BCL-2 family proteins in peripheral T-cell lymphomas: correlation with tumour apoptosis and proliferation.
The present study investigated expression levels of the anti-apoptotic proteins BCL-2, BCL-XL and MCL-1 and the pro-apoptotic proteins BAX and BCL-XS in a series of 112 peripheral T-cell lymphomas (PTCLs) classified according to the WHO classification. Using immunohistochemical methods and a 10% cut-off, each protein was detected in a subset of PTCLs: BCL-2 in 46%, BCL-XS in 49%, BAX in 57%, BCL-XL in 57%, and MCL-1 in 65%. The mean percentage of positive cells for these proteins varied significantly among the PTCL types. Only two types of PTCL, ALK-positive anaplastic large cell lymphoma (ALCL) and enteropathy-type T-cell lymphoma, had a distinctive pattern of expression; all were BCL-2-negative and MCL-1-positive. The mean percentage of BAX-positive and BCL-XS-positive tumour cells was higher in ALK-positive ALCL than in ALK-negative ALCL or other types of PTCL (p = 0.06 and p = 0.01, respectively, Kruskal-Wallis test). MCL-1 was detected significantly more frequently (p = 0.01, chi-square test) and at higher levels (p = 0.0001, Kruskal-Wallis test) in ALK-positive ALCL and ALK-negative ALCL than in other PTCL types. The apoptotic rate, evaluated by the TUNEL assay, correlated inversely with BCL-2 expression (p = 0.035). The proliferation index, assessed by the MIB-1 antibody, correlated with expression levels of MCL-1 (R = 0.42, p = 0.003), BCL-2 (R = 0.32, p = 0.027), BAX (R = 0.33, p = 0.014), and BCL-XL (R = 0.34, p = 0.015) (Spearman rank). In conclusion, BCL-2 family proteins are expressed by a subset of PTCLs and their levels correlate with some histological types, apoptotic rate, and proliferation index. Expression of these proteins may explain the poor response of many types of PTCL to standard chemotherapy. These proteins may also provide novel targets for experimental therapy.
Rassidakis
George Z
GZ
Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Jones
Dan
D
Lai
Raymond
R
Ramalingam
Preetha
P
Sarris
Andreas H
AH
McDonnell
Timothy J
TJ
Medeiros
L Jeffrey
LJ
D000077548:Anaplastic Lymphoma Kinase; D017209:Apoptosis; D002455:Cell Division; D006801:Humans; D016411:Lymphoma, T-Cell, Peripheral / Q000378:metabolism* / Q000473:pathology; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism; D040081:Protein Array Analysis / Q000379:methods; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C000626173:ALK protein, human; D000077548:Anaplastic Lymphoma Kinase; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases