The potential of transforming growth factor-β (TGF-β) to modulate the growth of endothelial cells via alterations in the cell's extracellular matrix (ECM) was examined. Rat brain endothelial cells were cultured in the presence or absence of TGF-β, and subsequently ECM was prepared from the cell cultures by hypotonic lysis of the cells. Untreated endothelial cells were then cultured on the various matrices. Cells grown on TGF-β-treated ECM showed a significant decrease in cell number (41 ± 6% mean growth inhibition at 6 days, P < 0.005 by paired T-test) compared with cells grown on untreated ECM. The growth inhibitory activity of the ECM was depleted by 9 days of culture, and resumption of exponential cell growth was observed. A similar phenomenon was observed if anti-TGF-β neutralizing antibodies were incubated with the ECM. When the TGF-β-treated matrix was exposed to a brief dithiothreitol treatment in order to inactivate residual TGF-β, an approximately equal degree of growth inhibition was observed initially, but the reversal of inhibition occurred at an earlier time point than that with unreduced TGF-β-treated matrix. Analyses of the composition of matrices synthesized in the presence or absence of TGF-β revealed about a twofold increase in the accumulation of various radioactive metabolic precursors in the TGF-β-treated matrices. However, no qualitative alterations in the matrix or cellular-associated proteins or glycoproteins were observed, as analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. An increase in cell-associated heparan sulfate, however, was observed in TGF-β-treated cells. The results suggest that certain growth regulatory effects of TGF-β may be mediated, at least in part, by alterations in the ECM.
|Number of pages||6|
|Journal||Experimental Cell Research|
|State||Published - Sep 1990|
Bibliographical noteFunding Information:
The studies were supported by grants from the John S. Dunn Foundation, The Preuss Foundation, The University Cancer Foundation, and by NIH Grant ROl CA42729. The scanning electron microscopy was generously performed by Dr. G. Nicolson and supported by NC1 Core Grant P30-CA16672. The authors also thank Mary Sirrieh for her assistance in the preparation of this manuscript and Dr. Paula Belloni for her help in isolation and characterization of the endothelial cells.
ASJC Scopus subject areas
- Cell Biology