Knockdown of RNF6 inhibits gastric cancer cell growth by suppressing STAT3 signaling

The E3 ubiquitin ligase RNF6 facilitates the progression of cervical cancer by inhibiting the Hippo/Yap pathway

PURPOSE

Cervical cancer (CC), a significant global health threat, necessitates comprehensive understanding for improved therapeutic interventions. Many research indicates that dysregulation of the Hippo-YAP1 pathway leads to uncontrolled proliferation and invasion of tumor cells, promoting the progression of various cancers. This article aims to elucidate the role of RNF6 in CC and its regulation of the Hippo-YAP1 signaling pathway.

METHODS

The public tumor dataset analyses, immunohistochemistry, and western blotting were used to explore the expression of RNF6 in CC. Gain- and loss-of-function assays were conducted to elucidate the role of RNF6 in the proliferation and invasion of CC cells. Transcriptome sequencing was used to explore RNF6's role in cervical cancer, with validation of its regulation of the Hippo-YAP1 pathway through western blotting and RT-qPCR. Co-transfection of YAP overexpression plasmids into RNF6-silenced CC cells were preformed to confirm YAP1's pivotal role in RNF6-mediated CC progression. Animal experiments were preformed to further validate RNF6 interference's inhibitory effect on CC proliferation in vivo.

RESULTS

Clinical samples and bioinformatics analysis revealed high expression of RNF6 in CC, and closely associated with advanced FIGO (International Federation of Gynecology and Obstetrics) stage, larger tumor size, and poor prognosis. Cellular functional experiments demonstrate that RNF6 promotes the proliferation, invasion, and migration of CC cells, while knockdown of RNF6 yields the opposite effect. Transcriptome sequencing further reveals that RNF6 may promote CC progression through the Hippo-YAP signaling pathway. Western blotting and RT-qPCR further unveil that RNF6 enhances the upregulation of YAP1 protein levels, thereby activating downstream oncogenes CTGF and CYR61 transcription. Additionally, exogenous overexpression of YAP1 reverses the inhibitory effect of RNF6 silencing on CC proliferation and invasion. Furthermore, RNF6 interference significantly attenuates tumor growth in vivo experiments.

CONCLUSION

Our research reveals that RNF6 is highly expressed in CC, driving malignant progression by upregulating YAP1 protein expression and enhancing the transcription of downstream target genes CTGF and CYR61, offering potential therapeutic targets for CC treatment.

Pan-cancer analysis of the prognostic and immunological roles of SHP-1/ptpn6

SHP-1, a nonreceptor protein tyrosine phosphatase encoded by ptpn6, has been regarded as a regulatory protein of hematopoietic cell biology for years. However, there is now increasing evidence to support its role in tumors. Thus, the role of ptpn6 for prognosis and immune regulation across 33 tumors was investigated, aiming to explore its functional heterogeneity and clinical significance in pan-cancer. Differential expression of ptpn6 was found between cancer and adjacent normal tissues, and its expression was significantly correlated with the prognosis of tumor patients. In most cancers, ptpn6 expression was significantly associated with immune infiltration. This was further confirmed by ptpn6-related genes/proteins enrichment analysis. Additionally, genetic alterations in ptpn6 was observed in most cancers. As for epigenetic changes, it's phosphorylation levels significantly altered in 6 tumors, while methylation levels significantly altered in 12 tumors. Notably, the methylation levels of ptpn6 were significantly decreased in 11 tumors, accompanied by its increased expression in 8 of them, suggesting that the hypomethylation may be related to its increased expression. Our results show that ptpn6 plays a specific role in tumor immunity and exerts a pleiotropic effect in a variety of tumors. It can serve as a prognostic factor for some cancers. Especially in LGG, KIRC, UCS and TGCT, the increased expression of ptpn6 is associated with poor prognosis and high immune infiltration. This aids in understanding the role of ptpn6 in tumor biology, and can provide insight into presenting a potential biomarker for poor prognosis and immune infiltration in cancers.

