Signal-regulated Protein Kinase Pathway Research Articles

Schistosoma mansoni excretory-secretory products induce protein kinase signalling, hyperkinesia, and stem cell proliferation in the opposite sex

Adult male and female schistosomes in copula dwell within human blood vessels and lay eggs that cause the major Neglected Tropical Disease human schistosomiasis. How males and females communicate to each other is poorly understood; however, male-female physical interaction is known to be important. Here, we investigate whether excretory-secretory products (ESPs), released into the external milieu by mature Schistosoma mansoni, might induce responses in the opposite sex. We demonstrate that ESPs adhere to the surface of opposite sex worms inducing the activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK) pathways, particularly in the parasite tegument. Furthermore, we show that mature worms stimulated signalling in juvenile worms. Strikingly, we demonstrate that ESPs from the opposite sex promote stem cell proliferation, in an ERK- and p38 MAPK-dependent manner, in the tegument and within the testes of males, and the ovaries and vitellaria of females. Hyperkinesia also occurs following opposite sex ESP exposure. Our findings support the hypothesis that male and female schistosomes may communicate over distance to modulate key processes underlying worm development and disease progression, opening unique avenues for schistosomiasis control.

RFC5, regulated by circ_0038985/miR‐3614‐5p, functions as an oncogene in the progression of colorectal cancer

Replication factor C 5 (RFC5) is involved in a variety of biological functions of cancer. However, the expression pattern of RFC5 and the underlying mechanisms in colorectal cancer (CRC) remain elusive. Here, we show that RFC5 is significantly upregulated in CRC tissues and cells. Patients with CRC and increased RFC5 levels have an unfavorable prognosis. RFC5 can promote the proliferation, migration, and invasion of CRC cells and inhibit the apoptosis of CRC cells. Additionally, upstream of RFC5, we constructed the competing endogenous RNA network and confirmed that RFC5 in this network was inhibited by miR-3614-5p by directly targeting its 3'-untranslated regions. We verified that circ_0038985, which is positively correlated with RFC5, directly targeted miR-3614-5p. Overexpression of circ_0038985 promoted CRC cell migration and invasion, and these effects were partially reversed by the reintroduction of miR-3614-5p. Moreover, we found that RFC5 may promote the vascular endothelial growth factor A (VEGFa)/vascular endothelial growth factor receptor 2 (VEGFR2)/extracellular signal-regulated protein kinase (ERK) pathway. The knockdown of RFC5 reduced CRC tumorigenesis in vivo. Collectively, these data demonstrate that the circ_0038985/miR-3614-5p/RFC5 axis plays a critical role in the progression of CRC, and RFC5 may promote CRC progression by affecting the VEGFa/VEGFR2/ERK pathway.

Human Placental Mesenchymal Stem Cells Relieve Primary Sclerosing Cholangitis via Upregulation of TGR5 in Mdr2-/- Mice and Human Intrahepatic Cholangiocyte Organoid Models.

Primary sclerosing cholangitis (PSC) is a biliary disease accompanied by chronic inflammation of the liver and biliary stricture. Mesenchymal stem cells (MSCs) are used to treat liver diseases because of their immune regulation and regeneration-promoting functions. This study was performed to explore the therapeutic potential of human placental MSCs (hP-MSCs) in PSC through the Takeda G protein-coupled receptor 5 (TGR5) receptor pathway. Liver tissues were collected from patients with PSC and healthy donors (n=4) for RNA sequencing and intrahepatic cholangiocyte organoid construction. hP-MSCs were injected via the tail vein into Mdr2-/-, bile duct ligation (BDL), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse models or co-cultured with organoids to confirm their therapeutic effect on biliary cholangitis. Changes in bile acid metabolic profile were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Compared with healthy controls, liver tissues and intrahepatic cholangiocyte organoids from PSC patients were characterized by inflammation and cholestasis, and marked downregulation of bile acid receptor TGR5 expression. hP-MSC treatment apparently reduced the inflammation, cholestasis, and fibrosis in Mdr2-/-, BDL, and DDC model mice. By activating the phosphatidylinositol 3 kinase/extracellular signal-regulated protein kinase pathway, hP-MSC treatment promoted the proliferation of cholangiocytes, and affected the transcription of downstream nuclear factor κB through regulation of the binding of TGR5 and Pellino3, thereby affecting the cholangiocyte inflammatory phenotype.

