TRIB3 Stabilizes High TWIST1 Expression to Promote Rapid APL Progression and ATRA Resistance

Diverse functions of Tribbles homolog 3 in cancers and its potential as a therapeutic target

Currently, cancer is the second leading cause of death worldwide, and potential targeted drugs and molecular pathways for cancer development and progression have been a hot research topic worldwide. In recent years, the importance of the kinase superfamily in diseases has been well demonstrated by studies on various molecular mechanisms of kinases and the successful application of their inhibitors in diseases. Pseudokinases are members of the kinase superfamily, which have been increasingly documented to play a crucial role in cancers year after year. As a member of pseudokinases, tribbles homolog 3 (TRIB3) also exerts diverse functions in different cancers through different interacting proteins and molecular pathways, especially in tumor immunity, stemness, drug resistance, metabolism, and autophagy. In addition, peptide drugs targeting TRIB3 have high specificity in preclinical studies, which shows great promise for TRIB3 application in diseases including cancers. In this review, we dissect diverse functions played by TRIB3 in different cancers, describing the underlying mechanisms in detail. Notably, inhibitors and agonists currently available for TRIB3 are discussed, indicating the potential for TRIB3 as a therapeutic target.

TRIB3 promotes the progression of renal cell carcinoma by upregulating the lipid droplet-associated protein PLIN2

Abnormal lipid metabolism and lipid accumulation are characteristic hallmarks of renal cell carcinoma (RCC). While there is prior evidence closely linking such lipid accumulation within RCC cells and consequent tumorigenesis, the mechanisms underlying this process remain incompletely understood. In this study, a series of bioinformatics analyses were initially performed by screening RCC databases and gene sets, ultimately leading to the identification of TRIB3 as an oncogene that functions as a central regulator of lipid metabolism. TRIB3 overexpression was observed in both RCC patient tumor tissues and cell lines, and this upregulation was correlated with a worse RCC patient prognosis. When TRIB3 was knocked down, this resulted in a reduction in lipid accumulation and the consequent induction of endoplasmic reticulum (ER) stress-related apoptotic cell death. At the molecular level, interactions between TRIB3 and PLIN2 were found to abrogate TEB4-mediated PLIN2 ubiquitination and consequent degradation, thus maintaining higher PLIN2 expression levels. This simultaneously helps facilitate the accumulation of lipids while preserving ER homeostasis, thus driving accelerated RCC tumor progression. This TRIB3-PLIN2 axis thus represents a promising new target for efforts to treat RCC.

Ubiquitin-specific protease 5 promotes bladder cancer progression through stabilizing Twist1

Aberrant activation of the epithelial-mesenchymal transition (EMT) pathway drives the development of solid tumors, which is precisely regulated by core EMT-related transcription factors, including Twist1. However, the expression pattern and regulatory mechanism of Twist1 in the progression of bladder cancer is still unclear. In this study, we explore the role of Twist1 in the progression of bladder cancer. We discovered that the EMT regulon Twist1 protein, but not Twist1 mRNA, is overexpressed in bladder cancer samples using RT-qPCR, western blot and immunohistochemistry (IHC). Mechanistically, co-immunoprecipitation (Co-IP) coupled with liquid chromatography and tandem mass spectrometry identified USP5 as a binding partner of Twist1, and the binding of Twist1 to ubiquitin-specific protease 5 (USP5) stabilizes Twist through its deubiquitinase activity to activate the EMT. Further studies found that USP5 depletion reduces cell proliferation, invasion and the EMT in bladder cancer cells, and ectopic expression of Twist1 rescues the adverse effects of USP5 loss on cell invasion and the EMT. A xenograft tumor model was used to reconfirmed the inhibitor effect of silencing USP5 expression on tumorigenesis in vivo. In addition, USP5 protein levels are significantly elevated and positively associated with Twist1 levels in clinical bladder cancer samples. Collectively, our study revealed that USP5-Twist1 axis is a novel regulatory mechanism driving bladder cancer progression and that approaches targeting USP5 may become a promising cancer treatment strategy.