Advantages and disadvantages of treatment of experimental ARDS by M2-polarized RAW 264.7 macrophages

Innate immunity reactions are core to any immunological process, including systemic inflammation and such extremes as acute respiratory distress syndrome (ARDS) and cytokine storm. Macrophages, the key cells of innate immunity, show high phenotypic plasticity: depending on microenvironmental cues, they can polarize into M1 (classically activated, pro-inflammatory) or M2 (alternatively activated, anti-inflammatory). The anti-inflammatory M2 macrophage polarization-based cell therapies constitute a novel prospective modality. Systemic administration of 'educated' macrophages is intended at their homing in lungs in order to mitigate the pro-inflammatory cytokine production and reduce the risks of 'cytokine storm' and related severe complications. Acute respiratory distress syndrome (ARDS) is the main mortality factor in pneumonia including SARS-CoV-associated cases. This study aimed to evaluate the influence of infusions of RAW 264.7 murine macrophage cell line polarized towards M2 phenotype on the development of LPS-induced ARDS in mouse model. The results indicate that the M2-polarized RAW 264.7 macrophage infusions in the studied model of ARDS promote relocation of lymphocytes from their depots in immune organs to the lungs. In addition, the treatment facilitates expression of M2-polarization markers Arg1, Vegfa and Tgfb and decreases of M1-polarization marker Cd38 in lung tissues, which can indicate the anti-inflammatory response activation. However, treatment of ARDS with M2-polarized macrophages didn't change the neutrophil numbers in the lungs. Moreover, the level of the Arg1 protein in lungs decreased throughtout the treatment with M2 macrophages, which is probably because of the pro-inflammatory microenvironment influence on the polarization of macrophages towards M1. Thus, the chemical polarization of macrophages is unstable and depends on the microenvironment. This adverse effect can be reduced through the use of primary autologous macrophages or some alternative methods of M2 polarization, notably siRNA-mediated.

RNF6 promotes gastric cancer progression by regulating CCNA1/CREBBP transcription

Ring finger protein 6 (RNF6) is a member of the E3 ubiquitin ligase family. Previous studies have reported the involvement of RNF6 as a ubiquitin ligase in the progression of gastric cancer (GC). However, this study found that RNF6 has a clear localization in the nucleus of GC, indicating a role other than ubiquitin ligase. Further chromatin immunoprecipitation sequencing (ChIP-seq) analysis revealed that RNF6 has DNA binding and transcriptional regulatory effects and is involved in important pathways such as tumor cell cycle and apoptosis. Cyclin A1 (CCNA1) and CREB binding protein (CREBBP) are downstream targets for RNF6 transcription regulation in GC. RNF6 binds to the promoter region of CCNA1/CREBBP and is actively regulating their expression in GC cells. Silencing CCNA1/CREBBP partially reversed the promoting effect of RNF6 overexpression on the biological function of GC cells. Our study suggests that RNF6 promotes the progression of GC by regulating CCNA1/CREBBP transcription.

UPS: Opportunities and challenges for gastric cancer treatment

Gastric cancer remains the fourth most frequently diagnosed malignancy and the fifth leading cause of cancer-related mortality worldwide owning to the lack of efficient drugs and targets for therapy. Accumulating evidence indicates that UPS, which consists of E1, E2, and E3 enzymes and proteasome, plays an important role in the GC tumorigenesis. The imbalance of UPS impairs the protein homeostasis network during development of GC. Therefore, modulating these enzymes and proteasome may be a promising strategy for GC target therapy. Besides, PROTAC, a strategy using UPS to degrade the target protein, is an emerging tool for drug development. Thus far, more and more PROTAC drugs enter clinical trials for cancer therapy. Here, we will analyze the abnormal expression enzymes in UPS and summarize the E3 enzymes which can be developed in PROTAC so that it can contribute to the development of UPS modulator and PROTAC technology for GC therapy.

Prognostic Signature Development on the Basis of Macrophage Phagocytosis-Mediated Oxidative Phosphorylation in Bladder Cancer

Background

Macrophages are correlated with the occurrence and progression of bladder cancer (BCa). However, few research has focused on the predictive relevance of macrophage phagocytosis-mediated oxidative phosphorylation (MPOP) with BCa overall survival. Herein, we aimed to propose the targeted macrophage control based on MPOP as a treatment method for BCa immunotherapy.

Methods

The mRNA expression data sets and clinical data of bladder cancer originated from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data set. A systematic study of several GEO data sets found differentially expressed macrophage phagocytosis regulators (DE-MPR) between BCa and normal tissues. To discover overall survival-associated DE-MPR and develop prognostic gene signature with performance validated based on receiver operating curves and Kaplan-Meier curves, researchers used univariate and Lasso Cox regression analysis (ROC). External validation was done with GSE13057 and GSE69795. To clarify its molecular mechanism and immune relevance, GO/KEGG enrichment analysis and tumor immune analysis were used. To find independent bladder cancer prognostic variables, researchers employed multivariate Cox regression analysis. Finally, using TCGA data set, a predictive nomogram was built.