Long Noncoding RNA MIR600HG Binds to MicroRNA-125a-5p to Prevent Pancreatic Cancer Progression Via Mitochondrial Tumor Suppressor 1-Dependent Suppression of Extracellular Regulated Protein Kinases Signaling Pathway.

Significance of long noncoding RNAs in pancreatic cancer (PC) progression has been documented. Here, we identified a novel long noncoding RNA MIR600HG in PC and its underlying mechanism during PC progression. Through bioinformatics analysis, we selected MIR600HG, microRNA-125a-5p (miR-125a-5p), and mitochondrial tumor suppressor 1 (MTUS1) as objects with their expression patterns assayed in the collected PC tissues and PC cells. Pancreatic cancer cells were manipulated with ectopic expression and deficiency of MIR600HG, miR-125a-5p, and/or MTUS1 for assaying cell biological processes in vitro and tumorigenesis in vivo. MIR600HG and MTUS1 levels were downregulated and miR-125a-5p was upregulated in PC tissues and cells. MIR600HG could bind to miR-125a-5p, while miR-125a-5p negatively targeted MTUS1. MIR600HG resulted in suppression in malignant properties of PCs. All these changes could be reversed by miR-125a-5p elevation. In addition, miR-125a-5p targeted MTUS1 to activate the extracellular regulated protein kinases signaling pathway. In vivo experiment also verified the inhibitory role of MIR600HG in PC. Taken together, MIR600HG acts as an inhibitor for PC progression by upregulating miR-125a-5p-mediated MTUS1 through extracellular regulated protein kinases pathway.

Sphingosine 1-phosphate receptor 2 mediated early stages of pancreatic and systemic inflammatory responses via NF-kappa B activation in acute pancreatitis

In acute pancreatitis, activation of inflammatory signaling, including the nuclear factor-kappa B (NF-κB) pathway, within acinar cells is known to be an early intracellular event occurring in parallel with pathologic trypsinogen activation. Sphingosine 1-phosphate receptor 2 (S1PR2) plays a critical role in endothelial inflammation, and our previous studies reported that S1PR2 deficiency significantly reduced the inflammatory response in liver injury under cholestasis conditions. However, the role of S1PR2 in inflammatory signaling activation within acinar cells and inflammatory responses during acute pancreatitis has not been elucidated. Here we report that S1PR2 was upregulated in the whole pancreas during acute pancreatitis. Blockade of S1PR2 by pharmacologic inhibition of S1PR2 by JTE-013 or AAV-mediated knockdown of S1PR2 improved the severity of pancreatic injury, as indicated by a significant reduction in inflammation and acinar cells death in acute pancreatitis mice. Moreover, S1PR2 is the predominant S1PRs expressed in pancreatic acinar cells and mediates NF-κB activation and the early inflammatory response within acinar cells under acute pancreatitis conditions via ROCK signaling pathways, not extracellular signal-regulated kinase pathways or p38 mitogen-activated protein kinase pathways. In addition, S1PR2 mediated macrophage NF-κB activation, migration and polarization toward the M1 phenotype. Therefore, these results demonstrated that the S1PR2-mediated early inflammatory response in acinar cells promotes the progression of acute pancreatitis, successfully linking local events to the systematic inflammatory response and leading to a novel therapeutic target for acute pancreatitis aimed at halting the progression of the inflammatory response.4Upw5czRUXogyYiQEsPybuVideo

Molecular target therapeutics of EGF-TKI and downstream signaling pathways in non-small cell lung cancers.

