c-Jun Activation Domain-binding Protein-1 Research Articles

Screen natural terpenoids to identify potential Jab1 inhibitors for treating breast cancer

Jab1 (c-Jun activation domain-binding protein-1) overexpression has been extensively linked to cancer development (or metastasis) in various malignancies by positively regulating cancer cell proliferation or inactivating several tumor suppressors. Recent research has focused on utilizing plant products to target crucial elements of dysregulated signaling pathways to elucidate a potent cancer therapeutic approach. Terpenoids have shown significant anti-inflammatory and anti-cancerous properties in a broader range of carcinomas by inducing apoptosis. Through an extensive literature search, we have selected only those terpenoids (from the NPACT database) that have not been explored against Jab1 (CSN5, COP9 signalosome subunit 5) in breast cancer for our research study. We have used two docking servers, PATCH DOCK, and CB DOCK, to find the binding interaction between selected terpenoids and Jab1. Further, we have also used SWISS ADME to investigate the pharmacokinetics of selected ligands. Amongst all selected ligands, lutein (belongs to the xanthophylls class) has displayed maximum binding energy in both CB Dock and Patch Dock analysis. Hence, our preliminary in silico results have shown lutein as the potent lead candidate for developing a better drug against breast cancer. However, more in silico and in vitro studies are still needed to validate the inhibitory potential of lutein terpenoid against Jab1 in breast cancer.

Reactive Oxygen Species-Mediated c-Jun Activation Domain-Binding Protein-1 (Jab1) Promotes Immune Escape in Hyperleukocytic Acute Myeloid Leukemia

Background: Hyperleukocytic acute myeloid leukemia (HL-AML) is a group of clonal hematopoietic stem cell diseases. Our previous studies have confirmed that Jab1 mediated by reactive oxygen species (ROS) plays a role in the pathogenesis of AML as a transcription coactivator of AP-1/JUN. Here, we reveal the specific regulatory mechanism of immune escape in HL-AML by Jab1, which serves as a new therapeutic target for HL-AML. Methods: The relationship between Jab1 expression and immune cell subtypes in clinical bone marrow samples were analyzed by RT-qPCR. Lentiviral knockout of Jab1 was combined with transcriptomics and chromatin co-precipitation to evaluate the transcriptional regulatory mechanisms involved, and bioinformatics to identify molecular interactions. The changes of each immunophenotype were analyzed by flow cytometry. Results: Compared with healthy controls and AML, Jab1 was highly expressed in HL-AML and was associated with a poor prognosis. However, in HL-AML patients, the proportion of CD8+ T cells was significantly decreased, while the proportion of regulatory T cells was slightly increased, and the secretion of cytokines IL-2, IL-4, IFN-γ, and IFN-α decreased. In H2O2-induced oxidative stress, ROS levels promote the entry of c-Jun into the nucleus, while Jab1 knockdown blocks c-Jun nuclear expression and transcriptional activity. Mechanically, Jab1 regulates leukemic immunosuppressive target LILRB4 rather than PDL1/PDL2. As a coactivator of transcription factor c-Jun, Jab1 cannot directly regulate the transcription of LILRB4 but enhances the stability of LILRB4 mRNA. By high-throughput screening, it was found that N6-methyladenosine modification directly recognized the LILRB4 mRNA site. Finally, it was concluded that Jab1/IGF2BPs/LILRB4 signal axis was involved in disease progression in HL-AML. Conclusions: We provided compelling evidence to demonstrate that Jab1 under oxidative stress is associated with tumorigenesis and poor prognosis of AML, which can serve as a target to develop therapeutics for cancer treatment.

PB2171: THE NOVEL CSN5/JAB1 INHIBITOR CSN5I-3 SUPPRESSES CELL GROWTH AND UPREGULATES GENE EXPRESSION OF TYPE-I INTERFERONS (IFN) IN ANAPLASTIC LARGE CELL LYMPHOMA (ALCL)

