Extracellular Signal-regulated Kinase Mitogen-activated Protein Research Articles

Cerebral ischemia-reperfusion is modulated by macrophage-stimulating 1 through the MAPK-ERK signaling pathway.

Cerebral ischemia-reperfusion (IR) injury is associated with mitochondrial damage. Macrophage-stimulating 1 (MST1) reportedly stimulates mitochondrial apoptosis by suppressing BCL-2. We investigated whether MST1 promotes the progression of cerebral IR injury by inducing mitochondrial dysfunction in vivo and in vitro. Western blot analysis, quantitative polymerase chain reaction, immunofluorescence, and mitochondrial function assays were conducted in cells from wild-type and Mst1-knockout mice subjected to cerebral IR injury. MST1 expression in wild-type glial cells increased following cerebral IR injury. Cerebral IR injury reduced the mitochondrial membrane potential and mitochondrial metabolism in glial cells, while it enhanced mitochondrial reactive oxygen species generation and mitochondrial calcium levels in these cells. The deletion of Mst1 attenuated cerebral IR injury by improving mitochondrial function and reducing mitochondrial damage. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway was suppressed in wild-type glial cell upon cerebral IR injury but was reactivated in Mst1-knockout glial cell. Accordingly, blocking the MAPK/ERK pathway abolished the beneficial effects of Mst1 deletion during cerebral IR injury by inducing mitochondrial damage in glial cells. Our results suggest that cerebral IR injury is associated with MST1 upregulation in the brain, while the genetic ablation of Mst1 can attenuate mitochondrial damage and sustain brain function following cerebral IR injury.

Spinal AMP kinase activity differentially regulates phrenic motor plasticity.

Acute intermittent hypoxia (AIH) elicits phrenic motor plasticity via multiple distinct cellular mechanisms. With moderate AIH, phrenic motor facilitation (pMF) requires Gq protein-coupled serotonin type 2 receptor activation, ERK MAP kinase activity, and new synthesis of brain-derived neurotrophic factor. In contrast, severe AIH elicits pMF by an adenosine-dependent mechanism that requires exchange protein activated by cAMP, Akt, and mammalian target of rapamycin (mTOR) activity, followed by new tyrosine receptor kinase B protein synthesis; this same pathway is also initiated by Gs protein-coupled serotonin 7 receptors (5-HT7). Because the metabolic sensor AMP-activated protein kinase (AMPK) inhibits mTOR-dependent protein synthesis, and mTOR signaling is necessary for 5-HT7 but not 5-HT2 receptor-induced pMF, we hypothesized that spinal AMPK activity differentially regulates pMF elicited by these distinct receptor subtypes. Serotonin type 2A receptor [5-HT2A; (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride] or 5-HT7 (AS-19) receptor agonists were administered intrathecally at C4 (3 injections, 5-min intervals) while recording integrated phrenic nerve activity in anesthetized, vagotomized, paralyzed, and ventilated rats. Consistent with our hypothesis, spinal AMPK activation with 2-deoxyglucose or metformin blocked 5-HT7, but not 5-HT2A receptor-induced pMF; in both cases, pMF inhibition was reversed by spinal administration of the AMPK inhibitor compound C. Thus, AMPK differentially regulates cellular mechanisms of serotonin-induced phrenic motor plasticity.NEW & NOTEWORTHY Spinal AMP-activated protein kinase (AMPK) overactivity, induced by local 2-deoxyglucose or metformin administration, constrains serotonin 7 (5-HT7) receptor-induced (but not serotonin type 2A receptor-induced) respiratory motor facilitation, indicating that metabolic challenges might regulate specific forms of respiratory motor plasticity. Pharmacological blockade of spinal AMPK activity restores 5-HT7 receptor-induced respiratory motor facilitation in the presence of either 2-deoxyglucose or metformin, showing that AMPK is an important regulator of 5-HT7 receptor-induced respiratory motor plasticity.

Molecular characterization and expression analysis of two crucial MAPKs- jnk1 and erk1 as cellular signal transducers in Labeo rohita in response to PAMPs stimulation and pathogenic invasion.

