Loss of bHLH transcription factor E2A activity in primary effusion lymphoma confers resistance to apoptosis

Abstract

Similar to classical Hodgkin lymphoma (HL) tumour cells, primary effusion lymphoma (PEL) originates from mature B cells but displays a non-B cell phenotype, the mechanisms and consequences of which are not yet understood. This study showed that PEL lacked DNA binding activity of the B cell-determining transcription factors E2A, EBF and Pax5. PEL overexpressed the E2A antagonists ABF-1 and Id2, which have been described to block the B-cell differentiation program in classical HL. However, in contrast to HL cells, B lineage-inappropriate genes were not similarly upregulated in PEL, and reconstitution of B cell-specific E2A homodimer activity in PEL induced apoptosis. These data demonstrate that lineage infidelity in PEL is not as pronounced as in HL, and that the loss of the B cell-specific transcription factor E2A in PEL is implicated in apoptosis protection. © 2007 The Authors.