MKK3 modulates JNK-dependent cell migration and invasion

Gp93 inhibits unfolded protein response-mediated c-Jun N-terminal kinase activation and cell invasion

In eukaryotes, Hsp90B1 serves as a vital chaperonin, facilitating the accurate folding of proteins. Interestingly, Hsp90B1 exhibits contrasting roles in the development of various types of cancers, although the underlying reasons for this duality remain enigmatic. Through the utilization of the Drosophila model, this study unveils the functional significance of Gp93, the Drosophila ortholog of Hsp90B1, which hitherto had limited reported developmental functions. Employing the Drosophila cell invasion model, we elucidated the pivotal role of Gp93 in regulating cell invasion and modulating c-Jun N-terminal kinase (JNK) activation. Furthermore, our investigation highlights the involvement of the unfolded protein response-associated IRE1/XBP1 pathway in governing Gp93 depletion-induced, JNK-dependent cell invasion. Collectively, these findings not only uncover a novel molecular function of Gp93 in Drosophila, but also underscore a significant consideration pertaining to the testing of Hsp90B1 inhibitors in cancer therapy.

Experience-dependent glial pruning of synaptic glomeruli during the critical period

Critical periods are temporally-restricted, early-life windows when sensory experience remodels synaptic connectivity to optimize environmental input. In the Drosophila juvenile brain, critical period experience drives synapse elimination, which is transiently reversible. Within olfactory sensory neuron (OSN) classes synapsing onto single projection neurons extending to brain learning/memory centers, we find glia mediate experience-dependent pruning of OSN synaptic glomeruli downstream of critical period odorant exposure. We find glial projections infiltrate brain neuropil in response to critical period experience, and use Draper (MEGF10) engulfment receptors to prune synaptic glomeruli. Downstream, we find antagonistic Basket (JNK) and Puckered (DUSP) signaling is required for the experience-dependent translocation of activated Basket into glial nuclei. Dependent on this signaling, we find critical period experience drives expression of the F-actin linking signaling scaffold Cheerio (FLNA), which is absolutely essential for the synaptic glomeruli pruning. We find Cheerio mediates experience-dependent regulation of the glial F-actin cytoskeleton for critical period remodeling. These results define a sequential pathway for experience-dependent brain synaptic glomeruli pruning in a strictly-defined critical period; input experience drives neuropil infiltration of glial projections, Draper/MEGF10 receptors activate a Basket/JNK signaling cascade for transcriptional activation, and Cheerio/FLNA induction regulates the glial actin cytoskeleton to mediate targeted synapse phagocytosis.

Knockdown of BUB1B Inhibits the Proliferation, Migration, and Invasion of Colorectal Cancer by Regulating the JNK/c-Jun Signaling Pathway

Background: Colorectal cancer (CRC) ranks as the third most common cancer, accounting for a significant number of cancer-related deaths worldwide every year. Yet, the molecular mechanisms responsible for the progression of this malignancy are not fully understood. Numerous studies indicate that BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) plays a role in the progression of various malignant tumors. However, the specific biological functions and the detailed mechanisms of how BUB1B influences CRC are still not completely known. This study aimed to explore the expression and role of BUB1B in CRC. Materials and Methods: To achieve this, the expression levels of BUB1B in human CRC tissues and cell lines were examined using real-time polymerase chain reaction and Western blotting. The role and associated mechanisms of BUB1B in CRC cell progression were assessed both in vitro and in vivo using RNA interference. Results: The findings of this study revealed an elevated expression of BUB1B in both CRC tissues and cell lines. The silencing of BUB1B in CRC cell lines notably inhibited cell proliferation, migration, and invasion, leading to cell cycle arrest and apoptosis. In addition, the knockdown of BUB1B inhibited the JNK/c-Jun signaling pathway, increased the expression of proapoptotic proteins, and decreased the expression of antiapoptotic proteins. The effects of BUB1B knockdown on CRC cell progression were reversed by the JNK activator PAF(C-16). Conclusions: In summary, the suppression of BUB1B hindered malignant tumor progression and heightened apoptosis and cell cycle arrest in CRC cells via the JNK/c-Jun pathway. Importantly, the removal of BUB1B expression curtailed tumor growth in human CRC xenografts in nude mice, suggesting its potential as a promising therapeutic target for CRC patients. ClinicalTrials.gov ID: No.2019 K-C086.

