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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When cultured on plastic and treated with transforming growth factor alpha (TGF alpha), human keratinocytes exhibit an increase in proliferation at the colony periphery, apparently as a consequence of enhanced cell migration (Barrandon and Green, 1987). To investigate the effects of TGF alpha on a differentiating stratified squamous epithelium and to begin to examine the molecular basis mediating this influence, we cultured human epidermal cells on a gelled lattice of collagen and fibroblasts, floating on the air-liquid interface. Under these conditions, raft cultures differentiate and exhibit morphological and biochemical features of human skin in vivo (Asselineau et al., 1986; Kopan et al., 1987). When 3-wk-old raft cultures were treated with TGF alpha, basal cells showed a marked increase in cell proliferation. At elevated concentrations of TGF alpha, the organization of cells within the artificial tissue changed and islands of basal cells entered the collagen matrix. Biochemical analysis of the response revealed that type I collagenase and gelatinase were induced by keratinocytes within 12 h after TGF alpha treatment. In contrast, invasion of basal cells into the collagen matrix was not significant until 48-72 h post-treatment, suggesting that collagenase and gelatinase production may be a prerequisite to this phenomenon. These results have important implications for the possible role of TGF alpha in squamous cell carcinoma and tumor invasion.
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PMID:Transforming growth factor alpha induces collagen degradation and cell migration in differentiating human epidermal raft cultures. 166 88

Analysis of the transforming growth factor alpha (TGF alpha) cDNA predicts that the mature TGF alpha polypeptide is cleaved from the extracellular domain of its precursor, which is an integral membrane protein. Furthermore, the cleavage sites for the release of this mitogen are compatible with the participation of an elastaselike protease. We have immunohistochemically localized TGF alpha to the vascular smooth muscle cells in the arterioles. To investigate whether polymorphonuclear (PMN) leukocytic elastase, a blood-borne protease, could process the cell surface TGF alpha, NR6 cells were transfected with the rat TGF alpha cDNA. The cDNA encoded the entire open reading frame, and its expression was under the control of the mouse metallothionein I promoter. A cloned transfectant, termed 1B2, synthesized the TGF alpha precursor in a zinc-inducible manner, and the precursor was localized to the cell surface. Western blot (immunoblot) analysis indicated that treatment of the zinc-induced 1B2 cells with either PMN leukocytic or pancreatic elastase resulted in the release of the mature TGF alpha polypeptide. The released TGF alpha was bioactive, as it was capable of both competing with epidermal growth factor for binding to its receptor and stimulating [3H]thymidine incorporation in the mitogenic assay. Formaldehyde fixation of the 1B2 cells eliminated basal release of TGF alpha but allowed normal processing by both PMN leukocytic and pancreatic elastase to occur. However, human cathepsin G, bovine pancreatic alpha 1-chymotrypsin, collagenase, trypsin, subtilisin, and plasmin failed to release any detectable fragments of the TGF alpha precursor from the fixed cells. The location of TGF alpha in the arterioles and ability of PMN leukocytic elastase to process the membrane-bound TGF alpha precursor suggests a novel role for this elastase at the wound site.
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PMID:Transforming growth factor alpha in arterioles: cell surface processing of its precursor by elastases. 220 95

The aim of the study was to determine the binding characteristics of the epidermal growth factor (EGF) receptor in isolated human endometrial glands and stromal cells in culture. Stromal cells and glands were obtained from endometrial tissue by collagenase dispersion followed by sieve filtration. They were plated into 24-well multiwell plates in Ham's F10 medium supplemented with 5% fetal calf serum and used at 70-80% confluence. Scatchard analysis revealed a single class of high-affinity binding sites in both cell types with apparent dissociation constants of 1.17 +/- 0.6 (n = 15) and 1.20 +/- 0.3 (n = 8) nmol 1-1 for stromal cells and glands, respectively. The concentration of receptors was higher in stromal cells than in glands, 719 +/- 377 (n = 16) and 310 +/- 177 (n = 8) fmol mg-1 protein, respectively. Epidermal growth factor labelled with 125I was displaced from the receptor by EGF and transforming growth factor alpha, but not insulin, insulin-like growth factor, fibroblast growth factor, or platelet-derived growth factor. Binding was shown to be dependent on time and temperature. Downregulation of the receptor was demonstrated by preincubating cells with 5 nmol EGF I-1, which reduced receptor concentrations by 75%. 12-O-Tetradecanoylphorbol-13-acetate decreased the affinity of the receptor for EGF changing the dissociation constant from 1.8 to 3.9 nmol l-1. A suitable system for investigating the regulation of this receptor in human endometrium was established.
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PMID:Characterization of epidermal growth factor receptor in human endometrial cells in culture. 793 77

