Biomedical subjects

A R Brothman

Publications and source records attributed to A R Brothman.

At least 37 records · Page 2Linked to original sources

PubMed1998

Chromosome 7 abnormalities in prostate cancer detected by dual-color fluorescence in situ hybridization.

Aneusomy of chromosome 7 and loss at 7q (especially 7q31.1) have been reported in prostate cancer. To further investigate abnormalities of 7q and the relationship with whole chromosome 7 changes, we have conducted a dual-color fluorescence in situ hybridization (FISH) analysis on isolated nuclei from 28 primary prostate cancers. A pericentromeric probe for chromosome 7, five newly isolated sequence-specific bacterial artificial chromosome (BAC) probes from 7q31.1, and one BAC for the epidermal growth factor receptor (EGFR) gene at 7p12 were used in dual color hybridizations. Pericentromeric probes for chromosomes X and 4 were also used as controls. Sixteen (57.1%) of the 28 tumors showed clonal aberrations. Nine of them were trisomy 7 and four were hypertetrasomy for chromosome 7. Deletions at 7q31.1 were found in two of the high grade tumors. With the exception of these two cases, all other cases showed concordant results using all probes. These findings confirm previous studies that aneusomy of 7 is associated with prostate cancer progression, and there may be a tumor suppressor gene (TSG) at 7q31.1 which is associated with tumor progression. In addition, our study indicates: (1) the deletion pattern of individual nuclei infers that deletions at 7q31.1 precede reduplications of chromosome 7; and (2) the amplification of EGFR was not detected at the DNA level, suggesting that activation of this oncogene may play a minor role in prostate cancer.

Aneuploidy↗

PubMed1998

Commonly occurring loss and mutation of the MXI1 gene in prostate cancer.

One of the most common chromosomal abnormalities in prostate cancer involves loss of 10q22-qter. Rarely, a smaller deletion, involving 10q24-q25, has been observed, suggesting the presence of a tumor suppressor gene at this site. We previously demonstrated that the MXI1 gene maps to 10q24-q25 and is mutated in some tumors with cytogenetically detectable deletions of this locus. MXI1 encodes a basic-helix-loop-helix protein that suppresses the transcriptional activity of the MYC oncoprotein by competing for the common dimerization partner, MAX, and binding to identical DNA sites. Because more than 90% of prostate tumors contain no cytogenetic abnormality of 10q, the relevance of MXI1 loss and/or mutation to the vast majority of cases remains unclear. We prospectively evaluated prostate tumors for loss of MXI1 by fluorescence in situ hybridization (FISH) and cytogenetic techniques. Twenty-one of 40 tumors (53%) demonstrated loss of a single MXI1 allele as determined by FISH. Ten cases with cytogenetically normal 10qs, but with FISH-documented deletion of MXI1, were examined at the molecular level, and eight mutations were identified, albeit at low frequency. Five of the mutant proteins were unable to bind DNA in association with MAX. We conclude that MXI1 gene loss in prostate cancer is common and most frequently involves a cytogenetically undetectable deletion.

Basic Helix-Loop-Helix Proteins↗

PubMed1997

Rare trisomy mosaicism diagnosed in amniocytes, involving an autosome other than chromosomes 13, 18, 20, and 21: karyotype/phenotype correlations.

