Biomedical subjects

R G Weber

Publications and source records attributed to R G Weber.

At least 19 recordsLinked to original sources

PubMed2006

Frequent loss of chromosome 9, homozygous CDKN2A/p14(ARF)/CDKN2B deletion and low TSC1 mRNA expression in pleomorphic xanthoastrocytomas.

The molecular pathogenesis of pleomorphic xanthoastrocytoma (PXA), a rare astrocytic brain tumor with a relatively favorable prognosis, is still poorly understood. We characterized 50 PXAs by comparative genomic hybridization (CGH) and found the most common imbalance to be loss on chromosome 9 in 50% of tumors. Other recurrent losses affected chromosomes 17 (10%), 8, 18, 22 (4% each). Recurrent gains were identified on chromosomes X (16%), 7, 9q, 20 (8% each), 4, 5, 19 (4% each). Two tumors demonstrated amplifications mapping to 2p23-p25, 4p15, 12q13, 12q21, 21q21 and 21q22. Analysis of 10 PXAs with available high molecular weight DNA by high-resolution array-based CGH indicated homozygous 9p21.3 deletions involving the CDKN2A/p14(ARF)/CDKN2B loci in six tumors (60%). Interphase fluorescence in situ hybridization to tissue sections confirmed the presence of tumor cells with homozygous 9p21.3 deletions. Mutational analysis of candidate genes on 9q, PTCH and TSC1, revealed no mutations in PXAs with 9q loss and no evidence of TSC1 promoter methylation. However, PXAs consistently showed low TSC1 transcript levels. Taken together, our study identifies loss of chromosome 9 as the most common chromosomal imbalance in PXAs and suggests important roles for homozygous CDKN2A/p14(ARF)/CDKN2B deletion as well as low TSC1 mRNA expression in these tumors.

Adolescent↗

PubMed2006

Comprehensive genomic analysis of desmoplastic medulloblastomas: identification of novel amplified genes and separate evaluation of the different histological components.

Desmoplastic medulloblastoma (DMB) is a malignant cerebellar tumour composed of two distinct tissue components, pale islands and desmoplastic areas. Previous studies revealed mutations in genes encoding members of the sonic hedgehog pathway, including PTCH, SMOH and SUFUH in DMBs. However, little is known about other genomic aberrations. We performed comparative genomic hybridization (CGH) analysis of 22 sporadic DMBs and identified chromosomal imbalances in 20 tumours (91%; mean, 4.9 imbalances/tumour). Recurrent chromosomal gains were found on chromosomes 3, 9 (six tumours each), 20, 22 (five tumours each), 2, 6, 7, 17 (four tumours each) and 1 (three tumours). Recurrent losses involved chromosomes X (eight tumours), Y (six of eleven tumours from male patients), 9, 12 (four tumours each), as well as 10, 13 and 17 (three tumours each). Four tumours demonstrated high-level amplifications involving sequences from 1p22, 5p15, 9p, 12p13, 13q33-q34 and 17q22-q24, respectively. Further analysis of the 9p and 17q22-q24 amplicons by array-based CGH (matrix-CGH) and candidate gene analyses revealed amplification of JMJD2C at 9p24 in one DMB and amplification of RPS6KB1, APPBP2, PPM1D and BCAS3 from 17q23 in three DMBs. Among the 17q23 genes, RPS6KB1 showed markedly elevated transcript levels as compared to normal cerebellum in five of six DMBs and four of five classic medulloblastomas investigated. Finally, CGH analysis of microdissected pale islands and desmoplastic areas showed common chromosomal imbalances in five of six informative tumours. In summary, we have identified several novel genetic alterations in DMBs and provide genetic evidence for a monoclonal origin of their different tissue components.

Base Sequence↗

PubMed2006

Global brain dysmyelination with above-average verbal skills in 18q- syndrome with a 17 Mb terminal deletion.