Cellular hierarchy insights reveal leukemic stem-like cells and early death risk in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) represents a paradigm for targeted differentiation therapy, with a minority of patients experiencing treatment failure and even early death. We here report a comprehensive single-cell analysis of 16 APL patients, uncovering cellular compositions and their impact on all-trans retinoic acid (ATRA) response in vivo and early death. We unveil a cellular differentiation hierarchy within APL blasts, rooted in leukemic stem-like cells. The oncogenic PML/RARα fusion protein exerts branch-specific regulation in the APL trajectory, including stem-like cells. APL cohort analysis establishes an association of leukemic stemness with elevated white blood cell counts and FLT3-ITD mutations. Furthermore, we construct an APL-specific stemness score, which proves effective in assessing early death risk. Finally, we show that ATRA induces differentiation of primitive blasts and patients with early death exhibit distinct stemness-associated transcriptional programs. Our work provides a thorough survey of APL cellular hierarchies, offering insights into cellular dynamics during targeted therapy.

Epithelial-Mesenchymal Transition in Acute Leukemias

Epithelial-mesenchymal transition (EMT) is a metabolic process that confers phenotypic flexibility to cells and the ability to adapt to new functions. This transition is critical during embryogenesis and is required for the differentiation of many tissues and organs. EMT can also be induced in advanced-stage cancers, leading to further malignant behavior and chemotherapy resistance, resulting in an unfavorable prognosis for patients. Although EMT was long considered and studied only in solid tumors, it has been shown to be involved in the pathogenesis of hematological malignancies, including acute leukemias. Indeed, there is increasing evidence that EMT promotes the progression of acute leukemias, leading to the emergence of a more aggressive phenotype of the disease, and also causes chemotherapy resistance. The current literature suggests that the levels and activities of EMT inducers and markers can be used to predict prognosis, and that targeting EMT in addition to conventional therapies may increase treatment success in acute leukemias.

Stromal area differences with epithelial-mesenchymal transition gene changes in conjunctival and orbital mucosa-associated lymphoid tissue lymphoma

Purpose

To examine the molecular biological differences between conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma and orbital MALT lymphoma in ocular adnexa lymphoma.

Methods

Observational case series. A total of 129 consecutive, randomized cases of ocular adnexa MALT lymphoma diagnosed histopathologically between 2008 and 2020.Total RNA was extracted from formalin-fixed paraffin-embedded tissue from ocular adnexa MALT lymphoma, and RNA-sequencing was performed. Orbital MALT lymphoma gene expression was compared with that of conjunctival MALT lymphoma. Gene set (GS) analysis detecting for gene set cluster was performed in RNA-sequence. Related proteins were further examined by immunohistochemical staining. In addition, artificial segmentation image used to count stromal area in HE images.

Results

GS analysis showed differences in expression in 29 GS types in primary orbital MALT lymphoma (N=5,5, FDR q-value <0.25). The GS with the greatest difference in expression was the GS of epithelial-mesenchymal transition (EMT). Based on this GS change, immunohistochemical staining was added using E-cadherin as an epithelial marker and vimentin as a mesenchymal marker for EMT. There was significant staining of vimentin in orbital lymphoma (P<0.01, N=129) and of E-cadherin in conjunctival lesions (P=0.023, N=129). Vimentin staining correlated with Ann Arbor staging (1 versus >1) independent of age and sex on multivariate analysis (P=0.004). Stroma area in tumor were significant difference(P<0.01).

Conclusion

GS changes including EMT and stromal area in tumor were used to demonstrate the molecular biological differences between conjunctival MALT lymphoma and orbital MALT lymphoma in ocular adnexa lymphomas.

