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Biomedical subjects

J Rømer

Publications and source records attributed to J Rømer.

32 records · Page 2Linked to original sources
PubMed1995

Neutrophils express tumor necrosis factor-alpha during mouse skin wound healing.

The expression pattern of tumor necrosis factor-alpha (TNF-alpha) mRNA and protein was examined in vivo in experimental mouse skin wounds by in situ hybridization and immunohistochemistry. TNF-alpha mRNA and protein is detected in a distinct layer of mainly neutrophils subadjacent to the would clot. The layer of TNF-alpha-positive cells extends from the margin of the advancing epithelial outgrowth to the opposing one. By in situ hybridization the TNF-alpha mRNA is detectable 12 h after wounding; the signal peaks after 72 h and remains visible up to at least 120 h after wounding. TNF-alpha mRNA could not be detected in the normal skin or in 5-hour-old wounds. Immunohistochemical staining for TNF-alpha and macrophages on adjacent sections confirms that the main part of TNF-alpha-positive cells are polymorphonuclear neutrophils and shows that most of the cells located just beneath the layer of TNF-alpha-positive neutrophils are macrophages with weak TNF-alpha immunoreactivity. The data reported here show that neutrophils serve as an important source of TNF-alpha during healing of mouse skin wounds. We suggest that this specific expression of TNF-alpha is related to the process of re-epithelialization.

Animals↗
PubMed1995

Plasminogen activator inhibitor type 1 in cancer: therapeutic and prognostic implications.

Degradation of the extracellular matrix plays a crucial role in cancer invasion. This degradation is accomplished by the concerted action of several enzyme systems, including generation of the serine protease plasmin by the urokinase pathway of plasminogen activation, different types of collagenases and other metalloproteinases, and other extracellular enzymes. The degradative enzymes are involved also in tissue remodelling under non-malignant conditions, and the main difference appears to be that mechanisms which regulates these processes under normal conditions are defective in cancer. Specific inhibitors have been identified for most of the proteolytic enzymes, e.g. plasminogen activator inhibitors (PAI's) and tissue inhibitors of metalloproteinases (TIMP's). It has been contemplated that these inhibitors counteracted the proteolytic activity of the enzymes, thereby inhibiting extracellular tissue degradation which in turn should prevent tumor cell invasion. This review focuses on plasminogen inhibitor type 1 (PAI-1). It is described that PAI-1 is not produced by the epithelial cancer cell but by the stromal cells in the tumors, suggesting a concerted action between stroma and tumor cells in the processes controlling proteolysis in cancer. The specific localization of PAI-1 to the tumor stroma and in many cases to areas surrounding the tumor vessels has lead us to suggest that PAI-1 serves to protect the tumor stroma from the ongoing uPA-mediated proteolysis. This hypothesis is supported by recent clinical data showing increased levels of PAI-1 in metastases as compared to the primary tumor as well as data demonstrating that high levels of PAI-1 in tumor extracts from breast, lung, gastric and ovarian cancer is associated with a shorter overall survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A cleaved form of the receptor for urokinase-type plasminogen activator in invasive transplanted human and murine tumors.

It was recently found that urokinase-type plasminogen activator (uPA) is involved in the cleavage of its receptor (uPAR) on cultured cells, thereby releasing one of the receptor's 3 domains (the ligand binding domain I) and leaving the 2 others [uPAR(2 + 3)] anchored to the cell surface. With monoclonal antibodies (MAbs) we have now identified human uPAR(2 + 3) in lysates of invasive human MDA-MB-231 mammary carcinomas xenografted into nude mice. The production of peptide antibodies recognizing different domains of murine uPAR made it possible to identify a similar cleaved form of uPAR, murine uPAR(2 + 3), in extracts of primary Lewis lung carcinomas. Cleavage of uPAR also occurs in cultured MDA-MB-231 cells and Lewis lung carcinoma cells. This cleavage is inhibited by anticatalytic antibodies to either human or murine uPA, respectively, indicating that it is catalyzed by either uPA or plasmin generated by uPA. The amount of uPAR(2 + 3) may therefore be directly related to the activity of the uPA system and it is possible that the level of uPAR(2 + 3) in cancer tissue may prove to be a stronger prognostic parameter than the levels of either full-length uPAR or UPA.

Amino Acid Sequence↗
PubMed1994

Expression of uPA and its receptor by both neoplastic and stromal cells during xenograft invasion.