Lung carcinoma (LC) is the third most common cancer diagnosis and accounted for the most cancer-related mortality worldwide in 2018. Based on the type of cells from which it originates, LC is commonly classified into non-small cell lung cancers (NSCLC) and small cell lung cancers (SCLC). NSCLC account for the majority of LC and can be further categories into adenocarcinoma, large cell carcinoma, and squamous cell carcinoma. Accurate classification of LC is critical for its adequate treatment and therapeutic outcome. Since NSCLC express more epidermal growth factor receptor (EGFR) with activation mutations, targeted therapy EGFR-tyrosine kinase inhibitors (TKIs) have been considered as primary option of NSCLC patients with activation EGFR mutation. In this review, we present the genetic alterations, reported mutations in EGFR, and TKIs treatment in NSCLC patients with an emphasis on the downstream signaling pathways in NSCLC progression. Among the signaling pathways identified, mitogen activation protein kinase (MAPK), known also as extracellular signal-regulated protein kinase (Erk) pathway, is the most investigated among the related pathways. EGFR activation leads to the autophosphorylation of its kinase domain and subsequent activation of Ras, phosphorylation of Raf and MEK1/2, and the activation of ERK1/2. Phosphatidylinositol 3-kinase (PI3K)/Akt is another signal pathway that regulates cell cycle and has been linked to NSCLC progression. Currently, three generations of EGFR TKIs have been developed as a first-line treatment of NSCLC patients with EGFR activation and mutation in which these treatment options will be further discussed in this review. The Supplementary Appendix for this article is available at http://links.lww.com/JCMA/A138.

Regulatory Mechanism of Neurotrophin Receptor-Interacting Melanoma Antigen Coding Gene Homolog (NRAGE) Gene Methylation on Apoptosis of Breast Cancer Cell Under Tyrosine Kinases/Methyl Ethyl Ketone/Extracellular Regulated Protein Kinases Signaling Pathway

The aim of this study was to discover the influence of Neurotrophin receptor-interacting MAGE homolog (NRAGE) gene methylation on proliferation (Pro) and apoptosis (Apo) of breast cancer cell (BCC), and its influence on TrkA/MEK/ERK signaling. BCC lines MCF-7, MDA-MB-231, and normal mammary gland cell (MGC) MCF-10 were selected. Expression of NRAGE mRNA and methylation level in cells was analyzed via reverse transcription-polymerase chain reaction (RT-PCR) and methylation-specific PCR. Different concentrations (0, 5, 10 mol/L) of DNA methylase inhibitor 5-aza-2′-deoxycytidine (5-Aza-CdR) were adopted to treat the BCC cell line. With dimethyl sulfoxide (DMSO) treatment as control, cell count, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, and Western blot were adopted to detect the Pro, Apo, relative expression (REP) of Apo-related proteins Bcl-2, Bax, and target proteins TrkA, MEK, and ERK1/2 after different treatments. The results showed that NRAGE mRNA level in MDA-MB-231 and MCF-7 was notably reduced versus MCF-10 (P < 0.05), and they could express methylated NRAGE specifically. 5-Aza-CdR can increase unmethylated NRAGE’s expression in BCC. Cell Pro level of the 5 and 10 mol/L treatments was greatly inhibited than DMSO and 0 mol/L treatments (P < 0.05). Apo rate and Apo-related proteins Bcl-2 and Bax increased obviously (P < 0.05). In addition, the phosphorylation levels of TrkA in the 5 and 10 mol/L treatments were considerably reduced (P < 0.05), while that in MEK and ERK1/2 was remarkably increased (P < 0.05). In short, NRAGE methylation can inhibit BCC’s Pro and regulate BCC’s Pro and Apo through TrkA/MEK/ERK signaling.

The Inhibitory Effect of Curcumin Derivative J147 on Melanogenesis and Melanosome Transport by Facilitating ERK-Mediated MITF Degradation.

