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S Scherneck

Publications and source records attributed to S Scherneck.

At least 37 records · Page 2Linked to original sources
PubMed1999

Yeast cells allow high-level expression and formation of polyomavirus-like particles.

Polyomavirus-derived virus-like particles (VLPs) have been described as potential carriers for encapsidation of nucleic acids in gene therapy. Although VLPs can be generated in E. coli or insect cells, the yeast expression system should be advantageous as it is well established for the biotechnological generation of products for human use, especially because they are free of toxins hazardous for humans. We selected the yeast Saccharomyces cerevisiae for expression of the major capsid protein VP1 of a non-human polyomavirus, the hamster polyomavirus (HaPV). Two entire HaPV VP1-coding sequences, starting with the authentic and a second upstream ATG, respectively, were subcloned and expressed to high levels in Saccharomyces cerevisiae. The expressed VP1 assembled spontaneously into VLPs with a structure resembling that of the native HaPV capsid. Determination of the subcellular localization revealed a nuclear localization of some particles formed by the N-terminally extended VP1, whereas particles formed by the authentic VP1 were found mainly in the cytoplasmic compartment.

Animals↗
PubMed1999

Microsatellite alterations in serum DNA of patients with colorectal cancer.

Cell-free DNA in the blood of cancer patients has been shown to harbor microsatellite alterations frequently matching those of the primary tumors. The aim of this study was to assess the prevalence of allelic loss and instability of serum DNA microsatellites in colorectal cancers. DNA extracted from preoperative sera and microdissected tumors of 27 patients with colorectal adenocarcinoma were allelotyped for nine markers on chromosome arms 1p, 5q, 8p, 12p, 15q, 17p, 17q, and 18q. In all tumors, expression of MLH1 and MSH2 was explored immunohistochemically. Microsatellite alterations comprising loss of heterozygosity (LOH) or microsatellite instability (MSI) were present in 26 of 27 (96%) tumors and in 16 of 27 (59%) serum samples. Using stringent criteria, serum MSI was significantly (p < 0.02) more detectable than serum LOH. Of the three patients with high-grade MSI (more than two unstable loci) present in tumor and serum DNA, two had MSH2-negative tumors on immunohistochemical testing. No significant association of tumor stage or clinical outcome with serum microsatellite alterations of LOH or MSI type could be demonstrated. Although the DNA-shedding phenotype of tumors remains to be elucidated, its detection by serum DNA microsatellite analysis seems to be useful for the diagnosis and monitoring of neoplasms, including colorectal cancers with and without MSI.

Adenocarcinoma↗
PubMed1998

Multifactorial analysis of differences between sporadic breast cancers and cancers involving BRCA1 and BRCA2 mutations.

BACKGROUND: We have previously demonstrated that breast cancers associated with inherited BRCA1 and BRCA2 gene mutations differ from each other in their histopathologic appearances and that each of these types differs from breast cancers in patients unselected for family history (i.e., sporadic cancers). We have now conducted a more detailed examination of cytologic and architectural features of these tumors. METHODS: Specimens of tumor tissue (5-microm-thick sections) were examined independently by two pathologists, who were unaware of the case or control subject status, for the presence of cell mitosis, lymphocytic infiltration, continuous pushing margins, and solid sheets of cancer cells; cell nuclei, cell nucleoli, cell necrosis, and cell borders were also evaluated. The resulting data were combined with previously available information on tumor type and tumor grade and further evaluated by multifactorial analysis. All statistical tests are two-sided. RESULTS: Cancers associated with BRCA1 mutations exhibited higher mitotic counts (P = .001), a greater proportion of the tumor with a continuous pushing margin (P<.0001), and more lymphocytic infiltration (P = .002) than sporadic (i.e., control) cancers. Cancers associated with BRCA2 mutations exhibited a higher score for tubule formation (fewer tubules) (P = .0002), a higher proportion of the tumor perimeter with a continuous pushing margin (P<.0001), and a lower mitotic count (P = .003) than control cancers. CONCLUSIONS: Our study has identified key features of the histologic phenotypes of breast cancers in carriers of mutant BRCA1 and BRCA2 genes. This information may improve the classification of breast cancers in individuals with a family history of the disease and may ultimately aid in the clinical management of patients.

Adult↗
PubMed1998

Consortium study on 1280 breast carcinomas: allelic loss on chromosome 17 targets subregions associated with family history and clinical parameters.

