AP-1/c-Jun transcription factors: regulation and function in malignant melanoma

The hormonal control of parturition

Parturition is a complex physiological process that must occur in a reliable manner and at an appropriate gestation stage to ensure a healthy newborn and mother. To this end, hormones that affect the function of the gravid uterus, especially progesterone (P4), 17β-estradiol (E2), oxytocin (OT), and prostaglandins (PGs), play pivotal roles. P4 via the nuclear P4 receptor (PR) promotes uterine quiescence and for most of pregnancy exerts a dominant block to labor. Loss of the P4 block to parturition in association with a gain in prolabor actions of E2 are key transitions in the hormonal cascade leading to parturition. P4 withdrawal can occur through various mechanisms depending on species and physiological context. Parturition in most species involves inflammation within the uterine tissues and especially at the maternal-fetal interface. Local PGs and other inflammatory mediators may initiate parturition by inducing P4 withdrawal. Withdrawal of the P4 block is coordinated with increased E2 actions to enhance uterotonic signals mediated by OT and PGs to promote uterine contractions, cervix softening, and membrane rupture, i.e., labor. This review examines recent advances in research to understand the hormonal control of parturition, with focus on the roles of P4, E2, PGs, OT, inflammatory cytokines, and placental peptide hormones together with evolutionary biology of and implications for clinical management of human parturition.

Paclitaxel-induced Immune Dysfunction and Activation of Transcription Factor AP-1 Facilitate Hepatitis B Virus Replication

Background and Aims

Hepatitis B virus (HBV) reactivation is commonly observed in individuals with chronic HBV infection undergoing antineoplastic drug therapy. Paclitaxel (PTX) treatment has been identified as a potential trigger for HBV reactivation. This study aimed to uncover the mechanisms of PTX-induced HBV reactivation in vitro and in vivo, which may inform new strategies for HBV antiviral treatment.

Methods

The impact of PTX on HBV replication was assessed through various methods including enzyme-linked immunosorbent assay, dual-luciferase reporter assay, quantitative real-time PCR, chromatin immunoprecipitation, and immunohistochemical staining. Transcriptome sequencing and 16S rRNA sequencing were employed to assess alterations in the transcriptome and microbial diversity in PTX-treated HBV transgenic mice.

Results

PTX enhanced the levels of HBV 3.5-kb mRNA, HBV DNA, HBeAg, and HBsAg both in vitro and in vivo. PTX also promoted the activity of the HBV core promoter and transcription factor AP-1. Inhibition of AP-1 gene expression markedly suppressed PTX-induced HBV reactivation. Transcriptome sequencing revealed that PTX activated the immune-related signaling networks such as IL-17, NF-κB, and MAPK signaling pathways, with the pivotal common key molecule being AP-1. The 16S rRNA sequencing revealed that PTX induced dysbiosis of gut microbiota.

Conclusions

PTX-induced HBV reactivation was likely a synergistic outcome of immune suppression and direct stimulation of HBV replication through the enhancement of HBV core promoter activity mediated by the transcription factor AP-1. These findings propose a novel molecular mechanism, underscoring the critical role of AP-1 in PTX-induced HBV reactivation.

NONO promotes gallbladder cancer cell proliferation by enhancing oncogenic RNA splicing of DLG1 through interaction with IGF2BP3/RBM14

Gallbladder cancer (GBC) is a highly malignant and rapidly progressing tumor of the human biliary system, and there is an urgent need to develop new therapeutic targets and modalities. Non-POU domain-containing octamer-binding protein (NONO) is an RNA-binding protein involved in the regulation of transcription, mRNA splicing, and DNA repair. NONO expression is elevated in multiple tumors and can act as an oncogene to promote tumor progression. Here, we found that NONO was highly expressed in GBC and promoted tumor cells growth. The dysregulation of RNA splicing is a molecular feature of almost all tumor types. Accordingly, mRNA-seq and RIP-seq analysis showed that NONO promoted exon6 skipping in DLG1, forming two isomers (DLG1-FL and DLG1-S). Furthermore, lower Percent-Spliced-In (PSI) values of DLG1 were detected in tumor tissue relative to the paraneoplastic tissue, and were associated with poor patient prognosis. Moreover, DLG1-S and DLG1-FL act as tumor promoters and tumor suppressors, respectively, by regulating the YAP1/JUN pathway. N6-methyladenosine (m6A) is the most common and abundant RNA modification involved in alternative splicing processes. We identified an m6A reader, IGF2BP3, which synergizes with NONO to promote exon6 skipping in DLG1 in an m6A-dependent manner. Furthermore, IP/MS results showed that RBM14 was bound to NONO and interfered with NONO-mediated exon6 skipping of DLG1. In addition, IGF2BP3 disrupted the binding of RBM14 to NONO. Overall, our data elucidate the molecular mechanism by which NONO promotes DLG1 exon skipping, providing a basis for new therapeutic targets in GBC treatment.

Identification of aging-related genes in diagnosing osteoarthritis via integrating bioinformatics analysis and machine learning

BACKGROUND

Osteoarthritis (OA) is one of the main causes of pain and disability in the world, it may be caused by many factors. Aging plays a significant role in the onset and progression of OA. However, the mechanisms underlying it remain unknown. Our research aimed to uncover the role of aging-related genes in the progression of OA.

METHODS

In Human OA datasets and aging-related genes were obtained from the GEO database and the HAGR website, respectively. Bioinformatics methods including Gene Ontology (GO), Kyoto Encyclopedia of Genes Genomes (KEGG) pathway enrichment, and Protein-protein interaction (PPI) network analysis were used to analyze differentially expressed aging-related genes (DEARGs) in the normal control group and the OA group. And then weighted gene coexpression network analysis (WGCNA), the least absolute shrinkage and selection operator (LASSO) regression, and the Random Forest (RF) machine learning algorithms were used to find the hub genes.

RESULTS

Four overlapping hub genes: HMGB2, CDKN1A, JUN, and DDIT3 were identified. According to the nomogram model and receiver operating characteristic (ROC) curve analysis, four hub DEARGs had good diagnostic value in distinguishing normal from OA. Furthermore, the qRT-PCR test demonstrated that HMGB2, CDKN1A, JUN, and DDIT3 mRNA expression levels were lower in OA group than in normal group.

CONCLUSION

Finally, these four-hub aging-related genes may help us understand the underlying mechanism of aging in osteoarthritis and could be used as possible diagnostic and therapeutic targets.

20(S)-ginsenoside Rh2 inhibits angiotensin-2 mediated cardiac remodeling and inflammation associated with suppression of the JNK/AP-1 pathway

BACKGROUND

Enhanced levels of angiotensin-2 (Ang-II) causes hypertensive heart failure (HHF) through non-hemodynamical and hemodynamical alterations. 20(S)-ginsenoside Rh2 (20(S)-Rh2) is a natural ginseng compound with numerous cardiovascular benefits. This investigation elucidates the influence of 20(S)-Rh2 on Ang-II-induced heart failure and cardiac alterations.

METHODS

Ang-II was administered in C57BL/6 mice for 4 weeks to induce HHF. In the last 2 weeks of treatment, 20(S)-Rh2 was orally administered in mice to assess the potential 20(S)-Rh2 mechanism. Subsequently, RNA sequencing was carried out.

RESULTS

It was indicated that 20(S)-Rh2 suppresses myocardial fibrosis, hypertrophy, and inflammation, thereby inhibiting cardiac disruption in Ang-II-challenged mice without affecting blood pressure. According to the RNA sequencing data, this cardio-protective effect was linked with the (JNK)/AP 1 pathway. 20(S)-Rh2 alleviated heart tissue and cardiomyocytes inflammation by inhibiting the Ang-II-mediated JNK/AP-1 pathway. Within cardiomyocytes, JNK or AP-1 absence abolished the anti-inflammatory effects of 20(S)-Rh2.

CONCLUSION

This study investigation indicated that 20(S)-Rh2 prevents cardiovascular dysfunction induced by Ang-II induced by decreasing JNK-regulated inflammatory responses, providing evidence for its use as an efficient regimen for HHF.

