N<sup>α</sup>-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

Siriporn JitkaewAlicja TrebinskaEwa GrzybowskaGöran CarlssonAnders NordströmJanne LehtiöAnne Sophie FröjmarkNiklas DahlBengt FadeelKarolinska University HospitalMahidol UniversityThe Institute of Science and Technology for Research and Development, Mahidol UniversityInstitute of Oncology, WarsawUniversity of Uppsala Rudbeck Laboratory2018-09-132018-09-132009-10-09Journal of Biological Chemistry. Vol.284, No.41 (2009), 27827-278371083351X002192582-s2.0-70350435090https://repository.li.mahidol.ac.th/handle/20.500.14594/27133Nα-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-αB. 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 EBVtransformed 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. © 2009 by The American Society for Biochemistry and Molecular Biology, Inc.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyN<sup>α</sup>-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-1ArticleSCOPUS10.1074/jbc.M109.027912