The pathways to tumor suppression via route p38

Senescent cells promote breast cancer cells motility by secreting GM-CSF and bFGF that activate the JNK signaling pathway

BACKGROUND

Cellular senescence can be induced in mammalian tissues by multiple stimuli, including aging, oncogene activation and loss of tumor suppressor genes, and various types of stresses. While senescence is a tumor suppressing mechanism when induced within premalignant or malignant tumor cells, senescent cells can promote cancer development through increased secretion of growth factors, cytokines, chemokines, extracellular matrix, and degradative enzymes, collectively known as senescence-associated secretory phenotype (SASP). Previous studies indicated that senescent cells, through SASP factors, stimulate tumor cell invasion that is a critical step in cancer cell metastasis.

METHODS

In the current study, we investigated the effect of senescent cells on the motility of breast cancer cells, which is another key step in cancer cell metastasis. We analyzed the motility of breast cancer cells co-cultured with senescent cells in vitro and metastasis of the breast cancer cells co-injected with senescent cells in orthotopic xenograft models. We also delineated the signaling pathway mediating the effect of senescent cells on cancer cell motility.

RESULTS

Our results indicate that senescent cells stimulated the migration of breast cancer cells through secretion of GM-CSF and bFGF, which in turn induced activation of the JNK pathway in cancer cells. More importantly, senescent cells promoted breast cancer metastasis, with a minimum effect on the primary tumor growth, in orthotopic xenograft mouse models.

CONCLUSIONS

These results have revealed an additional mechanism by which senescent cells promote tumor cell metastasis and tumor progression, and will potentially lead to identification of novel targets for cancer therapies that suppress metastasis, the major cause of cancer mortality.

TG2 participates in pulmonary vascular remodelling by regulating the senescence of pulmonary artery smooth muscle cells

Pulmonary hypertension (PH) is a severe cardiovascular disease characterised by pulmonary vascular remodelling. The pivotal role of cellular senescence in vascular remodelling has been acknowledged. Transglutaminase type 2 (TG2), a calcium-dependent enzyme, is intricately linked to both cellular senescence and PH. However, the precise mechanisms underlying the involvement of TG2 in PH remain unclear. In this study, we explored the expression of TG2 and the cellular senescence marker p16INK4a in the pulmonary vasculature of mice with PH induced by hypoxia combined with SU5416. Our findings revealed upregulation of both TG2 and p16INK4a expression in the pulmonary vasculature of PH mice. Additionally, a notable increase in TG2 expression was observed in senescent pulmonary artery smooth muscle cells (PASMC). To delve deeper, we employed proteomic sequencing to reveal seven genes associated with cellular senescence, with a subsequent focus on MAPK14. Our investigation revealed that TG2 regulates senescence in PASMC by modulating the phosphorylation levels of MAPK14. Additionally, in the context of hypoxia combined with SU5416, our observations revealed a noteworthy reduction in both pulmonary vascular remodelling and senescent manifestations in smooth muscle-specific TG2 knockout mice compared with their wild-type counterparts. In summary, our findings indicate that TG2 deficiency lowers the senescence levels of PASMC by inhibiting the activity of MAPK14. This inhibition of senescence in the pulmonary vasculature of PH mice helps to decelerate the progression of pulmonary vascular remodelling and consequently hinders the onset and development of PH.

Anticancer Effects of Secoiridoids-A Scoping Review of the Molecular Mechanisms behind the Chemopreventive Effects of the Olive Tree Components Oleocanthal, Oleacein, and Oleuropein

The olive tree (Olea europaea) and olive oil hold significant cultural and historical importance in Europe. The health benefits associated with olive oil consumption have been well documented. This paper explores the mechanisms of the anti-cancer effects of olive oil and olive leaf, focusing on their key bioactive compounds, namely oleocanthal, oleacein, and oleuropein. The chemopreventive potential of oleocanthal, oleacein, and oleuropein is comprehensively examined through this systematic review. We conducted a systematic literature search to identify eligible articles from Scopus, PubMed, and Web of Science databases published up to 10 October 2023. Among 4037 identified articles, there were 88 eligible articles describing mechanisms of chemopreventive effects of oleocanthal, oleacein, and oleuropein. These compounds have the ability to inhibit cell proliferation, induce cell death (apoptosis, autophagy, and necrosis), inhibit angiogenesis, suppress tumor metastasis, and modulate cancer-associated signalling pathways. Additionally, oleocanthal and oleuropein were also reported to disrupt redox hemostasis. This review provides insights into the chemopreventive mechanisms of O. europaea-derived secoiridoids, shedding light on their role in chemoprevention. The bioactivities summarized in the paper support the epidemiological evidence demonstrating a negative correlation between olive oil consumption and cancer risk. Furthermore, the mapped and summarized secondary signalling pathways may provide information to elucidate new synergies with other chemopreventive agents to complement chemotherapies and develop novel nutrition-based anti-cancer approaches.

Xianglian Pill combined with 5-fluorouracil enhances antitumor activity and reduces gastrointestinal toxicity in gastric cancer by regulating the p38 MAPK/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Perioperative or postoperative adjuvant chemotherapy based on 5-fluorouracil (5-FU) is a common first-line adjuvant therapy for gastric cancer (GC). However, drug resistance and the side effects of 5-FU have reduced its efficacy. Among these side effects, gastrointestinal (GI) toxicity is one of the most common. Xianglian Pill (XLP) is a Chinese patent medicine that is commonly used for the treatment of diarrhoea. It can reduce inflammation and has a protective effect on the intestinal mucosa. Recent studies have shown that many components of XLP can inhibite tumor cell growth. However, the therapeutic effect of XLP in combination with 5-FU on GC is unclear.

AIM OF THE STUDY

To investigate whether the combination of XLP and 5-FU can enhance anti-GC activity while reducing GI toxicity.

MATERIALS AND METHODS

XLP was administered orally during intraperitoneal injection of 5-FU in GC mice model. Mice were continuously monitored for diarrhea and xenograft tumor growth. After 2 weeks, the mice were sacrificed and serum was collected to determine interleukin-6 levels. Pathological changes, the expression of pro-inflammatory factors and p38 mitogen-activated protein kinase (MAPK) in GI tissue were determined by Western blot analysis. Pathological changes, apoptosis levels and p38 MAPK expression levels in xenograft tissues were also determined.

RESULTS

The results showed that XLP could alleviate GI mucosal injury caused by 5-FU, alleviated diarrhea, and inhibited the expression of nuclear factor (NF)-κB and myeloid differentiation primary response-88. Besides, XLP could promote the 5-FU-induced apoptosis of GC cells and enhance the inhibitory effect of 5-FU on tumor xenografts. Further study showed that XLP administration could regulate the expression of p38 MAPK.

CONCLUSIONS

XLP in combination with 5-FU could alleviate its GI side effects and enhance its inhibitory effect on xenograft tumor. Moreover, these effects were found to be related to the regulation of the p38 MAPK/NF-κB pathway.

Crosstalk between lipid metabolism and EMT: emerging mechanisms and cancer therapy

Lipids are the key component of all membranes composed of a variety of molecules that transduce intracellular signaling and provide energy to the cells in the absence of nutrients. Alteration in lipid metabolism is a major factor for cancer heterogeneity and a newly identified cancer hallmark. Reprogramming of lipid metabolism affects the diverse cancer phenotypes, especially epithelial-mesenchymal transition (EMT). EMT activation is considered to be an essential step for tumor metastasis, which exhibits a crucial role in the biological processes including development, wound healing, and stem cell maintenance, and has been widely reported to contribute pathologically to cancer progression. Altered lipid metabolism triggers EMT and activates multiple EMT-associated oncogenic pathways. Although the role of lipid metabolism-induced EMT in tumorigenesis is an attractive field of research, there are still significant gaps in understanding the underlying mechanisms and the precise contributions of this interplay. Further study is needed to clarify the specific molecular mechanisms driving the crosstalk between lipid metabolism and EMT, as well as to determine the potential therapeutic implications. The increased dependency of tumor cells on lipid metabolism represents a novel therapeutic target, and targeting altered lipid metabolism holds promise as a strategy to suppress EMT and ultimately inhibit metastasis.

