Regulation of human mitogen-activated protein kinase 15 (extracellular signal-regulated kinase 7/8) and its functions: A recent update

Atypical MAPKs in cancer

Impaired kinase signalling leads to various diseases, including cancer. At the same time, kinases make up the majority of the druggable genome and targeting kinase activity has proven to be a successful first-line therapy for many cancers. Among the best-studied kinases are the mitogen-activated protein kinases (MAPKs), which regulate cell proliferation, differentiation, motility, and survival. However, the MAPK family also contains the atypical members ERK3 (MAPK6), ERK4 (MAPK4), ERK7/ERK8 (MAPK15), and NLK that are functionally and structurally different from their conventional family members and have long been neglected. Nevertheless, in recent years, important roles in carcinogenesis, actin cytoskeleton regulation and the immune system have been discovered, underlining the physiological importance of atypical MAPKs and the need to better understand their functions. This review highlights the distinctive features of the atypical MAPKs and summarizes the evidence on their regulation, physiological roles, and potential targeting strategies for cancer therapies.

Protein Kinases as Mediators for miRNA Modulation of Neuropathic Pain

Neuropathic pain is a chronic condition resulting from injury or dysfunction in the somatosensory nervous system, which leads to persistent pain and a significant impairment of quality of life. Research has highlighted the complex molecular mechanisms that underlie neuropathic pain and has begun to delineate the roles of microRNAs (miRNAs) in modulating pain pathways. miRNAs, which are small non-coding RNAs that regulate gene expression post-transcriptionally, have been shown to influence key cellular processes, including neuroinflammation, neuronal excitability, and synaptic plasticity. These processes contribute to the persistence of neuropathic pain, and miRNAs have emerged as critical regulators of pain behaviors by modulating signaling pathways that control pain sensitivity. miRNAs can influence neuropathic pain by targeting genes that encode protein kinases involved in pain signaling. This review focuses on miRNAs that have been demonstrated to modulate neuropathic pain behavior through their effects on protein kinases or their immediate upstream regulators. The relationship between miRNAs and neuropathic pain behaviors is characterized as either an upregulation or a downregulation of miRNA levels that leads to a reduction in neuropathic pain. In the case of miRNA upregulation resulting in an alleviation of neuropathic pain behaviors, protein kinases exhibit a positive correlation with neuropathic pain, whereas decreased protein kinase levels correlate with diminished neuropathic pain behaviors. The only exception is GRK2, which shows an inverse correlation with neuropathic pain. In the case of miRNA downregulation resulting in a reduction in neuropathic pain behaviors, protein kinases display mixed relationships to neuropathic pain, with some kinases exhibiting positive correlation, while others exhibit negative correlation. By exploring how protein kinases mediate miRNA modulation of neuropathic pain, valuable insight may be gained into the pathophysiology of neuropathic pain, offering potential therapeutic targets for developing more effective strategies for pain management.

Comparative analysis of BAG1 and BAG2: Insights into their structures, functions and implications in disease pathogenesis

As BAG family members, Bcl-2 associated athanogene family protein 1 (BAG1) and 2 (BAG2) are implicated in multiple cellular processes, including apoptosis, autophagy, protein folding and homeostasis. Although structurally similar, they considerably differ in many ways. Unlike BAG2, BAG1 has four isoforms (BAG1L, BAG1M, BAG1S and BAG1 p29) displaying different expression features and functional patterns. BAG1 and BAG2 play different cellular functions by interacting with different molecules to participate in the regulation of various diseases, including cancer/tumor and neurodegenerative diseases. Commonly, BAG1 acts as a protective factor to predict a good prognosis of patients with some types of cancer or a risk factor in some other cancers, while BAG2 is regarded as a risk factor to promote cancer/tumor progression. In neurodegenerative diseases, BAG2 commonly acts as a neuroprotective factor. In this review, we summarized the differences in molacular structure and biological function between BAG1 and BAG2, as well as the influences of them on pathogenesis of diseases, and explore the prospects for their clinical therapy application by specifying the activators and inhibitors of BAG1 and BAG2, which might provide a better understanding of the underlying pathogenesis and developing the targeted therapy strategies for diseases.

Ameliorative effects of sinapic acid against vancomycin-induced testicular oxidative damage, apoptosis, inflammation, testicular histopathologic disorders and decreased epididymal sperm quality

In this study, it was aimed to determine the effect of sinapic acid (SNP), a polyphenol with antioxidant, anti-inflammatory and antibacterial properties, on testicular damage caused by vancomycin (VCM), a widely used antibiotic against gram positive bacteria. A total of 35 male Sprague Dawley rats were used in the study, divided into five groups: control, VCM, SNP, VCM + SNP 10, and VCM + SNP 20. Following a week of oral administration, the rats were euthanized under sevoflurane anesthesia. While the VCM group had a significant increase in MDA levels, the SNP administration inhibited the increase in MDA levels. VCM led to a significant decrease in GSH levels, SOD, CAT, and GPx activity in the testicular tissue of rats, while SNP administration increased these antioxidant levels. SNP administration decreased the mRNA expression levels of VCM induced Nrf-2, HO-1, and NQO1 in testicular tissue while increasing the levels of MAPK14, MAPK15, JNK, P53, Apaf-1, Caspase-3, Caspase-6, Caspase-9, and Beclin-1 mRNA transcript levels. The VCM group showed a significant increase in Bax and NF-κB levels in testicular tissue, while Bcl-2 levels decreased. VCM significantly decreased sperm motility and increased the percentage of damaged sperm in rats. Histopathological results revealed that VCM caused disruption of basement membranes and disorganization of seminiferous tubules, but SNP administration preserved testicular histology. As a result, VCM increased oxidative stress, apoptosis, and autophagy in the testicular tissue of rats, altered testicular histopathology, and decreased sperm quality, while SNP decreased these effects.

