Biomedical subjects

P Herrlich

Publications and source records attributed to P Herrlich.

At least 109 records · Page 6Linked to original sources

PubMed1993

Differential expression of CD44 splice variants in intestinal- and diffuse-type human gastric carcinomas and normal gastric mucosa.

Immunohistochemical screening of gastric adenocarcinomas from 42 different patients revealed variant CD44 expression in all specimens tested. Adenocarcinomas of the intestinal type were strongly positive for epitopes encoded by variant exons v5 and v6, whereas diffuse-type adenocarcinomas predominantly expressed only exon v5. Normal stomach mucosa was stained by an exon v5-specific monoclonal antibody within the foveolar proliferation zone and on mucoid surface epithelium. Areas of intestinal metaplasia reacted positively with monoclonal antibodies specific for exons v5 and v6. Analysis of RNA expression revealed dramatic differences between normal mucosa and adenocarcinomas. Whereas in normal epithelium only two CD44 variant RNAs containing exons v5 and/or v6 could be detected, intestinal-type tumors yielded a much more complex pattern of amplification products which hybridized to exons v5 and v6. A similar complex expression pattern of CD44 variants was observed in three cell lines established from intestinal-type tumors. In a sample of a diffuse-type tumor, expression of exon v5, but not v6, could be detected, confirming the data obtained with immunohistochemistry. These differences in variant exon v6 expression observed between diffuse-type and intestinal-type stomach adenocarcinomas establish variant CD44-specific antibodies as a tool in gastric cancer diagnosis and also support the theory of different origins for these tumor types.

Adenocarcinoma↗

PubMed1993

Interleukin 1 induction of the c-jun promoter.

Interleukin 1 (IL-1) induces pleiotropic effects in many cell types during inflammation and immunity. We have recently shown how the IL-1 signal is transmitted to the nucleus: In T cells and in pituitary cells, IL-1 induced genes via activation of the nuclear factor AP-1. We now demonstrate how IL-1 activates the AP-1 factor in liver cells, which are a major target for IL-1 during the acute phase response in vivo. IL-1 induced gene transcription of both AP-1 components, c-jun and c-fos. IL-1 also increased the stability of c-jun mRNA. We define two enhancer sites in the jun promoter that are required for induction by IL-1. Although the binding sites share some similarity with the AP-1 binding site, the nuclear factors binding the jun motifs are not composed of Jun or Fos proteins. Thus these data identify two binding proteins that serve as one of the first nuclear targets for IL-1 signal transduction.

Base Sequence↗

PubMed1993

Activated human lymphocytes and aggressive non-Hodgkin's lymphomas express a homologue of the rat metastasis-associated variant of CD44.

A recently described splice variant of CD44 expressed in metastasizing cell lines of rat tumors, has been shown to confer metastatic potential to nonmetastasizing rat pancreatic carcinoma and sarcoma cell lines. Using antibodies raised against a bacterial fusion protein encoded by variant CD44 sequences, we have explored the expression of variant CD44 glycoproteins on human lymphoid cells and tissues and on non-Hodgkin's lymphomas. Normal lymphohematopoietic cells express barely detectable low levels of variant CD44 glycoproteins, whereas T lymphocytes, upon activation by mitogen or antigen, transiently upregulate expression of specific CD44 variant glycoproteins. The reaction pattern of various antibodies indicates that these CD44 variants contain the domain encoded by exon v6, which is part of the variant that in the rat confers metastatic capability. It is interesting that overexpression of v6 was also found in several aggressive, but not low-grade, non-Hodgkin's lymphomas.

Animals↗

PubMed1993

A link between ras and metastatic behavior of tumor cells: ras induces CD44 promoter activity and leads to low-level expression of metastasis-specific variants of CD44 in CREF cells.

