DNA methylation studies on imprinted loci in a male monozygotic twin pair discordant for Beckwith-Wiedemann syndrome.

Beckwith­Wiedemann syndrome (BWS) is one of the most prevalent congenital disorders predominantly caused by epigenetic alterations. Here we present an extensive case study of a monozygotic monochorionic male twin pair discordant for BWS. Our analysis allows to correlate BWS symptoms, like a protruding tongue, indented ears and transient neonatal hypoglycaemia, to an abnormal methylation at the KvDMR1. DNAs extracted from peripheral blood, skin fibroblasts, saliva and buccal swab of both twins, their sister and parents were analysed at 11 differentially methylated regions (DMRs) including all four relevant DMRs of the BWS region. The KvDMR1 was exclusively found to be hypomethylated in all cell types of the affected BWS twin, while the unaffected twin and the relatives showed normal methylation in fibroblasts, buccal swab and saliva DNA. Interestingly, the twins share a common blood-specific hypomethylation phenotype most probably caused by a feto-fetal transfusion between both twins. Because microsatellite analysis furthermore revealed a normal biparental karyotype for chromosome 11, our results point to an exclusive correlation of the observed BWS symptoms to locally restricted epimutations at the KvDMR1 of the maternal chromosome.

Genotypic characterization of prostatic carcinomas: a combined cytogenetic, flow cytometry, and in situ DNA hybridization study.

Cytogenetic studies were performed on 36 biopsies obtained from 26 primary prostatic adenocarcinomas. Following histopathological characterization of control sections, the biopsies were investigated using metaphase cytogenetics, DNA flow cytometry, and fluorescence in situ DNA hybridization. In 12 specimens, no carcinoma was found in control sections by histopathological means. In 24 carcinoma biopsies clonal aberrations were detected in 15 specimens. Tetraploidy as sole aberration was detected in five specimens. Loss of the Y chromosome was seen in eight samples. Only one tumor revealed structural abnormalities. Eight samples were found to be normal (46,XY). Remarkably, nonclonal chromosome aberrations, particularly marked chromosome loss, were frequently detected in prostatic carcinomas and premalignant lesions (prostatic intraepithelial neoplasia). In the series of biopsies investigated by means of cytogenetics and flow cytometry, biopsies with aneuploid DNA content were found to be cytogenetically normal. Conversely, the cytogenetically aberrant clones were found to be of diploid DNA content. Evidence of focal intratumoral heterogeneity was revealed by cytogenetics, flow cytometry, and in situ hybridization.

Deletion of chromosome 1p and loss of expression of alkaline phosphatase indicate progression of meningiomas.

Meningiomas are cytogenetically characterized by loss of one chromosome 22 as a typical primary aberration and progression-associated secondary chromosome changes, of which monosomy 1p is the most common. The aim of this study was to evaluate the significance of monosomy 1p and enzyme activity loss of tissue nonspecific alkaline phosphatase (ALPL), whose gene maps to chromosome 1p36.1-p34, as parameters for the diagnosis of progression-prone meningiomas. We analyzed smear preparations of 56 meningiomas and additional paraffin sections of 17 of the cases by two-color fluorescence in situ hybridization (FISH) using the D1Z1 and D1Z2 probes and by a metaphase cytogenetic analysis of 30 of these tumors. The results were compared to clinical and morphological parameters and the expression of ALPL. Smear preparations showed deletion of 1p36 in 27% of common-type, 70% of atypical (intermediate-type), and 100% of anaplastic meningiomas. Monosomy 1p, as detected by FISH or the karyotype, was strongly associated with complete loss of ALPL activity. Intermediate-type and anaplastic meningiomas of younger patients displayed an increasing rate of cells with trisomy 1q and relative loss of 1p. The highly significant correlation of FISH results and ALPL histochemistry with clinical parameters gives evidence of their strong prognostic relevance. The complete activity loss of ALPL and the immunologically detected loss of ALPL protein in areas of meningiomas with monosomy 1p indicate a cytogenetically undetectable inactivation of the homologous Alpl allele. The apparently homozygous loss of expression of ALPL supports the notion that Alpl is a candidate tumor suppressor gene in meningiomas.

Loss of alkaline phosphatase activity in meningiomas: a rapid histochemical technique indicating progression-associated deletion of a putative tumor suppressor gene on the distal part of the short arm of chromosome 1.