A Comprehensive Review of Protein Biomarkers for Invasive Lung Cancer

Invasion and metastasis are important hallmarks of lung cancer, and affect patients' survival. Early diagnostics of metastatic potential are important for treatment management. Recent findings suggest that the transition to an invasive phenotype causes changes in the expression of 700-800 genes. In this context, the biomarkers restricted to the specific type of cancer, like lung cancer, are often overlooked. Some well-known protein biomarkers correlate with the progression of the disease and the immunogenicity of the tumor. Most of these biomarkers are not exclusive to lung cancer because of their significant role in tumorigenesis. The dysregulation of others does not necessarily indicate cell invasiveness, as they play an active role in cell division. Clinical studies of lung cancer use protein biomarkers to assess the invasiveness of cancer cells for therapeutic purposes. However, there is still a need to discover new biomarkers for lung cancer. In the future, minimally invasive techniques, such as blood or saliva analyses, may be sufficient for this purpose. Many researchers suggest unconventional biomarkers, like circulating nucleic acids, exosomal proteins, and autoantibodies. This review paper aims to discuss the advantages and limitations of protein biomarkers of invasiveness in lung cancer, to assess their prognostic value, and propose novel biomarker candidates.

MAPK15 controls cellular responses to oxidative stress by regulating NRF2 activity and expression of its downstream target genes

Oxidation processes in mitochondria and different environmental insults contribute to unwarranted accumulation of reactive oxygen species (ROS). These, in turn, rapidly damage intracellular lipids, proteins, and DNA, ultimately causing aging and several human diseases. Cells have developed different and very effective systems to control ROS levels. Among these, removal of excessive amounts is guaranteed by upregulated expression of various antioxidant enzymes, through activation of the NF-E2-Related Factor 2 (NRF2) protein. Here, we show that Mitogen Activated Protein Kinase 15 (MAPK15) controls the transactivating potential of NRF2 and, in turn, the expression of its downstream target genes. Specifically, upon oxidative stress, MAPK15 is necessary to increase NRF2 expression and nuclear translocation, by inducing its activating phosphorylation, ultimately supporting transactivation of cytoprotective antioxidant genes. Lungs are continuously exposed to oxidative damages induced by environmental insults such as air pollutants and cigarette smoke. Interestingly, we demonstrate that MAPK15 is very effective in supporting NRF2-dependent antioxidant transcriptional response to cigarette smoke of epithelial lung cells. Oxidative damage induced by cigarette smoke indeed represents a leading cause of disability and death worldwide by contributing to the pathogenesis of different chronic respiratory diseases and lung cancer. Therefore, the development of novel therapeutic strategies able to modulate cellular responses to oxidative stress would be highly beneficial. Our data contribute to the necessary understanding of the molecular mechanisms behind such responses and identify new potentially actionable targets.

Identification of mapk genes, and their expression profiles in response to low salinity stress, in cobia (Rachycentron canadum)

Mitogen-activated protein kinases (MAPKs) are a class of protein kinases that regulate various physiological processes, and play a crucial role in maintaining the osmotic equilibrium of fish. The objective of this study was to identify and characterize the mapk family genes in cobia (Rachycentron canadum) and examine their expression profiles under different low salinity stress regimes (acute: from 30‰ to 10‰ in 1 h, sub-chronic: from 30‰ to 10‰ over 4 d). A total of 12 cobia mapk genes (Rcmapks) were identified and cloned, including six erk subfamily genes (Rcmapk1/3/4/6/7/15), three jnk subfamily genes (Rcmapk8/9/10) and three p38 mapk subfamily genes (Rcmapk 11/13/14). Domain analysis indicated that the RcMAPKs possessed the typical domains including S_TKc and PKc_like domain. Phylogenetic analysis revealed that the Rcmapks were most closely related to those of the turbot (Scophthalmus maximus). The tissue distribution of mapk genes in adult cobia and the expression patterns of Rcmapks under different low salinity stress regimes were investigated using quantitative real-time PCR (qRT-PCR). The results revealed that Rcmapk3/9/10/11/13/14 exhibited a relatively broad expression distribution across 14 different tissues. For all these genes the highest expression level was in the brain, except for Rcmapk14 (highly expressed in the stomach, gill, and skin). The genes Rcmapk1/6/15 showed significantly higher expression in the testis. Under acute low salinity stress, expression of Rcmapk1/3/6/7/9/11/13/14 was significantly altered in the gill, intestine, and trunk kidney, however, the aforementioned genes exhibited very different expression patterns among the three tissues. In the gill, most of the genes from the erk (Rcmapk3/6/7) and p38 mapk subfamily (Rcmapk11/13/14) were significantly up-regulated at almost all the time points (P < 0.05); Similarly, the expression of Rcmapk3/9/11/13/14 genes were significantly increased in the trunk kidney; while in the intestine, most of the altered genes (Rcmapk6/7/9/11/13/14) were significantly down-regulated at 1 h. Following the sub-chronic low salinity stress, expression of Rcmapk1/3/6/7/9/11/13/14 genes were significantly altered in all three tissues. These findings provide important reference data for elucidating the roles of cobia mapk family genes in response to low salinity stress.