Proteomics, Transcriptomics, and Phosphoproteomics Reveal the Mechanism of Talaroconvolutin-A Suppressing Bladder Cancer via Blocking Cell Cycle and Triggering Ferroptosis

Talaroconvolutin-A (TalaA) is a compound from the endophytic fungus T. convolutispora of the Chinese herbal medicine Panax notoginseng. Whether TalaA exerts anticancer activity in bladder cancer remains unknown. Using CCK8 assay, EdU staining, crystal violet staining, flow cytometry, living/dead cell staining, and Western blotting, we studied the anticancer activity of TalaA in vitro. Moreover, we performed xenograft tumor implantation. The antitumor effects were evaluated through H&E and immunohistochemistry staining. Proteomics was conducted to detect changes in the protein profile; transcriptomics was performed to detect changes in mRNA abundance; phosphoproteomics was used to detect changes in protein phosphorylation. TalaA inhibited tumor cell proliferation, DNA replication, and colony formation in a dose-dependent manner in bladder cancer cells. The IC50 values of TalaA on SW780 and UM-UC-3 cells were 5.7 and 8.2 μM, respectively. TalaA (6.0 mg/kg) significantly repressed the growth of xenografted tumors and did not affect the body weight nor cause obvious hepatorenal toxicity. TalaA arrested the cell cycle by downregulating cyclinA2, cyclinB1, and AURKB and upregulating p21/CIP. TalaA also elevated intracellular reactive oxygen species and upregulated transferrin and heme oxygenase 1 to induce ferroptosis. Moreover, TalaA was able to bind to MAPKs (MAPK1, MAPK8, and MAPK14) to inhibit the phosphorylation of ∗SP∗ motif of transcription regulators. This study revealed that TalaA inhibited bladder cancer by arresting cell cycle to suppress proliferation and triggering ferroptosis to cause cell death. Conclusively, TalaA would be a potential candidate for treating bladder cancer by targeting MAPKs, suppressing the cell cycle, and inducing ferroptosis.

Loss of DJ-1 function contributes to Parkinson's disease pathogenesis in mice via RACK1-mediated PKC activation and MAO-B upregulation

Parkinson's disease (PD) is a common neurodegenerative motor disorder characterized by a dramatic reduction in pars compacta of substantia nigra dopaminergic neurons and striatal dopamine (DA) levels. Mutations or deletions in the PARK7/DJ-1 gene are associated with an early-onset familial form of PD. DJ-1 protein prevents neurodegeneration via its regulation of oxidative stress and mitochondrial function as well as its roles in transcription and signal transduction. In this study, we investigated how loss of DJ-1 function affected DA degradation, ROS generation and mitochondrial dysfunction in neuronal cells. We showed that loss of DJ-1 significantly increased the expression of monoamine oxidase (MAO)-B but not MAO-A in both neuronal cells and primary astrocytes. In DJ-1-knockout (KO) mice, MAO-B protein levels in the substantia nigra (SN) and striatal regions were significantly increased. We demonstrated that the induction of MAO-B expression by DJ-1 deficiency depended on early growth response 1 (EGR1) in N2a cells. By coimmunoprecipitation omics analysis, we found that DJ-1 interacted with receptor of activated protein C kinase 1 (RACK1), a scaffolding protein, and thus inhibited the activity of the PKC/JNK/AP-1/EGR1 cascade. The PKC inhibitor sotrastaurin or the JNK inhibitor SP600125 completely inhibited DJ-1 deficiency-induced EGR1 and MAO-B expression in N2a cells. Moreover, the MAO-B inhibitor rasagiline inhibited mitochondrial ROS generation and rescued neuronal cell death caused by DJ-1 deficiency, especially in response to MPTP stimulation in vitro and in vivo. These results suggest that DJ-1 exerts neuroprotective effects by inhibiting the expression of MAO-B distributed at the mitochondrial outer membrane, which mediates DA degradation, ROS generation and mitochondrial dysfunction. This study reveals a mechanistic link between DJ-1 and MAO-B expression and contributes to understanding the crosslinks among pathogenic factors, mitochondrial dysfunction and oxidative stress in PD pathogenesis.

Development of a New Cell-Based AP-1 Gene Reporter Potency Assay for Anti-Anthrax Toxin Therapeutics

Anthrax toxin is a critical virulence factor of Bacillus anthracis. The toxin comprises protective antigen (PA) and two enzymatic moieties, edema factor (EF) and lethal factor (LF), forming bipartite lethal toxin (LT) and edema toxin (ET). PA binds cellular surface receptors and is required for intracellular translocation of the enzymatic moieties. For this reason, anti-PA antibodies have been developed as therapeutics for prophylaxis and treatment of human anthrax infection. Assays described publicly for the control of anti-PA antibody potency quantify inhibition of LT-mediated cell death or the ET-induced increase in c-AMP levels. These assays do not fully reflect and/or capture the pathological functions of anthrax toxin in humans. Herein, we report the development of a cell-based gene reporter potency assay for anti-PA antibodies based on the rapid LT-induced degradation of c-Jun protein, a pathogenic effect that occurs in human cells. This new assay was developed by transducing Hepa1c1c7 cells with an AP-1 reporter lentiviral construct and has been qualified for specificity, accuracy, repeatability, intermediate precision, and linearity. This assay not only serves as a bioassay for LT activity, but has applications for characterization and quality control of anti-PA therapeutic antibodies or other products that target the AP-1 signaling pathway.

WITHDRAWN: JUN and ATF3 are deficient in prostate cancer patients and their delivery in vivo via lipid nanoparticles has therapeutic efficacy by enhancing immune surveillance

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The potential of activator protein 1 (AP-1) in cancer targeted therapy

Activator protein-1 (AP-1) is a transcription factor that consists of a diverse group of members including Jun, Fos, Maf, and ATF. AP-1 involves a number of processes such as proliferation, migration, and invasion in cells. Dysfunctional AP-1 activity is associated with cancer initiation, development, invasion, migration and drug resistance. Therefore, AP-1 is a potential target for cancer targeted therapy. Currently, some small molecule inhibitors targeting AP-1 have been developed and tested, showing some anticancer effects. However, AP-1 is complex and diverse in its structure and function, and different dimers may play different roles in different type of cancers. Therefore, more research is needed to reveal the specific mechanisms of AP-1 in cancer, and how to select appropriate inhibitors and treatment strategies. Ultimately, this review summarizes the potential of combination therapy for cancer.

Localized immune surveillance of primary melanoma in the skin deciphered through executable modeling

While skin is a site of active immune surveillance, primary melanomas often escape detection. Here, we have developed an in silico model to determine the local cross-talk between melanomas and Langerhans cells (LCs), the primary antigen-presenting cells at the site of melanoma development. The model predicts that melanomas fail to activate LC migration to lymph nodes until tumors reach a critical size, which is determined by a positive TNF-α feedback loop within melanomas, in line with our observations of murine tumors. In silico drug screening, supported by subsequent experimental testing, shows that treatment of primary tumors with MAPK pathway inhibitors may further prevent LC migration. In addition, our in silico model predicts treatment combinations that bypass LC dysfunction. In conclusion, our combined approach of in silico and in vivo studies suggests a molecular mechanism that explains how early melanomas develop under the radar of immune surveillance by LC.

Kaempferol has potential anti-coronavirus disease 2019 (COVID-19) targets based on bioinformatics analyses and pharmacological effects on endotoxin-induced cytokine storm

COVID-19 has infected 272 million patients and caused 5.33 million deaths around the world, and it remains the main global threat. Previous studies revealed that Chinese traditional medicine is an effective treatment for COVID-19 infection. This study aims to reveal the pharmacological effects of kaempferol, which is the active component of Radix Bupleuri and Tripterygii Radix, and potential mechanisms for the treatment of COVID-19. Here, we employed the bioinformatics methods to filter the anti-COVID-19 candidate genes of kaempferol, which mainly enriched in inflammation (TNF, JUN, etc.) and virus infection (AKT1, JNK, etc.). The Transcription levels of AKT1, JNK and JUN were significantly reduced by kaempferol treatment in the LPS-activated macrophages. In addition, kaempferol reduced the secretion of inflammatory factors by LPS-stimulated macrophages, inhibited MAPK/NF-κB signaling and regulated macrophage polarization to M2 type in vitro, and suppressed endotoxin-induced cytokine storm and improved survival in mice. Molecular docking analysis demonstrated that kaempferol was probable to bind the COVID-19 protein 5R84 and formatted hydrogen bond with the residues, the free binding energy of which was lower than the original ligand. In summary, our current work indicates that kaempferol has anti-COVID-19 potential through the reduction of COVID-19-induced body dysfunction and molecule-protein interaction, and bioinformatics results clarify that some of these key target genes might serve as potential molecular markers for detecting COVID-19.

The complex network of transcription factors, immune checkpoint inhibitors and stemness features in colorectal cancer: A recent update

Cancer immunity is regulated by several mechanisms that include co-stimulatory and/or co-inhibitory molecules known as immune checkpoints expressed by the immune cells. In colorectal cancer (CRC), CTLA-4, LAG3, TIM-3 and PD-1 are the major co-inhibitory checkpoints involved in tumor development and progression. On the other hand, the deregulation of transcription factors and cancer stem cells activity plays a major role in the development of drug resistance and in the spread of metastatic disease in CRC. In this review, we describe how the modulation of such transcription factors affects the response of CRC to therapies. We also focus on the role of cancer stem cells in tumor metastasis and chemoresistance and discuss both preclinical and clinical approaches for targeting stem cells to prevent their tumorigenic effect. Finally, we provide an update on the clinical applications of immune checkpoint inhibitors in CRC and discuss the regulatory effects of transcription factors on the expression of the immune inhibitory checkpoints with specific focus on the PD-1 and PD-L1 molecules.