Natural bioactive compounds and FOXO3a in cancer therapeutics: An update

Forkhead box protein 3a (FOXO3a) is a transcription factor that regulates various downstream targets upon its activation, leading to the upregulation of tumor suppressor and apoptotic pathways. Hence, targeting FOXO3a is an emerging strategy for cancer prevention and treatment. Recently, Natural Bioactive Compounds (NBCs) have been used in drug discovery for treating various disorders including cancer. Notably, several NBCs have been shown as potent FOXO3a activators. NBCs upregulate FOXO3a expressions through PI3K/Akt, MEK/ERK, AMPK, and IκB signaling pathways. FOXO3a promotes its anticancer effects by upregulating the levels of its downstream targets, including Bim, FasL, and Bax, leading to apoptosis. This review focuses on the dysregulation of FOXO3a in carcinogenesis and explores the potent FOXO3a activating NBCs for cancer prevention and treatment. Additionally, the review evaluates the safety and efficacy of NBCs. Looking ahead, NBCs are anticipated to become a cost-effective, potent, and safer therapeutic option for cancer, making them a focal point of research in the field of cancer prevention and treatment.

Unraveling the mechanisms of intervertebral disc degeneration: an exploration of the p38 MAPK signaling pathway

Intervertebral disc (IVD) degeneration (IDD) is a worldwide spinal degenerative disease. Low back pain (LBP) is frequently caused by a variety of conditions brought on by IDD, including IVD herniation and spinal stenosis, etc. These conditions bring substantial physical and psychological pressure and economic burden to patients. IDD is closely tied with the structural or functional changes of the IVD tissue and can be caused by various complex factors like senescence, genetics, and trauma. The IVD dysfunction and structural changes can result from extracellular matrix (ECM) degradation, differentiation, inflammation, oxidative stress, mechanical stress, and senescence of IVD cells. At present, the treatment of IDD is basically to alleviate the symptoms, but not from the pathophysiological changes of IVD. Interestingly, the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway is involved in many processes of IDD, including inflammation, ECM degradation, apoptosis, senescence, proliferation, oxidative stress, and autophagy. These activities in degenerated IVD tissue are closely relevant to the development trend of IDD. Hence, the p38 MAPK signaling pathway may be a fitting curative target for IDD. In order to better understand the pathophysiological alterations of the intervertebral disc tissue during IDD and offer potential paths for targeted treatments for intervertebral disc degeneration, this article reviews the purpose of the p38 MAPK signaling pathway in IDD.

Isoform-specific optical activation of kinase function reveals p38-ERK signaling crosstalk

Evolution has diversified the mammalian proteome by the generation of protein isoforms that originate from identical genes, e.g., through alternative gene splicing or post-translational modifications, or very similar genes found in gene families. Protein isoforms can have either overlapping or unique functions and traditional chemical, biochemical, and genetic techniques are often limited in their ability to differentiate between isoforms due to their high similarity. This is particularly true in the context of highly dynamic cell signaling cascades, which often require acute spatiotemporal perturbation to assess mechanistic details. To that end, we describe a method for the selective perturbation of the individual protein isoforms of the mitogen-activated protein kinase (MAPK) p38. The genetic installation of a photocaging group at a conserved active site lysine enables the precise light-controlled initiation of kinase signaling, followed by investigation of downstream events. Through optical control, we have identified a novel point of crosstalk between two major signaling cascades: the p38/MAPK pathway and the extracellular signal-regulated kinase (ERK)/MAPK pathway. Specifically, using the photoactivated p38 isoforms, we have found the p38γ and p38δ variants to be positive regulators of the ERK signaling cascade, while confirming the p38α and p38β variants as negative regulators.

Copper metabolism and hepatocellular carcinoma: current insights

Copper is an essential trace element that acts as a cofactor in various enzyme active sites in the human body. It participates in numerous life activities, including lipid metabolism, energy metabolism, and neurotransmitter synthesis. The proposal of "Cuproptosis" has made copper metabolism-related pathways a research hotspot in the field of tumor therapy, which has attracted great attention. This review discusses the biological processes of copper uptake, transport, and storage in human cells. It highlights the mechanisms by which copper metabolism affects hepatocellular carcinogenesis and metastasis, including autophagy, apoptosis, vascular invasion, cuproptosis, and ferroptosis. Additionally, it summarizes the current clinical applications of copper metabolism-related drugs in antitumor therapy.

OPN up-regulated proliferation and invasion of head and neck squamous cell carcinoma through the p38MAPK signaling pathway

OBJECTIVE

Osteopontin (OPN) is aberrantly expressed in various tumors. However, its role and detailed mechanisms in head and neck squamous cell carcinoma (HNSCC) have not been extensively described.

STUDY DESIGN

Expression of OPN in HNSCC was examined at the gene and protein levels. The effect of cell proliferation ability was examined by Cell Counting Kit-8, colony formation assay, cell invasiveness by Transwell assay, the effect of OPN on protein expression of Capase-3 and Bcl2 by Western blotting, and the expression of p38MAPK signaling pathway by p38MAPK inhibitor SB203580.

RESULTS

We found that OPN expression was higher in human HNSCC tissues than in adjacent tissues. Osteopontin may regulate the proliferation and invasion of HNSCC cells through the p38-MAPK signaling pathway.

DISCUSSION

Our study identifies an important role for OPN in HNSCC and further demonstrates that it may regulate the proliferation and invasion of HNSCC cells by activating the p38-MAPK signaling pathway. Osteopontin may be a promising prognostic and diagnostic indicator and a potential target for cancer therapy.

Crosstalk between phytochemicals and inflammatory signaling pathways

Novel bioactive constituents from natural sources are actively being investigated. The phytochemicals in these phenolic compounds are believed to have a variety of beneficial effects on human health. Several phenolic compounds have been found in plants. The antioxidant potential of phenols has been discussed in numerous studies along with their anti-inflammatory effects on pro-inflammatory cytokine, inducible cyclooxygenase-2, and nitric oxide synthase. Through current study, an attempt is made to outline and highlight a wide variety of inflammation-associated signaling pathways that have been modified by several natural compounds. These signaling pathways include nuclear factor-kappa B (NF-кB), activator protein (AP)-1, protein tyrosine kinases (PTKs), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factors, tyrosine phosphatidylinositol 3-kinase (PI3K)/AKT, and the ubiquitin-proteasome system. In light of the influence of natural substances on signaling pathways, their impact on the production of inflammatory mediator is highlighted in this review.

FTO regulates the DNA damage response via effects on cell-cycle progression

The fat mass and obesity-associated protein FTO is an "eraser" of N6-methyladenosine, the most abundant mRNA modification. FTO plays important roles in tumorigenesis. However, its activities have not been fully elucidated and its possible involvement in DNA damage - the early driving event in tumorigenesis - remains poorly characterized. Here, we have investigated the role of FTO in the DNA damage response (DDR) and its underlying mechanisms. We demonstrate that FTO responds to various DNA damage stimuli. FTO is overexpressed in mice following exposure to the promutagens aristolochic acid I and benzo[a]pyrene. Knockout of the FTO gene in TK6 cells, via CRISPR/Cas9, increased genotoxicity induced by DNA damage stimuli (micronucleus and TK mutation assays). Cisplatin- and diepoxybutane-induced micronucleus frequencies and methyl methanesulfonate- and azathioprine-induced TK mutant frequencies were also higher in FTO KO cells. We investigated the potential roles of FTO in DDR. RNA sequencing and enrichment analysis revealed that FTO deletion disrupted the p38 MAPK pathway and inhibited the activation of nucleotide excision repair and cell-cycle-related pathways following cisplatin (DNA intrastrand cross-links) treatment. These effects were confirmed by western blotting and qRT-PCR. FTO deletion impaired cell-cycle arrest at the G2/M phase following cisplatin and diepoxybutane treatment (flow cytometry analysis). Our findings demonstrated that FTO is involved in several aspects of DDR, acting, at least in part, by impairing cell cycle progression.

