The RCAN1 inhibits NF-κB and suppresses lymphoma growth in mice

Nuclear factor-kappa B (NF-kappa B) has a vital role in cell survival. Inhibition of NF-kappa B has been proven to be an efficient therapeutic pathway for various cancers. Activation of NF-kappa B is mainly through serine residues' phosphorylation of inhibitor of kappa B alpha (I kappa B alpha) by IKK complex. Phosphorylation at tyrosine 42 is an alternative pathway in regulation of I.Ba and NF-kappa B signaling, though little is known about the underlying mechanism. Here we identified regulator of calcineurin 1 (RCAN1) as a novel endogenous inhibitor of NF-kappa B signaling pathway. RCAN1 can interact with I kappa B alpha and affect the phosphorylation of I.Ba at tyrosine 42. Overexpression of RCAN1 by adenovirus reduced cell viability in lymphoma Raji cells and restrained the growth of lymphoma transplants in mice. We further found that N terminus 1-103aa of RCAN1 is sufficient to inhibit NF-kappa B and reduce cell viability of lymphoma cells. Our study implicated a novel therapeutic approach for lymphoma by RCAN1 through inhibition of NF-kappa B signaling.