title: Mitogenic effects of coagulation factor XII and factor XIIa on HepG2 cells.
abstract: The structure of coagulation factor XII (Hageman factor), inferred from its DNA sequence, includes two epidermal growth factor (EGF)-homologous domains in its amino-terminal region. This suggests that factor XII may exhibit EGF-like activities. Reciprocal antigenic cross-reactivity between factor XII and EGF was shown by exposing purified human factor XII or mouse EGF to anti-mouse EGF or anti-human factor XII. Western blot analysis showed that anti-mouse EGF recognized intact factor XII at 80 kDa. Together, these results suggest that the EGF-homologous domains are accessible for anti-EGF binding in native factor XII. To determine whether factor XII has mitogenic activity, HepG2 or L cells (10(4) cells per well) were grown in serum-free medium in the presence or absence of factor XII or kaolin-activated factor XII (factor XIIa). Both factors XII and XIIa (6.0 micrograms/ml) enhanced cell proliferation by approximately 2-fold (P less than 0.001 and P less than 0.005, respectively). In contrast, L cells, which are not EGF target cells, were not affected by either factor XII or factor XIIa. Various doses of factor XII enhanced cell proliferation, [3H]thymidine incorporation, and [3H]leucine incorporation in HepG2 cells cultured under the same conditions. These data indicate that factor XII, like EGF, is a mitogen for HepG2 cells and suggest a possible autocrine role in the liver.
authors.affiliation: Division of Hematology-Oncology, Childrens Hospital of Los Angeles, University of Southern California 90027.
authors.forename: K T
authors.initials: KT
authors.lastname: Schmeidler-Sapiro
authors.forename: O D
authors.initials: OD
authors.lastname: Ratnoff
authors.forename: E M
authors.initials: EM
authors.lastname: Gordon
mesh_terms: D000906:Antibodies / Q000494:pharmacology; D000941:Antigens / Q000276:immunology; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000276:immunology; D005174:Factor XII / Q000276:immunology / Q000494:pharmacology*; D015956:Factor XIIa / Q000494:pharmacology*; D006801:Humans; D007739:L Cells / Q000166:cytology; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology*; D008934:Mitogens; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D000941:Antigens; D008934:Mitogens; D004815:Epidermal Growth Factor; D005174:Factor XII; D004247:DNA; D015956:Factor XIIa