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H Brauch

Publications and source records attributed to H Brauch.

At least 19 recordsLinked to original sources
PubMed2000

Up-regulation of hypoxia-inducible factors HIF-1alpha and HIF-2alpha under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function.

Hypoxia induces transcription of a range of physiologically important genes including erythropoietin and vascular endothelial growth factor. The transcriptional activation is mediated by the hypoxia-inducible factor-1 (HIF-1), a heterodimeric member of the basic helix-loop-helix PAS family, composed of alpha and beta subunits. HIF-1alpha shares 48 per cent identity with the recently identified HIF-2alpha protein that is also stimulated by hypoxia. In a previous study of hemangioblastomas, the most frequent manifestation of hereditary von Hippel-Lindau disease (VHL), we found elevated levels of vascular endothelial growth factor and HIF-2alpha mRNA in stromal cells of the tumors. Mutations of the VHL tumor suppressor gene are associated with a variety of tumors such as renal clear cell carcinomas (RCC). In this study, we analysed the expression of the hypoxia-inducible factors HIF-1alpha and HIF-2alpha in a range of VHL wildtype and VHL deficient RCC cell lines. In the presence of functional VHL protein, HIF-1alpha mRNA levels are elevated, whereas HIF-2alpha mRNA expression is increased only in cells lacking a functional VHL gene product. On the protein levels, however, in VHL deficient cell lines, both HIF-alpha subunits are constitutively expressed, whereas re-introduction of a functional VHL gene restores the instability of HIF-1alpha and HIF-2alpha proteins under normoxic conditions. Moreover, immunohistochemical analyses of RCCs and hemangioblastomas demonstrate up-regulation of HIF-1alpha and HIF-2alpha in the tumor cells. The data presented here provide evidence for a role of the VHL protein in regulation of angiogenesis and erythropoiesis mediated by the HIF-1alpha and HIF-2alpha proteins.

Basic Helix-Loop-Helix Proteins↗
PubMed2000

VHL alterations in human clear cell renal cell carcinoma: association with advanced tumor stage and a novel hot spot mutation.

To elucidate the role of somatic alterations for renal cancer etiology and prognosis, we analyzed 227 sporadic renal epithelial tumors for mutations and hypermethylations in the von Hippel-Lindau tumor suppressor gene VHL. Tumors were classified according to the recommendations of the Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC). Somatic VHL mutations were identified by PCR, single-strand conformation polymorphism analysis, and sequencing, and hypermethylations were identified by restriction enzyme digestion and Southern blotting. Frequencies of VHL alterations were established, and an association with tumor type or tumor type and tumor stage was evaluated. VHL mutations and hypermethylations were identified in 45% of clear cell renal cell carcinomas (CCRCCs) and occasionally (3 of 28) in papillary (chromophilic) renal cell carcinomas (RCCs). Lack of VHL mutations and hypermethylations in chromophobe RCCs and oncocytomas was statistically significant (P = 0.0001 and P = 0.0004, respectively). RCCs carrying VHL alterations showed, in nine cases (12%), mutations at a hot spot involving a thymine repeat (ATT.TTT) in exon 2. Tumor staging was critical to the VHL mutation/hypermethylation detection rate in CCRCCs shown by separate evaluation of patients from medical centers in Munich, Heidelberg, and Mainz. The spectrum of pT1, pT2, and pT3 CCRCCs and the VHL mutation/hypermethylation detection rate varied among these three groups. Altogether, VHL alterations were significantly associated with pT3 CCRCCs (P = 0.009). This is the first evidence of frequent somatic VHL mutations at a particular site within exon 2 and an association of VHL mutations/hypermethylations with a standard prognostic factor.

Adenoma, Oxyphilic↗
PubMed1999

Trichloroethylene exposure and specific somatic mutations in patients with renal cell carcinoma.

