Dual role of deubiquitinating enzyme USP19 regulates mitotic progression and tumorigenesis by stabilizing survivin

Dioscin inhibits non-small cell lung cancer cells and activates apoptosis by downregulation of Survivin

Human malignancies exhibit elevated levels of survivin, and have been linked to poor prognosis. Targeting survivin expression is a promising therapeutic strategy against cancer cells. Natural compounds have become a hot topic in research due to their non-toxic, non-invasive, and efficient treatment of multiple diseases. In this current investigation, it was discovered that Dioscin, as a natural compound, exerted profound antitumor activity against NSCLC cell lines, inhibiting NSCLC cell viability and promoting apoptosis. Further mechanistic studies showed that Dioscin promoted ubiquitination-mediated survivin degradation via strengthening the interaction between survivin and the E3 ubiquitin ligase Fbxl7. Furthermore, Dioscin exhibited a strong tumor suppressive effect in xenograft tumor models, and Dioscin treatment led to a notable decrease in tumor volume and weight. Based on our findings, Dioscin is expected to be a potential antitumor agent for non-small cell lung cancer treatment.

TRAF4 regulates ubiquitination-modulated survivin turnover and confers radioresistance

Nasopharyngeal carcinoma (NPC) is the most common cancer originating in the nasopharynx. Despite continuous improvement in treatment strategies, recurrence or persistence of cancer after radiotherapy is still inevitable, highlighting the need to identify therapeutic resistance factors and develop effective methods for NPC treatment. Herein, we found that TRAF4 is overexpressed in NPC cells and tissues. Knockdown TRAF4 significantly increased the radiosensitivity of NPC cells, possibly by inhibiting the Akt/Wee1/CDK1 axis, thereby suppressing survivin phosphorylation and promoting its degradation by FBXL7. TRAF4 is positively correlated with p-Akt and survivin in NPC tissues. High protein levels of TRAF4 were observed in acquired radioresistant NPC cells, and knockdown of TRAF4 overcomes radioresistant in vitro and the xenograft mouse model. Altogether, our study highlights the TRAF4-survivin axis as a potential therapeutic target for radiosensitization in NPC.

Survivin degradation by bergenin overcomes pemetrexed resistance

PURPOSE

Chemoresistance is a primary factor for treatment failure and tumor recurrence in non-small cell lung cancer (NSCLC) patients. The oncoprotein survivin is commonly upregulated in human malignancies and is associated with poor prognosis, but its effect on carcinogenesis and chemoresistance in NSCLC is not yet evident, and to explore an effective inhibitor targeting survivin expression is urgently needed.

METHODS

The protumor characteristics of survivin and antitumor activities of bergenin in NSCLC cells were examined by MTS, colony formation assays, immunoblot, immunohistochemistry, and in vivo xenograft development.

RESULTS

Survivin was upregulated in non-small cell lung cancer (NSCLC) tissues, while its depletion inhibited NSCLC tumorigenesis. The current study focused on bergenin, identifying its effective antitumor effect on NSCLC cells both in vivo and in vitro. The results showed that bergenin could inhibit cell proliferation and induce the intrinsic pathway of apoptosis via downregulating survivin. Mechanistically, bergenin reduced the phosphorylation of survivin via inhibiting the Akt/Wee1/CDK1 signaling pathway, thus resulting in enhanced interaction between survivin and E3 ligase Fbxl7 to promote survivin ubiquitination and degradation. Furthermore, bergenin promoted chemoresistance in NSCLC cells re-sensitized to pemetrexed treatment.

CONCLUSIONS

Survivin overexpression is required for maintaining multiple malignant phenotypes of NSCLC cells. Bergenin exerts a potent antitumor effect on NSCLC via targeting survivin, rendering it a promising agent for the treatment of NSCLC.

A risk signature based on endoplasmic reticulum stress-associated genes predicts prognosis and immunity in pancreatic cancer

Introduction: The involvement of endoplasmic reticulum (ER) stress in cancer biology is increasingly recognized, yet its role in pancreatic cancer (PC) remains unclear. This study aims to elucidate the impact of ER stress on prognosis and biological characteristics in PC patients. Methods: A bioinformatic analysis was conducted using RNA-seq data and clinicopathological information from PC patients in the TCGA and ICGC databases. The ER stress-associated gene sets were extracted from MSigDB. ER stress-associated genes closely linked with overall survival (OS) of PC patients were identified via log-rank test and univariate Cox analysis, and further narrowed by LASSO method. A risk signature associated with ER stress was formulated using multivariate Cox regression and assessed through Kaplan-Meier curves, receiver operating characteristic (ROC) analyses, and Harrell's concordance index. External validation was performed with the ICGC cohort. The single-sample gene-set enrichment analysis (ssGSEA) algorithm appraised the immune cell infiltration landscape. Results: Worse OS in PC patients with high-risk signature score was observed. Multivariate analysis underscored our ER stress-associated signature as a valuable and independent predictor of prognosis. Importantly, these results based on TCGA were further validated in ICGC dataset. In addition, our risk signature was closely associated with homeostasis, protein secretion, and immune regulation in PC patients. In particular, PC microenvironment in the high-risk cluster exhibited a more immunosuppressive status. At last, we established a nomogram model by incorporating the risk signature and clinicopathological parameters, which behaves better in predicting prognosis of PC patients. Discussion: This comprehensive molecular analysis presents a new predictive model for the prognosis of PC patients, highlighting ER stress as a potential therapeutic target. Besides, the findings indicate that ER stress can have effect modulating PC immune responses.

