Effect of inhibitors of cysteine and serine proteases in anticancer drug-induced apoptosis in gastric cancer cells
Activation of proteases can play an important role in apoptotic cell death induced by anticancer drugs. To assess involvement of activation of cysteine and serine proteases in anticancer drug-induced apoptosis, we tested effect of inhibitors of cysteine and serine proteases on sensitivity to anticancer drugs in MKN45 gastric cancer cells. Cytotoxic effect by adriamycin (ADM), SN-38 (active form of irrinotecan) and cisplatin (CDDP) was significantly prevented by cotreatment with Z-Val-Ala-Asp-fluoromethylketone (Z-VAD-fmk) (p<0.01), a pancaspase inhibitor compared with drug alone using MTT assay. In contrast, cotreatment with N-acetyl-Tyr-Val-Ala-Asp aldehyde (AC-YVAD-CHO), a caspase 1 inhibitor did not prevent any cytotoxic effect of these drugs. Cotreatment of N-acetyl-Asp-Glu-Val-Asp aldehyde (AC-DEVD-CHO), a caspase 3 inhibitor prevented cytotoxic effect of VP-16 and SN-38 (p<0.01). Prevention of these cytotoxic effects by caspase inhibitors was not dose-dependent. Cotreatment of N-tosyl-L-lysyl chloromethylketone (TLCK), a serine protease inhibitor significantly prevented cytotoxic effect of ADM, SN-38, 5-fluorouracil (5-FU) and CDDP in a slight dose-dependent manner (p<0.01) except for etoposide (VP-16) and docetaxel (TXT), while an other serine protease inhibitor, N-tosyl-L-phenylalanyl chloromethylketone (TPCK) did not prevent any anticancer drug-induced cytotoxic effect. These effects were associated with prevention of internucleosomal DNA ladder formation in apoptosis. Further, protease inhibitors did not block induction of cytochrome c, that can explain the partial effect of prevention by anticancer-induced cell death. These results suggest that anticancer drug-induced cytotoxic effect is mediated by activation of serine protease (caspase-independent) as well as caspase-dependent pathway leading to apoptotic cell death, and that protease-independent pathway may also be involved in apoptotic pathways. The involvement of protease in signal transduction pathways may differ in cytotoxic action of drugs in gastric cancer cells.
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Document Type: Research Article
Affiliations: Department of Surgical Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
Publication date: June 1, 2001
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- The International Journal of Oncology provides an international forum for the publication of the latest, cutting-edge research in the broad area of oncology and cancer treatment. The journal accepts original high quality works and reviews on all aspects of oncology research including carcinogenesis, metastasis, epidemiology, chemotherapy and viral oncology. Through fair and efficient peer review, the journal is dedicated to publishing top tier research in the field, offering authors rapid publication as well as high standards of copy-editing and production. The International Journal of Oncology is published on a monthly basis in both print and early online.
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