BACKGROUND: Patients with the karyotypic finding of a terminal deletion in the long arm of chromosome 18 (18q- syndrome) commonly display cerebral dysmyelination and developmental delay. To our knowledge, all reported cases characterized by molecular analysis who had no mental retardation as confirmed by neuropsychological testing had a chromosomal breakpoint within the two most distal bands, 18q22 or 18q23, leading to a deletion of 16 Mb or less. AIMS OF THE STUDY: It was the aim of this study to improve the karyotype-phenotype correlation in 18q- syndrome by thoroughly analyzing the deletion size and the mental and radiologic status in a 23-year-old woman with a terminal 18q deletion. We performed cytogenetic and molecular cytogenetic analysis, brain MRI, and extended neuropsychological testing. RESULTS: Molecular karyotyping revealed a 17 Mb deletion of terminal 18q with a breakpoint in 18q21.33 and no evidence for mosaicism. While brain MRI demonstrated severe global dysmyelination, the patient showed a neuropsychological pattern that allowed for normal psychosocial and job achievement. After delayed development in childhood, the patient caught up during puberty and showed normal verbal intelligence and skills at 23 years. However, visual, visual-spatial, visual-constructional, and executive functions were found to be severely impaired. CONCLUSION: Here, we present a patient with one of the largest terminal 18q deletions reported in an individual without obvious mental retardation. Our analysis extends the phenotypic spectrum for individuals with breakpoints in 18q21.33. In addition, this study highlights the fact that severe global dysmyelination may not be associated with general cognitive deficits.

Adult↗

PubMed2001

Analysis of human meningiomas for aberrations of the MADH2, MADH4, APM-1 and DCC tumor suppressor genes on the long arm of chromosome 18.

We have previously reported that losses of genomic material from the long arm of chromosome 18 are frequent in atypical and anaplastic meningiomas but rare in benign meningiomas. In the present study, we have investigated a series of 37 meningiomas for mutation and expression of 4 tumor suppressor genes (MADH2, MADH4, APM-1 and DCC) located at 18q21. Comparative genomic hybridization or loss of heterozygosity analysis showed losses on chromosome 18 that included sequences from 18q21 in 15 of 37 tumors. Mutation analysis of APM-1 revealed a missense mutation (c. 1819G>A: G607S) in 1 atypical meningioma. None of the tumors showed mutations of MADH2 and MADH4 or loss of detectable transcripts from MADH2, MADH4, APM-1 and DCC. In contrast to human brain tissue, normal leptomeninges and meningiomas showed preferential expression of a DCC splice variant lacking 60 base pairs from exon 17. Taken together, our data do not support a significant role for MADH2, MADH4, APM-1 and DCC alterations in the pathogenesis of meningiomas. The targeted gene that is inactivated in most meningiomas with 18q losses remains to be identified.

Adiponectin↗

PubMed2001

Chromosomal imbalances associated with response to chemotherapy and cytotoxic cytokines in human malignant glioma cell lines.

The median survival for human malignant glioma patients treated with neurosurgery and postoperative radiotherapy does not exceed one year. Only a minority of patients benefit from adjuvant chemotherapy. It was the aim of our study to determine which genomic alterations in malignant gliomas modulate the sensitivity to chemotherapy or cytotoxic cytokines such as CD95 ligand (CD95L) or Apo2L/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL). Therefore, we analyzed 12 human malignant glioma cell lines for chromosomal gains and losses by comparative genomic hybridization (CGH). The gains most commonly identified were on chromosomes 7q, 19, 1, and 20q, whereas the most frequent losses were on 13q, 11q, 18q, and 4q. By comparison with previously published data on this panel of glioma cell lines1112, we defined candidate regions which may carry genes responsible for sensitivity to chemotherapy or cytotoxic cytokines. All but one of the chromosomal regions associated with response to chemotherapy, i.e. 1p12, 3p21, 11p11.2-p13, 12q23, 17p11. 2-p13, were different from those associated with response to cytotoxic cytokines, i.e. lp12, 1q22, 12q12-q21. Genomic regions known to harbor major candidate genes, including genes encoding death ligands, death receptors, caspases and BCL-2 family proteins, were not found to be imbalanced. In addition, we identified 5q13-q14, 5q34, 10p11.2, 9q21-q34 as genomic regions associated with the proliferative activity of malignant glioma cell lines. Cell lines with gain on proximal 5q, where CCNB1 and CCNH reside, showed an increased growth rate, suggesting that cyclins activating cdc2, the dominant G2/M phase kinase, may play a role in glioma tumorigenes.

Apoptosis↗

PubMed2001

Alterations of the tumor suppressor genes CDKN2A (p16(INK4a)), p14(ARF), CDKN2B (p15(INK4b)), and CDKN2C (p18(INK4c)) in atypical and anaplastic meningiomas.

