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Multiple forms of cathepsin b in human lung cancer

1995; Wiley; Volume: 61; Issue: 1 Linguagem: Inglês

10.1002/ijc.2910610109

1097-0215

E Kr̆epela, Jan Procházka, Helena Mynaříková, B Kárová, Jaroslav Poläk, Jan Čermák, H Roubková,

Peptidase Inhibition and Analysis

Abstract In this study we have examined, by means of isoelectric focusing (IEF) in native polyacrylamide gel and contact‐print fluorescence zymography, whether human lung carcinomas and the lung parenchyma contain different pools of multiple charge forms of the cysteine proteinase cathepsin B. The isoelectric point (pl) patterns of cathepsin B from lung carcinoma and matched lung were similar, particularly with regard to 2 major intermediate acidic enzyme pl forms designated as I and II (pl app of 5.10 and 4.93 in tumors, and 5.11 and 4.94 in lungs, respectively). The slightly acidic cathepsin B pl forms (pl app 5.47–5.19) in squamous‐cell lung carcinoma (SQCLC) were significantly more numerous than such enzyme pl forms in lungs. The numbers of the highly acidic cathepsin B pl forms (pl app 4.82–4.33) were significantly higher in SQCLC and lung adenocarcinoma (ACL) than in matched lung. The activity distribution percentage in the set of highly acidic cathepsin B pl forms was significantly higher in SQCLC and ACL than in matched lung. We also observed that cathepsin B from SQCLC and matched lung was fully recoverable by IEF from inhibition by leupeptin. Using the cysteine‐proteinase‐specific inactivator E‐64, we revealed by IEF that some cathepsin B isoforms (charge forms) from SQCLC were more resistant to inactivation by this compound than the corresponding enzyme isoforms from lungs. After IEF, the enzyme isoforms apparently lost their resistance to E‐64. Our results indicate that the pool of multiple charge forms of cathepsin B in SQCLC and ACL is different from that in the lung, and also that there may be an increased level of loose complexes between cathepsin B and some proteins or polypeptides in SQCLC compared to the lung. © 1995 Wiley‐Liss Inc .