Ubiquitin C-terminal hydrolase-L1 increases cancer cell invasion by modulating hydrogen peroxide generated via NADPH oxidase 4

This study explored the role of ubiquitin C-terminal hydrolase-L1 (UCH-L1) in the production of ROS and tumor invasion. UCH-L1 was found to increase cellular ROS levels and promote cell invasion. Silencing UCH-L1, as well as inhibition of H(2)O(2) generation by catalase or by DPI, a NOX inhibitor, suppressed the migration potential of B16F10 cells, indicating that UCH-L1 promotes cell migration by up-regulating H(2)O(2) generation. Silencing NOX4, which generates H(2)O(2), with siRNA eliminated the effect of UCH-L1 on cell migration. On the other hand, NOX4 overexpressed in HeLa cells happens to be ubiquitinated, and NOX4 following deubiquitination by UCH-L1, restored H(2)O(2)-generating activity. These in vitro findings are consistent with the results obtained in vivo with catalase (−/−) C57BL/6J mice. When H(2)O(2) and UCH-L1 levels were independently varied in these animals, the former by infecting with H(2)O(2)-scavenging adenovirus-catalase, and the latter by overexpressing or silencing UCH-L1, pulmonary metastasis of B16F10 cells overexpressing UCH-L1 increased significantly in catalase (−/−) mice. In contrast, invasion did not increase when UCH-L1 was silenced in the B16F10 cells. These findings indicate that H(2)O(2) levels regulated by UCH-L1 are necessary for cell invasion to occur and demonstrate that UCH-L1 promotes cell invasion by up-regulating H(2)O(2) via deubiquitination of NOX4.