ATF6-Mediated Signaling Contributes to PARP Inhibitor Resistance in Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is the deadliest ovarian cancer histotype due in-part to the lack of therapeutic options for chemotherapy-resistant disease. PARP inhibitors (PARPi) represent a targeted treatment. However, PARPi resistance is becoming a significant clinical challenge. There is an urgent need to overcome resistance mechanisms to extend disease-free intervals. We established isogeneic PARPi-sensitive and -resistant HGSOC cell lines. In three PARPi-resistant models, there is a significant increase in AP-1 transcriptional activity and DNA repair capacity. Using RNA-sequencing and an shRNA screen, we identified activating transcription factor 6 (ATF6) as a mediator of AP-1 activity, DNA damage response, and PARPi resistance. In publicly available datasets, ATF6 expression is elevated in HGSOC and portends a poorer recurrence-free survival. In a cohort of primary HGSOC tumors, higher ATF6 expression significantly correlated to PARPi resistance. In PARPi-resistant cell lines and a PDX model, inhibition of a known ATF6 regulator, p38, attenuated AP-1 activity and RAD51 foci formation, enhanced DNA damage, significantly inhibited tumor burden, and reduced accumulation of nuclear ATF6.

IMPLICATIONS

This study highlights that a novel p38-ATF6-mediated AP-1 signaling axis contributes to PARPi resistance and provides a clinical rationale for combining PARPi and AP-1 signaling inhibitors.

PIK3R2 predicts poor outcomes for patients with melanoma and contributes to the malignant progression via PI3K/AKT/NF-κB axis

BACKGROUND

Melanoma is an aggressive form of skin cancer worldwide. Phosphoinositide-3-kinase regulatory subunit 2 (PIK3R2) exerts carcinogenic roles in various tumors. So far, the function and mechanism of PIK3R2 in melanoma are not been fully clarified.

OBJECTIVE

We aimed to clarify the role of PIK3R2 in melanoma.

METHODS

PIK3R2 expressions in melanoma clinical tissues and melanoma cells were measured using quantitative real-time PCR and Western blot. In addition, PIK3R2 expressions in different tumor stages of melanoma were determined by immunohistochemistry assay. Meanwhile, PIK3R2 function was evaluated using loss or gain-of-function assays, Cell Counting Kit-8 assay, flow cytometry, and Transwell analysis. Furthermore, PIK3R2 mechanism in melanoma was assessed by a series of rescue experiments.

RESULTS

PIK3R2 was highly expressed in melanoma tissues and cells, and PIK3R2 expressions were the highest in Stage IV. Functionally, PIK3R2 knockdown repressed melanoma cell proliferation, invasion, epithelial-mesenchymal transition, and facilitated cell apoptosis. Also, PIK3R2 overexpression produced an opposite trend. Mechanistically, PIK3R2 facilitated melanoma progression by activating PI3K/AKT/NF-κB pathway. Furthermore, PIK3R2 knockdown restrained the melanoma tumor growth in vivo.

CONCLUSIONS

PIK3R2 aggravated melanoma by activating PI3K/AKT/NF-κB pathway, prompting that PIK3R2 might be a therapeutic target for melanoma.

The Potential Role of Fisetin, a Flavonoid in Cancer Prevention and Treatment

Cancer is a main culprit and the second-leading cause of death worldwide. The current mode of treatment strategies including surgery with chemotherapy and radiation therapy may be effective, but cancer is still considered a major cause of death. Plant-derived products or their purified bioactive compounds have confirmed health-promoting effects as well as cancer-preventive effects. Among these products, flavonoids belong to polyphenols, chiefly found in fruits, vegetables and in various seeds/flowers. It has been considered to be an effective antioxidant, anti-inflammatory and to play a vital role in diseases management. Besides these activities, flavonoids have been revealed to possess anticancer potential through the modulation of various cell signaling molecules. In this regard, fisetin, a naturally occurring flavonoid, has a confirmed role in disease management through antioxidant, neuro-protective, anti-diabetic, hepato-protective and reno-protective potential. As well, its cancer-preventive effects have been confirmed via modulating various cell signaling pathways including inflammation, apoptosis, angiogenesis, growth factor, transcription factor and other cell signaling pathways. This review presents an overview of the anti-cancer potential of fisetin in different types of cancer through the modulation of cell signaling pathways based on in vivo and in vitro studies. A synergistic effect with anticancer drugs and strategies to improve the bioavailability are described. More clinical trials need to be performed to explore the anti-cancer potential and mechanism-of-action of fisetin and its optimum therapeutic dose.

The traditional chinese medicine monomer Ailanthone improves the therapeutic efficacy of anti-PD-L1 in melanoma cells by targeting c-Jun

BACKGROUND

C-Jun, a critical component of AP-1, exerts essential functions in various tumors, including melanoma, and is believed to be a druggable target for cancer therapy. Unfortunately, no effective c-Jun inhibitors are currently approved for clinical use. The advent of immune checkpoint inhibitor (ICI) has brought a paradigm shift in melanoma therapy, but more than half of patients fail to exhibit clinical responses. The exploration of new combination therapies has become the current pursuit of melanoma treatment strategy. This study aims to screen out Chinese herbal monomers that can target c-Jun, explore the combined effect of c-Jun inhibitor and ICI, and further clarify the related molecular mechanism.  METHODS: We adopted a combinatorial screening strategy, including molecular docking, ligand-based online approaches and consensus quantitative structure-activity relationship (QSAR) model, to filter out c-Jun inhibitors from a traditional Chinese medicine (TCM) library. A mouse melanoma model was used to evaluate the therapeutic efficacy of monotherapy and combination therapy. Multicolor flow cytometry was employed to assess the tumor microenvironment (TME). Multiple in vitro assays were performed to verify down-streaming signaling pathway. CD4 + T-cell differentiation assay was applied to investigate Treg differentiation in vitro.

RESULTS

Ailanthone (AIL) was screened out as a c-Jun inhibitor, and inhibited melanoma cell growth by directly targeting c-Jun and promoting its degradation. Surprisingly, AIL also facilitated the therapeutic efficacy of anti-programmed death ligand-1 (PD-L1) in melanoma cells by reducing the infiltration of Tregs in TME. Additionally, AIL treatment inhibited c-Jun-induced PD-L1 expression and secretion. As a consequence, Treg differentiation was attenuated after treatment with AIL through the c-Jun/PD-L1 axis.

CONCLUSION

Our findings identified AIL as a novel c-Jun inhibitor, and revealed its previously unrecognized anti-melanoma effects and the vital role in regulating TME by Treg suppression, which provides a novel combination therapeutic strategy of c-Jun inhibition by AIL with ICI. AIL down-regulates c-Jun by reducing its stability, and inhibits the function of Tregs via AIL-c-Jun-PD-L1 pathway, ultimately suppressing melanoma progression and enhancing the efficacy of anti-PD-L1.

Coexpression of c-Jun in multiple-chain DAP-CAR-engineered T-cells for solid tumor therapy

Aim: This work was designed to explore whether c-Jun overexpression could improve the persistence and antitumor efficacy of DAP chimeric antigen receptor T-cell (CAR-T) cells. Methods: The in vitro and in vivo antitumor effects of mesothelin (MSLN) targeting DAP-CAR-T cells were verified by ELISA, real-time cell analysis and in a xenograft model. Results: c-Jun overexpression did not affect DAP-CAR-T cell expansion while slightly increasing IL-2 secretion. Moreover, c-Jun did not improve the antitumor efficacy of DAP-CAR-T cells in vitro or in vivo, but reduced LAG3 expression and increased the ratio of Tcm and Tn/Tscm cells in vivo. Conclusion: The findings indicate that coexpression with c-Jun in DAP-CAR-T cells slightly improves T-cell exhaustion and central memory phenotype maintenance, which may be useful for DAP-CAR-T cell therapy in solid tumors.

Ferroptosis-Related Proteins Are Potential Diagnostic Molecular Markers for Patients with Preeclampsia

Preeclampsia (PE) is the leading cause of maternal and fetal mortality and morbidity. Early and accurate diagnosis is critical to reduce mortality. Placental oxidative stress has been identified as a major pathway to the development of PE. Ferroptosis, a new form of regulated cell death, is associated with iron metabolism and oxidative stress, and has been suspected to play a role in the pathophysiology of PE, although the mechanism is yet to be elucidated. The identification of potential ferroptosis-related biomarkers is of great significance for the early diagnosis and treatment of PE. A gene expression dataset of peripheral blood samples was downloaded from the Gene Expression Omnibus (GEO) dataset. Differentially expressed genes (DEGs) were filtrated with the R package “limma”. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs were then conducted. Ferroptosis-related DEGs were screened by overlapping the ferroptosis-related genes with DEGs. The protein−protein interaction (PPI) network was used to identify the key ferroptosis-related DEGs. Enzyme-linked immunosorbent assay (ELISA) was used to validate changes in the selected key ferroptosis-related DEGs. The correlations between the key genes and clinical and pathological characteristics were analyzed. Finally, the diagnostic value of these key genes for PE was confirmed by a receiver operating characteristic (ROC) curve. A total of 5913 DEGs were identified and 45 ferroptosis-related DEGs were obtained. Besides, ferroptosis-related pathways were enriched by KEGG using DEGs. The PPI network showed that p53 and c-Jun were the critical hub genes. ELISA showed that p53 in the serum of PE patients was higher than that of the control group, while c-Jun was lower than that of the control group. Analysis of the clinicopathological features showed that p53 and c-Jun were correlated with the PE characteristics. Finally, based on the area under curve (AUC) values, c-Jun had the superior diagnostic power (AUC = 0.87, p < 0.001), followed by p53 (AUC = 0.75, p < 0.001). Our study identified that two key genes, p53 and c-Jun, might be potential diagnostic biomarkers of PE.

