sample sets. The genes that were expressed greater than four times more in RCC, those expressed only in RCC, and those expressed greater than two times more in RCC and also expressed in a limited number of other tissues were analyzed for their expression in a variety of other normal and diseased tissues. Some of the genes identified were overexpressed only in RCC among the tissues examined, and some were overexpressed in several other malignant tissues in addition to RCC. Other genes were overexpressed in RCC compared with normal kidney but were also overexpressed in diseased nonmalignant kidney or a variety of other normal tissues. All of the RCC samples could be clustered together, separate from the normal and diseased kidney samples, with the use of the Eisen clustering technique and a set of 50 genes. The observed changes in gene expression in RCC should help further the understanding of the biology of RCC and may be useful in diagnosis, treatment, and imaging.

Current status of human chromosome 14

Over the past three decades, extensive genetic, physical, transcript, and sequence maps have assisted in the mapping of over 30 genetic diseases and in the identification of over 550 genes on human chromosome 14. Additional genetic disorders were assigned to chromosome 14 by studying either constitutional or acquired chromosome aberrations of affected subjects. Studies of benign and malignant tumours by karyotype analyses and by allelotyping with a panel of polymorphic genetic markers have further suggested the presence of several tumour suppressor loci on chromosome 14. The search for disease genes on human chromosome 14 has also been achieved by exploiting the human-mouse comparative maps. Research on uniparental disomy and on the search for imprinted genes has supported evidence of epigenetic inheritance as a result of imprinting on human chromosome 14. This review focuses on the current developments on human chromosome 14 with respect to genetic maps, physical maps, transcript maps, sequence maps, genes, diseases, mouse-human comparative maps, and imprinting.

Chromosome 9 and 17 aberrations and p53 gene deletion detected by fluorescence in situ hybridization in renal-cell carcinoma

BACKGROUND AND PURPOSE

Nuclear grade and tumor stage have been reported as important prognostic factors for renal-cell carcinoma (RCC), but tumors of similar stage and grade can still exhibit wide variations in biologic behavior and clinical outcome. Fluorescence in situ hybridization (FISH) has recently been applied to RCC. This study was designed to investigate whether aberrations of some chromosomes or genes detected by FISH are related to the progression of RCC.

MATERIALS AND METHODS

We examined 52 patients with RCC, including 31 patients without metastasis (control group) and 21 patients with either concurrent or subsequent metastasis (metastatic group). Paraffin-embedded specimens of the primary tumors were analyzed by FISH for aberrations of chromosomes 9 and 17, as well as for p53 gene alterations.

RESULTS

The incidence of aberrations of chromosome 9 was higher in the metastatic group than in the control group. The p53 gene deletion rate was significantly higher in the metastatic group than in the control group. When the metastatic group was separated into concurrent and subsequent metastasis subgroups, chromosome 17 aberrations as well as p53 gene deletion were significantly more common in the subsequent metastasis group than in the control group.

CONCLUSIONS

Numerical aberrations of chromosome 17 as well as p53 gene deletion detected by FISH may be markers of chromosomal instability in RCC and are probably associated with an increased propensity to metastasize.

Molecular cytogenetic definition of three distinct chromosome arm 14q deletion intervals in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms characterized by frequent chromosome arm 14q losses. In this study, the 14q changes in a series of 39 histologically and immunohistochemically confirmed GISTs were analyzed in detail by metaphase and/or interphase fluorescence in situ hybridization (FISH) studies using 21 genetically well-characterized, region-specific 14q11-24 YAC clones. By conventional cytogenetic analysis, acquired clonal chromosome aberrations were found in 17 out of 35 tumors. Chromosome 14 was involved in 13 cases; six specimens showed complete chromosome 14 loss, while the remaining seven had structural abnormalities with the breakpoints residing within the intervals 14q11-13 or 14q22-24. Other recurrent chromosome aberrations included frequent deletions of chromosome 1p (11/17), losses of chromosome 22 (7/17), losses or deletions of chromosome arm 13 (6/17) or 15 (4/17), and gains or translocations involving chromosome 17 (4/17). Combining cytogenetic data with double-color FISH analysis, total or partial losses of 14q material were detected in 29 out of 36 tumors (81%). The 14q losses were found in all stages and histological subtypes. Two most frequent common deletion regions flanked by YACs 931B1 and 761D4, and 802E7 and 892C11 at 14q23-24 (25/30 of each; 83%) could be identified. Furthermore, 21 tumors (70%) shared a region of deletion defined by YACs 957H10 and 931E5 at 14q11-12. Our results suggest the presence of at least three distinct critical deletion regions on chromosome 14 in GISTs.