Activated MKK3/MYC crosstalk impairs dabrafenib response in BRAFV600E colorectal cancer leading to resistance

Colorectal cancer (CRC) patients with BRAF mutations develop resistance to BRAF inhibitors at a very early stage. Understanding the molecular mechanisms involved in BRAF inhibitor resistance is critical for the development of novel therapeutic opportunities for this subtype of CRC patients. CRC cells bearing BRAF mutations are mostly sensitive to the abrogation of Mitogen-Activated Protein Kinase Kinase 3 (MKK3), a specific activator of p38MAPKs signaling, suggesting that BRAF alterations might addict CRC cells to the MKK3/p38MAPK signaling. Interestingly, publicly available gene expression profiling data show significantly higher MKK3 transcript levels in CRC lines with acquired resistance to BRAF inhibitors. Herein, we investigated the roles of MKK3 in the response to BRAF targeting (dabrafenib) with COLO205 and HT29 BRAFV600E CRC lines and derived dabrafenib-resistant (DABR) sublines. Dabrafenib treatments reduce MKK3 activation by inducing autophagy in parental but not DABR cells. The MKK3 knockdown induces cell death in DABR cells, whereas ectopic MKK3 expression reduces dabrafenib sensitivity in parental cells. Mechanistically, activated MKK3 interacts and co-localizes with c-Myc oncoprotein (MYC), sustaining MYC protein stability and thus preventing the dabrafenib induced effects in CRC DABR cells both in vitro and in vivo. Overall, we identify a novel molecular mechanism beyond the dabrafenib resistance, shedding light on an uncovered vulnerability for the development of novel therapeutic opportunities in BRAFV600E CRC.

Comprehensive bioinformatic analysis of the expression and prognostic significance of TSC22D domain family genes in adult acute myeloid leukemia

BACKGROUND

TSC22D domain family genes, including TSC22D1-4, play a principal role in cancer progression. However, their expression profiles and prognostic significance in adult acute myeloid leukemia (AML) remain unknown.

METHODS

The online databases, including HPA, CCLE, EMBL-EBI, GEPIA2, BloodSpot, GENT2, UCSCXenaShiny, GSCALite, cBioportal, and GenomicScape, utilized the data of TCGA and GEO to investigate gene expression, mutation, copy number variation (CNV), and prognostic significance of the TSC22D domain family in adult AML. Computational analysis of resistance (CARE) was used to explore the effect of TSC22D3 expression on drug response. Functional enrichment analysis of TSC22D3 was performed in the TRRUST Version 2 database. The STRING, Pathway Commons, and AnimalTFDB3.0 databases were used to investigate the protein-protein interaction (PPI) network of TSC22D3. Harmonizome was used to predict target genes and kinases regulated by TSC22D3. The StarBase v2.0 and CancermiRNome databases were used to predict miRNAs regulated by TSC22D3. UCSCXenaShiny was used to investigate the correlation between TSC22D3 expression and immune infiltration.

RESULTS

Compared with normal adult hematopoietic stem cells (HSCs), the expression of TSC22D3 and TSC22D4 in adult AML tissues was markedly up-regulated, whereas TSC22D1 expression was markedly down-regulated. The expression of TSC22D1 and TSC22D3 was significantly increased in adult AML tissues compared to normal adult tissues. High TSC22D3 expression was significantly associated with poor overall survival (OS) and event-free survival (EFS) in adult AML patients. Univariate and multivariate Cox analysis showed that overexpression of TSC22D3 was independently associated with adverse OS of adult AML patients. High TSC22D3 expression had a adverse impact on OS and EFS of adult AML patients in the chemotherapy group. TSC22D3 expression correlated with drug resistance to BCL2 inhibitors. Functional enrichment analysis indicated that TSC22D3 might promote AML progression. MIR143-3p sponging TSC22D3 might have anti-leukemia effect in adult AML.

CONCLUSIONS

A significant increase in TSC22D3 expression was observed in adult AML tissues compared to normal adult HSCs and tissues. The prognosis of adult AML patients with high TSC22D3 expression was unfavorable, which could severe as a new prognostic biomarker and potential target for adult AML.

Meso-Hannokinol inhibits breast cancer bone metastasis via the ROS/JNK/ZEB1 axis

Distal metastases from breast cancer, especially bone metastases, are extremely common in the late stages of the disease and are associated with a poor prognosis. EMT is a biomarker of the early process of bone metastasis, and MMP-9 and MMP-13 are important osteoclastic activators. Previously, we found that meso-Hannokinol (HA) could significantly inhibit EMT and MMP-9 and MMP-13 expressions in breast cancer cells. On this basis, we further explored the role of HA in breast cancer bone metastasis. In vivo, we established a breast cancer bone metastasis model by intracardially injecting breast cancer cells. Intraperitoneal injections of HA significantly reduced breast cancer cell metastasis to the leg bone in mice and osteolytic lesions caused by breast cancer. In vitro, HA inhibited the migration and invasion of breast cancer cells and suppressed the expressions of EMT, MMP-9, MMP-13, and other osteoclastic activators. HA inhibited EMT and MMP-9 by activating the ROS/JNK pathway as demonstrated by siJNK and SP600125 inhibition of JNK phosphorylation and NAC scavenging of ROS accumulation. Moreover, HA promoted bone formation and inhibited bone resorption in vitro. In conclusion, our findings suggest that HA may be an excellent candidate for treating breast cancer bone metastasis.