The therapeutic use of curcumin and chemically modified curcumin (CMC) for suppressing melanogenesis and tyrosinase activity have been recognized. J147 is a modified version of curcumin with superior bioavailability and stability. However, there is no report about the effects of J147 on pigmentation in vitro and in vivo. In our studies, we investigated the hypopigmentary effects of J147 treatment on melanocytes and explored the underlying mechanism. The present studies suggested that J147 suppressed both basal and α-MSH-induced melanogenesis, as well as decreased melanocyte dendricity extension and melanosome transport. J147 played these roles mainly by activating the extracellular signal-regulated protein kinase (ERK) pathway. Once activated, it resulted in MITF degradation and further down-regulated the expression of tyrosinase, TRP-1, TRP-2, Myosin Va, Rab27a and Cdc42, ultimately inhibited melanin synthesis and melanosome transport. Furthermore, the hypopigmentary effects of J147 were demonstrated in vivo in a zebrafish model and UVB-induced hyperpigmentation model in brown guinea pigs. Our findings also suggested that J147 exhibited no cytotoxicity in vitro and in vivo. Taken together, these data confirmed that J147 may prove quite useful as a safer natural skin-whitening agent.

Implication of human endogenous retrovirus W family envelope in hepatocellular carcinoma promotes MEK/ERK-mediated metastatic invasiveness and doxorubicin resistance

Human endogenous retrovirus (HERVs), originating from exogenous retroviral infections of germ cells millions of years ago, have the potential for human diseases. Syncytin-1, an envelope protein encoded by the HERV W family, participates in the contexts of schizophrenia, multiple sclerosis, diabetes, and several types of cancers. Nevertheless, there is no report on the expression pattern and potential mechanism of Syncytin-1 in HCC. Here we found Syncytin-1 expression was up-regulated in HCC compared to adjacent non-tumorous tissues, especially in advanced HCC. Syncytin-1 was an independent risk factor to predict vascular invasion, metastasis, larger tumor size, and poor prognosis in HCC patients. Further analysis discovered that Syncytin-1 overexpression positively associated with HCC patients with serum HBsAg positive. Functional experiments in vitro and in vivo demonstrated that Syncytin-1 enhanced cell proliferation, metastasis, and tumorigenicity in HCC. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that the mitogen-activated protein kinase (MEK)/extracellular signal-regulated protein kinase (ERK) pathway was involved in HCC. Our clinical data indicated that the levels of phosphorylation MEK1/2 and ERK1/2 were increased in HCC comparing with adjacent non-tumorous tissues. It showed the linear correlation between Syncytin-1 expression and upregulated MEK1/2 and ERK1/2 phosphorylation levels in HCC. Furthermore, Syncytin-1 activated MEK/ERK pathway in HCC cells. In-depth research showed that the inflammation-activated MEK/ERK pathway was essential in Syncytin-1 promoted hepatocarcinogenesis. Syncytin-1 suppressed doxorubicin-induced apoptosis via MEK/ERK cascade. In conclusion, Syncytin-1 promoted HCC progression and doxorubicin resistance via the inflammation-activated MEK/ERK pathway. Our findings revealed that Syncytin-1 was a potential prognostic biomarker and therapeutic target for HCC.

Inhibition of 5-Lipoxygenase in Hepatic Stellate Cells Alleviates Liver Fibrosis.

Background and Purpose: Activation of hepatic stellate cells (HSC) is a central driver of liver fibrosis. 5-lipoxygenase (5-LO) is the key enzyme that catalyzes arachidonic acid into leukotrienes. In this study, we examined the role of 5-LO in HSC activation and liver fibrosis. Main Methods: Culture medium was collected from quiescent and activated HSC for target metabolomics analysis. Exogenous leukotrienes were added to culture medium to explore their effect in activating HSC. Genetic ablation of 5-LO in mice was used to study its role in liver fibrosis induced by CCl4 and a methionine-choline-deficient (MCD) diet. Pharmacological inhibition of 5-LO in HSC was used to explore the effect of this enzyme in HSC activation and liver fibrosis. Key Results: The secretion of LTB4 and LTC4 was increased in activated vs. quiescent HSC. LTB4 and LTC4 contributed to HSC activation by activating the extracellular signal-regulated protein kinase pathway. The expression of 5-LO was increased in activated HSC and fibrotic livers of mice. Ablation of 5-LO in primary HSC inhibited both mRNA and protein expression of fibrotic genes. In vivo, ablation of 5-LO markedly ameliorated the CCl4- and MCD diet-induced liver fibrosis and liver injury. Pharmacological inhibition of 5-LO in HSC by targeted delivery of the 5-LO inhibitor zileuton suppressed HSC activation and improved CCl4- and MCD diet-induced hepatic fibrosis and liver injury. Finally, we found increased 5-LO expression in patients with non-alcoholic steatohepatitis and liver fibrosis. Conclusion: 5-LO may play a critical role in activating HSC; genetic ablation or pharmacological inhibition of 5-LO improved CCl4-and MCD diet-induced liver fibrosis.