Identification and validation of a prognostic risk-scoring model for AML based on m7G-associated gene clustering

Background

Acute myeloid leukemia (AML) patients still suffer from poor 5-year survival and relapse after remission. A better prognostic assessment tool is urgently needed. New evidence demonstrates that 7-methylguanosine (m7G) methylation modifications play an important role in AML, however, the exact role of m7G-related genes in the prognosis of AML remains unclear.

Methods

The study obtained AML expression profiles and clinical information from TCGA, GEO, and TARGET databases. Using the patient data from the TCGA cohort as the training set. Consensus clustering was performed based on 29 m7G-related genes. Survival analysis was performed by KM curves. The subgroup characteristic gene sets were screened using WGCNA. And tumor immune infiltration correlation analysis was performed by ssGSEA.

Results

The patients were classified into 3 groups based on m7G-related genebased cluster analysis, and the differential genes were screened by differential analysis and WGCNA. After LASSO regression analysis, 6 characteristic genes (including CBR1, CCDC102A, LGALS1, RD3L, SLC29A2, and TWIST1) were screened, and a prognostic risk-score model was constructed. The survival rate of low-risk patients was significantly higher than that of high-risk patients (p < 0.0001). The area under the curve values at 1, 3, and 5 years in the training set were 0.871, 0.874, and 0.951, respectively, indicating that this predictive model has an excellent predictive effect. In addition, after univariate and multivariate Cox regression screening, histograms were constructed with clinical characteristics and prognostic risk score models to better predict individual survival. Further analysis showed that the prognostic risk score model was associated with immune cell infiltration.

Conclusion

These findings suggest that the scoring model and essential risk genes could provide potential prognostic biomarkers for patients with acute myeloid leukemia.

TRIB3, as a robust prognostic biomarker for HNSC, is associated with poor immune infiltration and cancer cell immune evasion

Objective

As a pseudokinase, Tribbles Pseudokinase 3 (TRIB3) is implicated in a wide array of biological processes, including cell signal transduction, metabolic regulation, stress responses, and immune regulation. While its significant role in the immune regulation of certain cancers is well-established, the specific functions and impact of TRIB3 in head and neck squamous cell carcinoma (HNSC) remain unclear.

Methods

The data of RNA-sequence was acquired from the TCGA database to analyze the expression patterns of TRIB3 and elucidate its prognostic value in HNSC patients. Furthermore, the correlation between TRIB3 and tumor mutation burden, clinical data, immune checkpoint genes, and immune cell infiltration was explored. Moreover, the TRIB3 location in tumor tissues and subcellular structures was identified via Tisch in the HPA database, and the potential protein interaction molecules for TRIB3 were elucidated in the STRING database. The potential TRIB3 gene function was assessed using gene set enrichment analysis (GSEA), whereas the TRIB3 expression levels in clinical HNSC samples were verified by RT-qPCR and immunohistochemistry. the role of TRIB3 in enhancing the malignant behavior of HNSC cells was validated in vitro through a series of methods including RT-qPCR, CCK8 assay, wound healing assay, and transwell assay.

Results

It was revealed that TRIB3 was significantly overexpressed in the nucleus and cytoplasm of HNSC. Furthermore, this overexpression markedly enhanced the migration ability of tumor cells. As an independent prognostic factor, TRIB3 was associated with advanced tumor T stage and was significantly involved with tumor mutation burden and immune cell infiltration in HNSC. Moreover, it was observed that TRIB3 was not a predicted factor for PD1/PDL1 and ATL4 inhibitor treatment; however, it was substantially correlated with various immune evasion-related genes in HNSC.

Conclusion

TRIB3 could serve as a potential prognostic marker for HNSC and might be a key gene mediating HNSC immune evasion.