BACKGROUND: The development of renal cell carcinoma (RCC) has been associated with both genetic and environmental factors-with mutations in the von Hippel-Lindau (VHL) tumor suppressor gene for clear-cell RCC specifically and with long-term exposure to high doses of trichloroethylene (TRI), an industrially important solvent, for RCC generally. We investigated whether TRI exposure produces RCC through a specific mutational effect on the VHL gene by analyzing VHL sequences in the RCCs of patients exposed to high, cumulative doses of TRI. METHODS: The level of exposure for each of 44 patients with RCC who had known industrial exposure to TRI was classified according to the duration, frequency, and mode of exposure. Samples of normal and cancerous tissues were microdissected from paraffin-embedded tissue. DNA was isolated from these samples, and somatic VHL mutations were identified by polymerase chain reaction analysis, single-strand conformation polymorphism analysis, DNA sequencing, and restriction enzyme digestion. Control samples included RCC DNA from 107 patients without known TRI exposure and lymphocyte DNA from 97 healthy subjects. RESULTS: RCCs of TRI-exposed patients showed somatic VHL mutations in 33 (75%) of 44 cases. The mutations were frequently multiple and accompanied by loss of heterozygosity, and there was an association between the number of mutations and the severity of TRI exposure. We observed a specific mutational hot spot at VHL nucleotide 454 in the RCCs of 13 (39%) of the patients, and this mutation was present in adjacent non-neoplastic kidney parenchyma in four of these patients. The nucleotide 454 mutation was neither detected in any of the RCCs from patients without TRI exposure nor in any of the healthy subjects. CONCLUSION: Our results suggest that RCC in patients with high, cumulative TRI exposure is associated with a unique mutation pattern in the VHL gene.

Adolescent↗
PubMed1999

Retraction.

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Retraction Notice↗
PubMed1999

Novel mutations of the MET proto-oncogene in papillary renal carcinomas.

Hereditary papillary renal carcinoma (HPRC) is characterized by multiple, bilateral papillary renal carcinomas. Previously, we demonstrated missense mutations in the tyrosine kinase domain of the MET proto-oncogene in HPRC and a subset of sporadic papillary renal carcinomas. In this study, we screened a large panel of sporadic papillary renal carcinomas and various solid tumors for mutations in the MET proto-oncogene. Summarizing these and previous results, mutations of the MET proto-oncogene were detected in 17/129 sporadic papillary renal carcinomas but not in other solid tumors. We detected five novel missense mutations; three of five mutations were located in the ATP-binding region of the tyrosine kinase domain of MET. One novel mutation in MET, V1110I, was located at a codon homologous to an activating mutation in the c-erbB proto-oncogene. These mutations caused constitutive phosphorylation of MET when transfected into NIH3T3 cells. Molecular modeling studies suggest that these activating mutations interfere with the intrasteric mechanism of tyrosine kinase autoinhibition and facilitate transition to the active form of the MET kinase. The low frequency of MET mutations in noninherited papillary renal carcinomas (PRC) suggests that noninherited PRC may develop by a different mechanism than hereditary papillary renal carcinoma.

3T3 Cells↗
PubMed1998

Bilateral multiple renal oncocytomas and cysts associated with a constitutional translocation (8;9)(q24.1;q34.3) and a rare constitutional VHL missense substitution.

We report here on a patient with bilateral multifocal renal oncocytomas and cysts. Cytogenetic analysis of the patient's lymphocytes revealed a constitutional 46,XY,add (9)(q34.3) karyotype. The rearrangement was further resolved as a constitutional reciprocal t(8;9)(q24.1;q34.3) by microdissection and FISH. Because the 9q breakpoint was located in the same region as the tuberous sclerosis type I locus (TSC1), which is associated with renal tumors, we performed FISH with two TSC1 flanking cosmids that were mapped proximal to the 9q breakpoint, thus excluding its involvement. Loss of heterozygosity (LOH) studies of the tumors revealed LOH in chromosome I, further strengthening the molecular diagnosis of oncocytoma. A previously unreported germline missense substitution, Pro40Arg, in exon I of the VHL gene was also found in the patient's constitutional DNA, adding to the complexity of the genetic profile.

Adenoma, Oxyphilic↗
PubMed1998

Prevalence, morphology and biology of renal cell carcinoma in von Hippel-Lindau disease compared to sporadic renal cell carcinoma.

PURPOSE: Renal cell carcinoma occurs as a sporadic tumor but may be part of the autosomal dominant von Hippel-Lindau disease, characterized by retinal and central nervous system hemangioblastoma, pheochromocytoma, pancreatic cysts and renal cell carcinoma. We determine the prevalence of von Hippel-Lindau disease in a series of unselected renal cell carcinoma cases by molecular genetic analysis, and compare sporadic to von Hippel-Lindau renal cell carcinoma with respect to morphology and biology. MATERIALS AND METHODS: We established registers comprising 63 subjects with von Hippel-Lindau renal cell carcinoma, belonging to 30 distinct families (register A), and 460 unselected patients operated on for renal cell carcinoma in an 11-year period (register B). Molecular genetic analysis of the von Hippel-Lindau gene was performed for living patients of register A, representing 80% of von Hippel-Lindau families, and register B, 62% living patients, to identify von Hippel-Lindau germline mutations. In addition, register B was evaluated by a questionnaire (95% response) for familial occurrence of von Hippel-Lindau disease. RESULTS: The prevalence of von Hippel-Lindau renal cell carcinoma was 1.6% in 189 consenting unselected renal cell carcinoma patients. Risk factors for occult germline von Hippel-Lindau gene mutations in register B included familial renal cell carcinoma in 3 of 3 patients (100%), multifocal or bilateral renal cell carcinoma in 1 of 10 (10%) and age younger than 50 years at diagnosis in 1 of 33 (3%). Compared to sporadic von Hippel-Lindau renal cell carcinoma was characterized by an occurrence 25 years earlier, association with renal cysts, multifocal and bilateral tumors, cystic organization and low grade histology, and a better 10-year survival (p < 0.001 each). In von Hippel-Lindau disease metastases occurred only in tumors larger than 7 cm. CONCLUSIONS: von Hippel-Lindau differs from sporadic renal cell carcinoma in morphology and biology. Our data provide arguments for planning surgery for von Hippel-Lindau renal cell carcinoma and should stimulate future investigations.

