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Peter Schraml

Publications and source records attributed to Peter Schraml.

At least 19 recordsLinked to original sources
PubMed2006

Tissue microarrays for comparing molecular features with proliferation activity in breast cancer.

Tissue microarrays (TMAs) are potentially suited to find associations between molecular features and clinical outcome. Enhanced cell proliferation, as measured by Ki67 immunohistochemistry, is related to poor patient prognosis in many different tumor types. Ki67 expression shows considerable intratumoral heterogeneity. It is unclear if the TMA format is suitable for the analysis of potentially heterogeneous markers because of the small size of TMA spots. We have analyzed a breast cancer TMA containing 2,517 breast tissues, including 2,222 neoplastic and 295 normal or premalignant samples, for Ki67 labeling index (Ki67 LI) and additional markers with a known relationship to Ki67 LI by immunohistochemistry (ER, PR, Bcl-2, Egfr, p16, p53) and Fluorescence in situ hybridization (HER2, MDM2, CCND1, MYC). A high Ki67 LI was linked to tumor phenotype including grade (p < 0.0001), stage (p < 0.0001), nodal stage (p = 0.0018), and patient prognosis (p < 0.0001), elevated protein levels of p53, p16 and Egfr, reduced levels of Bcl2, ER, and PR (p < 0.0001 each), as well as amplifications of HER2, MYC, CCND1 and MDM2 (p < 0.0001 each). In summary, all expected associations between Ki67 and the analyzed molecular markers could be reproduced with high statistical significance using a TMA containing only one tissue sample per tumor, measuring 0.6 mm in diameter. We conclude that associations with cell proliferation can be reliably analyzed in a TMA format.

Adult↗
PubMed2006

Frequent amplifications and abundant expression of TRIO, NKD2, and IRX2 in soft tissue sarcomas.

Copy number gains and high-level amplifications of the short arm of chromosome 5 are frequently observed in soft tissue sarcomas. To identify genes from this region possibly involved in tumor progression, we analyzed 34 soft tissue sarcomas (10 pleomorphic and 8 dedifferentiated liposarcomas, 6 malignant fibrous histiocytomas, and 10 malignant peripheral nerve sheath tumors (MPNST)) using a DNA microarray including 418 BAC clones representing 99% of chromosome arm 5p. In seven tumors, distinct high-level amplifications were identified affecting four different subregions. From these regions, genes TERT, TRIO, SKP2, FBXO32, NKD2, SLC6A3, IRX2, POLS, FYB, PTGER4, and FGF10 were selected for detailed quantitative expression analysis (RQ-PCR) based on their potential tumorigenic function. Of these, TRIO, coding for a guanidine nucleotide exchange factor, was consistently overexpressed in all cases, while IRX2 and NKD2, both involved in the regulation of developmental processes via the WNT pathway, showed a characteristic expression only in MPNSTs. Detailed nonparametric multidimensional scaling analysis further showed that the expression of TRIO, IRX2, and NKD2 strongly correlated with the gene copy number. In conclusion, we found TRIO, IRX2, and NKD2 frequently affected by high-level amplifications as well as up-regulated in a gene-dosage dependent manner. Thus, these genes represent candidate targets of 5p amplifications in soft tissue sarcomas and might play a crucial role during the progression of this disease.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Predominance of high-grade pathway in breast cancer development of Middle East women.

Recent data have suggested considerable molecular differences in cancers from various ethnical groups. As molecular features are increasingly used for predicting cancer prognosis and response to therapy, better knowledge of ethnic molecular features is important. To identify potential molecular differences between breast cancers in Europe and the Middle East, we analyzed consecutive breast cancer series from Switzerland (n=2197) and Saudi Arabia (n=204). Tissue microarrays were analyzed by fluorescence in situ hybridization for HER2, CCND1, MYC, and EGFR amplification. The data revealed marked differences between Saudi and Swiss patients. Saudi breast cancers had a markedly higher frequency of HER2 (31 vs 17%; P<0.0001) and MYC (16 vs 5%; P<0.0001) amplifications than Swiss breast cancers. Remarkably, this was partly due to a much higher incidence of grade 3 cancers in the Saudi than in the Swiss population (65 vs 32%; P<0.0001). However, differences in amplification frequency hold also true within grade 3 cancers (HER2: 40 vs 30%, P<0.05; MYC: 22 vs 11%, P=0.002). Interestingly, in combination with known age standardized incidence rates of breast cancer in Saudi Arabia (21.6/100 000) and Switzerland (70.1/100 000), these data suggest that the incidence of high-grade breast cancer is comparable for Saudi and Swiss women, while the incidence of low-grade breast cancers is about 14 times lower in Saudi than for Swiss women. These observations suggest that a difference in genetic susceptibility and/or lifestyle between Saudi and Swiss women has a substantial and much higher than expected impact on the risk of low-grade breast cancer.

