title: Granzyme B leakage-induced apoptosis is a crucial mechanism of cell death in nasal-type NK/T-cell lymphoma.
abstract: This study aims to investigate the role of granzyme B in the apoptosis of nasal-type NK/T-cell lymphoma. Twenty-four nasal-type NK/T-cell lymphomas were examined by TdT-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labeling (TUNEL) assay and immunohistochemical staining for active caspase 3, poly(ADP-ribose) polymerase (PARP-1/p85)/p85, and Bcl-2. In addition, HANK-1 and NKL cell lines were analyzed using Western blot analysis. Immunoprecipitation was performed to identify the binding of granzyme B and intrinsic serpin proteinase inhibitor 9 (PI-9). To localize granzyme B, immunogold labeling and immunofluorescence staining were performed. The expression level of granzyme B in tumor tissue was correlated with the apoptosis rate (P=0.015), degree of necrosis (P=0.002), and the levels of active caspase 3 (P=0.036) and poly ADP-ribose polymerase (PARP)-1/p85 (P=0.040). The granzyme B-positive HANK-1 cell line showed increased spontaneous cell death compared to the granzyme B-negative NKL cell line. The untreated HANK-1 cells released cytochrome c into the cytosol with cleavage of caspase 3 and PARP-1. Treatment with granzyme B inhibitor and caspase inhibitor decreased the cleavage of PARP-1. By performing immunogold labeling, granzyme B was identified within the cytolytic granules as well as in the cytosol. Confocal microscopy and immunoprecipitation assays confirmed the colocalization of PI-9 and granzyme B, which formed an SDS-resistant complex. These results suggested that granzyme B leakage induces cell death in NK/T-cell lymphomas via both caspase-dependent and -independent mechanisms, and this leads to the extensive necrosis that is commonly seen in NK/T-cell lymphoma.
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. yhko@smc.samsung.co.kr
authors.forename: Young-Hyeh
authors.initials: YH
authors.lastname: Ko
authors.forename: Sanghui
authors.initials: S
authors.lastname: Park
authors.forename: Heekyung
authors.initials: H
authors.lastname: Jin
authors.forename: Heesook
authors.initials: H
authors.lastname: Woo
authors.forename: Hyunseop
authors.initials: H
authors.lastname: Lee
authors.forename: Chaewha
authors.initials: C
authors.lastname: Park
authors.forename: Kihyun
authors.initials: K
authors.lastname: Kim
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053804:Granzymes / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000276:immunology*; D016399:Lymphoma, T-Cell / Q000201:enzymology / Q000276:immunology / Q000473:pathology*; D008854:Microscopy, Electron; D009669:Nose Neoplasms / Q000201:enzymology / Q000276:immunology / Q000473:pathology*
chemical_list: D004791:Enzyme Inhibitors; D053804:Granzymes