SIRT2 regulates apoptosis by inducing mitophagy in sheep cumulus cells

Cumulus cells surrounding oocytes furnish nutritional support crucial for oocyte maturation in vitro, and thereby enhance oocyte quality significantly. Our previous studies affirmed the role of SIRT2 in regulation of mitochondrial function in sheep granulosa cells. However, the effect of SIRT2 action on mitophagy in these cells remain unclear. Here, RNA-seq was used to scrutinize pathways where differentially expressed genes (DEGs) are enriched following SIRT2 knockdown in cumulus cells. Prior to SIRT2 knock down, cumulus cells were treated with the mitophagy inhibitor Mdivi-1. Potential mechanisms by which SIRT2 affects apoptosis via mitophagy were explored. Results indicated that DEGs after SIRT2 knockdown were enriched in various pathways including mitochondria, mitophagy, and apoptosis. The expression levels of CASP3/CASP9 were significantly increased after mitophagy activation (P < 0.01), whereas inhibition of mitophagy had no effect on apoptosis (P > 0.05). Pretreatment of cumulus cells with Mdivi-1 prior to SIRT2 knockdown significantly reduced the expression of mitophagy-related genes, the number of autolysosomes, the expression of CASP3/CASP9, and the levels of Ca2+ and cytochrome C (P < 0.05). In addition, an improvement in mitochondrial morphology and increases in ATP levels and mitochondrial DNA (mtDNA) copy numbers were observed. Interestingly, double knockdown of SIRT2 and MAPK15 was found to reverse increased mitophagy and apoptosis activity caused by SIRT2 knockdown. Our findings indicate that SIRT2 modulate apoptosis in cumulus cells by regulating mitophagy, with MAPK15 likely playing a pivotal role in this process.

Protective effect of Lizhong Pill on nonsteroidal anti-inflammatory drug-induced gastric mucosal injury in rats: Possible involvement of TNF and IL-17 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine formula Lizhong Pill (LZP) and its herbal constituents are frequently utilized in Asian (China, Saudi Arabia, India, Japan, etc.) and some European (Russia, Sweden, UK, etc.) nations to treat various gastrointestinal ailments.

AIM OF THE STUDY

This study aimed to investigate the protective impact and potential mechanism of LZP against indomethacin (IND)-induced gastric mucosal injury in rats.

MATERIAL AND METHODS

Using a biochemical kit, we investigated the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) in rat serum, as well as pepsin in rat stomach tissue, using an IND-induced rat model of gastric mucosal injury. Various imaging tools, including HE staining, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), were used to examine the gastric mucosa's surface morphology and ultrastructure. Furthermore, molecular docking was employed to predict the binding capacity of the primary bioactive components of LZP to the critical molecular protein targets in the IL-17 and TNF signaling pathways. At the same time, immunofluorescence was used to determine the protein expressions of CASP3, VCAM1, MAPK15, MMP3, IL-17RA, and TNFR1.

RESULTS

The present study demonstrates that LZP (3.75 and 7.50 g/kg) significantly reduces the gastric mucosal injury index induced by IND. This effect is evidenced by the improved morphology, surface, and structure of the gastric mucosa, as determined by HE, SEM, and TEM findings. Additionally, 3.75 and 7.50 g/kg LZP intervention significantly increased SOD and CAT contents and inhibited pepsin and GST activities. Molecular docking analysis revealed that the small molecular components of LZP can bind spontaneously to crucial proteins involved in the IL-17 and TNF signaling pathways, including MAPK15, MMP3, VCAM1, and CASP3. The immunofluorescence findings proved that LZP (3.75 and 7.50 g/kg) can inhibit the protein expressions of MAPK15, MMP3, VCAM1, CASP3, IL-17RA, and TNFR1.

CONCLUSIONS

Our investigation findings demonstrate that LZP can potentially ameliorate IND-induced damage to the gastric mucosa by inhibiting IL-17 and TNF signaling pathways. These results offer encouraging support for using alternative medicine to manage drug-induced gastric mucosal injury.

Mitogen-Activated Protein Kinase 15 Is a New Predictive Biomarker and Potential Therapeutic Target for Ovarian Cancer

Mitogen-activated protein kinase 15 (MAPK15) has been reported to be associated with several cancers. This study aimed to explore for the first time on the relationship between MAPK15 expression and cancer progression/drug responsiveness in ovarian carcinoma. To this end, MAPK15 expression level was examined by immunohistochemistry (IHC) staining of an ovarian tissue array (10 normal and 70 malignant samples). Drug sensitivity of ovarian cancer cell lines (including OVCAR3 and SKOV3) was measured by MTS assay. The modulation of MAPK15 expression in OVCAR3 and SKOV3 was verified by immunoblot and real-time PCR analyses. The prognostic value of MAPK15 in ovarian cancer patients was assessed using the Kaplan-Meier Plotter database and Gene Expression Omnibus (GEO) datasets. The IHC results showed that MAPK15 expression was negatively associated with tumor grade, TNM stage, tumor size, and regional lymph node metastasis of ovarian carcinoma. Importantly, overexpressing MAPK15 increased cisplatin toxicity in ovarian carcinoma cells and online database analysis indicated that patients with high MAPK15 expression had favorable prognosis with/without chemotherapy. Taken together, our results indicate that a decreased MAPK15 expression is associated with advanced-stage ovarian cancer and unfavorable survival outcomes. MAPK15 may be a new biomarker for ovarian cancer, and the encouraging therapeutic strategy would be found by combining the regulation of MAPK15 expression.

