Differentiation of primary and metastatic clear cell tumors in the liver by in situ hybridization for albumin messenger RNA

Clear cell neoplasms presenting as metastatic hepatic masses may be difficult to differentiate histologically and immunohistochemically from hepatocellular carcinoma (HCC) with prominent clear cell features, especially in small biopsy specimens. In situ hybridization (ISH) for albumin messenger RNA (mRNA) has been previously shown to be sensitive and specific for the detection of hepatocellular differentiation, but its use for the identification of clear cell HCC has not been previously evaluated. Among 309 cases of hepatocellular carcinoma diagnosed at Mayo Clinic between 1985 and 1998, 30 cases (9.7%) with at least 30% (range, 30%-90%; median 60%) clear cells were studied by ISH for albumin mRNA. In addition, immunohistochemical expression of AFP and polyclonal CEA, serum determination of AFP, and histopathologic analyses of the tumor were done. Forty-two clear cell tumors were used as a control group: 21 metastatic clear cell tumors to the liver (14 renal cell carcinomas and 7 adrenal cortical carcinomas) and 21 primary clear cell tumors of the retroperitoneum (10 renal cell carcinomas, 5 adrenal cortical adenomas, 4 adrenal cortical carcinomas, and 2 ovarian carcinomas). ISH for albumin mRNA was reactive in 28 of 30 cases of clear cell HCC (93%). Clear cell HCC expressed AFP (15 cases; 50%) and polyclonal CEA (19 cases; 63%). Tumors expressed either AFP or polyclonal CEA in 23 cases (77%). Elevated serum AFP was present in 24 of 26 cases (92%). These results indicate that ISH for albumin mRNA is a useful method to distinguish clear cell HCC from other clear cell carcinomas metastatic to the liver and clear cell neoplasms in the retroperitoneum.

Loss of heterozygosity in P53, BRCA1, and estrogen receptor genes and correlation to expression of p53 protein in ovarian epithelial tumors of different cell types and biological behavior

Loss of heterozygosity (LOH) of tumor suppressor genes (TSGs) in ovarian epithelial tumors of differing cell types and biological behavior has not been thoroughly investigated. Moreover, there have been conflicting reports correlating LOH of the p53 gene to overexpression of p53 protein. This study evaluated 34 formalin-fixed, paraffin-embedded ovarian epithelial tumors for LOH by polymerase chain reaction (PCR) for the following microsatellite markers: TP53(17p13.1/p53 gene), D17S579(17q/BRCA1 gene), and ESR (6q24-27/estrogen receptor gene). LOH of the TP53 marker was detected in 4 (44%) of 9 informative serous cystadenocarcinomas (SCa) but in 0 of 4 informative clear cell carcinomas (CCa) and 0 of 5 informative serous tumors of low malignant potential (SLMP). LOH of the BRCA1 marker was detected in 5 (83%) of 6 informative SCa, but in 1 (13%) of 8 informative CCa and 1 (14%) of 7 informative SLMP. LOH of the ESR marker was detected in 4 (50%) of 8 informative SCa, but in 0 of 4 informative CCa and 1 (16%) of 6 informative SLMP. p53 protein overexpression was present in 8 of 12 SCa but did not correlate to TP53 LOH. LOH for TP53, D17S579/ BRCA1, and ESR is common in ovarian SCa, and is observed in primary tumors as well as metastases. In contrast, these genetic alterations are less common in CCa and in the biologically less aggressive SLMP tumors. These data suggest different mechanisms of oncogenesis in ovarian epithelial tumors of different cell types and biological behavior.