Roles of p38 MAPK signalling in intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a common degenerative disease mediated by multiple factors. Because of its complex aetiology and pathology, no specific molecular mechanisms have yet been identified and no definitive treatments are currently available for IVDD. p38 mitogen-activated protein kinase (MAPK) signalling, part of the serine and threonine (Ser/Thr) protein kinases family, is associated with the progression of IVDD, by mediating the inflammatory response, increasing extracellular matrix (ECM) degradation, promoting cell apoptosis and senescence and suppressing cell proliferation and autophagy. Meanwhile, the inhibition of p38 MAPK signalling has a significant effect on IVDD treatment. In this review, we first summarize the regulation of p38 MAPK signalling and then highlight the changes in the expression of p38 MAPK signalling and their impact on pathological process of IVDD. Moreover, we discuss the current applications and future prospects of p38 MAPK as a therapeutic target for IVDD treatment.

P38 MAPK and Radiotherapy: Foes or Friends?

Over the last 30 years, the study of the cellular response to ionizing radiation (IR) has increased exponentially. Among the various signaling pathways affected by IR, p38 MAPK has been shown to be activated both in vitro and in vivo, with involvement in key processes triggered by IR-mediated genotoxic insult, such as the cell cycle, apoptosis or senescence. However, we do not yet have a definitive clue about the role of p38 MAPK in terms of radioresistance/sensitivity and its potential use to improve current radiotherapy. In this review, we summarize the current knowledge on this family of MAPKs in response to IR as well as in different aspects related to radiotherapy, such as their role in the control of REDOX, fibrosis, and in the radiosensitizing effect of several compounds.

E2F1 Affects the Therapeutic Response to Neoadjuvant Therapy in Breast Cancer

This study is aimed at screening genes for predicting the sensitivity response and favorable outcome of neoadjuvant therapy in breast cancer. We downloaded neoadjuvant therapy genetic data of breast cancer and separated it into the pathological complete response (pCR) group and the non-pCR group. Differential expression analysis was performed to select the differentially expressed genes (DEGs). After that, we investigated the enriched biological processes and pathways of DEGs. Then, core up/down protein-protein interaction (PPI) network was, respectively, constructed to identify the hub genes. A transcription factor-target gene regulation network was built to screen core transcription factors (TFs). We found one upregulated DEG (KLHDC7B) and four downregulated DEGs (TFF1, LOC440335, SLC39A6, and MLPH) overlapped in three datasets. All DEGs were mainly enriched in pathways related to DNA biosynthesis, cell cycle, immune response, metabolism, and angiogenesis. The hub genes were KRT18, IL7R, HIST1H1A, and E2F1. The core TFs were HOXA9, SPDEF, FOXA1, E2F1, and PGR. RT-qPCR suggested that E2F1 was overexpressed in MCF-7, but HOXA9 was low-expressed. Western blot suggested that the MAPK signal pathway was inhibited in MCF-7/ADR. That is to say, some genes and core TFs can predict the sensitivity response of neoadjuvant therapy in breast cancer. And E2F1 may be involved in the process of drug resistance by regulating the MAPK signaling pathway. These might be useful as sensitive genes for the efficacy evaluation of neoadjuvant chemotherapy in breast cancer.

Multi-stage virtual screening of natural products against p38α mitogen-activated protein kinase: predictive modeling by machine learning, docking study and molecular dynamics simulation

p38α is a mitogen-activated protein kinase (MAPK), and the signaling pathways involved are closely related to the inflammation, apoptosis and differentiation of cells, which also makes it an attractive target for drug discovery. With the high efficiency and low cost, virtual screening technology is becoming an indispensable part of drug development. In this study, a novel multi-stage virtual screening method based on machine learning, molecular docking and molecular dynamics simulation was developed to identify p38α MAPK inhibitors from natural products in ZINC database, which improves the prediction accuracy by considering and utilizing both ligand and receptor information compared to any individual approach. Ultimately, we screened out two candidate inhibitors with acceptable ADMET properties (ZINC4260400 and ZINC8300300). Among the generated machine learning models, Random Forest (RF) and Support Vector Machine (SVM) performed better, with the area under the receiver operating characteristic curve (AUC) values of 0.932 and 0.931 on the test set, as well as 0.834 and 0.850 on the external validation set. In addition, the results of molecular docking and ADMET prediction showed that two compounds with appropriate pharmacokinetic properties had binding free energies less than −8.0 kcal/mol for the target protein, and the results of molecular dynamics simulations further confirmed that they were stable during the process of inhibition.

Impact of Myeloid p38α/MAPK on Orthodontic Tooth Movement

Objectives: Myeloid p38α/MAPK regulate and coordinate osteoclastogenesis. The present study was conducted to investigate the role of myeloid p38α/MAPK during orthodontic tooth movement. Methods: Orthodontic tooth movement was performed in wildtype and p38α^Δmyel mice lacking p38α/MAPK expression in myeloid cells. First, bone parameter as well as osteoblast and osteoclast number were determined in tibiae. RNA was isolated from the untreated and orthodontically treated maxillary jaw side and expression of genes involved in inflammation and bone remodelling were analysed. Finally, periodontal bone loss, alveolar bone density and extent of orthodontic tooth movement were assessed. Results: Bone density was increased in p38α^Δmyel mice compared to wildtype mice in tibiae (p = 0.043) and alveolar bone (p = 0.003). This was accompanied by a reduced osteoclast number in tibiae (p = 0.005) and TRAP5b in serum (p = 0.015). Accordingly, expression of osteoclast-specific genes was reduced in p38α^Δmyel mice. Extent of tooth movement was reduced in p38α^Δmyel mice (p = 0.024). This may be due to the higher bone density of the p38αΔmyel mice. Conclusions: Myeloid p38α/MAPK thus appears to play a regulatory role during orthodontic tooth movement by regulating osteoclastogenesis.

Redox-sensitive signaling pathways in renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most lethal urological cancers, highly resistant to chemo and radiotherapy. Obesity and smoking are the best-known risk factors of RCC, both related to oxidative stress presence, suggesting a significant role in RCC development and maintenance. Surgical resection is the treatment of choice for localized RCC; however, this neoplasia is hardly diagnosable at its initial stages, occurring commonly in late phases and even when metastasis is already present. Systemic therapies are the option against RCC in these more advanced stages, such as cytokine therapy or a combination of tyrosine kinase inhibitors with immunotherapies; nevertheless, these strategies are still insufficient. A field poorly analyzed in this neoplasia is the status of cell signaling pathways sensible to the redox state, which have been associated with the development and maintenance of RCC. This review focuses on alterations reported in the following redox-sensitive molecules and signaling pathways in RCC: mitogen-activated protein kinases, protein kinase B (AKT)/tuberous sclerosis complex 2/mammalian target of rapamycin C1, AKT/glycogen synthase kinase 3/β-catenin, nuclear factor κB/inhibitor of κB/epidermal growth factor receptor, and protein kinase Cζ/cut-like homeodomain protein/factor inhibiting hypoxia-inducible factor (HIF)/HIF as potential targets for redox therapy.