The activated oncogene c-Ha-ras induces expression of the surface glycoprotein CD44 in cloned rat embryonic fibroblasts (CREF). Induction is transcriptional as shown by transient cotransfections of c-Ha-ras expression constructs and CD44 promoter reporter gene constructs and depends on the presence of an AP-1 binding site at position -110. Increased transcript levels for the standard isoform of CD44 (CD44s) are accompanied by the appearance of alternatively spliced RNAs and the synthesis of variants of CD44 (CD44v). These CD44v molecules differ from the standard type by the addition of sequences in the extracellular portion of the molecules. The occurrence of CD44v molecules in CREF cells upon induction of the CD44 promoter is probably due to leakiness of the splice control in these cells since stable transfection with c-Ha-ras does not alter the CD44v/total CD44 ratio. Upon ras overexpression, however, using an inducible mouse mammary tumor virus-ras construct, a transient increase of CD44v/total CD44 ratio of 3-4 has been determined suggesting that a burst of ras expression, in the genetic background of CREF cells, influences both promoter activity and splice control or accuracy. The expression of CD44v proteins is responsible for the metastatic potential in a variety of tumors (U. Günthert et al., Cell, 65: 13-24, 1991). Also in CREF cells expression of CD44v correlates with metastatic behavior, ras-transfected CREF cells are not only fully transformed but also give rise to metastatic spread as measured in the spontaneous metastasis assay. The adenoviral oncogene E1A counteracts ras-induced promoter function and, consequently, inhibits metastatic behavior without extinguishing transformation.

Animals↗

PubMed1993

UV irradiation-induced interleukin-1 and basic fibroblast growth factor synthesis and release mediate part of the UV response.

UV irradiated cells release into the culture medium factors that induce, when given to nonirradiated cells, the transcription of several UV-inducible genes (collagenase I, human immunodeficiency virus type 1, metallothionein IIA). We identify here the active factors released from UV-treated HeLa cells, as interleukin 1 alpha and basic fibroblast growth factor. UV irradiation leads to increased mRNA levels for both factors and to their enhanced synthesis. Experiments with the drug suramin, which inhibits growth factor-growth factor receptor interactions and with antibodies directed against interleukin 1 alpha and basic fibroblast growth factor, suggest that growth factors do not only transduce the UV-induced signal to nonirradiated cells but act on the producer cell thus establishing an obligatory growth factor loop for at least part of the UV response.

Antibodies↗

PubMed1993

The two major CD44 proteins expressed on a metastatic rat tumor cell line are derived from different splice variants: each one individually suffices to confer metastatic behavior.

The metastatic pancreas carcinoma cell line BSp73ASML produces a variety of different splice variants of the transmembrane glycoprotein CD44. The NH2-terminal portions are identical and heavily glycosylated. The variant sequences are inserted just outside the transmembrane region of the molecules. The two most abundant variants have 162 and 85 extra amino acids, respectively. When individually expressed, these suffice to establish metastatic properties in the nonmetastatic tumor cell line BSp73AS, as assayed by the spontaneous metastasis protocol.

Adenocarcinoma↗

PubMed1993

Splicing choice from ten variant exons establishes CD44 variability.

The enormous heterogeneity of the surface protein designated CD44 is in part due to posttranslational modification, and in part due to differential splicing. Alternative splicing occurs within one particular region encoding the extracellular portion of the protein. Comparison of various cDNA clones with different 'inserts' in this variable region with sequences of genomic clones from the mouse has revealed the existence of at least ten exons from which sequences are chosen by alternative splicing. Various combinations of these exons account for the tremendous heterogeneity of CD44 molecules expressed in different tissues, and in progressing tumor cells. The existence of different isoforms of CD44 suggests a broad spectrum of yet unknown physiologic functions.

Amino Acid Sequence↗

PubMed1993

Prevention of tumor metastasis formation by anti-variant CD44.