A tissue culture system for rat prostatic epithelial cells was developed, and the effect of epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and transforming growth factor beta 1 (TGF-beta 1) on these cells was evaluated. The primary culture was prepared by DNAse/collagenase dissociation of minced ventral prostates. Cells were initially plated in RPMI-1640 medium containing 10% fetal bovine serum to allow the preferential attachment of stromal cells. Twenty-four hours later, the unattached epithelial cells were replated in WAJC-404 medium supplemented with insulin (5 micrograms/ml), transferrin (5 micrograms/ml), and selenious acid (5 ng/ml). Bovine pituitary extract (BPE) (30 micrograms/ml), EGF (10 ng/ml), and TGF-beta 1 (0, 0.1, and 1.0 ng/ml) were added either alone or in combination according to experimental requirements. The rate of cell proliferation was assessed by counting the total cell number and by [3H]thymidine incorporation. Prostatic epithelial cells exhibited a bell-shaped growth curve in a span of 7-8 days, with a growth peak at day 3 or 4 of culture. Treatment of cells with EGF or TGF-alpha resulted in a concentration-dependent increase in cell growth, whereas addition of TGF-beta 1 into the culture resulted in an inhibition of cell proliferation that could be reversed with increasing concentrations of EGF. Cell death was assessed using the terminal deoxynucleotidyl transferase (TdT)-mediated immunoperoxidase-digoxigenin nick end labeling technique and the trypan blue exclusion test. Epithelial cells cultured in media containing EGF had the lowest incidence of cell death. Cells cultured in the absence of EGF demonstrated a marked increase in cells undergoing cell death. The addition of TGF-beta 1 into the EGF-depleted medium caused a further increase of cell death. These results indicated that cell proliferation and cell death in rat prostatic epithelial cells in culture could be modulated by EGF and TGF-beta 1. The former stimulated cell proliferation and prevented cell death, whereas the latter inhibited proliferation in the presence or absence of EGF and induced cell death.
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PMID:Effect of TGF-beta 1, TGF-alpha, and EGF on cell proliferation and cell death in rat ventral prostatic epithelial cells in culture. 886 96

The role of transforming growth factor alpha (TGFalpha) and prostaglandins (PGs) in the preferential growth of preneoplastic liver cells was studied. Rats received the genotoxic hepatocarcinogen N-nitrosomorpholine (NNM); placental glutathione S-transferase (GSTp) was used as a marker to identify preneoplastic foci. Preneoplastic foci expressing TGFalpha (TGFalpha(+)) grew more rapidly than TGFalpha negative (TGFalpha(-)) ones. Almost all tumours studied were positive for TGFalpha. The key enzymes of prostaglandin synthesis, cyclooxygenase I (Cox-1) and II (Cox-2), were present in all unaltered and preneoplastic cells and tended to decrease in the later stages of hepatocarcinogenesis. Immunostaining revealed that cultures of hepatocytes, isolated from NNM-treated livers by collagenase perfusion, contained 1-2% GSTp-positive (GSTp(+)) and 9% TGFalpha(+) hepatocytes; 0.6% of the cells were GSTp(+)/TGFalpha(+). Cox-1 and Cox-2 were present in all cells. DNA replication was almost exclusively associated with expression of TGFalpha. GSTp(+) hepatocytes showed a 3- to 4-fold higher probability of TGFalpha expression and of DNA synthesis than GSTp-negative (GSTp(-)) cells. PGE(2) or PGF(2alpha) increased expression of TGFalpha and DNA replication in GSTp(-) cells but not in GSTp(+) cells. PGA(2) and PGJ(2) decreased DNA synthesis in TGFalpha(+) cells without an obvious effect on the intracellular levels of TGFalpha. The Cox-2 inhibitor SC236 suppressed DNA replication preferentially in GSTp(+) cells; this inhibition was reversed by PGE(2)/F(2alpha). Indomethacin had no effect. These results suggest the following conclusions. (i) Growth regulation of preneoplastic GSTp(+) cells in culture exhibits distinct differences from GSTp(-) cells and elevated expression of TGFalpha contributes to their growth advantage. (ii) TGFalpha renders preneoplastic hepatocytes sensitive to suppression of DNA synthesis by PGA(2)/J(2). (iii) SC236, a Cox-2 inhibitor, may have preventive value in hepatocarcinogenesis.
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PMID:Role of transforming growth factor alpha and prostaglandins in preferential growth of preneoplastic rat hepatocytes. 1147 Jul 56

