USP7- and PRMT5-dependent G3BP2 stabilization drives de novo lipogenesis and tumorigenesis of HNSC

Stress granules in cancer: Adaptive dynamics and therapeutic implications

Stress granules (SGs), membrane-less cellular organelles formed via liquid-liquid phase separation, are central to how cells adapt to various stress conditions, including endoplasmic reticulum stress, nutrient scarcity, and hypoxia. Recent studies have underscored a significant link between SGs and the process of tumorigenesis, highlighting that proteins, associated components, and signaling pathways that facilitate SG formation are often upregulated in cancer. SGs play a key role in enhancing tumor cell proliferation, invasion, and migration, while also inhibiting apoptosis, facilitating immune evasion, and driving metabolic reprogramming through multiple mechanisms. Furthermore, SGs have been identified as crucial elements in the development of resistance against chemotherapy, immunotherapy, and radiotherapy across a variety of cancer types. This review delves into the complex role of SGs in cancer development and resistance, bringing together the latest progress in the field and exploring new avenues for therapeutic intervention.

PiR-hsa-23533 promotes malignancy in head and neck squamous cell carcinoma via USP7

BACKGROUND

With regard to head and neck squamous cell carcinoma (HNSCC), its occurrence and advancement are controlled by genetic and epigenetic anomalies. PIWI-interacting RNAs (piRNAs) are recognized with significance in tumor, but the precise molecular mechanisms of piRNAs in HNSCC largely remain undisclosed.

METHODS

Differentially expressed piRNAs were identified by RNA sequencing. The expression of piR-hsa-23533 was evaluated using quantitative real-time PCR and RNA in situ hybridization. The impacts of piR-hsa-23533 on the proliferation and apoptosis of HNSCC cells were investigated by a series of in vitro and in vivo assays.

RESULTS

piR-hsa-23533 exhibits upregulation within HNSCC cells and tissues. Besides, piR-hsa-23533 overexpression promotes proliferation while inhibiting apoptosis in vitro and in vivo, while piR-hsa-23533 silencing has an opposite function. From the mechanistic perspective, piR-hsa-23533 can bind to Ubiquitin-specific protease 7 (USP7), as shown through RNA pull-down and RNA immunoprecipitation assays, promoting USP7 mRNA and protein expression.

CONCLUSIONS

These findings highlight the functional importance of piR-hsa-23533 in HNSCC and may assist in the development of anti-HNSCC therapeutic target.

ZNF692 promotes the migration and response to immunotherapy of clear cell renal cell carcinoma cells by targeting metabolic pathway

Clear cell renal cell carcinoma (ccRCC), with high mortality and poor prognosis, is the most common type of renal malignancy. It is necessary to identify new biomarkers that can serve as indicators for the detection of ccRCC at its early stages. In this study, we analyzed the role of classical zinc finger protein 692 (ZNF692) in ccRCC using datasets from The Cancer Genome Atlas (TCGA) and Single Cell Portal and immunohistochemical (IHC) staining of a tissue-microarray, and analyzed the function of ZNF692 in ccRCC cells. The analyses indicated that ZNF692 was upregulated in ccRCC samples compared with normal or paracancerous control samples (P < 0.001) and that the expression of this gene was linked to poor overall survival (HR = 2.1, P < 0.0001). The knockdown of ZNF692 inhibited the proliferation and migration of ccRCC cells by target GTPase-activating protein (SH3 domain)-binding protein 2 (G3BP2), and transmembrane 9 superfamily member 2 (TM9SF2)). T, B, proximal, and collecting tubule cells are the dominant cell types in normal kidney tissue where ZNF692 is expressed. In addition, immune checkpoint blockade (ICB) therapy dramatically changed the expression patterns of ZNF692. Collectively, these data indicate that ZNF692 may serve as prognosis, and as a potential indicator of the response to ICB therapy, a possibility needs to be verified by a case‒control study.

Stabilization of KPNB1 by deubiquitinase USP7 promotes glioblastoma progression through the YBX1-NLGN3 axis

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor of the central nervous system. It is an aggressive tumor characterized by rapid proliferation, diffuse tumor morphology, and poor prognosis. Unfortunately, current treatments, such as surgery, radiotherapy, and chemotherapy, are unable to achieve good outcomes. Therefore, there is an urgent need to explore new treatment targets. A detailed mechanistic exploration of the role of the nuclear pore transporter KPNB1 in GBM is lacking. This study demonstrated that KPNB1 regulated GBM progression through a transcription factor YBX1 to promote the expression of post-protrusion membrane protein NLGN3. This regulation was mediated by the deubiquitinating enzyme USP7.

METHODS

A tissue microarray was used to measure the expression of KPNB1 and USP7 in glioma tissues. The effects of KPNB1 knockdown on the tumorigenic properties of glioma cells were characterized by colony formation assays, Transwell migration assay, EdU proliferation assays, CCK-8 viability assays, and apoptosis analysis using flow cytometry. Transcriptome sequencing identified NLGN3 as a downstream molecule that is regulated by KPNB1. Mass spectrometry and immunoprecipitation were performed to analyze the potential interaction between KPNB1 and YBX1. Moreover, the nuclear translocation of YBX1 was determined with nuclear-cytoplasmic fractionation and immunofluorescence staining, and chromatin immunoprecipitation assays were conducted to study DNA binding with YBX1. Ubiquitination assays were performed to determine the effects of USP7 on KPNB1 stability. The intracranial orthotopic tumor model was used to detect the efficacy in vivo.

RESULTS

In this study, we found that the nuclear receptor KPNB1 was highly expressed in GBM and could mediate the nuclear translocation of macromolecules to promote GBM progression. Knockdown of KPNB1 inhibited the progression of GBM, both in vitro and in vivo. In addition, we found that KPNB1 could regulate the downstream expression of Neuroligin-3 (NLGN3) by mediating the nuclear import of transcription factor YBX1, which could bind to the NLGN3 promoter. NLGN3 was necessary and sufficient to promote glioma cell growth. Furthermore, we found that deubiquitinase USP7 played a critical role in stabilizing KPNB1 through deubiquitination. Knockdown of USP7 expression or inhibition of its activity could effectively impair GBM progression. In vivo experiments also demonstrated the promoting effects of USP7, KPNB1, and NLGN3 on GBM progression. Overall, our results suggested that KPNB1 stability was enhanced by USP7-mediated deubiquitination, and the overexpression of KPNB1 could promote GBM progression via the nuclear translocation of YBX1 and the subsequent increase in NLGN3 expression.

CONCLUSION

This study identified a novel and targetable USP7/KPNB1/YBX1/NLGN3 signaling axis in GBM cells.

Decoding protein methylation function with thermal stability analysis

Protein methylation is an important modification beyond epigenetics. However, systems analyses of protein methylation lag behind compared to other modifications. Recently, thermal stability analyses have been developed which provide a proxy of a protein functional status. Here, we show that molecular and functional events closely linked to protein methylation can be revealed by the analysis of thermal stability. Using mouse embryonic stem cells as a model, we show that Prmt5 regulates mRNA binding proteins that are enriched in intrinsically disordered regions and involved in liquid-liquid phase separation mechanisms, including the formation of stress granules. Moreover, we reveal a non-canonical function of Ezh2 in mitotic chromosomes and the perichromosomal layer, and identify Mki67 as a putative Ezh2 substrate. Our approach provides an opportunity to systematically explore protein methylation function and represents a rich resource for understanding its role in pluripotency.