The p38 MAPK Components and Modulators as Biomarkers and Molecular Targets in Cancer

The mitogen-activated protein kinase (MAPK) family is an important bridge in the transduction of extracellular and intracellular signals in different responses at the cellular level. Within this MAPK family, the p38 kinases can be found altered in various diseases, including cancer, where these kinases play a fundamental role, sometimes with antagonistic mechanisms of action, depending on several factors. In fact, this family has an immense number of functionalities, many of them yet to be discovered in terms of regulation and action in different types of cancer, being directly involved in the response to cancer therapies. To date, three main groups of MAPKs have been identified in mammals: the extracellular signal-regulated kinases (ERK), Jun N-terminal kinase (JNK), and the different isoforms of p38 (α, β, γ, δ). In this review, we highlight the mechanism of action of these kinases, taking into account their extensive regulation at the cellular level through various modifications and modulations, including a wide variety of microRNAs. We also analyze the importance of the different isoforms expressed in the different tissues and their possible role as biomarkers and molecular targets. In addition, we include the latest preclinical and clinical trials with different p38-related drugs that are ongoing with hopeful expectations in the present/future of developing precision medicine in cancer.

MAGP2 induces tumor progression by enhancing uPAR-mediated cell proliferation

Microfibril-associated glycoprotein 2 (MAGP2) plays an important role in regulating cell signaling and acts as a biomarker to predict the prognostic effect of tumor therapy. However, research on MAGP2 mostly focuses on its extracellular signal transmission features, and its potential intracellular function is rarely reported. Here, we reported that intracellular MAGP2 increased the stability of urokinase-type plasminogen activator receptor (uPAR) in the cell by direct interaction which inhibits the lysosomal-mediated degradation of uPAR. Furthermore, with the detection of protein content changes and proteomics analysis, we found that highly expressed MAGP2 promoted the proliferation of tumor cells through uPAR-mediated p38-NF-ĸB signaling axis activation, enhancement of DNA damage repair and reduction of cell stagnation in the S phase of the cell cycle. In the nude mouse xenograft model of colorectal cancer, the upregulation of MAGP2 in tumor cells significantly promoted tumor progression, while the downregulation of uPAR significantly attenuated tumor progression. These studies elucidate the role of MAGP2 inside the cell and provide a new explanation for why patients with higher MAGP2 expression in tumors are associated with a worse prognosis. In addition, we also determined a mechanism for the stable existence of uPAR in the cell, providing information for the development of tumor drugs targeting uPAR.

Mast1 mediates radiation-induced gastric injury via the P38 MAPK pathway

Radiation-induced gastric injury is a serious adverse effect and reduces the efficacy of radiotherapy treatment. However, the mechanisms underlying radiation-induced stomach injury remain unclear. Here, mouse stomach and gastric epithelial cells were irradiated with different doses of X-ray radiation. The results showed that radiation induced gastric injury in vivo and in vitro. Differentially expressed functional mRNAs in irradiation-induced gastric tissues were screened from the Gene Expression Omnibus (GEO) database. We found that the expression of microtubule-associated serine/threonine kinase 1 (Mast1) was downregulated in mouse gastric tissues and gastric epithelial cells after irradiation. Furthermore, functional assays showed that knockdown of Mast1 inhibited growth and promoted apoptosis in gastric epithelial cells, while overexpression of Mast1 protected gastric epithelial cells from radiation damage. Mechanistically, Mast1 negatively regulated radiation-induced injury in gastric epithelial cells by inhibiting the activation of P38. The apoptosis caused by knockdown of Mast1 in gastric epithelial cells could be partially reversed by the P38 inhibitor SB203580. Moreover, data from several gastric cancer cell lines and online databases revealed that Mast1 was not involved in the development of gastric cancer. Collectively, our findings demonstrated that Mast1 is essential for radiation-induced gastric injury, providing a promising prognostic and therapeutic target.

Tomatidine Suppresses the Destructive Behaviors of Fibroblast-Like Synoviocytes and Ameliorates Type II Collagen-Induced Arthritis in Rats

Fibroblast-like synoviocytes (FLSs) are the prominent non-immune cells in synovium and play a pivotal role in rheumatoid arthritis (RA) pathogenesis. Searching for natural compounds that may suppress the pathological phenotypes of FLSs is important for the development of RA treatment. Tomatidine (Td), a steroidal alkaloid derived from the solanaceae family, has been reported to have anti-inflammatory, anti-tumor and immunomodulatory effects. However, its effect on RA remains unknown. Here, we examined the inhibitory effect of Td on TNFα-induced arthritic FLSs, and subsequently investigated its therapeutic effect on collagen-induced arthritis (CIA) rats. Our results revealed that Td significantly inhibited TNFα-induced proliferation and migration of arthritic FLSs. In addition, we found that Td treatment could efficaciously ameliorate synovial inflammation and joint destruction of rats with CIA. Both in vitro and in vivo studies showed that Td significantly suppressed the production of pro-inflammatory cytokines including IL-1β, IL-6 and TNFα, and downregulated the expression of MMP-9 and RANKL. Further molecular mechanism studies revealed that the inhibitory effect of Td on RA might attribute to the decreased activations of MAPKs (ERK and JNK) and NF-κB. These findings provide evidence that Td has the potential to be developed into a complementary or alternative agent for RA therapy.

Targeted protein degradation: A promise for undruggable proteins

Protein homeostasis, or "proteostasis," is indispensable for a balanced, healthy environment within the cell. However, when natural proteostasis mechanisms are overwhelmed from excessive loads of dysregulated proteins, their accumulation can lead to disease initiation and progression. Recently, the induced degradation of such disease-causing proteins by heterobifunctional molecules, i.e., PROteolysis TArgeting Chimeras (PROTACs), is emerging as a potential therapeutic modality. In the 2 decades since the PROTAC concept was proposed, several additional Targeted Protein Degradation (TPD) strategies have also been explored to target previously undruggable proteins, such as transcription factors. In this review, we discuss the progress and evolution of the TPD field, the breadth of the proteins targeted by PROTACs and the biological effects of their degradation.

The Role of the Ubiquitin Proteasome System in Glioma: Analysis Emphasizing the Main Molecular Players and Therapeutic Strategies Identified in Glioblastoma Multiforme

Gliomas constitute the most frequent tumors of the brain. High-grade gliomas are characterized by a poor prognosis caused by a set of attributes making treatment difficult, such as heterogeneity and cell infiltration. Additionally, there is a subgroup of glioma cells with properties similar to those of stem cells responsible for tumor recurrence after treatment. Since proteasomal degradation regulates multiple cellular processes, any mutation causing disturbances in the function or expression of its elements can lead to various disorders such as cancer. Several studies have focused on protein degradation modulation as a mechanism of glioma control. The ubiquitin proteasome system is the main mechanism of cellular proteolysis that regulates different events, intervening in pathological processes with exacerbating or suppressive effects on diseases. This review analyzes the role of proteasomal degradation in gliomas, emphasizing the elements of this system that modulate different cellular mechanisms in tumors and discussing the potential of distinct compounds controlling brain tumorigenesis through the proteasomal pathway.

Junctional Adhesion Molecule-Like Protein Promotes Tumor Progression and Metastasis via p38 Signaling Pathway in Gastric Cancer

Junctional adhesion molecule-like protein (JAML), a newly discovered junctional adhesion molecule (JAM), mediates the adhesion and migration processes of various immune cells and endothelial/epithelial cells, ultimately regulating inflammation reaction. However, its role in tumors remains to be determined. The expression of JAML was examined in gastric cancer (GC) and peritumoral tissues from 63 patients. The relationship between JAML expression and clinical characteristics was also observed. In vitro, GC cell migration and proliferation were assessed by wound healing assay, transwell migration assay and EdU incorporation assay. Immunohistochemical staining results showed that JAML expression level was higher in GC tissues than in peritumoral tissues. High expression of JAML in cancer tissues was associated with worse cell differentiation, local lymph node involvement, deep infiltration, and advanced stage. In vitro, we found that JAML silencing inhibited GC cell migration and proliferation, while JAML overexpression promoted GC cell migration and proliferation, partially via p38 signaling. Taken together, our study revealed a critical role for JAML to promote GC cell migration and proliferation. JAML might be a novel diagnostic biomarker and therapeutic target for GC.