PKC is an indispensable factor in promoting environmental toxin chromium-mediated transformation and drug resistance

Hexavalent chromium [Cr(VI)] pollution is a serious environmental problem, due to not only its toxicity but also carcinogenesis. Although studies reveal several features of Cr(VI)-induced carcinogenesis, the underlying mechanisms of how Cr(VI) orchestrates multiple mitogenic pathways to promote tumor initiation and progression remain not fully understood. Src/Ras and other growth-related pathways are shown to be key players in Cr(VI)-initiated tumor prone actions. The role of protein kinase C (PKC, an important signal transducer) in Cr(VI)-mediated carcinogenesis has not been thoroughly investigated. In this study, using human bronchial/lung epithelial cells and keratinocytes, we demonstrate that PKC activity is increased by transient or chronic Cr(VI) exposure, which plays no role in the activation of Src/Ras signaling and ROS upregulation by this metal toxin. PKC in chronic Cr(VI)-treated cells stabilizes Bcl-2 to mitigate doxorubicin (an anti-cancer drug)-mediated apoptosis. After the suppression of this kinase by GO6976 (a PKC inhibitor), the cells chronically exposed to Cr(VI) partially regain the sensitivity to doxorubicin. However, when co-suppressed PKC and Ras, the chronic Cr(VI)-treated cells become fully responsive to doxorubicin and are unable to be transformed. Taken together, our study provides a new insight into the mechanisms, in which PKC is an indispensable player and cooperates with other mitogenic pathways to achieve Cr(VI)-induced carcinogenesis as well as to establish drug resistance. The data also suggest that active PKC can serve as a potential biomarker for early detection of health damages by Cr(VI) and therapeutic target for developing new treatments for diseases caused by Cr(VI).

Induction of ZIP8, a ZIP transporter, via NF-κB signaling by the activation of IκBα and JNK signaling in cultured vascular endothelial cells exposed to cadmium

Cadmium is an environmental pollutant that adversely affects various organs in the human body and is a well-known risk factor for cardiovascular diseases. These disorders are caused by the dysfunction of the vascular endothelial cells that cover the luminal surface of blood vessels. The ZIP transporter ZIP8 is one of the primary importers of cadmium, and its expression appears to be important for the sensitivity of vascular endothelial cells to cadmium. In the present study, we investigated the influence of ZIP8 on cadmium-induced cytotoxicity in vascular endothelial cells, the induction of ZIP8 expression by cadmium, and its action mechanism in vascular endothelial cells. The study revealed that: (1) cadmium cytotoxicity in vascular endothelial cells was potentiated by the overexpression of ZIP8, and the intracellular accumulation of cadmium in the cells was increased; (2) cadmium highly induced the expression of ZIP8, but not other ZIPs; (3) lead and methylmercury moderately induced ZIP8 expression, but the other tested metals did not; (4) the induction of ZIP8 expression by cadmium was mediated by both NF-κB and JNK signaling, and the accumulation of NF-κB in the nucleus was regulated by JNK signaling. Particularly, it was found that cadmium activated NF-κB to transfer it into nuclei and activated JNK to stabilize NF-κB in nuclei, resulting in the induction of ZIP8 expression. This induction appears to be crucial for cadmium cytotoxicity in vascular endothelial cells.

Strategies for Improving Photodynamic Therapy Through Pharmacological Modulation of the Immediate Early Stress Response

Photodynamic therapy (PDT) is a minimally to noninvasive treatment modality that has emerged as a promising alternative to conventional cancer treatments. PDT induces hyperoxidative stress and disrupts cellular homeostasis in photosensitized cancer cells, resulting in cell death and ultimately removal of the tumor. However, various survival pathways can be activated in sublethally afflicted cancer cells following PDT. The acute stress response is one of the known survival pathways in PDT, which is activated by reactive oxygen species and signals via ASK-1 (directly) or via TNFR (indirectly). The acute stress response can activate various other survival pathways that may entail antioxidant, pro-inflammatory, angiogenic, and proteotoxic stress responses that culminate in the cancer cell's ability to cope with redox stress and oxidative damage. This review provides an overview of the immediate early stress response in the context of PDT, mechanisms of activation by PDT, and molecular intervention strategies aimed at inhibiting survival signaling and improving PDT outcome.

Remodeling tumor microenvironment by liposomal codelivery of DMXAA and simvastatin inhibits malignant melanoma progression

Anti-angiogenic therapies for melanoma have not yet been translated into meaningful clinical benefit for patients, due to the development of drug-induced resistance in cancer cells, mainly caused by hypoxia-inducible factor 1α (HIF-1α) overexpression and enhanced oxidative stress mediated by tumor-associated macrophages (TAMs). Our previous study demonstrated synergistic antitumor actions of simvastatin (SIM) and 5,6-dimethylxanthenone-4-acetic acid (DMXAA) on an in vitro melanoma model via suppression of the aggressive phenotype of melanoma cells and inhibition of TAMs-mediated angiogenesis. Therefore, we took the advantage of long circulating liposomes (LCL) superior tumor targeting capacity to efficiently deliver SIM and DMXAA to B16.F10 melanoma in vivo, with the final aim of improving the outcome of the anti-angiogenic therapy. Thus, we assessed the effects of this novel combined tumor-targeted treatment on s.c. B16.F10 murine melanoma growth and on the production of critical markers involved in tumor development and progression. Our results showed that the combined liposomal therapy almost totally inhibited (> 90%) the growth of melanoma tumors, due to the enhancement of anti-angiogenic effects of LCL-DMXAA by LCL-SIM and simultaneous induction of a pro-apoptotic state of tumor cells in the tumor microenvironment (TME). These effects were accompanied by the partial re-education of TAMs towards an M1 phenotype and augmented by combined therapy-induced suppression of major invasion and metastasis promoters (HIF-1α, pAP-1 c-Jun, and MMPs). Thus, this novel therapy holds the potential to remodel the TME, by suppressing its most important malignant biological capabilities.

Machine learning implicates the IL-18 signaling axis in severe asthma

Asthma is a common disease with profoundly variable natural history and patient morbidity. Heterogeneity has long been appreciated, and much work has focused on identifying subgroups of patients with similar pathobiological underpinnings. Previous studies of the Severe Asthma Research Program (SARP) cohort linked gene expression changes to specific clinical and physiologic characteristics. While invaluable for hypothesis generation, these data include extensive candidate gene lists that complicate target identification and validation. In this analysis, we performed unsupervised clustering of the SARP cohort using bronchial epithelial cell gene expression data, identifying a transcriptional signature for participants suffering exacerbation-prone asthma with impaired lung function. Clinically, participants in this asthma cluster exhibited a mixed inflammatory process and bore transcriptional hallmarks of NF-κB and activator protein 1 (AP-1) activation, despite high corticosteroid exposure. Using supervised machine learning, we found a set of 31 genes that classified patients with high accuracy and could reconstitute clinical and transcriptional hallmarks of our patient clustering in an external cohort. Of these genes, IL18R1 (IL-18 Receptor 1) negatively associated with lung function and was highly expressed in the most severe patient cluster. We validated IL18R1 protein expression in lung tissue and identified downstream NF-κB and AP-1 activity, supporting IL-18 signaling in severe asthma pathogenesis and highlighting this approach for gene and pathway discovery.

Melanoma Plasticity: Promoter of Metastasis and Resistance to Therapy

Melanoma is the deadliest form of skin cancer. Although targeted therapies and immunotherapies have revolutionized the treatment of metastatic melanoma, most patients are not cured. Therapy resistance remains a significant clinical challenge. Melanoma comprises phenotypically distinct subpopulations of cells, exhibiting distinct gene signatures leading to tumor heterogeneity and favoring therapeutic resistance. Cellular plasticity in melanoma is referred to as phenotype switching. Regardless of their genomic classification, melanomas switch from a proliferative and differentiated phenotype to an invasive, dedifferentiated and often therapy-resistant state. In this review we discuss potential mechanisms underpinning melanoma phenotype switching, how this cellular plasticity contributes to resistance to both targeted therapies and immunotherapies. Finally, we highlight novel strategies to target plasticity and their potential clinical impact in melanoma.