Adult↗
PubMed1997

Fixed archival tissue. Purify DNA and primers for good PCR yield!

The analysis of archival formalin-fixed, paraffin-embedded tissue samples becomes increasingly important for molecular biology studies. As fixation and paraffin-embedding cause alterations of proteins and nucleic acids, archival sources of DNA must be handled with care. To address the need for specificity and reproducibility, we developed an improved protocol for semi-automated DNA extraction adapted to fixed, embedded tissue samples, and a PCR approach using HPLC-purified primers.

DNA↗
PubMed1997

Renal cell carcinomas in trichloroethene (TRI) exposed persons are associated with somatic mutations in the von Hippel-Lindau (VHL) tumour suppressor gene.

Renal cell carcinomas (RCC) develop as a consequence of somatic mutations of the von Hippel-Lindau (VHL) tumour suppressor gene. Recent epidemiological studies show that high and prolonged occupational exposures to trichloroethene (TRI) are associated with an increased incidence of RCC. Tumour tissues from 23 RCC patients with occupational histories of very high TRI exposure were analysed for somatic mutations within the VHL gene. DNA was isolated from microdissected tumour cells, amplified by polymerase chain reaction (PCR), and analysed in single strand conformation polymorphism (SSCP) and sequencing. RCC tissues of all 23 TRI exposed persons analysed thus far showed aberrations of the VHL gene, with 30% having aberrations in exon 1, 44% in exon 2, and 26% in exon 3. By comparison to much lower reported VHL mutation frequencies of 33-55% in TRI-unexposed RCC patients, these results indicate a specifically high mutation frequency at the VHL gene in TRI-exposed RCC patients; four of these aberrations have thus far been confirmed as VHL mutations by sequence analysis. This finding indicates the VHL gene being a susceptible and specific target in TRI induced renal carcinogenesis. Furthermore, the frequent involvement of exon 2 identifies potential 'hot spots' for this carcinogen. In addition to the available epidemiological studies the results are now further proof for human renal carcinogenicity induced by high occupational exposures to TRI.

Aged↗
PubMed1997

p53 alterations in thymic epithelial tumours.

The prognosis of thymic epithelial tumours depends on malignant behaviour that cannot always be predicted on histological grounds. This study aimed at identifying a molecular marker that would be useful in overcoming the drawbacks of histopathology. Forty-four thymic epithelial tumours were analysed for alterations of the tumour suppressor gene p53 using immunohistochemistry (antibodies D0-1 and CM-1) and PCR-based single-strand conformation polymorphism and DNA sequencing. Histological and clinical evaluation and also p53 analysis revealed three major tumour groups: non-organotypic thymic carcinomas with frequent p53 alterations (7/9) and occurrence of p53 gene mutations (2/9); malignant thymomas with frequent p53 alterations but without p53 gene mutations (11/18); and benign thymomas with rare p53 alterations and without p53 gene mutations (2/17). In non-organotypic thymic carcinomas p53 was detected with both antibodies. In contrast, thymomas lacked immunoreaction with D0-1 suggesting alteration of the antibody-binding site. Overall immunohistochemical results correlated with clinical stages (P < 0.01), pathohistology (P < 0.01), and survival times (P < 0.05). We consider immunohistochemical p53 detection to be a useful new prognostic factor for the evaluation of thymic epithelial tumours.

Adult↗
PubMed1997

Germline and somatic mutations in the tyrosine kinase domain of the MET proto-oncogene in papillary renal carcinomas.

