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Biomedical subjects

B Zbar

Publications and source records attributed to B Zbar.

At least 109 records · Page 6Linked to original sources
PubMed1993

Physical mapping of chromosome 3p25-p26 by fluorescence in situ hybridisation (FISH).

As part of our effort to isolate and characterise the von Hippel-Lindau (VHL) disease gene, we constructed a physical map of chromosome 3p25-26 by fluorescence in situ hybridisation (FISH) studies on a panel of cytogenetic rearrangements involving this region. Biotinylated cosmid and lambda probes were hybridised to metaphase chromosome spreads and positioned with respect to each cytogenetic breakpoint. These studies unequivocally established the order of five loci linked to the VHL disease gene: cen-(RAF1,312)-D3S732-D3S1250-D3S601-D3S18 -pter and determined the position of three other probes within this map. These results ordered RAF1 and D3S732 for the first time, confirmed the localisation of D3S1250 between RAF1 and D3S601 and determined the position of D3S651 with respect to other chromosome 3p25-p26 loci. The establishment of an ordered set of cytogenetic aberrations will enable the rapid assignment of polymorphic and nonpolymorphic cloned sequences within the chromosome region 3p25-p26.

Cell Line, Transformed↗
PubMed1993

Mapping the Von Hippel-Lindau disease tumour suppressor gene: identification of germline deletions by pulsed field gel electrophoresis.

Von Hippel-Lindau (VHL) disease is a dominantly inherited familial cancer syndrome in which affected individuals have a greatly increased predisposition to the development of haemangioblastomas of the central nervous system and retina, renal cell carcinoma and phaeochromocytoma. The VHL gene has been mapped to chromosome 3p25-p26 by genetic linkage studies and we have previously demonstrated that the VHL gene is tightly linked to the D3S601 locus (Zmax = 18.86 at theta = 0.0) suggesting that D3S601 maps close to the VHL disease gene. We have constructed a long range physical map around D3S601 and screened 91 VHL patients from 80 kindreds for germline rearrangements using pulsed field gel electrophoresis. Two patients showed abnormal fragments in Mlul digested DNA probed with D3S601. Further analysis was consistent with both patients having germline deletions (approximately 120 kb and 50 kb) telomeric to D3S601. These results have (i) established the position of the VHL disease gene with respect to D3S601, (ii) refined the localisation of the VHL disease gene to a small region (approximately 50 kb) of chromosome 3p25-p26 and (iii) excluded the plasma membrane Ca(+)+-transporting ATPase isoform 2 (PMCA-2) gene as a candidate gene for VHL disease.

Chromosome Mapping↗
PubMed1993

Molecular genetic studies of sporadic and familial renal cell carcinoma.

Renal cell carcinoma (RCC) occurs predominantly as a sporadic disease but has familial forms. Cytogenetic and DNA deletion analyses show that both sporadic and familial RCC tumors arise as the result of chromosomal deletions in the 3p13-p26 region. von Hippel-Lindau (VHL) disease is a hereditary, multifocal syndrome that includes, among several affected organs, multiple, bilateral renal cysts and RCC. Although the VHL disease gene maps to chromosome 3p25-p26, data indicate that the VHL and sporadic RCC disease genes are likely to be independent. The authors hypothesize that VHL disease manifestations are controlled by mutations in the VHL disease gene and that the onset of VHL-associated kidney cancer is due to a second mutation of the linked sporadic RCC gene.

Carcinoma, Renal Cell↗
PubMed1992

Distinct hypermethylation patterns occur at altered chromosome loci in human lung and colon cancer.

Regional increases in DNA methylation occur in normally unmethylated cytosine-rich areas in neoplastic cells. These changes could potentially alter chromatin structure to inactivate gene transcription or generate DNA instability. We now show that, in human lung and colon cancer DNA, hypermethylation of such a region consistently occurs on chromosome 17p in an area that is frequently reduced to homozygosity in both tumor types. Over the progression stages of colon neoplasia, this methylation change increases in extent and precedes the allelic losses on 17p that are characteristic of colon carcinomas. We also show on chromosome 3p that regional hypermethylation may nonrandomly accompany chromosome changes in human neoplasia. Increased methylation is consistent in small-cell lung carcinoma DNA at two 3p loci that are constantly reduced to homozygosity in this tumor, but it is not seen in colon cancer DNA, in which these loci are infrequently structurally altered.

Carcinoma↗
PubMed1992

Molecular and cellular characterization of human renal cell carcinoma cell lines.

Recent studies have suggested that a tumor suppressor gene located in the region 3p21-26 of chromosome 3 is essential to the genesis of sporadic renal cell carcinoma (RCC) and that other tumor suppressor genes located on other chromosomes may be involved with progression of this malignancy. The cellular heterogeneity of solid tumors complicates their analysis. In order to analyze a homogeneous population of tumor cells and identify genetic changes associated with histology in renal cortical tumors, we have established and characterized 35 RCC lines derived from tumor tissue from 31 patients with renal cell carcinomas. The overall success rate in establishing these cell lines from fresh or frozen specimens was 75% (18 of 24) and 35% (17 of 48), respectively. These lines differed in their morphology, growth rates, and tumorigenicity in athymic nude mice. Molecular characterization utilizing DNA fingerprinting and restriction fragment length polymorphism deletion analysis was performed to detect somatic mutations and loss of heterozygosity on the short arm of chromosome 3. Analysis revealed loss of heterozygosity on chromosome 3p in 25 cell lines derived from 28 informative nonpapillary forms of RCC (89%). Deletion-mapping analysis showed the retention of the distal locus, D3S18, in one of the RCC cell lines, which further localized the position of the putative tumor suppressor gene to the region proximal to D3S18. Although deletions on chromosome 3 have been recently suggested to be specific to the clear cell-type phenotype, our results revealed no correlation between loss of heterozygosity and clear or granular cell types.

Animals↗
PubMed1992

Molecular characterization of a large homozygous deletion in the small cell lung cancer cell line U2020: a strategy for cloning the putative tumor suppressor gene.

Homozygous deletions are instrumental in the detection and cloning of tumor suppressor genes. We report the isolation and characterization of 39 new single-copy probes saturating a submicroscopic homozygous deletion detected in the DNA of the small cell lung cancer (SCLC) cell line U2020. The probes were selected from a large collection, covering the entire length of chromosome 3 with an estimated average spacing of 100-150 kb. Based on the number of probes in the deletion and the probe density, the size of the U2020 submicroscopic deletion was estimated to be in the range of 4-7 megabases. Among the deleted loci, 17 showed conservation across species, probably representing potential coding gene sequences. By genetic and physical mapping of a large randomly chosen fraction of the deleted probes, we defined the location of the U2020 deletion within chromosome band 3p12. Our cloning strategy is based on narrowing the region of interest by eliminating probes that retain heterozygosity in SCLC samples, thus selecting for probes in the region of common loss.

Blotting, Southern↗
PubMed1992

The biology and genetics of hereditary cancers.

Hereditary cancer syndromes are generally produced by the inheritance of a single mutant gene. New tools have been developed that enable research workers to locate the defective genes responsible for the inherited forms of cancer. Once a disease gene has been localized, it may be possible to identify individuals who have inherited the disease gene before cancer develops.

Gene Expression↗