Adult↗
PubMed2004

Prognostic relevance of gene amplifications and coamplifications in breast cancer.

Multiple different oncogenes have been described previously to be amplified in breast cancer including HER2, EGFR, MYC, CCND1, and MDM2. Gene amplification results in oncogene overexpression but may also serve as an indicator of genomic instability. As such, presence of one or several gene amplifications may have prognostic significance. To assess the prognostic importance of amplifications and coamplifications of HER2, EGFR, MYC, CCND1, and MDM2 in breast cancer, we analyzed a breast cancer tissue microarray containing samples from 2197 cancers with follow-up information. Fluorescence in situ hybridizations revealed amplifications of CCND1 in 20.1%, HER2 in 17.3%, MDM2 in 5.7%, MYC in 5.3%, and EGFR in 0.8% of the tumors. All gene amplifications were significantly associated with high grade. HER2 (P < 0.001) and MYC amplification (P < 0.001) were also linked to shortened survival. In case of HER2, this was independent of grade, pT, and pN categories. MYC amplification was almost 3 times more frequent in medullary cancer (15.9%), than in the histologic subtype with the second highest frequency (ductal; 5.6%; P = 0.0046). HER2 and MYC amplification were associated with estrogen receptor/progesterone receptor negativity (P < 0.001) whereas CCND1 amplification was linked to estrogen receptor/progesterone receptor positivity (P < 0.001). Coamplifications were more prevalent than expected based on the individual frequencies. Coamplifications of one or several other oncogenes occurred in 29.6% of CCND1, 43% of HER2, 55.7% of MDM2, 65% of MYC, and 72.8% of EGFR-amplified cancers. HER2/MYC-coamplified cancers had a worse prognosis than tumors with only one of these amplifications. Furthermore, a gradual decrease of survival was observed with increasing number of amplifications. In conclusion, these data support a major prognostic impact of genomic instability as determined by a broad gene amplification survey in breast cancer.

Breast Neoplasms↗
PubMed2004

Different types of microsatellite instability in ovarian carcinoma.

Microsatellite instability at mono- and dinucleotide repeats is the hallmark of the hereditary non-polyposis cancer syndrome (HNPCC) and is related to deficient DNA mismatch repair. In contrast, a distinct form of microsatellite instability at selective tetranucleotide repeats (EMAST or elevated microsatellite alterations at selected tetranucleotides) was described in several non-HNPCC cancer types. EMAST is probably unrelated to mismatch repair defects. We investigated the frequency of microsatellite instability at mononucleotide, dinucleotide and tetranucleotide repeats in a series of 75 ovarian carcinomas (53 serous and 22 non-serous). Microsatellite analysis was carried out using 5 mono- and dinucleotide markers from the National Cancer Institute Consensus Panel and 6 tetranucleotide markers, which have been reported as frequently unstable in the literature. High frequency of microsatellite instability (MSI-H) at mono- and dinucleotide repeats was observed in 9% and a low frequency (MSI-L) in 21% of serous carcinomas. MSI-H was detected in 4% and MSI-L in 18% of non-serous carcinomas. Nine percent of serous carcinomas showed instability at multiple and 9% at single tetranucleotide loci. All non-serous carcinomas were stable at tetranucleotide loci. In summary, EMAST (e.g., tumors with tetranucleotide instability without concomitant MSI-H) was observed in 13% of ovarian serous carcinomas. All EMAST positive tumors were of advanced stage. We conclude that EMAST occurs as a distinct form of microsatellite instability in ovarian cancer. EMAST seems to be particularly frequent in advanced serous carcinomas. Its clinical significance needs to be investigated.

