IL-1β induces urokinse- plasminogen activator expression and cell migration through PKCα, JNK1/2, and NF-κB in A549 cells

Breakdown of the extracellular matrix (ECM) is accomplished by the concerted action of several proteases, including the urokinase plasminogen-activator (uPA) system and matrix metalloproteinases (MMPs), which is crucial for cancer invasion and metastasis. Several reports have shown that the levels of IL-1 β and MMPs in plasma of the patients with lung cancer are significantly elevated and linkto the invasion of tumor cells. Therefore, we investigated whether IL-1 β-induced expression of uPA participated in lung cancer progression. In this study, IL-1 β significantly induced uPA expression and activity via PKCα-dependent JNK1/2 and NIK cascades, linking to IKKa/b activation, p65 translocation and transcription activity, using pharmacological inhibitors and transfection with dominant negative mutants and siRNAs. IL-1 β-induced uPA protein and mRNA expression in a time- and concentration-dependent manner, which was inhibited by pretreatment with the inhibitors of JNK1/2 (SP600125), PKC (Ro31-8220, Gö6976), or NF-kB (helenalin), and transfection with dominant negative mutants of PKCα, NIK, and IKKβ, and siRNAs ofJNK1/2 and p65. IL-1β stimulated PKCα translocation to plasma membrane leading to phosphorylation of JNK1/2, which was attenuated by PKC inhibitors and transfection with shRNAs of JNK1/2, but not by helenalin. In addition, IL-1 β stimulated p65 phosphorylation and translocation into nucleus concomitant with κBα phosphorylation and I κBα degradation, which was mediated via activation of PKCα-dependent JNK1/2-NIK/IKKβ cascade. These results demonstrated that in A549 cells, activation of p50/p65 heterodimer through sequential activation of PKCα-JNK-NIK-IKKβ -NF-κB was required for IL-1 β-induced uPA expression associated with migration of tumor cells.