Silencing Aurora-kinase-A (AURKA) reinforced the sensitivity of diffuse large B-cell lymphoma cells to cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) via suppressing β-Catenin and RAS-extracellular signal-regulated protein kinase (ERK1/2) pathway

ABSTRACT The therapeutic effects of standard cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) therapy for prevalent lymphoma diffuse large B-cell lymphoma (DLBC, DLBCL) still require improvement. Cancer-related aurora-kinase-A (AURKA) may work as a target for DLBCL treatment and its effect on CHOP therapy was investigated in the present study. The Gene Expression Profiling Interactive Analysis 2 was applied to analyze AURKA expression in DLBC tumor tissues and normal lymphoid tissues. The DLBCL tissues and normal lymphoid tissues were obtained from the DLBCL patients and healthy volunteers. Clinic data of patients were recorded, and AURKA expression in tissues and cells was detected and analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry. After AURKA in DLBCL cells was silenced or overexpressed and treated with CHOP, viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. Expressions of AURKA, β-Catenin, phosphorylated (p)-β-Catenin, extracellular signal-regulated protein kinase (ERK1/2), p-ERK1/2 and RAS were detected using qRT-PCR and Western blot. AURKA was highly expressed in DLBCL tissues and cells. Silencing AURKA inhibited AURKA expression and viability, but promoted apoptosis of DLBCL cells. CHOP had no obvious effects on AURKA expression while reducing viability and promoting apoptosis of DLBCL cells. Silencing AURKA enhanced the effects of CHOP on cell apoptosis of DLBCL cells by inhibiting the expressions of RAS and β-Catenin as well as the ratio of p-ERK1/2/ERK1/2 and promoting the ratio of p-β-Catenin/β-Catenin. Silencing AURKA reinforced the therapeutic effects of CHOP on reducing viability and promoting apoptosis of DLBCL cell via repressing β-Catenin and RAS-ERK1/2 pathway.

Nitric oxide induces HepG2 cell death via extracellular signal-regulated protein kinase activation by regulating acid sphingomyelinase.

Nitric oxide (NO) plays a vital role in the occurrence and development of tumours. Acid sphingomyelinase (ASM) participates in cell apoptosis, cell proliferation, metabolism and other biological processes. However, whether ASM has an effect on NO-treated HepG2 cells remains unknown, and the role of the extracellular signal-regulated protein kinase (ERK) pathway is also unclear. In the present study, the effects of NO on cell viability and apoptosis were assayed, followed by investigating the mRNA and protein levels of ASM and ERK phosphorylation in NO-treated HepG2 cells. The results showed that diethylenetriamine/NO (DETA-NO), an NO donor, promoted HepG2 cell death and apoptosis in a concentration-dependent manner and that the mRNA and protein expression levels of ASM were significantly decreased in DETA-NO-treated HepG2 cells. Moreover, ERK phosphorylation was significantly increased in DETA-NO-treated HepG2 cells. The inhibition of ERK phosphorylation increased DETA-NO-induced cell apoptosis. In summary, DETA-NO can promote HepG2 cell death in a concentration-dependent manner by activating ERK and NO might activate ERK by regulating ASM and then inducing HepG2 cell death.

