Role of JNK in mammary gland development and breast cancer

The Role of the Dysregulated JNK Signaling Pathway in the Pathogenesis of Human Diseases and Its Potential Therapeutic Strategies: A Comprehensive Review

JNK is named after c-Jun N-terminal kinase, as it is responsible for phosphorylating c-Jun. As a member of the mitogen-activated protein kinase (MAPK) family, JNK is also known as stress-activated kinase (SAPK) because it can be activated by extracellular stresses including growth factor, UV irradiation, and virus infection. Functionally, JNK regulates various cell behaviors such as cell differentiation, proliferation, survival, and metabolic reprogramming. Dysregulated JNK signaling contributes to several types of human diseases. Although the role of the JNK pathway in a single disease has been summarized in several previous publications, a comprehensive review of its role in multiple kinds of human diseases is missing. In this review, we begin by introducing the landmark discoveries, structures, tissue expression, and activation mechanisms of the JNK pathway. Next, we come to the focus of this work: a comprehensive summary of the role of the deregulated JNK pathway in multiple kinds of diseases. Beyond that, we also discuss the current strategies for targeting the JNK pathway for therapeutic intervention and summarize the application of JNK inhibitors as well as several challenges now faced. We expect that this review can provide a more comprehensive insight into the critical role of the JNK pathway in the pathogenesis of human diseases and hope that it also provides important clues for ameliorating disease conditions.

HPV16 E7 protein antagonizes TNF-α-induced apoptosis of cervical cancer cells via Daxx/JNK pathway

Human papillomavirus (HPV) E7 protein as an important viral factor was involved in the progression of cervical cancer by mediating the cellular signaling pathways. Daxx (Death domain-associated protein) can interact with a variety of proteins to affect the viral infection process. However, the interaction and its related function between HPV16 E7 and Daxx have not been adequately investigated. Here, it was found that HPV16 E7 can interact with Daxx in HeLa or C33A cells by co-immunoprecipitation. HPV16 E7 protein treatment can up-regulate Daxx protein expression, while the interference in Daxx expression and the agonists for JNK can both reduce the antagonistic effects of HPV16 E7 on TNF-α-induced apoptosis, suggesting that Daxx/JNK pathway may be involved in the anti-apoptotic activity of HPV16 E7.

Depleting ANTXR1 suppresses glioma growth via deactivating PI3K/AKT pathway

Gliomas are commonly known as primary brain tumors and associated with frequent recurrence and an unsatisfactory prognosis despite extensive research in the underlying molecular mechanisms. We aimed to examine the role of ANTXR1 in glioma tumorigenesis and explore its downstream regulatory mechanism. ANTXR1 expression in clinical specimens and its relationship with some pathological characteristics were detected using immunohistochemical staining. After silencing/upregulating ANTXR1 through lentiviral transfection in glioma cell lines, qRT-PCR and western blotting were used to examine mRNA and protein levels, and cell phenotype was also detected. ANTXR1-knockdown and -overexpression cells were then processed by AKT activator and PI3K inhibitor, respectively, to verify downstream PI3K/AKT pathway regulated by ANTXR1. Xenograft nude mice models were constructed to verify the role of ANTXR1 in vivo. We found overexpression of ANTXR1 in both cell lines in comparison with those in normal brain tissues. Glioma cell growth and migratory ability were dramatically impaired as a result of silencing ANTXR1 by shANTXR1 lentiviruses. ANTXR1 blockade also accelerated cell apoptosis and held back cell cycle via targeting G2 phrase during cell mitosis. In vivo xenograft models verified in vitro findings above. Further exploration disclosed that AKT activator promoted anti-tumor effects mediated by ANTXR1 knockdown, while PI3K inhibitor limited pro-tumor effects mediated by ANTXR1 overexpression, indicating that ANTXR1 functioned in glioma cells through regulating PI3K/AKT pathway. ANTXR1 could play an indispensable role in glioma tumorigenesis via activating PI3K/AKT-mediated cell growth. Our study provides a theoretical basis for targeting ANTXR1 as a molecular target in glioma clinical therapeutics.

Valproic acid inhibits cell growth in both MCF-7 and MDA-MB231 cells by triggering different responses in a cell type-specific manner

BACKGROUND

Breast cancer is the second leading cause of death among women after lung cancer. Despite the improvement in prevention and in therapy, breast cancer still remains a threat, both for pre- and postmenopausal women, due to the development of drug resistance. To counteract that, novel agents regulating gene expression have been studied in both hematologic and solid tumors. The Histone Deacetylase (HDAC) inhibitor Valproic Acid (VA), used for epilepsy and other neuropsychiatric diseases, has been demonstrated a strong antitumoral and cytostatic activity. In this study, we tested the effects of Valproic Acid on the signaling pathways involved in breast cancer cells viability, apoptosis and in Reactive Oxygen Species (ROS) production using ER-α positive MCF-7 and triple negative MDA-MB-231 cells.

METHODS

Cell proliferation assay was performed by MTT Cell cycle, ROS levels and apoptosis were analyzed by flow cytometry, protein levels were detected by Western Blotting.

RESULTS

Cell treatment with Valproic Acid reduced cell proliferation and induced G0/G1 cell cycle arrest in MCF-7 and G2/M block in MDA-MB-231 cells. In addition, in both cells the drug enhanced the generation of ROS by the mitochondria. In MCF-7 treated cells, it has been observed a reduction in mitochondrial membrane potential, a down regulation of the anti-apoptotic marker Bcl-2 and an increase of Bax and Bad, leading to release of cytochrome C and PARP cleavage. Less consistent effects are recorded in MDA-MB-231 cells, in which the greater production of ROS, compared to MCF-7cells, involves an inflammatory response (activation of p-STAT3, increased levels of COX2).

CONCLUSIONS

Our results have demonstrated that in MCF-7 cells the Valproic Acid is a suitable drug to arrest cell growth, to address apoptosis and mitochondrial perturbations, all factors that are important in determining cell fate and health. In a triple negative MDA-MB 231 cells, valproate directs the cells towards the inflammatory response with a sustained expression of antioxidant enzymes. Overall, the not always unequivocal data between the two cellular phenotypes indicate that further studies are needed to better define the use of the drug, also in combination with other chemotherapy, in the treatment of breast tumors.

HER2-driven breast cancer suppression by the JNK signaling pathway

The HER2⁺ subtype of human breast cancer is associated with the malignant transformation of luminal ductal cells of the mammary epithelium. The sequence analysis of tumor DNA identifies loss of function mutations and deletions of the MAP2K4 and MAP2K7 genes that encode direct activators of the JUN NH₂-terminal kinase (JNK). We report that in vitro studies of human mammary epithelial cells with CRISPR-induced mutations in the MAPK and MAP2K components of the JNK pathway caused no change in growth in 2D culture, but these mutations promoted epithelial cell proliferation in 3D culture. Analysis of gene expression signatures in 3D culture demonstrated similar changes caused by HER2 activation and JNK pathway loss. The mechanism of signal transduction cross-talk may be mediated, in part, by JNK-suppressed expression of integrin α6β4 that binds HER2 and amplifies HER2 signaling. These data suggest that HER2 activation and JNK pathway loss may synergize to promote breast cancer. To test this hypothesis, we performed in vivo studies using a mouse model of HER2⁺ breast cancer with Cre/loxP-mediated ablation of genes encoding JNK (Mapk8 and Mapk9) and the MAP2K (Map2k4 and Map2k7) that activate JNK in mammary epithelial cells. Kaplan-Meier analysis of tumor development demonstrated that JNK pathway deficiency promotes HER2⁺-driven breast cancer. Collectively, these data identify JNK pathway genes as potential suppressors for HER2⁺ breast cancer.

