Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

Normal and premalignant mouse mammary epithelial cells can be prepared in high yields by collagenase dissociation of minced glands followed by a brief, differential centrifugation to remove contaminating fibroblasts and fat cells. The major difficulties in preparing pure cultures in quantity are 1) incomplete dissociation of gland material, and 2) cell death during enzymatic digestion. These problems are eliminated by careful selection of collagenases for dissociation. Normal and premalignant mammary epithelial cells are morphologically indistinguishable from malignant mouse mammary epithelial cells in primary monolayer cultures. In addition, the growth rates and saturation densities achieved by normal mammary epithelial cells are indistinguishable from those of malignant mammary epithelial cells in primary culture. In both cases, a monolayer of cells is preserved with no evidence of focal overgrowth. Malignant adenocarcinoma mammary cells can however be distinguished from normal mammary epithelial cells by virtue of differences in their surface interactions with concanavalin A. A hemadsorption assay using Con-A-coated erythrocytes was the most sensitive indicator for these differences. In hemadsorption assays malignant mammary epithelial cells were half-maximally reactive with 2.5 mug/ml concanavalin A, while normal cells were completely unreactive even at concanavalin A concentrations five-times higher. Premalignant mammary epithelial cells were as reactive as malignant mammary epithelial cells in the hemadsorption assays. Hemadsorption of malignant cells was observed in primary and secondary cultures of epithelium as well as in cell lines. Malignant cells forming mammary adenocarcinomas were as highly reactive as malignant cells forming scirrhous carcinomas. Malignant cells not releasing mammary tumor virus (MuMTV) were as reactive as cells releasing that virus. Adsorption of concanavalin-A-coated erythrocytes to normal mammary epithelial cells could be induced by brief treatment of cell monolayers with hyaluronidase. Exposure of active sites was not affected with either trypsin or collagenase. Our results show that while the growth of malignant cells does not serve to distinguish them from normal cells in monolayer culture, surface changes do exist which can be identified by differences in concanavalin A reactivity. Since the earliest transformants identifiable in vivo (premalignant) have undergone conversion of the surface marker, concanavalin-A-mediated hemadsorption provides a sensitive measure for mammary epithelial cell transformants in vitro.
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PMID:Markers to distinguish normal and neoplastic mammary epithelial cells in vitro: comparison of saturation density, morphology and concanavalin A reactivity. 18 59

Preneoplastic mammary nodule lines D1, D2, and C4 were enzymatically dissociated with collagenase, hyaluronidase, and pronase or with only collagenase and hyaluronidase to produce high yields of viable single cells; 10(5) cells were injected into the cleared mammary fat pads of syngeneic BALB/cCrgl mice. In 11 experiments involving three different preneoplastic nodule lines with different tumor potentials, all dissociated nodule cell lines showed a marked increase in tumorigenicity as compared to the same tissues transplanted as 1-mm3 pieces. The results could not be explained on the basis of differences between the amounts of cells transplanted in the two procedures. In a second series of experiments, normal mammary cells from virgin, pregnant, or lactating mice were mixed in different ratios with 10(5) nodule cells and injected into the mammary fat pads. The presence of normal cells reversed the marked increase in the tumorigenicity of enzymatically dissociated nodule cells to a level equal to or less than the tumorigenicity of control transplants (1-mm3 pieces). The growth of 10(5) mammary tumor cells was not inhibited when tumor cells were mixed with 3 x 10(5) normal cells and transplanted into the mammary fat pads. These results showed that enzymatic dissociation can lead to an increase in tumor potential of preneoplastic mammary nodule lines, and they supported the hypothesis that nodule cells, but not neoplastic cells, are sensitive to the growth-inhibitory effects of normal mammary cells.
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PMID:Enhancement of the tumorigenicity of preneoplastic mammary nodule lines by enzymatic dissociation. 20 61

Inapparent nodule-transformed cells were recovered from morphologically normal mammary tissue from virgin female BALB/cfC3H/Crgl (mouse mammary tumor-positive) mice before the appearance of hyperplastic alveolar nodules (HAN) or tumors, by means of the cell dissociation technique. Mammary tissues were dissociated by means of collagenase (0.1%), hyaluronidase (0.1%), and pronase (1.25%). Aliquots of 10(5) viable cells in 0.01 ml medium were injected into the gland-free mammary fat pads of 3-week-old female syngeneic mice. After 10 weeks the outgrowths were examined and classified as ductal, HAN, tumor, or combinations of these types. The presence of HAN outgrowths indicated the presence of nodule-transformed cells in the donor mammary tissues. Nodule-transformed cells were recovered from 2-month-old donors, and the number of HAN outgrowths increased with donor age. Overt HAN and tumors did not appear in virgin female BALB/cfC3H/Crgl mice younger than 8 to 9 months of age. The data suggest that inapparent nodule-transformed cells occurred long before the appearance of HAN of tumors and that the numbers of transformed cells increased with donor age.
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PMID:Detection of inapparent nodule-transformed cells in the mammary gland tissues of virgin female BALB/cfC3H mice. 20 23