Hereditary papillary renal carcinoma (HPRC) is a recently recognized form of inherited kidney cancer characterized by a predisposition to develop multiple, bilateral papillary renal tumours. The pattern of inheritance of HPRC is consistent with autosomal dominant transmission with reduced penetrance. HPRC is histologically and genetically distinct from two other causes of inherited renal carcinoma, von Hippel-Lindau disease (VHL) and the chromosome translocation (3;8). Malignant papillary renal carcinomas are characterized by trisomy of chromosomes 7, 16 and 17, and in men, by loss of the Y chromosome. Inherited and sporadic clear cell renal carcinomas are characterized by inactivation of both copies of the VHL gene by mutation, and/or by hypermethylation. We found that the HPRC gene was located at chromosome 7q31.1-34 in a 27-centimorgan (cM) interval between D7S496 and D7S1837. We identified missense mutations located in the tyrosine kinase domain of the MET gene in the germline of affected members of HPRC families and in a subset of sporadic papillary renal carcinomas. Three mutations in the MET gene are located in codons that are homologous to those in c-kit and RET, proto-oncogenes that are targets of naturally-occurring mutations. The results suggest that missense mutations located in the MET proto-oncogene lead to constitutive activation of the MET protein and papillary renal carcinomas.

Adult↗
PubMed1997

Sporadic pheochromocytomas are rarely associated with germline mutations in the vhl tumor suppressor gene or the ret protooncogene.

Pheochromocytoma is a tumor that may occur sporadically or may be a manifestation of a hereditary disease, such as von Hippel-Lindau disease (VHL) and multiple endocrine neoplasia (MEN) type 2. As patients with VHL or MEN type 2 are at risk to develop multiple tumors, they must be distinguished from sporadic cases. We determined the incidence of VHL and MEN type 2 among 62 German patients diagnosed with pheochromocytoma without a history of a hereditary disease. Germline analyses of the vhl gene and exons 10, 11, and 13 of the ret protooncogene were performed by PCR, single strand conformation polymorphism, enzyme digestion, or sequencing. Two patients (3%) showed vhl mutations (95% confidence interval, 1-11%). One patient showed loss of the MspI restriction site at nucleotides 712/713. Another patient had a C/T change at an intronic site that was also detected in 2 of his offspring. No mutations were detected in the ret protooncogene (97.5% confidence interval, 0-6%). In Germany, most sporadic pheochromocytomas are not due to VHL or MEN type 2. Therefore, clinical work-up in patients with pheochromocytoma without signs of hereditary disease is not recommended. However, because the costs of genetic screening are relatively low, and each index case allows optimal care for family members, molecular testing might be cost-effective.

Adolescent↗
PubMed1997

German family study on hereditary breast and/or ovarian cancer: germline mutation analysis of the BRCA1 gene.

Women harboring BRCA1 germline mutations carry an 85% lifetime risk of developing breast cancer and a 63% risk of ovarian cancer. In this first systematic study of familial breast and/or ovarian cancer in Germany we investigated 29 families for germline mutations in the BRCA1 gene. We identified mutations in three breast cancer families and in four breast-ovarian cancer families. The mutations include one missense mutation, one frameshift mutation, one splice mutation, and four nonsense mutations cosegregating with breast and/or ovarian susceptibility in five of ten (50%) families showing positive evidence of linkage to chromosome band 17q21 and in two of 19 (11%) families where linkage data was not available. Two apparently unrelated families carried the same nonsense mutation at codon 1835 and three families harbored a C to T transition at nucleotide 49 of the untranslated exon 4. Allelotyping of the markers D17S855, D17S1322, D17S1323, and D17S1327 located within or near BRCA1 revealed that all affected individuals in the two families harboring the mutation at codon 1835 shared at least one allele indicating a founder mutation. With respect to the overall mutation spectrum, no mutations were identified in exon 11 (0/7) in this set of German families. These findings differed significantly from those in British (17/32)(P = 0.012) and Southern Swedish (13/15) (P < 0.001) families. The lack of BRCA1 mutations in exon 11 which represents 61% of the entire coding sequence may provide additional insight into BRCA1 associated breast and ovarian tumor development.

BRCA1 Protein↗
PubMed1996

Allelic losses at chromosomes 1p, 2p, 6p, 10p, 13q, 17p, and 21q significantly correlate with the chromophobe subtype of renal cell carcinoma.

We analyzed 50 sporadic renal cell carcinomas (RCCs) for loss of heterozygosity (LOH) at the chromosomal regions 1p, 2p, 6p, 7q, 10p, 11p, 13q, 14q, 17p, 21q, and 22q. Histologically, the tumors were distinguished into clear cell, chromophilic, and chromophobe carcinomas. Whereas LOH at 14q was identified in 42-64% of all three tumor types, only the chromophobe tumors showed high frequencies of LOH (73-91%) at 1p, 2p, 6p, 10p, 13q, 17p, and 21q. These findings provide substantial evidence that the chromophobe subtype of RCC represents a distinct genetic entity. Thus, specific LOH patterns may define the histogenesis and oncogenesis of chromophobe RCC and may be useful in tumor diagnosis and clinical prognosis.