Metastatic effects of environmental carcinogens mediated by MAPK and UPR pathways with an in vivo Drosophila Model

Metastasis includes tumor invasion and migration and underlies over 90% of cancer mortality. The metastatic effects of environmental carcinogens raised serious health concerns. However, the underlying mechanisms remained poorly studied. In the present study, an in vivo Ras^V12/lgl^-/- model of the fruitfly, Drosophila melanogaster, with an 8-day exposure was employed to explore the metastatic effects of 3,3',4,4',5-pentachlorobiphenyl (PCB126), perfluorooctanoic acid (PFOA) and cadmium chloride (CdCl₂). At 1.0 mg/L, PCB126, PFOA, and CdCl₂ significantly increased tumor invasion rates by 1.32-, 1.33-, and 1.29-fold of the control, respectively. They also decreased the larval body weight and locomotion behavior. Moreover, they commonly disturbed the expression levels of target genes in MAPK and UPR pathways, and their metastatic effects were significantly abolished by the addition of p38 inhibitor (SB203580), JNK inhibitor (SP600125) and IRE1 inhibitor (KIRA6). Notably, the addition of the IRE inhibitor significantly influenced sna/E-cad pathway which is essential in both p38 and JNK regulations. The results demonstrated an essential role of sna/E-cad in connecting the effects of carcinogens on UPR and MAPK regulations and the resultant metastasis.

Stellettin B Isolated from Stelletta Sp. Reduces Migration and Invasion of Hepatocellular Carcinoma Cells through Reducing Activation of the MAPKs and FAK/PI3K/AKT/mTOR Signaling Pathways

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, and there is currently a lack of effective treatment options to control the metastasis. This study was performed to examine the mechanisms of the migration and invasion characteristics of HCC, with the aim of reducing metastasis by inhibiting cancer cell migration and invasion. In this study, we used Stellettin B, an active compound isolated from Stelletta sponges, as the experimental drug and evaluated its inhibition effects on cell migration and invasion in human hepatoma cells (HA22T and HepG2). MTT assay, gelatin zymography, and western blotting were employed. The results showed that Stellettin B significantly inhibited the protein expressions of MMP-2, MMP-9, and uPA, while upregulating the protein expressions of TIMP-1 and TIMP-2. The expressions of p-FAK, p-PI3K, p-AKT, p-mTOR, and MAPKs (p-JNK, p-JUN, p-MAPKp38, and p-ERK) were decreased with increasing concentrations of Stellettin B. Our results suggest that Stellettin B-dependent downregulation of MMP-2 and MMP-9 activities could be mediated by FAK/PI3K/AKT/mTOR and MAPKs signaling pathways in HA22T and HepG2 cells, preventing HCC invasion and migration.

Epidermal growth factor receptor cascade prioritizes the maximization of signal transduction

Many studies have been performed to quantify cell signaling. Cell signaling molecules are phosphorylated in response to extracellular stimuli, with the phosphorylation sequence forming a signal cascade. The information gain during a signal event is given by the logarithm of the phosphorylation molecule ratio. The average information gain can be regarded as the signal transduction quantity (ST), which is identical to the Kullback-Leibler divergence (KLD), a relative entropy. We previously reported that if the total ST value in a given signal cascade is maximized, the ST rate (STR) of each signaling molecule per signal duration (min) approaches a constant value. To experimentally verify this theoretical conclusion, we measured the STR of the epidermal growth factor (EGF)-related cascade in A431 skin cancer cells following stimulation with EGF using antibody microarrays against phosphorylated signal molecules. The results were consistent with those from the theoretical analysis. Thus, signaling transduction systems may adopt a strategy that prioritizes the maximization of ST. Furthermore, signal molecules with similar STRs may form a signal cascade. In conclusion, ST and STR are promising properties for quantitative analysis of signal transduction.

