PDRG1 promotes the proliferation and migration of GBM cells by the MEK/ERK/CD44 pathway

P53 and DNA damage‐regulated gene1 (PDRG1) is overexpressed in diverse carcinomas. Here, we discover that PDRG1 is overexpressed in glioblastoma multiforme (GBM). However, the clinical significance, biological role, and underlying molecular mechanisms of PDRG1 in GBM remain unclear. PDRG1 was aberrantly overexpressed in glioma, especially prevalent in GBM, and correlated with poor clinicopathologic features of glioma. The risk score, operational feature curve analysis, Kaplan‐Meier curve, and univariate and multivariate Cox regression analysis indicated that PDRG1 was an independent prognostic indicator and significantly correlates with disease progression of glioma. A prognostic nomogram was constructed to predict the survival risk of individual patients. The function and pathway enrichment analysis of PDRG1 in The Cancer Genome Atlas cohort was performed. PDRG1 knockdown significantly inhibited the migration and proliferation of GBM cells in vitro and in vivo. Transcriptome sequencing analysis of PDRG1 knockdown U‐118 MG(U118) cells indicated that biological regulation adhesion, growth and death, cell motility, cell adhesion molecular and proteoglycans in cancer were significantly enriched. Importantly, we found that the expression of adhesion molecule cluster of differentiation 44 (CD44) was regulated by PDRG1 in GBM. We found that PDRG1 promoted the migration and proliferation of GBM cells via the mitogen‐activated protein kinase kinase (MEK)/extracellular regulated protein kinase (ERK)/CD44 pathway. Our findings provide proof that PDRG1 upregulation predicts progression and poor prognosis in human gliomas, especially in isocitrate dehydrogenase (IDH) wt glioma patients. The study provides new evidence that PDRG1 regulates the expression of CD44 in GBM cells and might promote the migration and proliferation via the MEK/ERK/CD44pathway. PDRG1 might be a novel diagnostic indicator and promising therapeutic target for GBM.

N2L, a novel lipoic acid-niacin dimer, attenuates ferroptosis and decreases lipid peroxidation in HT22 cells

Ferroptosis, a new type of programmed cell death discovered in recent years, plays an important role in many neurodegenerative diseases. N2L is a novel lipoic acid-niacin dimer regulating lipid metabolism with multifunction, including antioxidant effect. It also exerts neuroprotective effects against glutamate- or β-amyloid (Aβ) -induced cell death. Because reactive oxygen species (ROS) play an essential role in ferroptosis, we hypothesize that N2L might protect cells from ferroptosis. Here, we investigated the protective effect of N2L and the underlying mechanism(s) under RAS-selective lethality 3 (RSL3) treatment in HT22 cells. RSL3 decreased the cell viability and induced excessive accumulation of ROS in HT22 cells. N2L pretreatment effectively protected HT22 cells against lipid peroxidation. What's more, N2L recovered glutathione peroxidase 4 (GPX4) expression and blocked the increase of Cyclooxygenase-2 (cox-2) and acyl-CoA synthetase long-chain family member 4 (ACSL4) protein expressions. Moreover, N2L also significantly prevented Ferritin Heavy Chain 1 (FTH1) from downregulation and maintained iron homeostasis. Finally, N2L pretreatment could decrease c-Jun N-terminal kinase (JNK) / extracellular regulated protein kinases (ERK) activation induced by RSL3. Taken together, our results showed that N2L could protect HT22 cells from RSL3-induced ferroptosis through decreasing lipid peroxidation and JNK/ERK activation. And N2L could be a ferroptosis inhibitor for the therapy of ferroptosis-related diseases, such as Alzheimer's disease.

