Heparin Inhibits the Progression Phase of Subcultured Endothelial Cell Proliferation in Rat Aorta

Abstract

ABSTRACT-The anti-proliferative effects of heparin on subcultured endothelial cells (EC) of rat aorta were investigated to determine whether heparin inhibits the competence phase or the progression phase in the cell cycle using the starting time and the rate of proliferation. Fetal bovine serum (FBS) stimulated EC proliferation increased to 1.5-times in cell number, but decreased to 0.5-times in 3H-thy midine incorporation, compared with the proliferation of rat primary cultured smooth muscle cells (SMC). The FBS-effects on EC proliferation were attributed to the progression phase rather than the competence phase. Heparin (1, 10 or 100pg/ml) significantly inhibited the proliferation of FBS (5%) stimulated EC, and the extent of inhibition was the same in both cell number and 3H-thymidine incor poration. In the 3H-thymidine incorporation every 3 hr, heparin reduced the rate of incorporation into Go-arrested EC, but did not affect the starting time of DNA synthesis. When the index of competence phase, starting time, was plotted against that of progression phase, rate of proliferation, the inhibition of heparin was attributed to the progression phase. These results demonstrate that heparin selectively inhibits the progression phase in subcultured EC of rat aorta.

Heparin down‐regulates the phorbol ester‐induced protein kinase C gene expression in human endothelial cells: enzyme‐mediated autoregulation of protein kinase C‐α and ‐δ genes1

“…Heparin and heparan sulfate are complex glycosaminoglycans that exert antiproliferative effects in different cell types [32,33,14–16]. Consonant with growth inhibition, heparin inhibits the expression of the early proto‐oncogenes c‐fos and c‐myc by acting selectively on a PKC‐dependent pathway [18–20].…”

“…The crucial role of PKC in transducing growth regulatory signals is also highlighted by the finding that the down‐regulation of PKC‐dependent pathways elicits growth inhibitory responses. In particular, glycosaminoglycan‐mediated inhibition of cell proliferation [14–16] and angiogenesis [17] has been associated, at least in part, to the ability of heparin and heparan sulfate to counteract PKC‐mediated events [18–20]. In this regard, we have recently shown that heparin markedly reduced both the serum‐ and phorbol ester‐stimulated DNA synthesis in HEC by eliciting the down‐regulation of the PKC‐mediated ornithine decarboxylase gene expression (ODC) [21].…”

Chemical Structure-Activity of Cnidium Rhizome-Derived Phthalides for the Competence Inhibition of Proliferation in Primary Cultures of Mouse Aorta Smooth Muscle Cells

“…We have previously analyzed PDGF and FBS-stimulated competence of DNA synthesis by a convenient method (7,12). Heparin does not inhibit the PDGF-induced compe tence phase, suggesting that it inhibits the progression phase in the SMC (7).…”

“…Analysis of indices of competence and progression inhibi tions We analyzed the inhibitory effects of cnidium rhizome derived phthalides on competence and progression phases of SMC proliferation by using the convenient assay reported previously (7,12). Proliferation lines of the SMC number from 3 x 104 to 6 x 104 cells/well as a func tion of culturing time were fitted to the individual data of SMC number by the least-squares method.…”

“…Proliferation lines of the SMC number from 3 x 104 to 6 x 104 cells/well as a func tion of culturing time were fitted to the individual data of SMC number by the least-squares method. These indices of the competence and progression inhibitions were esti mated as relative difference of the starting time between with and without drug, ((Ct Cc)/Cc), and relative differ ence of the doubling time from the starting time, which was calculated by the slope of the proliferation line, be tween with and without drug, ((Pt Pc)/Pc), respectively (7,12).…”