Identification of selection signatures in Capra hircus and Capra aegagrus in Iran

Identification of selection signatures may provide a better understanding of domestication process and candidate genes contributing to this process. In this study, two populations of domestic and wild goats from Iran were analyzed to identify selection signatures. RSB, iHS, and XP-EHH statistics were used in order to identify robust selection signatures in the goat genome. Genotype data of domestic and wild goats from the NextGen project was used. The data was related to 18 Capra aegagrus (wild goat) and 20 Capra hircus (domestic goat) from Iran. The iHS method indicated 675 and 441 selection signatures in C. aegagrus and C. hircus, respectively. RSB and XP-EHH methods showed about 370 and 447 selection signatures in C. aegagrus and C. hircus, respectively. These selection signatures were mainly associated with milk production, fleece trait, mammary epithelial cells, reproduction, and immune system.

Non-kinase targeting of oncogenic c-Jun N-terminal kinase (JNK) signaling: the future of clinically viable cancer treatments

c-Jun N-terminal Kinases (JNKs) have been identified as key disease drivers in a number of pathophysiological settings and central oncogenic signaling nodes in various cancers. Their roles in driving primary tumor growth, positively regulating cancer stem cell populations, promoting invasion and facilitating metastatic outgrowth have led JNKs to be considered attractive targets for anti-cancer therapies. However, the homeostatic, apoptotic and tumor-suppressive activities of JNK proteins limit the use of direct JNK inhibitors in a clinical setting. In this review, we will provide an overview of the different JNK targeting strategies developed to date, which include various ATP-competitive, non-kinase and substrate-competitive inhibitors. We aim to summarize their distinct mechanisms of action, review some of the insights they have provided regarding JNK-targeting in cancer, and outline the limitations as well as challenges of all strategies that target JNKs directly. Furthermore, we will highlight alternate drug targets within JNK signaling complexes, including recently identified scaffold proteins, and discuss how these findings may open up novel therapeutic options for targeting discrete oncogenic JNK signaling complexes in specific cancer settings.

DUSP4 Silencing Enhances the Sensitivity of Breast Cancer Cells to Doxorubicin through the Activation of the JNK/c-Jun Signalling Pathway

Doxorubicin (Dox) has limited efficiency in breast cancer (BC) due to drug-acquired resistance. The epithelial–mesenchymal transition (EMT) plays a major role in the survival and drug resistance of cancer cells. It was suggested that the JNK pathway was implicated in the response to Dox by regulating EMT. DUSP4/or MKP-2 is a well-known regulator of the JNK pathway and was found to be highly expressed in BC. However, its functional significance is not yet fully understood. In the present study, the possible involvement of MKP-2 in Dox-induced EMT was investigated in breast cancer cells. Immunohistochemistry for tissues obtained from BC patients (n = 108) revealed 71.3% of tissues stained positively for MKP-2 while only 28.7% stained negatively. However, MKP-2 protein expression exhibited no significant relationship between BC prognostic factors, such as histological grade, histological type, hormonal status, and Ki-67 marker, its expression was significantly correlated with age 40 or below. In MDA-MB-231 cells, Dox-induced phosphorylation of JNK was sufficiently enhanced in MKP-2 silenced cells. This resulted in the attenuation of Dox-induced EMT, cell cycle arrest, and ultimately accelerated apoptosis. It was confirmed that the acquisition of Dox sensitivity by MKP-2 silencing largely depends on the stimulation of the JNK pathway. Indeed, results showed that overexpressing MKP-2 in non-tumorigenic MCF-12A cells dramatically inhibited Dox-induced JNK activation and, subsequently, cell death. The present study, to our knowledge, is the first to provide evidence for the potential role of MKP-2 in chemoresistance to Dox through modulating the JNK pathway and enhancing EMT.

The potential application of organoids in breast cancer research and treatment

Tumor heterogeneity is a major challenge for breast cancer researchers who have struggled to find effective treatments despite recent advances in oncology. Although the use of 2D cell culture methods in breast cancer research has been effective, it cannot model the heterogeneity of breast cancer as found within the body. The development of 3D culture of tumor cells and breast cancer organoids has provided a new approach in breast cancer research, allowing the identification of biomarkers, study of the interaction of tumor cells with the microenvironment, and for drug screening and discovery. In addition, the possibility of gene editing in organoids, especially using the CRISPR/Cas9 system, is convenient, and has allowed a more detailed study of tumor behavior in models closer to the physiological condition. The present review covers the application of organoids in breast cancer research. The recent use of gene-editing systems to provide insights into therapeutic approaches for breast cancer, is highlighted. The study of organoids and the possibility of gene manipulation may be a step towards the personalized treatment of breast cancer, which has so far remained unattainable due to the high heterogeneity of breast cancer.

Disruption of Jmjd3/p16Ink4a Signaling Pathway Causes Bizarre Parosteal Osteochondromatous Proliferation (BPOP)-like Lesion in Mice

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare benign osteochondromatous lesion. At present, the molecular etiology of BPOP remains unclear. JMJD3(KDM6B) is an H3K27me3 demethylase and counteracts polycomb-mediated transcription repression. Previously, Jmjd3 was shown to be critical for bone development and osteoarthritis. Here, we report that conditional deletion of Jmjd3 in chondrogenic cells unexpectedly resulted in BPOP-like lesion in mice. Biochemical investigations revealed that Jmjd3 inhibited BPOP-like lesion through p16^Ink4a . Immunohistochemistry and RT-qPCR assays indicated JMJD3 and p16^INK4A level were significantly reduced in human BPOP lesion compared with normal subjects. This was further confirmed by Jmjd3/Ink4a double-gene knockout mice experiments. Therefore, our results indicated the pathway of Jmjd3/p16^Ink4a may be essential for the development of BPOP in human. © 2021 American Society for Bone and Mineral Research (ASBMR).

JunD, not c-Jun, is the AP-1 transcription factor required for Ras-induced lung cancer

The AP-1 transcription factor c-Jun is required for Ras-driven tumorigenesis in many tissues and is considered as a classical proto-oncogene. To determine the requirement for c-Jun in a mouse model of K-RasG12D-induced lung adenocarcinoma, we inducibly deleted c-Jun in the adult lung. Surprisingly, we found that inactivation of c-Jun, or mutation of its JNK phosphorylation sites, actually increased lung tumor burden. Mechanistically, we found that protein levels of the Jun family member JunD were increased in the absence of c-Jun. In c-Jun-deficient cells, JunD phosphorylation was increased, and expression of a dominant-active JNKK2-JNK1 transgene further increased lung tumor formation. Strikingly, deletion of JunD completely abolished Ras-driven lung tumorigenesis. This work identifies JunD, not c-Jun, as the crucial substrate of JNK signaling and oncogene required for Ras-induced lung cancer.

Silencing of LRRFIP1 enhances the sensitivity of gemcitabine in pancreatic cancer cells by activating JNK/c-Jun signaling

BACKGROUND

The epithelial-mesenchymal transition (EMT) in cancer cells has been shown to closely associate with the survival and drug resistance of cancer cells. We recently provided evidence that Wnt signal activator leucine-rich repeat in flightless-1-interacting protein 1 (LRRFIP1) regulates EMT in pancreatic cancer. LRRFIP1 silencing inhibits the translocation of β-catenin to the nucleus, which led to reverse EMT in cancer cells. It was suggested that LRRFIP1 was implicated in gemcitabine sensitivity by regulating EMT signaling.

METHODS

Gemcitabine chemosensitivity was investigated in LRRFIP1-knockdown pancreatic cancer cells (PANC-1 and MIA Paca-2). In addition, the effects of LRRFIP1 knockdown on JNK/SAPK (stress activated-protein kinase) signaling and apoptosis were evaluated.

RESULTS

LRRFIP1 silencing accelerates gemcitabine-induced caspase activity and cell death in pancreatic cancer cells. It was also revealed that gemcitabine-induced phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun were increased in LRRFIP1 knockdown cells. The activation of JNK/c-Jun in LRRFIP1-knockdown cells was significantly diminished by the inhibition of Rac activity. It was confirmed that the acquisition of gemcitabine sensitivity by LRRFIP1 silencing largely depends on the stimulation of JNK/SAPK (stress activated-protein kinase) signaling.

