Role of Dusp6 Phosphatase as a Tumor Suppressor in Non-Small Cell Lung Cancer

DUSP6 regulates Notch1 signalling in colorectal cancer

Notch1 plays various roles in cancer development, and Notch1-induced transactivation is controlled by phosphorylation of its cleaved intracellular domain. However, it is unclear whether there are phosphatases capable of dephosphorylating the cleaved Notch1 transmembrane/intracellular region (NTM) to regulate its function. Here, we show that DUSP6 can function as a phosphatase for Notch1, thereby regulating NTM stability and transcriptional activity, thus influencing colorectal cancer (CRC) development. In human CRC cells, elevated DUSP6 expression correlates with increased NTM levels, leading to enhanced CRC cell proliferation both in vitro and in vivo. High tumoral DUSP6 protein expression is associated with poorer overall CRC patient survival. In mice, DUSP6 deficiency results in reduced CRC development. Mechanistically, DUSP6 dephosphorylates phospho-Y2116, which in turn reduces NTM ubiquitination, leading to increased NTM stability and transcriptional activity. As a result, the expression of Notch1-targeted proliferation genes is increased to promote tumour cell growth.

Molecular and functional landscape of malignant serous effusions for precision oncology

Personalized treatment for patients with advanced solid tumors critically depends on the deep characterization of tumor cells from patient biopsies. Here, we comprehensively characterize a pan-cancer cohort of 150 malignant serous effusion (MSE) samples at the cellular, molecular, and functional level. We find that MSE-derived cancer cells retain the genomic and transcriptomic profiles of their corresponding primary tumors, validating their use as a patient-relevant model system for solid tumor biology. Integrative analyses reveal that baseline gene expression patterns relate to global ex vivo drug sensitivity, while high-throughput drug-induced transcriptional changes in MSE samples are indicative of drug mode of action and acquired treatment resistance. A case study exemplifies the added value of multi-modal MSE profiling for patients who lack genetically stratified treatment options. In summary, our study provides a functional multi-omics view on a pan-cancer solid tumor cohort and underlines the feasibility and utility of MSE-based precision oncology.

PRSS50-mediated inhibition of MKP3/ERK signaling is crucial for meiotic progression and sperm quality

Serine protease 50 (PRSS50/TSP50) is highly expressed in spermatocytes. Our study investigated its role in testicular development and spermatogenesis. Initially, PRSS50 knockdown was observed to impair DNA synthesis in spermatocytes. To further explore this, we generated PRSS50 knockout ( Prss50 -/- ) mice ( Mus musculus), which exhibited abnormal spermatid nuclear compression and reduced male fertility. Furthermore, dysplastic seminiferous tubules and decreased sex hormones were observed in 4-week-old Prss50 -/- mice, accompanied by meiotic progression defects and increased apoptosis of spermatogenic cells. Mechanistic analysis indicated that PRSS50 deletion resulted in increased phosphorylation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and elevated levels of MAP kinase phosphatase 3 (MKP3), a specific ERK antagonist, potentially accounting for testicular dysplasia in adolescent Prss50 -/- mice. Taken together, these findings suggest that PRSS50 plays an important role in testicular development and spermatogenesis, with the MKP3/ERK signaling pathway playing a significant role in this process.

Environmental Exposure to Persistent Organic Pollutants and Its Association with Endometriosis Risk: Implications in the Epithelial-Mesenchymal Transition Process

We aimed to explore the relationship of adipose tissue concentrations of some persistent organic pollutants (POPs) with the risk of endometriosis and the endometriotic tissue expression profile of genes related to the endometriosis-related epithelial-mesenchymal transition (EMT) process. This case-control study enrolled 109 women (34 cases and 75 controls) between January 2018 and March 2020. Adipose tissue samples and endometriotic tissues were intraoperatively collected to determine concentrations of nine POPs and the gene expression profiles of 36 EMT-related genes, respectively. Associations of POPs with endometriosis risk were explored with multivariate logistic regression, while the relationship between exposure and gene expression profiles was assessed through Spearman correlation or Mann-Whitney U tests. After adjustment, increased endometriosis risk was associated with p,p'-DDT, PCB-180, and ΣPCBs. POP exposure was also associated with reduced gene expression levels of the CLDN7 epithelial marker and increased levels of the ITGB2 mesenchymal marker and a variety of EMT promoters (HMGA1, HOXA10, FOXM1, DKK1, CCR1, TNFRSF1B, RRM2, ANG, ANGPT1, and ESR1). Our findings indicate that exposure to POPs may increase the risk of endometriosis and might have a role in the endometriosis-related EMT development, contributing to the disease onset and progression. Further studies are warranted to corroborate these findings.

