E-cigarettes Induce Dysregulation of Autophagy Leading to Endothelial Dysfunction in Pulmonary Arterial Hypertension.

Given the increasing popularity of electronic cigarettes (e-cigs), it is imperative to evaluate the potential health risks of e-cigs, especially in users with preexisting health concerns such as pulmonary arterial hypertension (PAH). The aim of the present study was to investigate whether differential susceptibility exists between healthy and patients with PAH to e-cig exposure and the molecular mechanisms contributing to it. Patient-specific induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) from healthy individuals and patients with PAH were used to investigate whether e-cig contributes to the pathophysiology of PAH and affects EC homeostasis in PAH. Our results showed that PAH iPSC-ECs showed a greater amount of damage than healthy iPSC-ECs upon e-cig exposure. Transcriptomic analyses revealed that differential expression of Akt3 may be responsible for increased autophagic flux impairment in PAH iPSC-ECs, which underlies increased susceptibility upon e-cig exposure. Moreover, knockdown of Akt3 in healthy iPSC-ECs significantly induced autophagic flux impairment and endothelial dysfunction, which further increased with e-cig treatment, thus mimicking the PAH cell phenotype after e-cig exposure. In addition, functional disruption of mTORC2 by knocking down Rictor in PAH iPSC-ECs caused autophagic flux impairment, which was mediated by downregulation of Akt3. Finally, pharmacological induction of autophagy via direct inhibition of mTORC1 and indirect activation of mTORC2 with rapamycin reverses e-cig-induced decreased Akt3 expression, endothelial dysfunction, autophagic flux impairment, and decreased cell viability, and migration in PAH iPSC-ECs. Taken together, these data suggest a potential link between autophagy and Akt3-mediated increased susceptibility to e-cig in PAH.

AI-Driven Deep Learning Techniques in Protein Structure Prediction.

Protein structure prediction is important for understanding their function and behavior. This review study presents a comprehensive review of the computational models used in predicting protein structure. It covers the progression from established protein modeling to state-of-the-art artificial intelligence (AI) frameworks. The paper will start with a brief introduction to protein structures, protein modeling, and AI. The section on established protein modeling will discuss homology modeling, ab initio modeling, and threading. The next section is deep learning-based models. It introduces some state-of-the-art AI models, such as AlphaFold (AlphaFold, AlphaFold2, AlphaFold3), RoseTTAFold, ProteinBERT, etc. This section also discusses how AI techniques have been integrated into established frameworks like Swiss-Model, Rosetta, and I-TASSER. The model performance is compared using the rankings of CASP14 (Critical Assessment of Structure Prediction) and CASP15. CASP16 is ongoing, and its results are not included in this review. Continuous Automated Model EvaluatiOn (CAMEO) complements the biennial CASP experiment. Template modeling score (TM-score), global distance test total score (GDT_TS), and Local Distance Difference Test (lDDT) score are discussed too. This paper then acknowledges the ongoing difficulties in predicting protein structure and emphasizes the necessity of additional searches like dynamic protein behavior, conformational changes, and protein-protein interactions. In the application section, this paper introduces some applications in various fields like drug design, industry, education, and novel protein development. In summary, this paper provides a comprehensive overview of the latest advancements in established protein modeling and deep learning-based models for protein structure predictions. It emphasizes the significant advancements achieved by AI and identifies potential areas for further investigation.

A Comparative Analysis of SARS-CoV-2 Variants of Concern (VOC) Spike Proteins Interacting with hACE2 Enzyme.