CONCLUSIONS

Our findings suggest that reversing EMT and transient activation of JNK might be essential for the gemcitabine sensitivity in LRRFIP1 knockdown pancreatic cancer cells. Our discoveries highlight the potential role of LRRFIP1 in the chemosensitivity related to the regulation of EMT signaling.

Triangle collaboration assessment of autophagy, ER stress and hypoxia in leukemogenesis: a bright perspective on the molecular recognition of B-ALL

B-lineage acute lymphoblastic leukemia (B-ALL) is the most common acute leukemia in childhood and adults, which caused by many various crystalline and unclear agents. Owning to this matter, no significant progress has been made in the patients-recovery. Recently, autophagy pathway is considered as an ambiguous agent in leukemia evaluation. We aim to discover the expression levels of upstream autophagy-regulating genes in newly diagnosed B-ALL patients. In B-ALL group, BECN1, HIF1A and ERN1 expressions were significantly down-regulated, while BCL2 expression was up-regulated compared to the control group (p < .05). Moreover, there was significant positive correlation between the decreased BECN1 compared with Hypoxia and endoplasmic reticulum (ER) stress-related genes expression in the patients (p < .05). Our findings revealed that, ERN1 and ER stress pathway-related genes could be effective regulators of autophagy in B-ALL. More investigation is recommended to gain a deeper understanding into molecular pathophysiology of B-ALL to improve treatment and monitoring approaches in affected patients.

JNK in Tumor Microenvironment: Present Findings and Challenges in Clinical Translation

Simple Summary

Stress-activated c-Jun N-terminal kinases (JNKs) are members of mitogen-activated protein kinases (MAPKs). Apart from having both tumor promoting and tumor suppressing roles in cancers due to its impact on apoptosis and autophagy pathways, JNK also plays complex roles in the heterogeneous tumor microenvironment (TME) and is involved in different tumorigenesis pathways. The JNK pathway influences various stressful and chronic inflammatory conditions along with different cell populations in TME. In this review, we aim to present the current knowledge of JNK-mediated processes in TME and the challenges in clinical translation.

Abstract

The c-Jun N-terminal kinases (JNKs) are a group of mitogen-activated protein kinases (MAPKs). JNK is mainly activated under stressful conditions or by inflammatory cytokines and has multiple downstream targets for mediating cell proliferation, differentiation, survival, apoptosis, and immune responses. JNK has been demonstrated to have both tumor promoting and tumor suppressing roles in different cancers depending on the focused pathway in each study. JNK also plays complex roles in the heterogeneous tumor microenvironment (TME). JNK is involved in different tumorigenesis pathways. TME closely relates with tumor development and consists of various stressful and chronic inflammatory conditions along with different cell populations, in which the JNK pathway may have various mediating roles. In this review, we aim to summarize the present knowledge of JNK-mediated processes in TME, including hypoxia, reactive oxygen species, inflammation, immune responses, angiogenesis, as well as the regulation of various cell populations within TME. This review also suggests future research directions for translating JNK modulation in pre-clinical findings to clinical benefits.

Pathophysiological Significance of WDR62 and JNK Signaling in Human Diseases

The c-Jun N-terminal kinase (JNK) is highly evolutionarily conserved and plays important roles in a broad range of physiological and pathological processes. The WD40-repeat protein 62 (WDR62) is a scaffold protein that recruits different components of the JNK signaling pathway to regulate several human diseases including neurological disorders, infertility, and tumorigenesis. Recent studies revealed that WDR62 regulates the process of neural stem cell mitosis and germ cell meiosis through JNK signaling. In this review we summarize the roles of WDR62 and JNK signaling in neuronal and non-neuronal contexts and discuss how JNK-dependent signaling regulates both processes. WDR62 is involved in various human disorders via JNK signaling regulation, and may represent a promising therapeutic strategy for the treatment of related diseases.

JNK signaling as a target for anticancer therapy

The JNKs are members of mitogen-activated protein kinases (MAPK) which regulate many physiological processes including inflammatory responses, macrophages, cell proliferation, differentiation, survival, and death. It is increasingly clear that the continuous activation of JNKs has a role in cancer development and progression. Therefore, JNKs represent attractive oncogenic targets for cancer therapy using small molecule kinase inhibitors. Studies showed that the two major JNK proteins JNK1 and JNK2 have opposite functions in different types of cancers, which need more specification in the design of JNK inhibitors. Some of ATP- competitive and ATP non-competitive inhibitors have been developed and widely used in vitro, but this type of inhibitors lack selectivity and inhibits phosphorylation of all JNK substrates and may lead to cellular toxicity. In this review, we summarized and discussed the strategies of JNK binding inhibitors and the role of JNK signaling in the pathogenesis of different solid and hematological malignancies.

The Prognostic Significance of Anisomycin-Activated Phospho-c-Jun NH2-Terminal Kinase (p-JNK) in Predicting Breast Cancer Patients' Survival Time

This study aims to investigate the prognostic significance of p-JNK in breast cancer patients receiving neoadjuvant chemotherapy (NACT) and analyze the relationship between anisomycin, p-JNK. A total of 104 breast cancer patients had NACT were enrolled in this study. The western blot and immunohistochemistry assays were used to determine the protein expressions of p-JNK in human breast cancer cell lines and patients’ cancer tissues. The chi-square test and Fisher’s exact test were adopted to gauge the associations between breast cancer and clinicopathological variables by p-JNK expression, whereas the univariate and multivariate Cox proportional hazards regression models were used to analyze the prognostic value of p-JNK expression. The Kaplan-Meier plots and the log-rank test were adopted to determine patients’ disease-free survival (DFS) and overall survival (OS). Findings indicated that the p-JNK expression had prognostic significance in univariate and multivariate Cox regression survival analyses. Results of log-rank methods showed that: (1) the mean DFS and OS times in patients with high p-JNK expression were significantly longer than those in patients with low p-JNK expression (χ² = 5.908, P = 0.015 and χ² = 6.593, P = 0.010, respectively). p-JNK expression is a significant prognostic factor that can effectively predict the survival in breast cancer patients receiving NACT. Treatment with the JNK agonist anisomycin can induce apoptosis, lead to increased p-JNK expression and decreased p-STAT3 expression. Moreover, the p-JNK expression was inversely correlated with p-STAT3 expression.

JNK3 as Therapeutic Target and Biomarker in Neurodegenerative and Neurodevelopmental Brain Diseases

The c-Jun N-terminal kinase 3 (JNK3) is the JNK isoform mainly expressed in the brain. It is the most responsive to many stress stimuli in the central nervous system from ischemia to Aβ oligomers toxicity. JNK3 activity is spatial and temporal organized by its scaffold protein, in particular JIP-1 and β-arrestin-2, which play a crucial role in regulating different cellular functions in different cellular districts. Extensive evidence has highlighted the possibility of exploiting these adaptors to interfere with JNK3 signaling in order to block its action. JNK plays a key role in the first neurodegenerative event, the perturbation of physiological synapse structure and function, known as synaptic dysfunction. Importantly, this is a common mechanism in many different brain pathologies. Synaptic dysfunction and spine loss have been reported to be pharmacologically reversible, opening new therapeutic directions in brain diseases. Being JNK3-detectable at the peripheral level, it could be used as a disease biomarker with the ultimate aim of allowing an early diagnosis of neurodegenerative and neurodevelopment diseases in a still prodromal phase.