A case-control study of galactose consumption and metabolism in relation to ovarian cancer

Consumption or metabolism of dairy sugar and ovarian cancer have been linked based on evidence that galactose may be toxic to ovarian germ cells and that ovarian cancer is induced in animals by depletion of oocytes. We assessed consumption of dairy products and obtained blood for biochemical and molecular genetic assessment of galactose metabolism in 563 women with newly diagnosed epithelial ovarian cancer and 523 control women selected either by random digit dialing or through lists of residents in eastern Massachusetts and New Hampshire. We observed no significant differences between cases and controls in usual consumption of various types of dairy products or total daily lactose (the principal source of galactose in the diet); nor did we find that RBC activity of either galactose-1-phosphate uridyl transferase (GALT) or galactokinase differed. The mean (and SE) activity of uridine diphospho-galactose 4'-epimerase (in micromoles per hour per gram of hemoglobin) was, however, significantly lower (P < 0.005) in cases compared with controls, 20.32 (0.31) versus 21.64 (0.36). Ovarian cancer cases were also more likely to carry the N314D polymorphism of the GALT gene, generally predisposing to lower GALT activity. The difference was most evident for endometrioid and clear cell types of ovarian cancer, in which 3.9% of cases were found to be homozygous for N314D compared with 0.4% of controls, yielding an odds ratio and 95% confidence interval of 14.17 (2.62-76.60). We conclude that, whereas adult consumption of lactose carries no clear risk for the disease, certain genetic or biochemical features of galactose metabolism may influence disease risk for particular types of ovarian cancer.

Four new human renal cell carcinoma cell lines expressing globo-series gangliosides

Clinicopathological studies revealed that monosialosyl galactosyl globoside (MSGG) and disialosyl galactosyl globoside (DSGG) expressed by renal cell carcinoma (RCC) are one of the biochemical indicator related to the metastatic potential. The present study examines the characteristics of four new human RCC cell lines and compares the expression of MSGG and DSGG among them using TLC immunostaining and flow cytometry. TOS-1 and TOS-2 were derived from metastatic subcutaneous tissues. TOS-3 and TOS-3LN were derived from the primary lesion and from metastatic lymph nodes respectively. Monolayer culture, light microscopy and electron microscopy of these cells showed that these cell lines were derived from RCC. TLC immunostaining and flow cytometric analysis revealed increased levels of MSGG in TOS-2 and TOS-3LN, and increased DSGG in TOS-1 and TOS-3LN. These cell lines would be useful for functional studies of globo-series ganglioside expressed by RCC.

Establishment and characterization of human ovarian clear cell adenocarcinoma cell line (SMOV-2), and its cytotoxity by anticancer agents

A novel cell line derived from a surgically resected ovarian clear cell adenocarcinoma of 46 year-old Japanese woman was established and designated SMOV-2. Cells of this lineage were continuously propagated in vitro over 44 months and were grown in a mono-layered sheet with a doubling time of 48.2 hours. The histopathology of the transplanted tumor in nude mice showed two distinctive cell types, hobnail cells and clear cells, which demonstrated recognizable characteristics of clear cell adenocarcinoma, as compared to resected original tumors. At the molecular level, SMOV-2 cells had the wild type p53 genes that were free from missence mutations. Anticancer agents (cisplatin and paclitaxel) were examined for cytotoxity against these SMOV-2 cells in vitro. These examinations revealed that the chemotherapy-treated cells had decreased proliferation, cell cycle arrests, and induction of apoptosis by the anticancer agents. As can be gleaned from this research, SMOV-2 is a valuable model to study the mechanism of apoptotic responses of solid tumors to future anticancer agents.

Overexpression of H-Ryk in mouse fibroblasts confers transforming ability in vitro and in vivo: correlation with up-regulation in epithelial ovarian cancer

Abnormalities in the function of receptor tyrosine kinases (RTKs) have been demonstrated to be important in the pathogenesis of cancer. H-Ryk, a new member of the RTK family, is an unusual RTK in that it is catalytically inactive because of amino acid substitutions of conserved residues in the catalytic domain. We show by immunohistochemistry that it is expressed in the epithelium, stroma, and blood vessels of normal tissues. Evaluation of a panel of 33 primary ovarian tumors (2 benign, 8 borderline, and 23 malignant) was performed. H-Ryk was overexpressed in borderline and malignant ovarian tumors. In serous and clear cell subtypes, there was increased expression in the epithelium, stroma, and blood vessels. Consistent with this observation, overexpression of H-Ryk in the mouse fibroblast cell line NIH3T3 induces anchorage-independent growth and tumorigenicity in nude mice. This implies that overexpression of the receptor can be transforming and may therefore be significant in the pathogenesis of ovarian cancer.