A splice variant of CD44 (CD44v) originally discovered on metastases of a rat pancreatic adenocarcinoma (BSp73ASML) has been shown by transfection to confer metastatic behavior to nonmetastatic tumor cells (Günthert U., M. Hofmann, W. Rudy, S. Reber, M. Zöller, I. Haussmann, S. Matzku, A. Wenzel, H. Ponta, and P. Herrlich. 1991. Cell. 65:13). A monoclonal antibody (mAb), 1.1ASML, to the metastasis-specific domain of the CD44v molecule retards growth of lymph node and lung metastases of the metastatic tumor line BSp73ASML, and can efficiently prevent formation of metastases by the transfected line. The antibody is only effective when given before lymph node colonization. Anti-CD44v does not downregulate the expression of CD44v, and prevention of metastatic growth by anti-CD44v is not due to activation of any kind of immune defense. We suggest that the mAb interferes with proliferation of metastasizing tumor cells in the draining lymph node, most probably by blocking a ligand interaction. The interference with metastatic spread will greatly facilitate the exploration of the function of CD44v and, in particular, may also open new strategies for the therapy of human metastases.

Animals↗

PubMed1993

Heterodimer formation of cJun and ATF-2 is responsible for induction of c-jun by the 243 amino acid adenovirus E1A protein.

The adenovirus E1A proteins differentially regulate AP-1-responsive genes. Collagenase and stromelysin are repressed by E1A, whereas the expression of c-jun is elevated. Inhibition of collagenase has been found to be exerted through the consensus AP-1 binding site TGAGTCA. Here we show that the distal AP-1 binding site in the c-jun promoter, the jun2TRE (TTACCTCA), is the decisive element of this promoter in mediating the positive response to the 243 amino acid E1A product. In vitro binding studies revealed that, in contrast to the consensus AP-1 site which is preferentially targeted by dimers composed of the Jun and Fos families, the jun2TRE binds heterodimers composed of cJun and ATF-2(-like) proteins. Since stimulation of c-jun transcription is a function of the transforming domain of E1A encoded by conserved region 1, cJun--ATF-2 may be one of the effector factors involved in transformation. The data further suggest that E1A can distinguish between cJun--cJun and cJun--ATF-2 in imposing opposite states of activity.

3T3 Cells↗

PubMed1993

UV-induced activation of AP-1 involves obligatory extranuclear steps including Raf-1 kinase.

Irradiation of cells with ultraviolet light (UV) leads to modifications of c-Jun resembling those elicited by phorbol esters or oncogenes, and to enhanced transcription of AP-1-dependent genes. The UV-induced signal also triggers activation of Raf-1 and MAP-2 kinases. A dominant-negative Raf-1 kinase mutant strongly interferes with both phorbol ester and UV-induced AP-1 activation, indicating obligatory involvement of identical components in cytoplasmic signal transduction. Thus, from a presumably nuclear site of energy absorption, a signal needs to be transmitted to the cytoplasm in order to achieve activation of a nuclear transcription factor. Further, signals elicited from different primary sites merge prior to or at the level of activation of Raf-1 kinase.

Base Sequence↗

PubMed1993

Adenovirus E1A negatively and positively modulates transcription of AP-1 dependent genes by dimer-specific regulation of the DNA binding and transactivation activities of Jun.

Adenovirus E1A proteins inhibit expression of the collagenase gene but activate expression of the c-jun gene. Both effects are mediated by TPA-responsive elements (TREs), the binding sites for members of the AP-1 transcription factor family. By a process that is independent of the retinoblastoma gene product, E1A distinguishes between different AP-1 factors: in vivo binding of Jun/Jun homodimers and Jun/Fos heterodimers to the collagenase TRE is totally blocked by E1A while, in contrast, there is no inhibition of Jun/ATF-2 binding to the TRE sequences in the c-jun promoter. Altered phosphorylation of the DNA binding domain of cJun is not involved in the inhibition of cJun/cJun and cJun/cFos binding. E1A does, however, cause hyperphosphorylation of the transactivation domain of cJun, which is likely to be responsible for the enhanced c-jun transcription by E1A mediated through cJun/ATF-2 heterodimers.