In late 2019, the emergence of a novel coronavirus led to its identification as SARS-CoV-2, precipitating the onset of the COVID-19 pandemic. Many experimental and computational studies were performed on SARS-CoV-2 to understand its behavior and patterns. In this research, Molecular Dynamic (MD) simulation is utilized to compare the behaviors of SARS-CoV-2 and its Variants of Concern (VOC)-Alpha, Beta, Gamma, Delta, and Omicron-with the hACE2 protein. Protein structures from the Protein Data Bank (PDB) were aligned and trimmed for consistency using Chimera, focusing on the receptor-binding domain (RBD) responsible for ACE2 interaction. MD simulations were performed using Visual Molecular Dynamics (VMD) and Nanoscale Molecular Dynamics (NAMD2), and salt bridges and hydrogen bond data were extracted from the results of these simulations. The data extracted from the last 5 ns of the 10 ns simulations were visualized, providing insights into the comparative stability of each variant's interaction with ACE2. Moreover, electrostatics and hydrophobic protein surfaces were calculated, visualized, and analyzed. Our comprehensive computational results are helpful for drug discovery and future vaccine designs as they provide information regarding the vital amino acids in protein-protein interactions (PPIs). Our analysis reveals that the Original and Omicron variants are the two most structurally similar proteins. The Gamma variant forms the strongest interaction with hACE2 through hydrogen bonds, while Alpha and Delta form the most stable salt bridges; the Omicron is dominated by positive potential in the binding site, which makes it easy to attract the hACE2 receptor; meanwhile, the Original, Beta, Delta, and Omicron variants show varying levels of interaction stability through both hydrogen bonds and salt bridges, indicating that targeted therapeutic agents can disrupt these critical interactions to prevent SARS-CoV-2 infection.

Endothelial PHD2 deficiency induces nitrative stress via suppression of caveolin-1 in pulmonary hypertension.

BACKGROUND: Nitrative stress is a characteristic feature of the pathology of human pulmonary arterial hypertension. However, the role of nitrative stress in the pathogenesis of obliterative vascular remodelling and severe pulmonary arterial hypertension remains largely unclear. METHOD: Our recently identified novel mouse model (Egln1Tie2Cre, Egln1 encoding prolyl hydroxylase 2 (PHD2)) has obliterative vascular remodelling and right heart failure, making it an excellent model to use in this study to examine the role of nitrative stress in obliterative vascular remodelling. RESULTS: Nitrative stress was markedly elevated whereas endothelial caveolin-1 (Cav1) expression was suppressed in the lungs of Egln1Tie2Cre mice. Treatment with a superoxide dismutase mimetic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride or endothelial Nos3 knockdown using endothelial cell-targeted nanoparticle delivery of CRISPR-Cas9/guide RNA plasmid DNA inhibited obliterative pulmonary vascular remodelling and attenuated severe pulmonary hypertension in Egln1Tie2Cre mice. Genetic restoration of Cav1 expression in Egln1Tie2Cre mice normalised nitrative stress, reduced pulmonary hypertension and improved right heart function. CONCLUSION: These data suggest that suppression of Cav1 expression secondary to PHD2 deficiency augments nitrative stress through endothelial nitric oxide synthase activation, which contributes to obliterative vascular remodelling and severe pulmonary hypertension. Thus, a reactive oxygen/nitrogen species scavenger might have therapeutic potential for the inhibition of obliterative vascular remodelling and severe pulmonary arterial hypertension.

Endothelial cells in the pathogenesis of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a devastating disease that involves pulmonary vasoconstriction, small vessel obliteration, large vessel thickening and obstruction, and development of plexiform lesions. PAH vasculopathy leads to progressive increases in pulmonary vascular resistance, right heart failure and, ultimately, premature death. Besides other cell types that are known to be involved in PAH pathogenesis (e.g. smooth muscle cells, fibroblasts and leukocytes), recent studies have demonstrated that endothelial cells (ECs) have a crucial role in the initiation and progression of PAH. The EC-specific role in PAH is multi-faceted and affects numerous pathophysiological processes, including vasoconstriction, inflammation, coagulation, metabolism and oxidative/nitrative stress, as well as cell viability, growth and differentiation. In this review, we describe how EC dysfunction and cell signalling regulate the pathogenesis of PAH. We also highlight areas of research that warrant attention in future studies, and discuss potential molecular signalling pathways in ECs that could be targeted therapeutically in the prevention and treatment of PAH.

Endothelial Autocrine Signaling through CXCL12/CXCR4/FoxM1 Axis Contributes to Severe Pulmonary Arterial Hypertension.

