Squamous cell carcinoma antigen 1 is an inhibitor of parasite-derived cysteine proteases

FEBS Lett. 2007 Sep 4;581(22):4260-4. doi: 10.1016/j.febslet.2007.07.072. Epub 2007 Aug 9.


The physiological significance of the squamous cell carcinoma antigens 1 (SCCA1) and SCCA2, members of the ovalbumin serpin family, remains unresolved. In this study, we examined whether SCCA1 or SCCA2 inhibits protozoa- or helminth-derived cysteine proteases. SCCA1, but not SCCA2, potently inhibited the cysteine protease activities of CPB2.8 from Leishmania mexicana, cruzain from Trypanosoma cruzi, rhodesain from Trypanosoma brucei rhodesience, and cathepsin L2 from Fasciola hepatica. The inhibitory activities of SCCA1 were due to its resistance to cleavage by the cysteine proteases. The findings indicate that induction of cysteine protease inhibitors might be a novel defense mechanism against parasite development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Neoplasm / chemistry
  • Antigens, Neoplasm / metabolism*
  • Catalysis
  • Cell Line
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / metabolism*
  • Humans
  • Keratinocytes / metabolism
  • Molecular Sequence Data
  • Parasites / enzymology*
  • Serpins / chemistry
  • Serpins / metabolism*
  • Structure-Activity Relationship


  • Antigens, Neoplasm
  • Cysteine Proteinase Inhibitors
  • Serpins
  • squamous cell carcinoma-related antigen
  • Cysteine Endopeptidases