Sc. Presnell et al., ESTABLISHMENT OF A FUNCTIONAL HGF C-MET AUTOCRINE LOOP IN SPONTANEOUSTRANSFORMANTS OF WB-F344 RAT-LIVER STEM-LIKE CELLS/, Hepatology, 28(5), 1998, pp. 1253-1259
A model of spontaneous malignant transformation was used to evaluate t
he molecular changes that take place in WB-F344 rat liver epithelial c
ells during neoplastic transformation and tumorigenesis, A comparison
of wild-type low-passage WB-F344 cells to spontaneously transformed tu
mor cell lines revealed that the majority of the tumor cell lines have
an increased capacity for autonomous proliferation and motility when
maintained in serum-free media. In the current study, we show that c-m
ct is expressed at some level in wild-type WB-F344 cells and in all of
the spontaneously transformed tumor cell lines, and that 9/16 of the
tumor cell lines have acquired hepatocyte growth factor (HGE) expressi
on. In vitro growth of HGF-expressing tumor cell lines is inhibited as
much as 68% by the addition of neutralizing antibodies to HGF or anti
sense HGF oligonucleotides, indicating that the production of HGF by t
he tumor cells is partially responsible for driving autonomous prolife
ration in a subset of tumor cell lines. Furthermore, conditioned media
collected from HGF-expressing tumor cell lines stimulates DNA synthes
is in wild-type WB-F344 cells, and this effect can be abrogated by pre
-incubation of the conditioned media with neutralizing antibodies to H
GE Because HGF is a motility-promoting growth factor, all cell lines w
ere evaluated to determine if expression of HGF stimulated motogenesis
, All turner cell lines (regardless of HGF expression) were highly mot
ile in comparison with wild-type WB-F344 cells, with a 3.5-fold to 20-
fold greater number of motile cells. The high basal rate of motility c
haracteristic of the tumor cell lines is not a result of the productio
n of HGF, because it is also a property of the cell Lines that do not
express HGF messenger RNA. Furthermore, tumor cell motility is not inh
ibited by antisense oligonucleotides or neutralizing antibodies. Estab
lishment of an autocrine HGF/c-met loop in a subset of spontaneously t
ransformed WB-F344 cell lines may influence development and/or express
ion of the tumorigenic phenotype by driving cellular proliferation.