The Atypical MAP Kinase MAPK15 Is Required for Lung Adenocarcinoma Metastasis via Its Interaction with NF-κB p50 Subunit and Transcriptional Regulation of Prostaglandin E2 Receptor EP3 Subtype

Studying the relatively underexplored atypical MAP Kinase MAPK15 on cancer progression/patient outcomes and its potential transcriptional regulation of downstream genes would be highly valuable for the diagnosis, prognosis, and potential oncotherapy of malignant tumors such as lung adenocarcinoma (LUAD). Here, the expression of MAPK15 in LUAD was detected by immunohistochemistry and its correlation with clinical parameters such as lymph node metastasis and clinical stage was analyzed. The correlation between the prostaglandin E2 receptor EP3 subtype (EP3) and MAPK15 expression in LUAD tissues was examined, and the transcriptional regulation of EP3 and cell migration by MAPK15 in LUAD cell lines were studied using the luciferase reporter assay, immunoblot analysis, qRT-PCR, and transwell assay. We found that MAPK15 is highly expressed in LUAD with lymph node metastasis. In addition, EP3 is positively correlated with the expression of MAPK15 in LUAD tissues, and we confirmed that MAPK15 transcriptionally regulates the expression of EP3. Upon the knockdown of MAPK15, the expression of EP3 was down-regulated and the cell migration ability was decreased in vitro; similarly, the mesenteric metastasis ability of the MAPK15 knockdown cells was inhibited in in vivo animal experiments. Mechanistically, we demonstrate for the first time that MAPK15 interacts with NF-κB p50 and enters the nucleus, and NF-κB p50 binds to the EP3 promoter and transcriptionally regulates the expression of EP3. Taken together, we show that a novel atypical MAPK and NF-κB subunit interaction promotes LUAD cell migration through transcriptional regulation of EP3, and higher MAPK15 level is associated with lymph node metastasis in patients with LUAD.

Morin ameliorates methotrexate-induced hepatotoxicity via targeting Nrf2/HO-1 and Bax/Bcl2/Caspase-3 signaling pathways

BACKGROUND

Organ toxicity limits the therapeutic efficacy of methotrexate (MTX), an anti-metabolite therapeutic that is frequently used as an anti-cancer and immunosuppressive medicine. Hepatocellular toxicity is among the most severe side effects of long-term MTX use. The present study unveils new confirmations as regards the remedial effects of morin on MTX-induced hepatocellular injury through regulation of oxidative stress, apoptosis and MAPK signaling.

METHODS AND RESULTS

Rats were subjected to oral treatment of morin (50 and 100 mg/kg body weight) for 10 days. Hepatotoxicity was induced by single intraperitoneal injection of MTX (20 mg/kg body weight) on the 5th day. MTX related hepatic injury was associated with increased MDA while decreased GSH levels, the activities of endogen antioxidants (glutathione peroxidase, superoxide dismutase and catalase) and mRNA levels of HO-1 and Nrf2 in the hepatic tissue. MTX treatment also resulted in apoptosis in the liver tissue via increasing mRNA transcript levels of Bax, caspase-3, Apaf-1 and downregulation of Bcl-2. Conversely, treatment with morin at different doses (50 and 100 mg/kg) considerably mitigated MTX-induced oxidative stress and apoptosis in the liver tissue. Morin also mitigated MTX-induced increases of ALT, ALP and AST levels, downregulated mRNA expressions of matrix metalloproteinases (MMP-2 and MMP-9), MAPK14 and MAPK15, JNK, Akt2 and FOXO1 genes.

CONCLUSION

According to the findings of this study, morin may be a potential way to shield the liver tissue from the oxidative damage and apoptosis.

Evolution of mitogen-activated protein kinase family and their immune function in Apostichopus japonicus

The mitogen-activated protein kinase family plays an important role in cell differentiation, growth, proliferation, and survival. However, the current research on the mitogen-activated protein kinase (MAPK) family in invertebrates is limited to the individual gene, and the analysis has not been conducted at the family level. In the present study, echinoderm MAPK family was identified by genomic screening, and five members, including three ERK subfamily members, one c-Jun N-terminal kinase (JNK) subfamily, and one p38-MAPK member were detected. Phylogenetic analysis showed that three MAPK subfamilies were separated into three separated clusters, and ERK subfamily appeared earlier than the other two subfamilies. Synteny analysis revealed that the p38 subfamily might be derived from the continuous gene duplication events of MAPK14 subfamily in invertebrates, which displayed genome expansion via gene duplication in vertebrates. The role of MAPK family in echinoderm immune defense was determined by investigating the expression profiles of MAPKs in Vibrio splendidus-challenged Apostichopus japonicus and LPS-exposed coelomocytes. The result showed that five MAPK members displayed induced expression profiles both in vitro and in vivo, and the peak expression was detected at different time points. Our study provides new insights into the evolutionary history of the MAPK family and show the similar immune function among MAPK members.