Gold nanoparticles synergize with bacterial lipopolysaccharide to enhance class A scavenger receptor dependent particle uptake in neutrophils and augment neutrophil extracellular traps formation

Gold nanoparticles (AuNPs) are extensively utilized in biomedical fields. However, their potential interaction with host cells has not been comprehensively elucidated. In this study, we demonstrated a size-dependent effect of AuNPs to synergize with bacterial lipopolysaccharide (LPS) in promoting neutrophil extracellular traps (NETs) release in human peripheral neutrophils. Mechanistically, LPS was more efficient to contact with 10 nm AuNPs and promote their uptake in neutrophils compared to 40 and 100 nm AuNPs, leading to a synergistic upregulation of class A scavenger receptor (SRA) which mediated AuNPs uptake and triggered activation of extracellular regulated protein kinase (ERK) and p38. Blocking SRA or inhibiting ERK and p38 activation remarkably abrogated the effect of AuNPs and LPS to induce NETs formation. Further experiments demonstrated that AuNPs and LPS augmented the production of cytosolic reactive oxygen species (ROS) in p38 and ERK dependent manner, through upregulating and activating NADPH oxidase 2 (NOX2). Accordingly, scavenging of ROS or inhibiting the NOX2 dampened NETs release induced by combined AuNPs and LPS treatment. AuNPs and LPS also synergized to upregulate reactive oxygen species modulator 1 (ROMO1) via activating ERK, thereby increasing mitochondrial ROS generation and promoting the release of NETs. In summary, we provide new evidences about the synergy of AuNPs and LPS to augment cellular responses in neutrophils, which implicates the need to consider the amplifying effect by pathogenic stimuli when utilizing nanomaterials in infectious or inflammatory conditions.

[Transforming growth factor-β1 small interfering RNA regulates platelet-derived growth factor and phosphorylated extracellular regulated protein kinase in rats with hepatic fibrosis: an experimental study]

Objective: To investigate the impact of transforming growth factor-β1 (TGF-β1) silencing by small interfering RNA (siRNA) on the expression of platelet-derived growth factor-β (PDGF-BB) and its receptor (PDGF-βR) in rats with hepatic fibrosis. Methods: A total of 40 male Sprague-Dawley rats were randomly divided into normal control group, model group, TGF-β1 siRNA treatment group, and negative control group. All rats except those in the normal control group were given subcutaneous injection of 40% carbon tetrachloride to establish a rat model of hepatic fibrosis. The rats in the negative control group and the TGF-β1 siRNA treatment group were given tail vein injection of negative control plasmid or TGF-β1 siRNA plasmid twice a week at a dose of 0.25 mg/kg, and those in the normal control group and the model group were given the injection of sterile isotonic saline twice a week. The rats were sacrificed after 12 weeks and liver tissue samples were collected. Real-time PCR, immunohistochemistry, and Western blot were used to measure the expression of PDGF-BB, PDGF-βR, and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) in liver tissue. A one-way analysis of variance, the q test, and the Kruskal-Wallis test were used for statistical analysis based on data type. Results: Compared with the model group and the negative control group, the TGF-β1 siRNA treatment group had significantly inhibited mRNA and protein expression of PDGF-BB and PDGF-βR (F = 24.785 and 22.92, P < 0.01), as well as significantly inhibited expression of p-ERK1/2 (P < 0.05). Conclusion: Targeted TGF-β1 siRNA can effectively downregulate the expression of PDGF-BB, PDGF-βR, and p-ERK1/2 in liver tissue and thus help to improve hepatic fibrosis.

Hematopoietic stem/progenitor cells directly contribute to arteriosclerotic progression via integrin β2

Recent studies described the association between hematopoietic stem/progenitor cell (HSPC) expansion in the bone marrow (BM), leukocytosis in the peripheral blood, and accelerated atherosclerosis. We hypothesized that circulating HSPC may home to inflamed vessels, where they might contribute to inflammation and neointima formation. We demonstrated that Lin⁻ Sca-1⁺ cKit⁺ (LSK cells) in BM and peripheral blood of LDLr^−/− mice on high fat diet expressed significantly more integrin β₂, which was responsible for LSK cell adhesion and migration toward ICAM-1 in vitro, and homing to injured arteries in vivo, all of which were blocked with an anti-CD18 blocking antibody. When homed LSK cells were isolated from ligated artery and injected to irradiated recipients, they resulted in BM reconstitution. Injection of CD18^+/+ LSK cells to immunodeficient Balb/C Rag2⁻ γC^−/− recipients resulted in more severe inflammation and reinforced neointima formation in the ligated carotid artery, compared to mice injected with PBS and CD18^−/− LSK cells. Hypercholesterolemia stimulated ERK phosphorylation (pERK) in LSK cells of LDLr^−/− mice in vivo. Blockade of pERK reduced ARF1 expression, leading to decreased integrin β₂ function on HSPC. In addition, integrin β₂ function could be regulated via ERK-independent LRP1 pathway. Integrin β₂ expression on HSPC is regulated by hypercholesterolemia, specifically LDL, in pERK-dependent and -independent manners, leading to increased homing and localization of HSPC to injured arteries, which is highly correlated with arteriosclerosis. Stem Cells2015;33:1230–1240