Renal tumors exhibiting granular cytoplasm

Renal epithelial neoplasms consist of a group of distinct genetic and clinical entities that occasionally have overlapping morphological features. Pronounced cytoplasmic granularity or eosinophilia may be seen in a number of tumor types, including conventional (clear-cell) carcinomas, papillary carcinomas, chromphobe carcinoma, collecting duct carcinomas, and oncocytomas. Mesenchymal neoplasms such as angiomyolipomas as well as metastatic lesions such as malignant melanoma may have marked epithelial features and cytoplasmic granularity, thus mimicking a renal epithelial tumor. The same can be said for adrenal cortical neoplasms, which sometimes may be confused clinically, radiographically, and pathologically with a renal neoplasm. Close attention to morphological and cytologic detail will solve the differential diagnosis in the majority of cases, although some will require ancillary studies such as histochemistry, immunohistochemistry, and election microscopy. In a small percentage of cases molecular genetic studies are required to properly classify the tumor.

Transforming growth factor beta1 is a target for the von Hippel-Lindau tumor suppressor and a critical growth factor for clear cell renal carcinoma

The von Hippel-Lindau (VHL) tumor suppressor gene is mutated in patients with VHL disease and in the majority of patients with sporadic clear cell renal carcinoma (RCC). Overexpression of transforming growth factor (TGF) beta1 has been observed in patients with several cancers, including RCCs, with serum and urine levels correlating inversely with prognosis. We have demonstrated that the VHL tumor suppressor gene product represses TGF-beta1 mRNA and protein levels (approximately 3-4-fold) in 786-O RCC cells by decreasing the TGF-beta1 mRNA half-life. Exogenously added TGF-beta1 did not suppress the growth of 786-O cells in vitro, nor did the addition of neutralizing antibody (Ab) against TGF-beta have any effect. Indeed, 786-O cells were found to express no TGF-beta type II receptor protein, thus allowing them to escape from the negative growth control of TGF-beta1. In contrast to the in vitro data, neutralizing Ab to TGF-beta inhibited tumorigenesis and, in some cases, regressed established 786-O tumors in athymic mice. Immunohistochemistry for von Willebrand's factor revealed a 3-4-fold lower tumor microvessel count in the mice treated with TGF-beta Ab compared to controls, suggesting that the Ab was inhibiting angiogenesis. Our findings indicate that TGF-beta1 is a novel target for the VHL tumor suppressor and that antagonizing its paracrine action may provide novel avenues for treatment of RCCs as well as other tumors that secrete TGF-beta1.

Advances in the molecular basis of renal neoplasia

The past 2 years have provided exciting progress in elucidating the molecular basis of renal cancer. Work on the von Hippel-Lindau tumor suppressor, pVHL, in clear-cell renal cancer is already suggesting new potential therapies, and should have important implications in the pathogenesis of renal cystic disease and tumor angiogenesis. In addition, study of the Wilms' tumor suppressor, WT1, is revealing much about the pathogenesis of Wilms' tumor, urogenital development, and glomerular podocyte biology. c-met, the gene encoding the hepatocyte growth factor receptor, has recently been identified as a causative gene for hereditary papillary renal cancer. This review will highlight these and other new molecular advances in the renal cancer field.

Loss of HNF1alpha function in human renal cell carcinoma: frequent mutations in the VHL gene but not the HNF1alpha gene

Human renal cell carcinoma (RCC) is a common malignant disease of the kidney characterized by dedifferentiation of renal epithelial cells. Our previous experiments showed that most RCCs have a loss of function of the tissue-specific transcription factor hepatocyte nuclear factor (HNF) 1alpha. Detailed analyses of the 10 exons encoding HNF1alpha in 32 human RCCs by single-strand conformation polymorphism analysis and direct DNA sequencing revealed no tumor-associated mutation, whereas with the same probes we frequently found mutations in the von Hippel-Lindau tumor suppressor gene. No mutation leading to loss of HNF1alpha function was detected by analyzing the integrity of the HNF1alpha transcripts in the RNA derived from RCCs by the protein truncation test. Investigating human RCC cell lines by western blotting and gel retardation assays showed a dramatic loss in the expression of the tissue-specific transcription factor HNF1alpha in eight of 10 cell lines. As the HNF1alpha-related transcription factor HNF1beta was expressed in all these tumor cell lines, the loss of HNF1alpha expression was a specific event and was maintained in RCC cell lines. The loss of HNF1alpha expression in RCC cell lines on the RNA level was confirmed by reverse transcription polymerase chain reaction. We propose that tumor-associated mutations in the HNF1alpha gene do not occur in human RCC and that the loss of function is partially due to a transcriptional inactivation of the HNF1alpha gene.