Carcinoma↗
PubMed2004

Prevalence of KIT expression in human tumors.

PURPOSE: KIT is a target for imatinib mesylate (Gleevec; Novartis Pharma, Basel, Switzerland). Gastrointestinal stromal tumors (GISTs) express KIT and respond favorably to imatinib therapy. To determine other tumors in which such a molecular targeted therapy might be indicated, we investigated KIT expression in different human tumor types. Because recent studies in GISTs suggest that KIT-activating mutations predict response to imatinib therapy, we also sequenced a subset of positive tumors. MATERIALS AND METHODS: More than 3,000 tumors from more than 120 different tumor categories were analyzed by immunohistochemistry in a tissue microarray format. Seven commercially available anti-KIT antibodies were initially evaluated. The antibody A4502 (DAKO) was selected for analysis because of a high frequency of positivity in GIST and low staining background in other tissues. To determine the frequency of KIT mutations in various tumor types, the exons 2, 8, 9, 11, 13, and 17 (where mutations previously were reported) were sequenced in 36 tumors with strong KIT expression. RESULTS: KIT positivity was detected in 28 of 28 GISTs (100%), 42 of 50 seminomas (84%), 34 of 52 adenoid-cystic carcinomas (65%), 14 of 39 malignant melanomas (35%), and eight of 47 large-cell carcinomas of the lung (17%), as well as in 47 additional tumor types. KIT mutations were found in six of 12 analyzed GISTs, but only in one of 24 other tumors. CONCLUSION: The results suggest that KIT expression occurs infrequently in most tumor types and that, with the exception of GISTs, KIT gene mutations are rare in immunohistochemically KIT-positive tumors.

Antineoplastic Agents↗
PubMed2004

Expression and amplification of therapeutic target genes in retinoblastoma.

PURPOSE: We set out to evaluate alterations of the therapeutic target genes KIT (CD 117), EGFR, and HER-2 in human retinoblastoma. METHODS: Ninety-five formalin-fixed, paraffin-embedded retinoblastomas were brought into a tissue microarray (TMA) format. Immunohistochemistry was performed to analyze the expression of CD117, EGFR, and HER-2. Fluorescence in situ hybridization (FISH) was utilized for detection of EGFR amplifications. Three tumors with strong CD117 positivity were sequenced for KIT exon 11 mutations. RESULTS: Detectable CD117 expression was seen in 19% of all interpretable cases. Sequence analysis of the three tumors with the strongest CD117 expression revealed no mutations. EGFR was positive in 14% of all cases. No EGFR amplification was observed by FISH, however. All tumors were negative for HER-2 expression. CONCLUSIONS: Our data suggest that selected cases of retinoblastoma may be candidates for anti-EGFR and imatinib mesylate (STI571) therapy.

Adolescent↗
PubMed2004

E2F3 amplification and overexpression is associated with invasive tumor growth and rapid tumor cell proliferation in urinary bladder cancer.

E2F3 is located in the 6p22 bladder amplicon and encodes a transcription factor important for cell cycle regulation and DNA replication. To further investigate the role of E2F3 in bladder cancer, a tissue microarray containing samples from 2317 bladder tumors was used for gene copy number and expression analysis by means of fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). E2F3 amplification was strongly associated with invasive tumor phenotype and high tumor grade (P < 0.0001 each). None of 272 pTaG1/G2 tumors, but 35 of 311 pT1-4 carcinomas (11.3%), had E2F3 amplification. A high E2F3 expression level was associated with high grade, advanced stage, and E2F3 gene amplification (P < 0.0001 each). To evaluate whether E2F3 expression correlates with tumor proliferation, the Ki67 labeling index (LI) was analysed for each tumor. There was a strong association between a high Ki67 LI and E2F3 expression (P < 0.0001), which was independent of grade and stage. We conclude that E2F3 is frequently amplified and overexpressed in invasively growing bladder cancer (stage pT1-4). E2F3 expression appears to provide a growth advantage to tumor cells by activating cell proliferation in a subset of bladder tumors.

Cell Division↗
PubMed2004

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.

Adenocarcinoma, Clear Cell↗
PubMed2004

TRIO amplification and abundant mRNA expression is associated with invasive tumor growth and rapid tumor cell proliferation in urinary bladder cancer.

