CEP1612, a dipeptidyl proteasome inhibitor, induces p21WAF1 and p27KIP1 expression and apoptosis and inhibits the growth of the human lung adenocarcinoma A-549 in nude mice.
The ubiquitin proteasome system is responsible for the proteolysis of important cell cycle and apoptosis-regulatory proteins. In this paper we report that the dipeptidyl proteasome inhibitor, phthalimide-(CH2)8CH-(cyclopentyl) CO-Arg(NO2)-Leu-H (CEP1612), induces apoptosis and inhibits tumor growth of the human lung cancer cell line A-549 in an in vivo model. In cultured A-549 cells, CEP1612 treatment results in accumulation of two proteasome natural substrates, the cyclin-dependent kinase inhibitors p21WAF1 and p27KIP1, indicating its ability to inhibit proteasome activity in intact cells. Furthermore, CEP1612 induces apoptosis as evident by caspase-3 activation and poly(ADP-ribose) polymerase cleavage. Treatment of A-549 tumor-bearing nude mice with CEP1612 (10 mg/kg/day, i.p. for 31 days) resulted in massive induction of apoptosis and significant (68%; P < 0.05) tumor growth inhibition, as shown by terminal deoxynucleotidyltransferase-mediated UTP end labeling. Furthermore, immunostaining of tumor specimens demonstrated in vivo accumulation of p21WAF1 and p27KIP1 after CEP1612 treatment. The results suggest that CEP1612 is a promising candidate for further development as an anticancer drug and demonstrate the feasibility of using proteasome inhibitors as novel antitumor agents.
Sun
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Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, Department of Biochemistry and Molecular Biology, University of South Florida, Tampa 33612-9494, USA.
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D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000096:biosynthesis*; D004151:Dipeptides / Q000494:pharmacology*; D005260:Female; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis*; D010797:Phthalimides / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D023041:Xenograft Model Antitumor Assays
C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004151:Dipeptides; D006131:Growth Inhibitors; D008869:Microtubule-Associated Proteins; D010797:Phthalimides; D011480:Protease Inhibitors; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; C118004:CEP 1612