Endothelial autocrine signaling is essential to maintain vascular homeostasis. There is limited information about the role of endothelial autocrine signaling in regulating severe pulmonary vascular remodeling during the onset of pulmonary arterial hypertension (PAH). In this study, we employed the first severe pulmonary hypertension (PH) mouse model, Egln1Tie2Cre (Tie2Cre-mediated disruption of Egln1) mice, to identify the novel autocrine signaling mediating the pulmonary vascular endothelial cell (PVEC) proliferation and the pathogenesis of PAH. PVECs isolated from Egln1Tie2Cre lung expressed upregulation of many growth factors or angiocrine factors such as CXCL12, and exhibited pro-proliferative phenotype coincident with the upregulation of proliferation-specific transcriptional factor FoxM1. Treatment of CXCL12 on PVECs increased FoxM1 expression, which was blocked by CXCL12 receptor CXCR4 antagonist AMD3100 in cultured human PVECs. The endothelial specific deletion of Cxcl12(Egln1/Cxcl12Tie2Cre) or AMD3100 treatment in Egln1Tie2Cre mice downregulated FoxM1 expression in vivo. We then generated and characterized a novel mouse model with endothelial specific FoxM1 deletion in Egln1Tie2Cre mice (Egln1/Foxm1Tie2Cre), and found that endothelial FoxM1 deletion reduced pulmonary vascular remodeling and right ventricular systolic pressure. Together, our study identified a novel mechanism of endothelial autocrine signaling in regulating PVEC proliferation and pulmonary vascular remodeling in PAH.

A mutation found in esophageal cancer alters integrin ß4 mRNA splicing.

Integrin ß4 (CD104, mRNA: ITGß4) contributes to anchoring cells to the extracellular matrix and is regulated in many cancer types where it contributes to tumor progression. One splice variant, integrin ß4E, is poorly characterized. We extracted several mutations from tumor samples within ITGB4 near the splice site that controls ITGß4E production, and computational analysis predicted six of these would alter splicing to alter ITGß4E abundance. One of these mutations, from an esophageal squamous cell carcinoma sample, was predicted to increase splicing toward ITGß4E. We verified this effect using a minigene, and observed that integrin ß4E slows esophageal squamous cell migration while other variants enhance migration, demonstrating that integrin ß4E regulation through mutations may contribute to esophageal squamous cell tumorigenesis.

Endothelial and Smooth Muscle Cell Interaction via FoxM1 Signaling Mediates Vascular Remodeling and Pulmonary Hypertension.

RATIONALE: Angioproliferative vasculopathy is a hallmark of pulmonary arterial hypertension (PAH). However, little is known about how endothelial cell (EC) and smooth muscle cell (SMC) crosstalk regulates the angioproliferative vascular remodeling. OBJECTIVES: To investigate the role of EC and SMC interaction and underlying signaling pathways in pulmonary hypertension (PH) development. METHODS: SMC-specific Foxm1 (forkhead box M1) or Cxcr4 knockout mice, EC-specific Foxm1 or Egln1 knockout mice, and EC-specific Egln1/Cxcl12 double knockout mice were used to assess the role of FoxM1 on SMC proliferation and PH. Lung tissues and cells from patients with PAH were used to validate clinical relevance. FoxM1 inhibitor thiostrepton was used in Sugen 5416/hypoxia- and monocrotaline-challenged rats. MEASUREMENTS AND MAIN RESULTS: FoxM1 expression was markedly upregulated in lungs and pulmonary arterial SMCs of patients with idiopathic PAH and four discrete PH rodent models. Mice with SMC- (but not EC-) specific deletion of Foxm1 were protected from hypoxia- or Sugen 5416/hypoxia-induced PH. The upregulation of FoxM1 in SMCs induced by multiple EC-derived factors (PDGF-B, CXCL12, ET-1, and MIF) mediated SMC proliferation. Genetic deletion of endothelial Cxcl12 in Egln1Tie2Cre mice or loss of its cognate receptor Cxcr4 in SMCs in hypoxia-treated mice inhibited FoxM1 expression, SMC proliferation, and PH. Accordingly, pharmacologic inhibition of FoxM1 inhibited severe PH in both Sugen 5416/hypoxia and monocrotaline-challenged rats. CONCLUSIONS: Multiple factors derived from dysfunctional ECs induced FoxM1 expression in SMCs and activated FoxM1-dependent SMC proliferation, which contributes to pulmonary vascular remodeling and PH. Thus, targeting FoxM1 signaling represents a novel strategy for treatment of idiopathic PAH.

