Amphiregulin and hepatocyte-derived extracellular matrix regulate proliferation and autocrine growth factor expression in colon cancer cell lines of varying liver-colonizing capability

We studied the effect of two members of the epidermal growth factor (EGF) f amily-amphiregulin and heparin-binding EGF-like growth factor (HB-EGF)-on c ell proliferation, growth factor and growth factor receptor expression, and cell differentiation in two human colon cell lines of varying liver-coloni zing potential. The effect of amphiregulin and HB-EGF was assessed both in cells grown on plastic, as well as on cells grown on hepatocyte-derived ext racellular matrix (ECM). We found that both colon cell lines were sensitive to HB-EGF stimulation of cell proliferation. Amphiregulin inhibited cell p roliferation in KM12 cells and stimulated the strongly metastatic cell line KM12SM to a slight extent. When the cells were cultured on hepatocyte-deri ved ECM, amphiregulin inhibited the weakly metastatic KM12 and stimulated t he growth of KM12SM. HB-EGF synergistically acted with hepatocyte-derived E CM to enhance cell proliferation in both colon cell lines. Expression of li gands of the EGF family, such as transforming growth Factor-alpha (TGF-alph a) and amphireguiin, was decreased in both cell lines when cultured on ECM. Hepatocyte-derived ECM decreased expression of cripto in KM12 and increase d it in KM12SM cells. Neither cripto nor TGF-alpha mRNA levels was affected by growing the cells in the presence of amphiregulin. However, amphireguli n increased expression of its own mRNA in; the weakly metastatic KM12 and d ecreased it in the strongly metastatic KM12SM when the cells were cultured on plastic. Amphiregulin and HB-EGF stimulated expression of erb-B2 in both cell lines cultured on plastic. Surprisingly, when the cells were grown on hepatocyte-derived ECM, amphiregulin inhibited erb-B2 expression in both c ell lines. We observed no effect of amphiregulin on cell differentiation as assessed by alkalin-ephosphatase expression. Our studies demonstrate one m echanism that could play a role in site-specific metastasis. We found an in hibitory response to an autocrine growth factor in the context of hepatocyt e-derived ECM in a weakly metastatic cell and a stimulatory effect of the s ame growth factor when strongly metastatic cells were cultured on the same ECM. (C) 1999 Wiley-Liss, Inc.