Identification of key regulators responsible for dysregulated networks in osteoarthritis by large-scale expression analysis

BACKGROUND

Osteoarthritis (OA) is a worldwide musculoskeletal disorder. However, disease-modifying therapies for OA are not available. Here, we aimed to characterize the molecular signatures of OA and to identify novel therapeutic targets and strategies to improve the treatment of OA.

METHODS

We collected genome-wide transcriptome data performed on 132 OA and 74 normal human cartilage or synovium tissues from 7 independent datasets. Differential gene expression analysis and functional enrichment were performed to identify genes and pathways that were dysregulated in OA. The computational drug repurposing method was used to uncover drugs that could be repurposed to treat OA.

RESULTS

We identified several pathways associated with the development of OA, such as extracellular matrix organization, inflammation, bone development, and ossification. By protein-protein interaction (PPI) network analysis, we prioritized several hub genes, such as JUN, CDKN1A, VEGFA, and FOXO3. Moreover, we repurposed several FDA-approved drugs, such as cardiac glycosides, that could be used in the treatment of OA.

CONCLUSIONS

We proposed that the hub genes we identified would play a role in cartilage homeostasis and could be important diagnostic and therapeutic targets. Drugs such as cardiac glycosides provided new possibilities for the treatment of OA.

Erk1/2 Inactivation-Induced c-Jun Degradation Is Regulated by Protein Phosphatases, UBE2d3, and the C-Terminus of c-Jun

Constitutive photomorphogenic 1 (COP1) is the ubiquitin E3 ligase that mediates degradation of c-Jun protein upon Erk1/2 inactivation. It remains unknown how this protein degradation pathway is regulated. In this study, we investigated the roles of protein phosphatases, ubiquitin-conjugating E2 enzymes (UBE2), and an intrinsic motif of c-Jun in regulating this degradation pathway. By using pharmacological inhibitors and/or gene knockdown techniques, we identified protein phosphatase 1 (PP1) and PP2A as the phosphatases and UBE23d as the UBE2 promoting c-Jun degradation, triggered by Erk1/2 inactivation. In addition, we report that the C-terminus of c-Jun protein facilitates its degradation. The addition of a C-terminal tag or deletion of the last four amino acid residues from the C-terminus of c-Jun protects it from degradation under Erk1/2-inactivating conditions. Taken together, this study reveals that the Erk1/2 inactivation-triggered and COP1-mediated c-Jun degradation is extrinsically and intrinsically regulated, providing a new understanding of the mechanisms underlying this protein degradation pathway.

Olig2 regulates p53-mediated apoptosis, migration and invasion of melanoma cells

Melanoma is a disease with a high recurrence rate and poor prognosis; therefore, the need for targeted therapeutics is steadily increasing. Oligodendrocyte transcription factor2 (Olig2) is a basic helix-loop-helix transcription factor that is expressed in the central nervous system during embryonic development. Olig2 is overexpressed in various malignant cell lines such as lung carcinoma, glioma and melanoma. Olig2 is known as a key transcription factor that promotes tumor growth in malignant glioma. However, the role of Olig2 in melanoma is not well characterized. We analyzed the role of Olig2 in apoptosis, migration, and invasion of melanoma cells. We confirmed that Olig2 was overexpressed in melanoma cells and tissues. Reduction of Olig2 increased apoptosis in melanoma cells by increasing p53 level and caspase-3/-7 enzyme activity. In addition, downregulation of Olig2 suppressed migration and invasion of melanoma cells by inhibiting EMT. Reduction of Olig2 inhibited expression of MMP-1 and the enzyme activity of MMP-2/-9 induced by TGF-β. Moreover, Olig2 was involved in the downstream stages of MEK/ERK and PI3K/AKT, which are major signaling pathways in metastatic progression of melanoma. In conclusion, this study demonstrated the crucial roles of Olig2 in apoptosis, migration, and invasion of melanoma and may help to further our understanding of the relationship between Olig2 and melanoma progression.

SMARCA4 promotes benign skin malignant transformation into melanoma through Adherens junction signal transduction

PURPOSE

Melanoma is a malignant skin tumor, and its incidence is rising. To explore the specific differences in benign and malignant melanoma at the genetic level, we performed a series of bioinformatics analyses, including differential gene analysis, co-expression analysis, enrichment analysis, and regulatory prediction.

METHODS

The microarray data of benign and malignant melanocytes were downloaded from GEO, and 1917 differential genes were obtained by differential analysis (p < 0.05). Weighted gene co-expression network analysis obtained three functional barrier modules. The essential genes of each module are SMARTA4, HECA, and C1R.

RESULTS

The results of the enrichment analysis showed that the dysfunctional module gene was mainly associated with RNA splicing and Adherens junction. Through the pivotal analysis of ncRNA, it was found that miR-448, miR-152-3p, and miR-302b-3p essentially regulate three modules, which we consider to be critical regulators. In the pivot analysis of TF, more control modules include ARID3A, E2F1, E2F3, and E2F8.

CONCLUSIONS

We believe that the regulator (miR-448, miR-152-3p, miR-302b-3p) regulates the expression of the core gene SMARCA4, which in turn affects the signal transduction of the Adherens junction. It eventually leads to the deterioration of benign skin spasms into melanoma.

PKCδ mediates mitochondrial ROS generation and oxidation of HSP60 to relieve RKIP inhibition on MAPK pathway for HCC progression

Both protein kinase C (PKC) and reactive oxygen species (ROS) are well-known signaling messengers cross-talking with each other to activate mitogen-activated protein kinases (MAPKs) for progression of hepatocellular carcinoma (HCC). However, the underlying mechanisms are not well elucidated. Especially, whether mitochondrial ROS (mtROS) is involved and how it triggers MAPK signaling are intriguing. In this study, we found mtROS generation and phosphorylation of MAPKs were mediated by PKCδ in HCCs treated with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Heat shock protein 60 (HSP60), one of the chaperones in mitochondria was the major protein oxidized in TPA-treated HCCs. Moreover, depletion of HSP60 or expression of HSP60 cysteine mutant prevented TPA-induced phosphorylation of MAPKs. To delineate how HSP60 mediated MAPK activation, the role of Raf kinase inhibitor protein (RKIP), a negative regulator of MAPK, was investigated. TPA dissociated RKIP from HSP60 in both mitochondria and cytosol, concurrently with translocation of HSP60 and MAPK from mitochondria to cytosol, which was associated with robust phosphorylation of MAPKs in the cytosol. Moreover, TPA induced opposite phenotypical changes of HCCs, G1 cell cycle arrest, and cell migration, which were prevented by mtROS scavengers and depletion of PKCδ and HSP60. Consistently, TPA increased the migration-related genes, hydrogen peroxide inducible clone5, matrix metalloproteinase-1/3, lamininγ2, and suppressed the cell cycle regulator cyclin E1 (CCNE1) via PKCδ/mtROS/HSP60/MAPK-axis. Finally, c-jun and c-fos were required for TPA-induced expression of the migration-related genes and a novel microRNA, miR-6134, was responsible for TPA-induced suppression of CCNE1. In conclusion, PKCδ cross-talked with mtROS to trigger HSP60 oxidation for release of RKIP to activate MAPK, regulating gene expression for migration, and G1 cell cycle arrest in HCC. Targeted therapy aiming at key players like PKCδ, RKIP, and HSP60 is promising for preventing HCC progression.

AP-1 family transcription factors: a diverse family of proteins that regulate varied cellular activities in classical hodgkin lymphoma and ALK+ ALCL

Classical Hodgkin lymphoma (cHL) and anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL) are B and T cell lymphomas respectively, which express the tumour necrosis factor receptor superfamily member, CD30. Another feature shared by cHL and ALK+ ALCL is the aberrant expression of multiple members of the activator protein-1 (AP-1) family of transcription factors which includes proteins of the Jun, Fos, ATF, and Maf subfamilies. In this review, we highlight the varied roles these proteins play in the pathobiology of these lymphomas including promoting proliferation, suppressing apoptosis, and evading the host immune response. In addition, we discuss factors contributing to the elevated expression of these transcription factors in cHL and ALK+ ALCL. Finally, we examine therapeutic strategies for these lymphomas that exploit AP-1 transcriptional targets or the signalling pathways they regulate.

