Nuclear expression of YB-1 in diffuse large B-cell lymphoma: correlation with disease activity and patient outcome

The aim of this study is to investigate the correlations among Y-box binding protein-1 (YB-1) and P-glycoprotein(P-gp) and their prognostic significance in diffuse large B-cell lymphoma (DLBCL). The expression of YB-1 and P-gp was examined immunohistochemically on 68 patients with DLBCL who were treated from 2003 to 2005. Samples were paraffin-embedded newly diagnosed DLBCL tissues taken from the surgical specimens before adjuvant chemotherapy. We determined the prognostic significance of YB-1 and its relationship with P-gp in patients with DLBCL. Of the 68 tumors examined, 42 (61.8%) were positive for YB-1 expression in the nucleus. The nuclear expression of YB-1 was significantly associated with clinical stages, bone marrow involvement, extra nodal involvement, and poor response to chemotherapy. No associations were observed between P-gp and clinical features, in context of the poor response to chemotherapy. Nuclear expression of YB-1 was correlated significantly with increased expression of P-gp patients with a nuclear YB-1 tumor had a poorer prognosis than did those with a cytoplasmic YB-1 tumor in all of the DLBCL patients (P = 0.035). Thus, correlation of YB-1 and P-gp emerged as a possible biomarker for unfavorable prognosis in DLBCL. It may provide useful information for clinicians to determine the appropriate therapy for each type of DLBCL.