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H Taubert

Publications and source records attributed to H Taubert.

At least 55 records · Page 3Linked to original sources
PubMed1998

[Liposomal DNA transfection of human sarcoma cells with p53 alterations].

An vital assay allows to optimize liposomal transfection for human tumor cells via FACS. Various cationic lipids were tested to analyse the reporter gene expression (green fluorescent protein, GFP) in different soft tissue sarcoma (STS) cells with known genetic alterations. Furthermore, the cellular uptake of fluorescence-labeled oligodeoxynucleotides (ODN's) was determined. The results obtained with two self-established sarcoma cell lines (LMS6-93, US8-93) were compared with ATCC sarcoma cell lines (Saos-2, A-204, RD) and fibroblast cells. We found maximal 37% cells expressing GFP 24 h post-transfection. All mesenchymal (tumor) cells but not fibroblast cells could be transfected in a cell-specific and lipid-dependent manner. In kinetic studies highest transfection rates were determined between 24 and 48 h, whereas the GFP expression is downregulated after 72 h. Furthermore, we found transfectability is p53 mutation-independent and a relative low toxicity of the new lipids (Lipotaxi and Clonfectin) in comparison to other lipids (Lipofectin, Lipofectamine). By a cell sorting system sarcoma cell lines expressing the reporter gene could be enriched up to 84% of the living cell population. Labeled ODN's were taken up more efficiently (> 90%) when they were mixed with lipids before, but ODN's alone were incorporated into sarcoma cells only in a low percentage (< 10%) and concentration. STS cell cultures showed also a relative high ODN uptake compared with cell lines. We propose the liposomal transfection strategy as an efficient method which can be applied to adherent-growing tumor cells. The method allows simultaneously to study transfection rates, apoptosis and cell cycle alterations in vitro. Furthermore, in future, extension on ex vivo and in vivo transgene expression (xenotransplanted sarcomas) will be evaluated.

Gene Expression Regulation, Neoplastic↗
PubMed1998

[Frequency, distribution and prognostic relevance of p53 mutations in soft tissue sarcomas].

Soft tissue sarcomas although rarely occurring (about 1% of malignant tumors), are because of their histo-morphological diversity and often similar appearance to tumor-like lesions difficult to characterize and estimate in their tumor biological behaviour. Analysis of molecular characteristics as alterations in tumor-suppressor and oncogenes may allow insight in STS genesis. We have chosen the in carcinomas well, but in STS not comprehensively investigated tumor-suppressor gene p53 for mutational analysis. In 16 out of 146 STS patients we could identify p53-mutations. In a multivariate Cox-regression analysis prognosis was correlated with the p53-mutation type. However, only patients with non-frameshift mutations possessed a poorer prognosis (RR = 2.42; p = 0.014) in comparison to patients without mutations, but frameshift-mutations didn't seem to affect prognosis negatively. Compiling our results and those of the literature an overall frequency of 16.3% of p53-mutations in STS, with various frequencies in different entities is detectable. STS specific hotspots are not recognizable. Rather mutational hotspots in codons 175, 245, 248 and 273 well known from studies in carcinomas are also apparent in STS. Summarizing, we want to state that the occurrence of p53-mutations (non-frameshift mutations) is of prognostic importance in STS. Combination of histo-pathological, clinical and molecular characteristics may allow to distinguish in future different groups of patients for an individual treatment.

Codon↗
PubMed1998

[p53 overexpression as independent prognostic marker in soft tissue sarcomas is antibody dependent].

Most changes in p53 result in a protein with prolonged half life. This permits immunohistochemical detection. P53-overexpression seems to have prognostical relevance in soft tissue sarcomas (STS). The goal of this study was to compare the prognostic relevance of five different p53 antibodies in immunohistochemistry of primary STS using a Cox regression model with adjustment to staging, localization, tumor type, and surgical therapy. We investigated 198 primary STS of six different tumor types for p53-overexpression using the antibodies DO-1, DO-7, Pab1801, Pab240, and CM-1. The rate of positivity (cut of point 10% positive tumor cells) was between 36.2% and 62.6% dependent on the applied antibody. Prognostic significance could be determined only for the N-terminal binding monoclonal antibodies (DO-1, p = 0.0014; DO-7, p = 0.005; Pab1801, p = 0.02) with the highest level for combination of DO-7 and Pab1801 positivity (RR = 2.57, p = 0.0098). Pab240 (epitope amino acids 213-217) and CM-1 (polyclonal) showed no prognostic relevance in the multivariate analysis. We therefore suggest that for immunohistochemical evaluation of p53-overexpression in STS a pannel of two N-terminal antibodies should be used at least.

