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S Joos

Publications and source records attributed to S Joos.

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

Analysis of chromosomal imbalances in sporadic and NF1-associated peripheral nerve sheath tumors by comparative genomic hybridization.

Peripheral nerve sheath tumors arise either sporadically or in association with neurofibromatosis type 1 (von Recklinghausen's neurofibromatosis, NF1) or type 2. In this study, comprehensive screening for relative chromosome copy number changes was performed on 10 benign and 19 malignant peripheral nerve sheath tumors (MPNSTs) by applying comparative genomic hybridization (CGH). In benign tumors, no chromosomal imbalances were found by CGH, whereas in MPNSTs chromosomal gains and losses were frequently detected. No differences regarding the frequency and distribution of chromosomal imbalances were observed between the 13 sporadic and 6 NF1-associated MPNSTs analyzed. In both, the number of gains was significantly higher than the number of losses, suggesting a predominant role of proto-oncogene activation during MPNST progression. Candidate regions with potentially relevant proto-oncogenes included chromosomal bands 17q24-q25, 7p11-p13, 5p15, 8q22-q24, and 12q21-q24; those with putative tumor suppressor genes were 9p21-p24, 13q14-q22, and 1p. High-level amplifications were restricted to sporadic tumors and affected eight different chromosomal subregions. In three of these MPNSTs, identical subregions on chromosomal arms 5p and 12q were coamplified. This study revealed a number of new characteristic chromosomal imbalances and provides a basis for molecular identification of oncogenes and tumor suppressor genes of pathogenetic relevance in both sporadic and NF1-associated MPNSTs. Genes Chromosomes Cancer 25:362-369, 1999.

Adolescent↗
PubMed1998

Application of interphase fluorescence in situ Hybridization for the detection of the Burkitt translocation t(8;14)(q24;q32) in B-cell lymphomas.

The translocation t(8;14)(q24;q32) is the characteristic chromosomal aberration of Burkitt's-type lymphomas and leukemias (BLs). On the molecular level, the t(8;14) juxtaposes the c-myc gene in 8q24 next to the IgH locus in 14q32, resulting in overexpression of the transcription factor c-Myc. The detection of a t(8;14) is a major aim in the diagnostic process of all patients with high-grade B-cell lymphomas because treatment strategies differ between BL and other high-grade lymphomas. As chromosome analyses are sometimes hampered by the low yield or poor quality of metaphase spreads and as the application of molecular genetic techniques is limited by the distribution of the 8q24 breakpoints over a region of about some hundred kilobases, we set out to establish an interphase fluorescence in situ hybridization (FISH) assay for the detection of the t(8;14). A cosmid probe hybridizing to the IgH constant region in 14q32 was combined with a differently labeled probe of pooled cosmid clones spanning the c-myc locus in 8q24. Interphase nuclei lacking a t(8;14) show two separated signals corresponding to each probe, whereas interphase nuclei carrying a t(8;14) display a split of the c-myc probe and a colocalization of at least one of the splitted signals with the IgH probe. Based on the results of extensive control studies, the cutoff level for this stringent (type I) criteria was set at 2%. Additionally, colocalization of at least one c-myc signal with one IgH signal alone (without signal split for the c-myc probe) was used as a less stringent (type II) criteria with a cutoff limit of 11%. Nine BLs and one Burkitt-like lymphoma were investigated by this approach. Cytogenetically, all tumors contained a translocation t(8;14)(q24;q32) except for one BL, in which cytogenetic analysis had failed. In interphase FISH, all lymphomas and leukemias met the less stringent criteria for the diagnosis of the t(8;14). Additionally, in all tumors but the Burkitt-like lymphoma, a t(8;14) could be diagnosed according to the stringent criteria. The percentage of cells found to harbor the t(8;14) by FISH ranged from 4.3% to 100%. Comparison of cytogenetic and FISH results revealed a significantly lower percentage of t(8;14)+ interphase nuclei than metaphase cells (P = .004). In conclusion, the described FISH assay provides a feasible and sensitive tool for the routine detection of the translocation t(8;14) in interphase cells which might also offer new insights into the biology of high-grade B-cell lymphomas.

