Inhibitors of chymotrypsin-like activities selectively block the mitotic pathway in rat hepatoma cells.
We provide evidence that both covalent and non-covalent inhibitors of chymotrypsin-like activities inhibit the insulin-induced DNA replication, while the hormonal metabolic effects such as induction of tyrosine aminotransferase activity or increase of amino-acid transport remain unchanged. Besides, the protease inhibitors that we tested were without any effect on both the autocatalytic phosphorylation of insulin receptors and the tyrosine kinase activity towards poly(glutamate/tyrosine). The inhibitory effect of protease inhibitors on DNA synthesis was also visible when fibroblast growth factor (FGF) was used to commit cells in the proliferative cycle. This observation proves that the involvement of a putative protease is not restricted to the insulin mitogenic pathway. Finally, we observed that Fao cells totally escaped the inhibitory action of a covalent inhibitor of chymotrypsin after having been exposed to insulin for 10 h. We propose that a chymotrypsin-like activity is involved in the intracellular signalling leading to the proliferation of rat hepatoma cells up to a non-return point situated in the middle of G1 (6-8 h).
Ponzio
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G
Unité INSERM U210, Faculté de Médecine, Nice, France.
Contreres
J O
JO
Debant
A
A
Auberger
P
P
Farahifar
D
D
Rossi
B
B
D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D004261:DNA Replication / Q000187:drug effects; D010450:Endopeptidases / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D005434:Flow Cytometry; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007399:Interphase; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis; D010766:Phosphorylation; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D014108:Tosylphenylalanyl Chloromethyl Ketone / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014444:Tyrosine Transaminase / Q000378:metabolism
D000621:Aminoisobutyric Acids; D007328:Insulin; C100049:2-aminoisobutyric acid; D014108:Tosylphenylalanyl Chloromethyl Ketone; D005346:Fibroblast Growth Factors; D014444:Tyrosine Transaminase; D011972:Receptor, Insulin; D010450:Endopeptidases; D002918:Chymotrypsin