The pattern of loss of heterozygosity (LOH) on chromosome 17 in human breast cancer is complicated and shows many different regions of loss. In an attempt to narrow down the relevant regions of LOH on chromosome 17, we have studied the deletion pattern and its association with clinical parameters in 1280 breast carcinoma-venous blood lymphocyte pairs. In total, 42 different chromosome 17 loci were investigated, and between 25 and 625 cases were analyzed at each locus. The frequency of LOH observed on the p arm was much higher than that observed on the q arm. The opposite effect was observed in 52 ovarian cancer cases investigated, with less LOH on 17p than on 17q. Patterns of loss consistent with interstitial and terminal deletions, as well as loss of either the p or q arm or monosomy 17 were observed. To determine whether loss at particular loci may be associated with biological features of breast tumors, clinical data including age of onset, family history of breast cancer, tumor histopathology, tumor size, estrogen receptor (ER) status, and occurrence of lymph node or distant metastases were collected for each case. Overall, large-sized, ER-negative, lymph node-positive ductal tumors showed the highest frequencies of LOH, with ER-negative and ductal tumors showing LOH for markers along the majority of the chromosome. Eight regions of chromosome 17 appear to be associated with human breast cancer, two on 17p and six on 17q. These regions were not necessarily in the areas exhibiting the highest frequencies of LOH but were defined by interstitial and terminal deletions in multiple independent cases. Seven of these regions showed statistically significant differences in LOH associated with clinical parameters. These data strongly suggest that loci on chromosome 17 may determine aspects of tumor presentation and disease behavior in human breast cancer and pinpoint candidate tumor suppressor gene loci.

Adult↗
PubMed1998

Detection of 6q deletions in breast carcinoma cell lines by fluorescence in situ hybridization.

Dual-color fluorescence in situ hybridization was performed to detect the frequency and extent of 6q deletions in ten breast carcinoma cell lines. In five cell lines, the 6q deletions involved large regions extending from 6q12-q16 to 6q27, and in one the deletion extended from the region distal to YAC 751G10 at 6q25.1 to 6q27. In two cell lines, 6q deletions occurred only in cells with polysomy 6, indicating that such deletions might be secondary chromosomal aberrations and reflect late genetic changes in breast carcinomas. In addition, an overrepresentation of 6q21-q22.2 was detected in one cell line.

Aneuploidy↗
PubMed1998

Genetic heterogeneity and penetrance analysis of the BRCA1 and BRCA2 genes in breast cancer families. The Breast Cancer Linkage Consortium.

The contribution of BRCA1 and BRCA2 to inherited breast cancer was assessed by linkage and mutation analysis in 237 families, each with at least four cases of breast cancer, collected by the Breast Cancer Linkage Consortium. Families were included without regard to the occurrence of ovarian or other cancers. Overall, disease was linked to BRCA1 in an estimated 52% of families, to BRCA2 in 32% of families, and to neither gene in 16% (95% confidence interval [CI] 6%-28%), suggesting other predisposition genes. The majority (81%) of the breast-ovarian cancer families were due to BRCA1, with most others (14%) due to BRCA2. Conversely, the majority of families with male and female breast cancer were due to BRCA2 (76%). The largest proportion (67%) of families due to other genes was found in families with four or five cases of female breast cancer only. These estimates were not substantially affected either by changing the assumed penetrance model for BRCA1 or by including or excluding BRCA1 mutation data. Among those families with disease due to BRCA1 that were tested by one of the standard screening methods, mutations were detected in the coding sequence or splice sites in an estimated 63% (95% CI 51%-77%). The estimated sensitivity was identical for direct sequencing and other techniques. The penetrance of BRCA2 was estimated by maximizing the LOD score in BRCA2-mutation families, over all possible penetrance functions. The estimated cumulative risk of breast cancer reached 28% (95% CI 9%-44%) by age 50 years and 84% (95% CI 43%-95%) by age 70 years. The corresponding ovarian cancer risks were 0.4% (95% CI 0%-1%) by age 50 years and 27% (95% CI 0%-47%) by age 70 years. The lifetime risk of breast cancer appears similar to the risk in BRCA1 carriers, but there was some suggestion of a lower risk in BRCA2 carriers <50 years of age.

Adult↗
PubMed1998

[PTEN/MMAC1 is apparently not a relevant tumor suppressor gene in development of hereditary breast carcinoma].

