Bcl-2, Bcl-X, Bax, and Bak expression in short- and long-lived patients with diffuse large B-cell lymphomas.
Long-term cure is now possible for approximately 50% of all patients with aggressive non-Hodgkin's lymphoma (NHL). Apoptosis-related proteins play an important role in the chemosensitivity or chemoresistance of tumors. We examined the role of Bcl-2 family proteins in aggressive NHL. We retrospectively selected two groups of patients by clinical outcome: 24 patients with chemoresponsive disease and long survival (median, 88 months); and 20 patients with chemoresistant disease and short survival (median, 8 months). The expression of the apoptosis-regulating proteins, Bcl-2, Bcl-X, Bax, and Bak, in the initial biopsy samples was examined with immunohistochemical methods. Specimens containing >10% immunostained tumor cells were considered immunopositive. An inverse association was found between length of patient survival and expression of Bcl-2, Bcl-X, and Bax. Bcl-2 was expressed in 75% of short-lived patients but in only 42% of the long-lived ones (P = 0.026). Bcl-X expression was also higher in the short-lived patients (40% versus 12.5%; P = 0.036). Unexpectedly, Bax expression was strongly associated with short survival (60% versus 21%; P = 0.008). Several combinations of protein expression, i.e., Bcl-2 with Bax, Bcl-2 with Bcl-X, and Bcl-X with Bax, were different between the groups: a positive expression of these proteins was found in the short-lived patients. Furthermore, a strong association was found between the expression of Bcl-2 and Bcl-X, suggesting that Bcl-X potentiates rather than replaces the effect of Bcl-2 in NHL. In diffuse large B-cell NHL, Bcl-2, Bcl-X, and Bax expression alone or in combination is associated with chemoresistance and shortterm survival.
Bairey
O
O
Felsenstein Medical Research Center, Sackler Faculty of Medicine, Tel Aviv University, Israel.
Zimra
Y
Y
Shaklai
M
M
Okon
E
E
Rabizadeh
E
E
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016393:Lymphoma, B-Cell / Q000378:metabolism* / Q000401:mortality; D016403:Lymphoma, Large B-Cell, Diffuse / Q000378:metabolism* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis*; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein