Nα-Tosyl-l-phenylalanine Chloromethyl Ketone Induces Caspase-dependent Apoptosis in Transformed Human B Cell Lines with Transcriptional Down-regulation of Anti-apoptotic HS1-associated Protein X-1

• Published in: The Journal of biological chemistry Vol. 284; no. 41; pp. 27827 - 27837
• Main Authors: Jitkaew, Siriporn, Trebinska, Alicja, Grzybowska, Ewa, Carlsson, Göran, Nordström, Anders, Lehtiö, Janne, Fröjmark, Anne-Sophie, Dahl, Niklas, Fadeel, Bengt
• Format: Journal Article
• Language: English
• Published: 9650 Rockville Pike, Bethesda, MD 20814, U.S.A Elsevier Inc 09.10.2009; American Society for Biochemistry and Molecular Biology
• Subjects: Mechanisms of Signal Transduction
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.027912

Nα-Tosyl-l-phenylalanine chloromethylketone (TPCK) has been widely used to investigate signal transduction pathways that are involved in gene expression and cell survival/cell death. However, contradictory effects of TPCK on apoptosis have been reported, and the underlying signaling events leading to TPCK-induced promotion or prevention of apoptosis are not fully understood. Here, we show that TPCK induces caspase-dependent apoptosis in Epstein-Barr virus (EBV)-transformed human B cell lines with release of pro-apoptotic proteins from mitochondria. TPCK treatment also results in down-regulation of the anti-apoptotic proteins, cIAP1, cIAP2, and HAX-1, and caspase-dependent cleavage of the anti-apoptotic proteins, Bcl-2 and XIAP. Quantitative PCR analysis confirmed that the TPCK-induced down-regulation of HAX-1 occurred at the transcriptional level, and experiments using the specific pharmacological inhibitor, Bay 11-7082, suggested that HAX-1 expression is subject to regulation by the transcription factor, NF-κB. B cell lines derived from patients with homozygous HAX1 mutations were more sensitive to TPCK-induced apoptosis when compared with normal donor cell lines. Furthermore, N-acetylcysteine effectively blocked TPCK-induced apoptosis in EBV-transformed B cell lines and prevented the down-regulation or cleavage of anti-apoptotic proteins. Taken together, our studies demonstrate that TPCK induces apoptosis in human B cell lines and exerts multiple effects on pro- and anti-apoptotic factors.