Activating Transcription Factors↗

PubMed1993

Cross-coupling of the NF-kappa B p65 and Fos/Jun transcription factors produces potentiated biological function.

NF-kappa B and AP-1 represent distinct mammalian transcription factors that target unique DNA enhancer elements. The heterodimeric NF-kappa B complex is typically composed of two DNA binding subunits, NF-kappa B p50 and NF-kappa B p65, which share structural homology with the c-rel proto-oncogene product. Similarly, the AP-1 transcription factor complex is comprised of dimers of the c-fos and c-jun proto-oncogene products or of closely related proteins. We now demonstrate that the bZIP regions of c-Fos and c-Jun are capable of physically interacting with NF-kappa B p65 through the Rel homology domain. This complex of NF-kappa B p65 and Jun or Fos exhibits enhanced DNA binding and biological function via both the kappa B and AP-1 response elements including synergistic activation of the 5' long terminal repeat of the human immunodeficiency virus type 1. These findings support a combinatorial mechanism of gene regulation involving the unexpected cross-coupling of two different classes of transcription factors to form novel protein complexes exhibiting potentiated biological activity.

3T3 Cells↗

PubMed1993

CD44 splice variants: metastases meet lymphocytes.

Recent discoveries of surface proteins involved in tumor metastasis formation have revived an old hypothesis that tumor cells may acquire, and use for their metastatic spreading, properties which lymphoid cells had developed to defend the organism against foreign antigens. Splice variants of CD44 and integrins are expressed on metastasizing tumor cells and also on leukocytes at defined stages of their differentiation. Expression and function appear to be essential not only for the generation of an immune response but also for the establishment of metastatic tumor colonies.

Alternative Splicing↗

PubMed1993

Expression of CD44 isoforms carrying metastasis-associated sequences in newborn and adult rats.

Expression of a splice variant of CD44, recognised by the monoclonal antibody (Mab) 1.1ASML, confers metastatic potential to non-metastasising tumour cells (Cell 1991, 65, 13-24). To explore whether the metastasis-associated variant of CD44 (CD44v) is expressed under physiological conditions, tissues of newborn and adult rats were stained with the Mab 1.1ASML. The 1.1ASML epitope is, indeed, expressed on the basal layer of the epidermis and the hair follicles as well as on cryptic epithelia in the gut. In addition, ductal epithelia of the pancreatic gland of newborn rats express CD44v. This pattern of expression differs from that of standard lymphocyte CD44 (CD44s). The anti-CD44s mAB Ox50 predominantly stains connective tissue. Although different variants of CD44 may express the epitope recognised by 1.1ASML, cells expressing CD44v share properties with metastasising tumour cells: the stage of proliferation and a restricted degree of mobility. Thus, during metastatic progression tumour cells may reactivate the expression of gene segments which serve highly specialised functions in embryonic and adult tissues.

Aging↗

PubMed1993

A human homologue of the rat metastasis-associated variant of CD44 is expressed in colorectal carcinomas and adenomatous polyps.