Background: The CSN5/Jab1 (cJun activation domain-binding protein 1), initially discovered as a cJun coactivator, represents the fifth component of an evolutionary highly conserved 8 subunit protein complex, named COP9 signalosome (CSN5). Accumulating evidence suggests that the CSN5/Jab1 gene operates as an oncogene in cancer through multiple mechanisms including cell cycle control via CDK inhibitors. We have previously shown that CSN5/Jab1 protein is overexpressed in T-cell lymphomas with the highest frequency of positive tumors being observed in both ALK+ and ALK- anaplastic large cell lymphomas (ALCL). Targeting CSN5/Jab1 activity in cancer is now possible since a novel inhibitor, namely CSN5i-3 (Novartis), has been developed for clinical use. The potential role of CSN5/Jab1 in modulation of anti-tumor immune responses in cancer, and particularly in ALCL, is unknown to date. Aims: To investigate the effects of the selective CSN5i-3 inhibitor in cell growth and type-I interferon - associated anti-tumor immune responses in ALCL. Methods: The ALCL in vitro system included 5 cell lines (3 ALK+ and 2 ALK- ALCL cell lines). Cell growth and viability were assessed by trypan blue and MTT assays. The effects of the CSN5i-3 on G1-S cell cycle progression were assessed by BrdU incorporation assay and on apoptosis by Annexin V/AAD staining and flow cytometry. Expression of various cell cycle regulating proteins at baseline and experimental conditions were analysed by Westem blot analysis. Gene expression of type I interferons, including interferonbeta (IFN-β), CXCL10 and interferon gamma (IFN-y), as well as, STING and a control gene (GAPDH) at the RNA level, were analysed with qRT-PCR. The ALCL cell lines were treated with the specific CSN5i-3 inhibitor at different concentrations. Silencing of the CSN5/Jab1 gene was performed using transient transfection with specific siRNA construct using the Amaxa Nucleofector System (Lonza). Results: Treatment of ALCL cell lines with increasing concentrations of CSN5i-3 resulted in decreased protein levels of CSN5/Jab1, which was associated with significantly decreased cell growth but slight increase in apoptosis (10-15%). The effects on cell growth linked to downregulation of cell cycle progression were associated with upregulation of the CDK inhibitors p21, p27 and p57. Similarly, CSN5/Jab1 gene silencing resulted in decreased cell growth associated with increased expression of similar cell cycle inhibiting proteins. In addition, inhibition of CSN5/Jab1 activity by CSN5i-3 resulted in increased IFN-β and IFN-y mRNA levels in ALK+ ALCL cells, and CXCL10, IFN-y and STING mRNA levels in ALK- ALCL cells. Similarly, knocking down CSN5/Jab1 gene by transient transfection with siRNA led to upregulation of type-I interferons, particularly IFN-β and CXCL10 in ALCL, suggesting that the effects of CSN5i-3 can be attributed to specific inhibition of CSN5/Jab1 activity. Summary/Conclusion: The novel inhibitor CSN5i-3 sufficiently downregulates expression of CSN5/Jab1 oncogene, inhibits cell cycle progression and contributes to type-I interferon - associated anti-tumor immune response in ALK+ and ALK- ALCL. These preclinical findings suggest a potential role of CSN5i-3 in molecular therapeutics and immunotherapy in T-cell lymphomas.

Evaluation of Phytocompounds of Vitis vinifera, Tabernaemontana corymbosa and Aloe vera against JAB1: A Strategy to Treat Cervical Cancer

JAB1 or C-Jun activation domain-binding protein-1 plays a role in controlling cellular proliferation, cell apoptosis, cell cycle, and regulating genomic instability as well as DNA damage response. JAB1 dysregulation contributes to oncogenesis via deactivating tumor suppressor genes. Vitis vinifera, Tabernaemontana corymbosa, and Aloe vera have been known for their antitumor functions. However, the inhibitory role of phytocompounds derived from Vitis vinifera, Tabernaemontana corymbosa, and Aloe barbadensis miller (Aloe vera) against JAB1 has not yet been elucidated. Therefore, we studied the naturally derived compounds from Vitis vinifera, Tabernaemontana corymbosa, and Aloe vera, which can interact and decrease the activities of JAB1 using in-silico analysis. Eighty-one compounds were screened using PyRx and further analyzed via Lipinski's rule. Further, on executing molecular docking studies on the sixty selected compounds, Iboluteine was found to be a potent inhibitor of JAB1 and should further be explored in in-vitro studies to substantiate these assertions. Phytocompounds are a reservoir of bioactive molecules that can be particularly useful in treating cervical cancer due to their limited toxicity and amenability from the development of drug resistance. Thus, this study aims to identify possible naturally derived compounds from Vitis vinifera, Tabernaemontana corymbosa, and Aloe vera, which can selectively decrease the activities of JAB1 that has the potential to be a crucial anti-cancer therapeutic molecule against cervical cancer.