Expression profiling of renal epithelial neoplasms: a method for tumor classification and discovery of diagnostic molecular markers

The expression patterns of 7075 genes were analyzed in four conventional (clear cell) renal cell carcinomas (RCC), one chromophobe RCC, and two oncocytomas using cDNA microarrays. Expression profiles were compared among tumors using various clustering algorithms, thereby separating the tumors into two categories consistent with corresponding histopathological diagnoses. Specifically, conventional RCCs were distinguished from chromophobe RCC/oncocytomas based on large-scale gene expression patterns. Chromophobe RCC/oncocytomas displayed similar expression profiles, including genes involved with oxidative phosphorylation and genes expressed normally by distal nephron, consistent with the mitochondrion-rich morphology of these tumors and the theory that both lesions are related histogenetically to distal nephron epithelium. Conventional RCCs underexpressed mitochondrial and distal nephron genes, and were further distinguished from chromophobe RCC/oncocytomas by overexpression of vimentin and class II major histocompatibility complex-related molecules. Novel, tumor-specific expression of four genes-vimentin, class II major histocompatibility complex-associated invariant chain (CD74), parvalbumin, and galectin-3-was confirmed in an independent tumor series by immunohistochemistry. Vimentin was a sensitive, specific marker for conventional RCCs, and parvalbumin was detected primarily in chromophobe RCC/oncocytomas. In conclusion, histopathological subtypes of renal epithelial neoplasia were characterized by distinct patterns of gene expression. Expression patterns were useful for identifying novel molecular markers with potential diagnostic utility.

Fluorescent in situ hybridizaton evaluation of p53 gene deletions at a tumor interface of lingual carcinoma

OBJECTIVE/HYPOTHESIS

To evaluate the ability of fluorescent in situ hybridization (FISH) to detect malignant cells missed by standard histological assessment at an interface between malignant and normal tissue in lingual squamous cell carcinoma (SCC) and to correlate findings of FISH assessment with patients' clinical stages.

STUDY DESIGN

Retrospective assessment of archival tissue from 31 patients with lingual SCC treated at University of Wisconsin Hospital and Clinics in Madison.

METHODS

An assay combining standard histological and FISH techniques was used to assess a tumor interface tissue section and allow identification of each tumor's ploidy characteristics and p53 gene deletions and the presence or absence of malignant cells within tissue viewed as "normal" on histological review.

RESULTS

Forty-five percent of tumors (14 of 31) demonstrated ploidy changes and 84% (26 of 31) showed p53 deletions. Of these 26 tumors with p53 deletions, 14 were found to have "microfoci" with p53 deletions within tissue that appeared normal on histological examination. These microfoci were found in 75% of late-stage tumors and in only 35% of early-stage tumors.

CONCLUSIONS

FISH allowed identification of malignant cells in tissue viewed as normal on standard histological assessment, and this finding occurred more frequently in late-stage tumors.