Activation of JNK and p38 in MCF-7 Cells and the In Vitro Anticancer Activity of Alnus hirsuta Extract

JNK and p38 are important mitogen-activated protein kinases (MAPKs) that respond to stress stimuli. The stress-activated MAPKs associated with apoptotic cell death play vital roles in mammalian cells. Alnus hirsuta, which contains abundant diarylheptanoids derivatives, is a valuable medicinal plant. The CHCl3 extract (AHC) containing platyphyllenone (1) and platyphyllone (3) as main compounds showed in vitro anticancer effects. We report the biological activities of A. hirsuta extract associated with the regulation of apoptosis and JNK and p38 in MCF-7 breast cancer cells. Levels of phospho-JNK and phospho-p38 by AHC treatment were evaluated by enzyme-linked immunosorbent assay (ELISA). ROS production, apoptotic effect, and DNA contents of the cells were measured by flow cytometry. The two diarylheptanoids 1 and 3 and the AHC extract exhibited cytotoxic effects on MCF-7 cells in MTT assay, with IC50 values of 18.1, 46.9, 260.0 μg/mL, respectively. AHC induced ROS generation and elevated the endogenous levels of phospho-JNK and phospho-p38. AHC resulted in apoptosis and cell cycle arrest. We suggest that the antitumor effect of A. hirsuta extract is achieved by apoptosis promotion and cell cycle arrest mediated by the activation of JNK and p38 signaling pathway via ROS generation.

JNK-Dependent cJun Phosphorylation Mitigates TGFβ- and EGF-Induced Pre-Malignant Breast Cancer Cell Invasion by Suppressing AP-1-Mediated Transcriptional Responses

Transforming growth factor-β (TGFβ) has both tumor-suppressive and tumor-promoting effects in breast cancer. These functions are partly mediated through Smads, intracellular transcriptional effectors of TGFβ. Smads form complexes with other DNA-binding transcription factors to elicit cell-type-dependent responses. Previously, we found that the collagen invasion and migration of pre-malignant breast cancer cells in response to TGFβ and epidermal growth factor (EGF) critically depend on multiple Jun and Fos components of the activator protein (AP)-1 transcription factor complex. Here we report that the same process is negatively regulated by Jun N-terminal kinase (JNK)-dependent cJun phosphorylation. This was demonstrated by analysis of phospho-deficient, phospho-mimicking, and dimer-specific cJun mutants, and experiments employing a mutant version of the phosphatase MKP1 that specifically inhibits JNK. Hyper-phosphorylation of cJun by JNK strongly inhibited its ability to induce several Jun/Fos-regulated genes and to promote migration and invasion. These results show that MEK-AP-1 and JNK-phospho-cJun exhibit distinct pro- and anti-invasive functions, respectively, through differential regulation of Smad- and AP-1-dependent TGFβ target genes. Our findings are of importance for personalized cancer therapy, such as for patients suffering from specific types of breast tumors with activated EGF receptor-Ras or inactivated JNK pathways.

SHARPIN overexpression promotes TAK1 expression and activates JNKs and NF-κB pathway in Mycosis Fungoides

Mycosis Fungoides (MF) is the most common subtype of cutaneous T-cell lymphomas (CTCL). Shank-associated RH domain-interacting protein (SHARPIN) participates in the initiation and development of multiple tumors. However, the clinical significance of SHARPIN in MF hasn't been investigated. The c-Jun N-terminal kinases (JNKs) pathway is a member of mitogen-activated protein kinases (MAPKs). Its dysregulation is observed in various tumors including CTCL, whereas the roles of JNKs pathway in MF remain largely unknown, the relationship between SHARPIN and JNKs pathway remains elusive. Herein, we showed that upregulated expression of SHARPIN was related to poor prognosis of MF patients. In vitro experiments found increased SHARPIN expression and activation of JNKs pathway in MF cell line MyLa2059. SHARPIN induced transforming growth factor β activated kinase-1 (TAK1) transcription, which is an upstream kinase of JNKs, NF-κB and p38 pathway, leading to activation of JNKs and NF-κB pathway. SHARPIN also promoted p38 signalling independent of TAK1 expression, by which overexpression of SHARPIN induced cell proliferation, inhibited apoptosis, enhanced migration and invasion of MyLa2059. Our work provided direct evidences for effects of SHARPIN on JNKs and NF-κB pathway, and the contributing roles of JNKs, NF-κB and p38 pathway regulated by SHARPIN in the development of MF.

JNK2 Is Required for the Tumorigenic Properties of Melanoma Cells

Overexpression and activation of c-Jun N-terminal kinases (JNKs) have been observed in multiple cancer cell lines and tumor samples. Various JNK isoforms have been reported to promote lung and liver cancer, as well as keratinocyte transformation, suggesting an important role of JNK signaling in promoting tumor development. However, there are three JNK isoforms, and it is unclear how each individual isoform, especially the ubiquitously expressed JNK1 and JNK2, functions in melanoma. Our previous study found that C116S mutations in both JNK1 and JNK2 rendered them insensitive to the covalent pan-JNK inhibitor JNK-IN-8 while retaining kinase activity. To delineate the specific roles of JNK1 and JNK2 in melanoma cell proliferation and invasiveness, we expressed the wild type (WT) and C116S mutants in melanoma cell lines and used JNK-IN-8 to enable chemical-genetic dissection of JNK1 and JNK2 activity. We found that the JNK2^C116S allele consistently enhanced colony proliferation and cell invasiveness in the presence of JNK-IN-8. When cells individually expressing WT or C116S JNK1/2 were subcutaneously implanted into immunodeficient mice, we again found that bypass of JNK-IN-8-mediated inhibition of JNK signaling by expression of JNK2^C116S specifically resulted in enhanced tumor growth in vivo. In addition, we observed a high level of JNK pathway activation in some human BRAF inhibitor (BRAFi) resistant melanoma cell lines relative to their BRAFi sensitive isogenic counterparts. JNK-IN-8 significantly enhanced the response to dabrafenib in resistant cells overexpressing JNK1^WT, JNK2^WT, and JNK1^C116S but had no effect on cells expressing JNK2^C116S, suggesting that JNK2 signaling is also crucial for BRAFi resistance in a subset of melanomas. Collectively, our data show that JNK2 activity is specifically required for melanoma cell proliferation, invasiveness, and BRAFi resistance and that this activity is most important in the context of JNK1 suppression, thus providing a compelling rationale for the development of JNK2 selective inhibitors as a potential therapy for the treatment of melanoma.

Inhibition of Gap Junctions Sensitizes Primary Glioblastoma Cells for Temozolomide

Gap junctions have recently been shown to interconnect glioblastoma cells to a multicellular syncytial network, thereby allowing intercellular communication over long distances as well as enabling glioblastoma cells to form routes for brain microinvasion. Against this backdrop gap junction-targeted therapies might provide for an essential contribution to isolate cancer cells within the brain, thus increasing the tumor cells’ vulnerability to the standard chemotherapeutic agent temozolomide. By utilizing INI-0602—a novel gap junction inhibitor optimized for crossing the blood brain barrier—in an oncological setting, the present study was aimed at evaluating the potential of gap junction-targeted therapy on primary human glioblastoma cell populations. Pharmacological inhibition of gap junctions profoundly sensitized primary glioblastoma cells to temozolomide-mediated cell death. On the molecular level, gap junction inhibition was associated with elevated activity of the JNK signaling pathway. With the use of a novel gap junction inhibitor capable of crossing the blood–brain barrier—thus constituting an auspicious drug for clinical applicability—these results may constitute a promising new therapeutic strategy in the field of current translational glioblastoma research.

An integrated stress response via PKR suppresses HER2+ cancers and improves trastuzumab therapy

Trastuzumab is integral to HER2+ cancer treatment, but its therapeutic index is narrowed by the development of resistance. Phosphorylation of the translation initiation factor eIF2α (eIF2α-P) is the nodal point of the integrated stress response, which promotes survival or death in a context-dependent manner. Here, we show an anti-tumor function of the protein kinase PKR and its substrate eIF2α in a mouse HER2+ breast cancer model. The anti-tumor function depends on the transcription factor ATF4, which upregulates the CDK inhibitor P21^CIP1 and activates JNK1/2. The PKR/eIF2α-P arm is induced by Trastuzumab in sensitive but not resistant HER2+ breast tumors. Also, eIF2α-P stimulation by the phosphatase inhibitor SAL003 substantially increases Trastuzumab potency in resistant HER2+ breast and gastric tumors. Increased eIF2α-P prognosticates a better response of HER2+ metastatic breast cancer patients to Trastuzumab therapy. Hence, the PKR/eIF2α-P arm antagonizes HER2 tumorigenesis whereas its pharmacological stimulation improves the efficacy of Trastuzumab therapy.