Jab1 (COPS5) as an Emerging Prognostic, Diagnostic and Therapeutic Biomarker for Human Cancer

Jab1 (C-Jun activation domain-binding protein-1) has been reported to be critically involved in regulating apoptosis, cell proliferation, cell cycle, thereby affecting numerous pathways, DDR (DNA damage response) regulation, and genomic instability. Jab1 (CSN5) dysregulation has been positively associated with oncogenesis via activating oncogenes and deactivating various tumor suppressors. Jab1 overexpression has been reported in several tumor forms, illuminating its potent efficacy in cancer progression and metastasis. Jab1 has instigated prompt research interest in elucidating inhibitors of numerous oncoproteins and oncogenes for chemotherapeutics. Our review has presented strong evidence for presenting the significance of Jab1 overexpression in numerous carcinomas and its involvement in modulating various signaling pathways for cancer cell survival. This review may project a new way for utilizing Jab1 as a strong target for developing potent inhibitory compounds targeting Jab1 that could be further utilized in chemoprevention with limited side effects. Altogether this review further confirmed the crucial involvement of Jab1 in carcinogenesis and tumorigenesis, displaying the strong potential of Jab1 as one of the potent cancer biomarkers.

Jab1/Cops5: a promising target for cancer diagnosis and therapy.

C-Jun activation domain-binding protein1 (Jab1), the fifth component of the constitutive photomorphogenic-9 signalosome (COPS5/Csn5) complex, functions in several cellular processes to affect different signaling pathways. Dysregulation of Jab1/Csn5 both restrains tumor suppressors and activates oncogenes to contribute oncogenesis. Jab1 overexpressed in various tumorsand played an essential part in cancer initiation, progression and prognosis, which has spurred strong research interest in developing inhibitors for cancer therapy. Here, we summarize the multiple signaling pathways and functions of Jab1/Csn5 in tumorigenesis. By querying the Oncomine database, a cancer microarray database and web-based data-mining platform aimed at facilitating discovery from genome-wide expression analyses, we investigated statistically the differential expression of Jab1/Csn5 between different cancer samples and the corresponding normal tissue samples, cancer samples with different histological types, different cancer types, and different clinical outcomes. These statistical data confirmed the significant role of Jab1/Csn5 in carcinogenesis, indicating Jab1/Csn5 as a biomarker and a therapeutic target in different cancers.

Prognostic role of c‐Jun activation domain‐binding protein‐1 in cancer: A systematic review and meta‐analysis

c‐Jun activation domain‐binding protein‐1 (Jab1) is aberrantly overexpressed in multiple cancers and plays an oncogenic role in cancer progression. We examined the association between Jab1 expression and prognosis in patients with cancer by conducting a meta‐analysis. A comprehensive search strategy was performed using the PubMed, Web of Science, Ovid and EMBASE in July 2020. Eligible studies were enrolled according to definite criteria. Twenty‐seven studies involving 2609 patients were enrolled in this meta‐analysis. A significant association between high Jab1 expression and poor overall survival (pooled hazard ratio [HR] 2.344, 95% confidence interval [CI]: 2.037‐2.696) was observed. Subgroup analyses of the type of cancer, sample size, follow‐up period, Jab1 detection method and preoperative treatment did not alter the significance. On pooling data from Cox multivariate analyses, high Jab1 expression was found to be an independent prognostic indicator for overall survival. In addition, high Jab1 expression was found to be associated with advanced clinicopathological features such as clinical stage, lymphatic metastasis, histological grade and distant metastasis in cancers. Our meta‐analysis is the first to demonstrate that high Jab1 expression may be a promising indicator of poor prognosis and has an independent prognostic value for overall survival in patients with cancer.

NT157 Inhibits HCC Migration via Downregulating the STAT3/Jab1 Signaling Pathway.

