BCL2 overexpression in diffuse large B-cell lymphoma

Translocation (14;18)(q32;q21), which is detected in 20-30% of diffuse larg e B-cell lymphomas (DLBCL), is regarded as a major mechanism for BCL2 prote in overexpression. Nevertheless, BCL2 overexpression is not always caused b y t(14;18), because it is often detected in lymphomas without BCL2 rearrang ement. Recent studies have shown that increased expression of BCL2 may also result fi-om BCL2 gene amplification in DLBCL. Similarly, it has been spec ulated that the mutations of the open reading frame might cause increased e xpression of BCL2 by affecting the interactions of BCL2 with other proteins . The results obtained from studies on the association of BCL2 protein over expression with survival of DLBCL are controversial, although a correlation with decreased overall survival seems to exist. However, BCL2 rearrangemen t does not seem to have any major association with poor prognosis, but it i s difficult to assess its true impact on prognosis due to differences in tr eatment and follow-up, and methodologies applied to study the BCL2 rearrang ement. This review summarizes the BCL2 expression studies in DLBCL and disc usses the prognostic relevance of BCL2 overexpression and its mechanisms.