Ebp1 p48 promotes oncogenic properties in hepatocellular carcinoma through p38 MAPK/HIF1α activation and p53 downregulation

The ErbB3 binding protein 1 (Ebp1) has been reported in several cancers, in which it can act as either a pro-oncogenic regulator or a tumor suppressor. However, the biological function and molecular mechanism of Ebp1 p48 in hepatocellular carcinoma (HCC) remain unclear. Here, we report that the long isoform of Ebp1, p48, is highly expressed in HCC tissues compared with normal tissues. Ebp1 p48 expression was correlated with the tumor size in HCC patients. Silencing Ebp1 p48 by transduction with lentiviral shEbp1 dramatically reduced the proliferation rate, soft agar colony generation, and tumor formation in vivo. We further demonstrated that Ebp1 p48 knockdown resulted in decreased p38 phosphorylation, which subsequently reduced hypoxia-inducible factor 1α (HIF1α) expression. Moreover, Ebp1 p48 knockdown led to an upregulation of p53 expression through MDM2 downregulation. Taken together, these results suggest that the Ebp1/p38/HIF1α signaling pathway and the Ebp1-mediated downregulation of p53 are involved in hepatocarcinogenesis. Therefore, Ebp1 and its downstream signaling pathways may be promising therapeutic targets of HCC.

Comprehensive Review of Methodology to Detect Reactive Oxygen Species (ROS) in Mammalian Species and Establish Its Relationship with Antioxidants and Cancer

Evidence suggests that reactive oxygen species (ROS) mediate tissue homeostasis, cellular signaling, differentiation, and survival. ROS and antioxidants exert both beneficial and harmful effects on cancer. ROS at different concentrations exhibit different functions. This creates necessity to understand the relation between ROS, antioxidants, and cancer, and methods for detection of ROS. This review highlights various sources and types of ROS, their tumorigenic and tumor prevention effects; types of antioxidants, their tumorigenic and tumor prevention effects; and abnormal ROS detoxification in cancer; and methods to measure ROS. We conclude that improving genetic screening methods and bringing higher clarity in determination of enzymatic pathways and scale-up in cancer models profiling, using omics technology, would support in-depth understanding of antioxidant pathways and ROS complexities. Although numerous methods for ROS detection are developing very rapidly, yet further modifications are required to minimize the limitations associated with currently available methods.

A Crosstalk Between Dual-Specific Phosphatases and Dual-Specific Protein Kinases Can Be A Potential Therapeutic Target for Anti-cancer Therapy

While protein tyrosine kinases (PTKs) play an initiative role in growth factor-mediated cellular processes, protein tyrosine phosphatases (PTPs) negatively regulates these processes, acting as tumor suppressors. Besides selective tyrosine dephosphorylation of PTKs via PTPs may affect oncogenic pathways during carcinogenesis. The PTP family contains a group of dual-specificity phosphatases (DUSPs) that regulate the activity of Mitogen-activated protein kinases (MAPKs), which are key effectors in the control of cell growth, proliferation and survival. Abnormal MAPK signaling is critical for initiation and progression stages of carcinogenesis. Since depletion of DUSP-MAPK phosphatases (MKPs) can reduce tumorigenicity, altering MAPK signaling by DUSP-MKP inhibitors could be a novel strategy in anti-cancer therapy. Moreover, Cdc25A is, a DUSP and a key regulator of the cell cycle, promotes cell cycle progression by dephosphorylating and activating cyclin-dependent kinases (CDK). Cdc25A-CDK pathway is a novel mechanism in carcinogenesis. Besides the mammalian target of rapamycin (mTOR) kinase inhibitors or mammalian target of rapamycin complex 1 (mTORC1) inhibition in combination with the dual phosphatidylinositol 3 kinase (PI3K)/mTOR or AKT kinase inhibitors are more effective in inhibiting the phosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and cap-dependent translation. Dual targeting of the Akt and mTOR signaling pathways regulates cellular growth, proliferation and survival. Like the Cdc2-like kinases (CLK), dual-specific tyrosine phosphorylation-regulated kinases (DYRKs) are essential for the regulation of cell fate. The crosstalk between dual-specific phosphatases and dual- specific protein kinases is a novel drug target for anti-cancer therapy. Therefore, the focus of this chapter involves protein kinase modules, critical biochemical checkpoints of cancer therapy and the synergistic effects of protein kinases and anti-cancer molecules.

CDK4/6 and MAPK-Crosstalk as Opportunity for Cancer Treatment

Despite the development of targeted therapies and novel inhibitors, cancer remains an undefeated disease. Resistance mechanisms arise quickly and alternative treatment options are urgently required, which may be partially met by drug combinations. Protein kinases as signaling switchboards are frequently deregulated in cancer and signify vulnerable nodes and potential therapeutic targets. We here focus on the cell cycle kinase CDK6 and on the MAPK pathway and on their interplay. We also provide an overview on clinical studies examining the effects of combinational treatments currently explored for several cancer types.

The anti-cancer effects and mechanisms of lactic acid bacteria exopolysaccharides in vitro: A review

Probiotic lactic acid bacteria (LAB) are a particular group of gram-positive bacteria that are usually involved in natural ferments and widely used in food manufacture industry. Most of them can produce exopolysaccharides (EPS), surface carbohydrate polymers with diverse biological functions. LAB EPS are potentially complementary and alternative medicines against cancer. EPS show anti-proliferative effects on a variety of tumor cells from intestine, liver, breast, etc. They modulate the development of tumors through various mechanisms including promoting apoptosis, inducing cell cycle arrest as well as anti-mutagenic, anti-oxidative, anti-angiogenesis and anti-inflammatory effects. Bacterial origin, existence form, chemical structure, purity et al. are important factors affecting the anticancer effects of EPS. The future challenge lies in elucidating the precise structure-function relationship of LAB EPS. Besides, more in vivo studies and further clinical trials are indispensable to confirm the anticancer effects.

NRASQ61K melanoma tumor formation is reduced by p38-MAPK14 activation in zebrafish models and NRAS-mutated human melanoma cells

Oncogenic BRAF and NRAS mutations drive human melanoma initiation. We used transgenic zebrafish to model NRAS-mutant melanoma, and the rapid tumor onset allowed us to study candidate tumor suppressors. We identified P38α-MAPK14 as a potential tumor suppressor in The Cancer Genome Atlas melanoma cohort of NRAS-mutant melanomas, and overexpression significantly increased the time to tumor onset in transgenic zebrafish with NRAS-driven melanoma. Pharmacological activation of P38α-MAPK14 using anisomycin reduced in vitro viability of melanoma cultures, which we confirmed by stable overexpression of p38α. We observed that the viability of MEK inhibitor resistant melanoma cells could be reduced by combined treatment of anisomycin and MEK inhibition. Our study demonstrates that activating the p38α-MAPK14 pathway in the presence of oncogenic NRAS abrogates melanoma in vitro and in vivo. SIGNIFICANCE: The significance of our study is in the accountability of NRAS mutations in melanoma. We demonstrate here that activation of p38α-MAPK14 pathway can abrogate NRAS-mutant melanoma which is contrary to the previously published role of p38α-MAPK14 pathway in BRAF mutant melanoma. These results implicate that BRAF and NRAS-mutant melanoma may not be identical biologically. We also demonstrate the translational benefit of our study by using a small molecule compound-anisomycin (already in use for other diseases in clinical trials) to activate p38α-MAPK14 pathway.