We investigated 67 meningothelial tumors (20 benign meningiomas, 34 atypical meningiomas, and 13 anaplastic meningiomas) for losses of genetic information from chromosome arms 1p and 9p, as well as for deletion, mutation, and expression of the tumor suppressor genes CDKN2A (p16(INKa)/MTS1), p14(ARF), CDKN2B (p15(INK4b)/MTS2) (all located at 9p21) and CDKN2C (1p32). Comparative genomic hybridization and microsatellite analysis showed losses on 1p in 11 anaplastic meningiomas (85%), 23 atypical meningiomas (68%), and 5 benign meningiomas (25%). One atypical meningioma with loss of heterozygosity on 1p carried a somatic CDKN2C mutation (c.202C>T: R68X). Losses on 9p were found in five anaplastic meningiomas (38%), six atypical meningiomas (18%), and one benign meningioma (5%). Six anaplastic meningiomas (46%) and one atypical meningioma (3%) showed homozygous deletions of the CDKN2A, p14(ARF), and CDKN2B genes. Two anaplastic meningiomas carried somatic point mutations in CDKN2A (c.262G>T: E88X and c.262G>A: E88K) and p14(ARF) (c.305G>T: G102V and c.305G>A: G102E). One anaplastic meningioma, three atypical meningiomas, and one benign meningioma without a demonstrated homozygous deletion or mutation of CDKN2A, p14(ARF), or CDKN2B lacked detectable transcripts from at least one of these genes. Hypermethylation of CDKN2A, p14(ARF), and CDKN2B could be demonstrated in one of these cases. Taken together, our results indicate that CDKN2C is rarely altered in meningiomas. However, the majority of anaplastic meningiomas either show homozygous deletions of CDKN2A, p14(ARF), and CDKN2B, mutations in CDKN2A and p14(ARF), or lack of expression of one or more of these genes. Thus, inactivation of the G(1)/S-phase cell-cycle checkpoint is an important aberration in anaplastic meningiomas.

Adult↗

PubMed2001

Long-term survival of a patient with giant cell glioblastoma. Case report.

The authors report on a patient who had undergone resection of a left-sided temporal giant cell glioblastoma at the age of 69 years and who survived for more than 17 years. This man had not undergone postoperative radiotherapy or adjuvant chemotherapy. He died at the age of 86 years without clinical evidence of tumor recurrence. Histologically, the lesion was characterized by highly pleomorphic tumor cells (including bizarre multinucleated giant cells) with high mitotic activity, large necroses, and prominent mononuclear infiltration. A point mutation in the TP53 tumor suppressor gene (c.524G>A; R175H) and no epidermal growth factor receptor gene amplification were revealed on molecular genetic analysis. No diagnostic chromosomal imbalances were identified on comparative genomic hybridization, although the average ratio profile for chromosome 10 indicated loss of 10p15 in a subpopulation of tumor cells. This patient is exceptional because tumor resection, probably in conjunction with a marked antitumor immune response, apparently resulted in eradication of the lesion.

Aged↗

PubMed2000

Characterization of genomic alterations in hepatoblastomas. A role for gains on chromosomes 8q and 20 as predictors of poor outcome.

As data on the genomic alterations in hepatoblastoma (HB) are limited, 34 HB tumors and three HB cell lines were screened for DNA copy number changes by comparative genomic hybridization. The average number of chromosomal imbalances per tumor was 2.3 +/- 0.5 (mean +/- SEM) with gains sevenfold more frequent than losses. The most frequent gains of chromosomal material in HB tumors were on 2q (44%), 1q (41%), 2p (29%), 20 (24%), 22q (18%), 8q (15%), 8p and 12q (9% each), as well as 7q, 12p, and 17 (6% each) and the only recurrent loss was on 4q in 12% of cases. Highly amplified sequences were identified in four tumors and mapped to 2q24 in two cases, to 8q in two cases (once to 8q11.2-q13 and once to 8q11.2-q21.3) as well as to 10q24-q26 in one case. In one cell line, highly amplified DNA sequences were mapped to 7p and 8q. Comparison to previously published data on this series of HB revealed that the number of chromosomal imbalances was significantly higher in HB tumors with loss of heterozygosity on 11p (P = 0.03), whereas in five of 10 HB biopsies without chromosomal imbalances, beta-catenin gene mutations were found. HB patients were divided into a good (no evidence of disease) and a poor (died of disease) outcome group according to their clinical course after standard therapy. Two alterations were found to be significantly associated with poor outcome: gain on 8q (P = 0.007) and gain on 20 (P = 0.009). In summary, our analysis allowed the identification of gains on chromosomes 1q and 2 as hallmark DNA copy number changes in HB with 2q24 as a critical chromosomal band. Furthermore, this study provided evidence that gains on 8q and 20 play a role as markers of prognostic significance in HB.