Results

In BCa, a four-gene signature of oxidative phosphorylation composed of PTPN6, IKZF3, HDLBP, and EMC1 was found to predict overall survival. With the MPOP feature, the ROC curve showed that TCGA data set and the external validation data set performed better in predicting overall survival than the traditional AJCC stage. The four-gene signature can identify cancers from normal tissue and separate patients into the high-risk and low-risk groups with different overall survival rates. The four MPOP-gene signature was an independent predictive factor for BCa. In predicting overall survival, a nomogram integrating genetic and clinical prognostic variables outperformed AJCC staging. Multiple oncological features and invasion-associated pathways were identified in the high-risk group, which were also correlated with significantly lower levels of immune cell infiltration.

Conclusion

This paper found the MPOP-feature gene and developed a predictive nomogram capable of accurately predicting bladder cancer overall survival. The above discoveries can contribute to the development of personalized treatments and medical decisions.

Glaucocalyxin A Inhibits the Malignancies of Gastric Cancer Cells by Downregulating MDM2 and RNF6 via MiR-3658 and the SMG1-UPF mRNA Decay Pathway

Gastric cancer (GC) ranks as the most common gastrointestinal cancer and is among the leading causes of cancer death worldwide. Glaucocalyxin A (GLA), an entkauranoid diterpene isolated from Rab-dosia japonica var., possesses various bioactivities. To date, the data on the effect of GLA on GC are still minimal, and the molecular mechanisms remain largely unknown. Herein, we found that GLA could significantly inhibit the proliferation, cell adhesion, and invasion of HGT-1, SNU-1, SNU-6, and NCI-N87 GC cells in a dose-dependent manner. GLA enhanced the apoptosis of the GC cells as evidenced by the increased caspase-3 activity and the elevated levels of cleaved caspase-3 and cleaved PARP in GC cells in the presence of GLA. We then showed that the downregulation of Murine Double Minute Clone 2 (MDM2) and Ring Finger Protein 6 (RNF6) by GLA was implicated in the GLA-induced inhibition of the GC cells. Furthermore, MDM2 and RNF6 were identified as the targets of miR-3658 that was downregulated in the GC cells and upregulated by GLA. Moreover, it was shown that miR-3658 was hypermethylated in the GC cells, and GLA could rescue the expression of miR-3658 via demethylation by abrogating EZH2-mediated epigenetic silencing. In addition to the miR-3658-MDM2/RNF6 regulatory axis, activation of the SMG1-UPF mRNA decay pathway contributed to the downregulation of MDM2 and RNF6 by GLA in the GC cells. The inhibitory effect of GLA on gastric cancer and the expression of MDM2 and RNF6 was also validated in in vivo study. Our findings suggest that has the therapeutic potential for GC by downregulating oncogenes via posttranscriptional regulation.

RING-Finger Protein 6 promotes Drug Resistance in Retinoblastoma via JAK2/STAT3 Signaling Pathway

Chemotherapy is the first-line treatment for human retinoblastoma (RB), but the occurrence of drug resistance greatly limited its efficacy in practice. RING-finger protein 6 (RNF6) is an E3 ubiquitin ligase that is aberrantly upregulated in a range of cancers and plays important roles in cancer progression. However, the role of RNF6 in RB is largely unknown. In this study, we investigated the role of RNF6 in RB drug resistance. Two carboplatin-resistant RB cells, Y-79/CR and SO-Rb50/CR, were generated based on Y-79 and SO-Rb50 cells. RT-PCR and western blot analyses showed that RNF6 expression on both mRNA and protein levels was significantly increased in Y-79/CR and SO-Rb50/CR cells comparing to their parental cells. Knockdown of RNF6 using siRNA in Y-79/CR and SO-Rb50/CR cells resulted in cells sensitive to carboplatin on a RNF6 siRNA dose dependent manner. Similarly, RNF6 overexpression in parental Y-79 and SO-Rb50 cells could help cells gain resistance to carboplatin on a RNF6 expression dependent manner. Signaling pathway analyses revealed that JAK2/STAT3 pathway was involved in the RNF6-induced carboplatin resistance in RB cells. We further revealed that RNF6 expression in both Y-79 and SO-Rb50 cells could render cells resistant to multiple anti-cancer drugs including carboplatin, vincristine and etoposide, an implication of RNF6 as a biomarker for RB drug resistance. Taken together, our study has revealed that RNF6 is upregulated in drug-resistant RB cells and RNF6 promotes drug resistance through JAK2/STAT3 signaling pathway. The importance of RNF6 in RB cells drug resistance may represent this protein as a potential biomarker and treatment target for drug resistance in RB.