The deubiquitinating enzyme USP19 facilitates hepatocellular carcinoma progression through stabilizing YAP

Hippo pathway plays a crucial role in the progression of hepatocellular carcinoma (HCC), and yes-associated protein (YAP) is one of the major factors of the Hippo pathway. However, the mechanism of abnormal YAP activation in HCC has not been well elucidated. Here, we screened a Deubiquitinating enzymes' (DUB) siRNA library targeting DUBs, and identified Ubiquitin Specific Peptidase 19 (USP19) as a specific deubiquitinating enzyme of YAP in HCC, which could stabilize YAP at K76 and K90 sites via removing the K48- and K11-linked ubiquitin chains. USP19 knockdown decreased the expression of YAP protein and its target gene (CTGF, CYR61, ANKRD1) expression. Through substantial in vivo and in vitro experiments, we prove that USP19 facilities the proliferation and migration of HCC. More importantly, we found that USP19 was upregulated in HCC tissues and associated with poor prognosis. In general, our research revealed a novel post-translational mechanism between USP19 and YAP in HCC, suggesting that USP19 may be a pivotal therapeutic target for HCC treatment.

Combined Inhibition of UBE2C and PLK1 Reduce Cell Proliferation and Arrest Cell Cycle by Affecting ACLY in Pan-Cancer

Various studies have shown that the cell-cycle-related regulatory proteins UBE2C, PLK1, and BIRC5 promote cell proliferation and migration in different types of cancer. However, there is a lack of in-depth and systematic research on the mechanism of these three as therapeutic targets. In this study, we found a positive correlation between the expression of UBE2C and PLK1/BIRC5 in the Cancer Genome Atlas (TCGA) database, revealing a potential combination therapy candidate for pan-cancer. Quantitative real-time PCR (qRT-PCR), Western blotting (WB), cell phenotype detection, and RNA-seq techniques were used to evidence the effectiveness of the combination candidate. We found that combined interference of UBE2C with PLK1 and UBE2C with BIRC5 affected metabolic pathways by significantly downregulating the mRNA expression of IDH1 and ACLY, which was related to the synthesis of acetyl-CoA. By combining the PLK1 inhibitor volasertib and the ACLY inhibitor bempedoic acid, it showed a higher synergistic inhibition of cell viability and higher synergy scores in seven cell lines, compared with those of other combination treatments. Our study reveals the potential mechanisms through which cell-cycle-related genes regulate metabolism and proposes a potential combined targeted therapy for patients with higher PLK1 and ACLY expression in pan-cancer.

Gastrodin destabilizes survivin and overcomes pemetrexed resistance

Survivin is a bifunctional protein that plays crucial roles in tumorigenesis. In the present study, we discovered that the natural product gastrodin suppressed the cell viability and colony formation of non-small cell lung cancer (NSCLC) cell lines A549, HCC827, and H460 in a dose-dependent manner. In addition, gastrodin enhanced the protein levels of cleaved-caspase 3 by activating the endogenous mitochondrial apoptosis pathway. Gastrodin inhibits protein kinase B (Akt)/WEE1/cyclin-dependent kinase 1 (CDK1) signaling to downregulate survivin Thr34 phosphorylation. Survivin Thr34 dephosphorylation caused by gastrodin interfered with the binding of ubiquitin-specific protease 19 (USP19), which eventually destabilized survivin. We revealed that the growth of NSCLC xenograft tumors was markedly suppressed by gastrodin in vivo. Furthermore, gastrodin overcomes pemetrexed resistance in vivo or in vitro. Our results suggest that gastrodin is a potential antitumor agent by reducing survivin in NSCLC.

Inhibition of USP2 Enhances TRAIL-Mediated Cancer Cell Death through Downregulation of Survivin

Ubiquitin-specific protease 2 (USP2) is a deubiquitinase belonging to the USPs subfamily. USP2 has been known to display various biological effects including tumorigenesis and inflammation. Therefore, we aimed to examine the sensitization effect of USP2 in TRAIL-mediated apoptosis. The pharmacological inhibitor (ML364) and siRNA targeting USP2 enhanced TNF-related apoptosis-inducing ligand (TRAIL)-induced cancer cell death, but not normal cells. Mechanistically, USP2 interacted with survivin, and ML364 degraded survivin protein expression by increasing the ubiquitination of survivin. Overexpression of survivin or USP2 significantly prevented apoptosis through cotreatment with ML364 and TRAIL, whereas a knockdown of USP2 increased sensitivity to TRAIL. Taken together, our data suggested that ML364 ubiquitylates and degrades survivin, thereby increasing the reactivity to TRAIL-mediated apoptosis in cancer cells.

