title: Expression of AIF and HtrA2/Omi in small lymphocytic lymphoma and diffuse large B-cell lymphoma.
abstract: BACKGROUND
  The pathogenesis of non-Hodgkin lymphoma may involve deregulation of apoptosis. In response to apoptotic stimuli, several proapoptotic proteins are released into the cytoplasm from the mitochondria, including second mitochondria-derived activator of caspases/direct inhibitor of apoptosis protein binding protein with low p I (Smac/DIABLO), apoptosis-inducing factor (AIF), and high temperature requirement protein A2 (HtrA2/Omi). Apoptosis-inducing factor promotes apoptosis through a caspase-independent pathway, while Smac/DIABLO and HtrA2/Omi do so through both caspase-dependent and caspase-independent pathways. Smac/DIABLO was reported to be strongly positive in diffuse large B-cell lymphoma (DLBCL) and virtually absent in small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL). Little is known about the expression of AIF and HtrA2/Omi in lymphomas.
  
  
  OBJECTIVE
  To evaluate the expression of AIF and HtrA2/Omi in SLL and DLBCL.
  
  
  METHODS
  Twenty-three DLBCLs, 20 SLLs/CLLs, and 10 benign lymph nodes were evaluated for AIF and HtrA2/Omi expression by immunohistochemical staining.
  
  
  RESULTS
  Apoptosis-inducing factor was strongly and diffusely expressed in 19 of 23 (83%) cases of DLBCL with comparable expression pattern between germinal center-like and non-germinal center-like subgroups. Apoptosis-inducing factor was weakly positive in 15 of 20 (75%) cases of SLL/CLL with increased intensity in pseudofollicles. In contrast, HtrA2/Omi was weakly expressed in SLL/CLL (17 of 20; 85%) and DLBCL (18 of 23; 78%).
  
  
  CONCLUSIONS
  The different expression level and pattern of AIF and HtrA2/Omi in SLL/CLL and DLBCL may suggest different apoptotic mechanisms involved in the pathogenesis and prognosis of these diseases. HtrA2/Omi does not appear to be a major player in the regulation of apoptosis of DLBCL and SLL/CLL.
authors: Department of Pathology, University of Alabama at Birmingham Health System, Birmingham, USA. shaoyingli2004@yahoo.com
authors: Shaoying
authors: S
authors: Li
authors: Mei
authors: M
authors: Wan
authors: Xu
authors: X
authors: Cao
authors: Yongsheng
authors: Y
authors: Ren
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D005260:Female; D000074923:High-Temperature Requirement A Serine Peptidase 2; D006801:Humans; D007150:Immunohistochemistry; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism*; D008198:Lymph Nodes / Q000378:metabolism; D016403:Lymphoma, Large B-Cell, Diffuse / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D024101:Mitochondrial Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism*
chemical_list: D051033:Apoptosis Inducing Factor; D024101:Mitochondrial Proteins; D012697:Serine Endopeptidases; C000615914:HTRA2 protein, human; D000074923:High-Temperature Requirement A Serine Peptidase 2