DNAAF5 promotes hepatocellular carcinoma malignant progression by recruiting USP39 to improve PFKL protein stability

USP39 promote post-translational modifiers to stimulate the progress of cancer

Deubiquitinating enzymes (DUBs) are a class of crucial peptidyl hydrolases within the ubiquitin system, playing a significant role in reversing and strictly regulating ubiquitination, which is essential for various biological processes such as protein stability and cellular signal transduction. Ubiquitin-specific protease 39 (USP39) is an important member of the DUBs family. Recent studies have revealed that USP39 is involved in the regulation of multiple cellular activities including cell proliferation, migration, invasion, apoptosis, and DNA damage repair. USP39 also plays a significant role in the development and progression of various cancers. It is believed that USP39 is a unique enzyme that controls the ubiquitin process and is closely associated with the occurrence and progression of many cancers, including hepatocellular, lung, gastric, breast, and ovarian cancer. This review summarizes the structural and functional aspects of USP39 and its research advancements in tumors, investigates the key molecular mechanisms related to USP39, and provides references for tumor diagnosis and treatment.

Exploring the cancerous nexus: the pivotal and diverse roles of USP39 in cancer development

The ubiquitin-proteasome system enables post-transcriptional protein modification and is a major pathway for the degradation of most of them in eukaryotic cells. Among these, the ubiquitin-specific protease (USP) family is the most extensively studied. As an important member of the USP family, ubiquitin-specific protease 39 (USP39) plays an essential role in RNA splicing and protein regulation. This review comprehensively summarizes the structural characteristics and molecular functions of USP39, emphasizing its pivotal role in the regulation of cellular processes. Dysregulation of USP39 is closely associated with the progression of various cancers through mechanisms such as immune evasion, modulation of oncogenic signaling pathways, and altered RNA splicing. These processes impact key aspects of cancer biology, including proliferation, metastasis, and therapy resistance, underscoring the broad implications of USP39 in tumor progression. Recent studies position USP39 as a promising target for cancer treatment. Future research should explore its upstream regulatory networks, develop small-molecule inhibitors, and evaluate its potential for precision oncology. This review integrates the latest insight into USP39, providing a foundation for its clinical application in cancer therapy.

Toosendanin promotes prostate cancer cell apoptosis, ferroptosis and M1 polarization via USP39-mediated PLK1 deubiquitination

Toosendanin (TSN) can inhibit the malignant process of many cancers, and has the potential to be developed as an anti-tumor drug. However, the role and mechanism of TSN in prostate cancer (PCa) progression remain unclear. PCa cells (DU145 and LNCaP) were treated with TSN. Cell viability was detected by cell counting kit 8 assay. Cell proliferation, apoptosis and metastasis were assessed by colony formation assay, flow cytometry and transwell assay. Cell ferroptosis was evaluated by examining Fe2+, MDA and lipid-ROS levels. M1 polarization markers were analyzed by flow cytometry. Immunohistochemical staining, quantitative real-time PCR and western blot were used to detect ubiquitin-specific protease 39 (USP39) and polo-like kinase 1 (PLK1) expression. Cycloheximide treatment, Co-IP assay and ubiquitination assay were performed to confirm the regulation of USP39 on PLK1. In vivo experiments were employed to determine the effect of TSN and USP39 on PCa tumor growth. TSN treatment suppressed PCa cell proliferation, cell cycle, migration, and invasion, while enhanced apoptosis, ferroptosis, and M1 polarization. USP39 was upregulated in PCa tissues and cells, and its protein expression was reduced by TSN. USP39 overexpression reversed the regulation of TSN on PCa cell functions. PLK1 had elevated expression in PCa, and USP39 stabilized its protein expression by deubiquitination. USP39 knockdown inhibited PCa cell behaviors, and its regulation was abolished by PLK1 overexpression. Meanwhile, TSN reduced PCa tumor growth by regulating USP39/PLK1. TSN played anti-tumor role in PCa, which promoted PCa cell apoptosis, ferroptosis, and M1 polarization by inhibiting USP39/PLK1 axis.

RBM12 drives PD-L1-mediated immune evasion in hepatocellular carcinoma by increasing JAK1 mRNA translation

Immunosuppression characterizes the tumour microenvironment in HCC, and recent studies have implicated RNA-binding proteins (RBPs) in the development of HCC. Here, we conducted a screen and identified RBM12 as a key protein that increased the expression of PD-L1, thereby driving immune evasion in HCC. Furthermore, RBM12 was found to be significantly upregulated in HCC tissues and was associated with a poor prognosis for HCC patients. Through various molecular assays and high-throughput screening, we determined that RBM12 could directly bind to the JAK1 mRNA via its 4th-RRM (RNA recognition motif) domain and recruit EIF4A2 through its 2nd-RRM domain, enhancing the distribution of ribosomes on JAK1 mRNA, which promotes the translation of JAK1 and the subsequent upregulation of its expression. As a result, the activated JAK1/STAT1 pathway transcriptionally upregulates PD-L1 expression, facilitating immune evasion in HCC. In summary, our findings provide insights into the significant contribution of RBM12 to immune evasion in HCC, highlighting its potential as a therapeutic target in the future. This graphical abstract shows that elevated expression of RBM12 in HCC can augment PD-L1-mediated tumour immune evasion by increasing the efficiency of JAK1 mRNA translation.

EGR1 suppresses HCC growth and aerobic glycolysis by transcriptionally downregulating PFKL

BACKGROUND

Hepatocellular Carcinoma (HCC) is a matter of great global public health importance; however, its current therapeutic effectiveness is deemed inadequate, and the range of therapeutic targets is limited. The aim of this study was to identify early growth response 1 (EGR1) as a transcription factor target in HCC and to explore its role and assess the potential of gene therapy utilizing EGR1 for the management of HCC.

METHODS

In this study, both in vitro and in vivo assays were employed to examine the impact of EGR1 on the growth of HCC. The mouse HCC model and human organoid assay were utilized to assess the potential of EGR1 as a gene therapy for HCC. Additionally, the molecular mechanism underlying the regulation of gene expression and the suppression of HCC growth by EGR1 was investigated.

RESULTS

The results of our investigation revealed a notable decrease in the expression of EGR1 in HCC. The decrease in EGR1 expression promoted the multiplication of HCC cells and the growth of xenografted tumors. On the other hand, the excessive expression of EGR1 hindered the proliferation of HCC cells and repressed the development of xenografted tumors. Furthermore, the efficacy of EGR1 gene therapy was validated using in vivo mouse HCC models and in vitro human hepatoma organoid models, thereby providing additional substantiation for the anti-cancer role of EGR1 in HCC. The mechanistic analysis demonstrated that EGR1 interacted with the promoter region of phosphofructokinase-1, liver type (PFKL), leading to the repression of PFKL gene expression and consequent inhibition of PFKL-mediated aerobic glycolysis. Moreover, the sensitivity of HCC cells and xenografted tumors to sorafenib was found to be increased by EGR1.

CONCLUSION

Our findings suggest that EGR1 possesses therapeutic potential as a tumor suppressor gene in HCC, and that EGR1 gene therapy may offer benefits for HCC patients.