Adult↗
PubMed1998

Recurrent chromosomal imbalances detected in biopsy material from oral premalignant and malignant lesions by combined tissue microdissection, universal DNA amplification, and comparative genomic hybridization.

Biopsies routinely performed for the histopathological diagnosis of oral epithelial lesions before treatment were screened for chromosomal imbalances by comparative genomic hybridization. Comparative genomic hybridization was performed on 12 oral premalignant lesions (OPLs; dysplasias and carcinomas in situ) and 14 oral squamous cell carcinomas (OSCCs). Eight biopsies displayed areas of different histopathological appearance, so that OPLs and OSCCs from the same patient were analyzed. To avoid contamination with nonneoplastic cells, defined cell populations were isolated by micromanipulation with a glass needle. Before comparative genomic hybridization analysis, universal DNA amplification was performed using the DOP-polymerase chain reaction protocol. In the 14 OSCCs examined, the average number of chromosomal imbalances was significantly higher than in the 12 OPLs (mean +/- SEM: 11.9 +/- 1.9 versus 3.2 +/- 1.2; P = 0.003). The DNA copy number changes identified in more than one OPL were gains on 8q (3 of 12) and 16p (2 of 12), as well as losses on 3p (5 of 12); 5q (4 of 12); 13q (3 of 12); and 4q, 8p, and 9p (2 of 12 each). In more than 30% of OSCCs, gains of chromosomal material were identified on 20q (8 of 14); 8q, 11q, 22q (7 of 14 each); 3q, 15q, and 17p (6 of 14 each); and 14q, 17q, and 20p (5 of 14 each), and losses were identified on 3p and 4q (9 of 14 each), 5q (7 of 14), 13q (6 of 14), and 2q and 9p (5 of 14 each). These results were validated by positive and negative control comparative genomic hybridization experiments and microsatellite analysis for the detection of allelic loss. The vast majority of genomic alterations found in OPLs were again identified in OSCCs from the same biopsy, supporting the hypothesis that multiple lesions in the same patient are clonally related. In summary, we show that comprehensive information on the genomic alterations in oral epithelial lesions can be obtained from small biopsies. Such data may identify prognostic indicators that could eventually assist in designing therapeutic strategies.

Adult↗
PubMed1998

Application of interphase cytogenetics for the detection of t(11;14)(q13;q32) in mantle cell lymphomas.

BACKGROUND: The chromosomal translocation t(11;14)(q13;q32) is the hallmark of mantle cell lymphoma (MCL) in which it can be detected cytogenetically in about 75% of cases. The t(11;14) translocation juxtaposes the bcl-1 locus in chromosome band 11q13 next to the IgH locus in chromosome band 14q32 and, thus, leads to deregulation of the cell cycle regulatory protein cyclin D1, which is encoded by the CCND1 gene localized at the telomeric border of the bcl-1-locus. MCL has the worst prognosis of all low-grade non-Hodgkin's lymphomas (NHL). In some instances, however, histopathologic differentiation between MCL and other low-grade B-cell NHL is difficult. Therefore, detection of the t(11;14) translocation is of essential diagnostic value for the risk-adjusted management of patients with MCL. Unfortunately, chromosome analyses are frequently hampered by the low yield and quality of tumor metaphases. As the 11q13 breakpoints are scattered over a region of more than 120 kb the application of molecular genetic techniques is also limited. PATIENTS AND METHODS: We established an interphase fluorescence in situ hybridization (FISH) approach for the detection of the t(11;14) translocation by use of a cosmid probe hybridizing to the IgH constant region and a YAC spanning the bcl-1 region. Cells containing a t(11;14) translocation show a colocalisation of the signals for IgH and bcl-1. Eight control samples and 15 MCL specimens were investigated. RESULTS: According to our control studies, samples containing more than 10% of cells with this signal constellation can be diagnosed as carrying a clonal t(11;14) translocation. All eleven MCL found to carry the t(11;14) translocation by chromosome analysis were positive in our FISH assay. Additionally, two of four MCL lacking a clonal t(11;14) translocation by chromosome analysis were shown to carry this aberration in 14% and 37% of interphase nuclei. Southern blot data indicate that our FISH assay reliably detects the t(11;14) translocation irrespective of the location of the breakpoints within the bcl-1 region. CONCLUSIONS: The described interphase FISH assay provides a reliable and routinely applicable tool for diagnosis of the t(11;14) translocation.

