Regulatory Roles of MAPK Phosphatases in Cancer

Deficiency of smooth muscle cell ILF3 alleviates intimal hyperplasia via HMGB1 mRNA degradation-mediated regulation of the STAT3/DUSP16 axis

Intimal hyperplasia is a complicated pathophysiological phenomenon attributable to in-stent restenosis, and the underlying mechanism remains unclear. Interleukin enhancer-binding factor 3 (ILF3), a double-stranded RNA-binding protein involved in regulating mRNA stability, has been recently demonstrated to assume a crucial role in cardiovascular disease; nevertheless, its impact on intimal hyperplasia remains unknown. In current study, we used samples of human restenotic arteries and rodent models of intimal hyperplasia, we found that vascular smooth muscle cell (VSMC) ILF3 expression was markedly elevated in human restenotic arteries and murine ligated carotid arteries. SMC-specific ILF3 knockout mice significantly suppressed injury induced neointimal formation. In vitro, platelet-derived growth factor type BB (PDGF-BB) treatment elevated the level of VSMC ILF3 in a dose- and time-dependent manner. ILF3 silencing markedly inhibited PDGF-BB-induced phenotype switching, proliferation, and migration in VSMCs. Transcriptome sequencing and RNA immunoprecipitation sequencing depicted that ILF3 maintained its stability upon binding to the mRNA of the high-mobility group box 1 protein (HMGB1), thereby exerting an inhibitory effect on the transcription of dual specificity phosphatase 16 (DUSP16) through enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3). Therefore, the results both in vitro and in vivo indicated that the loss of ILF3 in VSMC ameliorated neointimal hyperplasia by regulating the STAT3/DUSP16 axis through the degradation of HMGB1 mRNA. Our findings revealed that vascular injury activates VSMC ILF3, which in turn promotes intima formation. Consequently, targeting specific VSMC ILF3 may present a potential therapeutic strategy for ameliorating cardiovascular restenosis.

DUSP4 maintains the survival and LSD1 protein stability in esophageal squamous cell carcinoma cells by inhibiting JNK signaling-dependent autophagy

DUSP4 is a biomarker of esophageal squamous cell carcinoma (ESCC), which is responsible for the prognosis in ESCC. However, the underlying mechanism of DUSP4-regulated ESCC carcinogenesis is unknown. As a negative regulator of JNK, DUSP4 can inhibit autophagy, which contributes to tumorigenesis. This study aimed to explore the role of autophagy in DUSP4-regulated ESCC carcinogenesis. Our results showed that DUSP4 overexpression inhibited autophagy and promoted LSD1 protein expression in ESCC cells, while DUSP4 silencing showed the opposite effects. However, DUSP4 overexpression and silencing did not affect LSD1 mRNA expression. But the regulatory ability of DUSP4 overexpression on autophagy, death level, and LSD1 protein was reversed by rapamycin. In addition, DUSP4 overexpression inhibited JNK and Bcl2 phosphorylation and the dissociation of Bcl2-Beclin1 complex, while DUSP4 silencing promoted JNK and Bcl2 phosphorylation. Moreover, the regulatory ability of DUSP4 overexpression on autophagy, death, and LSD1 protein was reversed by JNK activator anisomycin. The xenograft assays also showed that DUSP4 overexpression-promoted ESCC tumor growth in vivo and LC3II and LSD1 protein expression in tumor tissues were reversed by rapamycin or anisomycin. Overall, DUSP4 inhibits Bcl2-Beclin1-autophagy signal transduction through the negative regulation of JNK, thus suppressing autophagic death and the autophagic degradation of LSD1 in ESCC, by which DUSP4 promotes ESCC carcinogenesis.

Dual specific phosphatase 4 suppresses ferroptosis and enhances sorafenib resistance in hepatocellular carcinoma

AIMS

This investigation aims to elucidate the mechanism underlying sorafenib-induced ferroptosis in hepatocellular carcinoma (HCC).

METHODS

The role of dual specificity phosphatase 4 (DUSP4) in sorafenib-treated HCC was investigated using comprehensive assessments both in vitro and in vivo, including Western blotting, qRT-PCR, cell viability assay, lipid reactive oxygen species (ROS) assay, immunohistochemistry, and xenograft tumor mouse model. Additionally, label-free quantitative proteomics was employed to identify potential proteins associated with DUSP4.

RESULTS

Our study revealed that suppression of DUSP4 expression heightens the susceptibility of HCC cells to ferroptosis inducers, specifically sorafenib and erastin, in both in vitro and in vivo settings. Furthermore, we identified DUSP4-mediated regulation of key ferroptosis-related markers, such as ferritin light chain (FTL) and ferritin heavy chain 1 (FTH1). Notably, label-free quantitative proteomics unveiled the phosphorylation of threonine residue T148 on YTH Domain Containing 1 (YTHDC1) by DUSP4. Further investigations unraveled that YTHDC1, functioning as an mRNA nuclear export regulator, is a direct target of DUSP4, orchestrating the subcellular localization of FTL and FTH1 mRNAs. Significantly, our study highlights a strong correlation between elevated DUSP4 expression and sorafenib resistance in HCC.

CONCLUSIONS

Our findings introduce DUSP4 as a negative regulator of sorafenib-induced ferroptosis. This discovery opens new avenues for the development of ferroptosis-based therapeutic strategies tailored for HCC treatment.

Role of Mitogen-Activated Protein (MAP) Kinase Pathways in Metabolic Diseases

Physiological processes that govern the normal functioning of mammalian cells are regulated by a myriad of signalling pathways. Mammalian mitogen-activated protein (MAP) kinases constitute one of the major signalling arms and have been broadly classified into four groups that include extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and ERK5. Each signalling cascade is governed by a wide array of external and cellular stimuli, which play a critical part in mammalian cells in the regulation of various key responses, such as mitogenic growth, differentiation, stress responses, as well as inflammation. This evolutionarily conserved MAP kinase signalling arm is also important for metabolic maintenance, which is tightly coordinated via complicated mechanisms that include the intricate interaction of scaffold proteins, recognition through cognate motifs, action of phosphatases, distinct subcellular localisation, and even post-translational modifications. Aberration in the signalling pathway itself or their regulation has been implicated in the disruption of metabolic homeostasis, which provides a pathophysiological foundation in the development of metabolic syndrome. Metabolic syndrome is an umbrella term that usually includes a group of closely associated metabolic diseases such as hyperglycaemia, hyperlipidaemia, and hypertension. These risk factors exacerbate the development of obesity, diabetes, atherosclerosis, cardiovascular diseases, and hepatic diseases, which have accounted for an increase in the worldwide morbidity and mortality rate. This review aims to summarise recent findings that have implicated MAP kinase signalling in the development of metabolic diseases, highlighting the potential therapeutic targets of this pathway to be investigated further for the attenuation of these diseases.

PIWI-interacting RNA-YBX1 inhibits proliferation and metastasis by the MAPK signaling pathway via YBX1 in triple-negative breast cancer

Breast cancer is the second leading cause of death in women worldwide, with triple-negative breast cancer (TNBC) having the worst prognosis. Although there are numerous studies on TNBC, there is no effective treatment for it, and it is still a major problem today. Studies on PIWI-interacting RNAs (piRNAs) are increasing and investigating the mechanism of piRNAs in the proliferation and metastasis of TNBC may lead to new potential treatment targets. Here, we identified a novel piRNA, piR-YBX1, which was downregulated in TNBC compared to matched normal breast tissue. Overexpression of piR-YBX1 significantly inhibited the proliferation, migration, invasion ability of TNBC cells both in vivo and in vitro. Mechanistically, piR-YBX1 could bind directly to mRNA of Y-box binding protein 1 (YBX1) and overexpression of piR-YBX1 downregulated YBX1 in both mRNA and protein levels, while the function of piR-YBX1 could be partly rescued by overexpression of YBX1. In addition, YBX1 could bind to RAF1 which is the key molecule in the MAPK signaling pathway, and overexpression of piR-YBX1 inhibited the p-MEK and p-ERK1/2, which can be reverted by YBX1. In conclusion, our findings discovered that the piR-YBX1/YBX1/MAPK axis suppresses the proliferation and metastasis of TNBC and therefore piR-YBX1 has the potential to be an effective therapeutic agent for breast cancer.