Apart from defined histomorphologic features, increased Ki-67 indices and various numeric and structural chromosome aberrations, meningiomas of the intermediate (WHO grade II, atypical meningioma) and anaplastic type (WHO grade III) are cytogenetically distinguished from common-type meningiomas (WHO grade I) by frequent loss of the distal part of the short arm of one chromosome 1 (1p-), which formerly proved to be an independent predictor of shorter recurrence-free intervals. Histochemically, loss of alkaline phosphatase activity (ALPL, liver/bone/kidney type, EC 3.1.3.1) was another frequent, specific finding in meningiomas with signs of dedifferentiation. In a prospective study including 66 meningiomas, all common-type meningiomas except one case (18/19) were reactive for ALPL, whereas 75% (30/39) of intermediate type and all anaplastic meningiomas (8/8) showed loss of enzyme activity in large areas of the tumor. Exclusively, the ALPL negative phenotype was associated with 1p loss (15/19). Our data suggest that ALPL, which is coded as a single copy gene on chromosome 1p36.1-p34, is a useful marker enzyme for the loss of a putative regulatory (tumor suppressor) gene on chromosome 1p, or that ALPL itself represents a new tumor suppressor gene homozygously inactivated in meningiomas.

Evidence of focal genetic microheterogeneity in glioblastoma multiforme by area-specific CGH on microdissected tumor cells.

The term "multiforme" in glioblastoma multiforme (GBM) indicates the highly variable histomorphology that cannot be addressed by studies on homogenized tissue probes. In order to relate genetic findings with histomorphologically distinct areas we used microdissection to procure defined cell populations from microscopic tissue sections under direct visualization. Formalin-fixed and paraffin-embedded tissue sections of 10 GBM were evaluated for intratumoral genetic heterogeneity by microdissection of multiple areas of 20-50 tumor cells and DOP-PCR of DNA isolated from the dissected cell groups, followed by comparative genomic hybridization (CGH). Microdissected cells from histomorphologically normal extratumoral blood vessels from the same slides served as controls. The individual tumors showed variable combinations of primary chromosomal gains and losses common to all studied areas of a given case along with secondary, area-specific additional aberrations. CGH displayed a wider variety of chromosomal aberrations than metaphase cytogenetics of cell cultures from the same tumors. The most frequent aberrations observed were previously unperceived gains on chromosomes 4q (8/10) and 5q (5/10). Other nonrandom aberrations were gains on 12q (6/10), 13q (6/10), and 7 (5/10), and losses of 22 (5/10). Amplifications on 7p were intratumorally heterogeneous and only found in single areas of 2 tumors. In contrast to normal extratumoral vessels, vascular proliferates in most cases demonstrated chromosomal aberrations (CGH) which were partially different from the aberrations observed in the tumor itself. The described method gives evidence of considerable intratumoral genetic heterogeneity in GBM and provides a sensitive tool for the detection of quantitative chromosomal changes that are present only regionally within a given tumor.

Influence of hyperthermia on the phosphorylation of ribosomal protein S6 from human skin fibroblasts and meningioma cells.

Skin fibroblasts and meningioma cells, derived from primary cultures of the same patients have been used to study the influence of hyperthermia on (i) cell morphology and (ii) phosphorylation pattern of ribosomal and ribosome-associated proteins. Incubation of tumour cells and fibroblasts up to 7 h at 42 degrees C did not significantly change the cell morphology as compared to control cells kept at 37 degrees C. At 42 degrees C ribosomal protein S6 is shifted cathodically indicating a loss of negative charge, however no quantitative dephosphorylation of S6 was observed. Meningioma cells and fibroblasts did not differ significantly with respect to S6 phosphorylation.

Amplified met gene linked to double minutes in human glioblastoma.

The met proto-oncogene was found to be amplified in a human glioblastoma cell line (T3095) established from a glioblastoma multiform WHO grade IV. Amplification of epidermal growth factor receptor, transforming growth factor alpha and N-myc which have been described previously in glioblastoma were not observed in T3095. There was, however, an 8-fold met amplification. Giemsa-stained metaphases of T3095 cells revealed multiple (> 5) double minutes (dmins) in the majority of cells. Following xenografting in nude mice there was a significant increase in the number and frequency of dmins. The increase in dmins correlates with the level of met amplification (50-fold), suggesting localisation of the amplified met on dmins. Here we report the first case of met amplification in glioblastoma. Correlation between met amplification and extrachromosomal elements (dmins) has not been reported previously.

DNA amplifications on chromosomes 7, 9 and 12 in glioblastoma detected by reverse chromosome painting.

