Bioactive murine and human interleukin-12 fusion proteins which retain antitumor activity in vivo

Nat Biotechnol. 1997 Jan;15(1):35-40. doi: 10.1038/nbt0197-35.


Interleukin-12 (IL-12) is unique amongst cytokines in being a disulfide-linked heterodimer of two separately encoded subunits (p35 and p40). We expressed single chain IL-12 proteins from retroviral constructs in which the two IL-12 subunits were linked by a 6-15 amino acid polypeptide linker, with deletion of the 22 amino acid leader sequence of the trailing subunit. The murine fusion protein p35 containing a (Gly4Ser)3 linker was stably expressed, bioactive in vitro, and had an apparent specific activity comparable to that of native and recombinant IL-12. Western blotting confirmed that murine p35 retained the linking polypeptide sequences. The analogous human p35 fusion protein containing a Gly6Ser linker was bioactive with an apparent specific activity comparable to recombinant human IL-12. In a preexisting CMS-5 tumor model, CMS-5 cells secreting either native or fusion protein forms of IL-12 prolonged survival and led to complete tumor regression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antineoplastic Agents / pharmacology*
  • Base Sequence
  • Blotting, Western
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor / methods
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Fibrosarcoma / drug therapy
  • Fibrosarcoma / genetics
  • Fibrosarcoma / pathology
  • Genetic Vectors / genetics
  • Humans
  • Interleukin-12 / biosynthesis
  • Interleukin-12 / genetics*
  • Interleukin-12 / pharmacology*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Recombinant Fusion Proteins / biosynthesis*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / pharmacology*
  • Retroviridae / genetics
  • Transfection
  • Tumor Cells, Cultured


  • Antineoplastic Agents
  • Recombinant Fusion Proteins
  • Interleukin-12