Investigating the therapeutic mechanism of Xiaotan Sanjie Formula for gastric cancer via network pharmacology and molecular docking: A review

Xiaotan Sanjie Formula (XTSJF), a traditional Chinese prescription, holds promising potential in addressing gastric cancer (GC). Despite this, the fundamental constituents and underlying mechanisms that define XTSJF's attributes remain enigmatic. Against this backdrop, this study endeavors to unravel the latent mechanisms driving XTSJF's impact on GC, leveraging the synergistic prowess of network pharmacology and molecular docking methodologies. To understand the potential mechanism of XTSJF against GC, this study used network pharmacology, molecular docking, and bioinformatics analytic methodologies. There are 135 active components where the active ingredients with a higher degree value are quercetin, β-sitosterol, naringenin, nobiletin, and kaempferol and 167 intersecting targets in which TP53, MAPK3, MAPK1, STAT3, and AKT1 were key targets were identified in XTSJF in the treatment of GC. According to GO and KEGG analyses, XTSJF is mostly involved in the positive control of transcription from the RNA polymerase II promoter, enzyme interaction, and other biological processes in GC. KEGG analysis shows that XTSJF treated GC primarily by regulating signaling pathways including the TNF, PI3K-Akt, and MAPK signaling pathways. According to the results of the PPI network and molecular docking, quercetin, β-sitosterol, naringenin, nobiletin, and kaempferol exhibit stronger affinity with TP53, MAPK3, MAPK1, STAT3, and AKT1. This study indicates the active components of XTSJF as well as its possible molecular mechanism against GC, and it serves as a foundation for future fundamental research.

From fetal tendon regeneration to adult therapeutic modalities: TGF-β3 in scarless healing

Tendon injuries are common disorders that can significantly impact people's lives. Unfortunately, the limited regenerative ability of tendons results in tissue healing in a scar-mediated manner. The current therapeutic strategies fail to fully recover the functions of the injured tendons, and as such, the conception of 'scarless healing' has gained prominent attention in the field of regenerative medicine. Interestingly, injured fetal tendons possess the capability to heal through regeneration, which builds an ideal blueprint for adult tendon regeneration. Studies have shown that fetal biochemical cues have the potential to improve adult tendon healing. Here we review the biological factors that contribute to fetal tendon regeneration and how manipulation of these biochemical cues in the adult tendon healing process could achieve regeneration.

In Vitro and In Silico Investigation of BCI Anticancer Properties and Its Potential for Chemotherapy-Combined Treatments

BACKGROUND

DUSP6 phosphatase serves as a negative regulator of MAPK kinases involved in numerous cellular processes. BCI has been identified as a potential allosteric inhibitor with anticancer activity. Our study was designed to test the anticancer properties of BCI in colon cancer cells, to characterize the effect of this compound on chemotherapeutics such as irinotecan and oxaliplatin activity, and to identify potential molecular targets for this inhibitor.

METHODS

BCI cytotoxicity, proapoptotic activity, and cell cycle distribution were investigated in vitro on three colon cancer cell lines (DLD1, HT-29, and Caco-2). In silico investigation was prepared to assess BCI drug-likeness and identify potential molecular targets.

RESULTS

The exposure of colorectal cancer cells with BCI resulted in antitumor effects associated with cell cycle arrest and induction of apoptosis. BCI exhibited strong cytotoxicity on DLD1, HT-29, and Caco-2 cells. BCI showed no significant interaction with irinotecan, but strongly attenuated the anticancer activity of oxaliplatin when administered together. Analysis of synergy potential further confirmed the antagonistic interaction between these two compounds. In silico investigation indicated CDK5 as a potential new target of BCI.

CONCLUSIONS

Our studies point to the anticancer potential of BCI but note the need for a precise mechanism of action.

mPFC DUSP1 mediates adolescent cocaine exposure-induced higher sensitivity to drug in adulthood

Adolescent cocaine abuse increases the risk for developing addiction in later life, but the underlying molecular mechanism remains poorly understood. Here, we establish adolescent cocaine-exposed (ACE) male mouse models. A subthreshold dose of cocaine (sdC) treatment, insufficient to produce conditioned place preference (CPP) in adolescent mice, induces CPP in ACE mice during adulthood, along with more activated CaMKII-positive neurons, higher dual specificity protein kinase phosphatase-1 (Dusp1) mRNA, lower DUSP1 activity, and lower DUSP1 expression in CaMKII-positive neurons in the medial prefrontal cortex (mPFC). Overexpressing DUSP1 in CaMKII-positive neurons suppresses neuron activity and blocks sdC-induced CPP in ACE mice during adulthood. On the contrary, depleting DUSP1 in CaMKII-positive neurons activates more neurons and further enhances sdC-induced behavior in ACE mice during adulthood. Also, ERK1/2 might be a downstream signal of DUSP1 in the process. Our findings reveal a role of mPFC DUSP1 in ACE-induced higher sensitivity to the drug in adult mice. DUSP1 might be a potential pharmacological target to predict or treat the susceptibility to addictive drugs caused by adolescent substance use.

Tumor Promoting Function of DUSP10 in Non-Small Cell Lung Cancer Is Associated With Tumor-Promoting Cytokines

Lung cancer, particularly non-small cell lung cancer (NSCLC) which contributes more than 80% to totally lung cancer cases, remains the leading cause of cancer death and the 5-year survival is less than 20%. Continuous understanding on the mechanisms underlying the pathogenesis of this disease and identification of biomarkers for therapeutic application and response to treatment will help to improve patient survival. Here we found that a molecule known as DUSP10 (also known as MAPK phosphatase 5) is oncogenic in NSCLC. Overexpression of DUSP10 in NSCLC cells resulted in reduced activation of ERK and JNK, but increased activation of p38, which was associated with increased cellular growth and migration. When inoculated in immunodeficient mice, the DUSP10-overexpression NSCLC cells formed larger tumors compared to control cells. The increased growth of DUSP10-overexpression NSCLC cells was associated with increased expression of tumor-promoting cytokines including IL-6 and TGFβ. Importantly, higher DUSP10 expression was associated with poorer prognosis of NSCLC patients. Therefore, DUSP10 could severe as a biomarker for NSCLC prognosis and could be a target for development of therapeutic method for lung cancer treatment.

KMU-191 Induces Apoptosis in Human Clear Cell Renal Cell Carcinoma Caki Cells Through Modulation of Bcl-xL, Mcl-1 (L), c-FLIP (L), and p53 Proteins

The anti-proliferative effects of a newly developed N3-acyl-N5-aryl-3,5-diaminoindazole analog, KMU-191, have been previously evaluated in various cancer cells. However, the detailed anti-cancer molecular mechanisms of KMU-191 remain unknown. In this study, we investigated anti-cancer mechanisms by which KMU-191 regulates apoptosis-related genes in human clear cell renal cell carcinoma Caki cells. KMU-191 induced poly ADP-ribose polymerase cleavage and caspase-dependent apoptosis. In addition, KMU-191 induced down-regulation of the long form of cellular FADD-like IL-1β-converting enzyme inhibitory protein (c-FLIP (L)) at the transcriptional level as well as that of long form of myeloid cell leukemia (Mcl-1 (L)) and B-cell lymphoma-extra large at the post-transcriptional level. Furthermore, KMU-191-induced apoptosis was closely associated with the Mcl-1 (L) down-regulation, but also partially associated with c-FLIP (L) down-regulation. In contrast, KMU-191 up-regulated p53, which is closely related to KMU-191-induced apoptosis. Although KMU-191 showed cytotoxicity of normal cells, it unusually did not induce cardiotoxicity. Taken together, these results suggest that a multi-target small molecule, N3-acyl-N5-aryl-3,5-diaminoindazole analog, KMU-191 is a potential anti-cancer agent that does not induce cardiotoxicity.

Integrating scRNA and bulk-RNA sequencing develops a cell senescence signature for analyzing tumor heterogeneity in clear cell renal cell carcinoma

Introduction

Cellular senescence (CS) plays a critical role in cancer development, including clear cell renal cell carcinoma (ccRCC). Traditional RNA sequencing cannot detect precise molecular composition changes within tumors. This study aimed to analyze cellular senescence's biochemical characteristics in ccRCC using single RNA sequencing (ScRNA-seq) and traditional RNA sequencing (Bulk RNA-seq).

Methods

Researchers analyzed the biochemical characteristics of cellular senescence in ccRCC using ScRNA-seq and Bulk RNA-seq. They combined these approaches to identify differences between malignant and non-malignant phenotypes in ccRCC across three senescence-related pathways. Genes from these pathways were used to identify molecular subtypes associated with senescence, and a new risk model was constructed. The function of the gene DUSP1 in ccRCC was validated through biological experiments.

Results

The combined analysis of ScRNA-seq and Bulk RNA-seq revealed significant differences between malignant and non-malignant phenotypes in ccRCC across three senescence-related pathways. Researchers identified genes from these pathways to identify molecular subtypes associated with senescence, constructing a new risk model. Different subgroups showed significant differences in prognosis level, clinical stage and grade, immune infiltration, immunotherapy, and drug sensitivity.

Discussion

Senescence signature markers are practical biomarkers and predictors of molecular typing in ccRCC. Differences in prognosis level, clinical stage and grade, immune infiltration, immunotherapy, and drug sensitivity between different subgroups indicate that this approach could provide valuable insights into senescence-related treatment options and prognostic assessment for patients with ccRCC. The function of the gene DUSP1 in ccRCC was validated through biological experiments, confirming its feasibility as a novel biomarker for ccRCC. These findings suggest that targeted therapies based on senescence-related mechanisms could be an effective treatment option for ccRCC.