Adolescent↗

PubMed2000

Characteristic chromosomal imbalances in primary central nervous system lymphomas of the diffuse large B-cell type.

We performed a genome wide screening for genomic alterations on a series of 19 sporadic primary central nervous system lymphomas (PCNSL) of the diffuse large B-cell type by comparative genomic hybridization (CGH). The tumors were additionally analyzed for amplification and rearrangement of the BCL2 gene at 18q21 as well as for mutation of the recently cloned BCL10 gene at 1p22. Eighteen tumors showed genomic imbalances on CGH analysis. On average, 2.1 losses and 4.7 gains were detected per tumor. The chromosome arm most frequently affected by losses of genomic material was 6q (47%) with a commonly deleted region mapping to 6q21-q22. The most frequent gains involved chromosome arms 12q (63%), 18q and 22q (37% each), as well as 1q, 9q, 11q, 12p, 16p and 17q (26% each). High-level amplifications were mapped to 9p23-p24 (1 tumor) and to 18q21-q23 (2 tumors). However, PCR-based analysis, Southern blot analysis and high-resolution matrix-CGH of the BCL2 gene revealed neither evidence for amplification nor for genetic rearrangement. Mutational analysis of BCL10 in 16 PCNSL identified four distinct sequence polymorphisms but no mutation. Taken together, our data do not support a role of BCL2 rearrangement/amplification and BCL10 mutation in PCNSL but indicate a number of novel chromosomal regions that likely carry yet unknown tumor suppressor genes or proto-oncogenes involved in the pathogenesis of these tumors.

Apoptosis Regulatory Proteins↗

PubMed1999

Amplification and expression of cyclin D genes (CCND1, CCND2 and CCND3) in human malignant gliomas.

Malignant gliomas frequently show genetic aberrations of genes coding for cell cycle regulatory proteins involved in the control of G1/S phase transition. These include mutation and/or deletion of the retinoblastoma (RB1) gene, homozygous deletion of the CDKN2A and CDKN2B genes, as well as amplification and overexpression of the CDK4 and CDK6 genes. The D-type cyclins (cyclin D1, D2, and D3) promote cell cycle progression from G1 to S phase by binding to and activating the cyclin dependent kinases Cdk4 and Cdk6. Here, we have investigated a series of 110 primary malignant gliomas and 8 glioma cell lines for amplification and expression of the D-type cyclin genes CCND1 (11q13), CCND2 (12p13), and CCND3 (6p21). We found the CCND1 gene amplified and overexpressed in one anaplastic astrocytoma of our tumor series. Two glioblastomas and one anaplastic astrocytoma showed CCND2 gene amplification, but lacked significant overexpression of CCND2 transcripts. Amplification and overexpression of the CCND3 gene was detected in the glioblastoma cell line CCF-STTG1, as well as in one primary glioblastoma and in the sarcomatous component of one gliosarcoma. Our data thus suggest that amplification and increased expression of CCND1 and CCND3 contribute to the loss of cell cycle control in a small fraction of human malignant gliomas.

Blotting, Southern↗

PubMed1999

Chordoid glioma of the third ventricle: immunohistochemical and molecular genetic characterization of a novel tumor entity.

Chordoid glioma of the third ventricle was recently reported as a novel tumor entity of the central nervous system with characteristic clinical and histopathological features (Brat et al., J Neuropathol Exp Neurol 57: 283-290, 1998). Here, we report on a histopathological, immunohistochemical and molecular genetic analysis of five cases of this rare neoplasm. All tumors were immunohistochemically investigated for the expression of various differentiation antigens, the proliferation marker Ki-67, and a panel of selected proto-oncogene and tumor suppressor gene products. These studies revealed a strong expression of GFAP, vimentin, and CD34. In addition, most tumors contained small fractions of neoplastic cells immunoreactive for epithelial membrane antigen, S-100 protein, or cytokeratins. The percentage of Ki-67 positive cells was generally low (<5%). All tumors showed immunoreactivity for the epidermal growth factor receptor and schwannomin/merlin. There was no nuclear accumulation of the p53, p21 (Waf-1) and Mdm2 proteins. To examine genomic alterations associated with the development of chordoid gliomas, we screened 4 tumors by comparative genomic hybridization (CGH) analysis. No chromosomal imbalances were detected. More focussed molecular genetic analyses revealed neither aberrations of the TP53 and CDKN2A tumor suppressor genes nor amplification of the EGFR, CDK4, and MDM2 proto-oncogenes. Our data strongly support the hypothesis that chordoid glioma of the third ventricle constitutes a novel tumor entity characterized by distinct morphological and immunohistochemical features, as well as a lack of chromosomal and genetic alterations commonly found in other types of gliomas or in meningiomas.