In order to determine the significance of trisomy mosaicism of an autosome other than chromosomes 13, 18, 20, and 21, 151 such cases diagnosed prenatally through amniocentesis were reviewed. These rare trisomy mosaicism cases include 54 from 17 cytogenetic laboratories, 34 from a previous North American mosaicism survey, and 63 from published reports. All were cases of true mosaicism with information available on pregnancy outcome, and with no evidence of biased ascertainment. There were 11 cases of 46/47, +2; 2 of 46/47, +3; 2 of 46/47, +4; 5 of 46/47, +5; 3 of 46/47, +6; 8 of 46/47, +7; 14 of 46/47, +8; 25 of 46/47, +9; 2 of 46/47, +11; 23 of 46/47, +12; 5 of 46/47, +14; 11 of 46/47, +15; 21 of 46/47, +16; 7 of 46/47, +17; 1 of 46/47, +19; and 11 of 46/47, +22. As to the risk of an abnormal outcome, the data showed a very high risk (> 60 per cent) for 46/47, +2, 46/47, +16, and 46/47, +22; a high risk (40-59 per cent) for 46/47, +5, 46/47, +9, 46/47, +14, and 46/47, +15; a moderately high risk (20-39 per cent) for 46/47, +12; a moderate risk (up to 19 per cent) for 46/47, +7 and 46/47, +7 and 46/47, +8; a low risk for 46/47, +17; and an undetermined risk, due to lack of cases, for the remaining autosomal trisomy mosaics. Most cases were evaluated at birth or at termination, so subtle abnormalities may have escaped detection and developmental retardation was not evaluated at all. Comparison of the phenotypes of prenatally diagnosed abnormal cases and postnatally diagnosed cases with the same diagnosis showed considerable concordance. Since the majority of anomalies noted are prenatally detectable with ultrasound, an ultrasound examination should be performed in all prenatally diagnosed cases. In cytogenetic confirmation studies, the data showed much higher confirmation rates in cases with abnormal outcomes than in cases with normal outcomes [81 per cent vs. 55 per cent for fibroblasts (from skin, fetal tissue, and/or cord); 88 per cent vs. 46 per cent for placental cells; 22 per cent vs. 10 per cent for blood cells]. The confirmation rate reached 85 per cent when both fibroblasts and placental tissues were studied in the same case (with trisomic cells found in one or the other, or both). Therefore, one must emphasize that both fibroblasts and placental tissues should be studied. Except for 46/47, +8 and 46/47, +9, PUBS is of limited value for prenatal diagnosis of rate trisomy mosaicism. DNA studies for UPD are suggested for certain chromosomes with established imprinting effects, such as chromosomes 7, 11, 14, and 15, and perhaps for chromosomes 2 and 16, where imprinting effects are likely.

Adolescent↗

PubMed1997

Myelodysplastic syndrome presenting with clonal rearrangement isolated to chromosomal region 1q.

Myelodysplastic syndrome (MDS) is a malignant hematologic disorder that may present with clinical features consistent with the diagnosis of severe aplastic anemia (SAA). Distinguishing the two disorders may depend on the presence of a clonal chromosomal abnormality. In the following, we report a case of MDS associated with what we believe to be a previously unreported clonal abnormality of chromosome 1q, a finding that enabled us to distinguish between MDS and SAA.

Adult↗

PubMed1997

Cytogenetic studies in prostate cancer: are we making progress?

Prostate cancer is the most commonly diagnosed male malignancy in western countries. Recent work in cell biology and molecular cytogenetics has led to a large amount of data on chromosomal abnormalities in prostatic tumors. A highlight of the literature describing both classical and molecular cytogenetic studies of prostate cancer is presented. By conventional cytogenetics, predominant changes included gain of chromosome 7, loss of Y, deletions of 7q and 10q, and the appearance of double minutes. Using fluorescence in situ hybridization, predominant changes included gains of chromosomes 1, 7, 8, 8q sequences, 17, X and Y, and loss of chromosomes 1, 7, 8, 8p sequences, 10, 10q, 16q and 17q sequences, 17 and Y. Newly defined sites by comparative genomic hybridization included loss of genetic material on 2q, 5q, 6q, 9q, 13q, 15q, 17p, and 18q, and gains at 1q, 2p, 3q, 7q, 9q, 11p, 16p, 20, 22, and X. These data indicate that multiple non-random genomic sites are involved in prostate tumorigenesis. This wide and relatively recent gain of information is likely to provide key clues to the biologic basis of this disease.

Chromosome Aberrations↗

PubMed1997

Progression of metastatic human prostate cancer to androgen independence in immunodeficient SCID mice.

Prostate cancer mortality results from metastasis to bone and hormone-independent tumor growth. Models to study these progressive changes are lacking. Here we describe the propagation of advanced human prostate cancer by direct transfer of surgical samples from patients into immune-deficient male SCID mice. Explants from six of eight patients formed prostate tumors and two showed unique cytogenetic, biologic and molecular features that were retained through six or more passages. One grew in an androgen-independent fashion, whereas the second formed tumors that regressed following castration then regrew. Micrometastatic disease was detected in the hematopoietic tissues of half of the recipient mice. Thus selected specimens of advanced human prostate cancer can be propagated in SCID mice in a manner that recapitulates the clinical transition from androgen-sensitive to androgen-independent growth, accompanied by micrometastasis.

Androgens↗

PubMed1997

Allelic loss detected on chromosomes 8, 10, and 17 by fluorescence in situ hybridization using single-copy P1 probes on isolated nuclei from paraffin-embedded prostate tumors.