Synergistic Interactions of 5-Fluorouracil with Inhibitors of Protein Kinase CK2 Correlate with p38 MAPK Activation and FAK Inhibition in the Triple-Negative Breast Cancer Cell Line

Background: The combination effect of 5-fluorouracil (5-FU) with either CX-4945 or a new inhibitor of protein kinase CK2, namely 14B (4,5,6,7-tetrabromo-1-(3-bromopropyl)-2-methyl-1H-benzimidazole), on the viability of MCF-7 and triple-negative MDA-MB-231 breast cancer cell lines was studied. Methods: Combination index (CI) values were determined using an MTT-based assay and the Chou-Talalay model. The effect of the tested drug combinations on pro-apoptotic properties and cell cycle progression was examined using flow cytometry. The activation of FAK, p38 MAPK, and ERK1/2 kinases and the expression of selected pro-apoptotic markers in MDA-MB-231 cell line after the combined treatment were evaluated by the western blot method. Confocal microscopy was used to examine actin network in MDA-MB-231. Results: Our results showed that a synergistic effect (CI < 1) occurred in MDA-MB-231 after treatment with both combinations of 5-FU with 14B or CX-4945, whereas the combination of 5-FU and 14B evoked an antagonistic effect in MCF-7. We conclude that the synergistic interactions (CI < 1) observed for both the combinations of 5-FU and 14B or CX-4945 in MDA-MB-231 correlated with an activation of p38 MAPK, inhibition of FAK, increased expression of apoptogenic markers, prolongation of S-phase of cell cycle, and destabilization of actin network. Conclusions: The obtained results support the recent observation that CK2 inhibitors can improve 5-FU-based anticancer therapy and FAK kinase can be an attractive molecular target in breast cancer therapy.

Her2 promotes early dissemination of breast cancer by suppressing the p38-MK2-Hsp27 pathway that is targetable by Wip1 inhibition

Cancer can metastasize from early lesions without detectable tumors. Despite extensive studies on metastasis in cancer cells from patients with detectable primary tumors, mechanisms for early metastatic dissemination are poorly understood. Her2 promotes breast cancer early dissemination by inhibiting p38, but the downstream pathway in this process was unknown. Using early lesion breast cancer models, we demonstrate that the effect of p38 suppression by Her2 on early dissemination is mediated by MK2 and Hsp27. The early disseminating cells in the MMTV-Her2 breast cancer model are Her2^highp-p38^lowp-MK2^lowp-Hsp27^low, which also exist in human breast carcinoma tissues. Suppression of p38 and MK2 by Her2 reduces MK2-mediated Hsp27 phosphorylation, and unphosphorylated Hsp27 binds to β-catenin and enhances its phosphorylation by Src, leading to β-catenin activation and disseminating phenotypes in early lesion breast cancer cells. Pharmacological inhibition of MK2 promotes, while inhibition of a p38 phosphatase Wip1 suppresses, early dissemination in vivo. These findings identify Her2-mediated suppression of the p38-MK2-Hsp27 pathway as a novel mechanism for cancer early dissemination, and provide a basis for new therapies targeting early metastatic dissemination in Her2⁺ breast cancer.

An overview of mammalian p38 mitogen-activated protein kinases, central regulators of cell stress and receptor signaling

The p38 family is a highly evolutionarily conserved group of mitogen-activated protein kinases (MAPKs) that is involved in and helps co-ordinate cellular responses to nearly all stressful stimuli. This review provides a succinct summary of multiple aspects of the biology, role, and substrates of the mammalian family of p38 kinases. Since p38 activity is implicated in inflammatory and other diseases, we also discuss the clinical implications and pharmaceutical approaches to inhibit p38.

Pazopanib and Trametinib as a Synergistic Strategy against Osteosarcoma: Preclinical Activity and Molecular Insights

Receptor tyrosine kinases (RTKs) inhibitors’ activity in advanced osteosarcoma is significant but short-lived. To prevent or at least delay drug resistance, we explored a vertical inhibition by combining drugs acting at different levels of the RTK pathways (pazopanib + trametinib). We studied pazopanib + trametinib antitumor activity both in vitro and in vivo (MNNG-HOS and KHOS xenografts in NOD/SCID mice) investigating the molecular mechanisms and potential escapes. The involvement of MAPK-PI3K pathways was validated by Nanostring technology, western blot and by silencing/overexpression experiments. Pazopanib targets were expressed on seven osteosarcoma cell lines and their pathways were activated. Pazopanib + trametinib exhibited synergistic antitumor activity by inducing apoptosis and inhibiting ERK1/2 and Akt. In vivo antitumor activity was shown in osteosarcoma-bearing mice. The drug combination significantly down-modulated RTK Ephrin Type-A Receptor 2 (EphA2) and Interleukin-7 Receptor (IL-7R), whereas induced mitogen-activated protein-kinase kinase (MAPKK) MEK6. EphA2 silencing significantly reduced osteosarcoma cell proliferation and migration, while impeding MEK6 up-regulation in the treated cells significantly increased the antitumor effect of the studied drugs. Moreover, the up-regulation of MEK6 reduced combination activity. Pazopanib + trametinib demonstrated synergistic antitumor effects in osteosarcoma models through ERK and Akt inhibition and EphA2 and IL-7R down-modulation. MEK6 up-regulation might evoke escaping mechanism.

ROS and oncogenesis with special reference to EMT and stemness

Elevation of the level of intracellular reactive oxygen species (ROS) has immense implication in the biological system. On the one hand, ROS promote the signaling cascades for the maintenance of normal physiological functions, the phenomenon referred to as redox biology, and on the other hand increased ROS can cause damages to the cellular macromolecules as well as genetic material, the process known as oxidative stress. Oxidative stress acts as an etiological factor for wide varieties of pathologies, cancer being one of them. ROS is regarded as a "double-edged sword" with respect to oncogenesis. It can suppress as well as promote the malignant progression depending on the type of signaling pathway it uses. Moreover, the attribution of ROS in promoting phenotypic plasticity as well as acquisition of stemness during neoplasia has become a wide area of research. The current review discussed all the aspects of ROS in the perspective of tumor biology with special reference to epithelial-mesenchymal transition (EMT) and cancer stem cells.

Origanum majorana Essential Oil Triggers p38 MAPK-Mediated Protective Autophagy, Apoptosis, and Caspase-Dependent Cleavage of P70S6K in Colorectal Cancer Cells

Colorectal cancer (CRC) is the third most common type of cancer in terms of incidence and mortality worldwide. Here we have investigated the anti-colon cancer potential of Origanum majorana essential oil (OMEO) and its underlying mechanisms of action. We showed that OMEO significantly inhibited the cellular viability and colony growth of human HT-29 colorectal cancer cells. OMEO induced protective autophagy, associated with downregulation of the mTOR/p70S6K pathway, and activated caspase-8 and caspase-9-dependent apoptosis. Blockade of autophagy with 3-methyladenine (3-MA) and chloroquine (CQ), two autophagy inhibitors, potentiated the OMEO-induced apoptotic cell death. Inversely, inhibition of apoptosis with the pan-caspase inhibitor, Z-VAD-FMK, significantly reduced cell death, suggesting that apoptosis represents the main mechanism of OMEO-induced cell death. Mechanistically, we found that OMEO induces protective autophagy and apoptotic cells death via the activation of the p38 MAPK signaling pathway. Pharmacological inhibition of p38 MAPK by the p38 inhibitors SB 202190 and SB 203580 not only significantly decreased apoptotic cell death, but also reduced the autophagy level in OMEO treated HT-29 cells. Strikingly, we found that OMEO also induces p38 MAPK-mediated caspase-dependent cleavage of p70S6K, a protein reported to be overexpressed in colon cancer and associated with drug resistance. Our findings suggest that OMEO inhibits colon cancer through p38 MAPK-mediated protective autophagy and apoptosis associated with caspase-dependent cleavage of p70S6K. To the best of our knowledge, this study is the first to report on the implications of the p38 MAPK signaling pathway in targeting p70S6K to caspase cleavage.

Mitogen-Activated Protein Kinase (MAPK) and Obesity-Related Cancer

Obesity is a major public health concern worldwide. The increased risk of certain types of cancer is now an established deleterious consequence of obesity, although the molecular mechanisms of this are not completely understood. In this review, we aim to explore the links between MAPK signalling and obesity-related cancer. We focus mostly on p38 and JNK MAPK, as the role of ERK remains unclear. These links are seen through the implication of MAPK in obesity-related immune paralysis as well as through effects on the endoplasmic reticulum stress response and activation of aromatase. By way of example, we highlight areas of interest and possibilities for future research in endometrioid endometrial cancer and hepatocellular carcinoma associated with non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and MAPK.