HER-2/neu amplification and overexpression in endometrial carcinoma

HER-2/neu is a proto-oncogene associated with poor prognosis in women with breast and ovarian carcinoma. The significance of HER-2/neu in endometrial carcinoma is less clearly established. The authors compared HER-2/neu gene amplification using fluorescence in situ hybridization and protein overexpression using immunohistochemistry with survival in patients with endometrial carcinoma. Fluorescence in situ hybridization and immunohistochemical staining were performed on 72 formalin-fixed, paraffin-embedded endometrial carcinoma specimens. Vysis combination HER-2/neu and centromere 17 probe mixture was applied to isolated tumor cell nuclei. A minimum of 200 nuclei were scored for each specimen using standard signal enumeration criteria. A specimen was considered amplified with 5% or greater amplified nuclei. Tissue sections were immunostained with polyclonal antibody against p185erb-2 transmembrane glycoprotein. Immunohistochemical reactivity was scored on a three-tiered scale. HER-2/neu gene amplification and protein overexpression were detected in 15 of 72 (21%) and 12 of 72 (17%) of the specimens, respectively, with 2 cases of normal copy overexpression and 5 cases of amplification without overexpression. Both amplification and overexpression were associated with higher grade tumors. Amplification was associated with clear cell and serous subtypes (p = 0.002), and overexpression with only clear cell type (p = 0.006). Using the proportional hazards model of survival, amplification was found to have significant negative predictive value beyond stage, grade, and cell type (p = 0.002). HER-2/neu gene amplification as detected by fluorescence in situ hybridization in archival material has significant prognostic value.

Molecular expression of PSMA mRNA and protein in primary renal tumors

Human prostate-specific membrane antigen (PSMA), a 100-kDa integral transmembrane glycoprotein, is considered to be a highly specific marker of the prostate gland, and has successfully been used as a marker of circulating prostatic epithelial cells. Extended PSMA homology has been demonstrated with a cDNA found in rat cerebral and renal tissues. In this study, we aimed to evaluate the expression of PSMA mRNA in a variety of human renal cancer tissues (n = 20) and cell lines (n = 12). Using reverse transcriptase-polymerase chain reaction, DNA sequencing, blottings, and specific anti-PSMA labelling with CYT 351 antibody, we identified PSMA mRNA and protein in normal and in neoplastic renal tissue. The sequence of the polymerase-chain-reaction products is identical to that of PSMA cDNA derived from prostate tissue. Immunological staining with the CYT 351 reveals that PSMA is expressed mainly in tubular cells. Since PSMA does not appear to be restricted to prostatic tissue, this novel biomarker may prove useful in the staging of renal cancer and in the search for the hematogenous spread of renal cells.

Loss of heterozygosity at 3p14.2 in clear cell renal cell carcinoma is an early event and is highly localized to the FHIT gene locus

