WSB1 regulates c-Myc expression through β-catenin signaling and forms a feedforward circuit

WSB1/2 target chromatin-bound lysine-methylated RelA for proteasomal degradation and NF-κB termination

Proteasome-mediated degradation of chromatin-bound NF-κB is critical in terminating the transcription of pro-inflammatory genes and can be triggered by Set9-mediated lysine methylation of the RelA subunit. However, the E3 ligase targeting methylated RelA remains unknown. Here, we find that two structurally similar substrate-recognizing components of Cullin-RING E3 ligases, WSB1 and WSB2, can recognize chromatin-bound methylated RelA for polyubiquitination and proteasomal degradation. We showed that WSB1/2 negatively regulated a subset of NF-κB target genes via associating with chromatin where they targeted methylated RelA for ubiquitination, facilitating the termination of NF-κB-dependent transcription. WSB1/2 specifically interacted with methylated lysines (K) 314 and 315 of RelA via their N-terminal WD-40 repeat (WDR) domains, thereby promoting ubiquitination of RelA. Computational modeling further revealed that a conserved aspartic acid (D) at position 158 within the WDR domain of WSB2 coordinates K314/K315 of RelA, with a higher affinity when either of the lysines is methylated. Mutation of D158 abolished WSB2's ability to bind to and promote ubiquitination of methylated RelA. Together, our study identifies a novel function and the underlying mechanism for WSB1/2 in degrading chromatin-bound methylated RelA and preventing sustained NF-κB activation, providing potential new targets for therapeutic intervention of NF-κB-mediated inflammatory diseases.

WSB1, as an E3 ligase, restrains myocardial ischemia-reperfusion injury by activating β-catenin signaling via promoting GSK3β ubiquitination

BACKGROUND

Reperfusion is the most effective strategy for myocardial infarct, but induces additional injury. WD repeat and SOCS box containing protein 1 (WSB1) plays a protective role in ischemic cells. This study aims to investigate the effects of WSB1 on myocardial ischemia-reperfusion (IR) injury.

METHODS

The myocardial IR was induced by left anterior descending (LAD) ligation for 45 min and subsequent reperfusion. The overexpression of WSB1 was mediated by tail vein injection of AAV9 loaded with WSB1 encoding sequence two weeks before IR surgery. H9c2 myocardial cells underwent oxygen-sugar deprivation/reperfusion (OGD/R) to mimic IR, and transfected with WSB1 overexpression or silencing plasmid to alter the expression of WSB1.

RESULTS

WSB1 was found highly expressed in penumbra of myocardial IR rats, and the WSB1 overexpression relieved IR-induced cardio dysfunction, myocardial infarct and pathological damage, and cardiomyocyte death in penumbra. The ectopic expression of WSB1 in H9c2 myocardial cells mitigated OGD/R-caused apoptosis, and silencing of WSB1 exacerbated the apoptosis. In addition, WSB1 activated β-catenin signaling, which was deactivated under the ischemic condition. The co-immunoprecipitation results revealed that WSB1 mediated ubiquitination and degradation of glycogen synthase kinase 3 beta (GSK3β) as an E3 ligase in myocardial cells. The effects of WSB1 on myocardial cells under ischemic conditions were abolished by an inhibitor of β-catenin signaling.

CONCLUSION

WSB1 activated β-catenin pathway by promoting the ubiquitination of GSK3β, and restrained IR-induced myocardial injury. These findings might provide novel insights for clinical treatment of myocardial ischemic patients.

The role of abnormal ubiquitination in hepatocellular carcinoma pathology

Primary liver cancer is known for its high incidence and fatality rate. Over the years, therapeutic strategies for primary liver cancer have advanced significantly. Nonetheless, a substantial number of patients have not benefited from these methods, underscoring the pressing need for new and effective treatments for primary liver cancer. Ubiquitination is a critical post-translational modification that enables proteins to fulfill their normal biological functions and maintain their expression stability within cells. Importantly, increasing evidence suggests that the progression of liver cancer cells is often accompanied by disruptions in protein ubiquitination and deubiquitination processes. In this comprehensive review, we have compiled pertinent research about dysregulated ubiquitination in hepatocellular carcinoma (HCC) to broaden our understanding in this field. We elucidate the connections between the ubiquitination proteasome system, deubiquitination, and HCC. Furthermore, we shed light on the role of ubiquitination in cells situated within the tumor microenvironment of HCC including its involvement in mediating the activation of oncogenic pathways, reprogramming metabolic processes, and perturbing normal cellular functions. In conclusion, targeting the dysregulation of ubiquitination in HCC holds promise as a prospective and complementary therapeutic approach to existing treatments.