Studies by comparative genome hybridization have suggested that 5p amplification is related to tumor progression in urinary bladder cancer. In this study seven genes (TAS2R, ADCY2, DNAH5, CTNND2, TRIO, ANKH, and MYO10) located to 5p15.31-5p15.1 were analyzed by fluorescence in situ hybridization using a tissue microarray containing samples from tumors and cell lines with known 5p amplification by comparative genome hybridization. Amplification frequency was highest for TRIO, which maps to 5p15.2 and encodes a protein with a putative role in cell-cycle regulation. To further investigate the role of TRIO amplification in bladder cancer, a tissue microarray containing samples from 2317 bladder tumors was used for fluorescence in situ hybridization analysis. TRIO amplification was strongly associated with invasive tumor phenotype, high tumor grade, and rapid tumor cell proliferation (Ki67 LI) (P < 0.0001 each). Only 7 of 456 pTaG1/G2 tumors (1.5%) but 62 of 485 pT1-4 carcinomas (12.8%) had TRIO amplification. TRIO amplification was not associated with poor prognosis. Using a frozen bladder tumor tissue microarray RNA in situ hybridization confirmed that TRIO is up-regulated in amplified tumors. It is concluded that TRIO up-regulation through amplification has a potential role in bladder cancer progression.

Carcinoma↗
PubMed2004

Morphologic and molecular characterization of renal cell carcinoma in children and young adults.

A new WHO classification of renal cell carcinoma has been introduced in 2004. This classification includes the recently described renal cell carcinomas with the ASPL-TFE3 gene fusion and carcinomas with a PRCC-TFE3 gene fusion. Collectively, these tumors have been termed Xp11.2 or TFE3 translocation carcinomas, which primarily occur in children and young adults. To further study the characteristics of renal cell carcinoma in young patients and to determine their genetic background, 41 renal cell carcinomas of patients younger than 22 years were morphologically and genetically characterized. Loss of heterozygosity analysis of the von Hippel-Lindau gene region and screening for VHL gene mutations by direct sequencing were performed in 20 tumors. TFE3 protein overexpression, which correlates with the presence of a TFE3 gene fusion, was assessed by immunohistochemistry. Applying the new WHO classification for renal cell carcinoma, there were 6 clear cell (15%), 9 papillary (22%), 2 chromophobe, and 2 collecting duct carcinomas. Eight carcinomas showed translocation carcinoma morphology (20%). One carcinoma occurred 4 years after a neuroblastoma. Thirteen tumors could not be assigned to types specified by the new WHO classification: 10 were grouped as unclassified (24%), including a unique renal cell carcinoma with prominently vacuolated cytoplasm and WT1 expression. Three carcinomas occurred in combination with nephroblastoma. Molecular analysis revealed deletions at 3p25-26 in one translocation carcinoma, one chromophobe renal cell carcinoma, and one papillary renal cell carcinoma. There were no VHL mutations. Nuclear TFE3 overexpression was detected in 6 renal cell carcinomas, all of which showed areas with voluminous cytoplasm and foci of papillary architecture, consistent with a translocation carcinoma phenotype. The large proportion of TFE3 "translocation" carcinomas and "unclassified" carcinomas in the first two decades of life demonstrates that renal cell carcinomas in young patients contain genetically and phenotypically distinct tumors with further potential for novel renal cell carcinoma subtypes. The far lower frequency of clear cell carcinomas and VHL alterations compared with adults suggests that renal cell carcinomas in young patients have a unique genetic background.

Adolescent↗
PubMed2004

HER2 analysis in breast cancer: reduced immunoreactivity in FISH non-informative cancer biopsies.