The VHL tumor suppressor gene (TSG) at 3p25-26 is strongly implicated in the pathogenesis of clear cell renal cell carcinoma (cRCC). In addition, 3p14.2 and 3p21 are suspected of harboring additional TSGs in cRCC, with FHIT being a candidate TSG at 3p14.2. We examined 87 microdissected, histologically well-defined cRCCs classified according to tumor-node-metastasis (TNM) stage (stage 1, 23 cases; stage 2, 14 cases; stage 3, 24 cases; stage 4, 26 cases) and Fuhrman grade (grade 1, 24 cases; grade 2, 19 cases; grade 3, 19 cases; grade 4, 8 cases; sarcomatoid cRCC, 17 cases) for loss of heterozygosity (LOH) at 3p14.2 and 3p25-26 using a series of precisely mapped microsatellite probes. We found that LOH at 3p14.2 exceeded LOH at 3p25-26 in frequency (69% versus 48.3%; P < 0.03) and was highly localized to markers within the FHIT gene locus (D3S1300 and D3S4260), with the majority of chromosomal breakpoints also mapping to this region. In addition, 3p14.2 LOH (P < 0.03), but not 3p25-26 LOH (P = nonsignificant), was associated with lower tumor grades (grades 1-3). These findings suggest that 3p14.2 genomic deletions may be among the earliest events in cRCC pathogenesis, preceding genomic deletions at the VHL locus. FHIT, or an as yet undiscovered TSG mapping to the D3S4103-D3S4260 interval, could be the molecular target of the 3p14.2 deletions.

Expression of human telomerase subunits in ovarian malignant, borderline and benign tumors

Telomerase activity is involved in the maintenance of telomere length and is thought to be required for cellular immortality and oncogenesis. Three major subunits composing telomerase, human telomerase RNA (hTR), telomerase-associated protein (TPI) and human telomerase catalytic subunit (hTERT), have been identified. However, their functions and the regulatory mechanisms by which telomerase is activated have not been fully determined. In the present study, a total of 35 epithelial ovarian cancers, 5 ovarian low potential malignancies (LPM), 11 ovarian benign cysts and 12 normal ovaries, as well as various cell lines derived from ovarian cancers, were examined for the expression of hTR, TPI mRNA and hTERT mRNA. Correlations of expression with telomerase activity were evaluated. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed that hTR and TPI mRNA were expressed in more than 80% of ovarian cancers, LPM, ovarian cysts and even in normal ovaries. However, hTERT mRNA was observed only in ovarian cancers, most of which exhibited telomerase activity. Normal ovarian tissues, ovarian cysts and LPM, most of which had no telomerase activity, did not express hTERT. Five telomerase-positive ovarian cancer cell lines expressed each of the telomerase subunits, whereas 2 telomerase-negative normal primary fibroblast cell lines expressed TPI mRNA and hTR, but not hTERT mRNA. There was a significant correlation of telomerase activity with hTERT mRNA expression but not with TPI or hTR expression. Expression of hTERT is thus specific to cancer lesions and appears to be a rate-limiting determinant of the enzymatic activity of human telomerase. Up-regulation of hTERT may play a critically important role in the development of ovarian cancers.

Loss of chromosomes in clear cell renal cell carcinoma and in corresponding renal parenchyma

Chromosome studies were done on six renal cell carcinomas (RCC) and on the corresponding renal parenchymas of the tumor bearing kidneys. Histopathologically, all tumors belonged to the clear cell subtype. All examined parenchymas were pathologically benign. None of the tumor cells showed the typical chromosomal aberrations described for (nonpapillary) RCC, i.e. deletions in the short arm of chromosome #3, or gains in the long arm of chromosome #5. In our series both the tumor and the benign kidney tissues were characterized by loss of chromosomes, especially of the chromosomes #6, #9, #16, #20, and of the Y chromosome. Trisomy of chromosome #7 was found frequently in benign parenchyma cells. The identical chromosomal changes in the tumor and in the parenchyma tissues might reflect rather in vivo mosaics rather than primary chromosomal aberrations in the oncogenetic process of clear cell RCC.

Interphase fluorescence in situ hybridization studies of ovarian adenocarcinomas using the midisatellite probe

The genes involved in ovarian carcinogenesis are largely unknown. Cytogenetic studies have shown a large number of chromosomal abnormalities in ovarian cancers. Molecular studies have additionally found abnormalities. Few in situ hybridization studies have been performed on ovarian cancer tissues. We chose to study the distal region of chromosome 1p with the midisatellite probe and interphase fluorescence in situ hybridization. A total of 35 patient samples, including various controls and cancers, was collected from our pathology archives. Our cancer cases included some patients with stage I disease, in whom tumors arose in endometriotic cysts. In these cases, both tumor tissue and areas in the cyst distant from the tumor mass were examined. Results showed clear cell carcinoma nuclei to have an increase in both number and size of probe signals, interpreted as representing amplification of the probed region of chromosome 1. Serous carcinomas showed an increase in the number of signals, up to four. We felt this could be a result of amplification, or, because these cells exhibited the highest mitotic counts, to DNA doubling in preparation for mitosis. Endometrioid carcinomas resembled controls in showing up to two small probe signals, but not more. We conclude that amplification in distal chromosome 1p occurs in ovarian clear cell, and possibly serous, carcinomas and may not be important in endometrioid carcinomas. Because alteration was not found in the various control epithelia, including nonmalignant-looking areas from cysts which also contained cancer, we believe that the change, when present, may not be an early step in carcinogenesis.

