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Hepatic fibrosis is associated with the activation of stellate cells (HSCs), the major source of extracellular matrix (ECM) proteins. Transforming growth factor-beta (TGF-beta), signaling via Smad3, is the most profibrogenic cytokine and the major promoter of ECM synthesis. Halofuginone, an inhibitor of liver fibrosis, inhibits TGF-beta-dependent Smad3 phosphorylation in human HSCs in culture. We have used transcriptional profiling to evaluate the effect of halofuginone on gene expression during the progression of thioacetamide (TAA)-induced liver fibrosis in the rat and have focused on genes that are associated with TGF-beta. TAA treatment causes alterations in the expression of 7% of liver genes. Halofuginone treatment prevents the changes in the expression of 41% of these genes and results in the inhibition of HSC activation and collagen synthesis. During the early stages of the disease, halofuginone affects genes involved in alcohol, lipid, protein, and phosphate metabolism and cell adhesion and, at later stages, in the cell cycle (cell development, differentiation, cell proliferation, and apoptosis). The activation of TGF-beta-dependent genes, such as tartrate-resistant acid phosphatase, its putative substrate osteopontin, stellate cell activation-association protein, and fibrillin-1, during chemically induced fibrosis is prevented by halofuginone. This study thus highlights the role of TGF-beta signaling in liver fibrosis and especially its potential for pharmacological intervention. Halofuginone, which has demonstrated efficacy and tolerance in animals and humans, could become an effective and novel therapy for liver fibrosis.

The complete 1,210-amino acid sequence of the human epidermal growth factor (EGF) receptor precursor, deduced from cDNA clones derived from placental and A431 carcinoma cells, reveals close similarity between the entire predicted v-erb-B mRNA oncogene product and the receptor transmembrane and cytoplasmic domains. A single transmembrane region of 23 amino acids separates the extracellular EGF binding and cytoplasmic domains. The receptor gene is amplified and apparently rearranged in A431 cells, generating a truncated 2.8-kilobase mRNA which encodes only the extracellular EGF binding domain.

Sixteen hybridoma-derived antibodies to the epidermal growth factor receptor of A431 cells were studied with respect to their reactions with blood group-related carbohydrate structures. Twelve of these were assessed as recognizing carbohydrate determinants on the basis of their immunostaining of reference blood group substances on nitrocellulose paper. Three of these antibodies were further investigated by inhibition of binding assays with glycoproteins and structurally defined oligosaccharides or by haemagglutination of erythrocytes before and after treatment with endo-beta-galactosidase. Two of the antibodies, 29.1 and 455, were shown to have blood group A-related specificities which differed from one another and from those of monoclonal anti-A antibodies described previously. The third antibody, 3C1B12, which was shown to recognize a determinant based on alpha 1----3 fucosylated Type 2 chains on linear and branched backbone sequences, also differs from previously described monoclonal antibodies of 3-fucosyl-N-acetyllactosamine type, such as anti-SSEA-1 (anti-mouse embryo) and several antibodies to human myeloid cells. While these antibodies are invaluable in providing structural information on the carbohydrate chains of the receptor glycoprotein and should help to elucidate their functions, their use as 'anti-receptor' reagents in cell biology will be influenced by the knowledge that the determinants they recognize are shared by other glycoproteins and glycolipids of diverse cell types.