Interphase cytogenetics of multicentric renal cell tumours confirm associations of specific aberrations with defined cytomorphologies

To demonstrate associations of certain chromosomal aberrations with defined renal cell tumour (RCT) subtypes, we analysed 239 tumour nephrectomy cases for specimens with multicentric tumours. Chromosomal in situ hybridization was then performed on 15 cases with 34 foci (16 conventional renal cell carcinomas (RCCs), and 18 papillary RCTs (11 carcinomas and seven adenomas) for specific chromosomal aberrations, using alpha-satellite probes for chromosomes 3, 7 or 17. Particular preference was given to cases which had separate foci with different cytomorphologies. Furthermore, we compared aberrations in relation to tumour size, stage, grade and between different foci in a specimen. Thirty-four cases had multiple tumours. Forty-seven per cent of the multicentric tumours were conventional RCCs and 53% papillary RCTs (against 83% solitary conventional RCCs and 5% solitary papillary RCTs). Three conventional RCCs sized 8 mm (G3), 13 cm (pT2, G2) and 15 cm (pT3b, G3), respectively, revealed monosomy 3, and 13 were disomic. Seventeen papillary RCTs (11 carcinomas and six adenomas) displayed trisomy 17, irrespective of size or grade. Four papillary carcinomas and six papillary adenomas had trisomy 7, and the rest (seven papillary carcinomas and one papillary adenoma) revealed disomy 7. In conclusion, papillary RCTs were tendentially multicentric. Although specific for conventional RCCs heedless of size, monosomy 3 was only observed in high-grade and/or advanced tumours. Trisomy 17 was only detectable in papillary RCTs irrespective of tumour state, showing increased copies with tumour growth. Papillary RCTs also appeared to lose some copies of chromosome 7 with tumour progress, possibly reflecting malignancy.

Molecular cytogenetic analysis of 17 renal cancer cell lines: increased copy number at 5q31-33 in cell lines from nonpapillary carcinomas

Comparative genomic hybridization (CGH) was used to screen for genomic imbalances in cell lines derived from 13 nonpapillary renal-cell carcinomas (RCCs), two papillary RCCs, one renal squamous-cell carcinoma, and one transitional-cell carcinoma of the renal pelvis. Aberrations were found in all 17 lines. The most frequent changes in nonpapillary RCC cell lines were gains of 5q (85%), 7q (69%), 8q (69%) and 1q (54%) and losses of 3p (92%), 8p (77%), 4q (62%) and 14q (54%). High-level gains (HLGs) were detected at 4q12, 5p, 5q23-33, 7q22-qter, 8q23-24, 10q21-qter, 12p and 12q13-22. By means of fluorescence in situ hybridization (FISH) we narrowed the smallest common region involving 5q gains to the genomic segment between D5S642 and D5S673, and found that the HLG at 4q12 possibly involved amplifications of c-kit and PDGFRA. Two papillary RCC cell lines showed gains of entire chromosomes 7, 12 and 17. The CGH data reported here should help to facilitate the choice of individual renal-tumor cell lines for exploring target genes in regions of interest.

Chromosomal abnormalities in renal cell neoplasms associated with acquired renal cystic disease. A series studied by comparative genomic hybridization and fluorescence in situ hybridization

Sporadic renal cell carcinomas (RCCs) display different chromosomal abnormalities according to their morphology; gains of chromosomes 7 and 17 and loss of Y are commonly observed in papillary lesions, whereas loss of 3p sequences and multiple losses of specific chromosomes are found in non-papillary and chromophobe cell carcinomas, respectively. Acquired renal cystic disease (ARCD) is associated with an increased incidence of renal cell tumours, especially papillary lesions. The aim of this study was to examine a series of ARCD-related tumours for chromosomal abnormalities and to compare the findings with those abnormalities commonly observed in sporadic RCCs. Nine tumours from four patients with ARCD were examined using comparative genomic hybridization (CGH) and interphase cytogenetics. Gain of chromosomes 7 and 17 was observed in all four papillary lesions and loss of Y in three. In addition, gain of chromosome 16 was observed in three papillary tumours. Three chromophobe RCCs originating from the same kidney showed different genomic profiles; two had no abnormalities, whereas one showed loss of chromosome 17p. Two non-papillary RCCs failed to show chromosome 3p alterations. In conclusion, renal cell tumours developing in ARCD may show chromosomal abnormalities both similar to and different from those seen in sporadic tumours.

