RelA NF-κB subunit activation as a therapeutic target in diffuse large B-cell lymphoma

It has been well established that nuclear factor kappa-B (NF-kappa B) activation is important for tumor cell growth and survival. RelA/p65 and p50 are the most common NF-kappa B subunits and involved in the classical NF-kappa B pathway. However, the prognostic and biological significance of RelA/p65 is equivocal in the field. In this study, we assessed RelA/p65 nuclear expression by immunohistochemistry in 487 patients with de novo diffuse large B-cell lymphoma (DLBCL), and studied the effects of molecular and pharmacological inhibition of NF-kappa B on cell viability. We found RelA/p65 nuclear expression, without associations with other apparent genetic or phenotypic abnormalities, had unfavorable prognostic impact in patients with stage I/II DLBCL. Gene expressionprofiling analysis suggested immune dysregulation and antiapoptosis may be relevant for the poorer prognosis associated with p65 hyperactivation in germinal center B-cell-like (GCB) DLBCL and in activated Bcell- like (ABC) DLBCL, respectively. We knocked down individual NF-kappa B subunits in representative DLBCL cells in vitro, and found targeting p65 was more effective than targeting other NF-kappa B subunits in inhibiting cell growth and survival. In summary, RelA/p65 nuclear overexpression correlates with significant poor survival in earlystage DLBCL patients, and therapeutic targeting RelA/p65 is effective in inhibiting proliferation and survival of DLBCL with NF-kappa B hyperactivation.