RNF4 promotes tumorigenesis, therapy resistance of cholangiocarcinoma and affects cell cycle by regulating the ubiquitination degradation of p27kip1 in the nucleus

Nuclear pore complex protein RANBP2 and related SUMOylation in solid malignancies

The growing interest in post-translational protein modification, particularly in SUMOylation, is driven by its crucial role in cell cycle regulation. SUMOylation affects various cell cycle regulators, including oncogenes, suggesting its relevance in cancer. SUMO E3 ligases are pivotal in this process, exhibiting diverse functionalities through structural domains and subcellular localizations. A less-explored SUMO E3 ligase, RANBP2, a component of the vertebrate nuclear pore complex, emerges as a central player in cellular cycle processes, as well as in tumorigenesis. The current studies illuminate the importance of RANBP2 and underscore the need for more extensive studies to validate its clinical applicability in neoplastic interventions. Our review elucidates the significance of RANBP2 across various types of malignancies. Additionally, it delves into exploring RANBP2 as a prospective therapeutic target for cancer treatment, offering insights into the avenues that scholars should pursue in their subsequent research endeavors. Thus, further investigation into RANBP2's role in solid tumorigenesis is eagerly awaited.

RNF4 mediated degradation of PDHA1 promotes colorectal cancer metabolism and metastasis

This study investigates the role of RNF4-mediated ubiquitination and degradation of PDHA1 in colorectal cancer (CRC) metabolism and metastasis. Integrating (The Cancer Genome Atlas) TCGA and Clinical Proteomic Tumor Analysis Consortium (CPTAC) databases, proteomic, clinical, and metabolomic analyses were performed, revealing PDHA1 as a prognostic marker in CRC. Immunohistochemical staining confirmed lower PDHA1 expression in metastatic CRC tissues. In vitro experiments demonstrated that PDHA1 overexpression inhibited CRC cell proliferation, migration, and invasion. RNF4 was identified as a key mediator in the ubiquitination degradation of PDHA1, influencing glycolytic pathways in CRC cells. Metabolomic analysis of serum samples from metastatic CRC patients further supported these findings. In vivo experiments, including xenograft and metastasis models, validated that RNF4 knockdown stabilized PDHA1, inhibiting tumor formation and metastasis. This study highlights the critical role of RNF4-mediated PDHA1 ubiquitination in promoting glycolytic metabolism, proliferation, and metastasis in CRC.

RNF4 prevents genomic instability caused by chronic DNA under-replication

Eukaryotic genome stability is maintained by a complex and diverse set of molecular processes. One class of enzymes that promotes proper DNA repair, replication and cell cycle progression comprises small ubiquitin-like modifier (SUMO)-targeted E3 ligases, or STUbLs. Previously, we reported a role for the budding yeast STUbL synthetically lethal with sgs1 (Slx) 5/8 in preventing G2/M-phase arrest in a minichromosome maintenance protein 10 (Mcm10)-deficient model of replication stress. Here, we extend these studies to human cells, examining the requirement for the human STUbL RING finger protein 4 (RNF4) in MCM10 mutant cancer cells. We find that MCM10 and RNF4 independently promote origin firing but regulate DNA synthesis epistatically and, unlike in yeast, the negative genetic interaction between RNF4 and MCM10 causes cells to accumulate in G1-phase. When MCM10 is deficient, RNF4 prevents excessive DNA under-replication at hard-to-replicate regions that results in large DNA copy number alterations and severely reduced viability. Overall, our findings highlight that STUbLs participate in species-specific mechanisms to maintain genome stability, and that human RNF4 is required for origin activation in the presence of chronic replication stress.