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P Lichter

Publications and source records attributed to P Lichter.

At least 19 recordsLinked to original sources
PubMed2002

[Opportunities and chances for tissue chip microarrays in head and neck surgery. A novel technique for the rapid evaluation of potentially novel biomarkers].

Oral squamous cell carcinomas (OSCC) are malignant tumors with a poor prognosis and low long-term survival rates, even when using modern adjuvant and neoadjuvant therapy forms in addition to surgery. For the clinical estimation of each tumor, it is necessary to define stage-dependent molecular and/or cellular parameters as it is known that OSCC develop along a multistep pathway including the loss of tumor suppressor genes and the amplification of oncogenes which result in changes in protein expression. In order to establish a reliable pattern of molecular and cellular biomarkers, a large number of tumor specimens from different stages of the disease need to be analysed. In this study, biopsies of a collective of 293 OSCC in different stages were screened with the novel technique of tissue chip microarrays by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). FISH-analysis was performed on the oncogene cyclin D1 and IHC-analysis on the proteins cyclin D1, p53, p16, cdk4, bcl2, mdm2 and rb. Tissue chip technology was shown to facilitate rapid screening for molecular and cellular alterations in different stages of OSCC and revealed reliable and reproducible results that may allow the definition of a multistep pathway model for tumor progression in OSCC.

Aged↗
PubMed2002

Topological organization of the MYC/IGK locus in Burkitt's lymphoma cells assessed by nuclear halo preparations.

In Burkitt's lymphoma (BL) cells characteristic chromosomal translocations juxtapose the MYC oncogene to one of the three immunoglobulin (IG) gene loci. This results in deregulation of MYC expression through IG gene enhancer elements. As enhancers and MYC promoters can be as much as several hundred kilobases apart, long-distance effects are to be postulated, which affect chromatin organization. Since transcriptionally active and inactive sequences can be distinguished based on their localization in nuclear halo preparations, we used this technique to assess the topology of wild-type and translocated MYC and IGK genes. Following visualization of these genes by fluorescence in situ hybridization, the signal distribution was determined in nuclear halo structures of human monocytes and the BL-derived cell line LY66. MYC signals derived from the non-translocated chromosome 8 were found equally distributed between the residual nucleus and the surrounding DNA halo. In contrast, the activated MYC and IGK genes on the translocated chromosome in LY66 cells were associated with the residual nucleus in 78 and 88% of cases, respectively. In LY66 cells, attachment to the residual nucleus was restricted to a DNA segment 30 to 50 kb downstream of MYC, while in monocytes it was dispersed over 80 kb around the MYC gene. These findings indicate a specific chromatin organization for the activated MYC locus. Distance measurements between MYC and IGK signals revealed shorter values than expected from their linear distance (325 kb), indicating a back folding of the DNA backbone. Thus, there is strong evidence for a specific topological organization, which is functionally related to the MYC activation status with the specific folding of the DNA strand likely reflecting maintenance of a spatial interaction between IGK enhancer and MYC promoter elements.

Burkitt Lymphoma↗
PubMed2002

Genetics of chronic lymphocytic leukemia: genomic aberrations and V(H) gene mutation status in pathogenesis and clinical course.

The genetic characterization of chronic lymphocytic leukemia (CLL) has made significant progress over the past few years. While conventional cytogenetic analyses only detected chromosome aberrations in 40-50% of cases, new molecular cytogenetic methods, such as fluorescence in situ hybridization (FISH), have greatly enhanced our ability to detect chromosomal abnormalities in CLL. Today, genomic aberrations are detected in over 80% of CLL cases. Genes potentially involved in the pathogenesis were identified with ATM in a subset of cases with 11q deletion and p53 in cases with 17p13 deletion. For the most frequent aberration, the deletion 13q14, candidate genes have been isolated. Genetic subgroups with distinct clinical features have been identified. 11q deletion is associated with marked lymphadenopathy and rapid disease progression. 17p deletion predicts for treatment failure with alkylating agents, as well as fludarabine and short survival times. In multivariate analysis 11q and 17p deletions provided independent prognostic information. Recently, another important issue of genetic risk classification in CLL was identified with the mutation status of the immunoglobulin variable heavy chain genes (V(H)). CLL cases with unmutated V(H) show more rapid disease progression and shorter survival times. Whether CD38 expression can serve as a surrogate marker for V(H) mutation status is currently discussed controversially. V(H) mutation status and genomic abnormalities, such as 17p and 11q deletion, have recently been shown to be related to each other, but were of independent prognostic information in multivariate analysis. Moreover, genomic aberrations and V(H) mutation status appear to give prognostic information irrespective of the clinical stage and may therefore allow a risk assessment for individual patients early in the course of their disease.