Mitogen-activated protein kinases (MAPKs) are crucial Ser/Thr protein kinases that play important roles in innate immunity by converting extracellular stimuli into a wide range of cellular responses, including the production of cytokines. In this study, two MAPK genes, jnk1 and erk1, were cloned and characterized in rohu (Labeo rohita), a commercially important freshwater fish species in the Indian subcontinent. In healthy rohu, both jnk1 and erk1 gene expressions were highest in the spleen as compared to gill, liver, blood and kidney tissues. In vitro stimulation of the L. rohita gill (LRG) cell line with γ-D-glutamyl-meso-diaminopimelic acid, muramyl dipeptide and polyinosinic: polycytidylic acid (poly I:C) resulted in significantly enhanced expressions of jnk1 and erk1 genes. In the in vivo experiments, jnk1 and erk1 gene expressions were also enhanced in lipopolysaccharides and poly I:C-treatment. Infection of rohu fingerlings with Aeromonas hydrophila and Bacillus subtilis revealed significantly enhanced expressions of the jnk1 and erk1 genes in all of the tested organs/tissues. Together these results imply the important role of jnk1 and erk1 genes in fish during pathogenic invasion and diseases.

JAK-STAT-dependent regulation of scavenger receptors in LPS-activated murine macrophages

In atherosclerosis progression, atherosclerotic plaques develop upon accumulated foam cells derived from macrophages that take up modified low-density lipoprotein (LDL). CD36 and CD204 are the principal scavenger receptors responsible for the uptake of modified LDL. Lipopolysaccharide (LPS) exacerbates atherosclerosis by enhancing the expression of scavenger receptors and thus increasing the uptake of modified LDL into macrophages. However, the signaling pathways that mediate LPS and scavenger receptor expression have not been fully elucidated.We used mouse bone marrow-derived macrophages and investigated the effects of LPS in vitro. LPS enhanced the phosphorylation of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription-1 (STAT-1). Inhibitors of the mitogen-activated protein kinase (MAPK)/ERK kinase (MEK) pathway (U0126 and PD0325901) suppressed the uptake of acetylated-LDL (Ac-LDL) and the expression of CD204 but not CD36 in LPS-activated macrophages. Inhibitors of the Janus tyrosine kinase (JAK)-STAT pathway (ruxolitinib and tofacitinib) suppressed the uptake of Ac-LDL and the expression of both CD36 and CD204 in LPS-activated macrophages. We next injected LPS into the peritoneal cavity of mice and analyzed the effects of LPS. MEK inhibitor U0126 suppressed the uptake of Ac-LDL and the expression of CD204 but not CD36 in LPS-activated macrophages. JAK inhibitor ruxolitinib suppressed the uptake of Ac-LDL and the expression of both CD36 and CD204 in LPS-activated macrophages. These results suggest that scavenger receptors in LPS-activated mouse macrophages are regulated through a JAK-STAT-dependent pathway. Although further evaluation is necessary, JAK-STAT inhibition could be useful in atherosclerosis therapy, at least for atherosclerosis exacerbated by LPS.

Trametinib alleviates lipopolysaccharide-induced acute lung injury by inhibiting the MEK-ERK-Egr-1 pathway

Acute lung injury (ALI) is a devastating clinical disorder with a high mortality rate and for which there is no effective treatment. The main characteristic of ALI is uncontrolled inflammation, and macrophages play a critical role in the development of this disorder. Trametinib, an inhibitor of MAPK/ERK kinase (MEK) activity that possesses anti-inflammatory properties, has been approved for clinical use. Herein, the influence of trametinib and its underlying mechanism were investigated using a lipopolysaccharide (LPS)-induced murine ALI model. We found that trametinib treatment prevented the LPS-facilitated expression of proinflammatory mediators in macrophages, and this anti-inflammatory action was closely correlated with suppression of the MEK-ERK-early growth response (Egr)-1 pathway. Furthermore, trametinib treatment alleviated LPS-induced ALI in mice, and attenuated edema, proinflammatory mediator production, and neutrophil infiltration. Trametinib pretreatment also attenuated the MEK-ERK-Egr-1 pathway in lung tissues. In conclusion, these data demonstrate that trametinib pretreatment suppresses inflammation in LPS-activated macrophages in vitro and protects against murine ALI established by LPS administration in vivo through inhibition of the MEK-ERK-Egr-1 pathway. Therefore, trametinib might have therapeutic potential for ALI.

