The effects of bestatin, a microbial aminopeptidase inhibitor, on epidermal growth factor-induced DNA synthesis and cell division in primary cultured hepatocytes of rats

The present investigation examines the responsiveness of the gastric mucosa to the growth-promoting action of epidermal growth factor (EGF) during advancing age. Two sets of experiments were performed. In the first set of experiments, groups of 4-, 8-, 16-, and 24-mo-old Fischer 344 rats were injected subcutaneously at 12-h intervals for 2 days with either EGF (10 micrograms/kg) in gelatin or the vehicle only (controls). The animals were killed 16-18 h after the last injection. The oxyntic gland mucosa was assayed for thymidine kinase and the rate of DNA synthesis in vitro (indicators of proliferative activity) as well as for tyrosine kinase (Tyr-k) activity. In control rats, the rate of DNA synthesis and thymidine kinase activity rose steadily between 4 and 24 mo of age. However, whereas Tyr-k activity in the gastric mucosal cytosol changed only marginally with age, activity of the enzyme in the membrane fraction rose steadily between 4 and 16 mo and then increased abruptly. EGF stimulated gastric mucosal DNA synthesis and thymidine kinase activity in 4- to 16-mo-old rats compared with the corresponding controls, but in the 24-mo-old animals, it caused a significant 40-50% inhibition. EGF had no demonstrable effect on Tyr-k activity in either cytosolic or membrane fraction. We postulated that Tyr-k activity might have returned to basal level 16-18 h after the last EGF injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Aluminofluoride- and Epidermal Growth Factor-Stimulated DNA Synthesis in MOB 3-4-F2 Cells

Pharmacology & Toxicology ◽

10.1111/j.1600-0773.1991.tb01306.x ◽

1991 ◽

Vol 69 (5) ◽

pp. 330-337 ◽

Cited By ~ 8

Author(s):

Tomoyuki Kawase ◽

Michiaki Orikasa ◽

Akitoshi Suzuki

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Dna Synthesis ◽

Epidermal Growth

Download Full-text

The calcium signal for BALB/MK keratinocyte terminal differentiation counteracts epidermal growth factor (EGF) very early in the EGF-induced proliferative pathway

Molecular and Cellular Biology ◽

10.1128/mcb.8.2.557-563.1988 ◽

1988 ◽

Vol 8 (2) ◽

pp. 557-563

Author(s):

P P Di Fiore ◽

J Falco ◽

I Borrello ◽

B Weissman ◽

S A Aaronson

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Dna Synthesis ◽

Fold Increase ◽

Inhibitory Effect ◽

Lymphoid Cells ◽

Epidermal Keratinocytes ◽

Calcium Signal ◽

High Calcium ◽

Epidermal Growth

BALB/MK mouse epidermal keratinocytes require epidermal growth factor (EGF) for proliferation and terminally differentiate in response to high calcium concentrations. We show that EGF is an extremely potent mitogen, causing BALB/MK cultures to enter the cell cycle in a synchronous manner associated with a greater than 100-fold increase in DNA synthesis. Analysis of the expression of proto-oncogenes which have been reported to be activated during the cascade of events following growth factor stimulation of fibroblasts or lymphoid cells revealed a very rapid but transient 100-fold increase in c-fos RNA but little or no effect on the other proto-oncogenes analyzed. Exposure of EGF-synchronized BALB/MK cells to high levels of calcium was associated with a striking decrease in the early burst of c-fos RNA as well as the subsequent peak of cell DNA synthesis. Since the inhibitory effect of high calcium on c-fos RNA expression was measurable within 30 min, our studies imply that the EGF proliferative and calcium differentiation signals must interact very early in the pathway of EGF-induced proliferation. Our results also establish that c-fos RNA modulation is an important early marker of cell proliferation in epithelial as well as mesenchymal cells.

Download Full-text

Epidermal growth factor-mediated effects on equine vascular smooth muscle cells

AJP Cell Physiology ◽

10.1152/ajpcell.1988.255.4.c447 ◽

1988 ◽

Vol 255 (4) ◽

pp. C447-C451 ◽

Cited By ~ 15

Author(s):

D. A. Grosenbaugh ◽

M. S. Amoss ◽

D. M. Hood ◽

S. J. Morgan ◽

J. D. Williams

Keyword(s):

Smooth Muscle ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Dna Synthesis ◽