Single nucleotide polymorphisms associated with susceptibility for development of colorectal cancer: Case-control study in a Basque population

Given the significant population diversity in genetic variation, we aimed to investigate whether single nucleotide polymorphisms (SNPs) previously identified in studies of colorectal cancer (CRC) susceptibility were also relevant to the population of the Basque Country (North of Spain). We genotyped 230 CRC cases and 230 healthy controls for 48 previously reported CRC-susceptibility SNPs. Only the rs6687758 in DUPS10 exhibited a statistically significant association with CRC risk based on the crude analysis. The rs6687758 AG genotype conferred about 2.13-fold increased risk for CRC compared to the AA genotype. Moreover, we found significant associations in cases between smoking status, physical activity, and the rs6687758 SNP. The results of a Genetic Risk Score (GRS) showed that the risk alleles were more frequent in cases than controls and the score was associated with CRC in crude analysis. In conclusion, we have confirmed a CRC susceptibility locus and the existence of associations between modifiable factors and the rs6687758 SNP; moreover, the GRS was associated with CRC. However, further experimental validations are needed to establish the role of this SNP, the function of the gene identified, as well as the contribution of the interaction between environmental factors and this locusto the risk of CRC.

Lipoxin A4 attenuates hyperoxia‑induced lung epithelial cell injury via the upregulation of heme oxygenase‑1 and inhibition of proinflammatory cytokines

The present study examined whether lipoxin A4 (LXA4) increases the expression of HO‑1, and inhibits the production of interleukin 6 (IL‑6) and monocyte chemotactic protein 1 (MCP‑1) in LXA4‑induced protection during hyperoxia‑induced injury in murine lung epithelial cells (MLE‑12) and what signal pathway may participate in the actions of LXA4 inhibiting IL‑6 and MCP‑1. MLE‑12 cells were exposed to air or hyperoxia with or without pretreatment with LXA4, Zinc protoporphyrin IX (ZnPP‑IX), IL‑6, anti‑IL‑6, MCP‑1, anti‑MCP‑1, inhibitors of p38 mitogen‑activated protein kinase (p38 MAPK), protein kinase B (Akt) and extracellular signal‑regulated kinase 1/2 (ERK1/2) signaling pathways. The cell survival rates, cell viability, apoptosis rates, expression of superoxide dismutase (SOD), heme oxygenase‑1 (HO‑1), IL‑6 and MCP‑1, and the activations of p38 MAPK, ERK1/2 and Akt were measured. LXA4 significantly increased the cell survival rates, cell viability, SOD levels and HO‑1 expression, reduced the apoptosis rates, and inhibited the MCP‑1 and IL‑6 levels induced by hyperoxia in cells. ZnPP‑IX, an inhibitor of HO‑1, blocked LXA4‑induced protection on cell viability in cells exposed to hyperoxia. Anti‑IL‑6 and anti‑MCP‑1 improved the cell viability of cells exposed to hyperoxia. Inhibition of p38 MAPK and ERK1/2 blocked the expression of MCP‑1 and IL‑6 induced by hyperoxia. LXA4 inhibited the activation of p38 MAPK and ERK1/2 induced by hyperoxia, and increased the activation of the Akt signaling pathway, which was inhibited by hyperoxia. Therefore, LXA4 attenuated hyperoxia‑induced injury in MLE‑12 cells via the upregulation of HO‑1 expression. The protection of LXA4 in hyperoxia‑induced cell injury may be associated with the downregulation IL‑6 and MCP‑1 levels via the inhibition of the p38 MAPK and ERK1/2 signaling pathways.

Mutual Stabilization between TRIM9 Short Isoform and MKK6 Potentiates p38 Signaling to Synergistically Suppress Glioblastoma Progression

p38 signaling is broadly involved in controlling inflammation and stress-induced cell death; however, the mechanisms controlling its activity have seldom been studied. Here, we report that TRIM9 short isoform (TRIM9s) potentiates p38 signaling by stabilizing MKK6. Mechanistic studies revealed that TRIM9s promotes the K63-linked ubiquitination of MKK6 at Lys82, thus inhibiting the degradative K48-linked ubiquitination of MKK6 at the same lysine. MKK6 could also stabilize TRIM9s by promoting the phosphorylation of TRIM9s at Ser76/80 via p38, thereby blocking the ubiquitin-proteasome pathway. Further functional analyses showed that p38 signaling plays a critical role in suppressing glioblastoma progression. Co-reduction of MKK6 and TRIM9s is significantly associated with overall poor survival of glioblastoma patients. We identify a positive feedback loop in p38 signaling generated by MKK6-TRIM9s, which suppresses glioblastoma progression, and we provide insights into the mechanisms by which TRIM9s and MKK6 potentiate p38 signaling through mutual stabilization.

Fas signaling-mediated TH9 cell differentiation favors bowel inflammation and antitumor functions

Fas induces apoptosis in activated T cell to maintain immune homeostasis, but the effects of non-apoptotic Fas signaling on T cells remain unclear. Here we show that Fas promotes T_H9 cell differentiation by activating NF-κB via Ca²⁺-dependent PKC-β activation. In addition, PKC-β also phosphorylates p38 to inactivate NFAT1 and reduce NFAT1-NF-κB synergy to promote the Fas^-induced T_H9 transcription program. Fas ligation exacerbates inflammatory bowel disease by increasing T_H9 cell differentiation, and promotes antitumor activity in p38 inhibitor-treated T_H9 cells. Furthermore, low-dose p38 inhibitor suppresses tumor growth without inducing systemic adverse effects. In patients with tumor, relatively high T_H9 cell numbers are associated with good prognosis. Our study thus implicates Fas in CD4⁺ T cells as a target for inflammatory bowel disease therapy. Furthermore, simultaneous Fas ligation and low-dose p38 inhibition may be an effective approach for T_H9 cell induction and cancer therapy.

Fas signalling induces apoptosis of activated T cells to maintain immune homeostasis. Here the authors show that Fas also induces PKC-β activation to promote NF-κB-mediated T_H9 cell differentiation, while p38 activation by PKC-β antagonizes this effect, thereby supporting a synergy between p38 inhibitor and Fas for T_H9 differentiation.

Identification of NPAC as a novel biomarker and regulator for hepatocellular carcinoma

OBJECTIVE

Hepatocellular carcinoma (HCC) has a high morbidity and mortality around the world, yet the effective therapeutic option for HCC is still limited. NPAC, also known as glyoxylate reductase 1 homolog, is a new nuclear protein recently implicated in tumor biology. However, the role of NPAC in HCC remains unclear. The present study aimed to evaluate the clinical significance and potential role of NPAC in HCC.

METHODS

The NPAC expression in HCC tissues and matched adjacent normal tissues was detected by real-time polymerase chain reaction, immunohistochemistry (IHC), and Western blot analysis. The clinical significance of the expression of NPAC in HCC was assessed by the Kaplan-Meier survival curve and the Cox regression model. In addition, we established a doxiline-induced overexpression of the NPAC system. The effects of NPAC on HCC cell proliferation, migration, and apoptosis were checked by CCK-8 proliferation assays, transwell, and flow cytometry, respectively.

RESULTS

The NPAC expression was significantly downregulated in HCC tissues and HCC cell lines. NPAC reduction was significantly correlated with poorer survival among patients with HCC, and the multivariate analysis confirmed its independent prognostic value. Furthermore, overexpression of NPAC dramatically suppressed the proliferation of HCC cells and promoted HCC cells apoptosis. Besides, the levels of phosphorylation of janus kinase 2 (JAK2) and signal transduction and activator 3 (STAT3) were significantly reduced after overexpression of NPAC in HCC cell lines.

CONCLUSIONS

These results suggest that NPAC may play an important role in the development and progression of HCC, and can act as a novel potential prognostic biomarker and therapeutic target for HCC.