Comprehensive analysis of circulating cell-free RNAs in blood for diagnosing non-small cell lung cancer

Early screening and detection of non-small cell lung cancer (NSCLC) is crucial due to the significantly low survival rate in advanced stages. Blood-based liquid biopsy is non-invasive test to assistant disease diagnosis, while cell-free RNA is one of the promising biomarkers in blood. However, the disease related signatures have not been explored completely for most cell-free RNA transcriptome sequencing (cfRNA-Seq) datasets. To address this gap, we developed a comprehensive cfRNA-Seq pipeline for data analysis and constructed a machine learning model to facilitate noninvasive early diagnosis of NSCLC. The results of our study have demonstrated the identification of differential mRNA, lncRNAs and miRNAs from cfRNA-Seq, which have exhibited significant association with development and progression of lung cancer. The classifier based on gene expression signatures achieved an impressive area under the curve (AUC) of up to 0.9, indicating high specificity and sensitivity in both cross-validation and independent test. Furthermore, the analysis of T cell and B cell immune repertoire extracted from cfRNA-Seq have provided insights into the immune status of cancer patients, while the microbiome analysis has revealed distinct bacterial and viral profiles between NSCLC and normal samples. In our future work, we aim to validate the existence of cancer associated T cell receptors (TCR)/B cell receptors (BCR) and microorganisms, and subsequently integrate all identified signatures into diagnostic model to improve the prediction accuracy. This study not only provided a comprehensive analysis pipeline for cfRNA-Seq dataset but also highlights the potential of cfRNAs as promising biomarkers and models for early NSCLC diagnosis, emphasizing their importance in clinical settings.

mRNA markers associated with malignant pleural effusion

Malignant pleural effusions (MPE) commonly result from malignant tumors and represent advanced-stage cancers. Thus, in clinical practice, early recognition of MPE is valuable. However, the current diagnosis of MPE is based on pleural fluid cytology or histologic analysis of pleural biopsies with a low diagnostic rate. This research aimed to assess the diagnostic ability of eight previously identified Non-Small Cell Lung Cancer (NSCLC)-associated genes for MPE. In the study, eighty-two individuals with pleural effusion were recruited. There were thirty-three patients with MPE and forty-nine patients with benign transudate. mRNA was isolated from the pleural effusion and amplified by Quantitative real-time PCR. The logistic models were further applied to evaluate the diagnostic performance of those genes. Four significant MPE-associated genes were discovered in our study, including Dual-specificity phosphatase 6 (DUSP6), MDM2 proto-oncogene (MDM2), Ring finger protein 4 (RNF4), and WEE1 G2 Checkpoint Kinase (WEE1). Pleural effusion with higher expression levels of MDM2 and WEE1 and lower expression levels of RNF4 and DUSP6 had a higher possibility of being MPE. The four-gene model had an excellent performance distinguishing MPE and benign pleural effusion, especially for pathologically negative effusions. Therefore, the gene combination is a suitable candidate for MPE screening in patients with pleural effusion. We also identified three survival-associated genes, WEE1, Neurofibromin 1 (NF1), and DNA polymerase delta interacting protein 2 (POLDIP2), which could predict the overall survival of patients with MPE.

Identification of AGR2 Gene-Specific Expression Patterns Associated with Epithelial-Mesenchymal Transition