In order to clarify the role of the recently discovered tumour suppressor gene PTEN/MMAC1 in hereditary breast cancer, we screened the DNA from members of 10 families with demonstrated hereditary breast cancer for mutations through direct sequencing. Since we could not find any relevant alterations, although further investigations are necessary, PTEN/MMAC1 seems not to play a relevant role in the genesis of hereditary breast cancer.

Breast Neoplasms↗
PubMed1997

Strong indication for a breast cancer susceptibility gene on chromosome 8p12-p22: linkage analysis in German breast cancer families.

Chromosomal losses involving the short arm of chromosome 8 are frequent in a variety of tumor types, including breast cancer, suggesting the presence of one or more tumor suppressor genes in this region. Previous linkage analysis and studies of loss of heterozygosity (LOH) have suggested the presence of a putative third breast cancer susceptibility gene around D8S505 at 8p12-p22. We have performed linkage analysis in two German breast cancer families, showing negative lod scores with 17q and 13q markers, using seven adjacent microsatellite markers from 8p12-p22. Incorporating LOH data from tumors of the affected family members a maximum cumulative three-point lod score of 3.30 at theta = 0.00 was obtained with D8S137 and D8S131. Our findings considerably strengthen the evidence for a third breast cancer susceptibility locus (BRCA3) mapping to the short arm of human chromosome 8.

Adult↗
PubMed1997

BRCA1 mutations and phenotype.

More than 100 mutations have been described for the breast-cancer-susceptibility gene BRCA1. The paper describes phenotypical aspects of three selected mutations located at the beginning, in the middle, and at the end of the gene. A remarkable decrease of the age of diagnosis of the mammary carcinoma is observed with increasing length of the putative gene product, combined with greater severity of the disease.

Adult↗
PubMed1997

Generation of lymphoma-type variant hamster polyomavirus genomes in hamsters susceptible to lymphoma induction.

The hamster polyomavirus (HaPV) induces either hair follicle epitheliomas or lymphomas in either Z3 or HaP respectively. Syrian hamsters. In the lymphomas specifically deleted "lymphoma-type" (lt) HaPV genomes are accumulated. In the present study the temporal pattern of generation of HaPV (lt) DNA was investigated in context of the development of lymphomas in neonatally infected HaP hamsters. The generation of HaPV (lt) DNA was first detectable during the postnatal phase of high level replication of viral DNA in hemopoietic organs (at 7 days post infection), thus clearly preceding the development of overt lymphoma. A variety of HaPV (lt) DNA species is generated in lymphoid cells, but usually only one of them is accumulated to high amounts in lymphoma cells. Furthermore, the pattern of HaPV (lt) and wild-type (wt) DNA was studied in normal and tumor tissues of tumor-bearing hamsters as well as in tumor-free hamsters. In tumor-bearing hamsters predominantly HaPV (lt) DNA species were found in the infected tissues, while HaPV (wt) DNA was detected rarely and only in tumor-free tissues. In contrast, in tissues of tumor-free hamsters HaPV (wt) DNA prevailed over HaPV (lt) DNA species.

Animals↗
PubMed1997

Deletion mapping and linkage analysis provide strong indication for the involvement of the human chromosome region 8p12-p22 in breast carcinogenesis.

We have identified a high frequency of loss of heterozygosity (LOH) on the human chromosome region 8p12-p22 in a panel of microdissected familial (86% LOH) and sporadic (74% LOH) breast tumours. The two most frequently deleted regions were defined around marker D8S133 and in a broader centromeric region bounded by markers D8S137 and D8S339. We cannot unequivocally characterize the 8p12-p22 loss as an early or a late event in breast carcinogenesis. In parallel, we have performed linkage analysis in four German breast cancer families. A location score greater than 13.67 corresponding to a LOD score of 2.97 at the marker D8S137 has been obtained. Our results considerably strengthen the evidence for a breast cancer susceptibility gene(s) located on the short arm of the chromosome region at 8p12-p22.

Adult↗
PubMed1997

Loss of heterozygosity at 7q31 in breast cancer: results from an International Collaborative Study Group. The Breast Cancer Somatic Genetics Consortium.