For growth stimulation of liver cells by hepatocyte growth factor (HGF) or transforming growth factor alpha (TGFalpha) via receptor tyrosine kinases, c-fos/c-jun has been considered a point of intersection for cross-talk between the different signal transduction pathways. Recent evidence strongly implicates translocation of pro-TGFalpha into the nucleus as an important step preceding the initiation of hepatic DNA synthesis. We asked whether an active c-jun is required for the nuclear translocation of pro-TGFalpha and its stimulatory effect on DNA synthesis. For this purpose we used mice with c-jun inactivated post partum in hepatocytes by the Cre-loxP recombination system (c-jun(Deltaliver)). Nuclear fractions from control and c-jun(Deltaliver) mouse livers contained TGFalpha as pro-form of 17 kDa and the epidermal growth factor receptor (erbb-1) with molecular weights of 170 and 150 kDa (truncated form). Hepatocytes were isolated by collagenase perfusion and cultivated. A lack of c-jun did not alter the apoptotic activity but significantly suppressed DNA synthesis in the cultured hepatocytes. In control and c-jun(Deltaliver) cells DNA synthesis was almost always associated with nuclear presence of pro-TGFalpha. 76.5 +/- 6.8% of hepatocytes with pro-TGFalpha positive nuclei and only 4.52 +/- 1.31% of hepatocytes with negative nuclei exhibited DNA replication. About 85% of the pro-TGFalpha positive nuclei also contained erbb-1. Treatment of cultures with mature TGFalpha or HGF elevated the frequency of pro-TGFalpha positive nuclei replicating DNA; HGF and TGFalpha-induced nuclear pro-TGFalpha and DNA synthesis significantly more in c-jun(Deltaliver) than in control hepatocytes. These results suggest that (i) a lack of c-jun suppresses basal rates of DNA replication in hepatocytes; (ii) c-jun deficient hepatocytes show a pronounced growth response towards HGF or TGFalpha; (iii) nuclear translocation of pro-TGFalpha together with erbb-1 and its association with DNA synthesis are independent of c-jun.
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PMID:Induction of DNA synthesis in primary mouse hepatocytes is associated with nuclear pro-transforming growth factor alpha and erbb-1 and is independent of c-jun. 1277 Oct 26

The pro-peptide of transforming growth factor alpha (proTGFalpha) was recently found in hepatocyte nuclei preparing for DNA replication, which suggests a role of nuclear proTGFalpha for mitogenic signalling. This study investigates whether the nuclear occurrence of the pro-peptide is involved in the altered growth regulation of (pre)malignant hepatocytes. In human hepatocarcinogenesis, the incidence of proTGFalpha-positive and replicating nuclei gradually increased from normal liver, to dysplastic nodules, to hepatocellular carcinoma. ProTGFalpha-positive nuclei almost always were in DNA synthesis. Also, in rat hepatocarcinogenesis, proTGFalpha-positive nuclei occurred in (pre)malignant hepatocytes at significantly higher incidences than in unaltered hepatocytes. For functional studies unaltered (GSTp(-)) and premalignant (GSTp(+)) rat hepatocytes were isolated by collagenase perfusion and cultivated. Again, DNA synthesis occurred almost exclusively in proTGFalpha-positive nuclei. GSTp(+) hepatocytes showed an approximately 3-fold higher frequency of proTGFalpha-positive nuclei and DNA replication than GSTp(-) cells. Treatment of cultures with the mitogen cyproterone acetate (CPA) elevated the incidence of proTGFalpha-positive nuclei and DNA synthesis in parallel. Conversely, transforming growth factor beta1 (TGFbeta1) lowered both. These effects of CPA and TGFbeta1 were significantly more pronounced in GSTp(+) than in GSTp(-) hepatocytes. In conclusion, nuclear translocation of proTGFalpha increases in the course of hepatocarcinogenesis and appears to be involved in the inherent growth advantage of (pre)malignant hepatocytes.
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PMID:Inherent growth advantage of (pre)malignant hepatocytes associated with nuclear translocation of pro-transforming growth factor alpha. 1553 11