Sevoflurane suppresses colorectal cancer malignancy by modulating β-catenin ubiquitination degradation via circSKA3

BACKGROUND

Sevoflurane (SEV), a commonly used inhalational anesthetic, reportedly inhibits colorectal cancer (CRC) malignancy, but whether SEV can inhibit the malignancy of CRC by regulating circular RNAs (circRNAs) remains unclear. Therefore, we aimed to identify specific circRNAs that may be affected by SEV and to investigate their functional roles in CRC.

METHODS

RT-qPCR was employed to detect the expression of circRNAs and mRNAs in CRC cells and tissues. Fluorescence in situ hybridization (FISH) was used to determine the location of circSKA3. Protein expression was assessed by western blot analysis. Function-based in vitro and in vivo experiments, including CCK-8, colony formation, transwell, and apoptosis assays and mouse xenograft tumor models, were conducted using circSKA3-knockdown and circSKA3-overexpression cell lines. RNA immunoprecipitation, RNA pull-down and mass spectrometry analyses were performed to explore the related mechanism.

RESULTS

Our findings revealed that SEV could inhibit CRC cell activity, proliferation and migration and promote apoptosis in CRC cells. We found that circSKA3 was upregulated in CRC and associated with poorer survival and that its expression could be reduced by SEV. The overexpression of circSKA3 reversed the effects of SEV on inhibiting cell activity, proliferation and migration and promoting apoptosis. The mechanistic analysis revealed that circSKA3 could bind to the ARM structural domain of β-catenin and thereby disrupt its interaction with the CK1/GSK3β/β-TrCP1 destruction complex, resulting in the ubiquitinated degradation of β-catenin and the activation of Wnt/β-catenin signaling. In addition, SEV downregulated circSKA3 in vivo to inhibit tumor growth.

CONCLUSIONS

All the results showed that SEV could inhibit CRC progression via circSKA3 by increasing β-catenin ubiquitination degradation.

circWSB1 promotes tumor progression in ccRCC via circWSB1/miR-182-5p/WSB1 axis

Clear cell renal cell carcinoma (ccRCC) is one of the most prevalent urological carcinomas with a low overall 5-year survival rate, and its prognosis remains dismal. circular RNAs (circRNAs) has been discovered to be important regulators in ccRCC. However, the specific regulatory mechanisms of circRNAs and their impact on phenotypes require further in-depth research. circRNA microarray sequencing analysis was used in this study to explore the expression pattern of circRNAs in ccRCC. circWSB1 was discovered, and we evaluated its derivation, potential diagnostic efficacy, and prognostic significance in ccRCC tissues. We discovered that circWSB1 is highly expressed in ccRCC. We identified that circWSB1 interacts with miR-182-5p and upregulates the expression of its host gene, WSB1. Through models in vivo and in vitro models, we found that circWSB1 increases WSB1 expression via the circWSB1/miR-182-5p/WSB1 axis, which promotes ccRCC cell proliferation and migration. The high expression of circWSB1 and WSB1 is correlated with poorer clinical prognosis and pathological grading. circWSB1 diminishes the inhibitory impact of miR-182-5p on WSB1 and increases WSB1 expression, thereafter promoting ccRCC development. Our findings provide a promising predictive biomarker and therapeutic target for ccRCC.

MYC in liver cancer: mechanisms and targeted therapy opportunities

MYC, a major oncogenic transcription factor, regulates target genes involved in various pathways such as cell proliferation, metabolism and immune evasion, playing a critical role in the tumor initiation and development in multiple types of cancer. In liver cancer, MYC and its signaling pathways undergo significant changes, exerting a profound impact on liver cancer progression, including tumor proliferation, metastasis, dedifferentiation, metabolism, immune microenvironment, and resistance to comprehensive therapies. This makes MYC an appealing target, despite it being previously considered an undruggable protein. In this review, we discuss the role and mechanisms of MYC in liver physiology, chronic liver diseases, hepatocarcinogenesis, and liver cancer progression, providing a theoretical basis for targeting MYC as an ideal therapeutic target for liver cancer. We also summarize and prospect the strategies for targeting MYC, including direct and indirect approaches to abolish the oncogenic function of MYC in liver cancer.