We have implemented a reliable new technique for preparing isolated prostate cancer nuclei from paraffin-embedded tissue sections followed by analysis with single-copy fluorescence in situ hybridization (FISH). Our initial validation is described by comparison of our data with fresh prostate tumor tissue and loss of heterozygosity (LOH) studies. We also describe evaluation of 36 previously unstudied prostate cancer patients. Fifteen archival samples were selected from patients who underwent radical prostatectomy in which direct FISH and LOH data were available. Isolated nuclei were prepared and allelic loss was detected on 17q using a single-copy DNA (P1 phage) probe by FISH. A high (80%) concordance was found when comparing isolated nuclei data with 17q results from fresh preparations and LOH studies. We also examined loss at sites on 8p, 10q, and 17q in samples from 36 patients for whom clinical information was available. Loss was found at any of the three loci in 32/36 (89%) of the specimens with specific loss in 53% of the cases at the 8p locus, 33% at the 10q locus, and 61% at the 17q locus. Studies indicate that, as well as providing potential clinical information, isolated nuclei preparations are as reliable as fresh tissue for single-copy FISH studies.

Aged↗

PubMed1997

Comparative genomic hybridization and molecular cytogenetic characterization of two prostate cancer xenografts.

Conventional cytogenetic analysis of two prostate tumor xenografts, LuCaP 23.1 and RP22090, was unsatisfactory for comprehensive genetic evaluation of the cell lines. Fluorescence in situ hybridization (FISH) for chromosome enumeration and comparative genomic hybridization (CGH) for numerical imbalance detection were performed and resulted in a more complete molecular cytogenetic characterization of these lines. Both xenografts were hypertriploid and had significant numerical imbalances. For example, LuCaP 23.1 had gain of all or part of chromosomes 3, 5, 6, 7, 8, 11, and 12 and the X chromosome and loss of all or part of chromosomes 2, 3 6, 8, 9, 10, 17, and 18. In RP22090, gain of all or part of chromosomes 5, 7, 8, 9, 10, 12, 14, and 15 was seen, whereas loss was seen for all or part of chromosomes 4, 6, 8, 15, 16, 17, 19, 20, and 22. Both xenografts reflect the high frequency of chromosomal changes seen in some late-stage prostate cancers, including many novel changes and some changes such as the loss of 8p and gain of 8q, which have been reported previously in primary and metastatic prostate cancers. Consistent changes in both lines, such as loss of chromosomes 6 and chromosome arm 8p and gain of chromosome 7 and chromosome arm 8q, may represent genetic events specific for prostate cancer development, but imbalances on other chromosomes such as 3, 9, 19, and 20, not frequently reported in prostate cancers, may reflect potentially important changes that should also be examined.

Adenocarcinoma↗

PubMed1997

Pilot studies for proficiency testing using fluorescence in situ hybridization with chromosome-specific DNA probes: a College of American Pathologists/American College of Medical Genetics Program.

Fluorescence in situ hybridization using chromosome-specific DNA probes is rapidly becoming part of clinical laboratory practice for certain congenital and neoplastic disorders. Current legislation requires proficiency testing for clinical laboratory studies. To evaluate the efficacy of fluorescence in situ hybridization proficiency testing, we invited 19 representative institutions to participate in three pilot studies. One study used probes for the X and Y chromosomes to evaluate metaphase spreads and interphase nuclei. Another study used probes for bcr and abl to detect bcr/abl fusion in interphase nuclei in chronic myelogenous leukemia. The third study used a D22S75 probe to detect microdeletions in metaphase spreads from a patient with velocardiofacial syndrome. The results of these studies demonstrate that proficiency testing with fluorescence in situ hybridization is attainable using either metaphase or interphase preparations, and that either microscope slides or fixed cell pellets are suitable.

Chromosome Mapping↗

PubMed1996

Familial ring (19) chromosome mosaicism: case report and review.

Ring (19) chromosomal mosaicism has been identified in a 14-month-old girl referred for cytogenetic evaluation due to microcephaly and developmental delay with autistic-like mannerisms. An analysis of her peripheral blood lymphocytes showed a 46,XX,r(19) cell line in 119/121 of cells examined. Of the two remaining cells, one had a normal female chromosome complement and the other showed loss of one of the chromosome 19 homologs. Further analysis by fluorescence in situ hybridization using an all human telomere probe showed the presence of a single hybridization signal on the r(19) chromosome. Subsequent cytogenetic characterization of cells derived from the patient's phenotypically normal mother also demonstrated the presence of a ring 19 chromosome in 4/100 cells. The remaining cells had a normal female chromosome complement. These findings represent the first reported case of familial ring 19 mosaicism. The cytogenetic and clinical findings in these two individuals are discussed in relation to six previously reported cases of de novo ring chromosome 19 mosaicism.