The B56γ3-containing protein phosphatase 2A attenuates p70S6K-mediated negative feedback loop to enhance AKT-facilitated epithelial-mesenchymal transition in colorectal cancer

BACKGROUND

Protein phosphatase 2A (PP2A) is one of the major protein phosphatases in eukaryotic cells and is essential for cellular homeostasis. PP2A is a heterotrimer comprising the dimeric AC core enzyme and a highly variable regulatory B subunit. Distinct B subunits help the core enzyme gain full activity toward specific substrates and contribute to diverse cellular roles of PP2A. PP2A has been thought to play a tumor suppressor and the B56γ3 regulatory subunit was shown to play a key tumor suppressor regulatory subunit of PP2A. Nevertheless, we uncovered a molecular mechanism of how B56γ3 may act as an oncogene in colorectal cancer (CRC).

METHODS

Polyclonal pools of CRC cells with stable B56γ3 overexpression or knockdown were generated by retroviral or lentiviral infection and subsequent drug selection. Co-immunoprecipitation(co-IP) and in vitro pull-down analysis were applied to analyze the protein-protein interaction. Transwell migration and invasion assays were applied to investigate the role of B56γ3 in affecting motility and invasive capability of CRC cells. The sensitivity of CRC cells to 5-fluorouracil (5-FU) was analyzed using the PrestoBlue reagent assay for cell viability. Immunohistochemistry (IHC) was applied to investigate the expression levels of phospho-AKT and B56γ3 in paired tumor and normal tissue specimens of CRC. DataSets of TCGA and GEO were analyzed to investigate the correlation of B56γ3 expression with overall survival rates of CRC patients.

RESULTS

We showed that B56γ3 promoted epithelial-mesenchymal transition (EMT) and reduced the sensitivity of CRC cells to 5-FU through upregulating AKT activity. Mechanistically, B56γ3 upregulates AKT activity by targeting PP2A to attenuate the p70S6K-mediated negative feedback loop regulation on PI3K/AKT activation. B56γ3 was highly expressed and positively correlated with the level of phospho-AKT in tumor tissues of CRC. Moreover, high B56γ3 expression is associated with poor prognosis of a subset of patients with CRC.

CONCLUSIONS

Our finding reveals that the B56γ3 regulatory subunit-containing PP2A plays an oncogenic role in CRC cells by sustaining AKT activation through suppressing p70S6K activity and suggests that the interaction between B56γ3 and p70S6K may serve as a therapeutic target for CRC. Video Abstract.

Genkwanin suppresses mitochondrial dysfunction to alleviate IL-1β-elicited inflammation, apoptosis, and degradation of extracellular matrix in chondrocytes through upregulating DUSP1

Osteoarthritis (OA) is a form of chronic degenerative disease contributing to elevated disability rate among the elderly. Genkwanin is an active component extracted from Daphne genkwa possessing pharmacologic effects. Here, this study is designed to expound the specific role of genkwanin in OA and elaborate the probable downstream mechanism. First, the viability of chondrocytes in the presence or absence of interleukin-1 beta (IL-1β) treatment was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to assess cell apoptosis. Inflammatory response was estimated through enzyme-linked immunosorbent assay and Western blot. In addition, immunofluorescence staining and Western blot were utilized to measure the expression of extracellular matrix (ECM)-associated proteins. Dual-specificity protein phosphatase-1 (DUSP1) expression was tested by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot. Following DUSP1 elevation in genkwanin-treated chondrocytes exposed to IL-1β, inflammatory response and ECM-associated factors were evaluated as forementioned. In addition, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide staining was to assess the mitochondrial membrane potential. Adenosine triphosphate (ATP) level was examined with ATP assay kit, and RT-qPCR was used to test mitochondrial DNA expression. Results indicated that genkwanin administration enhanced the viability while ameliorated the apoptosis, inflammatory response, and ECM degradation in IL-1β-induced chondrocytes. Besides, genkwanin treatment fortified DUSP1 expression in IL-1β-exposed chondrocytes. DUSP1 interference further offsets the impacts of genkwanin on the inflammation, ECM degradation, and mitochondrial dysfunction in IL-1β-challenged chondrocytes. In short, genkwanin enhanced DUSP1 expression to mitigate mitochondrial dysfunction, thus ameliorating IL-1β-elicited inflammation, apoptosis, and degradation of ECM in chondrocytes.

DUSP4 promotes esophageal squamous cell carcinoma progression by dephosphorylating HSP90β

The molecular and pathogenic mechanisms of esophageal squamous cell carcinoma (ESCC) development are still unclear, which hinders the development of effective treatments. In this study, we report that DUSP4 is highly expressed in human ESCC and is negatively correlated with patient prognosis. Knockdown of DUSP4 suppresses cell proliferation and patient-derived xenograft (PDX)-derived organoid (PDXO) growth and inhibits cell-derived xenograft (CDX) development. Mechanistically, DUSP4 directly binds to heat shock protein isoform β (HSP90β) and promotes the ATPase activity of HSP90β by dephosphorylating HSP90β on T214 and Y216. These dephosphorylation sites are critical for the stability of JAK1/2-STAT3 signaling and p-STAT3 (Y705) nucleus translocation. In vivo, Dusp4 knockout in mice significantly inhibits 4-nitrochinoline-oxide-induced esophageal tumorigenesis. Moreover, DUSP4 lentivirus or treatment with HSP90β inhibitor (NVP-BEP800) significantly impedes PDX tumor growth and inactivates the JAK1/2-STAT3 signaling pathway. These data provide insight into the role of the DUSP4-HSP90β-JAK1/2-STAT3 axis in ESCC progression and describe a strategy for ESCC treatment.

A DUSP6 inhibitor suppresses inflammatory cardiac remodeling and improves heart function after myocardial infarction

Acute myocardial infarction (MI) results in loss of cardiomyocytes and abnormal cardiac remodeling with severe inflammation and fibrosis. However, how cardiac repair can be achieved by timely resolution of inflammation and cardiac fibrosis remains incompletely understood. Our previous findings have shown that dual-specificity phosphatase 6 (DUSP6) is a regeneration repressor from zebrafish to rats. In this study, we found that intravenous administration of the DUSP6 inhibitor (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI) improved heart function and reduced cardiac fibrosis in MI rats. Mechanistic analysis revealed that BCI attenuated macrophage inflammation through NF-κB and p38 signaling, independent of DUSP6 inhibition, leading to the downregulation of various cytokines and chemokines. In addition, BCI suppressed differentiation-related signaling pathways and decreased bone-marrow cell differentiation into macrophages through inhibiting DUSP6. Furthermore, intramyocardial injection of poly (D, L-lactic-co-glycolic acid)-loaded BCI after MI had a notable effect on cardiac repair. In summary, BCI improves heart function and reduces abnormal cardiac remodeling by inhibiting macrophage formation and inflammation post-MI, thus providing a promising pro-drug candidate for the treatment of MI and related heart diseases. This article has an associated First Person interview with the first author of the paper.

Identification of MAP Kinase Kinase 3 as a protein target of myricetin in non-small cell lung cancer cells

Myricetin is a typical flavonol with various pharmacological effects which shows favorable biological activities in cancer. However, the underlying mechanisms and potential targets of myricetin in NSCLC (non-small cell lung cancer) cells remain unclear. First, we demonstrated that myricetin not only inhibited the proliferation, migration and invasion, but also induced apoptosis in A549 and H1299 cells in a dose-dependent manner. Then, we confirmed myricetin may play an anti-NSCLC effect through modulating MAPK-related functions and signaling pathway by Network pharmacology. Furthermore, MKK3 (MAP Kinase Kinase 3) was identified and confirmed as a potential target of myricetin by biolayer interferometry (BLI) and molecular docking, revealing that myricetin directly bound to MKK3. Moreover, three mutations (D208, L240, and Y245) of key amino acids predicted by molecular docking obviously decreased the affinity between myricetin and MKK3. Finally, enzyme activity assay was utilized to determine the effect of myricetin on MKK3 activity in vitro, and the result showed that myricetin attenuated MKK3 activity. Subsequently, myricetin decreased the phosphorylation of p38 MAPK. Furthermore, knockdown of MKK3 reduced the susceptibility of A549 and H1299 cells to myricetin. These results suggested that myricetin inhibited the growth of NSCLC cells via targeting MKK3 and influencing the downstream p38 MAPK signaling pathway. The findings revealed that MKK3 is a potential target of myricetin in the NSCLC and myricetin is considered to be a small-molecular inhibitor of MKK3, which can improve comprehension of the molecular mechanisms of myricetin pharmacological effects in cancer and further development of MKK3 inhibitors.

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.