Antibodies, Monoclonal↗
PubMed1997

Mechanism and Bicoid-dependent control of hairy stripe 7 expression in the posterior region of the Drosophila embryo.

Pair-rule gene hairy (h) expression in seven evenly spaced stripes, along the longitudinal axis of the Drosophila blastoderm embryo, is mediated by a modular array of separate stripe enhancer elements. The minimal enhancer element, which generates reporter gene expression in place of the most posterior h stripe 7 (h7-element), contains a dense array of binding sites for factors providing the trans-acting control of h stripe 7 expression as revealed by genetic analyses. The h7-element mediates position-dependent gene expression by sensing region-specific combinations and concentrations of both the maternal homeodomain transcriptional activators, Caudal and Bicoid, and of transcriptional repressors encoded by locally expressed zygotic gap genes. Caudal and Bicoid, which form complementing concentration gradients along the longitudinal axis of the embryo, function as redundant activators, indicating that the anterior determinant Bicoid is able to activate gene expression in the most posterior region of the embryo. The spatial limits of the h stripe-7 domain are brought about by the local activities of repressors which prevent activation. The results suggest that the gradients of Bicoid and Caudal combine their activities to activate segmentation genes along the entire axis of the embryo.

Animals↗
PubMed1997

Prognostic value of immunohistochemistry for p53 in primary soft-tissue sarcomas: a multivariate analysis of five antibodies.

Most changes of tumor suppressor p53 and its pathway involve a protein with prolonged half-life that permits immunohistochemical detection. The goal of this study was to compare the prognostic relevance of five different p53 antibodies in primary soft-tissue sarcomas (STS) with known p53 mutation status, using a multivariate Cox regression model (adjusted to tumor grading, staging, localization, tumor type, and therapy). A group of 198 primary STS of six types were investigated for p53 overexpression, using p53 antibodies DO-1, DO-7, Pab1801, Pab240, and CM-1. A positive marker frequency between 36.2% and 62.6% was detected. Out of 65 patients whose primary tumor reacted positively to all five antibodies, 52 (80%) died within the study period. Only the N-terminal-binding monoclonal antibodies DO-1, DO-7 and Pab1801 showed a multivariate correlation with survival (P = 0.0014, 0.0048 and 0.02). CM-1 and Pab240 had a univariate, but not a multivariate correlation, with a confounding effect of grading. The prognostic relevance for the five p53 antibodies was: DO-1 > Pab1801 > DO-7 > CM-1 > Pab240. This is the first study that investigates multivariately the prognostic relevance of p53 immunostaining in STS. If monoclonal antibodies with an epitope in the N-terminal region of the p53 protein (DO-1, Pab1801, DO-7) are applied, p53 immunohistochemistry provides an independent prognostic marker in STS.

Antibodies, Monoclonal↗
PubMed1997

Immunohistochemical and clinical evaluation of cathepsin expression in soft tissue sarcomas.

Lysosomal proteases are known to enhance the spread of epithelial tumour cells, but little is known of the possible role of proteases in the growth of soft tissue sarcomas (STS). We investigated the expression of cathepsins D, B, S, H, L and procathepsin L in frozen sections of 34 STS from 34 patients by immunohistochemistry (IHC). Cathepsins D, B and H were relatively highly expressed in STS (77-91%). The expression rate of cathepsins S and L and of procathepsin L was lower (40-66%). Cathepsin S and L expression showed a moderate (P = 0.078 and P = 0.019) and procathepsin L a strong (P = 0.00001) correlation with the survival rate of STS patients. Cathepsin S expression is also correlated with the local recurrence rate (P < 0.01). Lysosomal proteases may play a role in STS progression, and cathepsin expression may also have significance as a prognostic factor in STS.

Adult↗
PubMed1997

Regulation of Drosophila spalt gene expression.