Inherited carcinomas of the kidney

Studies of families with inherited carcinomas have provided powerful tools to identify the genes involved in the pathogenesis of human cancers. In this review, we summarize the clinical, pathological, and genetic characteristics of the inherited carcinomas of the kidney. We emphasize the observation that different genes predispose to histologically different types of renal carcinoma. Hereditary papillary renal carcinoma, a recently described inherited disorder, is discussed in detail along with the predisposing gene, the MET protooncogene. The data support a classification of renal carcinomas based on molecular genetics.

Comparison of chromosomal aberrations detected by fluorescence in situ hybridization with clinical parameters, DNA ploidy and Ki 67 expression in renal cell carcinoma

To evaluate the significance of chromosomal aberrations in renal cell carcinoma, fluorescence in situ hybridization (FISH) was used to determine its prevalence and correlation with clinical parameters of malignancy. In addition, correlation of chromosomal aberration with Ki 67 expression was analysed. We performed FISH with chromosome-specific DNA probes, and the signal number of pericentromeric sequences on chromosomes 3, 7, 9 and 17 was detected within interphase nuclei in touch preparations from tumour specimen. The incidence of loss of chromosome 3 was significantly higher than those of chromosomes 7, 9 and 17 (P < 0.001, P = 0.03 and P < 0.001 respectively). Hyperdiploid aberration of chromosomes 3 and 17 was significantly correlated with tumour stage (P = 0.03, P = 0.02 respectively), whereas hyperdiploid aberration of chromosome 9 was associated with nuclear grade (P = 0.04). Disomy of chromosome 7 was correlated with venous involvement (P = 0.04). Ki 67 expression was significantly associated with hyperdiploid aberration of chromosome 17 (P = 0.01), but not with aberration of chromosome 3. There was a significant relationship between hyperdiploid aberration of chromosome 7 and Ki 67 expression (P = 0.01). In conclusions, gain of chromosome 17 may reflect tumour development, and aberration of chromosome 7 may affect metastatic potential of malignancy, whereas loss of chromosome 3 may be associated with early stage of tumour development in renal cell carcinoma.

The Heidelberg classification of renal cell tumours

This paper presents the conclusions of a workshop entitled 'Impact of Molecular Genetics on the Classification of Renal Cell Tumours', which was held in Heidelberg in October 1996. The focus on 'renal cell tumours' excludes any discussion of Wilms' tumour and its variants, or of tumours metastatic to the kidneys. The proposed classification subdivides renal cell tumours into benign and malignant parenchymal neoplasms and, where possible, limits each subcategory to the most commonly documented genetic abnormalities. Benign tumours are subclassified into metanephric adenoma and adenofibroma, papillary renal cell adenoma, and renal oncocytoma. Malignant tumours are subclassified into common or conventional renal cell carcinoma; papillary renal cell carcinoma; chromophobe renal cell carcinoma; collecting duct carcinoma, with medullary carcinoma of the kidney; and renal cell carcinoma, unclassified. This classification is based on current genetic knowledge, correlates with recognizable histological findings, and is applicable to routine diagnostic practice.

Loss of heterozygosity at chromosomes 8p, 9p, and 14q is associated with stage and grade of non-papillary renal cell carcinomas

In this study, 105 non-papillary renal cell carcinomas (RCCs) have been examined for allelic loss at the chromosome 8p12-21.1, 9p21, and 14q24.2-qter regions, each by two highly polymorphic microsatellites. Loss of heterozygosity (LOH) was detected at both chromosome 8p and 9p in 33 per cent of the cases and at chromosome 14q in 45 per cent of the tumours. A correlation of variables such as size, grade, and stage of tumours with these specific genetic alterations showed that loss of chromosomes 8p and 9p, and especially loss of chromosome 14q regions, is significantly associated with a higher grade of tumour and the combined LOH at these chromosomal sites with advanced tumour stage. These genetic alterations did not show any correlation with the size of non-papillary RCCs. This study suggests that genetic markers at the above-mentioned chromosomal sites can predict the clinical outcome of non-papillary RCCs.