Adult↗

PubMed1996

Assignment of human protein phosphatase 2A regulatory subunit genes b56alpha, b56beta, b56gamma, b56delta, and b56epsilon (PPP2R5A-PPP2R5E), highly expressed in muscle and brain, to chromosome regions 1q41, 11q12, 3p21, 6p21.1, and 7p11.2 --> p12.

The activity of the major intracellular protein phosphatase, protein phosphatase 2A (PP2A), is determined by the nature of the associated regulatory subunit. A new family of human PP2A regulatory subunits has recently been identified. Three of these subunits, B56beta, B56delta, and B56epsilon, are most highly expressed in brain, while the B56alpha and B56gamma isoforms are highly expressed in cardiac and skeletal muscle. Genes PPP2R5A-PPP2R5E encoding the phosphatase regulatory proteins B56alpha, B56beta, B56gamma, B56delta, and B56epsilon have now been mapped by fluorescence in situ hybridization to chromosome regions 1q41, 11q12, 3p21, 6p21.1, and 7p11.2 --> p12, respectively.

Brain Chemistry↗

PubMed1996

Cytogenetic and molecular analysis in trisomy 12p.

We studied a male patient with de novo pure trisomy 12p syndrome by molecular analysis and fluorescence in situ hybridization (FISH) with markers from chromosome 12. G-banding studies demonstrated a 46,XY, 22p+ karyotype and the banding pattern and clinical findings suggested that the extra chromosomal material was derived from 12p. Trisomy 12p was confirmed by dosage analysis with chromosome 12p markers and FISH analysis with a whole chromosome 12 paint. The de novo re-arranged chromosome was of paternal origin. A comparison of the clinical and cytogenetic findings in this patient was made with previously described cases of trisomy 12p. We propose a classification system for 12p trisomy in order to better characterize the correlative relationships between specific cytogenetic constitution and phenotype.

Abnormalities, Multiple↗

PubMed1996

Suppression of the malignant phenotype of human prostate cancer cell line PPC-1 by introduction of normal fragments of human chromosome 10.

Numerous studies have detected frequent losses of heterozygosity at polymorphic loci on chromosomal arms 10p and 10q in human prostate cancers. To confirm the presence of tumor suppressor genes in these chromosomal regions, fragments of normal human chromosome 10 tagged with a neomycin resistance gene were transferred into cells from a human prostate cancer cell line. PPC-1, by microcell-mediated chromosome transfer. Two of the six hybrid clones obtained showed decreased tumorigenicity in athymic nude mice and decreased efficiency of colony formation in soft agar compared with PPC-1; the other four retained fully malignant phenotypes. Analysis of polymorphic loci on chromosome 10 in these hybrid clones suggested that a tumor suppressor gene associated with prostate cancer is located within a 17-cM region at distal 10p.

Animals↗

PubMed1996

The detection of contiguous gene deletions at the neurofibromatosis 1 locus with fluorescence in situ hybridization.

Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized primarily by the development of multiple neurofibromas and pigmentary changes. The recent identification of contiguous gene deletions in NF1, a previously unrecognized molecular basis for this disorder, raises important questions regarding deletion frequency in the patient population and the role that contiguous genes may play in the physical manifestations of NF1 patients. To facilitate the identification of patients with large NF1 deletions, we have isolated clones carrying large genomic segments from the NF1 locus and tested their efficacy as probes for fluorescence in situ hybridization (FISH). Clone P1-9 spans approximately 65 kb of the NF1 gene, including exons 2-11, and clone P1-12 carries approximately 55 kb of NF1 intron 27B. FISH studies performed with P1-9, P1-12, and a set of overlapping 1F10 cosmid clones mapping telomeric to the NF1 locus identified large deletions in two new neurofibromatosis type 1 patients who, like previously characterized deletion patients, had mildly dysmorphic facial features and large numbers of cutaneous neurofibromas.

Chromosome Aberrations↗

PubMed1996

Evidence for a tumor suppressor gene distal to BRCA1 in prostate cancer.

