MLN4924, a novel protein neddylation inhibitor, suppresses proliferation and migration of human urothelial carcinoma: In vitro and in vivo studies

MLN4924, a small molecule inhibitor of NEDD8 activating enzyme (NAE), has been reported to elicit an anti-tumor effect on various malignancies. In this study, we investigated the anti-tumor effect of MLN4924 in human urothelial carcinoma (UC) in vitro and in vivo by using three human UC cell lines of various grading (T24, NTUB1 and RT4). The impact of MLN4924 on UC cells was determined by measuring viability (MTT), proliferation (BrdU incorporation), cell cycle progression (flow cytometry with propidium iodide staining) and apoptosis (flow cytometry with annexin V-FITC labeling). The cell cycle regulatory molecules, apoptosis-related molecules, and cell stress-related proteins were examined by Western blotting. The influence of tumor cell migration and invasion was analyzed by Transwell and wound healing assays. We also evaluated the effects of MLN4924 on tumor growth by a SCID xenograft mouse model. The data show that MLN4924 induced dose-dependent cytotoxicity, anti-proliferation, anti-migration, anti-invasion and apoptosis in human UC cells, accompanied by activations of Bad, phospho-histone H2A.X, caspase-3, 7 and PARP, decreased level of phospho-Bcl2, and caused cell cycle retardation at the G2M phase. Moreover, MLN4924 activated endoplasmic reticulum stress-related molecules (caspase-4, phospho-eIF2α, ATF-4 and CHOP) and other stress responses (JNK and c-Jun activations). Finally, we confirmed MLN4924 inhibited tumor growth in a UC xenograft mouse model with minimal general toxicity. We concluded that MLN4924 induces apoptosis and cell cycle arrest, as well as activation of cell stress responses in human UC. These findings imply MLN4924 provides a novel strategy for the treatment of UC.