Purpose:The high fatality-to-case ratio of hepatocellular carcinoma is directly related to metastasis. The signal transducer and activator of transcription-3 is a key mediator of the cytokine and growth factor signaling pathways and drives the transcription of genes responsible for cancer-associated phenotypes. However, so far, no specific inhibitor for signal transducer and activator of transcription-3 has been used in clinical practice. Therefore, targeting the signal transducer and activator of transcription-3 for cancer therapy is highly desired to improve outcomes in patients with hepatocellular carcinoma.Experimental Design:Using the small-molecule inhibitor NT157, the effect of signal transducer and activator of transcription-3 inhibition on cell migration was tested in hepatocellular carcinoma cell lines and a lung metastasis model of the disease.Results:NT157 significantly inhibited the migration of hepatocellular carcinoma cell lines in vitro and lung metastasis of hepatocellular carcinoma in vivo. Mechanistically, it inhibited the phospho-signal transducer and activator of transcription-3 in a dose- and time-dependent manner. Furthermore, NT157 treatment suppressed the c-Jun activation domain-binding protein-1 levels in the nucleus but no significant decrease was observed in its expression in the cytoplasm. Finally, high mRNA expression levels of signal transducer and activator of transcription-3 and c-Jun activation domain-binding protein-1 in hepatocellular carcinoma were associated with significantly low survival rates.Conclusion:NT157 inhibits hepatocellular carcinoma migration and metastasis by downregulating the signal transducer and activator of transcription-3/c-Jun activation domain-binding protein-1 signaling pathway and targeting it may serve as a novel therapeutic strategy for the clinical management of hepatocellular carcinoma in the future.

JAB1 Promotes High Glucose-Induced Inflammation and Extracellular Matrix Deposition in Glomerular Mesangial Cells by Regulating Angiopoietin-Like Protein 2

Diabetic or hyperglycaemic conditions stimulate the inflammatory response, excessive accumulation of extracellular matrix, and result in glomerulosclerosis, a scarring process of diabetic nephropathy. c-Jun activation domain-binding protein 1 (JAB1) functions as a regulator of pathways involved in cellular apoptosis and proliferation. The role of JAB1 in diabetic nephropathy was investigated in this study. Firstly, glomerular mesangial cells (GMCs) were treated with high glucose, and high glucose conditions induced up-regulation of JAB1 in the GMCs. Moreover, IL-6, TNF-α, MCP-1, and IL-1β were also elevated in high glucose-induced GMCs. Secondly, silencing of JAB1 reduced the levels of IL-6, TNF-α, MCP-1, and IL-1β in high glucose-induced GMCs. In addition, silencing of JAB1 attenuated the high glucose-induced decrease of superoxide dismutase (SOD) and the increase of reactive oxygen species (ROS) and malondialdehyde (MDA). The increased TGF-β1, collagen I, collagen IV, and fibronectin levels in high glucose-induced GMCs were restored by knockdown of JAB1. Thirdly, angiopoietin-like protein 2 (ANGPTL2) expression was reduced by JAB1. Over-expression of ANGPTL2 weakened the JAB1 silence-induced decrease of IL-6, TNF-α, MCP-1, IL-1β, TGF-β1, collagen I, collagen IV, and fibronectin. In conclusion, silencing of JAB1 reduced extracellular matrix deposition and suppressed inflammation in high glucose-induced GMCs through down-regulation of ANGPTL2.

JAB1 promotes palmitate-induced insulin resistance via ERK pathway in hepatocytes.

Insulin resistance (IR) is the primary pathological mechanism underlying Type 2 diabetes mellitus (T2DM). Many researches have reported the relationship between chronic inflammation and IR, while the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway is rapidly activated in inflammatory conditions. However, the functional role of ERK1/2 in IR remains to be identified. We here reported that C-Jun activation domain-binding protein-1 (JAB1) was upregulated in IR. In addition, we showed that depletion of JAB1 led to recovery of insulin sensitivity. Given the fact that JAB1 played as an activator of ERK1/2, we assumed JAB1 was involved in IR through ERK pathway. So we assessed the effects of JAB1 knockdown in palmitate acid (PA) treated HepG2 cells. Importantly, JAB1 siRNA blocked the effect of PA-induced activation of ERK1/2. Furthermore, silencing of JAB1 could reduce the release of inflammatory factors, facilitate hepatic glucose uptake and improve lipid metabolism. All these data implicated that JAB1 knockdown might alleviate PA-induced IR through ERK pathway in hepatocytes.

