Restraining CDK1-cyclin B activation: PP2A on the cUSP(7)

TRIM-endous functional network of tripartite motif 29 (TRIM29) in cancer progression and beyond

While most Tripartite motif (TRIM) family proteins are E3 ubiquitin ligases, some members have functions beyond the regulation of ubiquitination, impacting normal physiological processes and disease progression. TRIM29, an important member of the TRIM family, exerts a predominant influence on cancer growth, epithelial-to-mesenchymal transition, stemness and metastatic progression by directly potentiating multiple canonical oncogenic pathways. The cancer-promoting effect of TRIM29 is also evident in metabolic interventions and interference with the efficacy of cancer therapeutics. As expected for any key node in cancer, the expression of TRIM29 is tightly regulated by non-coding RNAs, epigenetic modulation, and post-translational regulation. A systematic discussion of how TRIM29 is regulated in cancer, its influences on cancer progression, and its impact on cancer therapeutics is presented in this review. We also explore the context-dependent alterations between TRIM29 function from oncogenic to tumor suppression. As TRIM29 is involved in multiple aspects of cancer progression, a better understanding of its biological impact in cancer may help improve prognosis and develop novel therapeutic combinations, leading to improved personalized cancer care.

USP7 as an emerging therapeutic target: A key regulator of protein homeostasis

Maintaining protein balance within a cell is essential for proper cellular function, and disruptions in the ubiquitin-proteasome pathway, which is responsible for degrading and recycling unnecessary or damaged proteins, can lead to various diseases. Deubiquitinating enzymes play a vital role in regulating protein homeostasis by removing ubiquitin chains from substrate proteins, thereby controlling important cellular processes, such as apoptosis and DNA repair. Among these enzymes, ubiquitin-specific protease 7 (USP7) is of particular interest. USP7 is a cysteine protease consisting of a TRAF region, catalytic region, and C-terminal ubiquitin-like (UBL) region, and it interacts with tumor suppressors, transcription factors, and other key proteins involved in cell cycle regulation and epigenetic control. Moreover, USP7 has been implicated in the pathogenesis and progression of various diseases, including cancer, inflammation, neurodegenerative conditions, and viral infections. Overall, characterizing the functions of USP7 is crucial for understanding the pathophysiology of diverse diseases and devising innovative therapeutic strategies. This article reviews the structure and function of USP7 and its complexes, its association with diseases, and its known inhibitors and thus represents a valuable resource for advancing USP7 inhibitor development and promoting potential future treatment options for a wide range of diseases.

TRIM29 regulates the SETBP1/SET/PP2A axis via transcription factor VEZF1 to promote progression of ovarian cancer

Ovarian cancer (OC) is a common gynecological malignant tumor that seriously endangers the health of women worldwide. Tripartite motif containing 29 (TRIM29) is a TRIM family member that is frequently overexpressed in OC. However, the specific role of TRIM29 in OC remains obscure. To investigate the underlying molecular mechanism, a global proteomics analysis identified SET binding protein 1 (SETBP1) as a crucial target of TRIM29. Subsequently, the SETBP1/SET/Protein phosphatase 2 (PP2A) axis was confirmed to be required for the recovery of cancer stem cell (CSC)-like phenotype suppressed by TRIM29 knockdown. Mechanistically, TRIM29 facilitated SETBP1 transcriptional activation via the VEZF1 transcription factor. More importantly, TRIM29 promoted VEZF1 mRNA translation by recruiting RNA binding protein BICC1 to its 3'UTR. The clinical significance was established by the association of TRIM29 and SETBP1 expression with clinicopathological features in OC samples. The SETBP1/SET/PP2A axis driven by TRIM29 via transcription factor VEZF1 is at least one of the primary mechanisms underlying TRIM29 maintenance of the CSC-like characteristics in OC.

Restraining CDK1-cyclin B activation: PP2A on the cUSP(7)

USP7 inhibitors are gaining momentum as a therapeutic strategy to stabilize p53 through their ability to induce MDM2 degradation. However, these inhibitors come with an unexpected p53-independent toxicity, via an unknown mechanism. In this issue of The EMBO Journal, Galarreta et al report how inhibition of USP7 leads to re-distribution of PP2A from cytoplasm to nucleus and an increase of deleterious CDK1-dependent phosphorylation throughout the cell cycle, revealing a new regulatory mechanism for the progression of S-phase cells toward mitosis to maintain genomic integrity.