Ubiquitin-like protein FAT10: A potential cardioprotective factor and novel therapeutic target in cancer

Cytokines-activated nuclear IKKα-FAT10 pathway induces breast cancer tamoxifen-resistance

Endocrine therapy that blocks estrogen signaling is the most effective treatment for patients with estrogen receptor positive (ER+) breast cancer. However, the efficacy of agents such as tamoxifen (Tam) is often compromised by the development of resistance. Here we report that cytokines-activated nuclear IKKα confers Tam resistance to ER+ breast cancer by inducing the expression of FAT10, and that the expression of FAT10 and nuclear IKKα in primary ER+ human breast cancer was correlated with lymphotoxin β (LTB) expression and significantly associated with relapse and metastasis in patients treated with adjuvant mono-Tam. IKKα activation or enforced FAT10 expression promotes Tam-resistance while loss of IKKα or FAT10 augments Tam sensitivity. The induction of FAT10 by IKKα is mediated by the transcription factor Pax5, and coordinated via an IKKα-p53-miR-23a circuit in which activation of IKKα attenuates p53-directed repression of FAT10. Thus, our findings establish IKKα-to-FAT10 pathway as a new therapeutic target for the treatment of Tam-resistant ER+ breast cancer.

Candidate molecular targets uncovered in mouse lifespan extension studies

INTRODUCTION

Multiple interventions have demonstrated an increase in mouse lifespan. However, non-standardized controls, sex or strain-specific factors, and insufficient focus on targets, hinder the translation of these findings into clinical applications.

AREAS COVERED

We examined the effects of genetic and drug-based interventions on mice from databases DrugAge, GenAge, the Mouse Phenome Database, and publications from PubMed that led to a lifespan extension of more than 10%, identifying specific molecular targets that were manipulated to achieve the maximum lifespan in mice. Subsequently, we characterized 10 molecular targets influenced by these interventions, with particular attention given to clinical trials and potential indications for each.

EXPERT OPINION

To increase the translational potential of mice life-extension studies to clinical research several factors are crucial: standardization of mice lifespan research approaches, the development of clear criteria for control and experimental groups, the establishment of criteria for potential geroprotectors, and focusing on targets and their clinical application. Pinpointing the targets affected by geroprotectors helps in understanding species-specific differences and identifying potential side effects, ensuring the safety and effectiveness of clinical trials. Additionally, target review facilitates the optimization of treatment protocols and the evaluation of the clinical feasibility of translating research findings into practical therapies for humans.

Loss of RNA-binding protein CELF2 promotes acute leukemia development via FAT10-mTORC1

RNA-binding proteins (RBPs) are critical regulators for RNA transcription and translation. As a key member of RBPs, ELAV-like family protein 2 (CELF2) has been shown to regulate RNA splicing and embryonic hematopoietic development and was frequently seen dysregulated in acute myeloid leukemia (AML). However, the functional role(s) of CELF2 in hematopoiesis and leukemogenesis has not been fully elucidated. In the current study, we showed that Celf2 deficiency in hematopoietic system led to enhanced HSCs self-renewal and differentiation toward myeloid cells in mice. Loss of Celf2 accelerated myeloid cell transformation and AML development in MLL-AF9-induced AML murine models. Gene expression profiling integrated with RNA immunoprecipitation sequencing (RIP-Seq), together with biochemical experiments revealed that CELF2 deficiency stabilizes FAT10 mRNA, promotes FAT10 translation, thereby increases AKT phosphorylation and mTORC1 signaling pathway activation. Notably, combination therapy with a mTORC1 inhibitor (Rapamycin) and a MA9/DOTL1 inhibitor (EPZ-5676) reduced the leukemia burden in MLL-AF9 mice lacking Celf2 in vivo. Our study elucidated a novel mechanism by which the CELF2/FAT10-AKT/mTORC1 axis regulates the proliferation of normal blood cells and the development of AML, thus providing potential therapeutic targets for myeloid leukemia suppression.

