Plasminogen activation transforms the morphology of quiescent 3T3 cell monolayers and initiates growth

Whur, P; Silcox, J. J.; Boston, Julie; Williams, Donald C.

doi:10.1038/bjc.1979.126

Cited by 8 publications

(2 citation statements)

References 40 publications

(39 reference statements)

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“…Cells with > 95% viability were suspended from pooled tumours, using the techniques of Stephens et al (1977) (Whur et al, 1979).…”

Section: Methodsmentioning

confidence: 99%

Plasminogen activator in cultured Lewis lung carcinoma cells measured by chromogenic substrate assay

Whur¹,

Magudia²,

Boston³

et al. 1980

Br J Cancer

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Summary.-A chromogenic substrate assay for the plasminogen activator (PA) activity of Lewis lung carcinoma cells has been developed. The cells were incubated with plasminogen, the activation of which to plasmin was measured by the amidolysis of the chromogenic substrate S-2251. This was routinely performed as a 4h serum-free assay, but a variation lasting 24h, in medium supplemented with plasminogen-free inhibitor-reduced serum, produced similar results. The assay also detected PA released into the medium. PA activity was proportional to cell density, and the assay was non-toxic to the cells.Assays were performed on cultures derived from primary and metastatic tumours. Host cells were effectively eliminated from such cultures but, because of an initial phase of tumour-cell death, PA assays were not carried out until cultures became established. No consistent difference was detected between PA levels in primary and metastatic cultures. However, these cultures were shown to be atypical of the parent tumour; they grew slowly when reinjected at the primary site, and their metastatic potential was impaired.

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“…Cells with > 95% viability were suspended from pooled tumours, using the techniques of Stephens et al (1977) (Whur et al, 1979).…”

Section: Methodsmentioning

confidence: 99%

Plasminogen activator in cultured Lewis lung carcinoma cells measured by chromogenic substrate assay

Whur¹,

Magudia²,

Boston³

et al. 1980

Br J Cancer

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“…The examples of cell-surface proteinases and their inhibitors are already known (2)(3)(4)(5), and the importance of proteolytic regulations in cell adhesion and differentiation was already emphasized in independent studies (6)(7)(8). In the search for a potential proteinase precursor, we have concentrated our attention on one of the most important adhesive molecules, fibronectin (FN).…”

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confidence: 99%

Potential proteolytic activity of human plasma fibronectin.

Keil-Dlouhá¹,

Planchenault²

1986

Proc. Natl. Acad. Sci. U.S.A.

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Evidence is presented that fibronectin (FN) polypeptide chain contains a latent proteinase. Human plasma FN was cleaved with cathepsin D into three main fragments: 140-kDa and 70-kDa single-chain and 140-kDa double-chain polypeptides. Their separation was achieved according to their affinity for heparin-Sepharose. A single-chain 140-kDa fragment (H-1) was eluted in the first peak. This peptide corresponds to the already described fragment that originates from the central part of FN; it contains a low-affinity heparinbinding site, one free SH group, and a cell-binding site. After reduction and further purification by preparative polyacrylamide gel electrophoresis, this fragment revealed a spontaneous decomposition, which could be attributed to proteolytic degradation. The subfragments, ranging from 25 to 95 kDa, yielded the same proteolytically active doublet of 28-30 kDa when tested by NaDodSO4/polyacrylamide gel electrophoresis in a gel containing copolymerized gelatin or fibrinogen. The proteolytic activity was inhibited by specific SH proteinase inhibitors. The proteinase forms a labeled complex after its incubation with '25I-labeled cystatin. Neither FN, cathepsin D, nor any products from previous purification steps were proteolytically active under the conditions of the assay. It was suggested that the same fragment may also yield an inhibitor, since structural analogies were found between the cell-binding region of FN and SH proteinase inhibitors.During our previous studies of cell-surface proteins in the differentiation process, we observed that some of their changes could be attributed to proteolysis (1). The examples of cell-surface proteinases and their inhibitors are already known (2-5), and the importance of proteolytic regulations in cell adhesion and differentiation was already emphasized in independent studies (6-8). In the search for a potential proteinase precursor, we have concentrated our attention on one of the most important adhesive molecules, fibronectin (FN).FN exhibits a large variety of biological functions. It plays a role in embryonic differentiation, cell-cell aggregation, cell-substratum adhesion, cell spreading, opsonization of bacteria, wound healing, maintenance of the nontransformed phenotype, etc. (for reviews, see refs. 9-11).FN is a large glycoprotein containing two polypeptide chains, each 220 kDa for the cellular and secreted forms, and 220 and 210 kDa for the plasma form. Partial primary structure data have revealed highly conserved amino acid sequences in insoluble cellular and soluble plasma forms of FN as well as among FNs from different species (12)(13)(14)(15). This molecule contains several domains with binding affinity for different substrates including collagen, heparin, fibrin, DNA, actin, cell surfaces, bacteria, and itself (9-11).Among different proteolytic enzymes used for the specific cleavage of FN into functional domains, cathepsin D has been frequently used (16,17 (15,18,19), it contains a low-affinity heparin-binding site, one free SH group, and th...

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Use of Cell Culture to Identify Human Precancer

Lyko

Hartmann

1984

Advances in Experimental Medicine and Biology

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Plasminogen activation transforms the morphology of quiescent 3T3 cell monolayers and initiates growth

Cited by 8 publications

References 40 publications

Plasminogen activator in cultured Lewis lung carcinoma cells measured by chromogenic substrate assay

Plasminogen activator in cultured Lewis lung carcinoma cells measured by chromogenic substrate assay

Potential proteolytic activity of human plasma fibronectin.

Use of Cell Culture to Identify Human Precancer

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