The CRTC-CREB axis functions as a transcriptional sensor to protect against proteotoxic stress in Drosophila

cAMP Responsible Element Binding Protein (CREB) is an evolutionarily conserved transcriptional factor that regulates cell growth, synaptic plasticity and so on. In this study, we unexpectedly found proteasome inhibitors, such as MLN2238, robustly increase CREB activity in adult flies through a large-scale compound screening. Mechanistically, reactive oxidative species (ROS) generated by proteasome inhibition are required and sufficient to promote CREB activity through c-Jun N-terminal kinase (JNK). In 293 T cells, JNK activation by MLN2238 is also required for increase of CREB phosphorylation at Ser¹³³. Meanwhile, transcriptome analysis in fly intestine identified a group of genes involved in redox and proteostatic regulation are augmented by overexpressing CRTC (CREB-regulated transcriptional coactivator). Intriguingly, CRTC overexpression in muscles robustly restores protein folding and proteasomal activity in a fly Huntington's disease (HD) model, and ameliorates HD related pathogenesis, such as protein aggregates, motility, and lifespan. Moreover, CREB activity increases during aging, and further enhances its activity can suppress protein aggregates in aged muscles. Together, our results identified CRTC/CREB downstream ROS/JNK signaling as a conserved sensor to tackle oxidative and proteotoxic stresses. Boosting CRTC/CREB activity is a potential therapeutic strategy to treat aging related protein aggregation diseases.

The Role of PKC-MAPK Signalling Pathways in the Development of Hyperglycemia-Induced Cardiovascular Complications

Cardiovascular disease is the most common cause of death among diabetic patients worldwide. Hence, cardiovascular wellbeing in diabetic patients requires utmost importance in disease management. Recent studies have demonstrated that protein kinase C activation plays a vital role in the development of cardiovascular complications via its activation of mitogen-activated protein kinase (MAPK) cascades, also known as PKC-MAPK pathways. In fact, persistent hyperglycaemia in diabetic conditions contribute to preserved PKC activation mediated by excessive production of diacylglycerol (DAG) and oxidative stress. PKC-MAPK pathways are involved in several cellular responses, including enhancing oxidative stress and activating signalling pathways that lead to uncontrolled cardiac and vascular remodelling and their subsequent dysfunction. In this review, we discuss the recent discovery on the role of PKC-MAPK pathways, the mechanisms involved in the development and progression of diabetic cardiovascular complications, and their potential as therapeutic targets for cardiovascular management in diabetic patients.

Inflammation down regulates stromal cell-derived factor 1α in the early phase of pulpitis

The key to prevent pulp necrosis in the early stage of pulpitis is to promote tissue repair, which begins with cell migration. Stromal cell-derived factor 1α (SDF-1α) has been proven to promote cell migration. Related research has so far concentrated on the biological effects of SDF-1α while its expression in pulpitis is still unclear. We investigated the effect of inflammation on SDF-1α in dental pulp and the underlying regulatory mechanisms. First, rat pulpitis models were established by exposing pulp. SDF-1α was decreased on the 3rd day but increased on the 7th day. Next, lipopolysaccharide from Porphyromonas gingivalis (Pg.LPS) was applied to dental pulp cells (DPCs). Within 24 h, SDF-1α decreased, but after 48 h, it steadily increased. Similarly, SDF-1α expression in human chronic pulpitis tissues was also increased. To investigate the effect of altered SDF-1α on DPC migration, cell supernatants collected following Pg.LPS treatment were utilized to stimulate DPCs, and the number of migrated cells was correlated with changes in SDF-1α secretion. Finally, we explored the regulatory mechanisms of SDF-1α down-regulation in the early phase of pulpitis. Within 24 h, JNK/c-Jun pathway was activated in DPC inflammation. When JNK pathway was suppressed, SDF-1α rose. Furthermore, tumor necrosis factor receptor 2 (TNFR2) and apoptosis signal-regulated kinase-interacting protein 1 (AIP1) were up-regulated. Knockdown of them abolished Pg.LPS-induced activation of JNK and c-Jun(Ser63) and significantly enhanced SDF-1α. Our findings indicated that in the early phase of pulpitis, inflammation suppressed SDF-1α by up-regulating TNFR2 and AIP1, which activated JNK/c-Jun(Ser63) pathway.

ANKFN1 plays both protumorigenic and metastatic roles in hepatocellular carcinoma

Ankyrin repeat and fibronectin type III domain containing 1 (ANKFN1) is reported to be involved in human height and developmental abnormalities, but the expression profile and molecular function of ANKFN1 in hepatocellular carcinoma (HCC) remain unknown. This study aimed to evaluate the clinical significance and biological function of ANKFN1 in HCC and investigate whether ANKFN1 can be used for differential diagnosis in HCC. Here, we showed that ANKFN1 was upregulated in 126 tumor tissues compared with adjacent nontumorous tissues in HCC patients. The upregulation of ANKFN1 in HCC was associated with cirrhosis, alpha-fetoprotein (AFP) levels and poor prognosis. Moreover, silencing ANKFN1 expression suppressed HCC cell proliferation, migration, invasion, and metastasis in vitro and subcutaneous tumorigenesis in vivo. However, ANKFN1 overexpression promoted HCC proliferation and metastasis in an orthotopic liver transplantation model and attenuated the above biological effects in HCC cells. ANKFN1 significantly affected HCC cell proliferation by inducing G1/S transition and cell apoptosis. Mechanistically, we demonstrated that ANKFN1 promoted cell proliferation, migration, and invasion via activation of the cyclin D1/Cdk4/Cdk6 pathway by stimulating the MEK1/2-ERK1/2 pathway. Moreover, ANKFN1-induced cell proliferation, migration, and invasion were partially reversed by ERK1/2 inhibitors. Taken together, our results indicate that ANKFN1 promotes HCC cell proliferation and metastasis by activating the MEK1/2-ERK1/2 signaling pathway. Our work also suggests that ANKFN1 is a potential therapeutic target for HCC.