Abstract 586: Anti-leukemia activities of selenium nanoparticles embedded in nanotube consisted of triple-helix β-D-glucan

Abstract Background: Acute myeloid leukemia (AML) is a hematological malignant tumor. The common chemotherapy results in various side-effect and drug-resistance for AML, so it is urgent to find a non-toxic natural drug for AML therapy. Herein, for the first time, the Se nanoparticles embedded in nanotube consisted of triple helix β-D-glucan (BFP) exhibit the high anti-leukemia effects. Methods: A triple helix β-(1, 3)-D-glucan (BFP) extracted from the black fungus was self-assembled into nanotube in water, and Se nanoparticles (SeNPs) were wrapped to form stable inclusion complex BFP-Se. The CCK8 assays, lactose dehydrogenase release assays, optofluidics chips and flow cytometry were used to test the anti-leukemia effects of BFP-Se in vitro and in vivo. Results: The SeNPs embedded in the BFP nanotubes exhibited high stability in water, avoiding aggregation and dispersion to out. In vitro, the BFP-Se significantly inhibited the proliferation of AML cell lines and patient cells and markedly increased the cytotoxicity on AML cells. BFP-Se slowed the Molm-13 GFP+ cells growth. On single-cell levels, the U937 cells were gradually swelled and lysed with BFP-Se treatment. In addition, BFP-Se had little toxic to hematopoietic stem cells (HSC) and T cells compared to Ara-c. Flow cytometry indicated that BFP-Se promoted the cell apoptosis and blocked cell cycle of AML cells. Further, after injection of BFP-Se, the survival was longer on AML PDX model constructed with B-NSG mice. The blood and bone marrow analysis indicated the anti-leukemia effects of BFP-Se in vivo. Moreover, BFP-Se extremely increased the total antioxidant capacity (T-AOC) of AML cells, and decreased the expression of c-Jun activation domain-binding protein-1 (Jab1) and thioredoxin 1 (Trx1). Conclusion: This biocompatible polysaccharide nanotube containing Se nanoparticles - against AML would provide a novel strategy for AML therapy. Citation Format: Yanxia Jin, Liqin Cai, Qian Yang, Ziyi Luo, Lina Zhang, Fuling Zhou. Anti-leukemia activities of selenium nanoparticles embedded in nanotube consisted of triple-helix β-D-glucan [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 586.

The Antioxidant Enzyme Methionine Sulfoxide Reductase A (MsrA) Interacts with Jab1/CSN5 and Regulates Its Function.

Methionine sulfoxide (MetO) is an oxidative posttranslational modification that primarily occurs under oxidative stress conditions, leading to alteration of protein structure and function. This modification is regulated by MetO reduction through the evolutionarily conserved methionine sulfoxide reductase (Msr) system. The Msr type A enzyme (MsrA) plays an important role as a cellular antioxidant and promotes cell survival. The ubiquitin- (Ub) like neddylation pathway, which is controlled by the c-Jun activation domain-binding protein-1 (Jab1), also affects cell survival. Jab1 negatively regulates expression of the cell cycle inhibitor cyclin-dependent kinase inhibitor 1B (P27) through binding and targeting P27 for ubiquitination and degradation. Here we report the finding that MsrA interacts with Jab1 and enhances Jab1′s deneddylase activity (removal of Nedd8). In turn, an increase is observed in the level of deneddylated Cullin-1 (Cul-1, a component of E3 Ub ligase complexes). Furthermore, the action of MsrA increases the binding affinity of Jab1 to P27, while MsrA ablation causes a dramatic increase in P27 expression. Thus, an interaction between MsrA and Jab1 is proposed to have a positive effect on the function of Jab1 and to serve as a means to regulate cellular resistance to oxidative stress and to enhance cell survival.

Anti-leukemia activities of selenium nanoparticles embedded in nanotube consisted of triple-helix β-d-glucan

Acute myeloid leukemia (AML) is a difficult therapeutic hematological tumor. It is urgent to find a non-toxic natural drug to treat AML. Herein, the selenium nanoparticles (SeNPs) embedded in nanotubes consisted of triple helix β-(1, 3)-d-glucan (BFP) from the black fungus that were wrapped to form stable inclusion complex BFP-Se, which was self-assembled and exhibited high stability in water. In vitro, the BFP-Se significantly inhibited the proliferation of AML cells and increased the cytotoxicity on AML cells. On single-cell levels, the U937 cells were gradually swelled and lysed with BFP-Se treatment on optofluidics chips. Further, the blood and bone marrow analysis indicated the anti-leukemia effects of BFP-Se in vivo. Moreover, BFP-Se increased the total antioxidant capacity of AML cells and decreased the expression of c-Jun activation domain-binding protein 1 and thioredoxin 1. Our results suggest that this biocompatible polysaccharide nanotube containing Se nanoparticles would provide a novel strategy for AML therapy.