Chromosome Aberrations↗
PubMed2001

Nuclear envelope and chromatin compositional differences comparing undifferentiated and retinoic acid- and phorbol ester-treated HL-60 cells.

The human leukemic cell line (HL-60) can be induced to differentiate in vitro to granulocytic form with retinoic acid (RA), or to monocytic/macrophage form with phorbol ester (TPA). The granulocytic form acquires nuclear lobulation, nuclear envelope-limited chromatin sheets (ELCS), and cytoskeletal polarization, none of which are acquired following treatment with TPA. Immunoblotting analyses and capillary zone electrophoresis demonstrated that following RA treatment: lamins A/C and B1, and vimentin decreased to negligible amounts; LAP2 beta, lamin B2 and emerin remained essentially unchanged; lamin B receptor (LBR) increased markedly; histone subtypes H1.4 and 1.5 exhibited dephosphorylation. Following TPA treatment: lamins A/C and B1, B2 and vimentin increased in amount; LAP2 beta and emerin remained essentially unchanged; LBR increased markedly; histone subtypes H1.4 and 1.5 exhibited dephosphorylation. Emerin, which was cytoplasmic in undifferentiated or granulocytic cells, localized into the nuclear envelope following TPA. Normal human granulocytes revealed compositional differences compared to granulocytic forms of HL-60, namely increased vimentin and appearance of histone subtype H1.3. A working hypothesis for nuclear lobulation postulates a combination of: increased nuclear envelope deformability due to lamins A/C and B1 deficiency; an increase in nuclear surface area/volume; an increase in chromatin-nuclear envelope interactions.

Cell Compartmentation↗
PubMed2001

B-cell neoplasia associated gene with multiple splicing (BCMS): the candidate B-CLL gene on 13q14 comprises more than 560 kb covering all critical regions.

Deletions in chromosomal band 13q14.3 occur in >50% of B-cell chronic lymphocytic leukemias (B-CLL) and mantle cell lymphoma, indicating the localization of a tumor suppressor gene involved in the pathomechanism of these diseases. Within a 400 kb recurrently deleted segment at least two minimally deleted subregions had been reported. For the two genes residing in the proximal subregion, initially named LEU1 and LEU2, a pathogenic role has not yet been established. We report here that LEU1 is only a small portion of a large gene, which spans all previously reported critical subregions including the distal subregion. This gene, designated B-cell neoplasia-associated gene with multiple splicing (BCMS), is composed of at least 50 exons spanning >or=560 kb of genomic DNA and is expressed in more than 20 RNA splicing variants. While tissue-specific expression of RNA variants was observed, there was no evidence for the expression of a variant specific for B-CLL. Sequence analysis of the RNA variants suggests that BCMS transcripts belong to the group of non-coding RNAs. The alignment of the gene with all critical subregions provides a strong argument for BCMS being the most likely candidate for the tumor suppressor gene in 13q14 involved in the leukemogenesis of B-CLL. Due to the limited understanding of functional RNAs, however, it remains difficult to prove the pathogenic role of BCMS.

Alternative Splicing↗
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

CDNA microarray gene expression analysis of B-cell chronic lymphocytic leukemia proposes potential new prognostic markers involved in lymphocyte trafficking.

Human cancer is characterized by complex molecular perturbations leading to variable clinical behavior, often even in single-disease entities. We performed a feasibility study systematically comparing large-scale gene expression profiles with clinical features in human B-cell chronic lymphocytic leukemia (B-CLL). cDNA microarrays were employed to determine the expression levels of 1,024 selected genes in 54 peripheral blood lymphocyte samples obtained from patients with B-CLL. Statistical analyses were applied to correlate the expression profiles with a number of clinical parameters including patient survival and disease staging. We were able to identify genes whose expression levels significantly correlated with patient survival and/or with clinical staging. Most of these genes code either for cell adhesion molecules (L-selectin, integrin-beta2) or for factors inducing cell adhesion molecules (IL-1beta, IL-8, EGR1), suggesting that prognosis of this disease may be related to a defect in lymphocyte trafficking. This report demonstrates the feasibility of a systematic integration of large-scale gene expression profiles with clinical data as a general approach for dissecting human diseases.