Reciprocal regulation of TWIST1 and OGT determines the decitabine efficacy in MDS/AML

Chemoresistance poses a significant impediment to effective treatment strategies for myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Our previous study unveiled that oncogene TWIST1 interacted with DNA methyltransferase 3a (DNMT3a) to regulate the decitabine (DAC) resistance in MDS/AML. However, the underlying mechanism of TWIST1 dysregulation in DAC resistance remained enigmatic. Here, we found that O-GlcNAc modification was upregulated in CD34+ cells from MDS/AML patients who do not respond to DAC treatment. Functional study revealed that O-GlcNAcylation could stabilize TWIST1 by impeding its interaction with ubiquitin E3 ligase CBLC. In addition, as one typical transcription factor, TWIST1 could bind to the promoter of O-GlcNAc transferase (OGT) gene and activate its transcription. Collectively, we highlighted the crucial role of the O-GlcNAcylated TWIST1 in the chemoresistance capacity of MDS/AML clonal cells, which may pave the way for the development of a new therapeutic strategy targeting O-GlcNAcylated proteins and reducing the ratio of MDS/AML relapse. Video Abstract.

Analysis of endoplasmic reticulum stress-related gene signature for the prognosis and pattern in diffuse large B cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma in adults. This study aimed to determine the prognostic significance of endoplasmic reticulum (ER) stress-related genes in DLBCL. ER stress-related genes were obtained from the molecular signatures database. Gene expression data and clinical outcomes from the gene expression omnibus and TCGA datasets were collected, and differentially expressed genes (DEGs) were screened out. Gene ontology enrichment analysis, the kyoto encyclopaedia of genes and genomes pathway analysis, and geneset enrichment analysis were used to analyse the possible biological function of ER stress-related DEGs in DLBCL. Protein-protein interaction network construction using the STRING online and hub genes were identified by cytoHubba on Cytoscape software. The significant prognosis-related genes were screened, and the differential expression was validated. The immune microenvironment assessment of significant genes were evaluated. Next, the nomogram was built using univariate and multivariate Cox regression analysis. 26 ER stress-related DEGs were screened. Functional enrichment analysis showed them to be involved in the regulation of the endoplasmic reticulum mainly. NUPR1 and TRIB3 were identified as the most significant prognostic-related genes by comparison with the GSE10846, GSE11318, and TCGA datasets. NUPR1 was correlated with a good prognosis and immune infiltration in DLBCL; on the other hand, high expression of TRIB3 significantly correlated with a poor prognosis, which was an independent prognostic factor for DLBCL. In summary, we identified NUPR1 and TRIB3 as critical ER stress-related genes in DLBCL. NUPR1 might be involved in immune infiltration in DLBCL, and TRIB3 might serve as a potential therapeutic target and prognostic factor in DLBCL.

An "unexpected" role for EMT transcription factors in hematological development and malignancy

The epithelial to mesenchymal transition (EMT) is a fundamental developmental process essential for normal embryonic development. It is also important during various pathogenic processes including fibrosis, wound healing and epithelial cancer cell metastasis and invasion. EMT is regulated by a variety of cell signalling pathways, cell-cell interactions and microenvironmental cues, however the key drivers of EMT are transcription factors of the ZEB, TWIST and SNAIL families. Recently, novel and unexpected roles for these EMT transcription factors (EMT-TFs) during normal blood cell development have emerged, which appear to be largely independent of classical EMT processes. Furthermore, EMT-TFs have also begun to be implicated in the development and pathogenesis of malignant hematological diseases such as leukemia and lymphoma, and now present themselves or the pathways they regulate as possible new therapeutic targets within these malignancies. In this review, we discuss the ZEB, TWIST and SNAIL families of EMT-TFs, focusing on what is known about their normal roles during hematopoiesis as well as the emerging and "unexpected" contribution they play during development and progression of blood cancers.

