HEPATOCYTE GROWTH-FACTOR STIMULATES INVASION ACROSS RECONSTITUTED BASEMENT-MEMBRANES BY A NEW HUMAN SMALL-INTESTINAL CELL-LINE

Hepatocyte growth factor/scatter factor (HGF/SF) is a protein growth f actor whose pleiotropic effects on epithelial cells include the stimul ation of motility, mitosis and tubulogenesis. These responses are medi ated by the cell surface tyrosine kinase receptor c-met. Because both the cytokine and receptor are found in the gastrointestinal tract, we have studied the effects of HGF/SF on transformed gut epithelial cells which express c-met. Here we describe the response of a new transform ed human jejunal epithelioid cell line (HIE-7) to HGF/SF. Morphologica lly HIE-7 cells are immature. Their epithelial lineage was confirmed b y reactivity with the epithelial specific antibodies AE1//AE3, Cam 5.2 , Ber-EP4 and anti-EMA and is consistent with their expression of c-me t mRNA and protein. In addition, electron microscopic analysis reveale d the presence of primitive junctions and rudimentary microvilli, but features of polarization were absent. When grown on reconstituted base ment membranes, HIE-7 cells formed closely associated multicellular co rd-like structures adjacent to acellular spaces. However, the cells di d not mature structurally, form lumen-like structures or express disac charidase mRNA, even in the presence of recombinant HGF (rHGF). On the other hand, rHGF induced HIE-7 cells to scatter and stimulated their rapid migration in a modified wound assay. To determine whether the mo togenic effect caused by rHGF is associated with HIE-7 cell invasivene ss across reconstituted basement membranes, a Boyden chamber chemoinva sion assay was performed. rHGF stimulated a 10-fold increase in the nu mber of HIE-7 cells that crossed the basement membrane barrier, while only stimulating a small increase in chemotaxis across a collagen IV m atrix, suggesting that the cytokine activates matrix penetration by th ese cells. rHGF also stimulated the invasion of basement membranes by an undifferentiated rat intestinal cell line (IEC-6) and by two human colon cancer cell lines which are poorly differentiated (DLD-1 and SW 948). In contrast, two moderately well differentiated colon cancer cel l lines (Caco-2 and HT-29) did not manifest an invasive response when exposed to rHGF. These results suggest that HGF/SF may play a signific ant role in the invasive behavior of anaplastic and poorly differentia ted gut epithelial tumors.