Recent studies have shown that molecules involved in generation and regulation of extracellular proteolytic activity are often expressed by non-malignant stromal cells during human cancer invasion. We have studied the expression of the urokinase-type plasminogen activator and the urokinase-type plasminogen activator cell-surface receptor in xenografts of human MDA-MB-231 mammary carcinoma cells growing invasively in nude mice. Northern analysis showed the presence of both human and mouse urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor mRNA in tumor extracts. By in situ hybridization, mRNA for human urokinase-type plasminogen activator and its receptor was detected in virtually all the cancer cells, while mouse urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor mRNA was expressed by tumor-infiltrating fibroblast-like and macrophage-like cells. In invasive areas the cells expressing the 2 murine mRNAs were either the same or located immediately adjacent to each other. This model system has several advantages for studies of the mechanism by which cancer cells induce or recruit stromal cells to produce molecules involved in proteolysis.

Animals↗
PubMed1994

The receptor for urokinase-type plasminogen activator is expressed by keratinocytes at the leading edge during re-epithelialization of mouse skin wounds.

Expression of urokinase-type plasminogen activator receptor mRNA was examined in vivo in mouse skin wounds by in situ hybridization. Urokinase-type plasminogen activator receptor mRNA was found in keratinocytes at the front of the regenerative epithelial outgrowths at the edge of 12-, 48-, and 96-hour-old wounds. The signal was strongest in the keratinocytes just beginning to move 12 h after wounding. At later time-points the signal was weaker, but still confined to keratinocytes at the wound edges. Using in situ hybridization, no cells expressing urokinase-type plasminogen activator receptor mRNA could be detected in normal epidermis, in normal-looking epidermis adjacent to the wounds, in dermis, in subcutis, or in newly formed granulation tissue. The specificity of the results was supported by the use of antisense RNA from two different non-overlapping cDNA clones and the corresponding sense RNA probes, and by Northern analysis of tissue extracts. Together with previous findings on expression of urokinase-type plasminogen activator and its type 1 inhibitor, the localized and regulated expression of urokinase-type plasminogen activator receptor mRNA during skin wound healing indicates that focal extracellular proteolysis at the cell surface generated by receptor-bound urokinase-type plasminogen activator is implicated in the migration of re-epithelializing keratinocytes.

Animals↗
PubMed1994

The gamma 2 chain of kalinin/laminin 5 is preferentially expressed in invading malignant cells in human cancers.

All known laminin isoforms are cross-shaped heterotrimeric molecules, consisting of one heavy alpha chain and two light beta and gamma chains. Recently, a cDNA encoding a new gamma chain from laminin 5 (also known as kalinin) was sequenced. This chain, named gamma 2, showed extended homology to the classical gamma 1 chain but differed from this by lacking the terminal globular domain. Recent data, indicating an important role of the gamma 2 chain gene in establishing adhesion contacts between epithelial cells and basement membranes, prompted us to investigate whether the gamma 2 chain gene is aberrantly expressed in cancer tissue, and if so whether its localization could provide clues to its possible role in cancer dissemination. Routinely processed tissue specimens from 36 cases of human cancer were investigated, including 16 cases of colon adenocarcinoma, 7 ductal mammary carcinomas, 4 squamous cell carcinomas, 3 malignant melanomas and 6 sarcomas. In situ hybridization for the detection of mRNAs for the gamma 2 chain and for the classical laminin chains alpha 1, beta 1, and gamma 1 was performed using S-35 labeled antisense RNA probes. As positive control of the specificity of the gamma 2 chain mRNA detection, two different anti-sense probes derived from two nonoverlapping cDNA clones were used. Malignant cells were found to express the gamma 2 chain in 29 of the 30 carcinomas studied and the expression was particularly high in cancer cells located at the invasion front. In contrast, mesenchymally derived cancer cells in three different types of sarcomas did not express the gamma 2 chain. In colon cancer there was a clear histological correlation between the expression of gamma 2 chain by cancer cells and their engagement in tumor budding processes. Laminin chains alpha 1, beta 1, and gamma 1 were weakly expressed throughout cancerous areas with no apparent correlation to sites of invasion. The aberrant expression of the gamma 2 chain gene seen in invasively growing cancer cells point to a role of this molecule in establishing focal adhesions of cancer cells to the extracellular matrix during their migration through surrounding normal tissue.

Adenocarcinoma↗
PubMed1993

The nude mouse as an in vivo model for human breast cancer invasion and metastasis.

Human breast cancer xenografts only rarely invade and metastasize in nude mice, and have therefore only had limited use as a model for studying mechanisms involved in breast cancer spreading. However, recent reports describe differences not only between various cell lines but also between strains of immune-deficient mice in terms of providing a model for studies of the invasive and metastatic capability of human breast cancer xenografts. Genetic labelling of human cancer cells with the lacZ gene is described as a specific and highly sensitive method for identification of micrometastases in such a model.

Animals↗
PubMed1992

[Breast cancer and polypeptide growth factors].