Atorvastatin treatment improves the effects of mesenchymal stem cell transplantation on acute myocardial infarction: the role of the RhoA/ROCK/ERK pathway

BACKGROUND

Statins protect mesenchymal stem cells (MSCs) against the harsh microenvironment and improve the efficacy of MSC transplantation after acute myocardial infarction (AMI); however, the mechanism remains uncertain. Furthermore, the transdifferentiation potential of MSCs in the post-infarct heart remains highly controversial. The RhoA/Rho-associated coiled-coil-forming kinase (ROCK) pathway participates in many aspects of the damaged heart after AMI and related to the "pleiotropic" effects of statins. This study aimed to explore whether atorvastatin (ATV) facilitates the survival and therapeutic efficacy of MSCs via the inhibition of RhoA/ROCK pathway and subsequently its downstream molecular extracellular regulated protein kinase (ERK1/2), and to investigate the transdifferentiation potential of MSCs in vivo.

METHODS AND RESULTS

Female rats received myocardial injections of male rat MSCs 30 min after AMI. Four weeks after AMI, ATV combined with MSC treatment resulted in improved cardiac function and reduced infarct area. ATV facilitated the MSC survival, as revealed by the increased expression of Y chromosomal genes and the increased number of Y chromosome-positive cells; however, no transdifferentiation markers were observed. ATV inhibited the production of inflammatory cytokines both in vitro and vivo, accompanied by suppression of ROCK and ERK activities. Geranylgeranyl pyrophosphate (GGPP) abrogated the effects of ATV in the H9c2 cells under hypoxia/serum deprivation (H/SD), while the ROCK inhibitor fasudil mimicked the benefits of ATV after AMI.

CONCLUSIONS

ATV improves the post-infarct microenvironment via RhoA/ROCK/ERK inhibition and thus facilitates the survival and efficacy of implanted MSCs. Transdifferentiation may be not responsible for the cardiac benefits that follow MSC transplantation.

Clinical significance of expression of Ras protein activator like 1 and extracellular regulated protein kinase in gastric cancer

AIM: To investigate the expression of Ras protein activator like 1 (RASAL1) and extracellular regulated protein kinase (ERK) in gastric cancer and to analyze their association with clinicopathological features of gastric cancer.

METHODS: The expression of RASAL1, ERK and phosphorylated ERK (p-ERK) was detected by immunohistochemistry in 60 gastric cancer tissue specimens and matched tumor-adjacent tissue specimens. The association of RASAL1 and ERK expression with clinicopathologic characteristics of gastric cancer was then analyzed.

RESULTS: RASAL1 expression was weak or undetectable in gastric cancer but strong in tumor-adjacent tissue (mean rank score: 35.84 vs 85.16, P < 0.01). No significant difference was observed in ERK expression between gastric cancer and tumor-adjacent tissue (mean rank score: 60.68 vs 60.33, P > 0.05). The expression level of p-ERK in gastric cancer was significantly higher than that in tumor-adjacent tissue (mean rank score: 84.93 vs 36.07, P < 0.0001). Besides, decreased expression of RASAL1 and over-activation of ERK were significantly correlated with tumor size, stage, depth of invasion, grade and lymph node metastasis (all P < 0.05).

CONCLUSION: Low expression of RASAL1 and high expression of p-ERK may be involved in the development and progression of gastric cancer. RASAL1 promotes gastric cancer occurrence and development possibly by regulating the activation of ERK.