The HER2 monoclonal antibody, Trastuzumab, is the current standard treatment for HER2+ cancers but resistance to therapy occurs. Here, the authors show that activation of the PKR/eIF2α-P pathway exhibits anti-tumor effects in HER2+ cancer and is required for the response to Trastuzumab.

Ochratoxin A mediates cytotoxicity through the MAPK signaling pathway and alters intracellular homeostasis in bovine mammary epithelial cells

Ochratoxin A (OTA), a secondary metabolite of the genera Penicillium and Aspergillus, contaminates many types of food and causes apoptosis as well as immunosuppression in many animal species. However, a mechanistic analysis of OTA-mediated cytotoxicity in bovine mammary epithelial cells has not yet been performed. Hence, we investigated the effects of OTA on bovine mammary epithelial (MAC-T) cells using several mechanistic analyses. We report that OTA may induce cell cycle arrest and apoptosis via MAPK and JNK signaling pathways in MAC-T cells. Moreover, homeostasis of cellular components, such as that of the mitochondrial membrane, was disrupted by OTA, leading to a decrease in mitochondrial and cytosolic Ca²⁺ in MAC-T cells. In addition, we evaluated the effects of OTA on inflammatory responses and major tight junction regulators, such as occludin and claudin 3. In summation, we suggest that OTA contamination may adversely affect bovine mammary epithelial cells, leading to improper lactation and decreased milk quality. This article aims to improve the understanding of physiological mechanisms involved in lactation, in addition to providing a guideline for the stabilization of industrial milk production by countering exogenous contaminants in livestock.

Integrative Analysis of Transcriptome and GWAS Data to Identify the Hub Genes Associated With Milk Yield Trait in Buffalo

The mammary gland is the production organ in mammals that is of great importance for milk production and quality. However, characterization of the buffalo mammary gland transcriptome and identification of the valuable candidate genes that affect milk production is limited. Here, we performed the differential expressed genes (DEGs) analysis of mammary gland tissue on day 7, 50, 140, and 280 after calving and conducted gene-based genome-wide association studies (GWAS) of milk yield in 935 Mediterranean buffaloes. We then employed weighted gene co-expression network analysis (WGCNA) to identify specific modules and hub genes related to milk yield based on gene expression profiles and GWAS data. The results of the DEGs analysis showed that a total of 1,420 DEGs were detected across different lactation points. In the gene-based analysis, 976 genes were found to have genome-wide association (P ≤ 0.05) that could be defined as the nominally significant GWAS geneset (NSGG), 9 of which were suggestively associated with milk yield (P < 10⁻⁴). Using the WGCNA analysis, 544 and 225 genes associated with milk yield in the turquoise module were identified from DEGs and NSGG datasets, respectively. Several genes (including BNIPL, TUBA1C, C2CD4B, DCP1B, MAP3K5, PDCD11, SRGAP1, GDPD5, BARX2, SCARA3, CTU2, and RPL27A) were identified and considered as the hub genes because they were involved in multiple pathways related to milk production. Our findings provide an insight into the dynamic characterization of the buffalo mammary gland transcriptome, and these potential candidate genes may be valuable for future functional characterization of the buffalo mammary gland.

Breast tumour organoids: promising models for the genomic and functional characterisation of breast cancer

Until recently, established cancer cell lines have been used extensively in breast cancer research, due largely to the difficulties associated with the manipulation and long-term maintenance in culture of primary tumour cells from patients. The recent development of organoid cultures has provided new opportunities to model and analyse patient samples, allowing the propagation of malignant cells under conditions that resemble the three-dimensional growth of breast tumours. They have proved efficacious in preserving the heterogeneity of primary samples and are emerging as a new model to further characterise the molecular features of breast cancer. Organoids formed from patient-derived cells are now in use for the evaluation of drug sensitivity and to validate disease-causing genomic variations. Here, the advantages and limitations of organoid cultures will be discussed and compared with the parallel development of other two- and three-dimensional culture strategies and with patient-derived xenografts. In particular, we will focus on the molecular characterisation of breast cancer organoids and provide some examples of how they have been used in functional studies.

JNK Promotes Epithelial Cell Anoikis by Transcriptional and Post-translational Regulation of BH3-Only Proteins

Developmental morphogenesis, tissue injury, and oncogenic transformation can cause the detachment of epithelial cells. These cells are eliminated by a specialized form of apoptosis (anoikis). While the processes that contribute to this form of cell death have been studied, the underlying mechanisms remain unclear. Here, we tested the role of the cJUN NH₂-terminal kinase (JNK) signaling pathway using murine models with compound JNK deficiency in mammary and kidney epithelial cells. These studies demonstrated that JNK is required for efficient anoikis in vitro and in vivo. Moreover, JNK-promoted anoikis required pro-apoptotic members of the BCL2 family of proteins. We show that JNK acts through a BAK/BAX-dependent apoptotic pathway by increasing BIM expression and phosphorylating BMF, leading to death of detached epithelial cells.

The cJUN NH2-terminal kinase (JNK) signaling pathway promotes genome stability and prevents tumor initiation

Breast cancer is the most commonly diagnosed malignancy in women. Analysis of breast cancer genomic DNA indicates frequent loss-of-function mutations in components of the cJUN NH₂-terminal kinase (JNK) signaling pathway. Since JNK signaling can promote cell proliferation by activating the AP1 transcription factor, this apparent association of reduced JNK signaling with tumor development was unexpected. We examined the effect of JNK deficiency in the murine breast epithelium. Loss of JNK signaling caused genomic instability and the development of breast cancer. Moreover, JNK deficiency caused widespread early neoplasia and rapid tumor formation in a murine model of breast cancer. This tumor suppressive function was not mediated by a role of JNK in the growth of established tumors, but by a requirement of JNK to prevent tumor initiation. Together, these data identify JNK pathway defects as ‘driver’ mutations that promote genome instability and tumor initiation.

As cells in our body grow and divide, their DNA can experience changes or damage. Most of these ‘mutations’ are harmless, or quickly fixed by the body. Yet, sometimes a mutation can trigger a chain of genetic events that drives the cells to multiply uncontrollably, which leads to tumors. Identifying these ‘driver mutations’ is complex, but key to understanding how cancers start and can be fought.

Breast cancer is the most common type of cancer diagnosed in women worldwide. Large studies have focused on sequencing the DNA of cancerous breast cells to try to identify the mutations that started the cancer. Results show that, in these cells, a biological mechanism called the JNK signaling pathway is often inactivated because mutations affect the molecules that take part in this process. Like a chain reaction, the proteins of the JNK pathway act on each other until the last one, called JNK, gets switched on. This protein then goes on to participate in a number of cellular processes such as DNA repair. Is it possible that mutations in this pathway actually drive cancer, and if so, how?

Girnius et al. addressed these questions by inactivating the JNK pathway in the breast cells of mice. Over the next year and a half, the JNK-deficient animals were more likely to get breast cancer than normal mice. Further experiments showed that, in breast cells, the JNK protein prevented tumors from appearing. However, once the tumors were present, it was less effective at stopping them from growing. The DNA of the breast cancer cells with no JNK protein also contained more genetic changes and mistakes. This suggests that the JNK signaling pathway helps to keep the genetic information ‘healthy’. This may be because, normally, the JNK protein activates processes that fix DNA mutations. Taken together, the results presented by Girnius et al. show that genetic changes which inactivate the JNK pathway can drive the development of breast cancer.

Certain anti-cancer drugs kill cancerous cells by damaging their DNA. Breast tumor cells with inactive JNK pathways are less able to repair their genetic information, and so these drugs could potentially work well on them. Future experiments will be needed to test this hypothesis.