Activation-induced substrate engagement in ERK signaling.

The extracellular signal-regulated kinase (ERK) pathway is an essential component of developmental signaling in metazoans. Previous models of pathway activation suggested that dissociation of activated dually phosphorylated ERK (dpERK) from MAPK/ERK kinase (MEK), a kinase that phosphorylates ERK, and other cytoplasmic anchors, is sufficient for allowing ERK interactions with its substrates. Here, we provide evidence for an additional step controlling ERK’s access to substrates. Specifically, we demonstrate that interaction of ERK with its substrate Capicua (Cic) is controlled at the level of ERK phosphorylation, whereby Cic binds to dpERK much stronger than to unphosphorylated ERK, both in vitro and in vivo. Mathematical modeling suggests that the differential affinity of Cic for dpERK versus ERK is required for both down-regulation of Cic and stabilizing phosphorylated ERK. Preferential association of Cic with dpERK serves two functions: it prevents unproductive competition of Cic with unphosphorylated ERK and contributes to efficient signal propagation. We propose that high-affinity substrate binding increases the specificity and efficiency of signal transduction through the ERK pathway.

Bisphenol A Exposure Enhances Endometrial Stromal Cell Invasion and Has a Positive Association with Peritoneal Endometriosis.

Results of previous epidemiology studies on BPA exposure and endometriosis (EMs) risk were inconsistent, and were limited by inappropriate control selection, incorrect BPA detection method, and the generalization of different subtypes of EMs. Upregulated matrix metalloproteinase (MMP) 2 and MMP9 are involved in the development of EMs. We conducted a case-control study among 120 EMs patients and 100 healthy women to evaluate the relationships between BPA exposure and MMP2, MMP9 expressions, and the risk of EMs subtypes. Besides, we used human endometrial stromal cell lines (HESCs) to investigate the underlying mechanisms. Creatinine-adjusted urinary BPA concentrations were positively correlated with serum MMP2, MMP9 levels, and the risk of peritoneal EMs (third vs lowest quartile: OR 4.92, 95% CI 1.47, 16.50; fourth versus lowest quartile: OR 3.70, 95% CI 1.07, 12.74, Ptrend = 0.030). The risk of peritoneal EMs increased approximately tenfold when creatinine-adjusted urinary BPA concentration was 2μg/g. In vitro study found that BPA exposure increased MMP2, MMP9 expressions in a dose-dependent manner. The effects of BPA on HESCs could be blocked by G protein-coupled estrogen receptor (GPER) inhibitor or mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) inhibitor. This study provides evidence that BPA exposure promotes peritoneal EMs, and raises a concern about the potential toxicity of BPA on the female reproductive system.

Effects of propofol on proliferation and apoptosis of cardia cancer cells via MAPK/ERK signaling pathway.

To explore the influences of propofol on the proliferation and apoptosis of cardia cancer cells via mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway. A total of 65 surgical resection specimens of cardia cancer were selected as research objects and divided into control group and with low (12.5 μmol/L), medium (25 μmol/L), and high (50 μmol/L) propofol concentration groups. The apoptosis of cancer cells, ERK1/2 phosphorylation level, expressions of Caspase-3, B-cell lymphoma-2 (Bcl-2), and Bcl-2 associated X protein (Bax) in each group were detected. Propofol in different concentrations could all effectively inhibit the proliferation of cardia cancer cells in a dose-dependent manner. Different concentrations of propofol promoted the apoptosis of cardia cancer cells, and the apoptosis rate constantly increased with the rising concentration of propofol (p<0.05). Propofol could repress the expression of Bcl-2 and up-regulate the expression levels of Caspase-3, Bax, and phosphorylated ERK1/2. Propofol can inhibit the proliferation and induce the apoptosis of cardia cancer cells, and the action mechanism may be correlated with the inhibition on the MAPK/ERK signaling pathway.