Growth factors are crucially involved in the growth of breast cancer cells and in disease progression, both as mediators of endocrine therapy, as co-factors in the development of hormonal resistance, and as regulators of the extracellular proteolysis that precedes invasion and metastasis. Better characterisation and understanding of the mechanisms of action of the various growth factors might open up new possibilities in therapeutic intervention. Thus it would be possible to include in future research the development of synthetic agonists to the inhibitory growth factors, inhibitors of the stimulatory growth factors, and the development of receptor antagonists to block the binding of stimulatory growth factors to their receptors.

Breast Neoplasms↗
PubMed1991

Urokinase receptor mRNA level and gene transcription are strongly and rapidly increased by phorbol myristate acetate in human monocyte-like U937 cells.

We have studied the effect of the tumor promotor phorbol myristate acetate (PMA) on the level of mRNA for the receptor for urokinase-type plasminogen activator (u-PAR) in the human monocyte-like cell line U937. PMA causes an early increase in the u-PAR mRNA level which reaches a maximal 50-fold enhancement after 24 h of treatment. Half-maximal stimulation occurs at approximately 5 nM PMA. The effect is observed only with phorbol esters that also act as tumor promotors. The protein synthesis inhibitor cycloheximide (10 micrograms/ml) also increases the level of u-PAR mRNA. Nuclear run-on experiments show a time-dependent increase in the u-PAR gene transcription rate after exposure of the cells to PMA. The PMA-induced increase in u-PAR mRNA is paralleled by a time-dependent increase in u-PAR protein as detected by cross-linking studies with radiolabeled ligand. We conclude that PMA stimulates transcription of the u-PAR gene in U937 cells, and this is responsible at least in part for the accumulation of the u-PAR mRNA and for the subsequent increase in urokinase-binding capacity.

Blotting, Northern↗
PubMed1991

Urokinase-receptor biosynthesis, mRNA level and gene transcription are increased by transforming growth factor beta 1 in human A549 lung carcinoma cells.

We have compared the cell-specific expression and regulation of the receptor for urokinase-type plasminogen activator (u-PAR) by transforming growth factor beta type 1 (TGF-beta 1) in 10 human cell lines derived from both normal and neoplastic tissues. The basal expression of u-PAR mRNA as well as its response to TGF-beta 1 varied strongly between different cell lines; however, five out of the 10 cell lines responded to TGF-beta 1 by an increase in the u-PAR mRNA level. Among these, A549 cells were selected for a detailed elucidation of the molecular mechanism involved in TGF-beta 1 regulation of u-PAR mRNA expression. TGF-beta 1 caused an early increase in u-PAR mRNA level, with a maximal 15-fold enhancement after 24 h of treatment. This was paralleled by an increase in u-PAR protein as detected by crosslinking studies with radiolabeled ligand, and also resulted in an increase in cell surface plasmin generation. The protein synthesis inhibitor cycloheximide also increased the level of u-PAR mRNA in a time-dependent fashion and when both cycloheximide and TGF-beta 1 were used, an additive effect was seen. Nuclear run-on experiments demonstrated only a moderate (3-fold) increase in the u-PAR gene transcription rate after exposure of the cells to TGF-beta 1 for 3 h compared with a 12-fold increase in the mRNA level. TGF-beta 1 also caused an increase of both u-PA and PAI-1 antigens, while there was no detectable effect on t-PA.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Northern↗
PubMed1991

Differential expression of urokinase-type plasminogen activator and its type-1 inhibitor during healing of mouse skin wounds.

The expression of urokinase-type plasminogen activator (u-PA) and its type-1 inhibitor (PAI-1) was examined in vivo in mouse wounds by in situ hybridization and immunohistochemistry. u-PA mRNA was present in both basal and suprabasal keratinocytes in the regenerative epithelial outgrowths at the edge of the wounds. In the same area, PAI-1 mRNA was only present in the basal keratinocytes. u-PA protein was detected in keratinocytes in several layers of the epithelial outgrowth, whereas PAI-1 protein was confined to the basal keratinocytes and to the area of the basal membrane. The two proteins and their mRNA were not detected in normal epidermis or in normal-looking epidermis adjacent to the wounds. Fibroblast-like cells and fairly large stellate cells (possibly macrophages) in the granulation tissue underneath the wound contained both the two proteins and their mRNA. The large stellate cells, showing a strong hybridization signal for PAI-1 mRNA, were especially abundant at the border between the necrotic wound and the newly formed granulation tissue. The specificity of these results was supported by the use of two different non-overlapping antisense probes, sense mRNA probes, antibody preparations preabsorbed with purified proteins, and Northern analysis of tissue extracts. The localized and regulated expression of u-PA and PAI-1 seen in this study may reflect that plasminogen activation plays a role in the migration of keratinocytes and connective tissue cells during reepithelialization and tissue remodeling in wound healing.

Animals↗