USP22‐mediated deubiquitination of PTEN inhibits pancreatic cancer progression by inducing p21 expression

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a dual lipid and protein phosphatase. Multiple mechanisms contributing to the regulation of PTEN levels have been identified thus far, including post‐translational modifications, epigenetic mechanisms, and transcriptional mechanisms. In the present study, we identified ubiquitin‐specific peptidase 22 (USP22) as a novel deubiquitination‐modifying enzyme of PTEN. Furthermore, by inducing deubiquitination and inhibiting the degradation of PTEN, USP22 could induce cyclin‐dependent kinase inhibitor 1A (CDKN1A, also symboled as p21) expression in pancreatic cancer. Besides, MDM2 proto‐oncogene (MDM2) inhibitor enhanced the antipancreatic cancer effects of USP22 overexpression. In addition to its regulation of MDM2‐tumor protein p53 (p53) signaling, we found that PTEN could induce p21 expression by interacting with ankyrin repeat and KH domain containing 1 (ANKHD1) and inhibiting ANKHD1 binding to the p21 promoter. Taken together, our results indicate that ANKHD1 and MDM2 might be novel therapeutic targets in pancreatic cancer.