MiR-19 Promotes Cell Proliferation, Invasion, Migration, and EMT by Inhibiting SPRED2-mediated Autophagy in Osteosarcoma Cells

Osteosarcoma is an aggressive malignancy with rapid development and poor prognosis. microRNA-19 (miR-19) plays an important role in several biological processes. Sprouty-related EVH1 domain protein 2 (SPRED2) is a suppressor of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signaling to inhibit tumor development and progression by promoting autophagy. In this study, we investigated the roles of miR-19, SPRED2, and autophagy in osteosarcoma. We detected the expression of miR-19, SPRED2, epithelial–mesenchymal transition (EMT) markers, and autophagy-related proteins via quantitative real-time polymerase chain reaction or western blot. To evaluate the function of miR-19 and SPRED2, we used MTT and colony formation assays to detect cell proliferation, Transwell, and wound-healing assays to detect cell invasion and migration. Targetscan and luciferase reporter assays confirmed the relationship between SPRED2 and miR-19. The expression of miR-19 was significantly upregulated in osteosarcoma, while SPRED2 was downregulated. miR-19 inhibitor reduced cell proliferation, invasion, migration, and EMT, while its cell biological effects were partially reversed by addition of autophagy inhibitor 3-methyladenine (3-MA) or SPRED2 siRNA in osteosarcoma. SPRED2, a suppressor of ERK/MAPK pathway that is known to trigger autophagy, was identified as a direct target of miR-19. SPRED2 overexpression increased cell proliferation, invasion, migration, and EMT by promoting autophagy, and the effects could be inhibited by 3-MA. Collectively, these findings reveal an underlying mechanism for development of osteosarcoma. miR-19 was upregulated in osteosarcoma cells, and negatively regulated SPRED2, thus promoting the malignant transformation of osteosarcoma cells via inhibiting SPRED2-induced autophagy. Therefore, miR-19/SPRED2 may be a potential target for the treatment of osteosarcoma.

The Synthetic Curcumin Derivative CNB-001 Attenuates Thrombin-Stimulated Microglial Inflammation by Inhibiting the ERK and p38 MAPK Pathways.

We have recently found that the synthetic curcumin derivative CNB-001 suppresses lipopolysaccharide (LPS)-induced nitric oxide (NO) production in cultured microglia, demonstrating that it exerts anti-neuroinflammatory effects by regulating microglial activation. To explore the molecular mechanisms underlying the anti-inflammatory effect of CNB-001, the present study investigated whether CNB-001 is also effective for microglial NO production induced by other stimulants than LPS. Treatment of primary cultured rat microglia with thrombin, a serine protease that has been proposed as a mediator of cerebrovascular injuries, caused the expression of inducible NO synthase (iNOS) and the production of NO. The thrombin-induced NO production was completely blocked by the presence of SCH-79797, a selective protease-activated receptor 1 (PAR-1) antagonist, suggesting that the effect of thrombin is mediated by PAR-1. CNB-001 (1-10 µM) attenuated the thrombin-induced iNOS expression and NO production without affecting the PAR-1 expression. In addition, thrombin treatment caused rapid phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK). The changes in ERK and p38 MAPK were significantly suppressed by the presence of CNB-001. These results demonstrate that CNB-001 suppresses thrombin-stimulated microglial activation by inhibiting the ERK and p38 MAPK pathways.

Adamantinomatous craniopharyngioma: moving toward targeted therapies.