All-Trans Retinoic Acid Promotes a Tumor Suppressive OTUD6B-β-TrCP-SNAIL Axis in Esophageal Squamous Cell Carcinoma and Enhances Immunotherapy

β-TrCP is an E3 ubiquitin ligase that plays important roles in multiple human cancers including esophageal squamous cell carcinoma (ESCC). Analysis of ESCC patient samples reveal that only protein level but not transcript level of β-TrCP associated with patient prognosis, suggesting regulators of β-TrCP protein stability play an essential role in ESCC progression and may be novel targets to develop ESCC therapies. Although β-TrCP stability is known to be mediated by the ubiquitin-proteasome system, it is unclear which enzymes play a major role to determine β-TrCP stability in the context of ESCC. In this study, OTUD6B is identified as a potent deubiquitinase of β-TrCP that suppress ESCC progression through the OTUD6B-β-TrCP-SNAIL axis. Low OTUD6B expression is associated with a poor prognosis of ESCC patients. Importantly, all-trans retinoic acid (ATRA) is found to promote OTUD6B translation and thus suppress ESCC tumor growth and enhance the response of ESCC tumors to anti-PD-1 immunotherapies. These findings demonstrate that OTUD6B is a crucial deubiquitinase of β-TrCP in ESCC and suggest combination of ATRA and anti-PD-1 immune checkpoint inhibitor may benefit a cohort of ESCC patients.

The functions and molecular mechanisms of Tribbles homolog 3 (TRIB3) implicated in the pathophysiology of cancer

Currently, cancer ranks as the second leading cause of death worldwide, and at the same time, the burden of cancer continues to increase. The underlying molecular pathways involved in the initiation and development of cancer are the subject of considerable research worldwide. Further understanding of these pathways may lead to new cancer treatments. Growing data suggest that Tribble's homolog 3 (TRIB3) is essential in oncogenesis in many types of cancer. The mammalian tribbles family's proteins regulate various cellular and physiological functions, such as the cell cycle, stress response, signal transduction, propagation, development, differentiation, immunity, inflammatory processes, and metabolism. To exert their activities, Tribbles proteins must alter key signaling pathways, including the mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K)/AKT pathways. Recent evidence supports that TRIB3 dysregulation has been linked to various diseases, including tumor development and chemoresistance. It has been speculated that TRIB3 may either promote or inhibit the onset and development of cancer. However, it is still unclear how TRIB3 performs this dual function in cancer. In this review, we present and discuss the most recent data on the role of TRIB3 in cancer pathophysiology and chemoresistance. Furthermore, we describe in detail the molecular mechanism TRIB3 regulates in cancer.

All-trans retinoic acid enhances the anti-tumour effects of fimaporfin-based photodynamic therapy

The vitamin A metabolite all-trans retinoic acid (ATRA; tretinoin) has anticancer potential. However, lack of clinical success has prevented its approval for solid tumours. Herein, we propose combining short-term low-dose ATRA with fimaporfin-based photodynamic therapy (ATRA+PDT) for the improved treatment of solid cancers. Compared to monotherapies, ATRA+PDT induced synergistic cytotoxic responses including promotion of apoptosis in colon and breast carcinoma cell lines. Neither enhanced activity of alkaline phosphatase (ALP) nor increased expression of CD133 was detected after ATRA treatment indicating that the improved therapeutic effect of ATRA+PDT is independent of the differentiation state of the cancer cells. In the human colorectal adenocarcinoma cell line HT-29, the effect of ATRA+PDT on gene expression was evaluated by RNA sequencing (RNA-seq). We identified 1129 differentially expressed genes (DEGs) after ATRA+PDT compared to PDT. Ingenuity Pathway Analysis (IPA) predicted the unfolded protein response (UPR), interferon (IFN) signaling and retinoic acid-mediated apoptosis signaling as strongly activated canonical pathways after ATRA+PDT compared to PDT. A validation of the RNA-sec data by RT-qPCR revealed that ATRA+PDT elevated mRNA expression of early growth response 1 (EGR1) and strongly the stress-induced activating transcription factor 3 (ATF3), of which was confirmed on the protein level. In addition, ATRA+PDT abolished mRNA expression of regenerating islet-derived protein 4 (REG4). During the first 20 days post-ATRA+PDT, we obtained significant anti-tumour responses in HT-29 xenografts, including complete responses in 2/5 mice. In conclusion, ATRA+PDT represent a novel combination therapy for solid tumours that should be further tested in immunocompetent preclinical models.

