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D J Venter

Publications and source records attributed to D J Venter.

47 records · Page 3Linked to original sources
PubMed1992

Molecular genetic study showing that the IN/157 'oligodendroglioma' cell line has been contaminated by rhabdomyosarcoma (RD) cells.

The IN/157 cell line was originally isolated from a human oligodendroglioma biopsy and has been used in recent years to study aspects of glioma cell biology. We established that IN/157 cells carry a relatively infrequent mutation at position three of codon 61 of the N-ras gene, suggesting that such a mutation may have contributed towards the genesis of the original tumour. However, the mutation was not detectable within the original paraffin-embedded glioma biopsy from which the cell line was supposedly derived. We thus considered the possibility that the cells had been contaminated by another cell line and, by means of DNA fingerprinting, have demonstrated that the contaminating cell line is the rhabdomyosarcoma line RD. We feel that this study makes several important points regarding experiments which make use of cell lines. We discuss the possible implications of contamination events with regard to erroneous conclusions about the biology of the cell lines and tumour types from which they supposedly derive. We also suggest ways in which future contamination-related errors can be minimized.

Base Sequence↗
PubMed1991

Multiple sequential molecular abnormalities in the evolution of human gliomas.

We have examined a series of 13 benign and 27 malignant human gliomas for evidence of molecular abnormalities of proto-oncogene and putative tumour suppressor gene loci. The results indicated that specific molecular lesions were associated with increasing grades of malignancy. Thus, loss of genetic material on chromosome 17 was present with approximately equal frequency in both benign and malignant gliomas, whereas loss of loci on chromosome 10 was seen only in malignant gliomas. Only the most malignant tumours, known as glioblastoma multiforme, had more than one molecular abnormality in the same tumour. These findings may contribute to our understanding of glial tumour development, as well as improve the accuracy of tumour diagnosis.

Chromosome Deletion↗
PubMed1991

Expression of growth factor receptors in human brain tumours.

The expression of the EGF receptor, c-erbB-2 and PDGF receptor proteins has been studied in a series of human brain tumour biopsies and cell lines. Western blotting was used to determine the amount of protein present and their intrinsic and ligand promoted enzyme activities were studied by immunoprecipitation followed by autophosphorylation. EGF receptors were found to be expressed at very high levels in 40% of primary tumour biopsies, but at uniformly low levels in tumour derived cell lines. The c-erbB-2 protein was not detected in tumour biopsies, but was present at variable, but low levels in extracts of tumour cell lines. PDGF receptors were also found at moderate to low levels in both primary tumours and cell lines. The EGF receptor gene was amplified in four out of 14 primary tumours and this generally correlated with high levels of protein expression. The c-erbB-2 gene was not amplified. Employing the polymerase chain reaction and sequence specific oligonucleotides as probes there was no evidence of mutations in the c-erbB-2 gene transmembrane region. These results suggest that alterations of expression of the EGF receptor may play a role in human brain tumours. There was however no evidence for aberrant expression of the c-erbB-2 protein. Additional experiments are required to assess the influence of PDGF receptor expression in brain tumour cells.

Brain Neoplasms↗
PubMed1991

Retinoblastoma gene deletions in human glioblastomas.

The retinoblastoma susceptibility gene, RB, is the best characterised of the tumour suppressor genes, or 'anti-oncogenes'. Abnormal function of the RB protein is thought to result in loss of an inhibitory effect on cell growth, and thus contribute towards the development of certain human cancers. One group of human cancers of particular interest in relationship to retinoblastoma gene function are the gliomas, which are central nervous system tumours thought to originate from the neuroectoderm, the embryological tissue which also gives rise to retinoblastomas. We have therefore examined a group of benign and malignant gliomas for evidence of structural alterations of the RB gene. Four out of nine (44%) glioblastomas, the most malignant gliomas, showed loss of heterozygosity of a locus within this gene. In addition, one of these hemizygous tumours showed deletion of part of the RB protein-coding region, and this abnormality was also present in cells cultured from the tumour. These findings suggest that RB gene abnormalities may contribute to the development of glioblastomas.

Alleles↗
PubMed1987

Overexpression of the c-erbB-2 oncoprotein in human breast carcinomas: immunohistological assessment correlates with gene amplification.

Amplification of the human protooncogene c-erbB-2 was found in 12 of 36 human breast tumours and was associated with increased levels of expression of the c-erbB-2 protein, measured both by immunohistological staining and by western blotting. The use of immunohistological staining to detect the level of expression of the c-erbB-2 protein in human breast adenocarcinomas may be of value in predicting tumour behaviour.

Adenocarcinoma↗
PubMed1987

Immunohistochemical localization of c-erbB-2 in human breast carcinomas.

This study was carried out to assess the utility of antibodies raised to synthetic peptides of the predicted sequence of the c-erbB-2 gene product to identify immunocytochemically those tumours overexpressing this putative transmembrane receptor. Staining with rabbit antiserum 21N gave the best correlation with gene amplification and did not stain the membrane of any of the normal tissues at the dilution which strongly stained the membrane of any of the normal tissues at the dilution which strongly stained the amplified tumours. No significant correlation was found with lymph node involvement, epidermal growth factor receptor status or with oestrogen receptor levels. Of the 12 out of 34 cases which demonstrated c-erbB-2 gene amplification in the primary tumour, two had lymph node metastases which were also positive immunocytochemically. Fourteen other cases which had lymph node metastases were negative in the primary tumour and in the metastases. These tumours all showed strong membrane positivity. A comparison of modified methacarn and formol saline fixation demonstrated an increased sensitivity with the former, but the staining pattern was unaltered. This small but extensively studied group of cases has indicated that increased c-erbB-2 protein can be identified routinely in fixed tissue sections, making it possible to carry out extensive studies to look for clinical correlates, but also to assess the stage in tumour progression at which the increased expression occurs and whether it correlates with any potentially premalignant condition.