Construction of a circRNA-miRNA-mRNA network based on differentially co-expressed circular RNA in gastric cancer tissue and plasma by bioinformatics analysis

BACKGROUND

Increasing evidence implicates circular RNAs (circRNAs) have been involved in human cancer progression. However, the mechanism remains unclear. In this study, we identified novel circRNAs related to gastric cancer and constructed a circRNA-miRNA-mRNA network.

METHODS

Microarray datasets GSE83521 and GSE93541 were obtained from the Gene Expression Omnibus (GEO). Then, we used computational biology to identify circRNAs that were differentially expressed in both GC tissue and plasma compared to normal controls; then, we detected the expression of the selected circRNAs in gastric cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). We also identified circRNA-related candidate miRNAs and their target genes with online tools. Combining the predicted miRNAs and target mRNAs, a competing endogenous RNA regulatory network was established. Functional and pathway enrichment analyses were performed, and interactions between proteins were predicted by using String and Cytoscape. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to elucidate the possible functions of these differentially expressed circRNAs. The regulatory network constructed using the microarray datasets (GSE83521 and GSE93541) contained three differentially co-expressed circRNAs (DECs). A circRNA-miRNA-mRNA network was constructed based on 3 circRNAs, 43 miRNAs and 119 mRNAs.

RESULTS

GO and KEGG analysis showed that the regulation of apoptotic signaling pathway and PI3K-Akt signaling pathway were highest degrees of enrichment respectively. We established a protein-protein interaction (PPI) network consisting of 165 nodes and 170 edges and identified hub genes by using MCODE plugin in Cytoscape. Furthermore, a core circRNA-miRNA-mRNA network was constructed based on hub genes. Hsa_circ_0001013 was finally determined to play an important role in the pathogenesis of GC according to the core circRNA-miRNA-mRNA network.

CONCLUSIONS

We propose a new circRNA-miRNA-mRNA network that is associated with the pathogenesis of GC. The network may become a new molecular biomarker and could be used to develop potential therapeutic strategies for gastric cancer.

Functions of RNF Family in the Tumor Microenvironment and Drugs Prediction in Grade II/III Gliomas

Increasing evidence has demonstrated that RING finger (RNF) proteins played a vital role in cellular and physiological processes and various diseases. However, the function of RNF proteins in low-grade glioma (LGG) remains unknown. In this study, 138 RNF family members revealed their role in LGG. The TCGA database was used as the training cohort; two CGGA databases and GSE108474 were selected as external validation cohorts. Patients were grouped into cluster 1 and cluster 2, both in the training and validation cohorts, using consensus clustering analysis. The prognosis of patients in cluster 1 is significantly better than that in cluster 2. Meanwhile, biofunction prediction was further introduced to explore the potential mechanisms that led to differences in survival outcomes. Patients in Cluster 2 showed more complicated immunocytes infiltration and highly immunosuppressive features than cluster 1. Enrichment pathways such as negative regulation of mast cell activation, DNA replication, mismatch repair, Th17 cell differentiation, antigen processing and presentation, dendritic cell antigen processing and presentation, dendritic cell differentiation were also enriched in cluster 2 patients. For the last, the main contributors were distinguished by employing a machine learning algorithm. A lot of targeted and small molecule drugs that are sensitive to patients in cluster 2 were predicted. Importantly, we discovered TRIM8, DTX2, and TRAF5 as the most vital contributors from the RNF family, which were related to immune infiltration in LGG tumor immune landscape. In this study, we demonstrated the predicted role of RNF proteins in LGG. In addition, we found out three markers among RNF proteins that are closely related to the immune aspects of LGG, which might serve as novel therapeutic targets for immunotherapy in the future.

RNF6 promotes colorectal cancer invasion and migration via the Wnt/β-catenin pathway by inhibiting GSK3β activity

BACKGROUND

The purpose of this study was to explore the molecular mechanism underlying the interaction between ring finger protein 6 (RNF6) and glycogen synthase kinase 3β (GSK3β) in colorectal cancer (CRC).

METHODS

In this study, cell models of overexpressed or silenced RNF6 were established by liposome transfection, and IM-12 was used as the inhibitor of GSK3β. Real-time quantitative PCR and western blots were used to detect the expression of RNF6, p-GSK3β, GSK3β, and β-catenin, and MTT assays were used to quantify cell proliferation. The tumorigenicity of cells was observed by plate clonal formation assay; the invasiveness of cells was examined in Transwell Boyden chambers, and the migratory capacity of cells was tested by scratch wound assays. The rat CRC model was induced by AOM/DSS, in which we verified activity in the Wnt/β-catenin pathway by examining GSK3β phosphorylation.