Aged↗
PubMed1998

Molecular analysis of childhood primitive neuroectodermal tumors defines markers associated with poor outcome.

PURPOSE: The diagnostic and prognostic significance of well-defined molecular markers was investigated in childhood primitive neuroectodermal tumors (PNET). MATERIALS AND METHODS: Using microsatellite analysis, Southern blot analysis, and fluorescence in situ hybridization (FISH), 30 primary tumors and six CSF metastasis specimens were analyzed for loss of heterozygosity (LOH) of chromosomes 1q31, 6q, 9q22, 10q, 11, 16q22, and 17p13.1 and/or high-level amplification of the c-myc gene. Experimental data were compared with clinical stage and outcome. RESULTS: LOH of chromosome 17p13.1 was found most frequently (14 of 30 tumors, six of six CSF metastasis specimens); LOH of chromosomes 10q, 16q22, 11, 6, 9q22, and 1q31 was observed in 20.6%, 20%, 14.3%, 12%, 10%, and 0%, respectively. Eight of 32 tumors and CSF specimens showed amplification of c-myc. All tumors with amplification of c-myc were resistant to therapy and had a fatal outcome (mean survival time, 9.3 months). Tumors that displayed LOH of chromosome 17p were associated with metastatic disease. The prognosis of these tumors was worse only when associated with amplification of c-myc. Three of three patients with LOH of 9q22 relapsed. CONCLUSION: In our study, amplification of c-myc was a poor-prognosis marker in PNET. LOH of chromosome 17p was associated with metastatic disease. Molecular analysis of primary tumors using these markers may be useful for stratification of children with PNET in future prospective studies. The other aberrations investigated were not of significant prognostic value, but may provide an entry point for future large-scale molecular studies.

Adolescent↗
PubMed1998

[Analysis of chromosome copy number changes in leiomyosarcoma through molecular cytogenetic methods].

Leiomyosarcoma (LMS) is a rare type of malignant soft tissue tumor occurring predominantly in adults. Up to now only few zytogenetic data resulting from chromosomal banding analyses were obtained from this tumor type. In general, highly complex karyotypes were observed, but no recurrent chromosomal aberrations could be identified. The aim of the present study was to analyze chromosomal imbalances in 14 cases of LMS using comparative genomic hybridization (CGH). Imbalances were detected in all cases analyzed, with chromosomal gains occurring more frequently than losses (9.9 gains/case vs. 6.9 losses/case, respectively). Chromosome arms predominantly overrepresented included Xp (9/14 cases), 5p and 8q (8/14 each), as well as 17p and 17q (6/14 each). Nineteen distinct high level amplifications, indicative for the location of relevant proto-oncogenes in LMS, were identified in nine different tumors. Interestingly, in three cases chromosomal arm 17p was involved. Interphase analysis with probes derived from the commonly amplified region 17p11-p12 revealed, that the tre oncogene is co-amplified and therefore could play a relevant role in LMS development. With regard to losses chromosome 13q was affected in 12/14, 10q in 8/14, and 2p as well as 2q in 7/14 tumors, respectively. The frequent deletions of chromosome 13 with a minimal affected region 13q14-q15 strongly support preliminary molecular evidence, that loss of the RB1 tumor suppressor gene is a critical step in LMS tumorigenesis.

Adult↗
PubMed1997

High-level DNA amplifications are common genetic aberrations in B-cell neoplasms.

Gene amplification is one of the molecular mechanisms resulting in the up-regulation of gene expression. In non-Hodgkin's lymphomas, such gene amplifications have been identified rarely. Using comparative genomic hybridization, a technique that has proven to be very sensitive for the detection of high-level DNA amplifications, we analyzed 108 cases of B-cell neoplasms (42 chronic B-cell leukemias, 5 mantle cell lymphomas, and 61 aggressive B-cell lymphomas). Twenty-four high-level amplifications were identified in 13% of the patients and mapped to 15 different genomic regions. Regions most frequently amplified were bands Xq26-28, 2p23-24, and 2p14-16 as well as 18q21 (three times each). Amplification of several proto-oncogenes and a cell cycle control gene (N-MYC (two cases), BCL2, CCND2, and GLI) located within the amplified regions was demonstrated by Southern blot analysis or fluorescence in situ hybridization to interphase nuclei of tumor cells. These data demonstrate that gene amplifications in B-cell neoplasms are much more frequent than previously assumed. The identification of highly amplified DNA regions and genes included in the amplicons provides important information for further analyses of genetic events involved in lymphomagenesis.