Usp8 promotes tumor cell migration through activating the JNK pathway

Tumor metastasis is the most cause of high mortality for cancer patients. Identification of novel factors that modulate tumor cell migration is of great significance for therapeutic strategies. Here, we find that the ubiquitin-specific protease 8 (Usp8) promotes tumor cell migration through activating the c-Jun N-terminal kinase (JNK) pathway. Genetic epistasis analyses uncover Usp8 acts upstream of Tak1 to control the JNK pathway. Consistently, biochemical results reveal that Usp8 binds Tak1 to remove ubiquitin modification from Tak1, leading to its stabilization. In addition, human USP8 also triggers tumor cell migration and activates the JNK pathway. Finally, we show that knockdown of USP8 in human breast cancer cells suppresses cell migration. Taken together, our findings demonstrate that a conserved Usp8-Tak1-JNK axis promotes tumor cell migration, and providing USP8 as a potential therapeutic target for cancer treatment.

Dissection of the MKK3 Functions in Human Cancer: A Double-Edged Sword?

The role played by MKK3 in human cancer is controversial. MKK3 is an evolutionarily conserved protein kinase that activates in response to a variety of stimuli. Phosphorylates, specifically the p38MAPK family proteins, contribute to the regulation of a plethora of cellular processes such as proliferation, differentiation, apoptosis, invasion, and cell migration. Genes in carcinogenesis are classified as oncogenes and tumor suppressors; however, a clear distinction is not always easily made as it depends on the cell context and tissue specificity. The aim of this study is the examination of the potential contribution of MKK3 in cancer through a systematic analysis of the recent literature. The overall results reveal a complex scenario of MKK3’s involvement in cancer. The oncogenic functions of MKK3 were univocally documented in several solid tumors, such as colorectal, prostate cancer, and melanoma, while its tumor-suppressing functions were described in glioblastoma and gastric cancer. Furthermore, a dual role of MKK3 as an oncogene as well as tumor a suppressor has been described in breast, cervical, ovarian, liver, esophageal, and lung cancer. However, overall, more evidence points to its role as an oncogene in these diseases. This review indicates that the oncogenic and tumor-suppressing roles of MKK3 are strictly dependent on the tumor type and further suggests that MKK3 could represent an efficient putative molecular target that requires contextualization within a specific tumor type in order to adequately evaluate its potential effectiveness in designing novel anticancer therapies. 

Proteome Landscape of Epithelial-to-Mesenchymal Transition (EMT) of Retinal Pigment Epithelium Shares Commonalities With Malignancy-Associated EMT

Stress and injury to the retinal pigment epithelium (RPE) often lead to dedifferentiation and epithelial-to-mesenchymal transition (EMT). These processes have been implicated in several retinal diseases, including proliferative vitreoretinopathy, diabetic retinopathy, and age-related macular degeneration. Despite the importance of RPE-EMT and the large body of data characterizing malignancy-related EMT, comprehensive proteomic studies to define the protein changes and pathways underlying RPE-EMT have not been reported. This study sought to investigate the temporal protein expression changes that occur in a human-induced pluripotent stem cell–based RPE-EMT model. We utilized multiplexed isobaric tandem mass tag labeling followed by high-resolution tandem MS for precise and in-depth quantification of the RPE-EMT proteome. We have identified and quantified 7937 protein groups in our tandem mass tag–based MS analysis. We observed a total of 532 proteins that are differentially regulated during RPE-EMT. Furthermore, we integrated our proteomic data with prior transcriptomic (RNA-Seq) data to provide additional insights into RPE-EMT mechanisms. To validate these results, we have performed a label-free single-shot data-independent acquisition MS study. Our integrated analysis indicates both the commonality and uniqueness of RPE-EMT compared with malignancy-associated EMT. Our comparative analysis also revealed that multiple age-related macular degeneration–associated risk factors are differentially regulated during RPE-EMT. Together, our integrated dataset provides a comprehensive RPE-EMT atlas and resource for understanding the molecular signaling events and associated biological pathways that underlie RPE-EMT onset. This resource has already facilitated the identification of chemical modulators that could inhibit RPE-EMT, and it will hopefully aid in ongoing efforts to develop EMT inhibition as an approach for the treatment of retinal disease.