DUSP4 inhibits autophagic cell death and apoptosis in colorectal cancer by regulating BCL2-Beclin1/Bax signaling

BACKGROUND

The DUSP4 gene plays an important role in the carcinogenesis of colorectal cancer (CRC). However, the underlying mechanism of DUSP4-regulated colorectal carcinogenesis is unknown. DUSP4 is a negative regulator of the MAP kinase (MAPK) JNK, and JNK-mediated BCL2 phosphorylation is associated with apoptosis and autophagic cell death. Our study aimed to explore the significance of BCL2 phosphorylation-dependent autophagy and apoptosis in DUSP4-promoted colorectal carcinogenesis.

METHODS

We first investigated the roles of DUSP4 in the survival of HCT116 and SW480 CRC cell lines using gene-silencing and -overexpression techniques. Next, we explored the effects of DUSP4 on the BCL2 phosphorylation, autophagy and apoptosis of HCT116 and SW480 cells. Ultimately, with the help of pharmacological inhibitors of Beclin1 and BCL2 (spautin-1 and ABT-737), the relationship between BCL2-Beclin1/Bax signaling and DUSP4-regulated autophagy, apoptosis, survival and migration in HCT116 cells was clarified.

RESULTS

Our results first confirmed the contribution of DUSP4 to the survival of HCT116 and SW480 cells. In addition, DUSP4 silencing resulted in BCL2 phosphorylation and the enhancement in autophagy and apoptosis in HCT116 and SW480 cells, while DUSP4 overexpression showed the opposite effect. Moreover, DUSP4 silencing inhibited the protein interaction between BCL2 and Beclin1 or Bax in HCT116 cells. Moreover, the survival and migration of HCT116 cells inhibited by DUSP4 silencing were blocked by autophagy inhibition with spautin-1. Notably, the survival and migration of HCT116 cells promoted by DUSP4 overexpression were reversed by ABT-737.

CONCLUSIONS

It was indicated that DUSP4 can maintain the survival and function of CRC cells by inhibiting BCL2 phosphorylation-dependent autophagic cell death and apoptosis.

Mitogen-Activated Protein Kinase Phosphatases: No Longer Undruggable?

Phosphatases and kinases maintain an equilibrium of dephosphorylated and phosphorylated proteins, respectively, that are required for critical cellular functions. Imbalance in this equilibrium or irregularity in their function causes unfavorable cellular effects that have been implicated in the development of numerous diseases. Protein tyrosine phosphatases (PTPs) catalyze the dephosphorylation of protein substrates on tyrosine residues, and their involvement in cell signaling and diseases such as cancer and inflammatory and metabolic diseases has made them attractive therapeutic targets. However, PTPs have proved challenging in therapeutics development, garnering them the unfavorable reputation of being undruggable. Nonetheless, great strides have been made toward the inhibition of PTPs over the past decade. Here, we discuss the advancement in small-molecule inhibition for the PTP subfamily known as the mitogen-activated protein kinase (MAPK) phosphatases (MKPs). We review strategies and inhibitor discovery tools that have proven successful for small-molecule inhibition of the MKPs and discuss what the future of MKP inhibition potentially might yield.

Investigating the Role of DUSP4 in Uveal Melanoma

Purpose

Dual-specificity phosphatase 4 (DUSP4) inactivates factors in the mitogen-activated protein kinase (MAPK) signaling cascade, activated in uveal melanoma (UM) by mutations in upstream G-protein α subunits GNAQ/11 in >90% cases. This study examined whether DUSP4 (1) protein expression in primary UM (pUM) was a biomarker of metastatic risk and (2) knockdown sensitized UM cells to therapeutic agents, selumetinib or doxorubicin.

Methods

DUSP4 mRNA data from The Cancer Genome Atlas and DUSP4 protein expression examined using immunohistochemistry in 28 cases of pUM were evaluated for association with clinical, genetic, and histological features. In vitro cytotoxic drug assays tested the efficacy of selumetinib and doxorubicin in UM cell lines with/without small interfering RNA DUSP4 gene silencing.

Results

DUSP4 protein expression was observed in 93% of cases, with strong nuclear positivity in 79%. Despite higher DUSP4 messenger RNA levels in disomy 3/wild-type BAP1 UM, there was no significant association of nDUSP4 protein with these metastatic risk predictors or outcome. DUSP4 expression in UM cell lines varied. DUSP4 silencing in Mel202, MP46, and MP41 cells did not affect ERK1/2 or phospho-ERK levels. Despite increased phospho-ERK levels in Mel285, no cell line showed enhanced sensitivity to selumetinib/doxorubicin.

Conclusions

DUSP4 protein expression is not a biomarker of UM metastatic risk. DUSP4 plays a complex role in oncogenesis, as reported in other cancers, and further work is required to fully understand its functional role in the MAPK pathway.

Translational Relevance

Understanding the role of phosphatases, such as DUSP4, in the control of intracellular signaling cascades will facilitate our ability to identify successful treatment options.

Functional cooperation between IKCa and TRPC1 channels regulates serum-induced vascular smooth muscle cell proliferation via mediating Ca2+ influx and ERK1/2 activation

The increased proliferation of vascular smooth muscle cells (VSMCs) contributes to the pathogenesis of vascular diseases. The intermediate conductance calcium-activated potassium (IK_Ca ) channel plays a critical role in VSMC proliferation by raising the intracellular calcium concentration ([Ca²⁺ ]_i ), but the underlying mechanism is still not unclear. Here we investigated the cooperation between IK_Ca and transient receptor potential canonical 1 (TRPC1) channels in mediating extracellular Ca²⁺ entry, which in turn activates downstream Ca²⁺ signalling in the regulation of VSMC proliferation using serum-induced cell proliferation model. Serum-induced cell proliferation was accompanied with up-regulation of IK_Ca expression and an increase in [Ca²⁺ ]_i . Serum-induced cell proliferation and increase in [Ca²⁺ ]_i were suppressed by IK_Ca inhibition with TRAM-34 or IK_Ca knockdown. Serum-induced cell proliferation was strongly reduced by the removal of extracellular Ca²⁺ with EGTA or intracellular Ca²⁺ with BAPTA-AM and, additionally, by TRPC1 knockdown. Moreover, the increase in [Ca²⁺ ]_i induced by serum or by IK_Ca activation with 1-EBIO was attenuated by TRPC1 knockdown. Finally, serum induced ERK1/2 activation, which was attenuated by treatment with TRAM-34 or BAPTA-AM, as well as TRPC1 knockdown. Consistently, serum-induced cell proliferation was suppressed by ERK1/2 inhibition with PD98059. Taken together, these results suggest that the IK_Ca and TRPC1 channels cooperate in mediating Ca²⁺ influx that activates the ERK1/2 pathway to promote cell proliferation, thus providing new mechanistic insights into VSMC proliferation.

BCI, an inhibitor of the DUSP1 and DUSP6 dual specificity phosphatases, enhances P2X7 receptor expression in neuroblastoma cells

P2X7 receptor (P2RX7) is expressed strongly by most human cancers, including neuroblastoma, where high levels of P2RX7 are correlated with a poor prognosis for patients. Tonic activation of P2X7 receptor favors cell metabolism and angiogenesis, thereby promoting cancer cell proliferation, immunosuppression, and metastasis. Although understanding the mechanisms that control P2X7 receptor levels in neuroblastoma cells could be biologically and clinically relevant, the intracellular signaling pathways involved in this regulation remain poorly understood. Here we show that (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one (BCI), an allosteric inhibitor of dual specificity phosphatases (DUSP) 1 and 6, enhances the expression of P2X7 receptor in N2a neuroblastoma cells. We found that exposure to BCI induces the phosphorylation of mitogen-activated protein kinases p38 and JNK, while it prevents the phosphorylation of ERK1/2. BCI enhanced dual specificity phosphatase 1 expression, whereas it induced a decrease in the dual specificity phosphatase 6 transcripts, suggesting that BCI-dependent inhibition of dual specificity phosphatase 1 may be responsible for the increase in p38 and JNK phosphorylation. The weaker ERK phosphorylation induced by BCI was reversed by p38 inhibition, indicating that this MAPK is involved in the regulatory loop that dampens ERK activity. The PP2A phosphatase appears to be implicated in the p38-dependent dephosphorylation of ERK1/2. In addition, the PTEN phosphatase inhibition also prevented ERK1/2 dephosphorylation, probably through p38 downregulation. By contrast, inhibition of the p53 nuclear factor decreased ERK phosphorylation, probably enhancing the activity of p38. Finally, the inhibition of either p38 or Sp1-dependent transcription halved the increase in P2X7 receptor expression induced by BCI. Moreover, the combined inhibition of both p38 and Sp1 completely prevented the effect exerted by BCI. Together, our results indicate that dual specificity phosphatase 1 acts as a novel negative regulator of P2X7 receptor expression in neuroblastoma cells due to the downregulation of the p38 pathway.