Platelet-rich Fibrin Improves the Osteo-/Odontogenic Differentiation of Stem Cells from Apical Papilla via the Extracellular Signal–regulated Protein Kinase Signaling Pathway

IntroductionThe aim of this study was to investigate the cytobiological effects of platelet-rich fibrin (PRF) on stem cells from the apical papilla (SCAPs) in vitro and to further explore the underlying molecular mechanisms. MethodsSCAPs were isolated from immature third molars. Different concentrations of PRF conditioned medium (one eighth, one quarter, and one half PRF) were prepared. After pretreatment with PRF, the proliferation rate and migration capacity of SCAPs were examined by the Cell Counting Kit-8 assay and wound healing assay, respectively. Alizarin red S staining was performed to examine mineralized nodule formation. Western blot analysis was used to detect the expression of osteo-/odontogenic markers and the extracellular signal–regulated kinase (ERK) pathway in SCAPs. Data were analyzed by one-way analysis of variance. P values <.05 were considered statistically significant. ResultsThe Cell Counting Kit-8 assay showed that one eighth PRF improved the proliferation rate and the migration capacity of SCAPs (P < .005), whereas one quarter PRF and one half PRF showed no significant difference compared with the control group. The expression of osteo-/odontogenic markers and the capacity to form mineralized nodules of SCAPs were promoted by one eighth PRF and one quarter PRF. In addition, PRF activated ERK signaling, and the ERK inhibitor attenuated PRF-induced osteo-/odontogenesis of SCAPs. ConclusionsPRF improved the osteo-/odontogenic differentiation of SCAPs by activating the ERK pathway; meanwhile, PRF improved the proliferation and migration of SCAPs, and one eighth PRF achieved the most obvious promotion effect. The favorable cytobiological effects of PRF on SCAPs might serve as basis for PRF applications in regenerative endodontic treatment.

Isoliquiritigenin inhibits melanogenesis, melanocyte dendricity and melanosome transport by regulating ERK-mediated MITF degradation.

Isoliquiritigenin (ISL), a flavonoid component from the hydrolysis products of licorice root. It has been reported that ISL inhibited melanogenesis by suppressing the tyrosinase activity in human melanocytes. Recently, ISL was found to induce melanin degradation in human epidermal keratinocytes. However, the role of ISL in pigmentation is not fully understood. In the current study, we aimed to investigate the effects of ISL on pigmentation, and further explored the underlying mechanism. Our results suggested that ISL suppressed basal and α-MSH-, ACTH- and UV-induced melanin synthesis, in addition to inhibiting melanocyte dendricity and melanosome transport. ISL played these roles mainly by activating the extracellular signal-regulated protein kinase pathway. Once activated, it induced microphthalmia-associated transcription factor degradation and decreased the expression of tyrosinase, TRP-1, DCT, Rab27a and Cdc42, finally inhibited melanogenesis, melanocyte dendricity and melanosome transport. Our findings suggested that ISL exhibited no cytotoxicity in our research, it may prove quite useful as a safer natural skin-whitening agent.

The Effect of Protein FAM172A on Proliferation in HepG2 Cells and Investigation of the Possible Molecular Mechanism.

Background In our previous study, we found that the FAM172A recombinant protein could promote proliferation of L02 cells. However, the underlying mechanisms are still unknown. The present study was aimed at investigating the effect of FAM172A on proliferation of HepG2 cells and exploring the possible molecular mechanisms and its role in hepatocellular carcinoma (HCC). Methods Cell proliferation was measured by MTT assay. Western blot test was carried out to investigate the mechanism. Rabbit antibodies against FAM172A and membrane proteins isolated from lysate of HepG2 cell were coprecipitated and the resultant precipitates were analyzed by mass spectrum. Results The MTT assay showed that recombinant protein FAM172A isoform 1 (FAM172A-1) could induce HepG2 cell proliferation at the concentration of 10-100 ng/mL, while protein FAM172A isoform 3 (FAM172A-3) was at the concentration of 80-100 ng/mL. Western blot demonstrated that both FAM172A-1 and FAM172A-3 could activate the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) pathway and the phosphatidylinositol 3-kinase/threonine-protein kinase (PI3K/Akt) pathway. Mass spectrum analysis suggested that there were some membrane proteins interacting with FAM172A. Several candidate interacting proteins might mediate proliferation signals induced by FAM172A recombinant protein, including seven membrane proteins. Conclusion In conclusion, FAM172A recombinant protein could induce proliferation of HepG2 cells, in which the MAPK/ERK and PI3K/Akt signaling pathways might be involved. The role of FAM172A in HepG2 cell proliferation also indicated its possible involvement in HCC. The receptor of FAM172A on cells still needs to be exploited.