Vascular Smooth Muscle Cells ◽

Cellular Proliferation ◽

Epidermal Growth ◽

Dose Dependent

Epidermal growth factor (EGF) receptor binding kinetics and EGF-mediated stimulation of DNA synthesis and cellular proliferation were studied in cultured vascular smooth muscle cells (VSMC) from the equine thoracic aorta. Binding studies, using murine 125I-labeled EGF, indicate the presence of a single class of high-affinity binding sites (apparent KD = 2.8 X 10(-11) M), with an estimated maximal binding capacity of 5,800 sites/cell. EGF stimulated [3H]thymidine uptake in confluent quiescent monolayers in a dose-dependent fashion, half-maximal stimulation occurring at 7.5 X 10(-11) M. Likewise, EGF-mediated cellular proliferation was dose dependent (50% effective dose = 5 X 10(-11) M) under reduced serum concentrations. Equine VSMC contain specific receptors for EGF, and EGF can stimulate DNA synthesis and proliferation in these cultured cells, which suggests that EGF may participate in the proliferative changes observed in equine distal digital peripheral vascular disease.

Download Full-text

An overexpressed gene transcript in senescent and quiescent human fibroblasts encoding a novel protein in the epidermal growth factor-like repeat family stimulates DNA synthesis.

Molecular and Cellular Biology ◽

10.1128/mcb.15.1.120 ◽

1995 ◽

Vol 15 (1) ◽

pp. 120-128 ◽

Cited By ~ 73

Author(s):

B Lecka-Czernik ◽

C K Lumpkin ◽

S Goldstein

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Dna Synthesis ◽

Cellular Proliferation ◽

Werner Syndrome ◽

Human Fibroblasts ◽

Extracellular Proteins ◽

Gene Transcript ◽

Epidermal Growth ◽

Novel Protein

We carried out subtractive enrichment of a cDNA library derived from mRNA of senescent human diploid fibroblasts (HDF) established from a subject with Werner syndrome of premature aging. By differential screening, we isolated an overexpressed cDNA sequence (S1-5) that codes for a novel protein containing epidermal growth factor (EGF)-like domains which match the EGF-like consensus sequences within several known extracellular proteins that play a role in cell growth, development, and cell signalling. S1-5 mRNA is overexpressed in Werner syndrome and senescent normal HDF, is induced by growth arrest of young normal cells, but is significantly decreased by high serum, conditions which promote cellular proliferation. Paradoxically, microinjection into young HDF of two different lengths of S1-5 mRNA, containing different putative AUG translational start sites, consistently stimulated rather than inhibited DNA synthesis by an apparent autocrine/paracrine mechanism. Thus, the S1-5 gene product may represent a negative and/or positive factor whose ultimate activity is modulated by the cell environment as occurs with other members of EGF-like family.

Download Full-text

Effects of epidermal growth factor on diamine oxidase expression and cell growth in Caco-2 cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.261.4.g669 ◽

1991 ◽

Vol 261 (4) ◽

pp. G669-G676 ◽

Cited By ~ 3

Author(s):

B. Daniele ◽

A. Quaroni

Keyword(s):

Cell Proliferation ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Dna Synthesis ◽

Intestinal Mucosa ◽

Diamine Oxidase ◽

Small Intestinal Mucosa ◽

Cell Proliferation And Differentiation ◽

Proliferation And Differentiation ◽

Epidermal Growth

To investigate the role of diamine oxidase (DAO) in the intestinal mucosa, we compared its expression with cell proliferation and differentiation in the human colon carcinoma cell line Caco-2. DAO synthesis was evaluated in subconfluent and confluent cultures and in the presence of epidermal growth factor (EGF), a polypeptide hormone known to have specific trophic effects on the small intestinal mucosa. EGF stimulated DNA synthesis, significantly increased cellular DAO activity and the amount of enzyme secreted into the culture medium, but decreased expression of dipeptidyl peptidase IV, a marker of cell differentiation in confluent Caco-2 cells. Immunoprecipitation of DAO from cells labeled metabolically with [35S]methionine failed to demonstrate an increased enzyme synthesis in EGF-treated cells, suggesting that this hormone acted primarily at a posttranslational level by reducing DAO degradation before intracellular storage or secretion. A possible relationship between changes in cellular DAO activity and cell proliferation was also investigated by using aminoguanidine, a specific and potent DAO inhibitor. Although DAO activity was markedly suppressed, aminoguanidine had no significant effects on the rate of DNA synthesis. These results demonstrated that in Caco-2 cells EGF stimulated DNA synthesis and DAO expression; however, cell proliferation and differentiation were not correlated with the levels of cellular DAO, suggesting that this enzyme does not play a major role in the regulation of intestinal epithelial cell turnover.

Download Full-text