cyy-287, a novel pyrimidine-2,4-diamine derivative, inhibits tumor growth of EGFR-driven non-small cell lung cancer via the ERK pathway

In recent decades, EGFR-targeted tyrosine kinase inhibitors (TKIs) have been proven to be an effective therapy for EGFR-mutant non-small cell lung cancer (NSCLC). However, resistance to EGFR-TKIs limits their clinical application. In the present study, we investigate the antitumor effect and underlying mechanism of a novel pyrimidine-2,4-diamine derivative, cyy-287, in NSCLC. We find that cyy-287 has a high affinity for lung tissue and inhibits the proliferation of NSCLC cells. Interestingly, the significant suppression of migration and induction of apoptosis by cyy-287 are only observed in EGFR-driven but not in EGFR-wild-type (wt) cells. According to the RNA sequencing and KEGG enrichment analysis results, cyy-287 markedly inhibits the MAPK pathway in EGFR-driven PC9 cells, and western blot analysis results further indicate that cyy-287 selectively blocks the ERK pathway in EGFR-driven cells. Meanwhile, apoptosis induced by cyy-287 could be partially reversed by ERK pathway inhibition. Further experiment indicates that cyy-287 inhibits the EGFR pathway in both EGFR-driven and EGFR-overexpressing cells. Interestingly, it only induces apoptosis in EGFR-driven cells, not in EGFR-overexpressing cells. The growth of EGFR-driven cells is suppressed by cyy-287 in vivo, with fewer side effects. Our results suggest that cyy-287 may be a potential therapeutic drug with promising antitumor effects against NSCLC.

Amphiphilic Aminated Derivatives of [60]Fullerene as Potent Inhibitors of Tumor Growth and Metastasis

Malignant proliferation and metastasis are the hallmarks of cancer cells. Aminated [70]fullerene exhibits notable antineoplastic effects, promoting it a candidate for multi-targeted cancer drugs. It is an urgent need to reveal the structure-activity relationship for antineoplastic aminated fullerenes. Herein, three amphiphilic derivatives of [60]fullerene with clarified molecular structures are synthesized: TAPC-4, TAPC-3, and TCPC-4. TAPC-4 inhibits the proliferation of diverse tumor cells via G0/G1 cell cycle arrest, reverses the epithelial-mesenchymal transition, and abrogates the high mobility of tumor cells. TAPC-4 can be excreted from the organism and achieves an in vivo inhibition index of 75.5% in tumor proliferation and 87.5% in metastatic melanoma with a wide safety margin. Molecular dynamics simulations reveal that the amphiphilic molecular structure and the ending amino groups promote the targeting of TAPC-4 to heat shock protein Hsp90-beta, vimentin, and myosin heavy chain 9 (MYH9), probably resulting in the alteration of cyclin D1 translation, vimentin expression, and MYH9 location, respectively. This work initially emphasizes the dominant role of the amphiphilic structure and the terminal amino moieties in the antineoplastic effects of aminated fullerenes, providing fundamental support for their anti-tumor drug development.

Quantitative Proteomics Based on iTRAQ Reveal that Nitidine Chloride Induces Apoptosis by Activating JNK/c-Jun Signaling in Hepatocellular Carcinoma Cells

The aim of the present study was to investigate the cytotoxic effects and underlying molecular mechanisms of nitidine chloride (NC) in hepatocellular carcinoma cells via quantitative proteomics. MTT assays were used to detect the inhibitory effects of NC in Bel-7402 liver cancer cells, and the number of apoptotic cells was measured by flow cytometry. Quantitative proteomics technology based on iTRAQ was used to discover differential expressed proteins after NC treatment, and bioinformatic techniques were further used to screen potential targets of NC. Molecular docking was applied to evaluate the docking activity of NC with possible upstream proteins, and their expression was detected at the mRNA and protein levels by quantitative reverse transcription PCR and western blotting. NC inhibited the proliferation of Bel-7402 cells after 24 h of treatment and stimulated apoptosis in vitro. The proteomics experiment showed that NC triggers mitochondrial damage in HCC cells and transcription factor AP-1 (c-Jun) may be a potential target of NC (fold change = 4.36 ± 0.23). Molecular docking results revealed the highest docking score of NC with c-Jun N-terminal kinase (JNK), one of the upstream proteins of c-Jun. Moreover, the mRNA and protein expression of c-Jun and JNK were significantly increased after NC treatment (p < 0.05). These findings indicate that NC significantly induced mitochondrial damage in HCC cells, and induced apoptosis by activating JNK/c-Jun signaling.

The role of cyclins in the development and progression of prostate cancer

The role of cyclins in hormone-dependent neoplasms is crucial in the development of the disease that is resistant to first-line therapy, as the example of breast cancer shows. However, in prostate cancer, cyclins are studied to a lesser extent. There are some well-described molecular pathways, including cyclins A1 and D1 signaling, however the role of other cyclins, e.g., D2, D3, E, and H, still requires further investigation. Recent studies indicate that cyclins regulate various cellular processes, not only the cell cycle. Furthermore, they remain in cross-talk with many other signaling pathways, e.g., MAPK/ERK, PI3K/Akt, and Notch. The androgen signaling axis, which is pivotal in prostate cancer progression, interferes with cyclin pathways at many levels. This article summarizes current knowledge on the influence of cyclins on prostate cancer progression by describing interactions between the androgen receptor and cyclins, as well as mechanisms underlying the development of resistance to currently used therapies.

U0126: Not only a MAPK kinase inhibitor

U0126, as an inhibitor of the MAPK signaling pathway, is closely related to various biological processes, such as differentiation, cell growth, autophagy, apoptosis, and stress responses. It makes U0126 play an essential role in balancing cellular homeostasis. Although U0126 has been suggested to inhibit various cancers, its complete mechanisms have not been clarified in cancers. This review summarized the most recent and relevant research on the many applications of U0126 and described its role and mechanisms in different cancer cell types. Moreover, some acknowledged functions of U0126 researched in the laboratory were listed in our review. We discussed the probability of using U0126 to restain cancers or suppress the MAPK pathway as a novel way of cancer treatment.

The cytotoxic action of BCI is not dependent on its stated DUSP1 or DUSP6 targets in neuroblastoma cells

Neuroblastoma (NB) is a heterogeneous cancer of the sympathetic nervous system, which accounts for 7-10% of paediatric malignancies worldwide. Due to the lack of targetable molecular aberrations in NB, most treatment options remain relatively nonspecific. Here, we investigated the therapeutic potential of BCI, an inhibitor of DUSP1 and DUSP6, in cultured NB cells. BCI was cytotoxic in a range of NB cell lines and induced a short-lived activation of the AKT and stress-inducible MAP kinases, although ERK phosphorylation was unaffected. Furthermore, a phosphoproteomic screen identified significant upregulation of JNK signalling components and suppression in mTOR and R6K signalling. To assess the specificity of BCI, CRISPR-Cas9 was employed to introduce insertions and deletions in the DUSP1 and DUSP6 genes. Surprisingly, BCI remained fully cytotoxic in NB cells with complete loss of DUSP6 and partial depletion of DUSP1, suggesting that BCI exerts cytotoxicity in NB cells through a complex mechanism that is unrelated to these phosphatases. Overall, these data highlight the risk of using an inhibitor such as BCI as supposedly specific DUSP1/6, without understanding its full range of targets in cancer cells.

Integrating Network Pharmacology and Experimental Verification to Explore the Pharmacological Mechanisms of Aloin Against Gastric Cancer

Purpose

This study was designed to evaluate the pharmacological mechanisms of Aloin against gastric cancer (GC) via network pharmacology analysis combined with experimental verification.

Methods

Using network pharmacology methods, the potential targets of Aloin and targets related to GC were screened from public databases. The protein–protein interaction (PPI) network, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed to predict the core targets and pathways of Aloin against GC. The expressions of major targets predicted by network pharmacology in normal stomach tissues and GC tissues and their relationships with overall survival of GC were searched in GEPIA, HPA and DriverDBv3 database. The results of network pharmacology analysis were verified by in vitro experiments.

Results

A total of 129 potential targets were retrieved by searching the intersection of Aloin and GC targets. PPI network analysis indicated that 10 targets, including AKT1 and CASP3, were hub genes. GO enrichment analysis involved 93 biological processes, 19 cellular components, and 37 molecular functions. KEGG enrichment analysis indicated that the anti-cancer effect of Aloin was mediated through multiple pathways, such as PI3K-AKT, FoxO and Ras signaling pathway. Among them, the PI3K-AKT signaling pathway, which contained the largest number of enriched genes, may play a greater role in the treatment of GC. The validation of key targets in GEPIA, HPA and DriverDBv3 database showed that the verification results for most core genes were consistent with this study. Then, the results of in vitro experiment indicated that Aloin could inhibit proliferation of NCI-N87 cells and induce cell apoptosis. The results also showed that Aloin could decrease the mRNA and protein expressions of PI3K and AKT, suggesting that Aloin can treat GC by inducing cell apoptosis and regulating the PI3K-AKT signaling pathway.