Potential therapeutic effect of SO₂ on fibrosis.

Fibrosis is a pathological feature of most chronic diseases and leads to the dysfunction of various organs. However, there is currently no effective method for treating fibrosis. In recent years, a small gas, sulfur dioxide (SO₂), which can be generated endogenously in mammals, has been found to have vasorelaxation activity, improve cardiac function and decrease myocardial injury. Endogenous SO₂ also mediates the process of fibrosis. Inhibition of endogenous SO₂ can aggravate small pulmonary artery remodeling and abnormal collagen accumulation. SO₂ treatment significantly improves pulmonary fibrosis and pulmonary arterial remodeling. Overexpression of the key enzymes associated with endogenous SO₂ generation, aspartate aminotransferase (AAT) 1 and AAT2, mimics the effect of SO₂ on the down-regulation of collagen synthesis, while AAT1 or AAT2 knockdown aggravates abnormal collagen accumulation in vascular smooth muscle cells (VSMCs). SO₂ also improves myocardial fibrosis induced by myocardial infarction or diabetes in rats, and inhibits myocardial fibroblast proliferation and migration by the extracellular signal-regulated protein kinase pathway. The mechanisms underlying the inhibition of fibrosis by SO₂ are related to its antioxidant effect, anti-inflammation effect, improvement in cardiac function, and cell proliferation inhibition. Therefore, SO₂ has a potential therapeutic effect on fibrosis.

Functional RNAi Screens Define Distinct Protein Kinase Vulnerabilities in EGFR-Dependent HNSCC Cell Lines.

The inhibitory epidermal growth factor receptor (EGFR) antibody, cetuximab, is an approved therapy for head and neck squamous cell carcinoma (HNSCC). Despite tumor response observed in some HNSCC patients, cetuximab alone or combined with radio- or chemotherapy fails to yield long-term control or cures. We hypothesize that a flexible receptor tyrosine kinase coactivation signaling network supports HNSCC survival in the setting of EGFR blockade, and that drugs disrupting this network will provide superior tumor control when combined with EGFR inhibitors. In this work, we submitted EGFR-dependent HNSCC cell lines to RNA interference-based functional genomics screens to identify, in an unbiased fashion, essential protein kinases for growth and survival as well as synthetic lethal targets for combined inhibition with EGFR antagonists. Mechanistic target of rapamycin kinase (MTOR) and erythroblastosis oncogene B (ERBB)3 were identified as high-ranking essential kinase hits in the HNSCC cell lines. MTOR dependency was confirmed by distinct short hairpin RNAs (shRNAs) and high sensitivity of the cell lines to AZD8055, whereas ERBB3 dependency was validated by shRNA-mediated silencing. Furthermore, a synthetic lethal kinome shRNA screen with a pan-ERBB inhibitor, AZD8931, identified multiple components of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase pathway, consistent with ERK reactivation and/or incomplete ERK pathway inhibition in response to EGFR inhibitor monotherapy. As validation, distinct mitogen-activated protein kinase kinase (MEK) inhibitors yielded synergistic growth inhibition when combined with the EGFR inhibitors, gefitinib and AZD8931. The findings identify ERBB3 and MTOR as important pharmacological vulnerabilities in HNSCC and support combining MEK and EGFR inhibitors to enhance clinical efficacy in HNSCC. SIGNIFICANCE STATEMENT: Many cancers are driven by nonmutated receptor tyrosine kinase coactivation networks that defy full inhibition with single targeted drugs. This study identifies erythroblastosis oncogene B (ERBB)3 as an essential protein kinase in epidermal growth factor receptor-dependent head and neck squamous cell cancer (HNSCC) cell lines and a synthetic lethal interaction with the extracellular signal-regulated kinase mitogen-activated protein kinase pathway that provides a rationale for combining pan-ERBB and mitogen-activated protein kinase inhibitors as a therapeutic approach in subsets of HNSCC.