Predicting high-risk endometrioid carcinomas using proteins

Background

The lethality of endometrioid endometrial cancer (EEC) is primarily attributable to advanced-stage diseases. We sought to develop a biomarker model that predicts EEC surgical stage at the time of clinical diagnosis.

Results

PSES was significantly correlated with surgical stage in the TCGA cohort (P < 0.0001) and in the validation cohort (P = 0.0003). Even among grade 1 or 2 tumors, PSES was significantly higher in advanced than in early stage tumors in both the TCGA (P = 0.005) and MD Anderson Cancer Center (MDACC) (P = 0.006) cohorts. Patients with positive PSES score had significantly shorter progression-free survival than those with negative PSES in the TCGA (hazard ratio [HR], 2.033; 95% CI, 1.031 to 3.809; P = 0.04) and validation (HR, 3.306; 95% CI, 1.836 to 9.436; P = 0.0007) cohorts. The ErbB signaling pathway was most significantly enriched in the PSES proteins and downregulated in advanced stage tumors.

Methods

Using reverse-phase protein array expression profiles of 170 antibodies for 210 EEC cases from TCGA, we constructed a Protein Scoring of EEC Staging (PSES) scheme comprising 6 proteins (3 of them phosphorylated) for surgical stage prediction. We validated and evaluated its diagnostic potential in an independent cohort of 184 EEC cases obtained at MDACC using receiver operating characteristic curve analyses. Kaplan-Meier survival analysis was used to examine the association of PSES score with patient outcome, and Ingenuity pathway analysis was used to identify relevant signaling pathways. Two-sided statistical tests were used.

Conclusions

PSES may provide clinically useful prediction of high-risk tumors and offer new insights into tumor biology in EEC.

Cancer reversion with oocyte extracts is mediated by cell cycle arrest and induction of tumour dormancy

Inducing stable control of tumour growth by tumour reversion is an alternative approach to cancer treatment when eradication of the disease cannot be achieved. The process requires re-establishment of normal control mechanisms that are lost in cancer cells so that abnormal proliferation can be halted. Embryonic environments can reset cellular programmes and we previously showed that axolotl oocyte extracts can reprogram breast cancer cells and reverse their tumorigenicity. In this study, we analysed the gene expression profiles of oocyte extract-treated tumour xenografts to show that tumour reprogramming involves cell cycle arrest and acquisition of a quiescent state. Tumour dormancy is associated with increased P27 expression, restoration of RB function and downregulation of mitogen-activated signalling pathways. We also show that the quiescent state is associated with increased levels of H4K20me3 and decreased H4K20me1, an epigenetic profile leading to chromatin compaction. The epigenetic reprogramming induced by oocyte extracts is required for RB hypophosphorylation and induction of P27 expression, both occurring during exposure to the extracts and stably maintained in reprogrammed tumour xenografts. Therefore, this study demonstrates the value of oocyte molecules for inducing tumour reversion and for the development of new chemoquiescence-based therapies.

The cJUN NH2-terminal kinase (JNK) pathway contributes to mouse mammary gland remodeling during involution

Involution returns the lactating mammary gland to a quiescent state after weaning. The mechanism of involution involves collapse of the mammary epithelial cell compartment. To test whether the cJUN NH₂-terminal kinase (JNK) signal transduction pathway contributes to involution, we established mice with JNK deficiency in the mammary epithelium. We found that JNK is required for efficient involution. JNK deficiency did not alter the STAT3/5 or SMAD2/3 signaling pathways that have been previously implicated in this process. Nevertheless, JNK promotes the expression of genes that drive involution, including matrix metalloproteases, cathepsins, and BH3-only proteins. These data demonstrate that JNK has a key role in mammary gland involution post lactation.

HLJ1 (DNAJB4) Gene Is a Novel Biomarker Candidate in Breast Cancer

Breast cancer is the most common cancer type and cause of cancer-related mortality among women worldwide. New biomarker discovery is crucial for diagnostic innovation and personalized medicine in breast cancer. Heat shock proteins (HSPs) have been increasingly reported as biomarkers and potential drug targets for cancers. HLJ1 (DNAJB4) belongs to the DNAJ (HSP40) family of HSPs and is regarded as a tumor suppressor gene in lung, colon, and gastric cancers. However, the role of the HLJ1 gene in breast cancer is currently unknown. We evaluated the role of the HLJ1 gene in breast cancer progression by analyzing its in vitro and in vivo expression and its genetic/epigenetic alterations. HLJ1 expression was found to be reduced or lost in breast cancer cell lines (SK-BR-3, MDA-MB-231, ZR-75-1) compared with the nontumorigenic mammary epithelial cell line (MCF 10A). In a clinical context for breast cancer progression, the HLJ1 expression was significantly less frequent in invasive breast carcinoma samples (n = 230) compared with normal breast tissue (n = 100), benign neoplasia (n = 53), and ductal carcinoma in situ (n = 21). In methylation analyses by the combined bisulfite restriction analysis assay, the CpG island located in the 5'-flanking region of the HLJ1 gene was found to be methylated in breast cancer cell lines. HLJ1 expression was restored in the ZR-75-1 cell line by DNA demethylating agent 5-Aza-2'-deoxycytidine (5-AzadC) and histone deacetylase inhibitor trichostatin A. These new observations support the idea that HLJ1 is a tumor suppressor candidate and potential biomarker for breast cancer. Epigenomic mechanisms such as CpG methylation and histone deacetylation might contribute to downregulation of HLJ1 expression. We call for future functional, epigenomic, and clinical studies to ascertain the contribution of HLJ1 to breast cancer pathogenesis and, importantly, evaluate its potential for biomarker development in support of personalized medicine diagnostic innovation in clinical oncology.

Insights into exchange factor directly activated by cAMP (EPAC) as potential target for cancer treatment

Cancer remains a global health problem and approximately 1.7 million new cancer cases are diagnosed every year worldwide. Although diverse molecules are currently being explored as targets for cancer therapy the tumor treatment and therapy is highly tricky. Secondary messengers are important for hormone-mediated signaling pathway. Cyclic AMP (cAMP), a secondary messenger responsible for various physiological processes regulates cell metabolism by activating Protein kinase A (PKA) and by targeting exchange protein directly activated by cAMP (EPAC). EPAC is present in two isoforms EPAC1 and EPAC2, which exhibit different tissue distribution and is involved in GDP/GTP exchange along with activating Rap1- and Rap2-mediated signaling pathways. EPAC is also known for its dual role in cancer as pro- and anti-proliferative in addition to metastasis. Results after perturbing EPAC activity suggests its involvement in cancer cell migration, proliferation, and cytoskeleton remodeling which makes it a potential therapeutic target for cancer treatments.

Correlation of expression of WWOX and JNK with clinicopathologic features in human breast carcinoma

The aim of our study was to compare the expression levels of c-Jun N-terminal kinase (JNK) and WW domain-containing oxidoreductase (WWOX) in human breast carcinoma, to analyze the correlation between the expression of WWOX and JNK with the clinicopathologic features of human breast carcinoma, and to explore the potential mechanism of their antitumor effects. The mRNA and protein levels of WWOX and JNK in forty paired breast carcinoma tissues and the adjacent normal tissues were detected by real-time quantitative polymerase chain reaction (RT-PCR) and Western blot analysis. Protein expression was further confirmed by immunohistochemistry (IHC). The mRNA expression levels of both JNK and WWOX were downregulated in carcinoma tissues relative to those in the adjacent normal tissues, as determined by Western blot analysis and IHC (P<0.01). JNK expression was positively correlated with WWOX expression (r=0.47, P=0.002). Both WWOX and JNK play important roles in breast cancer. Therefore, the antitumor ability of WWOX and JNK could supply significant information for therapeutic strategy.

c‑Jun N‑terminal kinase 3 signalling serves a potential role as a biomarker for determining the pathogenesis of Parkinson's disease

Parkinson's disease (PD) is a movement-associated disorder that specifically affects dopamine-producing neurons. The disease causes demyelation that adversely impacts upon the motor activity of the brain. Currently there are no promising biomarkers for PD; improved understanding of the molecular mechanisms underlying the different pathological stages of PD are required to enable identification of a novel biomarker. The present study successfully established a PD mouse model via nasal injection of 1‑methyl-4‑phenyl-1,2,3,6-tetrahydropyridine. The expression of c‑Jun N‑termal kinase 3 (JNK3) and caspase‑3 in two different pathological stages of PD were analysed using immunohistochemistry and western blot analysis. The results inidcated that the initial PD pathogenesis recovers on response to rasagiline. Immunohistochemistry and western blot analysis revealed that treatment with rasagiline positively regulated early‑stage PD pathogenesis by downregulating the expression of JNK3 and upregulating caspase‑3; however, there was no positive effect on the advanced stages of PD. Overall, these results concluded that rasagiline has the ability to inhibit the expression of JNK3 and upregulate caspase‑3 in early stages of PD; however, rasagline appears to have no impact on JNK3 and caspase‑3 levels in the advanced stages of PD.