The region-specific homeotic gene spalt is involved in the specification of terminal versus trunk structures during early Drosophila embryogenesis. Later in development spalt activity participates in specific processes during organogenesis and larval imaginal disc development. The multiple functions of spalt are reflected in distinct spatio-temporal expression patterns throughout development. Here we show that spalt cis-regulatory sequences for region-specific and organ-specific expression are clustered. Their organization may provide the structural basis for the diversification of expression pattern within the spalt/spalt related/spalt adjacent gene complex. We also examined the transacting factor requirement for the blastodermal spalt expression domains. They are under the genetic control of maternal and gap gene products and we show that these products are able to bind to corresponding spalt cis-acting sequences in vitro. The results suggest that the transacting factors, as defined by genetic studies, functionally interact with the spalt regulatory region. In addition, we provide evidence that a zygotic gene product of the terminal system, Tailless, cooperates with the maternal gene product Caudal and thereby activates gene expression in the terminal region of the embryo.

Animals↗
PubMed1997

Embryonic expression and characterization of a Ptx1 homolog in Drosophila.

We describe the molecular characterization of the paired-type homeobox gene D-Ptx1 of Drosophila, a close homolog of the mouse pituitary homeobox gene Ptx1 and the unc-30 gene of C. elegans, characterized by a lysine residue at position 9 of the third alpha-helix of the homeodomain. D-Ptx1 is expressed at various restricted locations throughout embryogenesis. Initial expression of D-Ptx1 in the posterior-most region of the blastoderm embryo is controlled by fork head activity in response to the activated Ras/Raf signaling pathway. During later stages of embryonic development. D-Ptx1 transcripts and protein accumulate in the posterior portion of the midgut, in the developing Malpighian tubules, in a subset of ventral somatic muscles, and in neural cells. Phenotypic analysis of gain-of-function and lack-of-function mutant embryos show that the D-Ptx1 gene is not involved in morphologically apparent differentiation processes. We conclude that D-Ptx1 is more likely to control physiological cell functions than pattern formation during Drosophila embryogenesis.

Amino Acid Sequence↗
PubMed1997

Prognostic relevance of C-terminal Mdm2 detection is enhanced by p53 positivity in soft tissue sarcomas.

We examined the clinical value of immunohistochemical (IHC) Mdm2 detection by an N-terminal (IF2) and a C-terminal (19E3) binding monoclonal antibody (Ab) in soft tissue sarcomas (STSs) with regard to the p53 status. Therefore, we investigated a cohort of 198 patients with STSs of six entities with known p53 IHC by using a multivariate Cox regression model to determine the prognostic value of Mdm2 staining. Only positivity with the 19E3 Ab correlated multivariately significantly with survival (RR = 2.32, p = 0.0035). We stratified the C-terminal Mdm2 staining (19E3) according to p53 IHC (DO-1) and found patients could be divided into three groups with an increasing risk: (a) patients with Mdm2 (19E3)-negative as well as p53 (DO-1)-negative tumors, (b) patients with tumors that were either Mdm2 (19E3) or p53 (DO-1) positive, and (c) patients with tumors that were Mdm2 (19E3) as well as p53 (DO-1) positive. Positive staining for both Mdm2 and p53 meant a very poor prognosis with a relative risk of 4.63 (p = 0.00001). This points to the possibility that--in addition to the p53-dependent pathway--Mdm2 could have an effect through a p53-independent pathway. Thus, our results indicate that C-terminal Mdm2 staining (19E3) constitutes an independent prognostic marker in STS.

Adolescent↗
PubMed1997

Detection of p53 autoantibodies in sera of gastric cancer patients and their prognostic relevance.

BACKGROUND: Changes in the p53 gene product can be immunogenic and enable the formation of p53 serum antibodies (p53ab), detectable in patients with different cancer types. So far, there have been no reports describing the detectability of p53ab in gastric cancer patients. METHODS: We investigated the presence of p53ab and their clinical relevance in a cohort of 74 gastric cancer patients, using an enzyme-linked immunosorbent assay system. RESULTS: In our investigation 20.3% of all patients (15 of 74) and 46.9% of the patients with immunohistochemically (IHC) p53-positive tumors (15 of 32) showed detectable p53ab in serum. All p53ab-positive patients had IHC p53-positive tumors. We have found a significant correlation of p53ab with a higher tumor stage (P = 0.002) and also with a poor prognosis of survival (P = 0.04). CONCLUSION: We have shown that in gastric cancer patients p53ab are also detectable and that p53ab positivity is a predictor of an unfavorable prognosis.