TRIB3 Interacts with STAT3 to Promote Cancer Angiogenesis

OBJECTIVE

Vascular endothelial growth factor A (VEGFA) is a key regulator of angiogenesis, which is a hallmark of cancer that promotes cancer growth and metastasis. It is of great significance to find new intervention targets and related regulatory mechanisms of VEGFA related angiogenesis for the treatment of tumors. This study focuses on the role of tribbles pseudokinase 3 (TRIB3)/signal transducer and activator of transcription 3 (STAT3)/VEGFA signaling axis in colon cancer angiogenesis.

METHODS

This study investigated the expression level of TRIB3 in colon cancer through database analysis and tissue microarray analysis. The effect of TRIB3 on proliferation, migration and tube formation ability of human umbilical vein endothelial cells (HUVECs) was further confirmed by CCK8 assay, scratch-wound assay/migration assay and tube formation assay respectively. The regulatory relationship of TRIB3/VEGFA signaling axis was identified by qPCR and Western blotting, which was further confirmed through animal experiments, and the specific regulatory mechanism was explored by immunoprecipitation (IP) and chromatin immunoprecipitation (ChIP) with colon cancer cell lines.

RESULTS

TRIB3 was increased in colon cancer tissues compared to normal tissues, and elevated TRIB3 expression indicated a poor prognosis in colon cancer patients. Moreover, it was found that silencing TRIB3 could inhibit cancer angiogenesis, whereas overexpressing TRIB3 promoted cancer angiogenesis in vitro and in vivo. Mechanistically, TRIB3 physically interacted with STAT3 and enhanced STAT3-mediated transcriptional activity. Furthermore, the function of TRIB3 in cancer angiogenesis was through cooperating with STAT3 to increase the VEGFA expression.

CONCLUSION

Our study provides insights into cancer angiogenesis and offers a potential therapeutic strategy for TRIB3-overexpressed cancer.

TRAF6 Suppresses the Development of Pulmonary Fibrosis by Attenuating the Activation of Fibroblasts

Pulmonary fibrosis (PF) has a high mortality rate, and its pathogenesis is unknown. TNF receptor-associated factor 6 (TRAF6), a signal transducer for inflammatory signaling, plays crucial roles in the pathogenesis of immune diseases. However, its function in PF remains unknown. Herein, we demonstrated that lungs from mice with bleomycin (BLM)-induced PF were characterized by decreased expression of TRAF6 in lung fibroblasts. Enhancing TRAF6 expression protected mice from BLM-induced PF coupled with a significant reduction in fibroblast differentiation. Furthermore, we demonstrated that overexpression of TRAF6 reversed the activation of myofibroblasts from PF mice by reducing the expression of Wnt3a and subsequently suppressing Wnt/β-catenin signaling. Additionally, the abundance of Tribbles pseudokinase 3 (TRIB3), a stress sensor, was negatively correlated with the abundance of TRAF6 in lung fibroblasts. TRIB3 overexpression decreased TRAF6 abundance by reducing TRAF6 stability in lung fibroblasts during PF. Mechanistic studies revealed that TRIB3 bound to TRAF6 and accelerated basal TRAF6 ubiquitination and degradation. Collectively, our data indicate that reduced TRAF6 expression in fibroblasts is essential for the progression of PF, and therefore, genetically increasing TRAF6 expression or disrupting the TRIB3-TRAF6 interaction could be potential therapeutic strategies for fibroproliferative lung diseases in clinical settings.

