Tumor-suppressor NFκB2 p100 interacts with ERK2 and stabilizes PTEN mRNA via inhibition of miR-494

Emerging evidence from The Cancer Genome Atlas has revealed that nuclear factor kappa B2 (nf kappa b2) gene encoding p100 is genetically deleted or mutated in human cancers, implicating NF kappa B2 as a potential tumor suppressor. However, the molecular mechanism underlying the antitumorigenic action of p100 remains poorly understood. Here we report that p100 inhibits cancer cell anchorageindependent growth, a hallmark of cellular malignancy, by stabilizing the tumor-suppressor phosphatase and tensin homolog (PTEN) mRNA via a mechanism that is independent of p100' s inhibitory role in NF kappa B activation. We further demonstrate that the regulatory effect of p100 on PTEN expression is mediated by its downregulation of miR-494 as a result of the inactivation of extracellular signal-regulated kinase 2 (ERK2), in turn leading to inhibition of c-Jun/ activator protein-1-dependent transcriptional activity. Furthermore, we identify that p100 specifically interacts with non-phosphorylated ERK2 and prevents ERK2 phosphorylation and nuclear translocation. Moreover, the death domain at C-terminal of p100 is identified as being crucial and sufficient for its interaction with ERK2. Taken together, our findings provide novel mechanistic insights into the understanding of the tumor-suppressive role for NF kappa B2 p100.