Conclusion

This study identified the potential targets of Aloin against GC using network pharmacology and in vitro verification, which provided a new understanding of the pharmacological mechanisms of Aloin in treatment of GC.

A Bibliometric Analysis of Triptolide and the Recent Advances in Treating Non–Small Cell Lung Cancer

In recent decades, natural products derived from plants and their derivatives have attracted great interest in the field of disease treatment. Triptolide is a tricyclic diterpene extracted from Tripterygium wilfordii, a traditional Chinese medicine, which has shown excellent therapeutic potential in the fields of immune inflammation and cancer treatment. In this study, 1,106 Web-of-Science-indexed manuscripts and 1,160 Chinese-National-Knowledge-Infrastructure-indexed manuscripts regarding triptolide published between 2011 and 2021 were analyzed, mapping the co-occurrence networks of keywords and clusters using CiteSpace software. The research frontier and development trend were determined by keyword frequency and cluster analysis, which can be used to predict the future research development of triptolide. Non–small cell lung cancer (NSCLC) is most common in lung cancer patients, accounting for about 80% of all lung cancer patients. New evidence suggests that triptolide effectively inhibits the development and metastasis of NSCLC by the induction of apoptosis, reversion of EMT, and regulation of gene expression. Specifically, it acts on NF-κB, MAPKs, P53, Wnt/β-catenin, and microRNAs (miRNAs), signaling pathways and molecular mechanisms. Consequently, this article reviews the research progress of the anti-NSCLC effect of triptolide. In addition, attenuated studies on triptolide and the potential of tumor immunotherapy are also discussed.

Dual-specificity phosphatase 8 (DUSP8) induces drug resistance in breast cancer by regulating MAPK pathways

The aim of the study was to explore the role and molecular mechanism of dual-specificity phosphatase 8 (DUSP8) in the drug resistance of trastuzumab in breast cancer. Real-time PCR and western blot detected the difference in expression of DUSP8 between breast cancer tissue/cells and trastuzumab-resistant tissues/cells. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of DUSP8 in breast cancer. si-DUSP8 or dusp8 overexpression vector was transiently transfected, and the effects of si-DUSP8 on apoptosis, cell viability and cell migration of drug-resistant cell lines were investigated by flow cytometry, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) and Transwell assays, and its regulation mechanism finally explored. The results showed that the expression of DUSP8 in breast cancer tissues and cells was significantly higher than in matched non-tumor tissues and cells. DUSP8 was significantly upregulated in non-responsive patients compared with patients who responded to trastuzumab. ROC analysis showed that the area under the curve was 0.732, and the diagnostic sensitivity and specificity were 64.86% and 75.76%. DUSP8 knockdown promotes apoptosis and reduces trastuzumab resistance in BT474/TR and SKBR3/TR cells by inhibiting cell migration and cell viability. Knockdown of DUSP8 increased the expression of p-p38 and p-ERK, and the regulation of DUSP8 in chemotherapy resistance of breast cancer cells may be realized by mediating mitogen-activated protein kinase (MAPK)-related signaling pathways. In conclusion, knockdown of DUSP8 expression in trastuzumab-resistant cells can inhibit cell migration and proliferation, and leads to decreased drug resistance by activating MAPK signaling pathway in trastuzumab-resistant cells.

Molecular Mechanism Based on Histopathology, Antioxidant System and Transcriptomic Profiles in Heat Stress Response in the Gills of Japanese Flounder

As an economically important flatfish in Asia, Japanese flounder is threatened by continuously rising temperatures due to global warming. To understand the molecular responses of this species to temperature stress, adult Japanese flounder individuals were treated with two kinds of heat stress—a gradual temperature rise (GTR) and an abrupt temperature rise (ATR)—in aquaria under experimental conditions. Changes in histopathology, programmed cell death levels and the oxidative stress status of gills were investigated. Histopathology showed that the damage caused by ATR stress was more serious. TUNEL signals confirmed this result, showing more programmed cell death in the ATR group. In addition, reactive oxygen species (ROS) levels and the 8-O-hDG contents of both the GTR and ATR groups increased significantly, and the total superoxide dismutase (T-SOD) activities and total antioxidant capacity (T-AOC) levels decreased in the two stressed groups, which showed damage to antioxidant systems. Meanwhile, RNA-seq was utilized to illustrate the molecular mechanisms underyling gill damage. Compared to the control group of 18 °C, 507 differentially expressed genes (DEGs) were screened in the GTR group; 341 were up-regulated and 166 were down-regulated, and pathway enrichment analysis indicated that they were involved in regulation and adaptation, including chaperone and folding catalyst pathways, the mitogen-activated protein kinase signaling (MAPK) pathway and DNA replication protein pathways. After ATR stress, 1070 DEGs were identified, 627 were up-regulated and 423 were down-regulated, and most DEGs were involved in chaperone and folding catalyst and DNA-related pathways, such as DNA replication proteins and nucleotide excision repair. The annotation of DEGs showed the great importance of heat shock proteins (HSPs) in protecting Japanese flounder from heat stress injury; 12 hsp genes were found after GTR, while 5 hsp genes were found after ATR. In summary, our study records gill dysfunction after heat stress, with different response patterns observed in the two experimental designs; chaperones were activated to defend heat stress after GTR, while replication was almost abandoned due to the severe damage consequent on ATR stress.

Comparative Transcriptome Analysis of Spleen Reveals Potential Regulation of Genes and Immune Pathways Following Administration of Aeromonas salmonicida subsp. masoucida Vaccine in Atlantic Salmon (Salmo salar)

Aeromonas salmonicida is a global fish pathogen. Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and caused huge losses to salmonid industry in China. Hence, it is of great significance to develop ASM vaccine and explore its protection mechanism in salmonids. In this regard, we conducted RNA-seq analysis with spleen tissue of Atlantic salmon after ASM vaccination to reveal genes, their expression patterns, and pathways involved in immune protections. In our results, a total of 441.63 million clean reads were obtained, and 389.37 million reads were mapped onto the Atlantic salmon reference genome. In addition, 1125, 2126, 1098, 820, and 1351 genes were significantly up-regulated, and 747, 2626, 818, 254, and 908 genes were significantly down-regulated post-ASM vaccination at 12 h, 24 h, 1 month, 2 months, and 3 months, respectively. Subsequent pathway analysis revealed that many differentially expressed genes (DEGs) following ASM vaccination were involved in cytokine-cytokine receptor interaction (TNFRSF11b, IL-17RA, CCR9, and CXCL11), HTLV-I infection (MR1 and HTLV-1), MAPK signaling pathway (MAPK, IL8, and TNF-α-1), PI3K-Akt signaling pathway (PIK3R3, THBS4, and COL2A1), and TNF signaling pathway (PTGS2, TNFRSF21-l, and CXCL10). Finally, the results of qRT-PCR showed a significant correlation with RNA-seq results, suggesting the reliability of RNA-seq for gene expression analysis. This study provided insights into regulation of gene expression and their involved pathways in Atlantic salmon spleen in responses to vaccine, and set the foundation for further study on the vaccine protective mechanism in Atlantic salmon as well as other teleost species.

Melamine induced changes in histopathology of the main organs and transcriptional levels of MAPK signaling genes in kidneys of female mice

Melamine is an important chemical raw material used in industries, which has potential health risks to animals and humans. Current research mainly focuses on the toxic effects of high-dose melamine ingestion. However, there are few reports on whether melamine at the current limited standard dose has adverse effects on various tissues and organs, and whether there are sensitive target genes for risk evaluation. For this, 24 female Kunming mice were fed 0, 1.8-, 3.6-, and 7.2- mg/kg/d melamine via drinking water for consecutive 28 days, respectively. The morphological changes of the ovarian, hepatic, and renal tissues were firstly observed. The results demonstrated that the histopathology of ovary, liver, and especially in kidney had been altered by melamine intake in female. And then, the transcriptional levels of MAPK signaling genes including p38, ERK1, ERK2, JNK1, and JNK2 in kidneys were investigated by real-time PCR. The data showed that ERK1 and p38 mRNAs expressions were up-regulated significantly by melamine, suggesting that ERK1 and p38 transcriptional levels in the kidney might to be considered as candidate targets for lower-dose melamine toxicity. This study not only provides potential targets for the diagnosis and prevention of melamine damage, but also helps to assess the health risks of the current minimum allowable levels of melamine in food and environment.

The SKA3-DUSP2 Axis Promotes Gastric Cancer Tumorigenesis and Epithelial-Mesenchymal Transition by Activating the MAPK/ERK Pathway

Background: Spindle and kinetochore-related complex subunit 3 (SKA3), a member of the SKA family of proteins, is associated with the progression of multiple cancers. However, the role of SKA3 in gastric cancer has not been studied.