RESULTS

RNF6 was upregulated in CRC samples and cell lines. Silencing or overexpressing RNF6 in colorectal cancer cells inhibited or promoted, respectively, the proliferation, tumorigenicity, invasion and migration of CRC cells, as well as expression of p-GSK3β, GSK3β and β-catenin. IM-12 reversed the Wnt/β-catenin-activated state change induced by RNF6 silencing and the inhibition of cell proliferation, tumorigenicity, invasion and migration. The same results were observed in vivo in the rat CRC model.

CONCLUSIONS

Overexpression of RNF6 in CRC increased the GSK3β phosphorylation level, which led to activation of the Wnt/β-catenin pathway and promoted the invasion and migration of CRC cells, suggesting that RNF6 may be a novel target for the treatment of CRC.

Knockdown of RNF6 inhibits HeLa cervical cancer cell growth via suppression of MAPK/ERK signaling

Ring finger protein 6 (RNF6) is implicated in various human malignancies, but its function in cervical cancer (CC) is incompletely understood. Here, we explored the biological significance of RNF6 in HeLa CC cells and the underlying regulatory mechanisms. The expression of RNF6 was observed to be high in both primary tissues and CC cells. RNF6 promoted HeLa CC cell growth. Knockdown of RNF6 in CC cells resulted in suppression of proliferation and promotion of apoptosis. Moreover, elevation of RNF6 had an adverse effect on the prognosis of CC. Subsequent analyses showed that these effects may be mediated via activation of ERK signaling. These findings provide evidence that the knockdown of RNF6 suppresses the MAPK/ERK pathway to regulate the growth of CC cells, which suggests that RNF6 may have potential as a target for diagnosis and treatment for CC.

miR-203a suppresses cell proliferation by targeting RING-finger protein 6 in colorectal cancer

Colorectal cancer (CRC) is one of most common cancers worldwide. Although miR-203a is reported as a tumor suppressor involved in cell progression in some cancers, the role of miR-203a in CRC is still controversial and the underling mechanism of miR-203a in CRC remains unclear. Here, we demonstrated that low expression of miR-203a had poorer survival in CRC patients. miR-203a was down-regulated in most human colon cancer cells. Overexpression of miR-203a could inhibit colon cancer cell proliferation and arrest cell cycle in G1 phase. Bioinformatics and dual luciferase reporter assay confirmed that RING-finger protein 6 (RNF6) was a target gene of miR-203a. Silencing RNF6 inhibited cell proliferation and arrest cell cycle in G1 phase. RNF6 overexpression reversed the effects of miR-203a overexpression in colon cancer cells. Taken together, our data indicate that miR-203a inhibits colon cancer cell proliferation by targeting RNF6, offer novel insights into the regulatory network of miR-203a-modulated cell cycle and proliferation, and suggest that miR-203a a potential therapeutic target in CRC treatment.

Gene commander in the trash heap: Transcriptional regulation and ubiquitination modification mediated by RNF6 in carcinogenesis

RING finger protein 6 (RNF6), a RING finger protein, has been identified as a potential tumor promoter in several cancers. However, the exact mechanism of RNF6 in cancer remains elusive. As in various diseases, RNF6 may be involved in regulating cell growth, cell proliferation, invasion, cell cycle progression, apoptosis and cell adhesion through E3 ligase-mediated ubiquitination. Thus, the research on RNF6 is mainly focused on the ubiquitination of RNF6 in recent years. This article summarizes the role of RNF6 ubiquitination in various physiological and pathological mechanisms, such as Akt/mTOR signaling pathway, Wnt/β-catenin pathway, RNF6/ERα/Bcl-xL axis, and provides knowledge and understanding for the treatment of diseases.

Roles of E3 ubiquitin ligases in gastric cancer carcinogenesis and their effects on cisplatin resistance

Although gastric cancer (GC) is one of the most common cancers with high incidence and mortality rates, its pathogenesis is still not elucidated. GC carcinogenesis is complicated and involved in the activation of oncoproteins and inactivation of tumor suppressors. The ubiquitin-proteasome system (UPS) is crucial for protein degradation and regulation of physiological and pathological processes. E3 ubiquitin ligases are pivotal enzymes in UPS, containing various subfamily proteins. Previous studies report that some E3 ligases, including SKP2, CUL1, and MDM2, act as oncoproteins in GC carcinogenesis. On the other hand, FBXW7, FBXL5, FBXO31, RNF43, and RNF180 exert as tumor suppressors in GC carcinogenesis. Moreover, E3 ligases modulate cell growth, cell apoptosis, and cell cycle; thus, it is complicated to confer cisplatin resistance/sensitivity in GC cells. The intrinsic and acquired cisplatin resistance limits its clinical application against GC. In this review, we explore oncogenic and tumor suppressive roles of E3 ligases in GC carcinogenesis and focus on the effects of E3 ligases on cisplatin resistance in GC cells, which will provide novel therapeutic targets for GC therapy, especially for cisplatin-resistant patients.