The evolving characterization of the biological basis of adamantinomatous craniopharyngioma (ACP) has provided insights critical for novel systemically delivered therapies. While current treatment strategies for ACP are associated with low mortality rates, patients experience severely lowered quality of life due to high recurrence rates and chronic sequelae, presenting a need for novel effective treatment regimens. The identification of various dysregulated pathways that play roles in the pathogenesis of ACP has prompted the investigation of novel treatment options. Aberrations in the CTNNB1 gene lead to the dysregulation of the Wnt pathway and the accumulation of nuclear β-catenin, which may play a role in tumor invasiveness. While Wnt pathway/β-catenin inhibition may be a promising treatment for ACP, potential off-target effects have limited its use in current intervention strategies. Promising evidence of the therapeutic potential of cystic proinflammatory mediators and immunosuppressants has been translated into clinical therapies, including interleukin 6 and IDO-1 inhibition. The dysregulation of the pathways of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK), epidermal growth factor receptor (EGFR), and programmed cell death protein 1 and its ligand (PD-1/PD-L1) has led to identification of various therapeutic targets that have shown promise as clinical strategies. The Sonic Hedgehog (SHH) pathway is upregulated in ACP and has been implicated in tumorigenesis and tumor growth; however, inhibition of SHH in murine models decreased survival, limiting its therapeutic application. While further preclinical and clinical data are needed, systemically delivered therapies could delay or replace the need for more aggressive definitive treatments. Ongoing preclinical investigations and clinical trials of these prospective pathways promise to advance treatment approaches aimed to increase patients' quality of life.

Molecular insights into kinase mediated signaling pathways of chemokines and their cognate G protein coupled receptors.

Chemokines are small regulatory proteins that play a crucial role in the coordinated migration of cell populations to the site of infection/inflammation by binding to their cognate receptors. In principle, chemokine receptors, which are serpentine G protein-coupled receptors (GPCRs), mediate the series of downstream intracellular signaling events that occur inside the cells to resolve the pathogenicity. Intracellular signaling pathways regulated by the kinase protein sub-families are the center of attention for chemokine derived functional responses. Kinases potentially influence cell migration, cell growth, transcriptional activation, and other essential molecular events. The regulation and flow of the signals by the kinases are different for each physiological and pathological event and are tightly regulated by the nature and pairing of chemokine(s) with its receptor(s). For example, phosphoinositide 3-kinase (PI3K) is activated during the initial steps of the chemokine induced signaling cascade to regulate chemotaxis, transcription, and cell survival. G protein-coupled receptor kinase (GRKs) plays a crucial role in the desensitization and internalization of the chemokine receptors. The regulation of chemokine receptor is also governed by kinases like protein kinase A (PKA), protein kinase C (PKC), mitogen-activated protein kinases / extracellular signal-regulated kinases (MAPK/ERK), etc. It was also established that tyrosine-protein kinases (TECs) such as ITK and RLK play a significant role in chemokine signaling in T lymphocytes. On a similar note, many others like janus kinases (JAKs), Protein kinase B (PKB), PKC, etc. are also studied in chemokine mediated disease models. The present review elucidates the role of different kinases involved in the chemokine/chemokine receptor mediated signaling cascade during various pathophysiological processes.

Antiproliferative effect of mifepristone (RU486) on human neuroblastoma cells (SK-N-SH): in vitro and in vivo studies.

RU486 (mifepristone), a glucocorticoid and progesterone receptor antagonist, has been reported to exert antiproliferative effects on tumor cells. Experiments were performed to analyze the effects of RU486 on the proliferation of the human neuroblastoma, both in vitro and in vivo, using the human neuroblastoma SK-N-SH cell line. The exposure in vitro of SK-N-SH cells to RU486 revealed a dose-dependent inhibition of 3H-thymidine incorporation due to a rapid but persistent inhibition of MAPKinase activity and ERK phosphorylation. A significant decrease of SK-N-SH cell number was evident after 3, 6, and 9 days of treatment (up to 40% inhibition), without evident cell death. The inhibitory effect exerted by RU486 was not reversed by the treatment of the cells with dexamethasone or progesterone. Moreover, RU486 induced a shift in SK-N-SH cell phenotypes, with an almost complete disappearance of the neuronal-like and a prevalence of the epithelial-like cell subtypes. Finally, the treatment with RU486 of nude mice carrying a SK-N-SH cell xenograft induced a strong inhibition (up to 80%) of tumor growth. These results indicated a clear effect of RU486 on the growth of SK-N-SH neuroblastoma cells that does not seem to be mediated through the classical steroid receptors. RU486 acted mainly on the more aggressive component of the SK-N-SH cell line and its effect in vivo was achieved at a concentration already used to inhibit oocyte implantation.

