Interleukin-20 Promotes Migration of Bladder Cancer Cells through Extracellular Signal-regulated Kinase (ERK)-mediated MMP-9 Protein Expression Leading to Nuclear Factor (NF-κB) Activation by Inducing the Up-regulation of p21WAF1 Protein Expression *

The role of interleukin-20 in tumor migration remains to be elucidated. Results: IL-20 induces cell migration via ERK1/2-mediated NF-B/MMP-9 regulation by inducing p21 WAF1 expression. Conclusion: p21 WAF1 is essential for the cell migration induced by IL-20. Significance: This work provides novel insights into the molecular events of IL-20-mediated cancer cell migration indicating it is dependent on p21 WAF1 expression. The role of inflammatory cytokine interleukin-20 (IL-20) has not yet been studied in cancer biology. Here, we demonstrated up-regulation of both IL-20 and IL-20R1 in muscle-invasive bladder cancer patients. The expressions of IL-20 and IL-20R1 were observed in bladder cancer 5637 and T-24 cells. We found that IL-20 significantly increased the expression of matrix metalloproteinase (MMP)-9 via binding activity of NF-B and AP-1 in bladder cancer cells and stimulated the activation of ERK1/2, JNK, p38 MAPK, and JAK-STAT signaling. Among the pathways examined, only ERK1/2 inhibitor U0126 significantly inhibited IL-20-induced migration and invasion. Moreover, siRNA knockdown of IL-20R1 suppressed migration, invasion, ERK1/2 activation, and NF-B-mediated MMP-9 expression induced by IL-20. Unexpectedly, the cell cycle inhibitor p21 WAF1 was induced by IL-20 treatment without altering cell cycle progression. Blockade of p21 WAF1 function by siRNA reversed migration, invasion, activation of ERK signaling, MMP-9 expression, and activation of NF-B in IL-20-treated cells. In addition, IL-20 induced the activation of IB kinase, the degradation and phosphorylation of IB, and NF-B p65 nuclear translocation, which was regulated by ERK1/2. IL-20 stimulated the recruitment of p65 to the MMP-9 promoter region. Finally, the IL-20-induced migration and invasion of cells was confirmed by IL-20 gene transfection and by addition of anti-IL-20 antibody. This is the first report that p21 WAF1 is involved in ERK1/2-mediated MMP-9 expression via increased binding activity of NF-B, which resulted in the induction of migration in IL-20/IL-20R1 dyad-induced bladder cancer cells. These unexpected results might provide a critical new target for the treatment of bladder cancer.