The E3 ubiquitin ligases regulate inflammation in cardiovascular diseases

Accumulating evidence has illustrated that the E3 ubiquitin ligases critically participate in the development and progression of cardiovascular diseases. Dysregulation of E3 ubiquitin ligases exacerbates cardiovascular diseases. Blockade or activation of E3 ubiquitin ligases mitigates cardiovascular performance. Therefore, in this review, we mainly introduced the critical role and underlying molecular mechanisms of E3 ubiquitin ligase NEDD4 family in governing the initiation and progression of cardiovascular diseases, including ITCH, WWP1, WWP2, Smurf1, Smurf2, Nedd4-1 and Nedd4-2. Moreover, the functions and molecular insights of other E3 ubiquitin ligases, such as F-box proteins, in cardiovascular disease development and malignant progression are described. Furthermore, we illustrate several compounds that alter the expression of E3 ubiquitin ligases to alleviate cardiovascular diseases. Therefore, modulation of E3 ubiquitin ligases could be a novel and promising strategy for improvement of therapeutic efficacy of deteriorative cardiovascular diseases.

The ubiquitin-like modifier FAT10 covalently modifies HUWE1 and strengthens the interaction of AMBRA1 and HUWE1

The ubiquitin-like modifier FAT10 is highly upregulated under inflammatory conditions and targets its conjugation substrates to the degradation by the 26S proteasome. This process termed FAT10ylation is mediated by an enzymatic cascade and includes the E1 activating enzyme ubiquitin-like modifier activating enzyme 6 (UBA6), the E2 conjugating enzyme UBA6-specific E2 enzyme 1 (USE1) and E3 ligases, such as Parkin. In this study, the function of the HECT-type ubiquitin E3 ligase HUWE1 was investigated as a putative E3 ligase and/or conjugation substrate of FAT10. Our data provide strong evidence that HUWE1 is FAT10ylated in a UBA6 and FAT10 diglycine-dependent manner in vitro and in cellulo and that the HUWE1-FAT10 conjugate is targeted to proteasomal degradation. Since the mutation of all relevant cysteine residues within the HUWE1 HECT domain did not abolish FAT10 conjugation, a role of HUWE1 as E3 ligase for FAT10ylation is rather unlikely. Moreover, we have identified the autophagy-related protein AMBRA1 as a new FAT10 interaction partner. We show that the HUWE1-FAT10 conjugate formation is diminished in presence of AMBRA1, while the interaction between AMBRA1 and HUWE1 is strengthened in presence of FAT10. This implies a putative interplay of all three proteins in cellular processes such as mitophagy.

Upregulated Ubiquitin D is a Favorable Prognostic Indicator for Rectal Cancer Patients Undergoing Preoperative Concurrent Chemoradiotherapy

Purpose

For locally advanced rectal cancer, neoadjuvant concurrent chemoradiotherapy (CCRT) allows tumor downstaging and makes curative radical proctectomy possible. However, we lack a genetic biomarker to predict cancer prognosis or treatment response. We investigated the association between ubiquitin D (UBD) expression and clinical outcomes in rectal cancer patients receiving CCRT.

Patients and Methods

We analyzed the genes associated with the protein modification process (GO:0036211) and identified the UBD gene as the most relevant among the top 7 differentially expressed genes associated with CCRT resistance. We collected tissue specimens from 172 rectal cancer patients who had received CCRT followed by a curative proctectomy. We examine the relationship between UBD expression and patient characteristics, pathological findings, and patient survival, such as metastasis-free survival (MeFS) and disease-specific survival.

Results

Upregulated UBD expression was associated with lower pre-CCRT tumor T stage (P = 0.009), lower post-CCRT tumor T stage (P < 0.001), lower post-CCRT nodal stage (P < 0.001), less vascular invasion (P = 0.015), and better tumor regression (P < 0.001). Using univariate analysis, we found that high UBD expression was correlated with better disease-free survival (DFS) (P < 0.0001), local recurrence-free survival (LRFS) (P < 0.0001) and MeFS (P < 0.0001). Moreover, multivariate analysis demonstrated that high UBD expression was associated with superior DFS (P < 0.001), LRFS (P = 0.01), and MeFS (P = 0.004).

Conclusion

UBD upregulation was linked to better clinical prognosis, favorable pathological features, and good treatment response in rectal cancer patients undergoing CCRT. These results suggest UBD is a biomarker for rectal cancer.

FAT10 is a Prognostic Biomarker and Correlated With Immune Infiltrates in Skin Cutaneous Melanoma

Background: Skin Cutaneous Melanoma (SKCM) is the deadliest cutaneous neoplasm. Previous studies have proposed ubiquitin-like protein FAT10 plays key roles in the initiation and progression of several types of human cancer, but little is known about the interrelation between FAT10 gene expression, tumor immunity, and prognosis of patients with SKCM.