Focal Adhesion Kinase Promotes Hepatic Stellate Cell Activation by Regulating Plasma Membrane Localization of TGFβ Receptor 2.

Transforming growth factor β (TGFβ) induces hepatic stellate cell (HSC) differentiation into tumor‐promoting myofibroblast, although underlying mechanism remains incompletely understood. Focal adhesion kinase (FAK) is activated in response to TGFβ stimulation, so it transmits TGFβ stimulus to extracellular signal‐regulated kinase and P38 mitogen‐activated protein kinase signaling. However, it is unknown whether FAK can, in return, modulate TGFβ receptors. In this study, we tested whether FAK phosphorylated TGFβ receptor 2 (TGFβR2) and regulated TGFβR2 intracellular trafficking in HSCs. The FAKY397F mutant and PF‐573,228 were used to inhibit the kinase activity of FAK, the TGFβR2 protein level was quantitated by immunoblotting, and HSC differentiation into myofibroblast was assessed by expression of HSC activation markers, alpha‐smooth muscle actin, fibronectin, or connective tissue growth factor. We found that targeting FAK kinase activity suppressed the TGFβR2 protein level, TGFβ1‐induced mothers against decapentaplegic homolog phosphorylation, and myofibroblastic activation of HSCs. At the molecular and cellular level, active FAK (phosphorylated FAK at tyrosine 397) bound to TGFβR2 and kept TGFβR2 at the peripheral plasma membrane of HSCs, and it induced TGFβR2 phosphorylation at tyrosine 336. In contrast, targeting FAK or mutating Y336 to F on TGFβR2 led to lysosomal sorting and degradation of TGFβR2. Using RNA sequencing, we identified that the transcripts of 764 TGFβ target genes were influenced by FAK inhibition, and that through FAK, TGFβ1 stimulated HSCs to produce a panel of tumor‐promoting factors, including extracellular matrix remodeling proteins, growth factors and cytokines, and immune checkpoint molecule PD‐L1. Functionally, targeting FAK inhibited tumor‐promoting effects of HSCs in vitro and in a tumor implantation mouse model. Conclusion: FAK targets TGFβR2 to the plasma membrane and protects TGFβR2 from lysosome‐mediated degradation, thereby promoting TGFβ‐mediated HSC activation. FAK is a target for suppressing HSC activation and the hepatic tumor microenvironment.

The Glucosamine-derivative NAPA Suppresses MAPK Activation and Restores Collagen Deposition in Human Diploid Fibroblasts Challenged with Environmental Levels of UVB.

The ultraviolet (UV) component of solar radiation is the driving force of life on earth, but it can cause photoaging and skin cancer. In this study, we investigated the effects of the glucosamine-derivative 2-(N-Acetyl)-L-phenylalanylamido-2-deoxy-β-D-glucose (NAPA) on human primary fibroblasts (FBs) stimulated in vitro with environmental levels of UVB radiation. FBs were irradiated with 0.04Jcm-2 UVB dose, which resulted a mild dosage as shown by the cell viability and ROS production measurement. This environmental UVB dose induced activation of MAP kinase ERK 1/2, the stimulation of c-fos and at lower extent of c-jun, and in turn AP-1-dependent up-regulation of pro-inflammatory factors IL-6 and IL-8 and suppression of collagen type I expression. On the contrary, 0.04Jcm-2 UVB dose was not able to stimulate metalloprotease production. NAPA treatment was able to suppress the up-regulation of IL-6 and IL-8 via the inhibition of MAP kinase ERK phosphorylation and the following AP-1 activation, and was able to attenuate the collagen type I down-regulation induced by the UVBs. Taken together, our results show that NAPA, considering its dual action on suppression of inflammation and stimulation of collagen type I production, represents an interesting candidate as a new photoprotective and photorepairing agents.