Structural Basis for the Selective Inhibition of c-Jun N-Terminal Kinase 1 Determined by Rigid DARPin-DARPin Fusions

To untangle the complex signaling of the c-Jun N-terminal kinase (JNK) isoforms, we need tools that can selectively detect and inhibit individual isoforms. Because of the high similarity between JNK1, JNK2 and JNK3, it is very difficult to generate small-molecule inhibitors with this discriminatory power. Thus, we have recently selected protein binders from the designed ankyrin repeat protein (DARPin) library which were indeed isoform-specific inhibitors of JNK1 with low nanomolar potency. Here we provide the structural basis for their isotype discrimination and their inhibitory action. All our previous attempts to generate crystal structures of complexes had failed. We have now made use of a technology we recently developed which consists of rigid fusion of an additional special DARPin, which acts as a crystallization enhancer. This can be rigidly fused with different geometries, thereby generating a range of alternative crystal packings. The structures reveal the molecular basis for isoform specificity of the DARPins and their ability to prevent JNK activation and may thus form the basis of further investigation of the JNK family as well as novel approaches to drug design.

c-Jun N-terminal kinase 2 promotes enterocyte survival and goblet cell differentiation in the inflamed intestine

c-Jun N-terminal kinases (JNKs) contribute to immune signaling but their functional role during intestinal mucosal inflammation has remained ill defined. Using genetic mouse models, we characterized the role of JNK1 and JNK2 during homeostasis and acute colitis. Epithelial apoptosis, regeneration, differentiation, and barrier function were analyzed in intestinal epithelium-specific (ΔIEC) or complete JNK1 and bone marrow chimeric or complete JNK2 deficient mice as well as double-knockout animals (JNK1^ΔIECJNK2^-/-) during homeostasis and acute dextran sulfate sodium (DSS)-induced colitis. Results were confirmed using human HT-29 cells and wild-type or JNK2-deficient mouse intestinal organoid cultures. We show that nonhematopoietic JNK2 but not JNK1 expression confers protection from DSS-induced intestinal inflammation reducing epithelial barrier dysfunction and enterocyte apoptosis. JNK2 additionally enhanced Atonal homolog 1 expression, goblet cell and enteroendocrine cell differentiation, and mucus production under inflammatory conditions. Our results identify a protective role of epithelial JNK2 signaling to maintain mucosal barrier function, epithelial cell integrity, and mucus layer production in the event of inflammatory tissue damage.

Role of JNK signaling in oral cancer: A mini review

JNKs (c-Jun N-terminal kinases) belong to mitogen-activated protein kinases' family and become activated by several growth factors, stress, radiation, and other extracellular signals. In turn, JNK activation results in phosphorylation of downstream molecules involved in many normal cellular processes. Nevertheless, recent data have linked JNK signaling with several pathological conditions, including neurodegenerative diseases, inflammation, and cancer. The role of JNK in cancer remains controversial. Initially, JNK was thought to play a rather oncosuppressive role by mediating apoptosis in response to stress stimuli, inflammatory, or oncogenic signals. However, a number of studies have implicated JNK in malignant transformation and tumor growth. The contradictory functions of JNK in cancer may be due to the diversity of JNK upstream and downstream signaling and are under intensive investigation. This review summarizes current literature focusing on the significance of JNK pathway in cancer development and progression, particularly addressing its role in oral cancer. Understanding the complexity of JNK signaling has the potential to elucidate important molecular aspects of oral cancer, possibly leading to development of novel and individualized therapeutic strategies.

An In Vivo Functional Screen Identifies JNK Signaling As a Modulator of Chemotherapeutic Response in Breast Cancer

Chemotherapy remains the mainstay of treatment for advanced breast cancer; however, resistance is an inevitable event for the majority of patients with metastatic disease. Moreover, there is little information available to guide stratification of first-line chemotherapy, crucial given the common development of multidrug resistance. Here, we describe an in vivo screen to interrogate the response to anthracycline-based chemotherapy in a syngeneic metastatic breast cancer model and identify JNK signaling as a key modulator of chemotherapy response. Combining in vitro and in vivo functional analyses, we demonstrate that JNK inhibition both promotes tumor cell cytostasis and blocks activation of the proapoptotic protein Bax, thereby antagonizing chemotherapy-mediated cytotoxicity. To investigate the clinical relevance of this dual role of JNK signaling, we developed a proliferation-independent JNK activity signature and demonstrate high JNK activity to be enriched in triple-negative and basal-like breast cancer subtypes. Consistent with the dual role of JNK signaling in vitro, high-level JNK pathway activation in triple-negative breast cancers is associated both with poor patient outcome in the absence of chemotherapy treatment and, in neoadjuvant clinical studies, is predictive of enhanced chemotherapy response. These data highlight the potential of monitoring JNK activity as early biomarker of response to chemotherapy and emphasize the importance of rational treatment regimes, particularly when combining cytostatic and chemotherapeutic agents. Mol Cancer Ther; 16(9); 1967-78. ©2017 AACR.

JNK pathway inhibition enhances chemotherapeutic sensitivity to Adriamycin in nasopharyngeal carcinoma cells

The role of c-Jun N-terminal kinases (JNKs) in the pathogenesis of cancer is well-known due to their involvement in carcinogenesis. Although previous studies have discussed different functions of JNKs depending on cell type, the present study aimed to investigate the function of JNKs in nasopharyngeal carcinoma (NPC) cells, as well as their involvement in chemotherapy sensitivity to Adriamycin. The present results showed that Adriamycin administration reduced cell viability and led to elevated expressions of c-Jun, phosphorylated JNK and phosphorylated c-Jun, indicating an activated JNK pathway. Notably, JNK inhibition by SP600125 also reduced cell growth. Thus, Adriamycin treatment combined with SP600125 was more effective on cell growth inhibition than each agent alone. The apoptosis analysis confirmed the reduction in cell growth. Therefore, these data provide evidence that the JNK pathway activity is negatively associated with cell viability, and its decline could sensitize NPC cells to Adriamycin.

S100A4 Elevation Empowers Expression of Metastasis Effector Molecules in Human Breast Cancer

Many human glandular cancers metastasize along nerve tracts, but the mechanisms involved are generally poorly understood. The calcium-binding protein S100A4 is expressed at elevated levels in human cancers, where it has been linked to increased invasion and metastasis. Here we report genetic studies in a Drosophila model to define S100A4 effector functions that mediate metastatic dissemination of mutant Ras-induced tumors in the developing nervous system. In flies overexpressing mutant RasVal12 and S100A4, there was a significant increase in activation of the stress kinase JNK and production of the matrix metalloproteinase MMP1. Genetic or chemical blockades of JNK and MMP1 suppressed metastatic dissemination associated with S100A4 elevation, defining required signaling pathway(s) for S100A4 in this setting. In clinical specimens of human breast cancer, elevated levels of the mammalian paralogs MMP2, MMP9, and MMP13 are associated with a 4- to 9-fold relative decrease in patient survival. In individual tumors, levels of MMP2 and MMP13 correlated more closely with levels of S100A4, whereas MMP9 levels correlated more closely with the S100 family member S100P. Overall, our results suggest the existence of evolutionarily conserved pathways used by S100A4 to promote metastatic dissemination, with potential prognostic and therapeutic implications for metastasis by cancers that preferentially exploit nerve tract migration routes. Cancer Res; 77(3); 780-9. ©2016 AACR.