Therapeutic Targeting of Vascular Remodeling and Right Heart Failure in Pulmonary Arterial Hypertension with a HIF-2α Inhibitor.

RATIONALE: Pulmonary arterial hypertension (PAH) is a devastating disease characterized by progressive vasoconstriction and obliterative vascular remodeling that leads to right heart failure (RHF) and death. Current therapies do not target vascular remodeling and RHF, and result in only modest improvement of morbidity and mortality. OBJECTIVES: To determine whether targeting HIF-2α (hypoxia-inducible factor-2α) with a HIF-2α-selective inhibitor could reverse PAH and RHF in various rodent PAH models. METHODS: HIF-2α and its downstream genes were evaluated in lung samples and pulmonary arterial endothelial cells and smooth muscle cells from patients with idiopathic PAH as well as various rodent PAH models. A HIF-2α-selective inhibitor was used in human lung microvascular endothelial cells and in Egln1Tie2Cre mice, and in Sugen 5416/hypoxia- or monocrotaline-exposed rats. MEASUREMENTS AND MAIN RESULTS: Upregulation of HIF-2α and its target genes was observed in lung tissues and isolated pulmonary arterial endothelial cells from patients with idiopathic PAH and three distinct rodent PAH models. Pharmacological inhibition of HIF-2α by the HIF-2α translation inhibitor C76 (compound 76) reduced right ventricular systolic pressure and right ventricular hypertrophy and inhibited RHF and fibrosis as well as obliterative pulmonary vascular remodeling in Egln1Tie2Cre mice and Sugen 5416/hypoxia PAH rats. Treatment of monocrotaline-exposed PAH rats with C76 also reversed right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling; prevented RHF; and promoted survival. CONCLUSIONS: These findings demonstrate that pharmacological inhibition of HIF-2α is a promising novel therapeutic strategy for the treatment of severe vascular remodeling and right heart failure in patients with PAH.

Prolyl-4 Hydroxylase 2 (PHD2) Deficiency in Endothelial Cells and Hematopoietic Cells Induces Obliterative Vascular Remodeling and Severe Pulmonary Arterial Hypertension in Mice and Humans Through Hypoxia-Inducible Factor-2α.

BACKGROUND: Vascular occlusion and complex plexiform lesions are hallmarks of the pathology of severe pulmonary arterial hypertension (PAH) in patients. However, the mechanisms of obliterative vascular remodeling remain elusive; hence, current therapies have not targeted the fundamental disease-modifying mechanisms and result in only modest improvement in morbidity and mortality. METHODS AND RESULTS: Mice with Tie2Cre-mediated disruption of Egln1 (encoding prolyl-4 hydroxylase 2 [PHD2]; Egln1(Tie2)) in endothelial cells and hematopoietic cells exhibited spontaneous severe PAH with extensive pulmonary vascular remodeling, including vascular occlusion and plexiform-like lesions, resembling the hallmarks of the pathology of clinical PAH. As seen in patients with idiopathic PAH, Egln1(Tie2) mice exhibited unprecedented right ventricular hypertrophy and failure and progressive mortality. Consistently, PHD2 expression was diminished in lung endothelial cells of obliterated pulmonary vessels in patients with idiopathic PAH. Genetic deletions of both Egln1 and Hif1a or Egln1 and Hif2a identified hypoxia-inducible factor-2α as the critical mediator of the severe PAH seen in Egln1(Tie2) mice. We also observed altered expression of many pulmonary hypertension-causing genes in Egln1(Tie2) lungs, which was normalized in Egln1(Tie2)/Hif2a(Tie2) lungs. PHD2-deficient endothelial cells promoted smooth muscle cell proliferation in part through hypoxia-inducible factor-2α-activated CXCL12 expression. Genetic deletion of Cxcl12 attenuated PAH in Egln1(Tie2) mice. CONCLUSIONS: These studies defined an unexpected role of PHD2 deficiency in the mechanisms of severe PAH and identified the first genetically modified mouse model with obliterative vascular remodeling and pathophysiology recapitulating clinical PAH. Thus, targeting PHD2/hypoxia-inducible factor-2α signaling is a promising strategy to reverse vascular remodeling for treatment of severe PAH.

