Lymphocyte cytosolic protein 1 (LCP1) is a novel TRAF3 dysregulation biomarker with potential prognostic value in multiple myeloma

Chromosomal rearrangement involving 14q32 region that results in TNF receptor associated factor 3 (TRAF3) dysfunctional mutation is the most frequent NF-κB pathway mutation in multiple myeloma (MM). Subsequent NF-κB inducing Kinase (NIK) stabilization plays a critical role in alternative NF-κB activation. However, disease progression resulting from TRAF3 dysregulation has not been well understood. In this study, we identified lymphocyte cellular protein 1 (LCP1) as a novel NIK-driven alternative NF-κB target in TRAF3 dysfunctional mutation using RNA-seq, ChIP-seq (RelA/p65 and p52 NF-κB) and other validation methods. LCP1 is exclusively activated in MM cells with TRAF3 loss-of-function mutation. In MM patients, higher LCP1 expression was significantly pronounced in poor prognosis groups such as 4p16 and MAF. CD138 negative MM patient cells showed elevated LCP1 expression and inhibition of LCP1 can sensitize proteasome inhibitor bortezomib in TRAF3 mutant MM cells in vitro. We report that LCP1 is a NIK-driven biomarker in TRAF3 dysfunctional MM and targeting LCP1 can provide a valuable therapeutic intervention in TRAF3 mutated MM.