WSB1 Involvement in Prostate Cancer Progression

Prostate cancer (PC) is polygenic disease involving many genes, and more importantly a host of gene-gene interactions, including transcriptional factors. The WSB1 gene is a transcriptional target of numerous oncoproteins, and its dysregulation can contribute to tumor progression by abnormal activation of targeted oncogenes. Using data from the Cancer Genome Atlas, we tested the possible involvement of WSB1 in PC progression. A multi-dimensional scaling (MDS) model was applied to clarify the association of WSB1 expression with other key genes, such as c-myc, ERG, Enhancer of Zeste 1 and 2 (EHZ1 and EZH2), WNT10a, and WNT 10b. An increased WSB1 expression was associated with higher PC grades and with a worse prognosis. It was also positively related to EZH1, EZH2, WNT10a, and WNT10b. Moreover, MDS showed the central role of WSB1 in influencing the other target genes by its central location on the map. Our study is the first to show a link between WSB1 expression and other genes involved in PC progression, suggesting a novel role for WSB1 in PC progression. This network between WSB1 and EZH2 through WNT/β-catenin may have an important role in PC progression, as suggested by the association between high WSB1 expression and unfavorable prognosis in our analysis.

Downregulation of MAL2 inhibits breast cancer progression through regulating β-catenin/c-Myc axis

PURPOSE

Myelin and lymphocyte protein 2 (MAL2) is mainly involved in endocytosis under physiological conditions and mediates the transport of materials across the membranes of cell and organelle. It has been reported that MAL2 is significantly upregulated in diverse cancers. This study aimed to investigate the role of MAL2 in breast cancer (BC).

METHODS

Bioinformatics analysis and Immunohistochemical assay were applied to detect the correlation between MAL2 expression in breast cancer tissues and the prognosis of breast cancer patients. Functional experiments were carried out to investigate the role of MAL2 in vitro and in vivo. The molecular mechanisms involved in MAL2-induced β-catenin and c-Myc expression and β-catenin/c-Myc-mediated enhancement of BC progression were confirmed by western blot, β-catenin inhibitor and agonist, Co-IP and immunofluorescence colocalization assays.

RESULTS

Results from the cancer genome atlas (TCGA) and clinical samples confirmed a significant upregulation of MAL2 in BC tissues than in adjacent non-tumor tissues. High expression of MAL2 was associated with worse prognosis. Functional experiments demonstrated that MAL2 knockdown reduced the migration and invasion associating with EMT, increased the apoptosis of BC cells in vitro and reduced the metastatic capacity in vivo. Mechanistically, MAL2 interacts with β-catenin in BC cells. MAL2 silencing reduced the expression of β-catenin and c-Myc, while the β-catenin agonist SKL2001 partially rescued the downregulation of c-Myc and inhibition of migration and invasion caused by MAL2 knockdown in BC cells.

CONCLUSION

These observations provided evidence that MAL2 acted as a potential tumor promoter by regulating EMT and β-catenin/c-Myc axis, suggesting potential implications for anti-metastatic therapy for BC.

Enhanced binding of β-catenin and β-TrCP mediates LMPt's anti-CSCs activity in colorectal cancer

Cancer stem cells (CSCs), a subpopulation of tumor cells with the features of self-renewal, tumor initiation, and insensitivity to common physical and chemical agents, are the key to cancer relapses, metastasis, and resistance. Accessible CSCs inhibitory strategies are primarily based on small molecule drugs, yet toxicity limits their application. Here, we report a liposome loaded with low toxicity and high effectiveness of miriplatin, lipo-miriplatin (LMPt) with high miriplatin loading, and robust stability, exhibiting a superior inhibitory effect on CSCs and non-CSCs. LMPt predominantly inhibits the survival of oxaliplatin-resistant (OXA-resistant) cells composed of CSCs. Furthermore, LMPt directly blocks stemness features of self-renewal, tumor initiation, unlimited proliferation, metastasis, and insensitivity. In mechanistic exploration, RNA sequencing (RNA-seq) revealed that LMPt downregulates the levels of pro-stemness proteins and that the β-catenin-mediated stemness pathway is enriched. Further research shows that either in adherent cells or 3D-spheres, the β-catenin-OCT4/NANOG axis, the vital pathway to maintain stemness, is depressed by LMPt. The consecutive activation of the β-catenin pathway induced by mutant β-catenin (S33Y) and OCT4/NANOG overexpression restores LMPt's anti-CSCs effect, elucidating the key role of the β-catenin-OCT4/NANOG axis. Further studies revealed that the strengthened binding of β-catenin and β-TrCP initiates ubiquitination and degradation of β-catenin induced by LMPt. In addition,the Apc^Min/+transgenicmouse model, in which colon tumors are spontaneously formed, demonstrates LMPt's potent anti-non-CSCs activity in vivo.

