Modulation of growth of human carcinoma SW‐13 cells by heparin and growth factors

Abstract

This study reports on the effects of heparin, basic and acidic fibroblast growth factors (bFGF and aFGF, respectively), and transforming growth factor type-e (TGFe) on the growth of a human adrenocortical carcinoma cell line, SW-13. Heparin has previously been shown to inhibit growth in several cell types, including smooth muscle cells, certain fibroblasts, and epithelial cells, and to modulate the effects of fibroblast growth factors. Whereas bFGF and aFGF bind tightly to heparin and elute from a heparin-Sepharose column with 2 M NaCl and 1.6 M NaCl, respectively, TGFe binds to heparin with lower affinity and can be eluted from heparin-Sepharose column with 0.5 M NaCl. TGFe is a polypeptide unrelated to FGF, is present in neoplastic and nonneoplastic tissues, and stimulates the growth of certain epithelial cells and fibroblasts in soft agar and monolayer. Since the growth of SW-13 cells is stimulated by TGFe and by bFGF, we hypothesized that heparin would inhibit the growth of SW-13 cells by binding to these growth factors and that the effects of heparin could be overcome with the addition of either growth factor. Our experiments confirmed that heparin inhibits the growth of SW-13 cells. A dose-dependent growth inhibition was observed in both monolayer and soft agar. The inhibition in monolayer was partially reversed upon heparin withdrawal. The effects of heparin in both monolayer and soft agar were at least partially overcome by TGFe and by basic or acidic FGF. Overall protein synthesis does not appear to be affected by heparin as measured by [35S]methionine uptake. In contrast, epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) were unable to overcome heparin-induced inhibition both in monolayer and in soft agar. Heparin also inhibited [3H]thymidine incorporation in AKR-2B and partially inhibited AKR-2B cell stimulation by TGFe; however, it further potentiated the already potent stimulation by bFGF. We propose that heparin, TGFe, bFGF, and aFGF modulate the growth of SW-13 cells and possibly of other epithelial cells in complex ways and that heparin-like substances present in the extracellular matrix play an important role in the control of epithelial growth.

Growth factor‐independent proliferation of normal human neonatal keratinocytes: Production of autocrine‐ and paracrine‐acting mitogenic factors

“…Since we have shown that heparin does not inhibit the mitogenic effect of EGF, TGFa, or aFGF on keratinocytes or AKR-2B cells (data not shown), novel heparin-sensitive growth factors may have been produced by autonomously growing keratinocytes. In this regard, several other groups have reported potentially novel growth factors which display similar properties (Halper and Carter, 1989;Masuda et al, 1987). Heparin and heparan have been shown to exert antiproliferative effects on several cell types in vitro and in vivo (Hook et al, 1984;Shipley et al, 1989;Clowes and Karnovsky, 1977;Imamura and Mitsui, 1987;Majesky et al, 1987;Robertson and Goldstein, 1988;Wright et al, 1989).…”

Antiproliferative effects of heparin on normal and transformed NIH/3T3 fibroblasts.

“…Thus, these physiological components of the extracellular matrix have been defined "growth modulators" for two reasons: they bind growth factors -and possibly growth inhibitors -thus regulating their availability for receptor interaction at the cell surface; their effects could be either stimulatory or inhibitory on proliferation according to the cell type and/or to growth factor requirements (Gordon et al, 1987;Roberts et al, 1988). In fact, heparin stimulates endothelial cell growth (Sommer and Rifkin, 1989;Damon et al, 1989), whereas it inhibits the proliferation of vascular smooth muscle cells (Williams and Mason, 1991), renal mesangial cells (Adler and Eng, 1990), rat cervical epithelial cells (Striker et al, 1991), fibrib1asts (Striker et al, 1991), and transformed cell lines (Halper and Carter, 1989). Stimulation of endothelial cell growth by heparin is due to interaction with FGF (Fibroblast Growth Factor), leading to ligand/receptor stabilization (Sommer and Rifkin, 1989); however, the mechanism(s) underlying the growth inhibitory effects are 1065-6995/93/080781-06/$08.00 /0 still not completely defined.…”

Structural determinants of antiproliferative activity of heparin on pulmonary artery smooth muscle cells

“…Besides its anticoagulant activity, HP has a variety of other biological and biochemical activities that include the following: 1) regulation of lipid metabolism (17), 2) control of blood fluidity at the endothelial surface (50), 3) control of cell attachment to various proteins in the extracellular matrix (ECM) (42,43,73), 4) binding with acidic and basic fibroblast growth factors (3,61), 5) binding to interleukin-3 and granulocyte-macrophage colony-stimulating factor (27,59), and 6) inhibition of serotonin-induced pulmonary artery (PA) smooth mus-cle cell (SMC) hypertrophy (44). HP stimulates endothelial cell growth (69), whereas it inhibits the proliferation of renal mesangial cells (65), rat cervical epithelial cells (1), transformed cell lines (5,16,30), and systemic SMCs and PASMCs (18,68). Of the types of biological activities just mentioned, anticoagulation has been extensively discussed in several reviews (6,15,36,48,76).…”