Due to the central role in predicting response to herceptin and possibly also other anticancer drugs, accurate and reproducible detection of the HER2 status is important. Fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) are the most commonly used methods for HER2 analysis. It is a disadvantage of FISH that a fraction of cases remain not interpretable probably due to suboptimal tissue handling before analysis. To investigate a possible influence of tissue damage on the results of HER2 IHC we compared the HER2 IHC results obtained in tumors with and without interpretable FISH in a breast cancer tissue microarray. The HER2 IHC results differed greatly between 1551 tumors with interpretable HER2 FISH signals and 405 breast cancers showing no FISH signals. FISH informative tumors had an IHC score of 3+ in 12.6%, 2+ in 3% and 1+ in 9.2% of cases. FISH non-informative tumors showed significantly lower IHC scores (p < 0.0001). They were IHC 3+ in 3.9%, 2+ in 3.7% and 1+ in 4.4% of cases. Overall, the data show that not only FISH but also IHC results are dependent on good tissue quality for successful analysis. Poor tissue quality can be easily identified in FISH analyses because of a lack of hybridization signals. Inappropriate tissue handling is more dangerous in IHC because an artificial lack of staining can be regarded as 'negative' result.

Adult↗
PubMed2003

Sequence analysis and high-throughput immunohistochemical profiling of KIT (CD 117) expression in uveal melanoma using tissue microarrays.

We aimed to immunohistochemically examine the expression of KIT (CD 117) in human posterior uveal melanoma and to analyze KIT-positive tumors for gene mutations. Brought into a tissue microarray (TMA) format were 101 formalin-fixed, paraffin-embedded posterior uveal melanomas. Immunohistochemistry was performed using the polyclonal anti-CD117 antibody from Dako (A4502). In ten selected KIT-positive tumors, exons 2, 8, 9, 11, 13 and 17 were sequenced. Of the 101 cases, 89 (88%) could be evaluated on the TMAs. Immunohistochemistry for CD 117 was weakly positive in 5 cases (6%), moderately positive in 10 cases (12%) and strongly positive in 57 cases (69%). No KIT mutations were detected in the analyzed exons. In conclusion, human posterior uveal melanoma frequently expresses CD117 at high levels. Although KIT mutations could not be found, it appears justified to investigate the utility of imatinib mesylate in the treatment of these patients.

Adult↗
PubMed2003

High-throughput tissue microarray analysis of G1-cyclin alterations in classical Hodgkin's lymphoma indicates overexpression of cyclin E1.

Deregulation of G1-cyclins (CCN) plays a key role in the pathogenesis of many human malignancies, including non-Hodgkin's lymphomas (NHLs). In contrast to NHL, little is known about phenotypic and genotypic changes in the regulation of the cell cycle in classical Hodgkin's lymphoma (cHL). To facilitate analysis of aberrant gene expression in cHL, a lymphoma tissue microarray (TMA) containing 752 cores of 330 different cHL samples was constructed. Direct comparison of Epstein-Barr virus (EBV) latent membrane protein 1 (LMP-1) expression in Hodgkin's and Reed-Sternberg (HRS) cells on conventional full sections with the corresponding duplicate/triplicate tumour cores on the TMA showed a concordance of 100%, indicating that cHL-TMA is a reliable and representative method for evaluating gene expression profiles in situ. Using TMA technology, protein expression and gene amplification of different G1-CCNs in cHL were analysed. Among the G1-CCNs analysed, cyclin E (CCNE) was expressed in 212/253 cases (84%). In most of the individual tumours, over 75% of the HRS cells stained positive for CCNE, suggesting that CCNE is overexpressed in cHL. This overexpression was not due to CCNE gene amplification, as judged by fluorescence in situ hybridization, and did not correlate with EBV infection, as assessed by the expression of LMP-1. Thus, the overexpression of CCNE could be caused by profound changes in HRS cell-cycle regulation that could contribute to the malignant phenotype.

Cyclin E↗
PubMed2003

Cyclin E overexpression and amplification in human tumours.

Cyclin E amplification and overexpression have recently been described in several tumour types. However, many tumour entities have never been examined for cyclin E alterations. Numerous and time-consuming experiments were previously required to determine the significance of potential oncogenes across different tumour types. To overcome this problem, tissue microarrays (TMAs) consisting of 3670 primary tumours from 128 different tumour types, 709 metastases, and 354 normal tissues were generated. Cyclin E alterations were then analysed by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). Cyclin E gene amplification was observed in 15 different tumour types and subtypes, ie rhabdomyosarcoma, urinary bladder cancer (three subtypes), ovarian cancer (two subtypes), malignant fibrous histiocytoma, adenocarcinoma of the small intestine, medullary breast cancer, gall bladder adenocarcinoma, phaeochromocytoma, gastric adenocarcinoma, squamous cell carcinoma of the uterine cervix, colonic adenocarcinoma, and endometrial carcinoma. Cyclin E protein accumulation was found in 48 different tumour types. The use of TMA technology has enabled us to expand considerably our knowledge of cyclin E alterations in human tumours. The occurrence of amplification and overexpression in many different tumour types suggests that cyclin E plays an important role in tumour biology.