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.

Abstract C30: Myc amplification is a negative biomarker and a resistance mechanism to trametinib/HCQ treatment, but can be overcome by combined palbociclib/HCQ treatment

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a recalcitrant disease responsible for ~43,000 deaths in the USA in 2017. Despite an advanced understanding of the genetics, biochemistry, and biology of pancreatic cancer, there is no effective pathway-targeted therapy for PDAC such that the standard-of-care treatment for most patients remains conventional cytotoxic chemotherapy. Although the clinical picture remains grim, progress has been made in understanding how alterations in tumor suppressors and proto-oncogenes contribute to PDAC initiation and progression. Whereas initiating mutations in KRAS promote the growth of premalignant pancreatic intraepithelial neoplasia, progression to cancer malignancy requires cooperating alterations of tumor suppressors such as TP53, CDKN2A, and/or SMAD4. Downstream of KRAS oncoproteins, the RAF®MEK®ERK MAP kinase signaling pathway plays a central role in the genesis of PDAC. However, to date, pharmacologic inhibition of this pathway has demonstrated little clinical benefit in PDAC patients. We have previously shown that combined inhibition of MEK1/2 and autophagy with chloroquine/hydroxychloroquine (CQ/HCQ) displays synergistic antiproliferative effects against PDAC cell lines in vitro, in xenografted patient-derived PDAC tumors, and treatment of a pancreatic cancer patient with trametinib/HCQ resulted in dramatic tumor regression. Unfortunately, this patient did go on to progress on trametinib/HCQ therapy and a second patient who was treated with the combination of trametinib and hydroxychloroquine was refractory to treatment. Strikingly, the only genetic difference between these two patients’ tumors at the start of trametinib/HCQ treatment was an MYC amplification, and our first patient demonstrated an acquired MYC amplification upon development of resistance. Here we demonstrate in preclinical models that overexpression of MYC in Mia-PaCa2 and PDX220 cells lines resulted in both refractory and resistant tumors. We have identified that the CDK4/6 inhibitor, palbociclib, also induces protective autophagy, and treating xenografted Mia-PaCa2 tumors overexpressing MYC with palbociclib/CQ resulted in striking tumor regression. We therefore tested the combination of palbociclib/CQ on PDX derived from our first patient upon resistance to trametinib/HCQ, which demonstrated regression and suppression of tumors when treated with palbociclib/CQ, but not palbociclib alone or trametinib/CQ. Finally, we treated our first patient with the combination of palbociclib/HCQ and saw a dramatic decline in CA19-9. These data suggest that MYC amplification may be a negative biomarker for response and also a resistance mechanism that can be overcome with combined inhibition of CDK4/6 and autophagy. Citation Format: Conan Kinsey, Dilru Silva, Mark Silvis, Sophia Schuman, Kajsa Affolter, Martin McMahon. Myc amplification is a negative biomarker and a resistance mechanism to trametinib/HCQ treatment, but can be overcome by combined palbociclib/HCQ treatment [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C30.

CRYAB inhibits migration and invasion of bladder cancer cells through the PI3K/AKT and ERK pathways.

Bladder cancer is a common malignancy characterized by a high recurrence rate and the development of drug resistance. Frequent mutations and gene expression alterations in the PI3K/AKT and mitogen-activated protein kinase-ERK pathways lead to deregulated cell growth and the acquisition of invasive properties, which facilitates tumour progression and confers resistance to chemotherapy. Therefore, identification of the underlying mechanisms that trigger the activation of these signalling pathways and control the invasive phenotype of tumour cells is of urgent need. We utilized publicly available gene expression databases (GEO and TCGA) and bioinformatics analysis to identify key gene expression changes in human bladder cancer . The key gene expression was detected using BC tissue microarrays. Cell proliferation, apoptosis, migration, invasion and related signalling pathways were analysed flowing transfection with key gene overexpression plasmids. The analysis revealed that inhibited expression of the alpha-crystallin B chain was a common feature in all analysed datasets. The decrease in alpha-crystallin B expression was further confirmed at the protein level using BC tissue microarrays. Overexpression of alpha-crystallin B in T24 and J82 BC cell lines resulted in significant inhibition of tumour cell migration and invasion, which was associated with a decrease in PI3K, AKT and ERK activation. Moreover, alpha-crystallin B overexpression increased the expression of E-cadherin, while reducing the expression of N-cadherin, which indicated suppression of the epithelial-mesenchymal transition. Overall, the results of our study suggested that alpha-crystallin B may function as a tumour-suppressive factor in bladder cancer.