The TGF-β signaling pathway is involved in numerous cellular processes, and its deregulation may result in cancer development. One of the key processes in tumor progression and metastasis is epithelial to mesenchymal transition (EMT), in which TGF-β signaling plays important roles. Recently, AGR2 was identified as a crucial component of the cellular machinery responsible for maintaining the epithelial phenotype, thereby interfering with the induction of mesenchymal phenotype cells by TGF-β effects in cancer. Here, we performed transcriptomic profiling of A549 lung cancer cells with CRISPR-Cas9 mediated AGR2 knockout with and without TGF-β treatment. We identified significant changes in transcripts associated with focal adhesion and eicosanoid production, in particular arachidonic acid metabolism. Changes in transcripts associated with the focal adhesion pathway were validated by RT-qPCR of COL4A1, COL4A2, FLNA, VAV3, VEGFA, and VINC mRNAs. In addition, immunofluorescence showed the formation of stress fibers and vinculin foci in cells without AGR2 and in response to TGF-β treatment, with synergistic effects observed. These findings imply that both AGR2 downregulation and TGF-β have a role in focal adhesion formation and cancer cell migration and invasion. Transcripts associated with arachidonic acid metabolism were downregulated after both AGR2 knockout and TGF-β treatment and were validated by RT-qPCR of GPX2, PTGS2, and PLA2G4A. Since PGE₂ is a product of arachidonic acid metabolism, its lowered concentration in media from AGR2-knockout cells was confirmed by ELISA. Together, our results demonstrate that AGR2 downregulation and TGF-β have an essential role in focal adhesion formation; moreover, we have identified AGR2 as an important component of the arachidonic acid metabolic pathway.

A positive feedback loop of ARF6 activates ERK1/2 signaling pathway via DUSP6 silencing to promote pancreatic cancer progression

ERK1/2 are essential proteins mediating mitogen-activated protein kinase signaling downstream of RAS in pancreatic adenocarcinoma (PDAC). Our previous study reveals that ARF6 plays a positive regulatory role in ERK1/2 pathway in a feedback loop manner. A significant part of the literature on ARF6 has emphasized its oncogenic effect as an essential downstream molecule of ERK1/2, and no research has been done on the regulation mechanisms of the feedback loop between ARF6 and the ERK1/2 signaling pathway. In the present study, we explore the gene network downstream of ARF6 and find that DUSP6 may be the critical signal molecule in the positive feedback loop between ARF6 and ERK1/2. Specifically, to elucidate the negative correlations between ARF6 and DUSP6 in pancreatic cancer, we examine their expressions in pancreatic cancer tissues by immunohistochemical staining. Then the impact of DUSP6 on the proliferation and apoptosis of PDAC cells are investigated by gain-of-function and loss-of-function approaches. Mechanism explorations uncover that ARF6 suppresses the expression of DUSP6, which is responsible for the dephosphorylation of ERK1/2. Altogether, these results indicate that DUSP6 plays a tumor-suppressive role and acts as an intermediate molecule between ARF6 and ERK1/2 in PDAC cells, thereby forming a positive feedback loop.

Construction and validation of a novel prediction system for detection of overall survival in lung cancer patients

BACKGROUND

Many factors have an aberrant effect on the overall survival of lung cancer (LC) patients. In recent years, remarkable progress has been made in immunotherapy, targeted treatment, and promising biomarkers. However, the available treatments and diagnostic methods are not specific for all patients.

AIM

To establish a system for predicting poor survival in patients with LC.

METHODS

The expression matrix and clinical information for this study were obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases. After the differential analysis of all screened genes, weighted gene coexpression network analysis was performed to analyze hub genes related to patient survival. A logistic regression model was used to construct the scoring system. The expression of the hub genes was verified by performing quantitative reverse transcription-polymerase chain reaction.

RESULTS

A total of 5007 differentially expressed genes were selected for the Weighted Gene Co-expression Network Analysis algorithm. We found that the turquoise module showed the highest correlation with patient prognosis. The gene module with the greatest positive correlation with patient survival was located in the turquoise area. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses performed for the genes contained in the turquoise module indicated the potential roles of the selected genes in the regulation of LC development. In addition, protein–protein interaction analysis was performed to screen hub genes, which identified 100 hub genes located in the core area of the network. We then intersected the 100 hub genes with 75 key genes sorted by module members to identify real hub genes associated with prognosis. Forty-one genes were finally selected. We then used a logistic regression model to determine 11 independent risk genes, namely CCNB2, CDC20, CENPO, FOXM1, HJURP, NEK2, OIP5, PLK1, PRC1, SKA1, UBE2C and SPARC.

CONCLUSION

We constructed a predictive model based on 11 independent risk genes to establish a system predicting the survival status of patients with non-small-cell lung carcinoma.