Adult↗
PubMed1996

Prognosis is correlated with p53 mutation type for soft tissue sarcoma patients.

We investigated the prognostic value of p53 mutation type for 145 soft tissue sarcoma patients. In a PCR-SSCP-sequencing analysis, 15 mutations were identified: 10 non-frameshift (non-fs) and 5 frameshift (fs) mutations. Patients possessing non-fs mutations had a significantly poorer prognosis than patients without p53 mutations (P = 0.014), according to Cox's multivariate analysis. In contrast, the survival of five patients with fs mutations was not affected by their mutation type. Furthermore, occurrence of lymph node metastases and recurrences was correlated with the mutation type; i.e., 4 of 10 and 5 of 10 patients with non-fs mutations showed lymph node metastases and recurrences, respectively, whereas none of the patients with fs mutations showed lymph node metastases and only one a recurrence. Therefore, for the evaluation of prognosis, we suggest applying not the p53 mutational status in general, but the specific type of mutation.

Adult↗
PubMed1996

Frequent occurrence of p53 mutations in rhabdomyosarcoma and leiomyosarcoma, but not in fibrosarcoma and malignant neural tumors.

We have analyzed soft-tissue sarcomas (STS) molecularly for mutations in the tumor-suppressor gene p53 and immunohisto-chemically for expression of p53 and mdm2 proteins. In this study, tumor samples from 3 groups of soft-tissue sarcomas, i.e., fibrosarcomas, myogenic sarcomas and malignant neural tumors (MNT), were investigated. The methods applied encompass immunohistochemistry on 198 tumor samples using p53 antibodies (DO-1 and DO-7) and an mdm2 antibody (IF-2). Out of these, 100 samples were subjected to non-radioactive PCR-SSCP-sequencing analysis. Immunohistochemical detection rate for p53 (range of 57% to 67%) and for mdm2 proteins (range of 19 to 44%) was similar in all 3 groups. In higher tumor grades, an increased rate of immunopositivity was found for p53 but not for mdm2. Investigation of p53 mutational status revealed 6 mutations in myogenic sarcomas but none in malignant neural tumors or fibrosarcomas, suggesting different roles of p53 in the 3 STS groups. Interestingly, a G-->A transition in codon 245 (a CpG site) was found in 3 myogenic sarcomas. Our results and those of others suggest p53 codon 245 as a mutational hotspot in sarcomas, as recognized in carcinomas.

Base Sequence↗
PubMed1996

Krüppel, a Drosophila segmentation gene, participates in the specification of neurons and glial cells.

We report that the Drosophila segmentation gene Krüppel (Kr) is expressed in neural precursor cells, neurons and glial cells at different stages of neurogenesis and that Kr mutants develop aberrant peripheral (PNS) and central (CNS) nervous systems. Expression derived from a Kr minigene rescues the segmentation defects but these embryos continue to lack most of the neural Kr activity. Phenotypic analysis of the rescued embryos indicates that, in addition to overall effects on the PNS and CNS structure via its segmentation role, Kr expression in the nervous system is functionally required for establishing particular neural and glial fates.

Animals↗
PubMed1996

Germ line and embryonic expression of Fex, a member of the Drosophila F-element retrotransposon family, is mediated by an internal cis-regulatory control region.

The F elements of Drosophila melanogaster belong to the superfamily of long interspersed nucleotide element retrotransposons. To date, F-element transcription has not been detected in flies. Here we describe the isolation of a member of the F-element family, termed Fex, which is transcribed in specific cells of the female and male germ lines and in various tissues during embryogenesis of D. melanogaster. Sequence analysis revealed that this element contains two complete open reading frames coding for a putative nucleic acid-binding protein and a putative reverse transcriptase. Functional analysis of the 5' region, using germ line transformation of Fex-lacZ reporter gene constructs, demonstrates that major aspects of tissue-specific Fex expression are controlled by internal cis-acting elements that lie in the putative coding region of open reading frame 1. These sequences mediate dynamic gene expression in eight expression domains during embryonic and germ line development. The capacity of the cis-regulatory region of the Fex element to mediate such complex expression patterns is unique among members of the long interspersed nucleotide element superfamily of retrotransposons and is reminiscent of regulatory regions of developmental control genes.