RBCK1-TRIB3 decelerated the progression of acute promyelocytic leukemia

Under the differentiation induction therapy with all-trans retinoic acid and arsenic trioxide, nearly 95% of typical acute promyelocyte leukemia (APL), which is characterized by the presence of PML-RARA, patients can be cured. Though its good prognosis, if left untreated, the natural survival duration of typical APL patients is only 1 month, but some exceptional cases also exist. Occasionally, we have observed the entire natural clinical course of one extremely indolent APL patient, who developed from pre-APL stage (<20% promyelocytes in bone marrow) to overt-APL stage (≥20% promyelocytes in bone marrow) with one nearly 2-year latency. Strikingly, we identified one novel fusion RBCK1-TRIB3 in the pre-APL stage but not overt-APL stage sample. It has been reported that TRIB3 stabilized PML-RARA to driver APL progression, while RBCK1-TRIB3 partially disrupted TRIB3^WT expression, so it contributed to the deceleration of APL progression in this patient.

AKR1C1 Contributes to Cervical Cancer Progression via Regulating TWIST1 Expression

Cervical cancer (CC) is a common gynecological malignancy, accounting for 10% of all gynecological cancers. Recently, targeted therapy for CC has shown unprecedented advantages. To improve CC patients' prognosis, there are still urgent needs to develop more promising therapeutic targets. Aldo-keto reductase 1 family member C1 (AKR1C1) is a type of aldosterone reductase and plays a regulatory role in a variety of key metabolic pathways. Several studies indicated that AKR1C1 was highly expressed in a series of tumors, and participated in the progression of these tumors. However, the possible effects of AKR1C1 on CC progression remain unclear. Herein, we revealed AKR1C1 was highly expressed in human CC tissues and correlated with the clinical characteristics of patients with CC. AKR1C1 could regulate the proliferation and invasion of cervical cancer cells in vitro. Further experiments showed that AKR1C1 could regulate TWIST1 expression and AKT pathway. In summary, we confirmed the involvement of AKR1C1 in CC progression, and therefore AKR1C1 may have the potential to be a molecular target for CC treatment.

TRIB3 destabilizes tumor suppressor PPARα expression through ubiquitin-mediated proteasome degradation in acute myeloid leukemia

AIMS

Tribbles homolog 3 (TRIB3) is emerging as a multifunctional oncoprotein associated with various cellular events in different tumors. However, the regulatory mechanism of TRIB3 in acute myeloid leukemia (AML) remains unknown. This study aims to investigate the molecular mechanisms and uncover the functions of TRIB3 in AML.

METHODS

Western blotting and quantitative real-time PCR were used to analyze the expression levels of TRIB3, peroxisome proliferator-activated receptor α (PPARα), apoptosis markers and autophagy markers in AML cells. Flow cytometry was used to assess cell apoptosis. The interaction of TRIB3 and PPARα was evaluated by immunofluorescence, coimmunoprecipitation, and in vivo ubiquitination assays.

KEY FINDINGS

We demonstrated that downregulating TRIB3 in leukemic cells effectively induced apoptosis and autophagy by regulating the degradation of PPARα. Mechanistically, TRIB3 interacted with PPARα and contributed to its destabilization by promoting its ubiquitination. When PPARα was activated by its specific agonist clofibrate, the apoptosis and autophagy of AML cells were significantly enhanced. These results were confirmed by rescue experiments. Blocking PPARα expression using the PPARα inhibitor GW6471 reversed the functional influence of TRIB3 on AML cells.

SIGNIFICANCE

The aim of this study is to provide evidence of the degradation of PPARα by TRIB3 via ubiquitin-dependent proteasomal degradation. This process meditates the progression of AML and prolongs the survival of leukemic cells. As a result, these data indicate that TRIB3 is a novel and promising therapeutic target for AML treatment.

Twist of Fate for Acute Promyelocytic Leukemia: TRIB3-TWIST1 Interaction Promotes Resistance

While acute promyelocytic leukemia has a good prognosis with all-trans retinoic acid (ATRA) treatment, ATRA resistance is a major obstacle. It is now demonstrated that TRIBBLES 3 (TRIB3) stabilizes TWIST1, leading to ATRA resistance. Peptides that disrupt this interaction lead to the degradation of TWIST1 and overcome ATRA resistance.See related article by Lin et al., p. 6228.