AFF4 facilitates melanoma cell progression by regulating c-Jun activity

Melanoma is characterized by high mortality and poor prognosis due to metastasis. AFF4 (AF4/FMR2 family member 4), as a scaffold protein, is a component of the super elongation complex (SEC), and is involved in the progression of tumors, e.g., leukemia, head and neck squamous cell carcinoma (HNSCC). However, few studies on AFF4 have focused on melanoma. Here, AFF4 expression levels and clinicopathological features were evaluated in melanoma tissue samples. Then, we performed cell proliferation, migration and invasion assays in A375 and A2058 cells lines in vitro to evaluate the role of AFF4 in melanoma. The effects of AFF4 knockdown in vivo were characterized via a xenograft mouse model. Finally, the correlation between c-Jun and AFF4 protein levels in melanoma was analyzed by rescue assay and immunohistochemistry (IHC). We found that AFF4 expression was upregulated in melanoma tumor tissues and that AFF4 protein expression was also closely related to the prognosis of patients with cutaneous melanoma. Moreover, AFF4 could promote the invasion and migration of melanoma cells by mediating epithelial to mesenchymal transition (EMT). AFF4 might regulate c-Jun activity to promote the invasion and migration of melanoma cells. Importantly, c-Jun was regulated by the AFF4 promoted melanoma tumorigenesis in vivo. Taken together, AFF4 may be a novel oncogene that promotes melanoma progression through regulation of c-Jun activity.

Re-expression of SMARCA4/BRG1 in small cell carcinoma of ovary, hypercalcemic type (SCCOHT) promotes an epithelial-like gene signature through an AP-1-dependent mechanism

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and aggressive form of ovarian cancer. SCCOHT tumors have inactivating mutations in SMARCA4 (BRG1), one of the two mutually exclusive ATPases of the SWI/SNF chromatin remodeling complex. To address the role that BRG1 loss plays in SCCOHT tumorigenesis, we performed integrative multi-omic analyses in SCCOHT cell lines +/- BRG1 reexpression. BRG1 reexpression induced a gene and protein signature similar to an epithelial cell and gained chromatin accessibility sites correlated with other epithelial originating TCGA tumors. Gained chromatin accessibility and BRG1 recruited sites were strongly enriched for transcription-factor-binding motifs of AP-1 family members. Furthermore, AP-1 motifs were enriched at the promoters of highly upregulated epithelial genes. Using a dominant-negative AP-1 cell line, we found that both AP-1 DNA-binding activity and BRG1 reexpression are necessary for the gene and protein expression of epithelial genes. Our study demonstrates that BRG1 reexpression drives an epithelial-like gene and protein signature in SCCOHT cells that depends upon by AP-1 activity.

Transcription factors in colorectal cancer: molecular mechanism and therapeutic implications

Colorectal cancer (CRC) is a major cause of cancer mortality worldwide, however, the molecular mechanisms underlying the pathogenesis of CRC remain largely unclear. Recent studies have revealed crucial roles of transcription factors in CRC development. Transcription factors essential for the regulation of gene expression by interacting with transcription corepressor/enhancer complexes and they orchestrate downstream signal transduction. Deregulation of transcription factors is a frequent occurrence in CRC, and the accompanying drastic changes in gene expression profiles play fundamental roles in multistep process of tumorigenesis, from cellular transformation, disease progression to metastatic disease. Herein, we summarized current and emerging key transcription factors that participate in CRC tumorigenesis, and highlighted their oncogenic or tumor suppressive functions. Moreover, we presented critical transcription factors of CRC, emphasized the major molecular mechanisms underlying their effect on signal cascades associated with tumorigenesis, and summarized of their potential as molecular biomarkers for CRC prognosis therapeutic response, as well as drug targets for CRC treatment. A better understanding of transcription factors involved in the development of CRC will provide new insights into the pathological mechanisms and reveal novel prognostic biomarkers and therapeutic strategies for CRC.

Role of the Receptor for Advanced Glycation End Products in Heat Stress-Induced Endothelial Hyperpermeability in Acute Lung Injury

Objective

To study the role of the receptor for advanced glycation end products (RAGE) in endothelial barrier dysfunction induced by heat stress, to further explore the signal pathway by which RAGE contributes to heat-induced endothelia response, and thereby find a novel target for the clinical treatment of ALI (acute lung injury) induced by heatstroke.

Methods

This study established the animal model of heatstroke using RAGE knockout mice. We observed the role of RAGE in acute lung injury induced by heatstroke in mice by evaluating the leukocytes, neutrophils, and protein concentration in BALF (Bronchoalveolar lavage fluids), lung wet/dry ratio, histopathological changes, and the morphological ultrastructure of lung tissue and arterial blood gas analysis. To further study the mechanism, we established a heat stress model of HUVEC and concentrated on the role of RAGE and its signal pathway in the endothelial barrier dysfunction induced by heat stress, measuring Transendothelial electrical resistance (TEER) and western blot.

Results

RAGE played a key role in acute lung injury induced by heatstroke in mice. The mechanism C-Jun is located in the promoter region of the RAGE gene. C-Jun increased the RAGE protein expression while HSF1 suppressed RAGE protein expression. The overexpressed RAGE protein then increased HUVEC monolayer permeability by activating ERK and P38 MAPK under heat stress.

Conclusion

This study indicates the critical role of RAGE in heat stress-induced endothelial hyperpermeability in acute lung injury and suggests that RAGE could be a potential therapeutic target in protecting patients against acute lung injury induced by heatstroke.

Fra-2/AP-1 regulates melanoma cell metastasis by downregulating Fam212b

Metastatic melanoma remains a challenging disease. Understanding the molecular mechanisms how melanoma becomes metastatic is therefore of interest. Herein we show that downregulation of the AP-1 transcription factor member Fra-2 in melanoma cells is associated with an aggressive melanoma phenotype in vitro and in vivo. In vitro, Fra-2 knockdown in melanoma cells promoted cell migration and invasion associated with increased Snail-1, Twist-1/2, and matrix metalloproteinase-2 (MMP-2) expression. In vivo, Fra-2 knockdown in a melanoma cell line led to increased metastasis into the lungs and liver. The increased metastatic potential of Fra-2 knockdown melanoma cells was likely due to an accelerated cell cycle transition and increased tissue angiogenesis. Using Fra-2 knockdown cell lines microarray analysis, we identified the protein Fam212b (family with sequence similarity 212 member B) as a downstream target of Fra-2. By additional knockdown of Fam212b in Fra-2 mutant cells, we mitigated the cell migration, invasion, and cell cycle transition phenotype induced by Fra-2 knockdown. Furthermore, Fam212b overexpression enhanced β-catenin pathway. Finally, Fam212b expression is correlated with increased melanoma metastasis and poor clinical outcomes in human patients. In summary, these findings reveal the Fra-2-Fam212b axis as a new pathway of melanoma metastasis, which can be in the future used as potential marker of the metastatic properties of melanoma.

The Multifaceted Output of c-Jun Biological Activity: Focus at the Junction of CD8 T Cell Activation and Exhaustion

c-Jun is a major component of the dimeric transcription factor activator protein-1 (AP-1), a paradigm for transcriptional response to extracellular signaling, whose components are basic-Leucine Zipper (bZIP) transcription factors of the Jun, Fos, activating transcription factor (ATF), ATF-like (BATF) and Jun dimerization protein 2 (JDP2) gene families. Extracellular signals regulate c-Jun/AP-1 activity at multiple levels, including transcriptional and posttranscriptional regulation of c-Jun expression and transactivity, in turn, establishing the magnitude and the duration of c-Jun/AP-1 activation. Another important level of c-Jun/AP-1 regulation is due to the capability of Jun family members to bind DNA as a heterodimer with every other member of the AP-1 family, and to interact with other classes of transcription factors, thereby acquiring the potential to integrate diverse extrinsic and intrinsic signals into combinatorial regulation of gene expression. Here, we review how these features of c-Jun/AP-1 regulation underlie the multifaceted output of c-Jun biological activity, eliciting quite distinct cellular responses, such as neoplastic transformation, differentiation and apoptosis, in different cell types. In particular, we focus on the current understanding of the role of c-Jun/AP-1 in the response of CD8 T cells to acute infection and cancer. We highlight the transcriptional and epigenetic regulatory mechanisms through which c-Jun/AP-1 participates in the productive immune response of CD8 T cells, and how its downregulation may contribute to the dysfunctional state of tumor infiltrating CD8 T cells. Additionally, we discuss recent insights pointing at c-Jun as a suitable target for immunotherapy-based combination approaches to reinvigorate anti-tumor immune functions.

Pyruvate Kinase M2 Promotes Prostate Cancer Metastasis Through Regulating ERK1/2-COX-2 Signaling

Pyruvate kinase M2 (PKM2) is a key enzyme of glycolysis, which is highly expressed in many tumor cells, and has emerged as an important player in tumor progression and metastasis. However, the functional roles of PKM2 in tumor metastasis remain elusive. Here we showed that PKM2 promoted prostate cancer metastasis via extracellular-regulated protein kinase (ERK)-cyclooxygenase (COX-2) signaling. Based on public databases, we found that PKM2 expression was upregulated in prostate cancer and positively associated with tumor metastasis. Further analysis showed that PKM2 promoted prostate cancer cell migration/invasion and epithelial-mesenchymal transition (EMT) through upregulation of COX-2. Mechanistically, PKM2 interacted with ERK1/2 and regulated its phosphorylation, leading to phosphorylation of transcription factor c-Jun, downstream of ERK1/2, to activate COX-2 transcription by IP and ChIP assay, while inhibition of COX-2 significantly reversed the promotion effect of PKM2 on tumor metastasis in vivo. Taken together, our results suggest that a novel of PKM2-ERK1/2-c-Jun-COX-2 axis is a potential target in controlling prostate cancer metastasis.