Amino Acid Sequence↗
PubMed1995

Molecular and immunohistochemical p53 status in liposarcoma and malignant fibrous histiocytoma: identification of seven new mutations for soft tissue sarcomas.

BACKGROUND: p53 mutations are the most frequently observed tumor-related genetic changes. Mutational analysis concerns mostly carcinomas and is not comprehensive for soft tissue sarcomas. Among soft tissue sarcomas, malignant fibrous histiocytoma (MFH) and liposarcoma represent the most frequent tumor types. Most of the few identified mutations for soft tissue sarcomas are localized in the core domain of p53. A correlation between p53 positive immunoreactivity, missense mutations, and a poor prognosis is generally assumed. However, the character of p53 mutations and their functional importance for the clinical process is still unknown. METHODS: Sixty-two soft tissue sarcoma samples were investigated for the presence of p53 mutations and for p53 immunoreactivity. Exons 4-9 of the p53 gene were amplified from genomic DNA with the polymerase chain reaction. A prescreen for mutations was performed by nonradioactive single strand conformation polymorphism analysis; striking cases were sequenced directly. For an evaluation of the immunohistochemical status, five p53 antibodies were used. RESULTS: In 10 tumor samples 7 new p53 mutations and one polymorphism were identified. Mutations were detected for five liposarcomas (four patients) and four MFHs (three patients). Of the seven mutations, three were missense point mutations, three were deletions, and one was a complex conversion. All mutations but one were localized in the core domain of p53. Of 62 tumor samples, 56% (14 of 32 liposarcomas and 21 of 30 MFHs) were positive for p53 immunostaining. CONCLUSIONS: The mutations identified in the core domain affect codons that are structurally or functionally involved in DNA binding. A relation between p53 positive immunoreactivity and a poor prognosis, but not with an exclusively high tumor grade, is evident. p53 mutations in soft tissue sarcomas have a similar spectrum to those in carcinomas.

Histiocytoma, Benign Fibrous↗
PubMed1995

Activation of posterior gap gene expression in the Drosophila blastoderm.

The process of body prepatterning during Drosophila blastoderm formation relies on the localized activities of zygotic segmentation genes, which are controlled by asymmetrically distributed maternal determinants. The anterior determinant bicoid, a homeodomain transcription factor, forms an anterior-to-posterior concentration gradient. It interacts with the maternal transcription factor hunchback to activate the anterior zygotic patterning genes, including the central gap gene Krüppel (Kr). In contrast, the posterior maternal system does not provide such a decisive transcription factor, but rather prevents the repressor hunchback from acting in the posterior half so that the gap genes giant (gt) and knirps (kni) are activated by an as yet unknown transcription factor. Here we show that caudal, a conserved homeodomain protein that forms a posterior-to-anterior concentration gradient, and the anterior determinant bicoid cooperate to form a partly redundant activator system in the posterior region of the embryo.

Animals↗
PubMed1995

Mesoderm-specific B104 expression in the Drosophila embryo is mediated by internal cis-acting elements of the transposon.

The Drosophila melanogaster genome contains about 100 copies of the B104 transposable element, which is strongly expressed during embryogenesis. Here we show that B104 expression is restricted to the esophageal and amnioproctodeal regions of the embryo and to the developing mesoderm. Mesoderm-specific B104 expression requires the activity of the mesoderm-determining factors twist and snail. Virtually the same expression patterns were observed in Drosophila yakuba, a species that a separated from D. melanogaster by some 15 million years of evolution. We show that B104 expression is directed by internal sequences of the retrotransposon that are capable of acting as a cis-acting regulatory element in front of a heterologous Drosophila promoter. Our findings suggest that retrotransposon insertions can affect the expression patterns of endogenous genes by adding and distributing specific cis-acting control elements throughout the host genome. We therefore propose that transposable elements in addition to reducing the fitness of their hosts may also provide a rich pool of cis-acting sequences that contribute to the long-term evolutionary potential of the population in a beneficial manner.

Amino Acid Sequence↗