The concanavalin A (Con A)-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary epithelial cells was examined. Cells freshly dissociated from normal mammary glands, hyperplastic alveolar nodules, or primary mammary adenocarcinomas by collagenase digestion in the presence of bovine serum albumin were strongly agglutinated by low concentrations of Con A. After short-term culture in vitro, however, cells from all three types of tissue were only weakly agglutinated by Con A, as measured by both suspension and hemadsorption assays. By comparison, cells of three established mammary tumor culture lines agglutinated strongly in the presence of the lectin. Treatment of the normal, preneoplastic, and neoplastic mammary cells in primary cultures with either trypsin or collagenase had little or no effect on their agglutinability, whereas hyaluronidase significantly increased their reactivity. Studies with fluorescein-tagged Con A indicated that all three cell types were capable of binding the lectin. The results were consistent with previous evidence suggesting that neoplastic transformation of mouse mammary epithelial cells is not manifested in vitro by several of the alterations in growth patterns, intercellular interactions, and surface properties that usually accompany transformation of fibroblastic cells.
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PMID:Concanavalin A-induced agglutinability of normal, preneoplastic, and neoplastic mouse mammary cells. 28 51

A method of separating lymphoid cells from solid mouse mammary tumors was developed and evaluated. In this method the tumors are digested with 0.01% collagenase, 0.01% DNAase, and 0.025% trypsin in Dulbecco's PBS into suspensions of cells with a viability of 90%. The suspensions are fractionated on a continuous gradient of Ficoll in tissue culture medium. In model experiments this gradient was found to separate, cleanly, admixed cells of an established mammary tumor cell line and dissociated thymus glands. Recovery rates were 50% for the tumor cells and 80% for the thymocytes. The preparation of the cell suspensions and the gradient separation procedure are not harmful to the cells as indicated by trypan blue exclusion and the ability to grow in cell culture.
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PMID:In situ lymphoid cells of mouse mammary tumors. I. Development and evaluation of a method for the separation of lymphoid cells from mouse mammary tumors. 65 81

Transcription of the human collagenase I gene is induced by phorbol esters and repressed by glucocorticoids. Both types of regulation are mediated by the major enhancer element of the gene, which is localized between positions -73 and -65. The enhancer suffices to transmit positive and negative signals to a heterologous promoter or to a minimal promoter carrying only the TATA-box, both detected by the appearance of chloramphenicol-acetyl-transferase transcribed from the reporter gene linked to the promoters. Sequences 5' of the enhancer modulate its activity. Up- and down-regulation of gene constructs which contain only the collagenase enhancer linked to a heterologous promoter, are independent of ongoing protein synthesis, suggesting posttranslational modification of the transcription factor binding to the enhancer. Repression by glucocorticoids depends on an activated glucocorticoid receptor; a tenfold lower glucocorticoid concentration is needed for repression of the collagenase gene as compared to the activation of the mouse mammary tumor virus long terminal repeat. Immunoprecipitates of the dexamethasone receptor contain AP-1, suggesting a direct interaction of both transcription factors; this interaction may lead to the inactivation of AP-1. The action mechanism of phorbol esters and dexamethasone confirms the central role of AP-1 in proliferation control and tumor promotion. It appears that the most effective tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and the most effective anti-tumor promoter dexamethasone exert their action through the modulation of the same transcription factor.
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PMID:Positive and negative regulation of collagenase gene expression. 148 17

Gene regulation by steroid hormones is accomplished by a variety of different mechanisms leading to induction or repression of particular genes. These mechanisms are all mediated by a single class of intracellular hormone receptors, which in the unliganded state are maintained in an inactive form by association with other cellular proteins, including hsp90. Induction of the mouse mammary tumor virus (MMTV) requires binding of the hormone receptor to a hormone-responsive element (HRE) that is precisely organized in a phased nucleosome. After receptor binding, changes in chromatin structure are detected that correlate with binding of transcription factors, including nuclear factor I, to the MMTV promoter. However, although nuclear factor I acts as a basal transcription factor on the MMTV promoter it does not cooperate with the hormone receptors in terms of binding to free DNA, and mutation of the nuclear factor I binding site does not eliminate hormonal stimulation. This residual induction is mediated by octamer motifs upstream of the TATA box that bind the ubiquitous transcription factor OTF-1. Mutation of these octamer motifs does not influence basal transcription in vitro, but completely abolishes the stimulatory effect of progesterone receptor. Glucocorticoids also inhibit expression of many genes. The effect on the gene for the alpha-subunit of chorionic gonadotropin is due to DNA binding competition between the receptor and the protein mediating cAMP induction, whereas repression of the collagenase gene involves an interaction of the receptor with components of the AP1 complex, Jun and Fos.
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PMID:Transcriptional control by nuclear receptors. 201 57