Cyclin E↗
PubMed2003

Combined array comparative genomic hybridization and tissue microarray analysis suggest PAK1 at 11q13.5-q14 as a critical oncogene target in ovarian carcinoma.

Amplification of chromosomal regions leads to an increase of DNA copy numbers and expression of oncogenes in many human tumors. The identification of tumor-specific oncogene targets has potential diagnostic and therapeutic implications. To identify distinct spectra of oncogenic alterations in ovarian carcinoma, metaphase comparative genomic hybridization (mCGH), array CGH (aCGH), and ovarian tumor tissue microarrays were used in this study. Twenty-six primary ovarian carcinomas and three ovarian carcinoma cell lines were analyzed by mCGH. Frequent chromosomal overrepresentation was observed on 2q (31%), 3q (38%), 5p (38%), 8q (52%), 11q (21%), 12p (21%), 17q (21%), and 20q (52%). The role of oncogenes residing in gained chromosomal loci was determined by aCGH with 59 genetic loci commonly amplified in human tumors. DNA copy number gains were most frequently observed for PIK3CA on 3q (66%), PAK1 on 11q (59%), KRAS2 on 12p (55%), and STK15 on 20q (55%). The 11q13-q14 amplicon, represented by six oncogenes (CCND1, FGF4, FGF3, EMS1, GARP, and PAK1) revealed preferential gene copy number gains of PAK1, which is located at 11q13.5-q14. Amplification and protein expression status of both PAK1 and CCND1 were further examined by fluorescence in situ hybridization and immunohistochemistry using a tissue microarray consisting of 268 primary ovarian tumors. PAK1 copy number gains were observed in 30% of the ovarian carcinomas and PAK1 protein was expressed in 85% of the tumors. PAK1 gains were associated with high grade (P < 0.05). In contrast, CCND1 gene alterations and protein expression were less frequent (10.6% and 25%, respectively), suggesting that the critical oncogene target of amplicon 11q13-14 lies distal to CCND1. This study demonstrates that aCGH facilitates further characterization of oncogene candidates residing in amplicons defined by mCGH.

Carcinoma↗
PubMed2003

Relevance of nuclear and cytoplasmic von hippel lindau protein expression for renal carcinoma progression.

Alterations of the von Hippel-Lindau tumor-suppressor gene (VHL) on 3p25-p26 are frequent in clear-cell renal-cell carcinoma (RCC). The VHL protein (pVHL) is implicated in cell-cycle control and gene regulation, and requires transcription-dependent nuclear-cytoplasmic trafficking for its function. There are two biologically active VHL protein isoforms: pVHL(30) and pVHL(19). To study prevalence, subcellular expression and biological significance of pVHL in renal tumors, tissue microarrays with renal-cell carcinomas were immunohistochemically examined for pVHL expression. Antibodies against both protein isoforms (anti-pVHL(30)/pVHL(19)) and against pVHL(30) (anti-pVHL(30); Ig33) were used. The anti-pVHL(30)/pVHL(19) antibody showed nuclear and cytoplasmic pVHL expression, whereas the anti-pVHL(30) antibody (Ig33) detected cytoplasmic pVHL expression, suggesting that the distribution of VHL protein isoforms varies in the nuclear and cytoplasmic compartments of renal tumors. There were 175 of 398 primary clear-cell RCCs (44%) with both nuclear and cytoplasmic pVHL expression. Seventy-seven clear-cell RCCs (19%) showed only nuclear, 22 (6%) showed only cytoplasmic, and 124 tumors (31%) showed no pVHL expression. Notably, combined nuclear and cytoplasmic pVHL expression was associated with low histological grade (P < 0.0001), early tumor stage (P < 0.01), and better prognosis (P < 0.01). These results imply that alteration of subcellular pVHL trafficking is of potential relevance for the biological behavior of clear-cell RCC.

Alleles↗