Adenocarcinoma↗
PubMed1996

Germline mutations in the Von Hippel-Lindau disease (VHL) gene in families from North America, Europe, and Japan.

Germline mutation analysis was performed in 469 VHL families from North America, Europe, and Japan. Germline mutations were identified in 300/469 (63%) of the families tested; 137 distinct intragenic germline mutations were detected. Most of the germline VHL mutations (124/137) occurred in 1-2 families; a few occured in four or more families. The common germline VHL mutations were: delPhe76, Asn78Ser, Arg161Stop, Arg167Gln, Arg167Trp, and Leu178Pro. In this large series, it was possible to compare the effects of identical germline mutations in different populations. Germline VHL mutations produced similar cancer phenotypes in Caucasian and Japanese VHL families. Germline VHL mutations were identified that produced three distinct cancer phenotypes: (1) renal carcinoma without pheochromocytoma, (2) renal carcinoma with pheochromocytoma, and (3) pheochromocytoma alone. The catalog of VHL germline mutations with phenotype information should be useful for diagnostic and prognostic studies of VHL and for studies of genotype-phenotype correlations in VHL.

Adrenal Gland Neoplasms↗
PubMed1996

Detection of a germline mutation and somatic homozygous loss of the von Hippel-Lindau tumor-suppressor gene in a family with a de novo mutation. A combined genetic study, including cytogenetics, PCR/SSCP, FISH, and CGH.

von Hippel-Lindau (VHL) disease is a pleiotropic disorder featuring a variety of malignant and benign tumors of the eye, central nervous system, kidney, and adrenal gland. Recently the VHL gene has been identified in the chromosomal region 3p25-26. Prognosis and successful management of VHL patients and their descendants depend on unambiguous diagnosis. Due to recurrent hemangioblastomas, a29-year-old patient without familial history of VHL disease was diagnosed to be at risk for the disease. Histopathological examination of a small renal mass identified a clear cell tumor with a G1 grading. Genetic characterization of the germline and of the renal tumor was performed. Polymerase chain reaction/single strand conformation polymorphism (PCR/SSCP) analysis with primers from the VHL gene identified a deletion of a single nucleotide in exon 2 in the patient's germline and in the tumor, but not in the DNA of his parents. This deletion therefore must be a de novo mutation. Comparative genome hybridization (CGH) and fluorescence in situ hybridization (FISH) analysis of the G1 tumor with differentially labelled yeast artifical chromosome (YAC) clones showed loss of 3p and of the 3p26 signals, respectively. In conclusion, we identified a de novo germline mutation in the VHL gene of a young patient and a somatic chromosome 3p loss at the homologous chromosome 3 in his renal tumor. Our results suggest a recessive mode of inactivation of the VHL gene, providing solid evidence for its tumor-suppressor gene characteristics. Our data show the diagnostic potential of genetic testing, especially in patients without VHL family history. Furthermore, the findings of homozygous inactivation of the VHL gene in a G1 tumor support the notion that the inactivation of the VHL gene is an early event in tumorigenesis of renal cell carcinoma.

Adult↗
PubMed1996

Mutations in the VHL tumor suppressor gene and associated lesions in families with von Hippel-Lindau disease from central Europe.

von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome predisposing to retinal, cerebellar and spinal hemangioblastoma, renal cell carcinoma (RCC), pheochromocytoma and pancreatic tumors. Clinically two types of the disease can be distinguished: VHL type 1 (without pheochromocytoma) and VHL type 2 (with pheochromocytoma). We report VHL germline mutations and trends in phenotypic variation in families from central Europe. We identified 28 mutations in 53/65 (81.5%) families with 18 (64%) mutations being unique to this population. Whereas types and distribution of mutations as well as a strong correlation of missense mutations with the VHL 2 phenotype were similar to those identified in other populations, these families have provided new insights into the molecular basis for variability in the VHL 2 phenotype. Seven different missense mutations in exons 1 and 3 varied in their biological consequences from a minimal VHL 2 phenotype with pheochromocytoma only to a full VHL 2 phenotype with RCC and pancreatic lesion. These findings contribute to a better understanding of the fundamental mechanisms of VHL disease and its phenotypic variability. Further, we have provided rapid VHL screening for the families in central Europe, which has resulted in improved diagnosis and clinical management.

Base Sequence↗