Methods: Here, we first performed pan-cancer analysis for FAT10’s expression and prognosis using the Cancer Genome Atlas and the Genotype-Tissue Expression data. Subsequently, we investigated the mRNA expression level, prognostic value, and gene-gene interaction network of FAT10 in SKCM using the Oncomine databases, GEPIA, TIMER, UALCAN, and starBase. The relationship between FAT10 expression and tumor immune invasion was studied by using the TIMER database. Additionally, the expression and functional status of FAT10 in SKCM were evaluated by the single-cell RNA sequencing and CancerSEA databases.

Results: In this study, we found that FAT10 expression was increased in SKCM and was correlated with a better survival rate in patients with SKCM. Moreover, we identified FAT10 level was significantly positively associated with immune infiltrates, biomarkers of immune cells, and immune checkpoint expression, and negatively correlated with tumor cell invasion and DNA damage, indicating that increased FAT10 expression in SKCM was a favorable response to immune checkpoint inhibitors.

Conclusion: Our findings suggest that upregulation of FAT10 correlated with better prognosis and tumor immune infiltration in SKCM.

New biomarkers and therapeutic targets of human liver cancer: Transcriptomic findings

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related deaths worldwide, causing 782,000 deaths in 2018. Poor prognosis and lack of treatment are the reasons for the high mortality rate of HCC. In the current study, we conducted a comparative transcriptomic analysis, followed by a series of bioinformatics analyses, including Gene Ontology (GO) enrichment analysis and Ingenuity Pathway Analysis (IPA), aiming to unfold the detailed molecular mechanisms underlying the development of HCC. In the comparative transcriptomic analysis of 10 pairs of HCC tumoral tissues and adjunct nontumoral tissues, we identified 115 common differentially expressed genes in HCC. The GO enrichment analysis of these genes highlighted alterations in the immune response, cell proliferation and DNA damage, energetic metabolism, cell-matrix adhesion, and filament assembly in HCC. In addition, the canonical pathway analysis of IPA further showed the importance of many cell-signaling pathways involved in the carcinogenesis of HCC. The findings of this study provide a cluster of novel biomarkers and molecular therapeutic targets for HCC diagnosis and treatment.

FAT10 promotes hepatocellular carcinoma (HCC) carcinogenesis by mediating P53 degradation and acts as a prognostic indicator of HCC

Background

With the advancement of hepatocellular carcinoma (HCC) treatment technology, the treatment options for HCC patients have increased. However, due to high heterogeneity, among other reasons, the five-year survival rate of patients is still very low. Currently, gene expression prognostic models can suggest more appropriate strategies for the treatment of HCC. This study investigates the role of FAT10 in hepatocarcinogenesis and its underlying mechanism.

Methods

The expression of FAT10 was detected by immunohistochemical method using tissue arrays containing 4 specimens of patients with digestive cancer. The expression of FAT10 was determined by a tissue microarray which included 286 pairs of HCC samples and corresponding normal mucosae and was further confirmed by real-time polymerase chain reaction (PCR) and western blot. The Kaplan-Meier survival curve was used to determine the correlation of FAT10 expression with patients' recurrence and overall survival (OS) rate. In vivo, liver fibrosis, cirrhosis, and HCC models were established to assess the FAT10 expression. Moreover, FAT10 over-expressing cell lines were used to determine the molecular mechanism underlying the FAT10-induced cell proliferation and hepatocarcinogenesis by reporter gene measure, real-time PCR, and western blot. Based on TCGA database, signal pathways associated with FAT10 and HCC invasion and metastasis were analyzed by KEGG enrichment analyze.

Results

Overexpression of FAT10 in HCC was observed in this study compared with its expression in other digestive tumors. Clinicopathological analysis revealed that FAT10 expression levels were closely associated with tumor diameters and poor prognosis of HCC. This study also confirmed through in vivo experiments that the expression of FAT10 in liver fibrosis, cirrhosis, and HCC gradually increases. Further study revealed that forced FAT10 expression enhanced the growth ability of HCC cells and mediated the degradation of the critical anti-cancer protein p53, which led to carcinogenesis. Finally, 9 signal pathways related to HCC metastasis were obtained through bioinformatics analysis.

Conclusions

FAT10 may act as a proto-oncogene that facilitates HCC carcinogenesis by mediating p53 degradation, and the expression of FAT10 is negatively correlated with the prognosis of HCC patients. FAT10 is expected to become a potential combined target and prognostic warning marker for HCC treatment.