Adult↗

PubMed1999

Retention of polysomy at 9p23-24 during karyotypic evolution in human breast cancer cell line COLO 824.

Somatic genetic alterations of 9p have been seen in a wide range of human cancers, including breast cancer. Loss of heterozygosity analysis of primary breast cancer tumors has revealed a high frequency of deletion of DNA from 9p21-22 encompassing the MTSI (P16/CDKN2A) gene. We report the approximately tenfold increase in copy number of DNA from 9p23-24, which is far distal to P16/CDKN2A in female breast cancer cell line COLO 824, as revealed by fluorescence in situ hybridization, comparative genomic hybridization, and microsatellite analysis. Amplification of DNA has been reported previously to encompass multiple sites of the genome of the breast cancer cell, but increase in DNA copy number has not been seen in distal 9p.

Aneuploidy↗

PubMed1998

The human glycine receptor subunit alpha3. Glra3 gene structure, chromosomal localization, and functional characterization of alternative transcripts.

The neuronal glycine receptor is a ligand-gated chloride channel composed of ligand binding alpha and structural beta polypeptides. Homology screening of a human fetal brain cDNA library resulted in the identification of two alternative splice variants of the glycine receptor alpha3 subunit. The amino acid sequence predicted for the alpha3L variant was largely identical to the corresponding rat subunit. In contrast, the novel splice variant alpha3K lacked the coding sequence for 15 amino acids located within the cytoplasmic loop connecting transmembrane spanning region 3 (TM3) and TM4. Using P1 artificial chromosome (PAC) clones, the structure of the GLRA3 gene was elucidated and its locus assigned to human chromosomal bands 4q33-q34 by fluorescence in situ hybridization. Two transcripts of 2.4 and 9 kilobases, corresponding to alpha3L and alpha3K, respectively, were identified and found to be widely distributed throughout the human central nervous system. Structural analysis of the GLRA3 gene revealed that the alpha3K transcript resulted from a complex splice event where excision of the novel exon 8A comprising the alternative sequence of 45 base pairs coincides with the persistence of a large intronic sequence in the 3'-untranslated region. Functional expression in HEK 293 cells of alpha3L and alpha3K subunits resulted in the formation of glycine-gated chloride channels that differed significantly in desensitization behavior, thus defining the cytoplasmic loop as an important determinant of channel inactivation kinetics.

Alternative Splicing↗

PubMed1998

The human glycine receptor beta subunit gene (GLRB): structure, refined chromosomal localization, and population polymorphism.

The glycine receptor of the human CNS comprises ligand-binding alpha 1 and structural beta subunits encoded by the GLRA1 and GLRB genes, respectively. Screening of a human hippocampal cDNA library resulted in the identification of the novel subunit transcript beta B, differing in the 5'-UTR. Analysis of the genomic organization of GLRB showed that the coding region is distributed over nine exons, highly homologous to the GLRA1 gene. By in situ hybridization, the chromosomal localization of GLRB was refined to band 4q31.3. Based on the identical phenotypes of mouse lines carrying mutant alleles of the alpha 1 and beta subunit genes, GLRB was assumed to be a candidate gene for those cases of hyperekplexia that cannot be associated with mutations of GLRA1. Therefore, flanking intronic sequences were determined, and DNA samples from more than 30 index patients were subjected to SSCP screening of the entire GLRB coding region. A polymorphism in exon 8 was found both in the normal population and in families affected by hyperekplexia, although no coding mutation was detectable.

Alleles↗

PubMed1998

Missense mutations in SMOH in sporadic basal cell carcinomas of the skin and primitive neuroectodermal tumors of the central nervous system.