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Proteomics data were integrated with prior transcriptomic (RNA-Seq) data on RPE-EMT.

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Dysregulated RPE-EMT proteome shares commonality with malignancy-associated EMT.

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Altered RPE-EMT proteome signatures correlated with known AMD-associated risk factors.

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Protein kinases and phosphatases crosstalk modulate RPE-EMT.

RasV12; scrib-/- Tumors: A Cooperative Oncogenesis Model Fueled by Tumor/Host Interactions

The phenomenon of how oncogenes and tumor-suppressor mutations can synergize to promote tumor fitness and cancer progression can be studied in relatively simple animal model systems such as Drosophila melanogaster. Almost two decades after the landmark discovery of cooperative oncogenesis between oncogenic Ras^V12 and the loss of the tumor suppressor scribble in flies, this and other tumor models have provided new concepts and findings in cancer biology that has remarkable parallels and relevance to human cancer. Here we review findings using the Ras^V12; scrib^-/- tumor model and how it has contributed to our understanding of how these initial simple genetic insults cooperate within the tumor cell to set in motion the malignant transformation program leading to tumor growth through cell growth, cell survival and proliferation, dismantling of cell-cell interactions, degradation of basement membrane and spreading to other organs. Recent findings have demonstrated that cooperativity goes beyond cell intrinsic mechanisms as the tumor interacts with the immediate cells of the microenvironment, the immune system and systemic organs to eventually facilitate malignant progression.

Discovery of the first chemical tools to regulate MKK3-mediated MYC activation in cancer

The transcription master regulator MYC plays an essential role in regulating major cellular programs and is a well-established therapeutic target in cancer. However, MYC targeting for drug discovery is challenging. New therapeutic approaches to control MYC-dependent malignancy are urgently needed. The mitogen-activated protein kinase kinase 3 (MKK3) binds and activates MYC in different cell types, and disruption of MKK3-MYC protein-protein interaction may provide a new strategy to target MYC-driven programs. However, there is no perturbagen available to interrogate and control this signaling arm. In this study, we assessed the drugability of the MKK3-MYC complex and discovered the first chemical tool to regulate MKK3-mediated MYC activation. We have designed a short 44-residue inhibitory peptide and developed a cell lysate-based time-resolved fluorescence resonance energy transfer (TR-FRET) assay to discover the first small molecule MKK3-MYC PPI inhibitor. We have optimized and miniaturized the assay into an ultra-high-throughput screening (uHTS) 1536-well plate format. The pilot screen of ~6,000 compounds of a bioactive chemical library followed by multiple secondary and orthogonal assays revealed a quinoline derivative SGI-1027 as a potent inhibitor of MKK3-MYC PPI. We have shown that SGI-1027 disrupts the MKK3-MYC complex in cells and in vitro and inhibits MYC transcriptional activity in colon and breast cancer cells. In contrast, SGI-1027 does not inhibit MKK3 kinase activity and does not interfere with well-known MKK3-p38 and MYC-MAX complexes. Together, our studies demonstrate the drugability of MKK3-MYC PPI, provide the first chemical tool to interrogate its biological functions, and establish a new uHTS assay to enable future discovery of potent and selective inhibitors to regulate this oncogenic complex.

DNMT1 Mediated CAHM Repression Promotes Glioma Invasion via SPAK/JNK Pathway

Gliomas are the most common and fatal brain tumors worldwide. Abnormal DNA promoter methylation is an important mechanism for gene loss of tumor suppressors. A long non-coding RNA colorectal adenocarcinoma hypermethylated (CAHM) has been reported to be nearly deleted in glioblastomas (GBMs). Nevertheless, the roles of CAHM in gliomas remain unknown up to now. In the present study, 969 glioma samples downloaded from the CGGA and Gravendeel databases were included. We found that CAHM expression was correlated with glioma grades, molecular subtype, IDH mutation status, and 1q/19p codel status. In glioma cells, CAHM is hypermethylated by DNA methyltransferase1 (DNMT1) and the loss of CAHM expression could be reversed by 5-Aza-2'-deoxycytidine (5-Aza), a specific inhibitor of DNA methyltransferases. Besides, the expression of CAHM was negatively associated with overall survival in both primary and recurrent gliomas. Moreover, the result of Gene Ontology (GO) analysis suggested that CAHM participated in negatively regulating cell development, nervous system development, neurogenesis, and integrin-mediated signaling pathway. Overexpression of CAHM inhibited glioma cell proliferation, clone formation, and invasion. Further exploring results showed that CAHM overexpression suppressed glioma migration and invasion through SPAK/MAPK pathway. Collectively, this study disclosed that CAHM might be a suppressor in gliomas.