Cell Cycle Proteins↗
PubMed1996

High incidence of chromosomal imbalances and gene amplifications in the classical follicular variant of follicle center lymphoma.

The classical follicular variant of follicle center lymphoma (FCL-fo) is associated with the chromosomal translocation t(14;18)(q32;q21). However, the sole presence of this translocation is not sufficient for malignant transformation, as demonstrated by experiments in a transgenic mouse model. Most of the secondary changes, which play a central role in tumor development and progression and which are presumed to be of prognostic value, are gains and losses of chromosomal material. We analyzed 28 FCL-fo patients using comparative genomic hybridization (CGH). The most frequent imbalances were gains on chromosomes X, 7, 8, 12, and 18 as well as losses of material on chromosome arm 6q. For chromosomes X, 8, 12, and 18, the CGH data allowed further narrowing of the relevant subregions. In addition, novel high-level DNA amplifications were identified in five instances mapping to chromosome bands 1p36, 6p21, 8q24 (2 patients), and 12q13-14. Previously, such amplifications have been identified very rarely in lymphomas. In the 2 patients with amplifications mapping to chromosomal band 8q24, involvement of the MYC proto-oncogene in the amplification unit was demonstrated by Southern blot analysis. These data provide further entry points for studies to identify genes relevant for tumor progression in FCL-fo.

Adult↗
PubMed1996

Primary mediastinal (thymic) B-cell lymphoma is characterized by gains of chromosomal material including 9p and amplification of the REL gene.

Primary mediastinal (thymic) B-cell lymphoma is a high-grade non-Hodgkin's lymphoma with unique features. By using comparative genomic hybridization and interphase cytogenetics, 26 tumors were analyzed to identify genomic imbalances. Gains of chromosomal material were much more frequent than losses (110 v 10) and involved chromosomes 9p, 12q, and Xq (31% to 50%). Interestingly, gain of Xq coincided with gain of 9p. Distinct high-level amplifications were found in four subregions. In 2 cases, amplifications of proto-oncogene REL were shown by filter hybridization, indicating a possible pathogenic role of this gene. The characteristic pattern of chromosomal imbalances distinct from other B-cell lymphomas suggests a specific pathway of genetic changes associated with this lymphoma.

Aneuploidy↗
PubMed1996

Mapping of chromosomal gains and losses in primitive neuroectodermal tumors by comparative genomic hybridization.

A series of 18 primitive neuroectodermal tumors (PNETs), the most common malignant central nervous system tumors of childhood, were analyzed with the recently developed approach of comparative genomic hybridization (CGH). In five cases, in which only small amounts of DNA were available, universal polymerase chain reaction was successfully applied to generate adequate probe material. In 15 tumors, chromosomal imbalances were elicited, most frequently involving chromosome 17 (loss of 17p and gain of 17q). Further recurrent imbalances included gains of the distal regions of 4p, 5p, 5q, 7q, 8q, and 9p. High-level amplifications were found on 2p24 (one case) and 8q24 (three cases), suggesting involvement of the protooncogenes MYCN and MYC, respectively. In one of these cases, Southern blot analysis could be performed, proving high-copy-number amplification of MYC. Interestingly, none of the three patients with high-copy-number amplifications of MYC responded to therapy.

Adolescent↗
PubMed1996

Early detachment of colon carcinoma cells during CD95(APO-1/Fas)-mediated apoptosis. I. De-adhesion from hyaluronate by shedding of CD44.