Biopsies and cell culture, respectively, of four human glioblastoma multiforme (WHO 4) have been evaluated for gene amplification using reverse chromosome painting. Three of the tumours showed amplified domains within chromosome bands 12q13-15. The exact localisation and extension of the amplified domains, however, varies within this region. Southern blot analysis revealed amplification of the GLI oncogene in two of the glioblastomas which were found to contain amplified domains within 12q13-15. Reverse chromosome painting also identified amplified domains within bands 7q21 and 9p23-24. Amplification within region 9p23-24 has previously not been reported in glioblastoma. The amplified domain encompassing 9p23-24 was detected in the same glioblastoma which contained an amplification unit within bands 12q13-14. These data, together with previous reports, indicate that amplifications are predominantly found on chromosomes 7, 9 and 12 in glioblastoma. In addition, this study provides further evidence that coamplification is not a rare event in glioblastoma.

Human KRAS oncogene expression in meningioma.

Expression of 16 oncogenes was investigated in a series of human meningiomas showing a normal chromosome complement or the characteristic monosomy 22 but no structural aberrations detectable by banding analysis. By dot hybridization, the only expressed sequence detected was KRAS. The expression was elevated approximately 6--8-fold in comparison to matrix tissue (meninges) and to fibroblasts of the corresponding patient. Northern blot analysis displayed the typical banding pattern and an 8--10-fold overexpression. DNA analysis did not reveal gene amplification or major rearrangements in the KRAS gene structure.

The cellular myb oncogene is amplified, rearranged and activated in human glioblastoma cell lines.

The human c-myb gene which encodes a DNA binding protein and which is rarely amplified in neoplastic cells was found to be altered in four human glioblastoma cell lines. It exists in multiple copies in 2 out of 4 cases studied. The degree of amplification as determined by densitometry was about 10-fold, a rearrangement within the coding region and an enhanced gene activity of c-myb were noted. The observation of c-myb oncogene amplification and activity in glioblastoma cell lines presents the first report of this effect in human brain tumor cells.

Infant with del(3) (p25-pter): karyotype-phenotype correlation and review of previously reported cases.

We describe a boy with monosomy for the distal part of the short arm of chromosome 3. He had a congenital heart defect, tetramelic hexadactyly, and typical craniofacial anomalies. Comparison with previously reported cases confirms that the phenotype consists of an identifiable pattern of malformation.

Pericentric inversion of chromosome 6 in a patient with cleidocranial dysplasia.

We describe a male patient with a pericentric inversion of chromosome 6 and classic cleidocranial dysplasia (CCD), mild to moderate mental retardation, hearing deficiency, and unusual facial appearance. We conclude that there is a causal relationship between the chromosomal disorder and the CCD.

Distal 2q duplication: report of two familial cases and an attempt to define a syndrome.

Two cases of partial trisomy 2q are described, both resulting from a balanced translocation in one of the parents. In one case the chromosomes 2 and 11 were involved [paternal karyotype: 46,XY,t(2;11)(q33;q23)]; in the second case, chromosomes 2 and 8 [paternal karyotype: 46,XY, t(2;8(q32;p23)]. When the two patients were compared to the few cases reported in the literature, it was concluded that the associated clinical syndrome is characterized by severe psychomotor retardation and relatively mild abnormalities involving skull and facies.

DNA aneuploidy in prostatic adenocarcinoma: a frequent event as shown by fluorescence in situ DNA hybridization.

Fluorescence in situ hybridization (FISH) using specific DNA probes for chromosomes 1, 7, 10, and Y was performed on 53 prostatic tissue samples obtained from 33 radical prostatectomy specimens and two benign control specimens. The 53 samples from carcinomatous prostates included 33 cancerous and 20 noncancerous samples. Additionally, four metastatic lymph node specimens were examined. Clonal chromosome abnormalities were observed in 78% of the tumors studied. They were detected in a higher proportion in stage pT2 and pT3 tumors (86% and 88%, respectively) compared with stage pT1 tumors (25%). No stage pT4 tumor was analyzed. There was evidence of remarkable focal intratumoral heterogeneity documented by the study of two samples from the same tumor in three of six cases. Comparing FISH determined ploidy patterns with DNA flow cytometry (FCM) in 22 samples, FISH showed aneuploidy whereas FCM showed none.

Increased amount of a mitochondria-associated 21 x 10(3) dalton protein in human gastrointestinal tumors.