ALV-miRNA-p19-01 Promotes Viral Replication via Targeting Dual Specificity Phosphatase 6

MicroRNAs (miRNAs) are a group of regulatory noncoding RNAs, serving as major regulators with a sequence-specific manner in multifarious biological processes. Although a series of viral families have been proved to encode miRNAs, few reports were available regarding the function of ALV-J-encoded miRNA. Here, we reported a novel miRNA (designated ALV-miRNA-p19-01) in ALV-J-infected DF-1 cells. We found that ALV-miRNA-p19-01 is encoded by the genome of the ALV-J SCAU1903 strain (located at nucleotides site 779 to 801) in a classic miRNA biogenesis manner. The transfection of DF-1 cells with ALV-miRNA-p19-01 enhanced ALV-J replication, while the blockage of ALV-miRNA-p19-01 suppressed ALV-J replication. Furthermore, our data showed that ALV-miRNA-p19-01 promotes ALV-J replication by directly targeting the cellular gene dual specificity phosphatase 6 through regulating ERK2 activity.

Clinical Significance and Regulation of ERK5 Expression and Function in Cancer

Extracellular signal-regulated kinase 5 (ERK5) is a unique kinase among MAPKs family members, given its large structure characterized by the presence of a unique C-terminal domain. Despite increasing data demonstrating the relevance of the ERK5 pathway in the growth, survival, and differentiation of normal cells, ERK5 has recently attracted the attention of several research groups given its relevance in inflammatory disorders and cancer. Accumulating evidence reported its role in tumor initiation and progression. In this review, we explore the gene expression profile of ERK5 among cancers correlated with its clinical impact, as well as the prognostic value of ERK5 and pERK5 expression levels in tumors. We also summarize the importance of ERK5 in the maintenance of a cancer stem-like phenotype and explore the major known contributions of ERK5 in the tumor-associated microenvironment. Moreover, although several questions are still open concerning ERK5 molecular regulation, different ERK5 isoforms derived from the alternative splicing process are also described, highlighting the potential clinical relevance of targeting ERK5 pathways.

Biphasic Regulation of Mitogen-Activated Protein Kinase Phosphatase 3 in Hypoxic Colon Cancer Cells

Hypoxia, or low oxygen tension, is a hallmark of the tumor microenvironment. The hypoxia-inducible factor-1α (HIF-1α) subunit plays a critical role in the adaptive cellular response of hypoxic tumor cells to low oxygen tension by activating gene-expression programs that control cancer cell metabolism, angiogenesis, and therapy resistance. Phosphorylation is involved in the stabilization and regulation of HIF-1α transcriptional activity. HIF-1α is activated by several factors, including the mitogen-activated protein kinase (MAPK) superfamily. MAPK phosphatase 3 (MKP-3) is a cytoplasmic dual-specificity phosphatase specific for extracellular signal-regulated kinase 1/2 (Erk1/2). Recent evidence indicates that hypoxia increases the endogenous levels of both MKP-3 mRNA and protein. However, its role in the response of cells to hypoxia is poorly understood. Herein, we demonstrated that small-interfering RNA (siRNA)-mediated knockdown of MKP-3 enhanced HIF-1α (not HIF-2α) levels. Conversely, MKP-3 overexpression suppressed HIF-1α (not HIF-2α) levels, as well as the expression levels of hypoxia-responsive genes (LDHA, CA9, GLUT-1, and VEGF), in hypoxic colon cancer cells. These findings indicated that MKP-3, induced by HIF-1α in hypoxia, negatively regulates HIF-1α protein levels and hypoxia-responsive genes. However, we also found that long-term hypoxia (>12 h) induced proteasomal degradation of MKP-3 in a lactic acid-dependent manner. Taken together, MKP-3 expression is modulated by the hypoxic conditions prevailing in colon cancer, and plays a role in cellular adaptation to tumor hypoxia and tumor progression. Thus, MKP-3 may serve as a potential therapeutic target for colon cancer treatment.

Role of Protein Tyrosine Phosphatase in Regulation of Cell Signaling Cascades Affecting Tumor Cell Growth: A Future Perspective as Anti- Cancer Drug Target

Protein Tyrosine Phosphatase (PTP) superfamily is a key enzyme involved in the regulation of growth-related cell signaling cascades, such as the RAS/MAPK pathway, that directly affect cancer cell growth and metastasis. Several studies have indicated that the drug resistance observed in several late-stage tumors might also be affected by the levels of PTP in the cell. Hence, these phosphatases have been in the limelight for the past few decades as potential drug-targets and several promising drug candidates have been developed, even though none of these drugs have reached the market yet. In this review, we explore the potential of PTP as a viable anti-cancer drug target by studying PTPs, their regulation of several key cancer cell signaling pathways and how their levels affect various types of cancer. Furthermore, we present the current scenario of PTP as a molecular target and the various challenges faced in the development of PTP-targeting anti-cancer drugs.