A recently described splice variant of CD44 expressed in metastasizing cell lines of rat tumors has been shown to confer metastatic potential to a non-metastasizing rat pancreatic carcinoma cell line and to non-metastasizing sarcoma cells. Homologues of this variant as well as several other CD44 splice variants are also expressed at the RNA level in human carcinoma cell lines from lung, breast, and colon, and in immortalized keratinocytes. Using antibodies raised against a bacterial fusion protein encoded by variant CD44 sequences, we studied the expression of variant CD44 glycoproteins in normal human tissues and in colorectal neoplasia. Expression of CD44 variant proteins in normal human tissues was readily found on several epithelial tissues including the squamous epithelia of the epidermis, tonsils, and pharynx, and the glandular epithelium of the pancreatic ducts, but was largely absent from other epithelia and from most non-epithelial cells and tissues. In human colorectal neoplasia CD44 variant proteins, including homologues of those which confer metastatic ability to rat tumors, were found on all invasive carcinomas and carcinoma metastases. Interestingly, focal expression was also observed in adenomatous polyps, expression being related to areas of dysplasia. The distribution of the CD44 variants in human tissues suggests that they play a role in a few restricted differentiation pathways and that in colorectal tumors one of these pathways has been reactivated. The finding that metastasis-related variants are already expressed at a relatively early stage in colorectal carcinogenesis and tumor progression, i.e., in adenomatous polyps, suggests the existence of a yet unknown selective advantage linked to CD44 variant expression. The continued expression in metastases would be compatible with a role in the metastatic process.

Antibodies, Monoclonal↗

PubMed1993

Overexpression of c-fos increases recombination frequency in human osteosarcoma cells.

We have shown previously that overexpression of c-Ha-ras, v-mos or c-fos increases the spontaneous level of chromosomal aberrations and gene mutations in NIH 3T3 cells, and that reduction of the Fos protein level inhibits aberration induction by c-Ha-ras and v-mos and also by irradiation with ultraviolet light (van den Berg et al., Mol. Carcinogenesis, 4, 460-466). In order to examine whether fos is also involved in DNA recombination, thymidine kinase (tk) deficient human osteosarcoma cells containing two versions of the herpes simplex virus tk gene inactivated by base insertion were either transiently or stably transfected with various fos expression plasmids. The frequency of tk+ revertants was significantly enhanced both upon transient transfection with RSV-promoter-fos gene constructs and by stimulation of Fos synthesis in stably transfected cells harbouring an inducible metallothionein promoter-fos construct. No such increases were observed in cells transfected with plasmids containing a truncated version of c-fos. The data indicate that c-fos is involved in generating various types of genetic changes including homologous recombination; a role of c-fos in genetic instability may contribute to its action in tumor promotion and progression.

Animals↗

PubMed1993

CD44 splice variants: expression during lymphocyte activation and tumor progression.

A recently described splice variant of CD44 has been shown to confer metastatic potential to non-metastasizing rat pancreatic carcinoma and sarcoma cell lines. Using antibodies raised against a bacterial fusion protein encoded by variant CD44 sequences, we have explored the expression of variant CD44 glycoproteins in human lymphoid cells and tissues, in non-Hodgkin's lymphomas, and in colorectal neoplasia. Normal lymphohematopoietic cells express barely detectable low levels of variant CD44 glycoproteins, while T lymphocytes, upon activation by mitogen or antigen, transiently upregulate expression of specific CD44 variant glycoproteins. The reaction pattern of various antibodies indicates that these CD44 variants contain the domain encoded by exon v6, which is part of the variant that in the rat confers metastatic capability. Interestingly, overexpression of v6 was also found in several aggressive, but not in low-grade, non-Hodgkin's lymphomas (NHL). In human colorectal neoplasia we also observed strong overexpression of CD44 splice variants in all invasive carcinomas and carcinoma metastasis. Interestingly, focal expression was already observed in adenomatous polyps, expression being related to areas of dysplasia. The findings establish CD44 variants as tumor progression markers in colorectal cancer.

Alternative Splicing↗

PubMed1992

Participation in normal immune responses of a metastasis-inducing splice variant of CD44.

A variant of the glycoprotein CD44 (CD44v) that shares sequences with variants causally involved in metastasis formation is transiently expressed on B and T lymphocytes and macrophages after antigenic stimulation and in the postnatal period. Antibodies to the variant hinder in vivo activation of both B and T cells. The observation that a protein domain that is expressed on CD44 and required for the lymphatic spread of tumor cells can catalyze an essential step in the process of lymphocyte activation supports the idea that metastasizing tumor cells mimic lymphocyte behavior.

Animals↗