Stefin B, the major low molecular weight inhibitor in ovarian carcinoma

Cancer Lett. 1994 Jul 15;82(1):81-8. doi: 10.1016/0304-3835(94)90149-x.


Endogenous cysteine proteinase inhibitors (CPIs) presumably regulate lysosomal cysteine endopeptidases (CPs), such as cathepsins B and L, in vivo. An imbalance between CPs and CPIs in carcinomas, possibly due to impaired inhibition of proteinases, was reported. Ovarian carcinoma contain high levels of Stefin B and about twentyfold less Stefin A compared to normal epithelial tissue. Stefin B was isolated and characterized. We used alkaline treatment, affinity chromatography on Cm-papain Sepharose, followed by gel filtration and ion-exchange chromatography and anti-Stefin B-Sepharose 4B to isolate two major isoforms of Stefin B with pI values 5.9 and 6.5. M(r) of ovarian Stefin B was close to 14,000 as judged by SDS-PAGE and had a blocked N-terminus. It strongly inhibited papain (Ki = 0.11 nM) and cathepsin L (Ki = 0.035 nM), but only moderately cathepsin B (Ki = 130 nM). As these properties are similar to Stefin B from human and bovine origin, as well as to Stefin B from human histiosarcoma, we believe that tumor Stefin B does not differ from normal Stefin B.

MeSH terms

  • Chromatography, Affinity
  • Chromatography, High Pressure Liquid
  • Cystatin A
  • Cystatin B
  • Cystatins / isolation & purification
  • Cystatins / metabolism*
  • Cysteine Proteinase Inhibitors / metabolism*
  • Female
  • Humans
  • Isoelectric Focusing
  • Ovarian Neoplasms


  • CSTB protein, human
  • Cystatin A
  • Cystatins
  • Cysteine Proteinase Inhibitors
  • CSTA protein, human
  • Cystatin B