The emerging roles of dual-specificity phosphatases and their specific characteristics in human cancer

Reversible phosphorylation of proteins, controlled by kinases and phosphatases, is involved in various cellular processes. Dual-specificity phosphatases (DUSPs) can dephosphorylate phosphorylated serine, threonine and tyrosine residues. This family consists of 61 members, 44 of which have been identified in human, and these 44 members are classified into six subgroups, the phosphatase and tensin homolog (PTEN) protein phosphatases (PTENs), mitogen-activated protein kinase phosphatases (MKPs), atypical DUSPs, cell division cycle 14 (CDC14) phosphatases (CDC14s), slingshot protein phosphatases (SSHs), and phosphatases of the regenerating liver (PRLs). Growing evidence has revealed dysregulation of DUSPs as one of the common phenomenons and highlighted their key roles in human cancers. Furthermore, their differential expression may be a potential biomarker for tumor prognosis. Despite this, there are still many unstudied members of DUSPs need to further explore their precise roles and mechanism in cancers. Most importantly, the systematic review is very limited on the functional/mechanistic characteristics and clinical application of DUSPs at present. In this review, the structures, functions and underlying mechanisms of DUSPs are systematically reviewed, and the molecular and functional characteristics of DUSPs in different tumor types according to the current researches are summarized. In addition, the potential roles of the unstudied members and the possible different mechanisms of DUSPs in cancer are discussed and classified based on homology alignment and structural domain analyses. Moreover, the specific characteristics of their expression and prognosis are further determined in more than 30 types of human cancers by using the online databases. Finally, their potential application in precise diagnosis, prognosis and treatment of different types of cancers, and the main possible problems for the clinical application at present are prospected.

Network pharmacology-based study to explore the mechanism of the Yiqi Gubiao pill in lung cancer treatment

Lung cancer (LC) has been one of the most prevalent and fatal malignancies in the past 5 years. Yiqi Gubiao pills have a good clinical effect against LC. However, their complex composition limits proper understanding of their pharmacological mechanism. Therefore, the present study aimed to systemically explore the underlying mechanisms of Yiqi Gubiao pills in treatment of LC. The network pharmacology approach was employed to identify the active ingredients and LC targets associated with Yiqi Gubiao pills. Prediction of potential active ingredients and action targets was then conducted through protein-protein interaction (PPI), Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses. In vitro experiments were then performed to further verify the mechanism of action of Yiqi Gubiao pills, revealing that the anti-LC effects were mediated by regulating the expression of IL6, TP53, albumin (ALB), MAPK3 and AKT1. In total, 102 active ingredients and 229 targets of Yiqi Gubiao pills were identified. The PPI network further revealed that AKT1, TP53, ALB, IL6 and MAPK3 were the top five hub genes associated with LC treatment. Targets of the Yiqi Gubiao pills were mainly enriched in the PI3K-Akt and Advanced glycation end products (AGE)-receptors for AGEs (RAGE) signaling pathways. Overall, network pharmacology deciphered the active ingredients and potential targets of the Yiqi Gubiao pills. Yiqi Gubiao pills partially inhibited the progression of LC by regulating the expression of hub genes (AKT1, TP53, ALB, IL6 and MAPK3) through the PI3K-Akt and AGE-RAGE signaling pathways. The findings of the present study may provide a theoretical basis for the clinical application of Yiqi Gubiao pills in LC treatment.