Limited inhibition of multiple nodes in a driver network blocks metastasis

Metastasis suppression by high-dose, multi-drug targeting is unsuccessful due to network heterogeneity and compensatory network activation. Here, we show that targeting driver network signaling capacity by limited inhibition of core pathways is a more effective anti-metastatic strategy. This principle underlies the action of a physiological metastasis suppressor, Raf Kinase Inhibitory Protein (RKIP), that moderately decreases stress-regulated MAP kinase network activity, reducing output to transcription factors such as pro-metastastic BACH1 and motility-related target genes. We developed a low-dose four-drug mimic that blocks metastatic colonization in mouse breast cancer models and increases survival. Experiments and network flow modeling show limited inhibition of multiple pathways is required to overcome variation in MAPK network topology and suppress signaling output across heterogeneous tumor cells. Restricting inhibition of individual kinases dissipates surplus signal, preventing threshold activation of compensatory kinase networks. This low-dose multi-drug approach to decrease signaling capacity of driver networks represents a transformative, clinically relevant strategy for anti-metastatic treatment.

The miR-19b-3p-MAP2K3-STAT3 feedback loop regulates cell proliferation and invasion in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most refractory malignancies worldwide. Mitogen-activated protein kinase 3 (MAP2K3) has a contradictory role in tumor progression, and the function and expression patterns of MAP2K3 in ESCC remain to be determined. We found that MAP2K3 expression to be downregulated in ESCC, and MAP2K3 downregulation correlated with clinically poor survival. MAP2K3 inhibited ESCC cell proliferation and invasion in vitro and in vivo. MAP2K3 suppressed STAT3 expression and activation. Mechanistically, MAPSK3 interacted with MDM2 to promote STAT3 degradation via the ubiquitin-proteasome pathway. Furthermore, exosomal miR-19b-3p derived from the plasma of patients with ESCC could suppress MAP2K3 expression to promote ESCC tumorigenesis. STAT3 was found to bind to the MIR19B promoter and increased the expression of miR-19b-3p in ESCC cells. In summary, our results demonstrated that the miR-19b-3p-MAP2K3-STAT3 feedback loop regulates ESCC tumorigenesis and elucidates the potential of therapeutically targeting this pathway in ESCC.

ZnT7 RNAi favors RafGOFscrib-/--induced tumor growth and invasion in Drosophila through JNK signaling pathway

The disruption of zinc homeostasis has been identified in patients suffering from various cancers, but a causative relationship has not yet been established. Drosophila melanogaster has become a powerful model to study cancer biology. Here using a Drosophila model of malignant tumor Raf^GOFscrib^-/-, we observed that the tumor growth, invasion and migration were enhanced by silencing dZnT7, a zinc transporter localized on the Golgi apparatus. Further study indicated that the zinc deficiency in Golgi of dZnT7 RNAi resulted in ER stress which could activate the c-Jun-N-terminal Kinase (JNK) signaling and this process is mediated by Atg9. Lastly, we demonstrated that the exacerbation of dZnT7 RNAi on tumor was promoted by JNK signaling-dependent cell autonomous and non-autonomous autophagy. These findings suggest that zinc homeostasis in secretory compartments may provide a new therapeutic target for tumor treatment.

Nanospheres loaded with curcumin promote gut epithelial motility through F-actin-related migration signaling events

Curcumin, a hydrophobic polyphenol of turmeric, has a variety of biological functions as an herbal supplement, but its poor gastric absorption rate is one of the major factors limiting its oral bioavailability. In the present study, we investigated the functional role of nanospheres loaded with curcumin (nCur) with regard to the motility of gut epithelial HCT116 cells and enterocyte migration along the crypt-villus axis. nCur significantly increased the motility of HCT116 cells and showed much higher migration efficacy than the curcumin. nCur stimulated the small GTPases Rac1 and the phosphorylation of protein kinase C, responsible for the distinctive activation of the mitogen-activated protein kinases. Interestingly, nCur significantly induced the expression of α-actinin, profilin-1, and filamentous (F)-actin as regulated by the phosphorylation of nuclear factor-kappa B during its promotion of cell migration. In mouse models of gut epithelial migration, treatment with nCur had an enhancing effect on the movement of enterocytes along the crypt-villus axis and the expression of cytoskeletal reorganization-related factors. These results indicate that nCur is a functional agent that promotes gut epithelial motility through F-actin-related migration signaling events.