Inhibition of RNF6 alleviates traumatic brain injury by suppressing STAT3 signaling in rats

BACKGROUND

Traumatic brain injury (TBI) has ranked as one of the leading causes of disability and death in the world. The neuroinflammation mediated by signal transducer and activator of transcription 3 (STAT3) signaling during the progression of TBI leads to long-term neurodegeneration. Ring finger protein 6 (RNF-6) is an E3 ubiquitin ligase and can regulate the activity of STAT3 signaling pathway by targeting its inhibitors. However, the mechanism underlying this process in TBI remains poorly understood.

METHODS

In this research, cortical impact injury was used to construct the TBI rat model. Western blot assay was performed to evaluate the protein levels of RNF6, Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1), and STAT3/pSTAT3. QRT-PCR assay was performed to assess the RNA levels of RNF6 and other cytokines. The neural function of TBI rats was estimated by modified Neurological Severity Scores test.

RESULTS

The expression of RNF-6 was up-regulated in the brain tissues of TBI rats. Down-regulation of RNF6 alleviated the symptoms and improved the neural recovery postinjury in TBI rats. Inhibition of RNF6 suppressed the cerebral inflammation by up-regulating the protein level of SHP-1 and down-regulating the phosphorylation level of STAT3.

CONCLUSION

Inhibition of RNF6 alleviated TBI by suppressing the STAT3 signaling in TBI rats.

RNF6 as an Oncogene and Potential Therapeutic Target—A Review

The RNF6 gene encodes Ring Finger Protein 6 (RNF6), which functions as a ubiquitin ligase. Its functions are not entirely known, but research shows that it is involved in human cancer development. Initially, this gene was considered to be a tumor suppressor. Numerous statistical analyses on cell lines and animals indicate, however, that RNF6 functions as an oncogene, involved in signaling pathways, including SHP1/STAT3, AKT/mTOR, Wnt/β-catenin, or ERα/Bcl-xL. Due to this fact, it has become a potential prognostic factor and therapeutic target. Studies in tumor cells and model organisms using inhibitors such as total saponins from Paris forrestii (TSPf), ellagic acid, or microRNA molecules show the effectiveness of inhibiting RNF6, and through it, the pathways of tumor cell proliferation. The results of the currently available studies are promising, but the function of RNF6 is not fully understood. More research is needed to assess the role of RNF6 and to check the safety and efficacy of inhibitors.

The bioflavonoid troxerutin prevents gestational hypertension in mice by inhibiting STAT3 signaling

Gestational hypertension is a high-risk disease for women, and the current treatments have limited efficacies. Here, we aimed to evaluate troxerutin, which is a natural monomer of flavone, in the treatment of gestational hypertension. Pregnant mice with or without pregnancy-induced hypertension (PIH) were treated with troxerutin (20 and 40 mg/kg) or vehicle. Blood pressure and proteinuria were monitored during treatment. The expression of vasodilation converting enzyme (VCE), angiotensin, TNFα, IL-6, IL-1β and IL-10 was measured by enzyme-linked immunosorbent assay (ELISA). Oxidative stress was assessed by measuring the reactive oxygen species (ROS) levels and antioxidant enzyme concentrations. Western blot analysis was used to assess the expression of p-STAT3, STAT3, SHP-1, and RNF6. Troxerutin reduced blood pressure and the expression of VCE, angiotensin, urinary protein and pro-inflammatory cytokines in a dose-dependent manner while increasing the expression of anti-inflammatory cytokines. The levels of ROS were decreased, and the levels of antioxidant enzymes were increased. Troxerutin treatment significantly suppressed STAT3/RNF6 signaling. Overexpression of RNF6 attenuated the effects of troxerutin in ameliorating inflammation and oxidative stress. Our data support the use of troxerutin for reducing gestational hypertension due to the role of troxerutin in reducing inflammation and oxidative stress.