Increased expression of the RIalpha subunit of the cAMP-dependent protein kinase A is associated with advanced stage ovarian cancer

The primary element in the cAMP signal transduction pathway is the cAMP-dependent protein kinase (PKA). Expression of the RIalpha subunit of type I PKA is elevated in a variety of human tumours and cancer cell lines. The purpose of this study was to assess the prognostic importance of RIalpha expression in patients with ovarian cancer. We have evaluated the expression of RIalpha in a panel of human ovarian tumours (n = 40) and five human ovarian cancer cell lines using quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The human ovarian cell lines OAW42 and OTN14 express high endogenous levels of RIalpha mRNA and protein (at significantly higher mRNA levels than high tissue expressors, P < 0.05). The ovarian cell line A2780 expresses low endogenous levels of RIalpha mRNA and protein (also at higher mRNA levels than low tissue expressors, P < 0.05). Quantitative RT-PCR revealed no significant difference in RIalpha mRNA expression between different ovarian histological subtypes in this study. No associations were found between RIalpha mRNA expression and differentiation state. RIalpha mRNA expression was significantly associated with tumour stage (P = 0.0036), and this remained significant in univariate analysis (P = 0.0002). A trend emerged between RIalpha mRNA expression levels and overall survival in univariate analysis (P = 0.051), however, by multivariate analysis, stage remained the major determinant of overall survival (P = 0.0001). This study indicates that in ovarian epithelial tumours high RIalpha mRNA expression is associated with advanced stage disease. RIalpha expression may be of predictive value in ovarian cancer and may be associated with dysfunctional signalling pathways in this cancer type.

von Hippel-Lindau gene mutations in N-nitrosodimethylamine-induced rat renal epithelial tumors

BACKGROUND

Mutations in the von Hippel-Lindau (VHL) gene are common in human clear cell kidney cancers. Carcinogens in cigarette smoke, especially nitrosamines, are known to induce kidney tumors of a variety of histologic types in rodents--but with no evidence of VHL mutations; however, none of these tumors resembled human clear cell carcinomas. We examined N-nitrosodimethylamine-induced kidney tumors of the clear or mixed clear/granular cell type in Wistar rats to assess the presence of VHL mutations.

METHODS

Sections of eight clear or mixed clear/granular cell kidney tumors that had been formalin fixed and paraffin embedded were microdissected. DNA was extracted from the microdissected tissue, and exons 1-3 of the rat VHL gene were examined by use of polymerase chain reaction and cycle sequencing techniques.

RESULTS

Four VHL gene mutations (three G:C to A:T and one A:T to G:C) were detected in three of the tumors in contrast to no mutations in 40 previously reported rat kidney tumors of other histologic types (three of eight tumors versus none of 40; two-sided Fisher's exact test; P=.003). Only tumors showing prominent swollen clear cell cytology with a signet-ring appearance had VHL mutations.

CONCLUSIONS

To our knowledge, this is the first report of VHL mutations in kidney tumors after direct chemical exposure and provides a possible molecular pathway linking tobacco smoking to kidney cancer.