Breast Neoplasms↗
PubMedDate not supplied

EWS/FLI-1 fusion transcript detection and MIC2 immunohistochemical staining in the diagnosis of Ewing's sarcoma.

Ewing's sarcoma (ES) and other primitive peripheral neuroectodermal tumors (pPNETs) can present a significant diagnostic problem, as they may morphologically resemble other small round cell tumors (SRCTs) of childhood. However, ES/pPNET is known to carry a characteristic t(11;22)(q24;q12), the detection of which may aid diagnosis. The recent identification of the EWS and FLI-1 genes flanking the translocation break point has enabled reverse transcriptase-polymerase chain reaction (RT-PCR) to be used to detect the putative chimeric transcription factor mRNA produced by the fusion gene. We have assessed the RT-PCR method of detection by examining 40 cases of ES for the presence of EWS/FLI-1 transcripts. Twenty-six (76%) of the 34 cases with intact mRNA yielded fusion transcripts. Four different transcript sizes were detected and two tumors contained two transcripts of different size. No transcripts were detected in a control group of non-ES/pPNET SRCTs. Eight cases with intact mRNA were transcript negative. The MIC2 cell surface antigen, which is reported to be present in over 95% of ES/pPNETs, was present in 32 of 33 tumors (97%), including all 24 EWS/FLI-1 transcript-positive cases examined. Hence MIC2 is a useful screen for ES, with RT-PCR detection of t(11;22) being the optimal method for confirming the diagnosis.

12E7 Antigen↗
PubMedDate not supplied

Molecular analysis in the diagnosis of pediatric lymphomas.

Thirty-five pediatric lymphomas were categorized as either Burkitt's lymphoma (BL), lymphoblastic lymphoma (LL), or large cell anaplastic lymphoma (LCAL) by histological and immunophenotypic methods. They were further characterized by molecular analysis of their antigen receptor genes. Southern blot (SB) and polymerase chain reaction (PCR) techniques were compared in the detection of immunogloblin heavy chain gene (IgH) rearrangement. T cell receptor beta (TCR beta) rearrangements were analyzed by SB and TCR gamma gene rearrangements by PCR. The PCR method of IgH and TCR gamma gene analysis was preferred to the SB methods, because there were fewer equivocal results in IgH gene analysis, TCR gamma rearrangement was more frequently detected than TCR beta in both lymphoblastic and large cell anaplastic lymphomas, and the PCR technique was more rapid, required less DNA, and could be used with archival material. In addition, analysis of IgH gene rearrangement by PCR was more specific for assessing B cell lineage. Although most of the molecular data were easily interpreted, occasional ambiguous results were seen due to genetic events other than antigen receptor gene rearrangement affecting the genetic analysis. Thus, it is imperative to interpret these genetic data in the context of adequate morphological and immunophenotypic analysis.

Blotting, Southern↗
PubMedDate not supplied

Squamous cell carcinoma of the tongue in a child with Fanconi anemia: a case report and review of the literature.

This report documents a case of squamous cell carcinoma (SCC) of the tongue in a child with Fanconi anemia (FA). FA is an autosomal recessive syndrome defined by chromosomal breakage in response to diepoxybutane or mitomycin C in which many patients present with pancytopenia, hypoplastic bone marrow, hyperpigmentation of the skin, skeletal malformations, small stature, hypogonadism, and chromosomal aberrations. Such patients are prone to the development of hematological malignancies and squamous cell carcinoma, especially of the head and neck. Although FA appears to be genetically heterogeneous, all cases display abnormalities of DNA repair. A gene defective in one of the four subsets of FA patients has been defined. Defects in this gene are thought to play a role in the development of neoplasia in FA patients. However, many other factors may also contribute to the development of malignancies, including immune deficiencies, therapeutic strategies, and bone marrow transplantation. This report reviews the association of FA and SCC and highlights the many factors involved in the development of neoplasia within a single patient, including FA, cyclophosphamide, immunosuppression, X-irradiation, and chronic oral graft-versus-host disease. In addition, the human papillomavirus status, although negative, is documented for the first time in such a case.

Adolescent↗
PubMedDate not supplied

Coexistent T-cell lymphoblastic lymphoma and an atypical myeloproliferative disorder associated with t(8;13)(p21;q14).

This report describes a neoplasm exhibiting both lymphoid and myeloid differentiation associated with an acquired balanced translocation between chromosomes 8 and 13 occurring in a 10-year-old boy. Serial lymph node biopsies revealed the presence of both lymphoblastic lymphoma and an atypical myeloproliferative disorder within the same node. Immunophenotyping was consistent with the presence of an immature T-cell population within the nodal biopsy specimens. Cytogenetic analysis of the bone marrow and lymph node biopsy specimens revealed a unique translocation, t(8;13) (p21;q14). Molecular analysis revealed rearrangement of the immunoglobulin heavy chain gene and germline configuration of the T-cell receptor gene. The patient had a poor response to classical T-cell acute lymphocytic leukemia/lymphoma therapy and was changed to a myeloid leukemia protocol with good response. He underwent bone marrow transplantation but died soon after of overwhelming graft-versus-host disease. We found five similar cases in the literature, suggesting the existence of a subset of mixed lymphoid/myeloid disorders with 8p;13q translocations, in which the clinical picture is dictated by the myeloid element.

Child↗