Siah1 in cancer and nervous system diseases (Review)

SIAH3 is frequently epigenetically silenced in cancer and regulates mitochondrial metabolism

Of the seven in absentia homologue (SIAH) family, three members have been identified in the human genome. In contrast to the E3 ubiquitin ligase encoding SIAH1 and SIAH2, little is known on the regulation and function of SIAH3 in tumorigenesis. In this study, we reveal that SIAH3 is frequently epigenetically silenced in different cancer entities, including cutaneous melanoma, lung adenocarcinoma and head and neck cancer. Low SIAH3 levels correlate with an impaired survival of cancer patients. Additionally, induced expression of SIAH3 reduces cell proliferation and induces cell death. Functionally, SIAH3 negatively affects cellular metabolism by shifting cells form aerobic oxidative phosphorylation to glycolysis. SIAH3 is localized in the mitochondrion and interacts with proteins involved in mitochondrial ribosome biogenesis and translation. We also report that SIAH3 interacts with ubiquitin ligases, including SIAH1 or SIAH2, and is degraded by them. These results suggest that SIAH3 acts as an epigenetically controlled tumor suppressor by regulating cellular metabolism through the inhibition of oxidative phosphorylation.

SIAH1 Promotes the Pyroptosis of Cardiomyocytes in Diabetic Cardiomyopathy via Regulating IκB-α/NF-κВ Signaling

Inflammation-mediated dysfunction of cardiomyocytes is the main cause of diabetic cardiomyopathy (DCM). The present study aimed to investigate the roles of siah E3 ubiquitin protein ligase 1 (SIAH1) in DCM. The online dataset GSE4172 was used to analyze the differentially expressed genes in myocardial inflammation of DCM patients. RT-qPCR was conducted to detect mRNA levels. Enzyme-Linked Immunosorbent Assay (ELISA) was performed to detect cytokine release. Western blot was used to detect protein expression. Lactate dehydrogenase (LDH) assay was used to determine cytotoxicity. In vitro ubiquitination assay was applied to determine the ubiquitination of nuclear factor kappa B inhibitor alpha (1κВ-α). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was used to detect the death of cardiomyocytes. Flow cytometry was applied for determining cardiomyocyte pyroptosis. The results showed that SIAH1 was overexpressed in human inflammatory cardiomyopathy. High expression of SIAH1 was associated with inflammatory response. SIAH1 was also overexpressed lipopolysaccharide (LPS)-induced inflammatory cardiomyopathy model in vitro. However, SIAH1 knockdown suppressed the inflammatory-related pyroptosis of cardiomyocytes. SIAH1 promoted the ubiquitination of 1κВ-α and activated nuclear factor kappa В (NF-κВ) signaling, which promoted the pyroptosis of cardiomyocytes. In conclusion, SIAH1 exacerbated the progression of human inflammatory cardiomyopathy via inducing the ubiquitination of 1κВ-α and activation of NF-κВ signaling. Therefore, SIAHI/IκB-α/NF-κB signaling may be a potential target for human inflammatory cardiomyopathy.

A Mouse-Specific Model to Detect Genes under Selection in Tumors

The mouse is a widely used model organism in cancer research. However, no computational methods exist to identify cancer driver genes in mice due to a lack of labeled training data. To address this knowledge gap, we adapted the GUST (Genes Under Selection in Tumors) model, originally trained on human exomes, to mouse exomes via transfer learning. The resulting tool, called GUST-mouse, can estimate long-term and short-term evolutionary selection in mouse tumors, and distinguish between oncogenes, tumor suppressor genes, and passenger genes using high-throughput sequencing data. We applied GUST-mouse to analyze 65 exomes of mouse primary breast cancer models and 17 exomes of mouse leukemia models. Comparing the predictions between cancer types and between human and mouse tumors revealed common and unique driver genes. The GUST-mouse method is available as an open-source R package on github.

Roles of NOLC1 in cancers and viral infection

BACKGROUND

The nucleolus is considered the center of metabolic control and an important organelle for the biogenesis of ribosomal RNA (rRNA). Nucleolar and coiled-body phosphoprotein 1(NOLC1), which was originally identified as a nuclear localization signal-binding protein is a nucleolar protein responsible for nucleolus construction and rRNA synthesis, as well as chaperone shuttling between the nucleolus and cytoplasm. NOLC1 plays an important role in a variety of cellular life activities, including ribosome biosynthesis, DNA replication, transcription regulation, RNA processing, cell cycle regulation, apoptosis, and cell regeneration.

PURPOSE

In this review, we introduce the structure and function of NOLC1. Then we elaborate its upstream post-translational modification and downstream regulation. Meanwhile, we describe its role in cancer development and viral infection which provide a direction for future clinical applications.

METHODS

The relevant literatures from PubMed have been reviewed for this article.

CONCLUSION

NOLC1 plays an important role in the progression of multiple cancers and viral infection. In-depth study of NOLC1 provides a new perspective for accurate diagnosis of patients and selection of therapeutic targets.