Microsatellite analysis of plasma DNA from patients with clear cell renal carcinoma

Deletions of DNA sequences on chromosome 3p [loss of heterozygosity (LOH)] are characteristic of clear cell renal carcinoma, which accounts for about 80% of all renal malignancies. Comparing tumor DNA to DNA from normal cells, LOH analysis of microsatellite sequences has aided in molecular diagnosis of renal carcinoma. Because clinically useful tumor markers do not exist for this cancer entity, the aim of the present study was to detect chromosome 3p microsatellite alterations (LOH and microsatellite instability) in plasma DNA from patients with clear cell renal carcinoma. Four chromosome 3p microsatellites (D3S1307, D3S1560, D3S1289, and D3S1300) were amplified by fluorescent PCR using DNA isolated from normal blood cells and plasma of 40 patients. Corresponding tumor DNA was available from 21 patients. Analyzing PCR products on an automated DNA sequencer, we found LOH in at least one locus in 25 plasma samples (63%), and 14 plasma samples (35%) exhibited LOH at more than one locus. Microsatellite instability of plasma DNA was detectable in one patient (3%). No significant association of advanced (>T2N0M0) tumor stages with LOH in plasma DNA could be demonstrated. If present, modifications of plasma DNA and tumor DNA were identical. No alterations of plasma DNA were found in healthy controls. Analysis of plasma DNA from patients with clear cell renal carcinoma reveals tumor-specific microsatellite alterations and may therefore have diagnostic potential as a molecular tumor marker.

Clear-cell and papillary carcinoma of the kidney: an analysis of chromosome 3, 7, and 17 abnormalities by microsatellite amplification, cytogenetics, and fluorescence in situ hybridization

Clear-cell and papillary renal cell carcinomas (RCCs) have specific genetic changes that allow them to be classified on the basis of histopathology and on the basis of cytogenetic and molecular genetic findings. Clear-cell carcinomas are characterized by a deletion of gene sequences on the short arm of chromosome 3 (3p). Papillary RCCs do not have 3p deletions but have an increase in chromosomal number that usually includes trisomies of chromosomes 7 and 17. This study was undertaken to determine whether PCR-amplified DNA microsatellites can be used to detect numerical abnormalities of chromosomes 7 and 17 and whether the numerical abnormalities and 3p deletions that are detected by microsatellite analysis can be correlated with histopathologic tumor types. A series of histologically unambiguous RCCs consisting of three papillary and ten clear-cell RCCs were studied by cytogenetics and by fluorescence in situ hybridization (FISH) with chromosome 7 and 17 centromeric probes. Microsatellites on the long and short arms of chromosomes 3, 7, and 17 were amplified in paired normal tissue and tumor samples, and the reaction products were analyzed for differences between the normal and the tumor allele ratios. Clear-cell carcinomas showed loss of heterozygosity (LOH) of 3p but not 3q alleles in eight of ten cases. LOH of 3p and 3q was seen in one case of papillary RCC that cytogenetically had two normal chromosomes 3. This indicated a nondisjunction duplication that could be confused with monosomy 3 if only microsatellite studies were performed. Differences in microsatellite allele ratios between normal tissue and tumor correlated with the presence of trisomy 7 that was identified in clear-cell and papillary RCCs by cytogenetics and by FISH. Microsatellite analysis did not detect numerical chromosome 17 abnormalities in the papillary RCCs but did show an abnormality in one clear-cell carcinoma that was markedly aneusomic for chromosomes 7 and 17 by FISH. In this collection of cases, microsatellite amplification genetically distinguished only clear-cell RCCs showing 3p but not 3q LOH as a separate class of tumors. The method detected abnormalities in chromosome number that were found in both clear-cell and papillary RCCs.

Clear cell sarcoma of tendons and aponeuroses (malignant melanoma of soft parts) and cutaneous melanoma: exploring the histogenetic relationship between these two clinicopathological entities

Clear cell sarcoma of tendons and aponeuroses (CCS) has come to be recognized as a distinct histopathological entity in the last three to four decades. It shares a number of histological and ultrastructural features with cutaneous melanoma (MM), occasionally creating diagnostic difficulties with metastatic melanoma in the absence of a known primary cutaneous tumour. At a genetic level, a t(12;22) has been identified in 60-75 per cent of cases of CCS using karyotype analysis, while MM demonstrates a broad range of genetic alterations, most commonly appearing to involve chromosomes 1, 5, and 6. Although these two tumour types share many common microscopic, and thus histogenetic, similarities, the genotypic evidence supports two distinct histopathological entities.

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.