Methods: The expression levels of SKA3 and dual-specificity phosphatase 2 (DUSP2) proteins were detected by immunohistochemistry. The effects of SKA3 and DUSP2 on the proliferation, migration, invasion, adhesion, and epithelial-mesenchymal transition of gastric cancer were studied in vitro and in vivo.

Results: Immunohistochemical analysis of 164 cases of gastric cancer revealed that high expression of SKA3 was negatively correlated with DUSP2 expression and related to N stage, peritoneal metastasis, and poor prognosis. In vitro studies showed that silencing SKA3 expression inhibited the proliferation, migration, invasion, adhesion and epithelial-mesenchymal transition of gastric cancer. In vivo experiments showed that silencing SKA3 inhibited tumor growth and peritoneal metastasis. Mechanistically, SKA3 negative regulates the tumor suppressor DUSP2 and activates the MAPK/ERK pathway to promote gastric cancer.

Conclusion: Our results indicate that the SKA3-DUSP2-ERK1/2 axis is involved in the regulation of gastric cancer progression, and SKA3 is a potential therapeutic target for gastric cancer.

Dual-specificity phosphatases: therapeutic targets in cancer therapy resistance

PURPOSE

Therapy resistance is the principal obstacle to achieving cures in cancer patients and its successful tackling requires a deep understanding of the resistance mediators. Increasing evidence indicates that tumor phosphatases are novel and druggable targets in translational oncology and their modulation may hinder tumor growth and motility and potentiate therapeutic sensitivity in various neoplasms via regulation of various signal transduction pathways. Dual-specificity phosphatases (DUSPs) are key players of cell growth, survival and death and have essential roles in tumor initiation, malignant progression and therapy resistance through regulation of the MAPK signaling pathway. In this review, different aspects of DUSPs are discussed.

METHODS

A comprehensive literature review was performed using various websites including PubMed.

RESULTS

We provide mechanistic insights into the roles of well-known DUSPs in resistance to a wide range of cancer therapeutic approaches including chemotherapy, radiation and molecular targeted therapy in human malignancies. Moreover, we discuss the development of DUSP modulators, with a focus on DUSP1 and 6 inhibitors. Ultimately, the preclinical investigations of small molecule inhibitors of DUSP1 and 6 are outlined.

CONCLUSION

Emerging evidence indicates that the DUSP family is aberrantly expressed in human malignancies and plays critical roles in determining sensitivity to a wide range of cancer therapeutic strategies through regulation of the MAPK signaling pathways. Consequently, targeting DUSPs and their downstream molecules can pave the way for more effective cancer therapies.

Alantolactone: A Natural Plant Extract as a Potential Therapeutic Agent for Cancer

Alantolactone (ALT) is a natural compound extracted from Chinese traditional medicine Inula helenium L. with therapeutic potential in the treatment of various diseases. Recently, in vitro and in vivo studies have indicated cytotoxic effects of ALT on various cancers, including liver cancer, colorectal cancer, breast cancer, etc. The inhibitory effects of ALT depend on several cancer-associated signaling pathways and abnormal regulatory factors in cancer cells. Moreover, emerging studies have reported several promising strategies to enhance the oral bioavailability of ALT, such as combining ALT with other herbs and using ALT-entrapped nanostructured carriers. In this review, studies on the anti-tumor roles of ALT are mainly summarized, and the underlying molecular mechanisms of ALT exerting anticancer effects on cells investigated in animal-based studies are also discussed.

Identification, evolution and expression analyses of mapk gene family in Japanese flounder (Paralichthys olivaceus) provide insight into its divergent functions on biotic and abiotic stresses response

Mitogen-activated protein kinase (MAPK) are a series of serine/threonine protein kinases showing evolutionary conservation, which can be activated by many stimulus signals and then transfer them from cell membrane to nucleus. MAPKs regulate a variety of biological processes, such as apoptosis, hormone signaling and immune response. In this study, 14 putative mapk genes in Japanese flounder were identified, and their basic physical and chemical properties were characterized. Phylogenetic analysis showed that mapk genes were divided into three main subfamilies, including ERK, JNK and the p38 MAPK. Selection pressure analysis revealed they were evolutionarily-constrained and undergone strong purifying selection. Gene structure and conserved protein motif comparison suggested high levels of conservation in members of mapk gene family. The expression patterns were further investigated in each embryonic and larval development stages and different tissues. In addition, RNA-seq analyses after bacteria and temperature stresses suggested mapk genes had different expression patterns. Three mapk genes showed significant differences in response to E. tarda challenge and five were induced significantly after temperature stress, indicating their potential functions. This systematic analysis provided valuable information for further understanding of the regulation mechanism of mapk gene family under different stresses in Japanese flounder.

Molecular Activation of the Kv11.1 Channel Reprograms EMT in Colon Cancer by Inhibiting TGFβ Signaling via Activation of Calcineurin

Control of ionic gradients is critical to maintain cellular homeostasis in both physiological and pathological conditions, but the role of ion channels in cancer cells has not been studied thoroughly. In this work we demonstrated that activity of the Kv11.1 potassium channel plays a vital role in controlling the migration of colon cancer cells by reversing the epithelial-to-mesenchymal transition (EMT) into the mesenchymal-to-epithelial transition (MET). We discovered that pharmacological stimulation of the Kv11.1 channel with the activator molecule NS1643 produces a strong inhibition of colon cancer cell motility. In agreement with the reversal of EMT, NS1643 treatment leads to a depletion of mesenchymal markers such as SNAIL1, SLUG, TWIST, ZEB, N-cadherin, and c-Myc, while the epithelial marker E-cadherin was strongly upregulated. Investigating the mechanism linking Kv11.1 activity to reversal of EMT into MET revealed that stimulation of Kv11.1 produced a strong and fast inhibition of the TGFβ signaling. Application of NS1643 resulted in de-phosphorylation of the TGFβ downstream effectors R-SMADs by activation of the serine/threonine phosphatase PP2B (calcineurin). Consistent with the role of TGFβ in controlling cancer stemness, NS1643 also produced a strong inhibition of NANOG, SOX2, and OCT4 while arresting the cell cycle in G0/G1. Our data demonstrate that activation of the Kv11.1 channel reprograms EMT into MET by inhibiting TGFβ signaling, which results in inhibition of motility in colon cancer cells.

AKIP1 promotes tumor progression by cancer-related pathways and predicts prognosis in tongue squamous cell carcinoma

The current study was designed to explore the effect of A-kinase-interacting protein 1 (AKIP1) on tongue squamous cell carcinoma (TSCC) viability and mobility and to investigate its molecular mechanism. Control overexpression (OE-NC group) and AKIP1 overexpression (OE-AKIP1 group) plasmids were transfected into CAL-27 cells; control knockdown (KD-NC group) and AKIP1 knockdown (KD-AKIP1 group) plasmids were transfected into SCC-9 cells. Cellular viability and mobility were determined, and mRNA sequencing was performed followed by RT-qPCR validation. Immunohistochemistry was utilized to detect AKIP1 expression in tumor and adjacent tissues from 90 TSCC patients. AKIP1 was more highly expressed in human TSCC cell lines compared to human normal lingual epithelial cells. Cell proliferation, migration, and invasion were increased in the OE-AKIP1 group compared to the OE-NC group but decreased in the KD-AKIP1 group compared to the KD-NC group. mRNA sequencing revealed 436 differentially expressed genes; most of the genes were mainly enriched in the mTOR, PI3K-Akt, MAPK, Hippo, and Wnt signaling pathways. These findings were subsequently confirmed by RT-qPCR quantification. In TSCC patients, AKIP1 expression was increased in tumor tissues and related to increased tumor size, lymph node metastasis and poor overall survival. AKIP1 is a therapeutic target that regulates multiple tumor-related pathways in TSCC.