Rox8 promotes microRNA-dependent yki messenger RNA decay

The Hippo pathway is an evolutionarily conserved regulator of organ growth and tumorigenesis. In Drosophila, oncogenic Ras^V12 cooperates with loss-of-cell polarity to promote Hippo pathway-dependent tumor growth. To identify additional factors that modulate this signaling, we performed a genetic screen utilizing the Drosophila Ras ^V12 /lgl ^-/- in vivo tumor model and identified Rox8, a RNA-binding protein (RBP), as a positive regulator of the Hippo pathway. We found that Rox8 overexpression suppresses whereas Rox8 depletion potentiates Hippo-dependent tissue overgrowth, accompanied by altered Yki protein level and target gene expression. Mechanistically, Rox8 directly binds to a target site located in the yki 3' UTR, recruits and stabilizes the targeting of miR-8-loaded RISC, which accelerates the decay of yki messenger RNA (mRNA). Moreover, TIAR, the human ortholog of Rox8, is able to promote the degradation of yki mRNA when introduced into Drosophila and destabilizes YAP mRNA in human cells. Thus, our study provides in vivo evidence that the Hippo pathway is posttranscriptionally regulated by the collaborative action of RBP and microRNA (miRNA), which may provide an approach for modulating Hippo pathway-mediated tumorigenesis.

Identification of Hub Genes in Protective Effect of Astragaloside IV on Aconitine-Induced Cardiac Damage in Zebrafish Based on Bioinformatics Analysis

Accumulating evidence suggests that Astragaloside IV (AS-IV) improves cardiac function and protects the cardiovascular system. However, the molecular targets involved remain ambiguous. In this work, we report research suggesting that AS-IV can antagonize arrhythmias and reduce the cardiac damage induced by aconitine in zebrafish. Zebrafish have certain benefits with respect to studying the effect of drugs on cardiovascular disease. The possible mechanisms involved are analyzed, and hub gene targets are predicted. First, a model of cardiac damage induced by aconitine was created, and then a safe drug concentration of AS-IV was screened, and the appropriate drug dose gradient was selected within a safe drug concentration range. Second, we confirmed the protective effect of AS-IV in the cardiovascular system by observing changes in zebrafish heart rates and the cardiac and vascular structure. Third, we aimed to demonstrate the antagonistic mechanism of AS-IV on heart rate and cardiac damage induced by aconitine in zebrafish, with differentially expressed genes (DEGs) detected by RNA sequencing. The DEGs were then further analyzed by bioinformatic techniques, such as function enrichment analysis, protein-protein interaction network, and DNA-microRNA networks, for example. Next, we predicted the hub genes of the cardiac protective effects of AS-IV. Finally, we validated these genes in different transcriptome sequence datasets of cardiac damage. Thus, we conclude that miR-26b-5p/ATF3/JUN are key targets of AS-IV and play an important role in maintaining cardiac homeostasis and regulating cardiac remodeling.

The transcription factor Spalt and human homologue SALL4 induce cell invasion via the dMyc-JNK pathway in Drosophila

Cancer cell metastasis is a leading cause of mortality in cancer patients. Therefore, revealing the molecular mechanism of cancer cell invasion is of great significance for the treatment of cancer. In human patients, the hyperactivity of transcription factor Spalt-like 4 (SALL4) is sufficient to induce malignant tumorigenesis and metastasis. Here, we found that when ectopically expressing the Drosophila homologue spalt (sal) or human SALL4 in Drosophila, epithelial cells delaminated basally with penetration of the basal lamina and degradation of the extracellular matrix, which are essential properties of cell invasion. Further assay found that sal/SALL4 promoted cell invasion via dMyc-JNK signaling. Inhibition of the c-Jun N-terminal kinase (JNK) signaling pathway through suppressing matrix metalloprotease 1, or basket can achieve suppression of cell invasion. Moreover, expression of dMyc, a suppressor of JNK signaling, dramatically blocked cell invasion induced by sal/SALL4 in the wing disc. These findings reveal a conserved role of sal/SALL4 in invasive cell movement and link the crucial mediator of tumor invasion, the JNK pathway, to SALL4-mediated cancer progression.This article has an associated First Person interview with the first author of the paper.

Cancer-targeted PEDF-DNA therapy for metastatic colorectal cancer

Colorectal cancer (CRC) is a major cause of cancer-related mortality worldwide. Moreover, metastasis is one of the main causes of death in CRC patients. Nanotechnology-based gene therapy has shown significant therapeutic benefits in recent clinical trials for cancer treatment. Recent studies have shown that pigment epithelium-derived factor (PEDF) protein can inhibit tumor growth and metastasis by anti-angiogenesis and pro-apoptosis. In this study, we prepared a PEDF-DNA-loaded liposome for cancer-targeted gene therapy for metastatic CRC using an iRGD peptide. Our results showed that cancer-targeted PEDF-DNA liposomes (R-LP/PEDF) exhibited enhanced inhibitory effects on invasion, migration, and pro-apoptosis of CRC cells in vitro. In addition, it reduced metastasis tumor nodules in lung and prolonged the survival time in a mouse model of metastatic CRC.