Regulation of Hippo/YAP Axis in Colon Cancer Progression by the Deubiquitinase JOSD1

Abstract

Colon cancer is a prevalent malignancy, while recent studies revealed the dys-regulation of Hippo signaling as the important driver for colon cancer progression. Several studies have indicated that post-translational modifications on YAP play crucial roles in both Hippo signaling activity and cancer progression. This raises a puzzling question about why YAP/TAZ, an auto-inhibitory pathway, is frequently over-activated in colon cancer, despite the suppressive cascade of Hippo signaling remaining operational. The protein stability of YAP is subject to a tiny balance between ubiquitination and deubiquitination processes. Through correlation analysis of DUBs (deubiquitinases) expression and Hippo target gene signature in colon cancer samples, we found JOSD1 as a critical deubiquitinase for Hippo signaling and colon cancer progression. JOSD1 could facilitate colon cancer progression and in colon cancer, inhibition of JOSD1 via shRNA has been demonstrated to impede tumorigenesis. Furthermore, molecular mechanism studies have elucidated that JOSD1 enhances the formation of the Hippo/YAP transcriptome by impeding K48-linked polyubiquitination on YAP. ChIP assays have shown that YAP binds to JOSD1's promoter region, promoting its gene transcription. These results suggest that JOSD1 is involved in both activating and being targeted by the Hippo signaling pathway in colon cancer. Consequently, a positive regulatory loop between JOSD1 and Hippo signaling has been identified, underscoring their interdependence during colon cancer progression. Thus, targeting JOSD1 may represent a promising therapeutic approach for managing colon cancer.