USP41 Enhances Epithelial–Mesenchymal Transition of Breast Cancer Cells through Snail Stabilization

Abstract

Ubiquitination, one of many post-translational modifications, causes proteasome-mediated protein degradation by attaching ubiquitin to target proteins. Multiple deubiquitinases inhibit the ubiquitination pathway by removing the ubiquitin chain from protein, thus contributing to the stabilization of substrates. USP41 contributes to invasion, apoptosis and drug resistance in breast and lung cancer cells. However, the detailed mechanism and role of USP41 in breast cancer have not been elucidated. USP41 was overexpressed and showed poor prognosis according to the aggressive phenotype of breast cancer cells. Knockdown of USP41 inhibited migration and growth of breast cancer cells, whereas overexpression of USP41 increased cell growth and migration. In addition, depletion of USP41 downregulated Snail protein expression, an epithelial–mesenchymal transition marker, but not mRNA expression. Furthermore, USP41 interacted with and inhibited ubiquitination of Snail, resulting in the increase in Snail stabilization. Therefore, these data demonstrated that USP41 increases migration of breast cancer cells through Snail stabilization.

Mechanisms of USP18 deISGylation revealed by comparative analysis with its human paralog USP41

“…Finally, since USP41 is not a second ISG15 protease, we aimed at characterizing which Ubl it controls in vivo. Despite a few reports stating that it is a deubiquitinating enzyme (DUB) 35,36 , we found that USP41 can regulate the Ubl FAT10 (HLA-F adjacent transcript 10), which presents similar features as ISG15. For instance, FAT10 structure is comprised of two ubiquitin-like molecules 37 , and its expression is induced by pro-inflammatory cytokines such as IFN-γ and tumor necrosis factor (TNF), while it is mostly restricted to cell types of the immune system 38 .…”

“…Overall, USP41 is a vastly uncharacterized protein whose biological function remains largely unknown, but it is predicted to exhibit deubiquitinating activity based on the presence of the typical catalytic triad domain including Cys, His and Asn residues common to all cysteine DUBs. It has been reported that USP41 promotes proliferation of lung cancer cells 51 , as well as in other cancerous cell lines, through regulating the deubiquitination of the receptor for activated C kinase 1 (RACK1) 35 and the epithelial-mesenchymal transition transcription factor (EMT-TF) Snail 36 . However, we failed to observe any reactivity of USP41 in vitro with a panel of activity-based probes, including ubiquitin (Figure 5A).…”