The recent cloning of human androgen receptor (AR) cDNAs in this and other laboratories has provided valuable probes for investigating the structure and function of the AR at the molecular level. We now report the overexpression of a region of the human AR containing both the DNA- and hormone-binding domains in E. coli, which provides a means to produce large amounts of AR for analysis and use in functional studies. Under isopropyl-beta-D-thiogalactopyranoside induction, a tripartite protein, consisting of beta-galactosidase, a collagenase recognition site, and AR polypeptide, was produced in E. coli JM109 using pSS20 a as a vector. About 1 mg of the fused AR could be recovered per liter bacterial culture. The induced protein could readily be detected in a sodium dodecyl sulfate-polyacrylamide gel by Coomassie blue staining. Its identity was confirmed by Western blot analysis using antibodies to both beta-galactosidase and the AR. Scatchard analysis of the androgen-binding activity of the hybrid AR revealed high affinity binding to the synthetic androgen, Mibolerone (Kd, approximately 1.2 nM). Competition studies demonstrated the fusion protein's specificity for androgens. The hybrid receptor formed immune complexes with human anti-AR serum that sedimented at about 19S in 10-50% linear sucrose gradients containing 0.4 M KCl. Gel band shift assays revealed that the hybrid receptor protein forms specific complexes with a synthetic steroid response element derived from the mouse mammary tumor virus long terminal repeat region. These results demonstrate that the recombinant AR expressed in E. coli possesses many of the functional properties characteristic of DNA- and steroid-binding domains of the native AR.
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PMID:Overexpression of a partial human androgen receptor in E. coli: characterization of steroid binding, DNA binding, and immunological properties. 212 55

The transplantable pregnancy-dependent mouse mammary tumor line TPDMT-4 behaves like a preneoplastic lesion in virgin mice when implanted with tissue pieces. This study was conducted to elucidate whether enzymatic cell dissociation enhances the tumorigenic potential as in hyperplastic mammary nodules. When tissue pieces were implanted in virgin mice, there was an increase in tumor incidence from 0% at generation 14 (F14) to 40% at 38 (F38) during the 6-month observation; early (F8), middle (F16-18) and late (F39-40) transplant generation (ETG, MTG and LTG respectively) tumors were dissociated with collagenase and hyaluronidase. DDD strain females receiving an injection of 10(5) dissociated cells into the fat pad were observed as virgin or ovariectomized. ETG cells formed palpable tumors in 18 (43%) and 21 (50%) of 28 virgins at latent periods of 133 +/- 11 (mean +/- SE) and 142 +/- 10 days for 6 and 8 months respectively. MTG and LTG cells did so in 24 (60%) of 40 and 25 (89%) of 28 virgins at 77 +/- 5 and 68 +/- 5 days respectively for 6 months. In ovariectomized mice, however, no palpable tumors developed from any of these cells. Most ETG and MTG cell-derived tumors repeated palpable growth and total regression one or more times, and subsequently disappeared or grew slowly, whereas almost all LTG tumors grew progressively from the onset. MTG cells infiltrated into the fat pad more extensively than ETG and LTG cells: MTG cells occupied almost the whole fat pad at 6 weeks, whereas the outgrowths of the other cells were confined to one-eight of the fat pad. Southern blot analyses demonstrated the absence of certain extra MMTV DNA fragments in MTG tumors, although the distinct behaviors of MTG cells could not be ascribed to it alone. The results suggest that enzymatic cell dissociation may enhance tumorigenesis by hormone-dependent mammary tumor cells at lower hormone levels.
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PMID:Enhancement of tumorigenic potential in virgin mice of a pregnancy-dependent mouse mammary tumor (TPDMT-4) by enzymatic cell dissociation. 283 7

Selenium is an essential dietary trace element which has anticancer properties. Among its effects in rats, selenium has been shown to inhibit the development of carcinogen-induced mammary tumors by interfering with the postinitiation, promotion phase of carcinogenesis. We studied the effects of selenium on the growth of rat mammary tumor cells in primary culture. Our objective was to determine whether selenium had any direct influence on cell growth which might explain its influence on tumor development. Rat mammary tumors were induced by N-nitrosomethylurea. Tumor epithelium was prepared by collagenase dispersion and the cells were separated by Ficoll gradient centrifugation. The tumor epithelium was grown in primary culture using a defined serum-free medium. The addition of low concentrations of sodium selenite, less than 1.0 micrograms/ml, stimulated tumor cell proliferation. Protein synthesis and the production of type IV collagen increased within the first hour of exposure, prior to any measurable increase in DNA synthesis. Concentrations of selenite greater than 1.0 micrograms/ml inhibited cell proliferation, the synthesis of protein, and the replication of DNA in a dose-related manner. These studies demonstrated that selenium has the potential to influence the postinitiation phase of rat mammary tumorigenesis by directly altering the growth of tumor cells, possibly through the regulation of protein synthesis.
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PMID:Influence of selenium on the growth of N-nitrosomethylurea-induced mammary tumor cells in culture. 403 31


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