Abstract
Interleukin (IL)-28A, also called IFN-λ2, is a member of the classIIcytokine family and has demonstrated anti-proliferative and anti-viral signals. The present study demonstrated migration inducement of IL-28A-treated bladder cancer cells - a novel function. RNA microarray analysis showed an enhanced expression of IL-28A and its receptor IL-28AR1 in muscle invasive urothelial carcinoma in a human bladder. Strong expression of IL-28A and IL-28AR1 was detected in bladder cancer tissues and cell lines (5637, T-24, and HT1376 cells), as determined by real-time PCR and immunoblot analysis. IL-28A treatment induced migration of bladder cancer cells, independent of the cell growth. IL-28AR1-specific small interfering RNA (si-IL-28AR1) inhibited the induction of migration in IL-28A-treated cells. IL-28A treatment stimulated the expression of matrix metalloproteinases-9 (MMP-9) via activation of transcription factor NF-κB. Gene knockdown for MMP-9 and the p65 subunit of NF-κB, using siRNA transfection, suppressed wound healing migration in IL-28A-treated bladder cancer cells. Also, treatment with IL-28A induced activation of mitogen-activated protein kinase (MAPK) in bladder cancer cells. MAPK function blockage by a MAPK-specific inhibitor showed that MAPK phosphorylation is required for IL-28A-induced MMP-9 expression through activation of NF-κB. The transient transfection of bladder cancer cells with ERK1/2 knock down (si-ERK1/2) and dominant negative p38 (DNp38) suppressed IL-28A-induced migration. IL-28A-induced induction of MMP-9 expression, MAPK activation, and DNA binding activity of NF-κB was abolished in the presence of IL-28A neutralizing antibody or by transfection of si-IL-28AR1. These results show that IL-28A/IL-28AR1 dyad-induced wound healing migration requires NF-κB-mediated MMP-9 expression by MAPK activation.