Blockade of the orexin receptors in the ventral tegmental area could attenuate the stress-induced analgesia: A behavioral and molecular study

Exposure to stressful stimuli induces various physiological and behavioral responses, affects pain perception, and alters gene expression. Stress elicits an analgesic effect in laboratory animals, termed the "stress-induced analgesia" (SIA). Orexin neuropeptides, processed from pre-pro-orexin in the hypothalamus, release during stress and are known to be antinociceptive. The current study examined the modulatory role of the ventral tegmental area (VTA) orexinergic system in the restraint SIA and extracellular signal-regulated kinase (ERK) activation in the nucleus accumbens (NAc). Adult male Wistar rats were subjected to intra-VTA injection of orexin-1 and -2 receptor antagonists (SB334867 and TCS OX2 29; 1, 3, 10, and 30 nmol/0.3 μl, respectively) five min before a 3-h period of exposure to restraint stress (RS). Western blot analysis was also used to assess the levels of ERK and phosphorylated ERK (p-ERK) in the NAc tissues. RS exposure produced an analgesic response to the thermal pain model (Tail-flick test). RS-induced antinociception was inhibited by intra-VTA administration of SB334867 and TCS OX2 29. Moreover, in the molecular study, exposure to forced swim stress (FSS) and RS significantly enhanced the p-ERK/ERK ratio. Blockade of both orexin receptors diminished the p-ERK/ERK ratio, but this decrease was significant only in the FSS group of animals that received TCS OX2 29. Collectively, the present findings suggested the functional roles of intra-VTA orexin receptors and ERK signaling in the SIA.

Transcriptional upregulation of MAPK15 by NF-κB signaling boosts the efficacy of combination therapy with cisplatin and TNF-α

The efficacy of cisplatin in treating advanced non-small cell lung cancer is limited mainly because of insensitivity and/or acquired resistance. MAPK15, previously shown by us to enhance the sensitivity of the anti-cancer drug arsenic trioxide, could also enhance the sensitivity of other anti-cancer drugs. Here, we explore the potential role of MAPK15 in chemosensitivity to cisplatin in human lung cancer cells. Our results indicated that the expression level of MAPK15 was positively correlated with cisplatin sensitivity through affecting the DNA repair capacity of cisplatin-treated cells. The expression of MAPK15 was transcriptionally regulated by the TNF-α-activated NF-κB signaling pathway, and TNF-α synergized with cisplatin, in a MAPK15-dependent manner, to exert cytotoxicity in vitro and in vivo. Therefore, levels of TNF-α dictate the responsiveness/sensitivity of lung cancer cells to cisplatin by transcriptionally upregulating MAPK15 to enhance chemosensitivity, suggesting manipulation of MAPK15 as a strategy to improve the therapeutic efficacy of chemotherapeutic drugs.

Effects of CYP3A43 Expression on Cell Proliferation and Migration of Lung Adenocarcinoma and Its Clinical Significance

The cytochrome P450s (CYP450s) include key oxidative enzymes involved in the metabolism of various carcinogens and anticancer drugs. Bioinformatic studies have demonstrated the association of CYP3A43 with liver cancer and ovarian cancer. However, the biological function of CYP3A43 in tumor progression remains unclear. To further reveal the role of CYP3A43 in tumor progression, we first analyzed the data from the UALCAN database and found that CYP3A43 was negatively correlated to the cancer staging and lymph node metastasis of lung adenocarcinoma (LUAD). We established stable CYP3A43-knockdown LUAD H1299 cell line and found that its knockdown enhanced cell proliferation, colony formation, and migration in vitro, and promoted the growth of tumor xenograft in vivo. Interestingly, when CYP3A43 was ectopically-expressed in the LUAD cell lines, decreased cell proliferation and ERK1/2 phosphorylation level were observed. Lastly, we also identified CYP3A43 co-expressed genes in LUAD from LinkedOmics database followed by GO and KEGG analyses. In conclusion, our results indicate the unprecedented role of CYP3A43 in the suppression of LUAD and provide new possibilities for targeted therapy of this life-threatening disease.

The Revelation of Continuously Organized, Co-Overexpressed Protein-Coding Genes with Roles in Cellular Communications in Breast Cancer

Many human cancers, including breast cancer, are polygenic and involve the co-dysregulation of multiple regulatory molecules and pathways. Though the overexpression of genes and amplified chromosomal regions have been closely linked in breast cancer, the notion of the co-upregulation of genes at a single locus remains poorly described. Here, we describe the co-overexpression of 34 continuously organized protein-coding genes with diverse functions at 8q.24.3(143437655-144326919) in breast and other cancer types, the CanCord34 genes. In total, 10 out of 34 genes have not been reported to be overexpressed in breast cancer. Interestingly, the overexpression of CanCord34 genes is not necessarily associated with genomic amplification and is independent of hormonal or HER2 status in breast cancer. CanCord34 genes exhibit diverse known and predicted functions, including enzymatic activities, cell viability, multipotency, cancer stem cells, and secretory activities, including extracellular vesicles. The co-overexpression of 33 of the CanCord34 genes in a multivariant analysis was correlated with poor survival among patients with breast cancer. The analysis of the genome-wide RNAi functional screening, cell dependency fitness, and breast cancer stem cell databases indicated that three diverse overexpressed CanCord34 genes, including a component of spliceosome PUF60, a component of exosome complex EXOSC4, and a ribosomal biogenesis factor BOP1, shared roles in cell viability, cell fitness, and stem cell phenotypes. In addition, 17 of the CanCord34 genes were found in the microvesicles (MVs) secreted from the mesenchymal stem cells that were primed with MDA-MB-231 breast cancer cells. Since these MVs were important in the chemoresistance and dedifferentiation of breast cancer cells into cancer stem cells, these findings highlight the significance of the CanCord34 genes in cellular communications. In brief, the persistent co-overexpression of CanCord34 genes with diverse functions can lead to the dysregulation of complementary functions in breast cancer. In brief, the present study provides new insights into the polygenic nature of breast cancer and opens new research avenues for basic, preclinical, and therapeutic studies in human cancer.