Frizzled-7-targeting antibody (SHH002-hu1) potently suppresses non-small-cell lung cancer via Wnt/β-catenin signaling

Non-small-cell lung cancer (NSCLC) is one of the deadliest cancers worldwide, and metastasis is considered one of the leading causes of treatment failure in NSCLC. Wnt/β-catenin signaling is crucially involved in epithelial-mesenchymal transition (EMT), a crucial factor in promoting metastasis, and also contributes to resistance developed by NSCLC to targeted agents. Frizzled-7 (Fzd7), a critical receptor of Wnt/β-catenin signaling, is aberrantly expressed in NSCLC and has been confirmed to be positively correlated with poor clinical outcomes. SHH002-hu1, a humanized antibody targeting Fzd7, was previously successfully generated by our group. Here, we studied the anti-tumor effects of SHH002-hu1 against NSCLC and revealed the underlying mechanism. First, immunofluorescence (IF) and near-infrared (NIR) imaging assays showed that SHH002-hu1 specifically binds Fzd7⁺ NSCLC cells and targets NSCLC tissues. Wound healing and transwell invasion assays indicated that SHH002-hu1 significantly inhibits the migration and invasion of NSCLC cells. Subsequently, TOP-FLASH/FOP-FLASH luciferase reporter, IF, and western blot assays validated that SHH002-hu1 effectively suppresses the activation of Wnt/β-catenin signaling, and further attenuates the EMT of NSCLC cells. Finally, the subcutaneous xenotransplanted tumor model of A549/H1975, as well as the popliteal lymph node (LN) metastasis model, was established, and SHH002-hu1 was demonstrated to inhibit the growth of NSCLC xenografts and suppress LN metastasis of NSCLC. Above all, SHH002-hu1 with selectivity toward Fzd7⁺ NSCLC and the potential of inhibiting invasion and metastasis of NSCLC via disrupting Wnt/β-catenin signaling, is indicated as a good candidate for the targeted therapy of NSCLC.

Sphingosine kinase 1 promotes growth of glioblastoma by increasing inflammation mediated by the NF-κB /IL-6/STAT3 and JNK/PTX3 pathways

Glioblastoma (GBM) is the most challenging malignant tumor of the central nervous system because of its high morbidity, mortality, and recurrence rate. Currently, mechanisms of GBM are still unclear and there is no effective drug for GBM in the clinic. Therefore, it is urgent to identify new drug targets and corresponding drugs for GBM. In this study, in silico analyses and experimental data show that sphingosine kinase 1 (SPHK1) is up-regulated in GBM patients, and is strongly correlated with poor prognosis and reduced overall survival. Overexpression of SPHK1 promoted the proliferation, invasion, metastasis, and clonogenicity of GBM cells, while silencing SPHK1 had the opposite effect. SPHK1 promoted inflammation through the NF-κB/IL-6/STAT3 signaling pathway and led to the phosphorylation of JNK, activating the JNK-JUN and JNK-ATF3 pathways and promoting inflammation and proliferation of GBM cells by transcriptional activation of PTX3. SPHK1 interacted with PTX3 and formed a positive feedback loop to reciprocally increase expression, promote inflammation and GBM growth. Inhibition of SPHK1 by the inhibitor, PF543, also decreased tumorigenesis in the U87-MG and U251-MG SPHK1 orthotopic mouse models. In summary, we have characterized the role and molecular mechanisms by which SPHK1 promotes GBM, which may provide opportunities for SPHK1-targeted therapy.