About one-third of sporadic basal cell carcinomas (BCCs) of the skin and 10-15% of primitive neuroectodermal tumors (PNETs) of the central nervous system show mutations in the PTCH tumor suppressor gene. The PTCH gene product (Ptch) functions as a transmembrane receptor for the Sonic hedgehog protein (Shh) and interacts with another transmembrane protein called Smoh. To further elucidate the significance of alterations in the Shh signaling pathway, we investigated 31 sporadic BCCs and 15 PNETs for the mutation and/or expression of SMOH, PTCH, SHH, and GL11. In addition, we fine-mapped the SMOH gene locus by fluorescence in situ hybridization to chromosomal band 7q32. Mutational analysis identified four BCCs with somatic missense mutations in SMOH affecting codon 535 (TGG==>TTG: Trp==>Leu) in three tumors and codon 199 (CGG==>TGG: Arg==>Trp) in one tumor. A missense mutation at codon 533 (AGC==>AAC: Ser==>Asn) was found in one PNET. PTCH mutations were detected in eight BCCs and one PNET. Two BCCs demonstrated mutations in both SMOH and PTCH. The majority of tumors showed an increased expression of SMOH, PTCH, and GL11 transcripts as compared with that of normal skin and nonneoplastic brain tissue, respectively. In contrast, only one BCC and one PNET expressed SHH mRNA at levels detectable by reverse transcription-PCR, and no SHH gene mutations were found. In summary, our results indicate that both PTCH and SMOH represent important targets for genetic alterations in sporadic BCCs and PNETs.

Adolescent↗

PubMed1998

Mutation of the PTEN (MMAC1) tumor suppressor gene in a subset of glioblastomas but not in meningiomas with loss of chromosome arm 10q.

The PTEN (MMAC1) gene, which has been identified as a tumor suppressor gene at 10q23.3, is mutated in multiple malignant tumors, including glioblastomas [J. Li et al., Science (Washington DC), 275: 1943-1947, 1997; P. A. Steck et al., Nat. Genet., 15: 356-362, 1997]. Among tumors of the central nervous system, loss of 10q is not restricted to glioblastomas but is also common in atypical and anaplastic meningiomas. Therefore, we have investigated 36 glioblastomas and 34 meningiomas (2 benign, 17 atypical, and 15 anaplastic meningiomas) for loss on 10q, as well as deletion, mutation, and expression of PTEN. Analysis of eight microsatellites from 10q revealed loss of heterozygosity (LOH) in 25 of 36 glioblastomas (69%). Twenty-three of these tumors demonstrated LOH at all informative loci. Two glioblastomas showed LOH restricted to markers located distally to PTEN, with breakpoints mapping telomeric to D10S541 and D10S185. One glioblastoma demonstrated evidence of homozygous deletion of PTEN by differential PCR analysis. PTEN mutations were detected in 9 of 36 glioblastomas (25%). Seven of these tumors showed LOH at all informative loci from 10q, indicating complete loss of wild-type PTEN. Although loss of 10q was detected by comparative genomic hybridization and/or LOH analysis in 14 of the 34 meningiomas investigated (41%), none of these tumors showed evidence of PTEN mutations or homozygous gene deletions. Our findings corroborate that PTEN is inactivated in a subset of glioblastomas. However, the lack of detectable PTEN alterations in a considerable fraction of glioblastomas and all meningiomas with 10q loss strongly supports the hypothesis that at least one additional tumor suppressor gene is located on 10q.

Adolescent↗

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

A novel orphan G protein-coupled receptor primarily expressed in the brain is localized on human chromosomal band 2q21.

A human hippocampus cDNA library was screened with a probe obtained from degenerate RT-PCR aimed at P2Y-homologous sequences. A positive clone, designated hip4, was identified containing an open reading frame of 1,020 bp that had been previously detected in a published genomic clone called R12. Subsequent screening of a human fetal brain cDNA library yielded a splice variant with a 1,104-bp open reading frame, which was named fb1. Both variants display the seven-transmembrane topology that is typical for G protein-coupled receptors. Probing a human multitissue northern blot revealed two brain-specific transcripts of 2.3 and 6.3 kb, respectively. Northern blot analyses with specific fragments confirmed that the two transcripts are generated by alternative polyadenylation yielding two different 3' untranslated regions. A genomic clone from the corresponding gene was isolated and mapped to human chromosomal band 2q21 by fluorescence in situ hybridization.

Amino Acid Sequence↗