MAPK15 protects from oxidative stress-dependent cellular senescence by inducing the mitophagic process

Mitochondria are the major source of reactive oxygen species (ROS), whose aberrant production by dysfunctional mitochondria leads to oxidative stress, thus contributing to aging as well as neurodegenerative disorders and cancer. Cells efficiently eliminate damaged mitochondria through a selective type of autophagy, named mitophagy. Here, we demonstrate the involvement of the atypical MAP kinase family member MAPK15 in cellular senescence, by preserving mitochondrial quality, thanks to its ability to control mitophagy and, therefore, prevent oxidative stress. We indeed demonstrate that reduced MAPK15 expression strongly decreases mitochondrial respiration and ATP production, while increasing mitochondrial ROS levels. We show that MAPK15 controls the mitophagic process by stimulating ULK1‐dependent PRKN Ser¹⁰⁸ phosphorylation and inducing the recruitment of damaged mitochondria to autophagosomal and lysosomal compartments, thus leading to a reduction of their mass, but also by participating in the reorganization of the mitochondrial network that usually anticipates their disposal. Consequently, MAPK15‐dependent mitophagy protects cells from accumulating nuclear DNA damage due to mitochondrial ROS and, consequently, from senescence deriving from this chronic DNA insult. Indeed, we ultimately demonstrate that MAPK15 protects primary human airway epithelial cells from senescence, establishing a new specific role for MAPK15 in controlling mitochondrial fitness by efficient disposal of old and damaged organelles and suggesting this kinase as a new potential therapeutic target in diverse age‐associated human diseases.

Icariin Promotes In Vitro Cardiomyocyte Proliferation and Differentiation in Human Bone Marrow-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) are the excellent candidates in myocardial regeneration given their easy accessibility, low immunogenicity and high potential for cardiomyocyte differentiation. This work focused on investigating the role of icariin, a main active component of the Traditional Chinese herb epimedium, in human bone marrow-derived MSCs (BMSCs) proliferation and differentiation into cardiomyocytes In Vitro. Human BMSCs were cultivated In Vitro, and MTT assay was conducted to measure their proliferation. On this basis, we selected the optimal icariin dose for promoting the proliferation to induce cardiomyocyte differentiation of MSCs, which were pretreated with or without 5-azacytidine (5-Aza). Cardiac-specific cardiac troponin I (cTnI) and connexin 43 (Cx43)-positive cells were detected by immunofluorescent staining. The differentiation ratio of MSCs was examined by flow cytometry. This study measured early cardiac transcription factors (TFs) Nkx2.5 and GATA4 levels through RT-PCR and Western blotting (WB). As a result, icariin increased MSC proliferation dependent on its dose, and the optimal dose was determined to be 80 μg/l. Furthermore, MSCs showed minimal cardiomyogenic differentiation when induced by icariin alone as confirmed by the expression of cardiac-related markers. Moreover, a synergic interaction was observed when icariin and 5-Aza cooperated to induce cardiomyocyte differentiation of MSCs. In conclusion, Icariin stimulates proliferation and facilitates cardiomyocyte differentiation of MSCs In Vitro and may be potentially used as a new method for enhancing the MSCs efficacy in cardiovascular disease.

Protein Kinase A-Mediated Effects of Protein Kinase C Partial Agonist 5-(Hydroxymethyl)Isophthalate 1a3 in Colorectal Cancer Cells

Colorectal cancer is the third most commonly occurring cancer in men and the second in women. The global burden of colorectal cancer is projected to increase to over 2 million new cases with over 1 million deaths within the next 10 years, and there is a great need for new compounds with novel mechanisms of action. Our group has developed protein kinase C (PKC)-modulating isophthalic acid derivatives that induce cytotoxicity toward human cervical and prostate cancer cell lines. In this study, we investigated the effects of 5-(hydroxymethyl)isophthalate 1a3 (HMI-1a3) on colorectal cancer cell lines (Caco-2, Colo205, and HT29). HMI-1a3 inhibited cell proliferation, decreased cell viability, and induced an apoptotic response in all studied cell lines. These effects, however, were independent of PKC. Using serine/threonine kinome profiling and pharmacological kinase inhibitors, we identified activation of the cAMP/PKA pathway as a new mechanism of action for HMI-1a3-induced anticancer activity in colorectal cancer cell lines. Our current results strengthen the hypothesis for HMI-1a3 as a potential anticancer agent against various malignancies. SIGNIFICANCE STATEMENT: Colorectal cancer (CRC) is a common solid organ malignancy. This study demonstrates that the protein kinase C (PKC)-C1 domain-targeted isophthalatic acid derivative 5-(hydroxymethyl)isophthalate 1a3 (HMI-1a3) has anticancer activity on CRC cell lines independently of PKC. We identified PKA activation as a mechanism of HMI-1a3-induced anticancer effects. The results reveal a new anticancer mechanism of action for the partial PKC agonist HMI-1a3 and thus provide new insights for the development of PKC and PKA modulators for cancer therapy.