Functional roles of E3 ubiquitin ligases in gastric cancer

To date, >650 E3 ubiquitin ligases have been described in humans, including >600 really interesting new genes (RINGs), 28 homologous to E6-associated protein C-terminus (HECTs) and several RING-in-between-RINGs. They are considered key regulators and therapeutic targets of many types of human cancers, including gastric cancer (GC). Among them, some RING and HECT E3 ligases are closely related to the proliferation, infiltration and prognosis of GC. During the past few years, abnormal expressions and functions of many E3 ligases have been identified in GC. However, the functional roles of E3 ligases in GC have not been fully elucidated. The present article focuses on the functional roles of E3 ligases related to the proteasome in GC. In this comprehensive review, the latest research progress on E3 ligases involved in GC and elaborate their structure, classification, functional roles and therapeutic value in GC was summarized. Finally, 30 E3 ligases that serve essential roles in regulating the development of GC were described. Some of these ligases may serve as oncogenes or tumor suppressors in GC, whereas the pathological mechanism of others needs further study; for example, constitutive photomorphogenic 1. In conclusion, the present review demonstrated that E3 ligases are crucial tumor regulatory factors and potential therapeutic targets in GC. Therefore, more studies should focus on the therapeutic targeting of E3 ligases in GC.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.

The Analysis of PTPN6 for Bladder Cancer: An Exploratory Study Based on TCGA

PTPN6 (protein tyrosine phosphatase nonreceptor type 6), a tyrosine phosphatase, is known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. Previous studies have demonstrated that PTPN6 expression is relatively elevated in several malignancies. However, the role of PTPN6 in bladder cancer (BC) remains unclear. The purpose of this study was to explore the prognostic value of PTPN6 in BC. RNA-seq data from The Cancer Genome Atlas (TCGA) was used to identify the expression level of PTPN6 in BC. The relationship between clinical pathologic features and PTPN6 were analyzed with the Wilcoxon signed-rank test. The prognostic and predictive value of PTPN6 was evaluated by survival analysis and nomogram. Gene Set Enrichment Analysis (GSEA) was conducted to explore the potential molecular mechanisms of PTPN6 in BC. Finally, Tumor Immune Estimation Resource (TIMER) was applied to investigate the relationship between PTPN6 and immune cell infiltration in the tumor microenvironment. Results indicated that PTPN6 was overexpressed in BC tissues compared with normal bladder tissues and was significantly correlated with grade, stage, T, and N. Survival analysis showed that low expression of PTPN6 was significantly related to the poor overall survival (OS) in BC patients. Coexpression analysis showed that PTPN6 and TNFRSF14 (Tumor necrosis factor receptor superfamily member 14) have a close correlation in BC. GSEA showed that multiple cancer-associated signaling pathways are differentially enriched in the PTPN6 high expression phenotype. Moreover, the expression level of PTPN6 was positively associated with the infiltration of B cells, CD4+T cells, dendritic cells, and neutrophils and negatively associated with CD8+ T cells and macrophages in BC. In conclusion, we identified that PTPN6 may be a novel prognostic biomarker in BC based on the TCGA database. Further clinical trials are needed to confirm our observations and mechanisms underlying the prognostic value of PTPN6 in BC also deserve further experimental exploration.

Ellagic acid induces esophageal squamous cell carcinoma cell apoptosis by modulating SHP-1/STAT3 signaling

Ellagic acid (EA) has been reported to have antiproliferative and antioxidant properties, but its function in esophageal squamous cell carcinoma (ESCC) has not been investigated yet. In the current study, EA was found have a significant anti-tumor activity in ESCC. In specific, EA inhibited ESCC cell survival in both of a concentration- and time-dependent manner. And our results showed that EA promoted ESCC cell apoptosis, including inducing the cleavages of PARP, and inhibiting the expression of anti-apoptotic proteins. In mechanistic, EA markedly suppressed STAT3-driven luciferase activity, and inhibited both of the endogenous and cytokines-induced STAT3 activation in ESCC cells. Further investigations indicated that EA could significantly upregulate SHP-1 expression, a negative modulator of STAT3 signaling. In contrast, knockdown of SHP-1 could attenuate the effects of EA on inhibiting ESCC cell survival. Moreover, we found that EA could inhibit RNF6 expression, an E3 of SHP-1, and overexpressing RNF6 could also significantly attenuate the effects of EA on inhibiting ESCC cell survival, which further revealed that EA could inhibit STAT3 signaling by modulating RNF6/SHP-1 axis. Our present study indicated that EA could be as a novel STAT3 inhibitor for the treatment of ESCC.

