Nuclear factor inducing kinase: A key regulator in osteopontin-induced MAPK/I kappa B kinase dependent NF-kappa B-mediated promatrix metalloproteinase-9 activation

摘要

Osteopontin (OPN) is a secreted, non-collagenous, sialic-acid rich, glycosylated adhesive phospho-protein. Several highly metastatic transformed cells synthesized a higher level of OPN compared with non-tumorigenic cells. We have recently reported that OPN induces nuclear factor-kappa B (NF-kappa B)-mediated promatrix metalloproteinase-2 activation through I kappa B alpha/IKK signaling pathways. However, the molecular mechanism(s) by which OPN regulates pro-matrix metalloproteinase-9 (pro-MMP-9) activation and involvement of upstream kinases in regulation of these processes that ultimately control cell motility and tumor growth in murine melanoma cells are not well defined. Here we report that OPN induces alpha v beta 3 integrin-mediated phosphorylation and activation of nuclear factor inducing kinase (NIK) and enhances the interaction between phosphorylated NIK and I kappa B alpha kinase alpha/beta (IKK alpha/beta) in B16F10 cells. Moreover, NIK is involved in OPN-induced phosphorylations of MEK-1 and ERK1/2 in these cells. OPN induces NIK-dependent NF-kappa B activation through ERK/IKK alpha/beta-mediated pathways. Furthermore, OPN enhances NIK-regulated urokinase-type plasminogen activator (uPA) secretion, uPA-dependent pro-MMP-9 activation, and cell motility. Pretreatment of cells with anti-MMP-2 antibody along with anti-MMP-9 antibody drastically inhibited the OPN-induced cell migration and chemoinvasion, whereas cells pretreated with anti-MMP-2 antibody had no effect on OPN-induced pro-MMP-9 activation suggesting that OPN induces pro-MMP-2 and pro-MMP-9 activations through two distinct pathways. Taken together, NIK acts as crucial regulator in OPN-induced MAPK/IKK-mediated NF-kappa B-dependent uPA secretion and MMP-9 activation thereby controlling melanoma cell motility and chemoinvasion.