Differences in the structure and number of mitochondria in tumor cells were found. Using isoelectrofocusing two-dimensional polyacrylamide gel electrophoresis which allows detection of alterations in the protein pattern of tumor mitochondria, we studied both quantitative and qualitative changes in the mitochondrial protein pattern of human gastrointestinal tumors and corresponding normal matrix tissues. One low molecular protein spot was found to be quantitatively changed in the tumors. The approximate molecular weight was 21 x 10(3) daltons and the pI value 5.7.

Karyotypic variations in human meningioma cell cultures under different in vitro conditions.

Examined were how changes of the culture medium, cultivating procedure and cultivating time will influence numerical representation of different karyotypes in a total of 27 cell cultures of meningiomas with two or more cytogenetically distinguishable cell lines. It could be shown that in medium I (80% Mc Coy 5 A, 20% fetal calf serum) more cell lines with a higher degree of hypodipoidy occurred than in medium II (50% TC 199, 40% bovine amniotic fluid, 10% calf serum). The number of cells with normal karyotype was higher in cultures which were grown from trypsinized biopsy material in stationary flasks when compared to particle cultures in roller tubes. Cells with a normal karyotype also increased after 1--6 subcultures. By demonstration of SV 40 tumor antigen it could be shown in two cultures that these normal mitoses derived from tumoral and not from stromal tissue.

Cytogenetic studies on the nucleolar organizer region [NOR] activity in meningioma cells with normal and hypodiploid karyotypes.

The association pattern and NOR silver staining of the acrocentric chromosomes was studied in normal and hypodiploid cell lines of four meningioma patients. In three cases the hypodiploid cells showed a more increased association frequency or NOR silver staining or both than the normal ones, indicating a compensatory mechanism between the NORs. Chromosomes #14 seemed to be more frequently involved in this phenomenon than other acrocentric chromosomes. From the silver staining results it was concluded that in meningioma cells, chromosomes #22 which bear active as well as inactive NORs were missing. The compensation between the NORs was probably only activated if an active NOR was lost.

Comparative genomic hybridization reveals recurrent enhancements on chromosome 20 and in one case combined amplification sites on 15q24q26 and 20p11p12 in glioblastomas.

We examined homogenized tissue samples of biopsies from 19 astrocytomas of different grades for genetic imbalances using comparative genomic hybridization (CGH): three astrocytomas grade II, and 16 astrocytomas grade IV (glioblastoma multiforme), one of the glioblastomas representing the recurrence of a benign oligoastrocytoma. In two of three cases of astrocytoma grade II, a gain of chromosome 7 was found. The alterations in the glioblastomas were complex, and most frequently showed the characteristic gain of chromosome 7 and loss of chromosome 10. The single analyzed case of recurrence of an oligoastrocytoma was characterized by a unique CGH pattern. This tumor showed two distinct alterations: apart from an amplification on 15q24q26, we found a distinct amplification of a small region on 20p11.2p12, which has not been previously described in brain tumors. Partial or complete gains of chromosome 20 arose in six other tumors; we conclude that chromosome 20 in particular 20p11. 2p12, may harbor relevant genes for glioma progression.

Establishment and characterization of a human glioblastoma cell line with a stable karyotype and nullisomy 13.

A permanent cell line (HeRo) with a stable karyotype (80-84,XXYY) and with defined numerical and structural chromosome aberrations was established from a human glioblastoma, a highly malignant brain tumor. Transformation of these cells with SV40 led to a second permanent cell line (HeRo-SV) with a reduced, but also stable, karyotype (72-74,XXYY). The morphological appearance of the glioblastoma line was similar to the main component of the original tumor tissue. The transformed cells differed from their counterparts in accelerated growth, enhanced growth in soft agar, reduced growth conditions, expression of SV40 T antigen, and altered epitheloid morphology. Both cell lines have been grown in continuous culture for more than 2 years. The stability of both the biologic properties and the karyotypic changes induced by SV40 is quite remarkable. Both lines show a nullisomy 13.

Enhanced expression of four cellular oncogenes in a human glioblastoma cell line.

Examination of a human glioblastoma cell line displaying a relatively stable karyotype and absence of both copies of chromosome #13 (HeRo) as well as of a SV-40 transformed subline (HeRo-SV) using analysis on the DNA and RNA level showed that both cell lines express high levels of abl, erb B, myc, and Ha-ras mRNA. Neither gene amplification nor gene rearrangement at the loci concerned nor abnormal transcription account for this activation of expression. The possible influence of the deleted sequences in the context of a suppressor gene hypothesis is discussed.