HUMAN AND BOVINE GRANULOCYTE CHEMOTACTIC PROTEIN-2 - COMPLETE AMINO-ACID-SEQUENCE AND FUNCTIONAL-CHARACTERIZATION AS CHEMOKINES

Tumor cells are capable of simultaneously producing a number of relate d inflammatory peptides, now classified as chemokines. We have isolate d a new human granulocyte chemotactic protein (GCP-2), coproduced with interleukin-8 (GCP-1/IL-8) by osteosarcoma cells. Furthermore, the bo vine homologue of human GCP-2 was purified from kidney tumor cells usi ng the same isolation procedure. Both chemokines occur in at least fou r NH2-terminally truncated forms. These 5-6-kDa proteins do not differ in potency and efficacy as granulocyte chemotactic factors using a st andard in vitro migration assay. The complete primary structures of hu man and bovine GCP-2 were disclosed by sequencing peptide fragments de rived from the natural proteins. On the basis of the conservation of f our cysteine residues, the two molecules are to be classified within t he C-X-C chemokine family, including IL-8. Human and bovine GCP-2 are 67% similar at the amino acid level. Their sequences show only weak si milarity with that of IL-8, and human GCP-2 does not cross-react in a radioimmunoassay for IL-8. Human and bovine GCP-2 are specific granulo cyte chemotactic factors in that they do not attract human monocytes. Bovine GCP-2 is not species specific since it is at least as active as human GCP-2 on human granulocytes. Both chemokines can also activate postreceptor mechanisms leading to release of gelatinase B by granuloc ytes. This is indicative for a possible role in inflammation and tumor cell invasion.