Transforming growth factors produced by normal and neoplastically transformed XXXX liver epithelial cells in culture.

@entity5428 @entity2482 @entity5 @entity1810 @entity35 @entity18696
The secretion of transforming growth factors (TGFs) alpha and beta by normal, chemically transformed, and malignant @entity35 liver epithelial cell lines was investigated. The WB-F344 normal cultured @entity35 liver epithelial cell line does not secrete an epidermal growth factor-like (putatively @entity18696 ) activity, but several clonal cell strains derived from WB-F344 cells which had been treated with @entity2482 , especially those that expressed high levels of @entity5428 transpeptidase, secreted @entity18696 -like activity into their conditioned media. Cell lines obtained from @entity5 which were produced by these cell strains varied in their abilities to secrete @entity18696 , even though they all expressed high levels of @entity5428 transpeptidase activity. When two of the non- @entity18696 -secreting @entity5 cell lines were transplanted into isogeneic @entity35 , the @entity5 that formed contained high levels of @entity18696 -like activity. Although epidermal growth-factor (hence, @entity18696 also) inhibited the proliferation of several of these @entity5 cell lines in monolayer cultures, this growth factor often paradoxically stimulated the anchorage-independent growth of the same cell lines. In contrast to @entity18696 -like activity, all cell lines/strains released @entity1810 activity into their conditioned media. However, while both normal or chemically transformed cell strains typically produced the inactive form of @entity1810 , the @entity5 cell lines tended to produce activated @entity1810 de novo. Anchorage-independent growth of cell lines that produced active @entity1810 was either stimulated, inhibited, or unaffected by @entity1810 . Cell lines that were inhibited by @entity1810 concurrently produced @entity18696 which was usually able to overcome the negative "autocrine" effect of @entity1810 . We conclude that both @entity18696 and @entity1810 , singly or in combination, are variously involved in the growth of transformed @entity35 liver epithelial cells. @entity18696 has a predominantly positive autocrine action on the growth of @entity35 liver @entity5 cell lines. The "paracrine" effect of @entity1810 may be at least as important as its autocrine effect in the growth of these transformed epithelial cell lines.