Approaches towards Longevity: Reprogramming, Senolysis, and Improved Mitotic Competence as Anti-Aging Therapies

Mainstream approaches that are currently used as anti-aging therapies primarily explore the senescence and epigenetic drift aging hallmarks and they are at two ends of the spectrum. While senolytic therapies include either the selective elimination of senescent cells or the disruption of their secretome with the use of drugs or natural compounds, cellular reprogramming uses genetic manipulation to revert cells all the way back to pluripotency. Here, we describe the progress that has been made on these therapies, while highlighting the major challenges involved. Moreover, based on recent findings elucidating the impact of mitotic shutdown and aneuploidy in cellular senescence, we discuss the modulation of mitotic competence as an alternative strategy to delay the hallmarks of aging. We propose that a regulated rise in mitotic competence of cells could circumvent certain limitations that are present in the senolytic and reprogramming approaches, by acting to decelerate senescence and possibly restore the epigenetic landscape.

Cellular senescence in dental pulp stem cells

OBJECTIVE

This short review summarizes our current knowledge about dental stem cell aging and about possible targets for the regulation of cellular senescence.

DESIGN

A literature search was performed using a combination of keywords, e.g., stem cells, replicative senescence, differentiation potential, dental pulp, dental follicle and periodontal ligament.

RESULTS

Previous studies have shown that cellular senescence occurs while the proliferation of dental stem cells. Moreover, the differentiation potential was significantly decreased in senescent stem cells and senescent cells secrete also factors that are harmful to the adjacent tissue cells. Moreover, many targets for the regulation of cellular senescence are considered; for example pathways related to the nutrient sensing such as the 5' adenosine monophosphate-activated protein kinase (AMPK) pathway.

CONCLUSIONS

The regulation of cellular senescence will play a crucial role in the clinical use of stem cells. However, there is no cell culture protocol available that prevents dental stem cell senescence. Therefore, more knowledge about molecular processes in stem cells is needed before and after the induction of senescence.

Acetyl-macrocalin B suppresses tumor growth in esophageal squamous cell carcinoma and exhibits synergistic anti-cancer effects with the Chk1/2 inhibitor AZD7762

Natural products derived from herbal medicines have become a major focus of anti-cancer drug discovery studies. Acetyl-macrocalin B (A-macB) is an ent-diterpenoid isolated from Isodon silvatica. This study aimed to examine the effect and molecular action of A-macB in esophageal squamous cell carcinoma (ESCC) and explore possible drug synergistic modalities. A-macB induced cellular reactive oxygen species (ROS) generation, initiated the p38 mitogen-activated protein kinase (MAPK) signaling pathway, and triggered the caspase-9-dependent apoptosis cascade in ESCC cells. The ROS scavenger N-acetylcysteine (NAC) and the specific p38 inhibitor SB203580 reversed the effects of A-macB on the p38 network and thus rescued ESCC cells from apoptosis. The cellular ROS increase was at least partially due to the suppression of glutathione-S-transferase P1 (GSTP1) by A-macB. A-macB also upregulated the Chk1/Chk2-Cdc25C/Cdc2/Cyclin B1 axis to induce G2/M phase arrest. The cell growth inhibition induced by A-macB was further enhanced by AZD7762, a specific Chk1/Chk2 inhibitor, with a combination index (CI) of <1. Moreover, A-macB efficiently suppressed xenograft growth without inducing significant toxicity, and AZD7762 potentiated the effects of A-macB in the suppression of tumor growth in vivo. Taken together, A-macB is a promising lead compound for ESCC and exerts synergistic anti-cancer effects with AZD7762.

Correlation of P38 Mitogen-Activated Protein Kinase Expression to Clinical Stage in Nasopharyngeal Carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is uncommon and usually diagnosed at the advanced stage. A subfamily of mitogen-activated protein kinase which is called p38 mitogen-activated protein kinase (MAPK) involved in response to stress, and plays an important role in cell regulation. There is a suggestion that p38 mitogen-activated protein kinase could be a potential biomarker to determine the clinical stage of nasopharyngeal carcinoma.

AIM

The aim of this study is for observing and analysing the correlation of p38 mitogen-activated protein kinase expression in regards to nasopharyngeal carcinoma patient's clinical stage.

METHODS

This study involved 126 nasopharyngeal carcinoma patients admitted to Haji Adam Malik General Hospital.

RESULTS

The result of this study indicates that nasopharyngeal carcinoma mostly found in the age group 41-60 years, male, non-keratinizing squamous cell carcinoma, and stage IV group. In immunohistochemistry evaluation, most of p38 mitogen-activated protein kinase overexpressed in non-keratinizing squamous cell carcinoma, T3-T4, N2-N3 and clinical stage III-IV. Spearman's test for categorical correlation yield p-value of < 0.001.

CONCLUSION

In conclusion, there is a significant correlation between p38 mitogen-activated protein kinase expression and the clinical stage of nasopharyngeal carcinoma.

Co-expression of nuclear P38 and hormone receptors is prognostic of good long-term clinical outcome in primary breast cancer and is linked to upregulation of DNA repair

Background

P38 mitogen activated protein kinase is an intermediary signal transduction factor with context-specific roles in breast cancer. Recent mechanistic studies add to the growing consensus that P38 is a tumour suppressor, and it may represent a novel target for breast cancer treatment. The aim of this study is to add definitive data on the prognostic value of P38 and its link with biomarkers in primary breast cancer.

Methods

A large, well-characterised series of 1332 primary breast cancer patients with long-term clinical follow-up was assessed for P38 expression by immunohistochemistry. Association of clinicopathological factors and a panel of breast cancer biomarkers was determined by chi-squared test, and multivariate survival analysis was performed using Cox Proportional Hazards regression modelling.

Results

This study shows that nuclear P38 is co-expressed with nuclear hormone receptors (p < 0.001) and is an independent prognostic marker of good long-term clinical outcome in primary breast cancer (hazard ratio 0.796, 95% confidence interval 0.662–0.957, p = 0.015). Significant association was found between expression of P38 and markers of DNA repair including nuclear BRCA1 and RAD51, and cleaved PARP1 (all p < 0.001).

Conclusions

The findings support the proposed role for P38 as a tumour suppressor in breast cancer via upregulation of DNA repair proteins and provide novel hypothesis-generating information on the potential role of P38 in adjuvant therapy decision making.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4924-2) contains supplementary material, which is available to authorized users.

Combined inhibition of MEK and PI3K pathways overcomes acquired resistance to EGFR-TKIs in non-small cell lung cancer

Compensatory activation of the signal transduction pathways is one of the major obstacles for the targeted therapy of non-small cell lung cancer (NSCLC). Herein, we present the therapeutic strategy of combined targeted therapy against the MEK and phosphoinositide-3 kinase (PI3K) pathways for acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in NSCLC. We investigated the efficacy of combined trametinib plus taselisib therapy using experimentally established EGFR-TKI-resistant NSCLC cell lines. The results showed that the feedback loop between MEK/ERK and PI3K/AKT pathways had developed in several resistant cell lines, which caused the resistance to single-agent treatment with either inhibitor alone. Meanwhile, the combined therapy successfully regulated the compensatory activation of the key intracellular signals and synergistically inhibited the cell growth of those cells in vitro and in vivo. The resistance mechanisms for which the dual kinase inhibitor therapy proved effective included (MET) mesenchymal-epithelial transition factor amplification, induction of epithelial-to-mesenchymal transition (EMT) and EGFR T790M mutation. In further analysis, the combination therapy induced the phosphorylation of p38 MAPK signaling, leading to the activation of apoptosis cascade. Additionally, long-term treatment with the combination therapy induced the conversion from EMT to mesenchymal-to-epithelial transition in the resistant cell line harboring EMT features, restoring the sensitivity to EGFR-TKI. In conclusion, our results indicate that the combined therapy using MEK and PI3K inhibitors is a potent therapeutic strategy for NSCLC with the acquired resistance to EGFR-TKIs.