Mechanism of betulinic acid inhibition of collagen biosynthesis in human endometrial adenocarcinoma cells
Abstract:
Collagen as a ligand for integrin receptors plays important role in the integrin – dependent regulation of cellular metabolism. Since betulinic acid (BA) evokes anticancer activity, its effect on collagen biosynthesis was studied in cultured endometrial adenocarcinoma cells. Confluent cells were treated with different concentrations of BA for 24 hours. It was found that BA inhibit collagen biosynthesis ([3H] proline incorporation assay). The mechanism of this phenomenon was found at the level of insulin-like growth factor-I receptor (IGF-IR) and α2 integrin signalling (Western immunoblot analysis). The expressions of IGF-I receptor and α2 integrin subunit as well as integrin activated focal adhesion kinase (FAK) were decreased in the cells treated with BA. It was accompanied by a parallel decrease in the expression of Sos protein and phosphorylated MAP-kinases (ERK1, ERK2) and up – regulation of NF-κB. The data suggest that BA-dependent inhibition of collagen biosynthesis in cultured human endometrial adenocarcinoma cells undergoes through α2 integrin and IGF-IR signaling that activate NF-κB, potent inhibitor of collagen gene expression.