CDKN2B antisense RNA 1 suppresses tumor growth in human colorectal cancer by targeting MAPK inactivator dual-specificity phosphatase 1

Aberrant expression of long noncoding RNA cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) has been detected in human colorectal cancer (CRC). This study aimed to investigate the role of CDKN2B-AS1 and the underlying mechanism in human CRC. Gain- and loss-of-function assays were performed to explore the role of CDKN2B-AS1 in the malignant behavior of HCT116 and SW480 CRC cells in vitro and in vivo. RNA pull-down assay was conducted to identify the target of CDKN2B-AS1 in CRC cells. The physical and functional interactions between CDKN2B-AS1 and the target were examined. CDKN2B-AS1 inhibited CRC cell proliferation and migration while promoting apoptosis in vitro via activation of mitogen-activated protein kinase kinases (MEK)/extracellular signal-regulated kinase (ERK)/p38 signaling. CDKN2B-AS1 bound to mitogen-activated protein kinase (MAPK) inactivator dual-specificity phosphatase 1 (DUSP1) in CRC cells. In contrast to CDKN2B-AS1, DUSP1 promoted CRC cell proliferation, suppressed apoptosis and inactivated MEK/ERK/p38 signaling in CRC cells. Furthermore, CDKN2B-AS1 overexpression attenuated DUSP1 expression in normal colonic myofibroblasts and CRC cells. Overexpression of DUSP1 effectively countered the activation of MEK/ERK/p38 signaling induced by CDKN2B-AS1 overexpression or further blocked MEK/ERK/p38 signaling suppressed by CDKN2B-AS1 silencing. In the mouse xenograft model, CDKN2B-AS1 suppressed CRC growth, whereas DUSP1 promoted CRC growth. CDKN2B-AS1 induced cell apoptosis while suppressing EMT (epithelial-mesenchymal transition), whereas DUSP1 suppressed cell apoptosis while inducing EMT in CRC, as evidenced by the alterations in the protein levels of apoptosis and EMT markers in tumor tissue samples. CDKN2B-AS1 regulates CRC cell growth and survival by targeting MAPK inactivator DUSP1.

Photobiomodulation With Blue Laser Inhibits Bladder Cancer Progression

Blue lasers are becoming more widely used in the diagnosis and treatment of bladder cancer; however, their photobiomodulation effects on bladder cancer cells remains unclear. The purpose of the current study was to explore the photobiomodulation effect of blue laser irradiation on bladder cancer progression and the associated mechanisms. The human uroepithelial cell line SV-HUC-1 and human bladder cancer cell lines T24 and EJ were exposed to blue laser irradiation (450 nm) at various energy densities, and cell proliferation, migration, invasion, epithelial-mesenchymal transition (EMT), and the levels of the proteins associated with the MAPK pathway proteins were determined. A significant decrease in cell viability was observed in a density-dependent manner after blue laser irradiation at > 4 J/cm² in both bladder cancer cell lines. However, the blue laser did not reduce cell viability in SV-HUC-1 cells until the energy density exceeded 16 J/cm². Meanwhile, Ki67 levels, reflecting cell proliferation and senescence, were also significantly decreased after blue laser irradiation at 4 J/cm² and 8 J/cm² in the absence of cell cycle arrest. Moreover, blue laser irradiation at 4 J/cm² and 8 J/cm² caused a reduction in cell migration and invasion and also reduced the expression levels of MMP-2, MMP-9, Snail, N-cadherin, phospho-MEK and phospho-ERK, and elevated the expression levels of E-cadherin. Meanwhile ERK activator(tBHQ) significantly reversed the irradiation-induced suppression of proliferation, migration and invasion in T24 and EJ cell lines. The present study showed that blue laser irradiation inhibited bladder cancer proliferation in a density-dependent manner and inhibited bladder cancer progression by suppressing migration, invasion, and the EMT process in T24 and EJ cell lines. This inhibition was possibly mediated via suppression of the MAPK/MEK/ERK pathway. Thus, the use of a low-energy blue laser in the diagnosis and treatment of bladder cancer is possibly safe and may have an anti-tumor effect.

DUSP9, a Dual-Specificity Phosphatase with a Key Role in Cell Biology and Human Diseases

Mitogen-activated protein kinases (MAPKs) are essential for proper cell functioning as they regulate many molecular effectors. Careful regulation of MAPKs is therefore required to avoid MAPK pathway dysfunctions and pathologies. The mammalian genome encodes about 200 phosphatases, many of which dephosphorylate the MAPKs and bring them back to an inactive state. In this review, we focus on the normal and pathological functions of dual-specificity phosphatase 9 (DUSP9)/MAP kinase phosphatases-4 (MKP-4). This cytoplasmic phosphatase, which belongs to the threonine/tyrosine dual-specific phosphatase family and was first described in 1997, is known to dephosphorylate ERK1/2, p38, JNK and ASK1, and thereby to control various MAPK pathway cascades. As a consequence, DUSP9 plays a major role in human pathologies and more specifically in cardiac dysfunction, liver metabolic syndromes, diabetes, obesity and cancer including drug response and cell stemness. Here, we recapitulate the mechanism of action of DUSP9 in the cell, its levels of regulation and its roles in the most frequent human diseases, and discuss its potential as a therapeutic target.

DUSP4 alleviates LPS-induced chondrocyte injury in knee osteoarthritis via the MAPK signaling pathway

Knee osteoarthritis (KOA) is characterized by cartilage damage, and the associated pathogenesis is complex. The expression of dual specificity protein phosphatase 4 (DUSP4) is significantly decreased in osteoarthritis (OA); however, the specific role and mechanism underlying DUSP4 in OA are yet to be elucidated. ATDC5 cells were treated with lipopolysaccharide (LPS) to establish the cell injury model. The expression levels of DUSP4 were decreased in OA chondrocytes, demonstrated by reverse transcription-quantitative PCR and western blot analysis. Following overexpression of DUSP4 by cell transfection, Cell Counting Kit-8, ELISA, TUNEL and western blotting assays were used to detect the cell viability, oxidative stress, inflammation and apoptosis levels of LPS-induced ATDC5 cells. Overexpression of DUSP4 inhibited the activation of the MAPK signaling pathway, thereby reducing oxidative stress levels, inflammatory response and apoptosis in the OA cell model. The mechanisms underlying DUSP4 in OA were further explored following the addition of MAPK signaling pathway agonist, phorbol 12-myristate 13-acetate (PMA). The addition of PMA reversed the inhibitory effects of DUSP4 overexpression on oxidative stress, inflammatory response and apoptosis in cells. In summary, DUSP4 alleviated LPS-induced chondrocyte injury in KOA via the MAPK signaling pathway.

Long non-coding RNA AFAP1-AS1 promotes thyroid cancer progression by sponging miR-204-3p and upregulating DUSP4

Long non-coding RNA (lncRNA) actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1), shows crucial regulatory function in tumor progression. Nonetheless, the biological function and underlying mechanism of AFAP1-AS1 in the progression of thyroid cancer is still unclear. Expressions of AFAP1-AS1, miR-204-3p, and DUSP4 were quantified utilizing qRT-PCR and/or Western blot. In loss-of-function and gain-of-function assays, cell proliferation, migration and invasion were appraised by CCK-8 assay, wound healing assay, Transwell migration and invasion assays, respectively. Luciferase reporter assay was employed for validating the interaction between miR-204-3p and AFAP1-AS1 or the 3'UTR of dual specificity phosphatase 4 (DUSP4). AFAP1-AS1 was highly expressed in thyroid cancer tissues and cell lines. Highly expressed AFAP1-AS1 was in association with advanced TNM stage and positive lymph node metastasis. Knockdown of AFAP1-AS1 suppressed the proliferation, migration and invasion of thyroid cancer cells, and overexpression of AFAP1-AS1 induced a reversed effect. MiR-204-3p was targetedly repressed by AFAP1-AS1, and miR-204-3p could negatively regulate DUSP4 expression. AFAP1-AS1 augmented the expression of DUSP4 via repressing miR-204-3p, and the effects of AFAP1-AS1 overexpression on thyroid cancer cells were also partly abolished by miR-204-3p restoration. In summary, AFAP1-AS1 facilitates thyroid cancer cell proliferation, migration, and invasion by regulating miR-204-3p/DUSP4 axis.

Therapeutic Targeting PLK1 by ON-01910.Na Is Effective in Local Treatment of Retinoblastoma

Cell cycle deregulation is involved in the pathogenesis of many cancers and is often associated with protein kinase aberrations, including the polo-like kinase 1 (PLK1). We used retinoblastoma, an intraocular malignancy that lacks targeted therapy, as a disease model and set out to reveal targetability of PLK1 with a small molecular inhibitor ON-01910.Na. First, transcriptomic analysis on patient retinoblastoma tissues suggested that cell cycle progression was deregulated and confirmed that PLK1 pathway was upregulated. Next, antitumor activity of ON-01910.Na was investigated in both cellular and animal levels. Cytotoxicity induced by ON-01910.Na was tumor specific and dose dependent in retinoblastoma cells, while nontumor cells were minimally affected. In three-dimensional culture, ON-01910.Na demonstrated efficient drug penetrability with multilayer cell death. Posttreatment transcriptomic findings revealed that cell cycle arrest and MAPK cascade activation were induced following PLK1 inhibition and eventually resulted in apoptotic cell death. In Balb/c nude mice, a safe threshold of 0.8 nmol intravitreal dosage of ON-01910.Na was established for intraocular safety, which was demonstrated by structural integrity and functional preservation. Furthermore, intraocular and subcutaneous xenograft were significantly reduced with ON-01910.Na treatments. For the first time, we demonstrated targetability of PLK1 in retinoblastoma by efficiently causing cell cycle arrest and apoptosis. Our study is supportive that local treatment of ON-01910.Na may be a novel, effective modality benefiting patients with PLK1-aberrant tumors.