Adult↗
PubMed2001

Loss of the Y chromosome is a frequent chromosomal imbalance in pancreatic cancer and allows differentiation to chronic pancreatitis.

In a study for the identification of genomic alterations in pancreatic cancer, representational difference analysis was used and led to the isolation of 2 distinct fragments, deleted on the Y chromosome in the xenografted tumor DNA of a male patient with an adenocarcinoma of the pancreas. Loss of Y chromosomal material was further studied in 11 pancreatic cancer cell lines of male origin, using PCR amplification of 5 sequence tagged sites (STSs) distributed along the Y chromosome; 8/11 cell lines exhibited a complete loss of the Y chromosome and 3 had deletions. To examine the status of the Y chromosome in situ, interphase FISH analysis was performed on paraffin sections from pancreatic carcinoma (n=7) and chronic pancreatitis (n=7) tissues, and the loss of Y-chromosomal STS-markers was studied in 6 xenograft tumors obtained from male pancreatic cancer patients. This analysis revealed that a loss of the Y chromosome occurs in vivo in primary pancreatic tumor cells, whereas the Y chromosome was intact in chronic pancreatitis. Our data suggest that loss of Y is a frequent event occurring in male pancreatic tumors. Although there is no evidence for a functional implication of Y chromosome loss, it effectively differentiates between a malignant and a benign condition as e.g. chronic pancreatitis. Thus, this genetic alteration may be of diagnostic use.

Animals↗
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

Gain of chromosome arm 9p is characteristic of primary mediastinal B-cell lymphoma (MBL): comprehensive molecular cytogenetic analysis and presentation of a novel MBL cell line.

Primary mediastinal B-cell lymphoma (MBL) is an aggressive Non-Hodgkin's Lymphoma, which has been recognized as a distinct disease entity. We performed a comprehensive molecular cytogenetic study analyzing 43 MBLs. By comparative genomic hybridization (CGH), the most common aberrations were gains of chromosome arms 9p and Xq, which were present in 56% and 40% of cases, respectively. Based on the limited resolution of CGH, this technique may underestimate the real incidence of aberrations. Therefore, we also did an interphase cytogenetic study with eight DNA probes mapping to chromosome regions frequently altered in B-cell lymphomas. With this approach, both 9p and Xq gains were found in more than 70% of cases (75% and 87%, respectively). The findings were compared with results obtained in 308 other B-cell lymphomas. Gains in 9p were identified in only six of the 308 cases, and only one of these lymphomas with 9p gains was not primarily extranodal in origin (P < 10-(20) for CGH data and P < 10-(11) for fluorescence in situ hybridization data). We also present a novel MBL cell line, MedB-1, which carries the genetic aberrations characteristic of this entity.

Adolescent↗
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

Pbx4, a new Pbx family member on mouse chromosome 8, is expressed during spermatogenesis.

Members of the Pbx family are involved in a diverse range of developmental processes including axial patterning and organogenesis. Pbx functions are in part mediated by the interaction of Pbx proteins with members of the Hox and Meis/Prep families. We have identified a fourth mammalian Pbx family member. Pbx4 in the mouse and PBX4 in humans are located on chromosome 8 and chromosome 19, respectively. Pbx4 expression is confined to the testis, especially to spermatocytes in the pachytene stage of the first meiotic prophase.

Amino Acid Sequence↗
PubMed2001

MDM2 gene amplification and lack of p53 point mutations in Hodgkin and Reed-Sternberg cells: results from single-cell polymerase chain reaction and molecular cytogenetic studies.

Hodgkin's disease (HD) is the most common haematological malignancy after chronic lymphocytic leukaemia, but very little is known about its pathogenesis or the genetic events that contribute to the malignant phenotype of the tumour cells. p53 is assumed to play an important role in the pathogenesis of HD, based on the observation that p53 protein is frequently accumulated in Hodgkin and Reed-Sternberg (H & RS) cells. We investigated single H & RS cells from five different HD patients for point mutations at the genomic level using multiplex polymerase chain reaction amplification and subsequent sequencing. No point mutations were detected in 50 single H & RS cells analysed. Hence, accumulation of p53 protein cannot be explained by mutations within the gene. A genome-wide screening for genomic imbalances using comparative genomic hybridization revealed gain on chromosome 12q14, i.e. the mapping position of the MDM2 gene in several HD cases. Therefore, we assessed the copy number of the MDM2 gene using fluorescence in situ hybridization. In four out of six HD cases analysed, the copy number of the MDM2 gene was found to be increased. As gene amplification is frequently associated with protein overexpression, the observed accumulation of p53 in the nuclei of H & RS cells could be as a result of elevated MDM2 protein levels resulting in stabilization of p53 protein.

