Squamous cell carcinoma antigen is a potent inhibitor of cysteine proteinase cathepsin L.
A squamous cell carcinoma antigen (SSCA), which is a member of the serpin family of proteinase inhibitors, was purified from sera of cancer patients. It did not inhibit serine proteinases. However, it non-competitively inhibited human cathepsin L with a Ki of 0.064 nM, but not cathepsins B and H among cysteine proteinases. These results indicated that SCCA is a non-functional serpin that inhibits cathepsin L in cancer cells.
Department of Clinical Pathology, Showa University Fujigaoka Hospital, Showa University School of Medicine, Yokohama-shi, Japan.
A
A
Takeda
T
T
Yamamoto
Y
Y
Nakamura
T
T
Takahashi
T
T
Hibino
D000818:Animals; D000951:Antigens, Neoplasm / Q000097:blood / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000276:immunology; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D002846:Chromatography, Affinity; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D005260:Female; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms / Q000276:immunology; D011480:Protease Inhibitors / Q000494:pharmacology*; D015843:Serpins; D013552:Swine; D002583:Uterine Cervical Neoplasms / Q000276:immunology
D000951:Antigens, Neoplasm; D011480:Protease Inhibitors; D015843:Serpins; C051072:squamous cell carcinoma-related antigen; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L