Regulation of Mitogen-Activated Protein Kinase Signaling Pathways by the Ubiquitin-Proteasome System and Its Pharmacological Potential

Mitogen-activated protein kinase (MAPK) cascades are evolutionarily conserved signaling pathways that play essential roles in transducing extracellular environmental signals into diverse cellular responses to maintain homeostasis. These pathways are classically organized into an architecture of three sequentially acting protein kinases: a MAPK kinase kinase that phosphorylates and activates a MAPK kinase, which in turn phosphorylates and activates the effector MAPK. The activity of MAPKs is tightly regulated by phosphorylation of their activation loop, which can be modulated by positive and negative feedback mechanisms to control the amplitude and duration of the signal. The signaling outcomes of MAPK pathways are further regulated by interactions of MAPKs with scaffolding and regulatory proteins. Accumulating evidence indicates that, in addition to these mechanisms, MAPK signaling is commonly regulated by ubiquitin-proteasome system (UPS)-mediated control of the stability and abundance of MAPK pathway components. Notably, the biologic activity of some MAPKs appears to be regulated mainly at the level of protein turnover. Recent studies have started to explore the potential of targeted protein degradation as a powerful strategy to investigate the biologic functions of individual MAPK pathway components and as a new therapeutic approach to overcome resistance to current small-molecule kinase inhibitors. Here, we comprehensively review the mechanisms, physiologic importance, and pharmacological potential of UPS-mediated protein degradation in the control of MAPK signaling. SIGNIFICANCE STATEMENT: Accumulating evidence highlights the importance of targeted protein degradation by the ubiquitin-proteasome system in regulating and fine-tuning the signaling output of mitogen-activated protein kinase (MAPK) pathways. Manipulating protein levels of MAPK cascade components may provide a novel approach for the development of selective pharmacological tools and therapeutics.

Identification, Characterization, and Expression Analysis Reveal Diverse Regulated Roles of Three MAPK Genes in Chlamys farreri Under Heat Stress

Mitogen-activated protein kinase (MAPK) cascades are fundamental signal transduction modules in all eukaryotic organisms, participating growth and development, as well as stress response. In the present study, three MAPK genes were successfully identified from the genome of Chlamys farreri, respectively, named CfERK1/2, CfJNK, and Cfp38, and only one copy of ERK, JNK, and p38 were detected. Domain analysis indicated that CfMAPKs possessed the typical domains, including S_TKc, Pkinase, and PKc_like domain. Phylogenetic analysis showed that three CfMAPKs of MAPK subfamilies exists in the common ancestor of vertebrates and invertebrates. All CfMAPKs specifically expressed during larval development and in adult tissues, and the expression level of CfERK1/2 and Cfp38 was apparently higher than that of CfJNK. Under heat stress, the expression of CfERK1/2 and Cfp38 were significantly downregulated and then upregulated in four tissues, while the expression of CfJNK increased in all tissues; these different expression patterns suggested a different molecular mechanism of CfMAPKs for bivalves to adapt to temperature changes. The diversity of CfMAPKs and their specific expression patterns provide valuable information for better understanding of the functions of MAPK cascades in bivalves.

IGF1R and MAPK15 Emerge as Potential Targets of Pentabromobenzylisothioureas in Lung Neuroendocrine Neoplasms

Pentabromobenzylisothioureas are antitumor agents with diverse properties, including the inhibition of MAPK15, IGF1R and PKD1 kinases. Their dysregulation has been implicated in the pathogenesis of several cancers, including bronchopulmonary neuroendocrine neoplasms (BP-NEN). The present study assesses the antitumor potential of ZKKs, a series of pentabromobenzylisothioureas, on the growth of the lung carcinoid H727 cell line. It also evaluates the expression of MAPK15, IGF1R and PKD1 kinases in different BP-NENs. The viability of the H727 cell line was assessed by colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) and its proliferation by BrdU (5-bromo-2′-deoxyuridine) assay. Tissue kinase expression was measured using TaqMan-based RT-PCR and immunohistochemistry. ZKKs (10⁻⁴ to 10⁻⁵ M) strongly inhibited H727 cell viability and proliferation and their antineoplastic effects correlated with their concentrations (p < 0.001). IGF1R and MAPK15 were expressed at high levels in all subtypes of BP-NENs. In addition, the SCLC (small cell lung carcinoma) patients demonstrated higher mRNA levels of IGF1R (p = 0.010) and MAPK15 (p = 0.040) than the other BP-NEN groups. BP-NENs were characterized by low PKD1 expression, and lung neuroendocrine cancers demonstrated lower PKD1 mRNA levels than carcinoids (p = 0.003). ZKKs may suppress BP-NEN growth by inhibiting protein kinase activity. Our results suggest also a possible link between high IGF1R and MAPK15 expression and the aggressive phenotype of BP-NEN tumors.

Identification of atypical mitogen-activated protein kinase MAPK4 as a novel regulator in acute lung injury

Background

Acute lung injury (ALI) is a serious disease with highly morbidity and mortality that causes serious health problems worldwide. Atypical mitogen activated protein kinases (MAPKs) play critical roles in the development of tissues and have been proposed as promising therapeutic targets for various diseases. However, the potential role of atypical MAPKs in ALI remains elusive. In this study, we investigated the role of atypical MAPKs family member MAPK4 in ALI using LPS-induced murine ALI model.