Even today prematurity is the major cause of perinatal mortality. Prematurity has multiple causes. There is a growing body of evidence supporting the association between silent intrauterine infection and preterm birth. Bacterial products may activate macrophages ubiquitous present in the decidua, placenta and fetal membranes. These cells after activation secrete a large variety of mediators including tumour necrosis factor alpha (TNFalpha) and interleukin (IL)-1. Besides these cytokines IL-2, IL-3, IL-4, IL-6, IL-8, IL-10, epidermal growth factor, granulocyte-colony stimulating factor and transforming growth factor beta have been identified in intrauterine tissues and in the amniotic fluid. The majority of these substances (TNFalpha, IL-1, IL-2, IL-3, IL-6) can stimulate the prostaglandin-biosynthesis by intrauterine tissues (amnion, chorion, decidua), some of them have antiinflammatory effects (IL-10, transforming growth factor alpha). These effects are mediated by receptors on the target cells; specific receptor antagonists (for example for IL-1) were found in high concentrations in amniotic fluid during normal pregnancy. This cytokine network is in a sensitive balance and probably associated with an uncomplicated course of pregnancy. Systemic or localized infections as well as tissue injury initiate the induction of the prostaglandin synthesis cascade thus leading to pregnancy loss via augmented cytokine secretion. Furthermore, cytokines may be involved in the regulation of preterm and term cervical ripening. The changes in mechanical properties of the cervix are associated with a reduction of collagen content and alterations in the glycosaminoglycan pattern within the cervical extracellular matrix. IL-1 can stimulate the synthesis of collagenases, and IL-8 may play an important role in the regulation of the invasion of neutrophilic granulocytes into the cervical stroma with subsequent degranulation and release of proteases. The cytokine-stimulated collagenase production in the fetal membranes is responsible for the reduction of their tensile strength and may be associated with rupture of the membranes. The cytokine network seems to be a sensitive regulation system. Disturbances of its balance by environmental (e.g. infection) or intrauterine influences (e. g. extension by the fetus) may lead to termination of pregnancy.
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PMID:[The role of cytokines in the induction of labor, cervical ripening and rupture of the fetal membranes]. 1676 18

Bone metastasis is mediated by complex interactions between tumor cells and resident stromal cells in the bone microenvironment. The functions of metalloproteinases in organ-specific metastasis remain poorly defined despite their well-appreciated role in matrix degradation and tumor invasion. Here, we show a mechanism whereby two distinct metalloproteinases, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS1) and matrix metalloproteinase-1 (MMP1), orchestrate a paracrine signaling cascade to modulate the bone microenvironment in favor of osteoclastogenesis and bone metastasis. Proteolytic release of membrane-bound epidermal growth factor (EGF)-like growth factors, including Amphiregulin (AREG), heparin-binding EGF (HB-EGF), and transforming growth factor alpha (TGFalpha) from tumor cells suppress the expression of osteoprotegerin (OPG) in osteoblasts and subsequently potentiate osteoclast differentiation. EGF receptor (EGFR) inhibitors block osteolytic bone metastasis by targeting EGFR signaling in bone stromal cells. Furthermore, elevated MMP1 and ADAMTS1 expression is associated with increased risk of bone metastasis in breast cancer patients. This study established MMP1 and ADAMTS1 in tumor cells, as well as EGFR signaling in osteoblasts, as promising therapeutic targets for inhibiting bone metastasis of breast cancer.
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PMID:ADAMTS1 and MMP1 proteolytically engage EGF-like ligands in an osteolytic signaling cascade for bone metastasis. 1975 60