Adult↗
PubMed2000

Genomic aberrations and survival in chronic lymphocytic leukemia.

BACKGROUND: Fluorescence in situ hybridization has improved the detection of genomic aberrations in chronic lymphocytic leukemia. We used this method to identify chromosomal abnormalities in patients with chronic lymphocytic leukemia and assessed their prognostic implications. METHODS: Mononuclear cells from the blood of 325 patients with chronic lymphocytic leukemia were analyzed by fluorescence in situ hybridization for deletions in chromosome bands 6q21, 11q22-23, 13q14, and 17p13; trisomy of bands 3q26, 8q24, and 12q13; and translocations involving band 14q32. Molecular cytogenetic data were correlated with clinical findings. RESULTS: Chromosomal aberrations were detected in 268 of 325 cases (82 percent). The most frequent changes were a deletion in 13q (55 percent), a deletion in 11q (18 percent), trisomy of 12q (16 percent), a deletion in 17p (7 percent), and a deletion in 6q (7 percent). Five categories were defined with a statistical model: 17p deletion, 11q deletion, 12q trisomy, normal karyotype, and 13q deletion as the sole abnormality; the median survival times for patients in these groups were 32, 79, 114, 111, and 133 months, respectively. Patients in the 17p- and 11q-deletion groups had more advanced disease than those in the other three groups. Patients with 17p deletions had the shortest median treatment-free interval (9 months), and those with 13q deletions had the longest (92 months). In multivariate analysis, the presence or absence of a 17p deletion, the presence or absence of an 11q deletion, age, Binet stage, the serum lactate dehydrogenase level, and the white-cell count gave significant prognostic information. CONCLUSIONS: Genomic aberrations in chronic lymphocytic leukemia are important independent predictors of disease progression and survival. These findings have implications for the design of risk-adapted treatment strategies.

Adult↗
PubMed2000

BCMSUN, a candidate gene for B-cell chronic lymphocytic leukemia and mantle-cell lymphoma, has an independently expressed homolog on 1p22-p31, BCMSUN-like.

The most frequent chromosomal imbalance in B-cell chronic lymphocytic leukemia (B-CLL) and mantle-cell lymphoma (MCL) is loss of material from 13q14.3. BCMSUN (previously Leu2, t4, cDNA 1B4) is one of 3 proposed candidate genes isolated from the minimally deleted region. We identified a homolog of BCMSUN, termed BCMSUNL (for BCMSUN-like). Radiation-hybrid mapping with a PCR-amplified fragment and fluorescence in situ hybridization with 2 PAC clones containing coding information for BCMSUNL revealed its localization at 1p22-p31. Interphase fluorescence in situ hybridization, however, revealed that the BCMSUNL gene locus is not part of the critical deletion region of 1p22 in MCLs. Analysis of DNA sequences derived from the respective PAC clones and available in public databases uncovered an intronless structure of BCMSUNL. Compared to BCMSUN, the new gene lacks exon 2 and shows 90.3% homology on the nucleic acid level. Both genes are expressed in peripheral blood lymphocytes from healthy donors as well as B-CLL and MCL tumors, with retention of genetic material at 13q14.3. Therefore, analysis of the candidate tumor-suppressor gene BCMSUN at 13q14.3 must be based on assays that distinguish between the 2 homologous genes.

Base Sequence↗
PubMed2000

Low grade fibromyxoid sarcoma. a further low-grade soft tissue malignancy characterized by a ring chromosome.

Supernumerary rings in the context of a simple karyotype characterize several low-grade malignant tumors of soft tissue and bone. Low-grade fibromyxoid sarcoma is an uncommon low-grade sarcoma, the cytogenetics of which has not yet been reported. Here we describe the first molecular-cytogenetic characterization of a pulmonary metastasis of low-grade fibromyxoid sarcoma. The histology of the primary and recurrent tumors was consistent with the diagnosis of low-grade fibromyxoid sarcoma of the usual type, whereas the pulmonary metastasis was of the "giant rosettes" variant. Cytogenetic analysis revealed a ring chromosome. Because gain of material of chromosomes 7 and 16 was detected by CGH, the ring chromosome is assumed to be composed of material from these respective chromosomes.

Adult↗