The c-Jun signaling pathway has a protective effect on nucleus pulposus cells in patients with intervertebral disc degeneration

Among a range of diverse clinical symptoms, intervertebral disc degeneration (IDD) contributes mostly to the onset of lower back pain. The present study aimed to investigate the effects of c-Jun on nucleus pulposus (NP) cells of IDD and its regulation on molecular mechanisms. Intervertebral disc (IVD) tissues were collected from patients suffering from IDD disease, and NP cells were subsequently isolated and cultured. By overexpressing c-Jun in NP cells, expression levels of mRNAs and proteins of IDD-related genes and inflammatory cytokines were subjected to reverse transcription-quantitative PCR, western blot and ELISA assays. Additional transforming growth factor-β (TGF-β) antibodies were administrated to suppress the function of TGF-β. Cell proliferation and apoptosis were determined via Cell Counting Kit-8 and TUNEL assays, respectively. The results demonstrated that the overexpression of c-Jun robustly upregulated both mRNA and protein expression of TGF-β, TIMP metallopeptidase inhibitor 3, aggrecan and collagen type II alpha 1 chain and simultaneously downregulated the expression of the inflammatory cytokines TNF-α, interleukin (IL)-1β, IL-6 and IL-17. Furthermore, following c-Jun overexpression, survival rates of NP cells were increased while apoptosis rates were decreased. However, the addition of a TGF-β antibody significantly promoted apoptosis and restricted cell survival, which differed from the results of the c-Jun overexpression group. The present study hypothesized therefore that c-Jun may positively regulate TGF-β expression within NP cells of IDD, which could promote the proliferation of IDD-NP cells and accelerate cell viability via reducing apoptosis and the inflammatory response.

AMOTL2 inhibits JUN Thr239 dephosphorylation by binding PPP2R2A to suppress the proliferation in non-small cell lung cancer cells

Protein phosphatase 2A (PP2A) complex comprises an extended family of intracellular protein serine/threonine phosphatases, that participate in different signaling transduction pathways. Different functions of PP2As are determined by the variety of regulatory subunits. In this study, CRISPR/Cas9-mediated loss-of-function screen revealed that PPP2R2A downregulation suppressed cell growth in NSCLC cells. AMOTL2 was identified and confirmed as a novel binding partner of PPP2R2A in NSCLC cells by mass spectrometry, CO-IP, GST pull-down and immunofluorescence. Upregulation of AMOTL2 also led to cell proliferation delay in human and mouse lung tumor cells. The proto-oncogene JUN is a key subunit of activator protein-1 (AP-1) transcription factor which plays crucial role in regulating tumorigenesis and its activity is negatively regulated by the phosphorylation at T239. Our results showed that either AMOTL2 upregulation or PPP2R2A downregulation led to great increase in JUN T239 phosphorylation. AMOTL2 bound PPP2R2A in cytoplasm, which reduced nuclear localization of PPP2R2A. In conclusion, AMOTL2 and PPP2R2A act respectively as negative and positive regulator of cell growth in NSCLC cells and function in the AMOTL2-PPP2R2A-JUN axis, in which AMOTL2 inhibits the entry of PPP2R2A into the nucleus to dephosphorylate JUN at T239.

Parthenolide Inhibits Angiogenesis in Esophageal Squamous Cell Carcinoma Through Suppression of VEGF

Background

Parthenolide (PT), the effective active ingredient of the medicinal plant, feverfew (Tanacetum parthenium), has been used as an anti-inflammatory drug due to its involvement in the inhibition of the NF-кB pathway. Moreover, recent studies have demonstrated the anti-tumor effect of PT in several cancers. However, the effect of PT on esophageal carcinoma remains unclear to date. In this study, we examined the inhibitory effects of PT and its underlying mechanism of action in human esophageal squamous cell carcinoma (ESCC) cells – Eca109 and KYSE-510.

Methods

The proliferation ability of Eca109 and KYSE-510 treated with PT was detected using the Cell Counting Kit-8 and colony forming assay. The Transwell assay and the wound healing assay were used to analyze the cell invasion and migration ability, respectively. The tube formation assay was used to investigate the effect of PT on tube formation of endothelial cells. The expression level of NF-кB, AP-1 and VEGF was analyzed by Western blot.

Results

We demonstrated that PT attenuates the proliferation and migration ability of ESCC cells in vitro and also inhibits tumor growth in the mouse xenograft model. In addition, PT exhibited anti-angiogenesis activity by weakening the proliferation, invasion and tube formation of endothelial cells in vitro and reduced microvessel density in the xenograft tumors. Further studies revealed that PT reduced the expression level of NF-кB, AP-1 and VEGF in ESCC cells.

Conclusion

Collectively, the results of our study demonstrated that PT exerts anti-tumor and anti-angiogenesis effects possibly by inhibiting the NF-кB/AP-1/VEGF signaling pathway on esophageal carcinoma and might serve as a promising therapeutic agent for ESCC.

β-cantenin is potentially involved in the regulation of c-Jun signaling following bovine herpesvirus 1 infection

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BoHV-1 infection promotes nucleus accumulation of p-c-Jun(S73) and p-β-catenin(S552)

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The association between β-catenin and c-Jun in in nucleus is readily detected following BoHV-1 infection.

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BoHV-1 infection stimulates the expression and activation of c-Jun potentially through β-catenin.

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BoHV-1 infection leads to relocalization of nucleus c-Jun to form specific foci.

C-Jun, activated by various extracellular signals, is important for cell differentiation, proliferation, apoptosis, and inflammatory responses. We have previously reported that bovine herpesvirus 1 (BoHV-1) infection in MDBK cells stimulates the c-Jun NH2-terminal kinase (JNK)/c-Jun cascade for efficient replication. However, the mechanisms regarding the regulation of c-Jun following BoHV-1 infection remain unknown. In this study, we show that virus infection increases accumulation of p-c-Jun(S73) (phosphorylated c-Jun at Ser73) and p-β-catenin(S552) in the nucleus, resulting in relocalized nuclear p-c-Jun(S73) to assemble in highlighted punctum via a confocal microscope assay. An association between β-catenin and c-Jun in the nucleus was readily detected in virus-infected, but not mock-infected cells. Interestingly, β-catenin was found to be involved in the regulation of c-Jun signaling in virus-infected cells as iCRT14, a β-catenin-specific inhibitor that can inhibit β-catenin-dependent transcriptional activity, was able to decrease protein expression and phosphorylation of c-Jun. Furthermore, we suggest that BoHV-1 infection stimulates c-Jun phosphorylation regulated by β-catenin via both c-Jun NH2-terminal kinase (JNK)-dependent and JNK-independent mechanisms. These data add to our knowledge regarding the regulation of c-Jun following virus infection and further support the important roles of β-catenin signaling playing in BoHV-1 infection.

Suppression of LINC00460 mediated the sensitization of HCT116 cells to ionizing radiation by inhibiting epithelial-mesenchymal transition

Radiation resistance is the most common challenge for improving radiotherapy. The mechanisms underlying the development of radioresistance remain poorly understood. This study aims to explore the role of LINC00460 in ionizing radiation-induced radioresistance as well as the mechanisms by which LINC00460 is regulated by radiation exposure. The expression of LINC00460 was measured. Cell proliferation and colony formation were measured in HCT116 cells after treatment by radiation. The development of epithelial-mesenchymal transition (EMT) was determined with or without knockdown LINC00460 expression using western blot analysis. Transcription activity was determined using a series of LINC00460-promoter luciferase reporter gene vectors. LINC00460 expression was significantly higher in HCT116 cells, relative to other cell types, with LINC00460 expression significantly affecting HCT116 cell proliferation. Suppression of LINC00460 inhibits EMT development in HCT116 cells via regulation of ZEB1 expression. Furthermore, LINC00460 expression was induced by irradiation via the activation of c-jun transcription factor-binding element located on the LINC00460 promoter. LINC00460 was shown to play a crucial role in EMT-associated progression of colorectal cancer, indicating that LINC00460 may be an indicator or new potential therapeutic target for colorectal cancer radiosensitization.

The JNK Signaling Pathway in Inflammatory Skin Disorders and Cancer

The c-Jun N-terminal kinases (JNKs), with its members JNK1, JNK2, and JNK3, is a subfamily of (MAPK) mitogen-activated protein kinases. JNK signaling regulates a wide range of cellular processes, including cell proliferation, differentiation, survival, apoptosis, and inflammation. Dysregulation of JNK pathway is associated with a wide range of immune disorders and cancer. Our objective is to provide a review of JNK proteins and their upstream regulators and downstream effector molecules in common skin disorders, including psoriasis, dermal fibrosis, scleroderma, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.