SIAH1/CTR9 axis promotes the epithelial-mesenchymal transition of hepatocellular carcinoma

SIAH1 has been reported to participate in several human cancers, including hepatocellular carcinoma (HCC). However, the effect of SIAH1 on the epithelial-mesenchymal transition (EMT) has not been reported in HCC cells. Here, we discovered the inhibitory effect of SIAH1 on HCC cell migration and invasion, which was related with regulating EMT. Molecularly, a yeast two-hybrid experiment indicated that Cln Three Requiring 9 (CTR9) was a potential interacting protein of SIAH1, which was further verified by co-immunoprecipitation assays. Furthermore, SIAH1 inhibited the EMT of HCC cells through negatively regulating CTR9. Importantly, CTR9 was ubiquitinated and degraded by SIAH1 via the proteasome pathway in HCC cells. Additionally, it was showed that SIAH1 mainly mediated the K48-linked polyubiquitination on CTR9. Finally, the protein level of CTR9 was found to be inversely correlated with SIAH1 in human HCC tissues. Summed up all together, these findings reveal that SIAH1/CTR9 axis promotes the EMT of HCC cells and is a promising therapeutic target for HCC therapy.

FBXO7, a tumor suppressor in endometrial carcinoma, suppresses INF2-associated mitochondrial division

Endometrial carcinoma (ECa) is the most common malignant gynecological cancer, with an increased incidence and fatality rate worldwide, while the pathogenesis is still largely unknown. In this study, we confirmed that FBXO7, a gene coding FBXO7 E3 ubiquitin ligase, is significantly downregulated and mutated (5.87%; 31/528) in ECa specimens, and the abnormal low expression and mutations of FBXO7 are associated with the occurrence of ECa. We also identify the excessive expression of INF2 protein, a key factor that triggers mitochondrial division by recruiting the DRP1 protein, and the elevated INF2 protein is significantly negatively correlated with the low FBXO7 protein in ECa specimens. Mechanistically, FBXO7 restrains ECa through inhibiting INF2-associated mitochondrial division via FBXO7-mediated ubiquitination and degradation of INF2. Moreover, we found that ECa-associated FBXO7 mutants are defective in the ubiquitination and degradation of INF2, promoting ECa cells proliferation, migration and apoptosis inhibition via inducing mitochondrial hyper-division. In addition, we found that it could reverse FBXO7 deletion or ECa-associated FBXO7 mutants-induced proliferation, migration, apoptosis inhibition and mitochondrial hyper-division of ECa cells by INF2 or DNM1L knockdown, or DRP1 inhibitor Mdivi-1. In summary, our study shows that FBXO7 acts as a novel tumor suppressor in ECa by inhibiting INF2-DRP1 axis-associated mitochondrial division through the ubiquitination and degradation of INF2 while the effect is destroyed by ECa-associated FBXO7 and INF2 mutants, highlights the key role of FBXO7-INF2-DRP1 axis in ECa tumorigenesis and provides a new viewpoint to treat ECa patients with FBXO7 deletion or mutations by targeting INF2-DRP1 axis-associated mitochondrial division.

A nomogram for predicting prognosis of multiple myeloma patients based on a ubiquitin-proteasome gene signature

BACKGROUND

Multiple myeloma (MM) is a malignant hematopoietic disease that is usually incurable. However, the ubiquitin-proteasome system (UPS) genes have not yet been established as a prognostic predictor for MM, despite their potential applications in other cancers.

METHODS

RNA sequencing data and corresponding clinical information were acquired from Multiple Myeloma Research Foundation (MMRF)-COMMPASS and served as a training set (n=787). Validation of the prediction signature were conducted by the Gene Expression Omnibus (GEO) databases (n=1040). To develop a prognostic signature for overall survival (OS), least absolute shrinkage and selection operator regressions, along with Cox regressions, were used.

RESULTS

A six-gene signature, including KCTD12, SIAH1, TRIM58, TRIM47, UBE2S, and UBE2T, was established. Kaplan-Meier survival analysis of the training and validation cohorts revealed that patients with high-risk conditions had a significantly worse prognosis than those with low-risk conditions. Furthermore, UPS-related signature is associated with a positive immune response. For predicting survival, a simple to use nomogram and the corresponding web-based calculator (https://jiangyanxiamm.shinyapps.io/MMprognosis/) were built based on the UPS signature and its clinical features. Analyses of calibration plots and decision curves showed clinical utility for both training and validation datasets.

CONCLUSIONS

As a result of these results, we established a genetic signature for MM based on UPS. This genetic signature could contribute to improving individualized survival prediction, thereby facilitating clinical decisions in patients with MM.

The role of EphA7 in different tumors

Ephrin receptor A7 (EphA7) is a member of the Eph receptor family. It is widely involved in signal transduction between cells, regulates cell proliferation and differentiation, and participates in developing neural tubes and brain. In addition, EphA7 also has a dual role of tumor promoter and tumor suppressor. It can participate in cell proliferation, migration and apoptosis through various mechanisms, and affect tumor differentiation, staging and prognosis. EphA7 may be a potential diagnostic marker and tumor treatment target. This article reviews the effects of EphA7 on a variety of tumor biological processes and pathological characteristics, as well as specific effects and regulatory mechanisms.