NPM-ALK Upregulates Jab1/Csn5 through STAT3 Activation in Anaplastic Large Cell Lymphoma: A Novel Function of NPM-ALK That Contributes to PD1/PD-L1 Immune Checkpoint Regulation

Introduction: ALK+ anaplastic large cell lymphoma (ALCL) frequently carries the t(2;5) resulting in overexpression of NPM-ALK oncoprotein, which activates many oncogenic pathways. The Jab1 (c-Jun activation domain-binding protein-1), initially discovered as a c-Jun co-activator, represents the fifth component of an evolutionary highly conserved 8-subunit protein complex, named COP9 signalosome (CSN). The Jab1/Csn5 gene operates as an oncogene in cancer through multiple mechanisms including cell cycle control via the CDK inhibitor p27. Recent evidence suggests that Jab1/Csn5 is also involved in immune checkpoint regulation through PD-L1 stabilization by inhibition of PD-L1 proteasomal degradation. Recently, we reported that the protein levels of Jab1/Csn5 are the highest in ALCL as compared to other peripheral T-cell lymphomas (PTCL) and significantly correlate with PD-L1 levels in PTCLs (Drakos et al, HemaSphere 2019; (3):p596, EHA abstract). In this study, we hypothesized that NPM-ALK may regulate Jab1/Csn5 expression and thus contributes to cell proliferation as well as PD-L1/PD1 immune checkpoint regulation. Methods: The in vitro system included 4 ALK+ (Karpas 299, DEL, SUPM2, SUDHL1) and 2 ALK- (Mac1, Mac2a) ALCL cell lines as well as murine Ba/F3 parental and Ba/F3 clones stably transfected with NPM-ALK (Ba/F3-NPM-ALK), EEF1G (Ba/F3-EEF1G-ALK) or control plasmid (Ba/F3-MIG). Transient transfections with Jab1/CSN si-RNAs and STAT3 si-RNAs were also performed in ALCL cells. In addition, ALCL cells were treated with ALK (Crizotonib) or STAT3 (XIII) inhibitors. Two animal models were used in the study: 1) in the ex vivo model, Karpas-299 clones stably transfected with Jab1/CSN5 shRNA constructs were generated and injected in both thighs of SCID-beige immunocompromised mice. The Jab1/CSN5 shRNA and the control mice were followed for tumor development and their tumors were measured and analysed by immunohistochemistry. 2) in the patient derived xenograft (PDX) model of ALK+ ALCL, the mice were treated with the ALK inhibitor Ceritinib or control vehicle and were monitored for changes in tumor characteristics over two weeks. Tumor specimens were taken at early time points (24, 48, and 72 hrs) following treatment in order to obtain viable tumor cells for protein analysis. Results: Jab1/Csn5 was substantially upregulated in the Ba/F3-NPM-ALK and Ba/F3-EEF1G-ALK stable clones as compared to paternal or control Ba/F3-MIG clones. Jab1/Csn5 upregulation was associated with high STAT3 activation (Tyr705-phosphorylation) and increased PD-L1 gene expression in this system. Inversely, inhibition of ALK activity was associated with STAT3 de-activation and decreased protein levels of Jab1/Csn5 and PD-L1 in ALK+ ALCL cells. Knocking down STAT3 by siRNA or inhibition of its activity by the XIII inhibitor resulted in decreased levels of Jab1/Csn5 protein in both ALK+ and ALK- ALCL cell lines. The SCID-beige mice that received Jab1/CSN5-shRNA clones showed significant delay in tumor development and longer survival as compared to control mice, which was associated with significantly decreased PD-L1 protein levels and p27 upregulation in the tumor cells (xenografts). Treatment of the PDX mice with Ceritinib, a potent next generation ALK inhibitor, resulted in substantial tumor necrosis after 72 hrs and decreased tumor size at day 7 post-treatment. At earlier time points, de-activation (de-phosphorylation) of ALK kinase and STAT3 was observed in the Ceritinib-treated mice, which was linked to variably lower levels of Jab1/CSN5 and PD-L1 proteins as compared to control mice. Conclusion: Jab1/CSN5 is a novel downstream target of the NPM-ALK oncogenic kinase that regulates its expression, at least in part, through STAT3 activation. The Jab1/CSN5-mediated stabilization of PD-L1 can be efficiently inhibited by Ceritinib in preclinical animal models of ALK+ ALCL. Disclosures Österborg: BeiGene: Research Funding; Janssen: Research Funding; Abbvie: Research Funding; Kancera AB: Research Funding; Gilead: Research Funding. Vega:National Cancer Institute, national Institutes of Health: Other: Grant Funding-R01CA222918.