Ligation of CD95 (APO-1/Fas) cell surface receptors induces death in apoptosis-sensitive cells. Induction of apoptosis in adherent gamma interferon-stimulated HT-29 and COLO 205 colon carcinoma cells by cross-linking CD95 with anti-APO-1 monoclonal antibody resulted in detachment of the cells from hyaluronate starting about 1 h after antibody exposure. Loss of adhesion was paralleled by a substantial reduction of the multifunctional cell surface adhesion molecule CD44. As evidenced by cycloheximide treatment, this effect was not caused by impaired protein synthesis. Depletion of surface CD44 was also not due to membrane blebbing, since cytochalasin B failed to inhibit ascension from hyaluronate. Instead, ELISA and time kinetics showed increasing amounts of soluble CD44 in the supernatant of CD95-triggered cells. SDS-PAGE revealed that soluble CD44 had an apparent molecular mass of about 20 kD less than CD44 immunoprecipitated from intact cells. Thus, CD95-triggering induced shedding of CD44. Shedding is a novel mechanism operative in early steps of CD95-mediated apoptosis. Shedding surface molecules like CD44 might contribute to the active disintegration of dying epithelial cells in vivo.

Apoptosis↗
PubMed1996

Chromosome imbalances in papillary renal cell carcinoma and first cytogenetic data of familial cases analyzed by comparative genomic hybridization.

We used comparative genomic hybridization to analyze 17 tumor samples from 11 patients with papillary renal cell carcinoma (RCC), including three patients with hereditary papillary RCC. Whereas the most frequent aberrations confirmed data obtained by banding analyses, copy number increases on 5q, which previously were considered characteristic of nonpapillary RCC, were identified in two cases. In two complex cases belonging to the same family, a characteristic pattern of chromosomal aberrations was found: five of the six imbalances present in the less complex case were included in the karyotype of the other case, suggesting a genetically determined mechanism resulting in genomic instability of specific chromosomes or chromosomal subregions and/or selection of specific mutations.

Adult↗
PubMed1996

Efficacy of current molecular cytogenetic protocols for the diagnosis of chromosome aberrations in tumor specimens.

Molecular cytogenetics provides a powerful link between molecular genetic analysis and chromosome morphology, allowing one to pinpoint structurally aberrant chromosome regions on the molecular level. Fluorescence in situ hybridization with selected DNA probes allows the design of efficient and sensitive tools for the diagnosis of chromosomal aberrations present in tumor cells. Comparative genomic hybridization (CGH) allows the identification of chromosomal imbalances in a comprehensive manner, and is applied to solid tumors and hematological malignancies in order to (i) identify clonal differences within a specimen, (ii) contribute to tumor classifications, (iii) identify recurrent chromosomal gains and losses as starting points for the characterization and isolation of pathogenetically relevant genes, such as proto-oncogenes and tumor suppressor genes respectively, (iv) identify imbalances of prognostic relevance, (v) detect high-copy-number amplification and other markers of genetic instability, and (vi) analyze chromosomal imbalances during tumor progression.

Chromosome Aberrations↗
PubMed1995

Comparative genomic hybridization in chronic B-cell leukemias shows a high incidence of chromosomal gains and losses.

In chronic B-cell leukemias, fluorescence in situ hybridization has greatly improved the ability to detect certain chromosomal aberrations, as cells in all phases of the cell cycle are analyzed. To obtain a comprehensive view of chromosomal gains and losses, we applied the recently developed technique of comparative genomic hybridization (CGH) to 28 patients with chronic B-cell leukemias. CGH results were compared with those obtained by chromosome banding analysis and interphase cytogenetics. In 19 of the 28 cases, chromosomal imbalances were detected, including amplified DNA sequences in three instances. The most common aberrations included gains of chromosomal material on 8q and 12 as well as losses of 6q, 11q, 13q, and 17p. In 13 cases, CGH revealed chromosomal gains and losses not detected by banding analysis. In 8 of these 13 cases, discrepancies were further investigated using other methods, and in all instances, the CGH findings were confirmed. A limitation of detecting small deleted regions by CGH was found in one example of 18p. In conclusion, our data show that the results of banding analysis in chronic B-cell leukemias often do not reflect the chromosomal changes in the predominant cell clone. This may be one explanation for the as yet poor correlation between cytogenetic findings and clinical course in this group of neoplasms.

Chromosome Aberrations↗