USP19 Negatively Regulates p53 and Promotes Cervical Cancer Progression

p53 is a tumor suppressor gene activated in response to cellular stressors that inhibits cell cycle progression and induces pro-apoptotic signaling. The protein level of p53 is well balanced by the action of several E3 ligases and deubiquitinating enzymes (DUBs). Several DUBs have been reported to negatively regulate and promote p53 degradation in tumors. In this study, we identified USP19 as a negative regulator of p53 protein level. We demonstrate a direct interaction between USP19 and p53 by pull down assay. The overexpression of USP19 promoted ubiquitination of p53 and reduced its protein half-life. We also demonstrate that CRISPR/Cas9-mediated knockout of USP19 in cervical cancer cells elevates p53 protein levels, resulting in reduced colony formation, cell migration, and cell invasion. Overall, our results indicate that USP19 negatively regulates p53 protein levels in cervical cancer progression.

Dioscin inhibiting EGFR-mediated Survivin expression promotes apoptosis in oral squamous cell carcinoma cells

Overexpression of survivin plays a crucial role in tumorigenesis and correlates with poor prognosis in human malignancies, including oral squamous cell carcinoma (OSCC). Thus, survivin has been proposed as an attractive target for new antitumor interventions. In the present study, we found that a natural compound, Dioscin, inhibited OSCC cells by reducing the survivin protein level and activating apoptotic signaling. Dioscin inhibits survivin expression by interrupting EGFR binding to the AT-rich sequences (ATRSs) at the survivin promoter, eventually promoting survivin-mediated cell apoptosis. The in vivo study showed that Dioscin suppressed the tumor development of SCC25 cells. Furthermore, the immunohistochemistry (IHC) results revealed that treated with Dioscin reduced the protein levels of EGFR and survivin in SCC25 xenograft tumors. Overall, our findings indicate that targeting the EGFR-survivin axis might be a promising OSCC treatment strategy.

CRISPR/Cas9-based genome-wide screening of the deubiquitinase subfamily identifies USP3 as a protein stabilizer of REST blocking neuronal differentiation and promotes neuroblastoma tumorigenesis

BACKGROUND

The repressor element-1 silencing transcription factor (REST), a master transcriptional repressor, is essential for maintenance, self-renewal, and differentiation in neuroblastoma. An elevated expression of REST is associated with impaired neuronal differentiation, which results in aggressive neuroblastoma formation. E3 ligases are known to regulate REST protein abundance through the 26 S proteasomal degradation pathway in neuroblastoma. However, deubiquitinating enzymes (DUBs), which counteract the function of E3 ligase-mediated REST protein degradation and their impact on neuroblastoma tumorigenesis have remained unexplored.

METHODS

We employed a CRISPR/Cas9 system to perform a genome-wide knockout of ubiquitin-specific proteases (USPs) and used western blot analysis to screen for DUBs that regulate REST protein abundance. The interaction between USP3 and REST was confirmed by immunoprecipitation and Duolink in situ proximity assays. The deubiquitinating effect of USP3 on REST protein degradation, half-life, and neuronal differentiation was validated by immunoprecipitation, in vitro deubiquitination, protein-turnover, and immunostaining assays. The correlation between USP3 and REST expression was assessed using patient neuroblastoma datasets. The USP3 gene knockout in neuroblastoma cells was performed using CRISPR/Cas9, and the clinical relevance of USP3 regulating REST-mediated neuroblastoma tumorigenesis was confirmed by in vitro and in vivo oncogenic experiments.

RESULTS

We identified a deubiquitinase USP3 that interacts with, stabilizes, and increases the half-life of REST protein by counteracting its ubiquitination in neuroblastoma. An in silico analysis showed a correlation between USP3 and REST in multiple neuroblastoma cell lines and identified USP3 as a prognostic marker for overall survival in neuroblastoma patients. Silencing of USP3 led to a decreased self-renewal capacity and promoted retinoic acid-induced differentiation in neuroblastoma. A loss of USP3 led to attenuation of REST-mediated neuroblastoma tumorigenesis in a mouse xenograft model.

CONCLUSION

The findings of this study indicate that USP3 is a critical factor that blocks neuronal differentiation, which can lead to neuroblastoma. We envision that targeting USP3 in neuroblastoma tumors might provide an effective therapeutic differentiation strategy for improved survival rates of neuroblastoma patients.