Results

We found that MAPK4 deficiency mice exhibited prolonged survival time after LPS challenge, accompanied by alleviated pathology in lung tissues, decreased levels of pro-inflammatory cytokines and altered composition of immune cells in BALF. Furthermore, the transduction of related signaling pathways, including MK5, AKT, JNK, and p38 MAPK pathways, was reduced obviously in LPS-treated MAPK4^−/− mice. Notably, the expression of MAPK4 was up-regulated in lung tissues of ALI model, which was not related with MAPK4 promoter methylation, but negatively orchestrated by transcriptional factors NFKB1 and NR3C1. Further studies have shown that the expression of MAPK4 was also increased in LPS-treated macrophages. Meanwhile, MAPK4 deficiency reduced the expression of related pro-inflammatory cytokines in macrophage in response to LPS treatment. Finally, MAPK4 knockdown using shRNA pre-treatment could ameliorate the pathology of lung tissues and prolong the survival time of mice after LPS challenge.

Conclusions

Collectively, these findings reveal an important biological function of atypical MAPK in mediating the pathology of ALI, indicating that MAPK4 might be a novel potential therapeutic target for ALI treatment.

Metastasis-associated gene MAPK15 promotes the migration and invasion of osteosarcoma cells via the c-Jun/MMPs pathway

Osteosarcoma (OS) is the most common and destructive primary bone malignancy to affect children and adolescents. Metastases remain the primary cause of death in patients with OS. In the present study, weight gene co-expressed network analysis (WGCNA) and differentially-expressed gene analysis were used to identify key genes associated with the metastasis of OS. Reverse transcription-quantitative PCR and immunohistochemical staining were then used to detect the expression levels of these key genes in OS tissues, and to determine the hub genes of interest. Wound-healing and transwell assays, in addition to a lung metastasis model, were used to detect the effects of the hub genes on OS cell proliferation and metastasis in vitro and in vivo. Using WGCNA and differential expression analysis, deleted in lung and esophageal cancer protein 1 (DLEC1), Forkhead box J1 (FOXJ1) and mitogen-activated protein kinase 15 (MAPK15) were predicted to be key metastasis-associated genes, and highly expressed in metastatic OS tissues; among them, the protein and mRNA expression levels of MAPK15 were most significantly increased in our OS tissues from patients who exhibited metastases at diagnosis, and thus MAPK15 was determined to be a metastasis-associated hub gene to further study. Furthermore, inhibiting MAPK15 expression significantly decreased OS cell metastasis in vitro and in vivo, as well as suppressing c-Jun/matrix metalloproteinase (MMP)-associated pathways. Overexpression of MAPK15 activated the c-Jun/MMPs pathway and promoted OS cell metastasis, while inhibition of c-Jun blocked this effect. Taken together, MAPK15 was indicated to be an OS metastasis-associated gene, and was confirmed to promote the migration and invasion of OS cells via the c-Jun/MMP pathway. MAPK15 may therefore be an effective target for the treatment of OS.

Cadmium telluride quantum dot-exposed human bronchial epithelial cells: a further study of the cellular response by proteomics

Quantum dots (QDs) are luminescent nanoparticles with superior versatility. In this regard, cadmium telluride (CdTe) QDs have been widely used for various bioimaging applications. Although these nano-Cd containing particles can be capped with shells to reduce their cytotoxicity, these shells would be gradually disintegrated after a certain period of time, thereby inevitably exerting nanotoxicity. Previously, we showed that treatment of human bronchial epithelial BEAS-2B cells with uncapped CdTe QDs (520Q, 580Q and 730Q with emission maximum at 520, 580 and 730 nm, respectively) elicited dose-dependent cytotoxicity for 520Q and 580Q (<5 nm), while 730Q (>5 nm) elicited negligible cytotoxicity. In order to gain a more global perspective on the action mechanism of these nano-Cd particles, here, we further characterized the proteome response of BEAS-2B when challenged with the above QDs. Interestingly, among the three nano-Cd particles, we observed that 520Q and 580Q treatment altered the BEAS-2B proteome significantly in a very similar magnitude while 730Q has no obvious impact at all, as compared with the untreated control. Notably, the treatment of BEAS-2B with glutathione before nano-Cd particles abrogated the induction/repression of differentially expressed proteins and prevented cell death. Taken together, our findings show that uncapped CdTe nanoparticles (520Q and 580Q) induce oxidative stress in human bronchial epithelial cells, and the similarly altered protein signatures also suggest potential mitotoxicity and common cellular and detoxification responses upon exposure of lung cells to these two QDs. On the other hand, 730Q may exert a more noticeable effect after long-term exposure, but not upon transient exposure.

Extracellular-Signal Regulated Kinase: A Central Molecule Driving Epithelial-Mesenchymal Transition in Cancer

Epithelial-mesenchymal transition (EMT) is a reversible cellular process, characterized by changes in gene expression and activation of proteins, favoring the trans-differentiation of the epithelial phenotype to a mesenchymal phenotype. This process increases cell migration and invasion of tumor cells, progression of the cell cycle, and resistance to apoptosis and chemotherapy, all of which support tumor progression. One of the signaling pathways involved in tumor progression is the MAPK pathway. Within this family, the ERK subfamily of proteins is known for its contributions to EMT. The ERK subfamily is divided into typical (ERK 1/2/5), and atypical (ERK 3/4/7/8) members. These kinases are overexpressed and hyperactive in various types of cancer. They regulate diverse cellular processes such as proliferation, migration, metastasis, resistance to chemotherapy, and EMT. In this context, in vitro and in vivo assays, as well as studies in human patients, have shown that ERK favors the expression, function, and subcellular relocalization of various proteins that regulate EMT, thus promoting tumor progression. In this review, we discuss the mechanistic roles of the ERK subfamily members in EMT and tumor progression in diverse biological systems.