JAB1/COPS5 is a putative oncogene that controls critical oncoproteins deregulated in prostate cancer

Recent evidence support that the c-Jun activation domain-binding protein 1 (JAB1)/COPS5 has an oncogenic function in various tissues. We show that JAB1 amplification in human prostate cancer (PCa) correlates with reduced overall survival and disease-free progression. Immunohistochemical staining shows enhanced expression of JAB1 in the cytoplasmic compartment of PCa cells compared to the normal prostate epithelium, indicating the activity/function of JAB1 is altered in PCa. To test the function of JAB1 in PCa, we efficiently silenced JAB1 expression using four unique shRNAs in three PCa cell lines (LNCaP, C4-2, and PC-3) and an immortalized prostate epithelial cell line, RWPE-1. Our data clearly show that silencing JAB1 robustly suppresses the growth of PCa cells, but not RWPE-1 cells, suggesting that PCa cells become addicted to JAB1. To study the potential mechanism by which JAB1 controls PCa growth, we profiled gene expression changes by whole transcriptome microarray analysis of C4-2 cells silenced for JAB1 using a pool of 3 shRNAs compared to scrambled shRNA control. We identified 1268 gene changes ≥1.5 fold by silencing JAB1 in C4-2. Western blot confirmation and bioinformatics pathway analyses support that PCa cells become addicted to JAB1 through controlling the following signaling pathways: cell cycle, p53 signaling, DNA replication, TGF-β/BMP, MAPK, TNF, and steroid hormone biosynthesis. We propose that UGT2B28, UGT2B10, UGT2B11, Skp2, EZH2, MDM2, BIRC5 (Survivin), UBE2C, and Smads 1/5/8, which are all associated with the abovementioned key oncogenic pathways, may play critical roles in the putative oncogenic function of JAB1 in PCa.

An in silico study on plant-derived inhibitors against a prognostic Biomarker, Jab1

Cancer kills millions of people worldwide every year. The main form of treatment at this point is chemotherapy, which comprises of systemic drug delivery so that they can kill the cancerous cells more effectively. But most of these drugs cause severe side effects in patients and, therefore there is a strong need to focus on identifying natural compounds as a potent phytoinhibitors using various in silico and in vitro approaches. Natural compounds pose low toxicity, hence render them to be an excellent alternative to the basis for the development of new anti-cancerous drugs. Our study considers an effective therapeutic target, Jab1 (c-Jun activation domain-binding protein-1) or a c-Jun coactivator, which has been implicated in multiple protein interactions that play a significant role in various stages of carcinogenesis. Hence we have performed screening of 1500 natural compounds having anticancerous activity by applying various in silico approaches including Lipinski rule of five, ADME, and various Molecular Docking tools. In this study, we have identified two potent phytoinhibitors against Jab1 which needs to be further validated through in vitro approaches.

A nonsense mutant of the hepatitis B virus large S protein antagonizes multiple tumor suppressor pathways through c-Jun activation domain-binding protein1.

Hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC). Previous studies have identified recurrent nonsense mutations in the HBV large S (LHBs) gene from the liver from HBV core antigen-positive HCC patients. These nonsense mutants have been shown to be oncogenic in mouse xenograft models using a mouse embryonic fibroblast cell line. Here, we expressed in a liver cell line Huh-7 a carboxy terminally truncated protein from a nonsense mutant of the LHBs gene, sW182* (stop codon at tryptophane-182). Although the sW182* protein appeared not to be very stable in the cultured liver cells, we confirmed that the protein can be highly expressed and retained for a prolonged period of time in the hepatocytes in the mouse liver, indicating its stable nature in the physiological condition. In the Huh-7 cells, the sW182* mutant downregulated tumor suppressors p53 and Smad4. This downregulation was reversed by a proteasome inhibitor MG132, implying the involvement of proteasome-based protein degradation in the observed regulation of the tumor suppressors. On the other hand, we found that c-Jun activation domain-binding protein 1 (Jab1) physically interacts with the sW182*, but not wild-type LHBs. RNA interference (RNAi) of Jab1 restored the levels of the downregulated p53 and Smad4. The sW182* mutant inhibited the promoter activity of downstream target genes of the tumor suppressors. Consistently, Jab1 RNAi reversed the inhibition. These results suggest that the LHBs nonsense mutant antagonizes the tumor suppressor pathways through Jab1 in the liver contributing to HCC development.