PURPOSE: The breast-ovarian cancer susceptibility gene, BRCA1, has been implicated by both epidemiologic and genetic studies to be involved in prostate cancer. We wished to test the frequency of BRCA1 deletion and that of other markers in the region of proximal 17q in prostate tumor cells. MATERIALS AND METHODS: We used a dual-color fluorescence in situ hybridization (FISH) assay using P1 phage probes for the BRCA1 gene and 3 flanking sites at 17q12-21, as well as a chromosome 17 centromere-specific alpha-satellite probe, to detect deletions in single-cell suspensions and touch preparations from 23 primary clinical stage B prostate tumors and adjacent nontumor prostate tissues. Lymphoblastoid cells and prostate cells from a normal donor were used to determine control loss values. RESULTS: Significant loss (p < 0.05) of at least 1 of the P1s was detected in 16 of 23 (70%) cases, and in 4 of those cases all markers were lost, consistent with whole chromosome loss. Of the 12 cases with subchromosomal loss, 8 had loss distal to BRCA1. Loss was detected in 5 cases previously reported by using allelic imbalance (AI) methodologies, and was detected in an additional 11 non-AI cases, suggesting that FISH is more sensitive than AI for deletion detection in prostate tumor cells. CONCLUSIONS: The data suggest that the region distal to BRCA1 may contain 1 or more prostate-specific tumor suppressor genes and that BRCA1 itself plays only a minor role in prostate cancer development.

BRCA1 Protein↗

PubMed1995

Suppression of malignant phenotype in a human prostate cancer cell line by fragments of normal chromosomal region 17q.

Recent evidence obtained by in situ hybridization indicates that chromosomal region 17q is often lost in prostate tumors. To substantiate the presence of tumor suppressor genes in this chromosomal region, normal human 17q tagged with a neomycin resistance gene was transferred into a human prostate cancer cell line, PPC-1, by microcell-mediated chromosome transfer. Two hybrid clones were obtained, both of which showed decreased tumorigenicity in athymic nude mice and decreased efficiency of colony formation in soft agar with respect to PPC-1. When microcells were irradiated prior to transfer of chromosomal region 17q to determine which subchromosomal regions carry the potential tumor suppressor gene(s), 10 hybrid clones were obtained, including 6 fully malignant and 4 suppressed clones. Analysis of polymorphic loci on 17q in the series of hybrid clones suggested that a tumor suppressor gene associated with prostate cancer was located in a region no more than 28 cM long at 17q12-q22, which includes the BRCA1 gene involved in hereditary breast cancer.

Animals↗

PubMed1995

Loss of chromosome 17 loci in prostate cancer detected by polymerase chain reaction quantitation of allelic markers.

Using a polymerase chain reaction/microsatellite marker system, we demonstrated that 6 of 22 (27%) clinical stage B (early) primary prostate tumors showed loss of heterozygosity at one or more of five loci on chromosome 17. The sensitivity of this study was increased by use of a PhosphorImager and statistical analysis of replicate tumor-normal DNA pairs. Two patients showed tumor-specific interstitial loss at a locus in close proximity to the familial breast cancer gene BRCA1. These findings suggest that genes on the proximal long arm of chromosome 17 play a pivotal role in the early development of at least a subset of prostatic tumors.

Alleles↗

PubMed1995

Molecular cytogenetic analysis of a t(7;10) in a human glioblastoma cell line.

Glioblastoma multiforme (GBM) is the most malignant glial brain tumor in humans. The fact that deleted copies of chromosome 10 are observed frequently in primary GBM tumors supports the hypothesis that one or more tumor suppressor genes located on chromosome 10 occupy crucial growth control checkpoints for glial cells. Deletion mapping in primary GBM tumors using the loss of heterozygosity (LOH) test has implicated the 10q24-10qter region as one possible site for a gene. We report here on the molecular cytogenetic analysis of chromosome 10 abnormalities in a human GBM cell line, JBSA. LOH testing showed that JBSA cells were hemizygous for chromosome 10. Molecular cytogenetic analysis showed that the undeleted homologue was involved in a reciprocal translocation t(7;10)(p21;q22). The translocation breakpoint on chromosome 10 lay within band q22 between D10S19 and D10S4. The fact that JBSA cells lack one homologue of chromosome 10 and carry a translocation breakpoint on the remaining one, proximal to the smallest region of overlap reported in primary tumor deletions, suggests that 10q22 may be another possible site for a tumor suppressor gene involved in GBM.

Brain Neoplasms↗