Image-Based Analysis of Protein Stability

Short half-life proteins regulate many essential processes, including cell cycle, transcription, and apoptosis. However, few well-characterized protein-turnover pathways have been identified because traditional methods to measure protein half-life are time and labor intensive. To overcome this barrier, we developed a protein stability probe and high-content screening pipeline for novel regulators of short half-life proteins using automated image analysis. Our pilot probe consists of the short half-life protein c-MYC (MYC) fused to Venus fluorescent protein (MYC-Venus). This probe enables protein half-life to be scored as a function of fluorescence intensity and distribution. Rapid turnover prevents maximal fluorescence of the probe due to the relatively longer maturation time of the fluorescent protein. Cells expressing the MYC-Venus probe were analyzed using a pipeline in which automated confocal microscopy and image analyses were used to score MYC-Venus stability by two strategies: assaying the percentage of cells with Venus fluorescence above background, and phenotypic comparative analysis. To evaluate this high-content screening pipeline and our probe, a kinase inhibitor library was screened by confocal microscopy to identify known and novel kinases that regulate MYC stability. Compounds identified were shown to increase the half-life of both MYC-Venus and endogenous MYC, validating the probe and pipeline. Fusion of another short half-life protein, myeloid cell leukemia 1 (MCL1), with Venus also demonstrated an increase in percent Venus-positive cells after treatment with inhibitors known to stabilize MCL1. Together, the results validate the use of our automated microscopy and image analysis pipeline of stability probe-expressing cells to rapidly and quantitatively identify regulators of short half-life proteins. © 2019 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

Erk1/2 inactivation promotes a rapid redistribution of COP1 and degradation of COP1 substrates

Anthrax lethal toxin (LT) is a protease virulence factor produced by Bacillus anthracis that is required for its pathogenicity. LT treatment causes a rapid degradation of c-Jun protein that follows inactivation of the MEK1/2-Erk1/2 signaling pathway. Here we identify COP1 as the ubiquitin E3 ligase that is essential for LT-induced c-Jun degradation. COP1 knockdown using siRNA prevents degradation of c-Jun, ETV4, and ETV5 in cells treated with either LT or the MEK1/2 inhibitor, U0126. Immunofluorescence staining reveals that COP1 preferentially localizes to the nuclear envelope, but it is released from the nuclear envelope into the nucleoplasm following Erk1/2 inactivation. At baseline, COP1 attaches to the nuclear envelope via interaction with translocated promoter region (TPR), a component of the nuclear pore complex. Disruption of this COP1-TPR interaction, through Erk1/2 inactivation or TPR knockdown, leads to rapid COP1 release from the nuclear envelope into the nucleoplasm where it degrades COP1 substrates. COP1-mediated degradation of c-Jun protein, combined with LT-mediated blockade of the JNK1/2 signaling pathway, inhibits cellular proliferation. This effect on proliferation is reversed by COP1 knockdown and ectopic expression of an LT-resistant MKK7-4 fusion protein. Taken together, this study reveals that the nuclear envelope acts as a reservoir, maintaining COP1 poised for action. Upon Erk1/2 inactivation, COP1 is rapidly released from the nuclear envelope, promoting the degradation of its nuclear substrates, including c-Jun, a critical transcription factor that promotes cellular proliferation. This regulation allows mammalian cells to respond rapidly to changes in extracellular cues and mediates pathogenic mechanisms in disease states.

Coupling Computational and Intracellular Screening and Selection Toward Co-compatible cJun and cFos Antagonists

Basic leucine-zipper (bZIP) proteins represent difficult, yet compelling, oncogenic targets since numerous cell-signaling cascades converge upon them, where they function to modulate the transcription of specific gene targets. bZIPs are widely recognized as important regulators of cellular processes that include cell proliferation, apoptosis, and differentiation. Once such validated transcriptional regulator, activator protein-1, is typically composed of heterodimers of Fos and Jun family members, with cFos-cJun being the best described. It has been shown to be key in the progression and development of a number of different diseases. As a proof-of-principle for our approach, we describe the first use of a novel combined in silico/in cellulo peptide-library screening platform that facilitates the derivation of a sequence that displays high selectivity for cJun relative to cFos, while also avoiding homodimerization. In particular, >60 million peptides were computationally screened and all potential on/off targets ranked according to predicted stability, leading to a reduced size library that was further refined by intracellular selection. The derived sequence is predicted to have limited cross-talk with a second previously derived peptide antagonist that is selective for cFos in the presence of cJun. The study provides new insight into the use of multistate screening with the ability to combine computational and intracellular approaches in evolving multiple cocompatible peptides that are capable of satisfying conflicting design requirements.

Resveratrol attenuates diabetes-associated cell centrosome amplification via inhibiting the PKCα-p38 to c-myc/c-jun pathway

Type 2 diabetes increases the risk for cancer. Centrosome amplification can initiate tumorigenesis. We have described that type 2 diabetes increases the centrosome amplification of peripheral blood mononuclear cells, with high glucose, insulin, and palmitic acid as the triggers, which suggests that centrosome amplification is a candidate biological mechanism linking diabetes to cancer. In this study, we aimed to further investigate the signaling pathways of the diabetes-associated centrosome amplification and to examine whether and how resveratrol inhibits the centrosome amplification. The results showed that treatment with high glucose, insulin, and palmitic acid, alone or in combination, could increase the protein levels of phospho-protein kinase C alpha (p-PKCα), phospho-p38 mitogen-activated protein kinases (p-p38), c-myc, and c-jun, as well as the mRNA levels of c-myc and c-jun. PKCα inhibitor could inhibit the treatment-induced increase in the protein levels of p-p38, c-myc, and c-jun. Inhibitor or siRNA of p38 was also able to inhibit the treatment-induced increase in the levels of p-p38, c-myc, and c-jun. Meanwhile, knockdown of c-myc or c-jun did not alter the treatment-induced increase in the phosphorylation of PKCα or p38. Importantly, inhibition of the phosphorylation of PKCα or p38 and knockdown of c-myc or c-jun could attenuate the centrosome amplification. In diabetic mice, the levels of p-PKCα, p-p38, c-myc, and c-jun were all increased in the colon tissues. Interestingly, resveratrol, but not metformin, was able to attenuate the treatment-induced increase in the levels of p-PKCα, p-p38, c-myc, and c-jun, as well as the centrosome amplification. In conclusion, our results suggest that PKCα-p38 to c-myc/c-jun is the signaling pathway of the diabetes-associated centrosome amplification, and resveratrol attenuates the centrosome amplification by inhibiting this signaling pathway.

The AP-1 pathway; A key regulator of cellular transformation modulated by oncogenic viruses

Cancer progression is critically associated with modulation of host cell signaling pathways. Activator protein-1 (AP-1) signaling is one such pathway whose deregulation renders the host more susceptible to cancer development. Oncogenic viruses, including hepatitis B virus, hepatitis C virus, human papilloma virus, Epstein-Barr virus, human T-cell lymphotropic virus type 1, and Kaposi's sarcoma-associated herpes virus, are common causes of cancer. This review discusses how these oncoviruses by acting through various aspects of the host cell signaling machinery such as the AP-1 pathway might affect oncoviral tumorigenesis, replication, and pathogenesis. The review also briefly considers how the pathway might be targeted during infections with these oncogenic viruses.

Capn4 is induced by and required for Epstein-Barr virus latent membrane protein 1 promotion of nasopharyngeal carcinoma metastasis through ERK/AP-1 signaling

Capn4, also known as CapnS1, is a member of the calpain family, which plays a crucial role in maintaining the activity and function of calpain. We previously reported that Capn4 also plays an essential role in the migration of nasopharyngeal carcinoma (NPC) cells through regulation of (MMP‐2) by nuclear factor‐kappa B activation. Epstein‐Barr virus latent membrane protein 1 (LMP1) is closely related to the malignant functions of NPC; however, the relationship between LMP1 and Capn4 in NPC remain unclear. Immunohistochemical studies showed that the level of LMP1 and Capn4 expression was high in both primary and metastatic NPC tissues, with a significantly positive correlation. We further found that LMP1 was able to upregulate the Capn4 promoter in a dose‐dependent way through the C‐terminal activation region (CTAR)1 and CTAR2 domains to activate AP‐1. Moreover, we also found that LMP1 activated AP‐1 through ERK/JNK phosphorylation. These findings indicate that Capn4 coordination with LMP1 promotes actin rearrangement and, ultimately, cellular migration. These results show that Capn4 coordination with LMP1 enhances NPC migration by increasing actin rearrangement involving ERK/JNK/AP‐1 signaling. Therapeutically, additional and more specific LMP1 and Capn4 targeted inhibitors could be exploited to treat NPC.