Jab1/COPS5 as a Novel Biomarker for Diagnosis, Prognosis, Therapy Prediction and Therapeutic Tools for Human Cancer

C-Jun activation domain-binding protein-1 (Jab1) involves in controlling cellular proliferation, cell cycle, apoptosis, affecting a series of pathways, as well as regulating genomic instability and DNA damage response (DDR). Jab1/COPS5 dysregulation contributes to oncogenesis by deactivating several tumor suppressors and activating oncogenes. Jab1 overexpression was found in many tumor types, illuminating its important role in cancer initiation, progression, and prognosis. Jab1/COPS5 has spurred a strong research interest in developing inhibitors of oncogenes/oncoproteins for cancer therapy. In this paper, we present evidences demonstrating the importance of Jab1/COPS5 overexpression in several cancer types and recent advances in dissecting the Jab1/COPS5 upstream and downstream signaling pathways. By conducting ingenuity pathway analysis (IPA) based on the Ingenuity Knowledge Base, we investigated signaling network that interacts with Jab1/COPS5. The data confirmed the important role of Jab1/COPS5 in tumorigenesis, demonstrating the potential of Jab1/COPS5 to be used as a biomarker for cancer patients, and further support that Jab1/COPS5 may serve as a potential therapeutic target in different cancers.

Suppression of Jab1 expression inhibits proliferation and promotes apoptosis of AMC-HN-8 cells.

c-Jun activation domain-binding protein-1 (Jab1) is a multifunctional protein involved in cell proliferation and apoptosis, DNA damage and repair and genome stability. In a number of types of human carcinoma, the abnormal expression of Jab1 is associated with poor prognosis, suggesting that Jab1 serves a vital function in tumorigenesis. However, the functional effects and the underlying molecular mechanisms of Jab1 in laryngeal squamous cell carcinoma (LSCC) progression remain poorly understood. The results of the present study demonstrate that downregulating Jab1 expression promotes LSCC apoptosis while inhibiting the proliferation of LSCC cells. Furthermore, Jab1 inhibition results in decreased protein kinase B phosphorylation accompanied by increased caspase-3 cleavage and p53 expression. It has been identified that the increased expression of Jab1 is markedly associated with LSCC progression, therefore Jab1 may be used as a novel target for the treatment of laryngeal cancer.

COPS5 and LASP1 synergistically interact to downregulate 14-3-3σ expression and promote colorectal cancer progression via activating PI3K/AKT pathway.

Overexpression of LIM and SH3 protein 1 (LASP1) is required for colorectal cancer (CRC) development and progression. Here, C-Jun activation domain-binding protein-1 (Jab1), also known as COP9 signalosome subunit 5 (COPS5), was verified as a new LASP1-interacting protein through yeast two-hybrid assay. The role of COPS5 in LASP1-mediated CRC progression remains unknown. GST pull-down assay indicated that the SH3 domain of LASP1 could directly bind to MPN domain of COPS5. In vitro gain- and loss-of-function analyses revealed the stimulatory role of COPS5 on CRC cell proliferation, migration and invasion. Endogenous overexpression of COPS5 could also enhance the homing capacity of CRC cells in vivo. Further analysis showed that COPS5 and LASP1 synergistically interact to stimulate the ubiquitination and degradation of 14-3-3σ and promote colorectal cancer progression via PI3K/Akt dependent signaling pathway. Clinically, the expression of COPS5 was studied in CRC tissues and it is associated with CRC differentiation, metastasis and poor prognosis. The colocalization of LASP1 and COPS5 was demonstrated in both nonmetastatic and metastatic CRC tissues. A positive correlation was found between the expression of LASP1 and COPS5 while a negative correlation existed between 14-3-3σ and COPS5/LASP1 in most CRC samples. A combination of COPS5 and LASP1 tends to be an independent prognostic indicator for CRC patients, and this is also suitable for CRC without lymph node metastasis. The current research has further advanced our understanding on the complicated molecular mechanism underlying LASP1-mediated CRC progression, which hopefully will contribute to the development of novel diagnostic and therapeutic strategies in CRC.