JNK Signaling: Regulation and Functions Based on Complex Protein-Protein Partnerships

The c-Jun N-terminal kinases (JNKs), as members of the mitogen-activated protein kinase (MAPK) family, mediate eukaryotic cell responses to a wide range of abiotic and biotic stress insults. JNKs also regulate important physiological processes, including neuronal functions, immunological actions, and embryonic development, via their impact on gene expression, cytoskeletal protein dynamics, and cell death/survival pathways. Although the JNK pathway has been under study for >20 years, its complexity is still perplexing, with multiple protein partners of JNKs underlying the diversity of actions. Here we review the current knowledge of JNK structure and isoforms as well as the partnerships of JNKs with a range of intracellular proteins. Many of these proteins are direct substrates of the JNKs. We analyzed almost 100 of these target proteins in detail within a framework of their classification based on their regulation by JNKs. Examples of these JNK substrates include a diverse assortment of nuclear transcription factors (Jun, ATF2, Myc, Elk1), cytoplasmic proteins involved in cytoskeleton regulation (DCX, Tau, WDR62) or vesicular transport (JIP1, JIP3), cell membrane receptors (BMPR2), and mitochondrial proteins (Mcl1, Bim). In addition, because upstream signaling components impact JNK activity, we critically assessed the involvement of signaling scaffolds and the roles of feedback mechanisms in the JNK pathway. Despite a clarification of many regulatory events in JNK-dependent signaling during the past decade, many other structural and mechanistic insights are just beginning to be revealed. These advances open new opportunities to understand the role of JNK signaling in diverse physiological and pathophysiological states.

Expression levels of JNK associated with polymorphic lactotransferrin haplotypes in human nasopharyngeal carcinoma

Lactotransferrin (LTF), a member of the transferrin family, serves a role in the innate immune response and is involved in anti-inflammatory, anti-microbial and anti-tumor activity. Alterations in the LTF gene are associated with an increased incidence of cancer. The LTF gene is polymorphic, and several common alleles may be observed in the general population. Our previous study identified a lower rate of occurrence of the 'A-G-G-T' haplotype (constructed with rs1126477, rs1126478, rs2073495 and rs9110) in nasopharyngeal carcinoma (NPC) patients compared with controls. In the present study, in order to elucidate a possible mechanism of LTF-mediated anti-tumor activity in NPC, the protein profiles of NPC and non-tumorous nasopharyngeal epithelium tissues with/without the 'A-G-G-T' haplotype were constructed using LTQ Orbitrap technology. The results revealed that c-Jun N-terminal kinase 2 (JNK2) was highly expressed in NPC tissues and non-tumor nasopharyngeal epithelium tissues without the 'A-G-G-T' haplotype. These results were confirmed by western blot analysis. Furthermore, microRNA (miRNA) microarray analysis was conducted to investigate the differential miRNA profiles of NPC and non-tumor nasopharyngeal epithelium tissues with/without the 'A-G-G-T' haplotype. It was observed that hsa-miR-1256 and hsa-miR-659, which are potentially targeted to the JNK2 gene, were downregulated in NPC tissues without the 'A-G-G-T' haplotype. Hsa-miR-298, another miRNA potentially targeted to the JNK2 gene, was downregulated in non-tumor nasopharyngeal epithelium tissues without the 'A-G-G-T' haplotype. In summary, these results suggested that the expression levels of JNK2 may be associated with polymorphic LTF haplotypes in human NPC.

The role of MAPK signaling pathway in the Her-2-positive meningiomas

Meningiomas are common types of adult nerve system tumors. Although most cases are considered benign, due to its high rate of recurrence and easy malignant progression to anaplastic meningioma they present a puzzle for the current treatment. The HER-2 oncogene has important value for meningioma cells development and progression. So far, little is known about the effect on the exact underlying signal pathway and molecular mechanisms of HER-2-positive meningioma cells. The goal of the present study was to determine the effects of HER-2 gene and possible involvement of MAPK signal pathway in human malignant meningioma. We applied q-PCR analysis, immunofluorescence (IF) staining, western blot analysis, animal model, MAPK inhibition, MTT assay and cell invasion analysis for the investigation. The results demonstrated that the downregulation of the expression of HER-2 significantly inhibited cell motility and proliferation of human meningioma cells in vivo. Accordingly, in the HER-2-overexpression meningioma cells with the inhibition of ERK1/2, ERK5, JNK, in the cells with the ERK1/2, ERK5 inhibition, protein expression was markedly suppressed as well as the cell proliferation resistance. No difference was observed in the HER-2-overexpression meningioma cells with the inhibition of JNK. These findings suggest that HER-2 gene can affect the proliferation ability of human meningioma cells in vivo and MAPK signal pathway may contribute to the carcinogenesis and development of human meningiomas combinating with HER-2.

Novel thiosemicarbazides induced apoptosis in human MCF-7 breast cancer cells via JNK signaling

In this study, novel thiosemicarbazides and 1,3,4-oxadiazoles were synthesized and evaluated for their anticancer effects on human MCF-7 breast cancer cell lines. Among the synthesized derivatives studied, compound 2-(3-(4-chlorophenyl)-3-hydroxybutanoyl)-N-phenylhydrazinecarbothioamide 4c showed the highest cytotoxicity against MCF-7 breast cancer cells as it reduced cell viability to approximately 15% compared to approximately 25% in normal breast epithelial cells. Therefore, we focused on 4c for further investigations. Our data showed that 4c induced apoptosis in MCF-7 cells which was further confirmed by TUNEL assay. Western blotting analysis showed that compound 4c up-regulated the pro-survival proteins Bax, Bad and ERK1/2, while it down-regulated anti-apoptotic proteins Bcl-2, Akt and STAT-3. Additionally, 4c induced phosphorylation of SAPK/JNK in MCF-7 cells. Pretreatment of MCF-7 cells with 10 µM of JNK inhibitor significantly reduced 4c-induced apoptosis. Molecular docking results suggested that compound 4c showed a binding pattern close to the pattern observed in the structure of the lead fragment bound to JNK1. Collectively, the data of current study suggested that the thiosemicarbazide 4c might trigger apoptosis in human MCF-7 cells by targeting JNK signaling.

c-Jun N-terminal kinase 2 prevents luminal cell commitment in normal mammary glands and tumors by inhibiting p53/Notch1 and breast cancer gene 1 expression

Breast cancer is a heterogeneous disease with several subtypes carrying unique prognoses. Patients with differentiated luminal tumors experience better outcomes, while effective treatments are unavailable for poorly differentiated tumors, including the basal-like subtype. Mechanisms governing mammary tumor subtype generation could prove critical to developing better treatments. C-Jun N-terminal kinase 2 (JNK2) is important in mammary tumorigenesis and tumor progression. Using a variety of mouse models, human breast cancer cell lines and tumor expression data, studies herein support that JNK2 inhibits cell differentiation in normal and cancer-derived mammary cells. JNK2 prevents precocious pubertal mammary development and inhibits Notch-dependent expansion of luminal cell populations. Likewise, JNK2 suppresses luminal populations in a p53-competent Polyoma Middle T-antigen tumor model where jnk2 knockout causes p53-dependent upregulation of Notch1 transcription. In a p53 knockout model, JNK2 restricts luminal populations independently of Notch1, by suppressing Brca1 expression and promoting epithelial to mesenchymal transition. JNK2 also inhibits estrogen receptor (ER) expression and confers resistance to fulvestrant, an ER inhibitor, while stimulating tumor progression. These data suggest that therapies inhibiting JNK2 in breast cancer may promote tumor differentiation, improve endocrine therapy response, and inhibit metastasis.