Molecular Mechanisms of Epithelial to Mesenchymal Transition Regulated by ERK5 Signaling

Extracellular signal-regulated kinase (ERK5) is an essential regulator of cancer progression, tumor relapse, and poor patient survival. Epithelial to mesenchymal transition (EMT) is a complex oncogenic process, which drives cell invasion, stemness, and metastases. Activators of ERK5, including mitogen-activated protein kinase 5 (MEK5), tumor necrosis factor α (TNF-α), and transforming growth factor-β (TGF-β), are known to induce EMT and metastases in breast, lung, colorectal, and other cancers. Several downstream targets of the ERK5 pathway, such as myocyte-specific enhancer factor 2c (MEF2C), activator protein-1 (AP-1), focal adhesion kinase (FAK), and c-Myc, play a critical role in the regulation of EMT transcription factors SNAIL, SLUG, and β-catenin. Moreover, ERK5 activation increases the release of extracellular matrix metalloproteinases (MMPs), facilitating breakdown of the extracellular matrix (ECM) and local tumor invasion. Targeting the ERK5 signaling pathway using small molecule inhibitors, microRNAs, and knockdown approaches decreases EMT, cell invasion, and metastases via several mechanisms. The focus of the current review is to highlight the mechanisms which are known to mediate cancer EMT via ERK5 signaling. Several therapeutic approaches that can be undertaken to target the ERK5 pathway and inhibit or reverse EMT and metastases are discussed.

Identification of novel transcription factor-microRNA-mRNA co-regulatory networks in pulmonary large-cell neuroendocrine carcinoma

Background

Large cell neuroendocrine carcinoma (LCNEC) of the lung is a rare neuroendocrine neoplasm. Previous studies have shown that microRNAs (miRNAs) are widely involved in tumor regulation through targeting critical genes. However, it is unclear which miRNAs play vital roles in the pathogenesis of LCNEC, and how they interact with transcription factors (TFs) to regulate cancer-related genes.

Methods

To determine the novel TF-miRNA-target gene feed-forward loop (FFL) model of LCNEC, we integrated multi-omics data from Gene Expression Omnibus (GEO), Transcriptional Regulatory Relationships Unraveled by Sentence-Based Text Mining (TRRUST), Transcriptional Regulatory Element Database (TRED), and The experimentally validated microRNA-target interactions database (miRTarBase database). First, expression profile datasets for mRNAs (GSE1037) and miRNAs (GSE19945) were downloaded from the GEO database. Overlapping differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were identified through integrative analysis. The target genes of the FFL were obtained from the miRTarBase database, and the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were performed on the target genes. Then, we screened for key miRNAs in the FFL and performed gene regulatory network analysis based on key miRNAs. Finally, the TF-miRNA-target gene FFLs were constructed by the hypergeometric test.

Results

A total of 343 DEGs and 60 DEMs were identified in LCNEC tissues compared to normal tissues, including 210 down-regulated and 133 up-regulated genes, and 29 down-regulated and 31 up-regulated miRNAs. Finally, the regulatory network of TF-miRNA-target gene was established. The key regulatory network modules included ETS1-miR195-CD36, TAOK1-miR7-1-3P-GRIA1, E2F3-miR195-CD36, and TEAD1-miR30A-CTHRC1.

Conclusions

We constructed the TF-miRNA-target gene regulatory network, which is helpful for understanding the complex LCNEC regulatory mechanisms.

MicroRNA-211 Modulates the DUSP6-ERK5 Signaling Axis to Promote BRAFV600E-Driven Melanoma Growth In Vivo and BRAF/MEK Inhibitor Resistance

MicroRNAs (miRs) are important posttranscriptional regulators of cell fate in both normal and disease states. miR-211 has previously been shown to be a direct regulator of metabolism in BRAF^V600E-mutant melanoma cells in vitro. Here, we report that miR-211 expression promotes the aggressive growth of BRAF^V600E-mutant melanoma xenografts in vivo. miR-211 promoted proliferation through the posttranscriptional activation of extracellular signal-regulated kinase (ERK) 5 signaling, which has recently been implicated in the resistance to BRAF and MAPK/ERK kinase inhibitors. We therefore examined whether miR-211 similarly modulated melanoma resistance to the BRAF inhibitor vemurafenib and the MAPK/ERK kinase inhibitor cobimetinib. Consistent with this model, miR-211 expression increased melanoma cell resistance to both the inhibitors, and this resistance was associated with an increased ERK5 phosphorylation. miR-211 mediates these effects by directly inhibiting the expression of DUSP6, an ERK5 pathway-specific phosphatase and now shown to be an miR-211 target gene. These results dissect the role of the miR-211-DUSP6-ERK5 axis in melanoma tumor growth and suggest a mechanism for the development of drug-resistant tumors and a target for overcoming resistance.