Irisin Prevents Disuse-Induced Osteocyte Apoptosis.

Previous results showed that intermittently administered irisin improves bone mass in normal mice and prevents the development of disuse-induced osteoporosis and muscular atrophy in hindlimb-suspended mice, a murine model able to mimic the absence of mechanical loading. A recent study showed that irisin increases survival of osteocytes acting through integrin αV/β5 receptors. To better understand the action of irisin on these cells, we investigated the downstream signaling cascades in osteocyte-like cells (MLO-Y4) treated with recombinant irisin (rec-irisin) in vitro and we analyzed survival of osteocytes and caspase activation in cortical bone of osteoporotic mice treated with rec-irisin in vivo. Our results revealed that rec-irisin activated the MAP kinases Erk1 and Erk2 and increased the expression of the transcription factor Atf4 (2.5-fold, p < .05) through an Erk-dependent pathway in osteocytes. Some key genes expressed by MLO-Y4 cells were modulated by long-term irisin treatment, either continuously administered or given with intermittent short pulses. Interestingly, Sost mRNA was severely downregulated only upon intermittent irisin administration (10-fold, p < .001). Furthermore, rec-irisin upregulated Tfam mRNA (fourfold, p < .05) and Bcl2/Bax ratio (twofold, p < .05) in MLO-Y4 cells. By detecting caspase-9 and caspase-3, we also found that rec-irisin inhibited apoptosis induced by hydrogen peroxide and dexamethasone, respectively. In cortical bone of unloading C57BL6 mice treated with vehicle (unload-veh), irisin prevented disuse-induced reduction of viable osteocytes (+30% versus unload-veh, p < .05) and increase of empty lacunae (+110% versus unload-veh, p < .05), as well as caspase-9 (threefold, p < .05) and caspase-3 (twofold, p < .05) activations. Our findings revealed underlying mechanisms of irisin action on osteocytes, which increases their functions and exerts anti-apoptotic effects, confirming that mechanosensor cells of bone are sensitive to the exercise-mimetic myokine irisin. © 2019 American Society for Bone and Mineral Research.

Effects of a Tripeptide on Mitogen-Activated Protein Kinase and Glycogen Synthase Kinase Activation in a Cell Line Derived from the Foetal Hippocampus of a Trisomy 16 Mouse: an Animal Model of Down Syndrome.

Down syndrome (DS) is a developmental disorder that results from the trisomy of chromosome 21. DS patients show several abnormalities including cognitive deficits. Here, we show enhanced activation of the extracellular signal-regulated kinase (ERK), a kinase that critically regulates synaptic plasticity and memory, in a hippocampal cell line derived from trisomy 16 mouse foetus. In addition, these cells show enhanced activation of p38 mitogen-activated protein kinase (p38 MAPK). The hyper-activation of ERK and p38 MAPK is significantly reduced by a small peptide, Gly-Pro-Glu (GPE), derived from insulin-like growth factor-1. In addition, the trisomic cells show reduced level of inhibitory phosphorylation of glycogen synthase kinase-3β (GSK-3β), which is enhanced by GPE. Furthermore, the trisomic cells do not show ERK activation in response to KCl depolarization or forskolin treatment. Importantly, ERK activation by these stimuli is observed after GPE treatment of the cells. These results suggest that GPE may help reduce aberrant signalling in the trisomic neurons by affecting MAPK and GSK-3β activation.