Overexpression of tripartite motif containing 26 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

It has been reported that tripartite motif containing 26 (TRIM26) is involved in the tumorigenesis of some cancers, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, we found that TRIM26 was markedly down-regulated in both of NSCLC tumor tissues and cell lines. Additionally, high expression of TRIM26 in NSCLC patients predicted a positive index for patients' overall survival. What is more, overexpression of TRIM26 significantly suppressed NSCLC cell growth. Our further studies indicated that overexpression of TRIM26 inhibited the phosphorylation of PI3K p85 and AKT. And overexpressed TRIM26 regulated cell cycle-related genes' expression, including downregulating CDK4, Cyclin A, Cyclin D1, Cyclin D3, and Cyclin E, and upregulating p27 expression. Finally, we found that TRIM26 up-regulated PTEN expression by stabilizing PTEN protein in NSCLC cells. Collectively, our present study indicated that TRIM26 was decreased in NSCLC and overexpression of TRIM26 inhibited NSCLC cell growth by suppressing PI3K/AKT pathway, which suggested that TRIM26 could be as a potential target for the treatment of NSCLC in the future.

Iduna protects HT22 cells by inhibiting parthanatos: The role of the p53-MDM2 pathway

Traumatic brain injury (TBI) is common and often fatal in current times. The role of poly(adenosine diphosphate-ribose) polymerase (PARP)-induced cell death (parthanatos) in TBI has not been well studied. Our past study showed that oxidative stress-induced cell death includes parthanatos by confirming the occurrence of PARP activation and nuclear translocation of apoptosis-inducing factor (AIF). As oxidative stress plays a key role in pathological progression after TBI, we believe TBI may also be alleviated by the expression of Iduna, which is the only known endogenous regulator of parthanatos. Thus, a transection model in HT-22 cells was established for present study. Downregulation of Iduna aggravated the cell damage caused by mechanical cell injury, whereas upregulation of Iduna reduced mitochondrial dysfunction induced by mechanical cell injury but exerted no effect on apoptosis associated with mitochondrial dysfunction. By contrast, Iduna prevented parthanatos by reducing PARP activation and nuclear translocation of AIF. We also investigated 2 novel p53-MDM2 pathway inhibitors, AMG 232 and Nutlin-3, which substantially reduced the protective effects of Iduna. These findings indicate that Iduna might prevent TBI by specifically inhibiting parthanatos and promoting mitochondrial function, with the p53-MDM2 pathway playing a critical role.

Ubiquitin-specific protease 44 inhibits cell growth by suppressing AKT signaling in non-small cell lung cancer

Ubiquitin-specific protease 44 (USP44) has been reported as a tumor suppressor or promoter in some tumors, but its function in non-small cell lung cancer (NSCLC) is still unclear. In this study, USP44 was found significantly downregulated in both of NSCLC tissues and cell lines, and low expression of USP44 predicted a poor prognosis for NSCLC patients. Overexpression of USP44 markedly downregulated the expression levels of Cyclin D1 and CDK4, but upregulated p53 expression, as a result of which, suppressing the cell growth of NSCLC cells. Further studies indicated that overexpression of USP44 significantly inhibited the phosphorylation of AKT, and its down-stream signals, including mTOR and P70S6K. Moreover, overexpression of USP44 increased PTEN protein but not its mRNA levels, which suggested that USP44 inhibited AKT signaling by stabilizing PTEN in NSCLC cells. In conclusion, we demonstrated that USP44 showed prior evidence of a tumor suppressive function in NSCLC cells, and inhibited NSCLC cell growth by suppressing AKT signaling, suggesting that USP44 could be as a novel target for NSCLC therapy.

Ubiquitin specific peptidase 49 inhibits non-small cell lung cancer cell growth by suppressing PI3K/AKT signaling

Ubiquitin specific peptidase 49 (USP49) has been reported as a tumor suppressor in several tumors, but its function and molecular mechanism in non-small cell lung cancer (NSCLC) are still unknown. In this study, USP49 was found downregulated in NSCLC primary tissues and cell lines, and high USP49 predicted a positive index for the overall survival of NSCLC patients. Overexpression of USP49 downregulated the expression levels of Cyclin D1, and upregulated p53 expression. Further flow cytometry analysis showed that overexpressed USP49 induced cell cycle arrest at G0/G1 phase. As a result, overexpression of USP49 significantly inhibited cell growth of NSCLC cells. In mechanism, overexpression of USP49 inhibited PI3K/AKT signaling, but knockdown of USP49 enhanced this signaling. Further studies indicated that USP49 deubiquitinated PTEN and stabilized PTEN protein, which suggested that USP49 inhibited PI3K/AKT signaling by stabilizing PTEN in NSCLC cells. In conclusion, we demonstrated that USP49 was functional in NSCLC cells, and inhibited NSCLC cell growth by suppressing PI3K/AKT signaling, suggesting that USP49 could be as a novel target for NSCLC therapy.