Four new tirucallane-type triterpenoids from Sapindus mukorossi Gaertn. flowers induced neurite outgrowth in PC12 cells related to insulin-like growth factor 1 receptor/phosphoinositide 3-kinase/extracellular regulated protein kinase signaling pathway

Four new tirucallane-type saponins (i.e., sapinmusaponin S–V, which include one new structure and three new stereoisomers) and a known compound sapinmusaponin G were isolated from the flowers of Sapindus mukorossi. All of them could significantly induce neurite outgrowth of PC12 cells. The structures of active compounds were determined using spectroscopic data and chemical derivatization. Specific inhibitor experiments and Western blot analysis of sapinmusaponin S, which is the most active compound, were performed. Results indicated that the insulin-like growth factor 1 receptor/phosphoinositide 3-kinase/extracellular regulated protein kinase signaling pathway is involved in this action.

Inhibiting c-Jun N-terminal kinase (JNK)-mediated apoptotic signaling pathway in PC12 cells by a polysaccharide (CCP) from Coptis chinensis against Amyloid-β (Aβ)-induced neurotoxicity

In this study, we investigated the protective effect and possible mechanism of a polysaccharide (CCP) from Coptis chinensis against Amyloid-β protein (Aβ)-induced toxicity in PC12 cells. The results showed pretreatment with CCP significantly protected PC12 cells from Aβ25–35 induced cell death, lactate dehydrogenase (LDH) release, nuclear fragmentation, mitochondrial dysfunction and cytochrome c release from mitochondria. Furthermore, CCP (100 μg/ml) significantly inhibited Aβ25–35 induced c-Jun N-terminal kinase (JNK) phosphorylation, but not influence signal-regulated kinase (ERK) and P38 mitogen-activated protein kinase (p38MAPK) pathway, and interestingly, the promoting effect of CCP on PC12 cell survival was only blocked by pre-treatment with a SP600125 (JNK inhibitor). In addition, Aβ25–35-induced increase of Bax and cleaved caspase-3, as well as decrease of Bcl-2 protein expression was markedly reversed by CCP or SP600125. Thus, our results indicate that the neuroprotective effect of CCP is associated with JNK-dependent apoptotic pathway.

Ganglioside Hp-s1 Analogue Inhibits Amyloidogenic Toxicity in Alzheimer's Disease Model Cells.

Alzheimer's disease (AD) is characterized by extracellular deposition of amyloid plaques, which are predominantly composed of amyloid-β (Aβ) peptide derived from amyloid precursor protein (APP) cleavage. APP interacts with tropomyosin receptor kinase A, a neurotrophic receptor associated with gangliosides and mediating neuronal survival and differentiation through the extracellular signal-regulated protein kinase (ERK) pathway. The ganglioside Hp-s1's analogue Hp-s1A exerts neuritogenic activity; however, its effect on AD pathology remains unknown. To test the hypothesis that Hp-s1A is a potential candidate to treat AD, we established the AD-modeled cell line by expressing human Swedish and Indiana APP gene (APP-Swe/Ind) in N2a mouse neuroblastoma cells. The cells were treated with Hp-s1A or monosialoganglioside GM1 for comparison. The AD model cells expressing APP-Swe/Ind exhibited a significant reduction in viability, as well as neurite outgrowth rate, in comparison to the control cells expressing APP-695. APP C-terminal fragment-β (CTFβ) and Aβ42 were increased in the AD cell lysates and the culture media, respectively. With the treatment of either Hp-s1A or GM1 at 1 μM, the AD model cells showed a significant increase in viability; however, only Hp-s1A reduced CTFβ levels in these cells. Further analysis of the culture media revealed that Hp-s1A also reduced Aβ42 production from AD model cells. The phosphorylation of ERK was elevated and the neurite outgrowth rate was restored with Hp-s1A treatment. In conclusion, the ganglioside analogue Hp-s1A inhibited amyloidogenic processing of APP and promoted neurotrophic activity and survival of AD model cells. Hp-s1A has great potential in AD therapeutic development.