ZNF251 promotes the progression of lung cancer by activating ERK signaling

Aberrant activation of ERK signaling is a hallmark of lung cancer. Although constitutively activating mutations of EGFR and KRAS contribute to the hyperactivation of ERK1/2, other mechanisms remain elusive. In this study, the zinc finger protein ZNF251 was found to be upregulated in clinical lung cancer samples, and it promoted the growth of lung cancer cells and the growth of primary lung KPC cells from mouse models (Ad-Cre, KrasG12D , and P53f/f ). In studying the molecular mechanism, ZNF251 was found to inhibit the expression of dual-specificity phosphatase 6, a negative regulator of ERK activation, by directly binding to its promoter region. Taken together, our data indicate the tumor-promoting effects of ZNF251 in lung cancer and suggest that ZNF251 is a therapeutic target.

Knockdown of TRIM37 Promotes Apoptosis and Suppresses Tumor Growth in Gastric Cancer by Inactivation of the ERK1/2 Pathway

OBJECTIVE

Gastric cancer (GC), a malignant tumor of the gastric mucosa, is the second leading cause of cancer deaths worldwide. Although the incidence and mortality of gastric cancer have been reduced in the US and elsewhere, it is still a major public health concern. In this study, we attempted to investigate the function of tripartite motif-containing protein 37 (TRIM37) in GC cell lines in order to propose a new therapy for GC.

METHODS

The expression of TRIM37 in GC patients and cell lines was detected by immunohistochemistry, real-time PCR and Western blotting analysis. After TRIM37 knockdown or overexpression, the cell cycle, proliferation and apoptosis, as well as the expression of related proteins, were detected. In addition, in vivo experiments on nude mice were performed.

RESULTS

We found that TRIM37 expression was significantly elevated in tumor tissues of GC patients and GC cell lines, and patients with high expression of TRIM37 had a poor prognosis. Knockdown of TRIM37 in GC cells significantly inhibited cell proliferation and cell cycle progression, promoted apoptosis, increased cleaved caspase 3 and decreased c-myc and phosphorylation of protein kinase 1/2 (p-ERK1/2). Effects of TRIM37 overexpression were opposite to that of TRIM37 knockdown and were potently attenuated by an ERK1/2 inhibitor. In addition, an ERK1/2 agonist increased TRIM37 and p-ERK1/2 in a dose-dependent manner, and TRIM37 knockdown potently attenuated EGF-induced cell proliferation and expression of TRIM37 and p-ERK1/2. Interestingly, we found that TRIM37 overexpression did not affect the mRNA level of dual-specificity phosphatase 6 (DUSP6), but reduced its protein level in GC cells. Co-immunoprecipitation (Co-IP) analyses revealed that TRIM37 interacted with DUSP6, and TRIM37 overexpression enhanced DUSP6 ubiquitination in GC cells. In vivo experiments on nude mice showed the inhibitory effect of TRIM37 knockdown on tumor growth.

CONCLUSION

These findings suggest that TRIM37 may act as an oncogene in the growth of GC cells and illustrate its potential function as a target in the treatment of GC.

LRIG3 represses cell motility by inhibiting slug via inactivating ERK signaling in human colorectal cancer

Metastasis is responsible for 90% of colorectal cancer (CRC)-related deaths. In the present study, we identified a novel key regulator of CRC metastasis, leucine-rich repeats and immunoglobulin-like domains protein 3 (LRIG3), which was significantly decreased in CRC tissues and cell lines. Downregulation of LRIG3 was attributed to copy number loss and promoter hypermethylation. Low LRIG3 expression was positively correlated with metastatic clinical features and shorter survival time. Functional experiments showed that knockout of LRIG3 markedly enhanced CRC cell migration and invasion ability, whereas reintroduction of LRIG3 exerted the opposite effects. Regarding the mechanism, LRIG3 could facilitate the binding of DUSP6 to ERK1/2, resulting in the dephosphorylation of ERK1/2 and subsequently downregulation of slug, an epithelial-to-mesenchymal transition trigger, thereby constraining CRC cell motility. Importantly, LRIG3 expression was strongly negatively correlated with slug or p-ERK1/2 expression in CRC tissues. Collectively, our data suggest that LRIG3 is a novel suppressor of CRC metastasis, reactivation of LRIG3 may be a promising therapeutic approach for metastatic CRC patients.