In leukaemic CD5+ B cells the expression of BCL-2 gene family is shifted toward protection from apoptosis.
This study further investigated the mechanisms that control apoptosis in leukaemic CD5+ B cells, and focused on the Bcl-2 gene family. The pattern of expression of Bcl-2, Bcl-xL, Bcl-xS and Bax genes, selected because of their interrelated role in the control of apoptosis, was analysed in a series of CD5+ B-cell chronic lymphoid leukaemias. Cells from 34 patients with chronic lymphoid leukaemia of B-cell type (23 B-chronic lymphocytic leukaemia (B-CLL) and 11 mantle cell lymphoma (MCL) in leukaemic phase) were investigated. High levels of Bcl-2 mRNA were observed by Northern blot and high levels of Bcl-2 protein were detected by cytofluorograph analysis with a specific monoclonal antibody (MAb) in all cases. Strong Bax expression was detected by RT-PCR in 20/23 B-CLL cases; Bax was also observed in 8/11 MCL in leukaemic phase with variable degree of intensity. In both B-CLL and MCL samples the presence of Bax protein was confirmed by cytofluorograph analysis. RT-PCR detected high levels of Bcl-xL in 16/23 B-CLL and in 8/11 MCL in leukaemic phase, whereas Bcl-xS was detectable in low to trace amounts respectively in 13/23 B-CLL and in 6/11 MCL in leukaemic phase. According to the functional role of Bcl-2, Bcl-xL, Bcl-xS and Bax, these data indicate that the pattern of Bcl-2 family genes expression in leukaemic CD5+ B cells is skewed toward prevention of apoptosis and may thus favour the relentless accumulation of CD5+ leukaemic B cells.
Gottardi
D
D
Dipartimento di Scienze Biomediche e Oncologia Umana, Università di Torino, Italy.
Alfarano
A
A
De Leo
A M
AM
Stacchini
A
A
Aragno
M
M
Rigo
A
A
Veneri
D
D
Zanotti
R
R
Pizzolo
G
G
Caligaris-Cappio
F
F
D017209:Apoptosis; D001402:B-Lymphocytes / Q000378:metabolism*; D015152:Blotting, Northern; D018956:CD5 Antigens / Q000378:metabolism; D005434:Flow Cytometry; D015870:Gene Expression; D019254:Genes, bcl-2; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism*; D008228:Lymphoma, Non-Hodgkin / Q000378:metabolism*; D016133:Polymerase Chain Reaction
D018956:CD5 Antigens