Loss of heterozygosity (LOH) at 7q31 has been claimed to occur in over 80% of all breast cancers and to be of prognostic significance. This would make this genetic alteration the most common event observed in breast cancer to date. Others, however, have been unable to confirm this high incidence. In this multicenter study, we have complied LOH scorings for three polymorphic markers for 7q31-q32 in 683 breast tumors. Although some significant differences between centers existed, no center reported more than 40% LOH, and the average rate was 19%. Disease-free and overall survival of the patients whose tumors carried LOH at 7q31 did not differ significantly from those patients whose tumors showed retention of heterozygosity at 7q31. In a double-blind scoring of a subset of the raw data, an average discordant rate of LOH scoring of 12% was observed. While startling in itself, this was unable to explain the variation among centers, nor the difference with the initially reported high rate of LOH. We conclude that LOH at 7q31 is not important as a genetic alteration in breast cancer as originally suggested, nor a strong determinant of disease outcome.

Breast Neoplasms↗
PubMed1996

BRCA1 mutations in German breast-cancer families.

We analyzed germline mutations of the BRCA1 gene in 20 German breast/ovarian-cancer families. BRCA1 mutations co-segregating with breast-cancer susceptibility were identified in 3 of these families. All mutations were found to generate a premature stop codon leading to the synthesis of truncated BRCA1 proteins of different length. Nine polymorphisms were detected in BRCA1, 4 of which have not been described previously. Analysis of familial tumors for LOH revealed that only the disease-related allele of BRCA1 was present.

Adult↗
PubMed1996

A defined chromosome 6q fragment (at D6S310) harbors a putative tumor suppressor gene for breast cancer.

Recent evidence obtained by cytogenetic and molecular studies indicates that in breast cancer chromosome 6q is often affected by genetic changes suggesting the existence of putative tumor suppressor genes (TSGs). However the function of gene(s) on this chromosome in breast cancer suppression is not understood. To substantiate further the presence of breast cancer related TSGs at 6q and to define their location, we first performed microcell-mediated transfer of chromosome 6 to CAL51 breast cancer cells for studying possible suppression of malignant phenotype and secondly, we analysed DNAs from 46 primary breast cancers for loss of constitutive heterozygosity (LOH) using 24 poly-morphic microsatellite markers. The chromosome transfer resulted in loss of tumorigenicity and reversion of other neoplastic properties of the microcell hybrids. Polymorphism analysis of single hybrids revealed that they harbored only a small donor chromosome fragment defined by the marker D6S310 (6q23.3-q25) and flanked by D6S292 and D6S311. The LOH data suggest that four tumor suppressor gene loci mapped to the central and distal portion of 6q may be independently deleted in breast cancer. One of these regions corresponds to the region identified by chromosome transfer.

Breast Neoplasms↗
PubMed1996

Hamster polyomavirus-encoded proteins: gene cloning, heterologous expression and immunoreactivity.

The hamster polyomavirus (HaPV) is associated with spontaneously appearing skin epithelioma of the Syrian hamster Z3 strain. Virus particles prepared from the skin epithelioma cause lymphoma and leukemia when injected into newborn hamsters from a distinct Syrian hamster colony (HaP); in contrast to the skin epithelioma the hemopoietic tumors are virus free but accumulate viral DNA. To study the humoral immune response of HaPV-infected Z3 hamsters we produced recombinant HaPV proteins in Escherichia coli as beta-galactosidase-, TrpE- and dihydrofolate reductase-fusion proteins or as non-fused proteins. Recombinant plasmids carried segments of all putative early and late HaPV proteins. The recombinant proteins were detected in stained SDS polyacrylamide gels and in Western blots using monoclonal anti-TrpE and anti-beta-galactosidase antibodies and sera of HaPV-infected hamsters. Sera from HaPV-infected Z3 hamsters and crude lysates of all clones were applied to Western blots to characterize the humoral immune response in the animals. HaPV-specific antibodies were found to be directed against early protein segments translated from the first common exon and from the second unique exon of LT and MT, resp., as well as against the late proteins VP1 and VP2/3. The almost complete VP2 was recognized by all sera whereas VP1 was detected only by a half of the sera. Our data suggest the presence of at least 2 immunodominant regions in VP2, one in the C-terminal VP1 and at least 4 in early proteins.

Animals↗
PubMed1996

BRCA1 mutation update and analysis.

The discovery of the BRCA1 gene involved in the development of human hereditary breast cancer led to extensive international efforts to identify the mutations leading to the disease. The new listing covers 127 mutations published in the indicated papers before 30 April 1996; 55% of the mutations are localized in exon 11, followed by exons 2 (5.5%), 5 and 16 (4.7% each).

Exons↗