Endothelial p110γPI3K Mediates Endothelial Regeneration and Vascular Repair After Inflammatory Vascular Injury.

BACKGROUND: The integrity of endothelial monolayer is a sine qua non for vascular homeostasis and maintenance of tissue-fluid balance. However, little is known about the signaling pathways regulating regeneration of the endothelial barrier after inflammatory vascular injury. METHODS AND RESULTS: Using genetic and pharmacological approaches, we demonstrated that endothelial regeneration selectively requires activation of p110γPI3K signaling, which thereby mediates the expression of the endothelial reparative transcription factor Forkhead box M1 (FoxM1). We observed that FoxM1 induction in the pulmonary vasculature was inhibited in mice treated with a p110γ-selective inhibitor and in Pik3cg(-/-) mice after lipopolysaccharide challenge. Pik3cg(-/-) mice exhibited persistent lung inflammation induced by sepsis and sustained increase in vascular permeability. Restoration of expression of either p110γ or FoxM1 in pulmonary endothelial cells of Pik3cg(-/-) mice restored endothelial regeneration and normalized the defective vascular repair program. We also observed diminished expression of p110γ in pulmonary vascular endothelial cells of patients with acute respiratory distress syndrome, suggesting that impaired p110γ-FoxM1 vascular repair signaling pathway is a critical factor in persistent leaky lung microvessels and edema formation in the disease. CONCLUSIONS: We identify p110γ as the critical mediator of endothelial regeneration and vascular repair after sepsis-induced inflammatory injury. Thus, activation of p110γ-FoxM1 endothelial regeneration may represent a novel strategy for the treatment of inflammatory vascular diseases.

Plasminogen kringle 5 induces endothelial cell apoptosis by triggering a voltage-dependent anion channel 1 (VDAC1) positive feedback loop.

Human plasminogen kringle 5 (K5) is known to display its potent anti-angiogenesis effect through inducing endothelial cell (EC) apoptosis, and the voltage-dependent anion channel 1 (VDAC1) has been identified as a receptor of K5. However, the exact role and underlying mechanisms of VDAC1 in K5-induced EC apoptosis remain elusive. In the current study, we showed that K5 increased the protein level of VDAC1, which initiated the mitochondrial apoptosis pathway of ECs. Our findings also showed that K5 inhibited the ubiquitin-dependent degradation of VDAC1 by promoting the phosphorylation of VDAC1, possibly at Ser-12 and Thr-107. The phosphorylated VDAC1 was attenuated by the AKT agonist, glycogen synthase kinase (GSK) 3ß inhibitor, and siRNA, suggesting that K5 increased VDAC1 phosphorylation via the AKT-GSK3ß pathway. Furthermore, K5 promoted cell surface translocation of VDAC1, and binding between K5 and VDAC1 was observed on the plasma membrane. HKI protein blocked the impact of K5 on the AKT-GSK3ß pathway by competitively inhibiting the interaction of K5 and cell surface VDAC1. Moreover, K5-induced EC apoptosis was suppressed by VDAC1 antibody. These data show for the first time that K5-induced EC apoptosis is mediated by the positive feedback loop of "VDAC1-AKT-GSK3ß-VDAC1," which may provide new perspectives on the mechanisms of K5-induced apoptosis.

Pigment epithelial-derived factor (PEDF)-triggered lung cancer cell apoptosis relies on p53 protein-driven Fas ligand (Fas-L) up-regulation and Fas protein cell surface translocation.

Pigment epithelium-derived factor (PEDF), a potent antiangiogenesis agent, has recently attracted attention for targeting tumor cells in several types of tumors. However, less is known about the apoptosis-inducing effect of PEDF on human lung cancer cells and the underlying molecular events. Here we report that PEDF has a growth-suppressive and proapoptotic effect on lung cancer xenografts. Accordingly, in vitro, PEDF apparently induced apoptosis in A549 and Calu-3 cells, predominantly via the Fas-L/Fas death signaling pathway. Interestingly, A549 and Calu-3 cells are insensitive to the Fas-L/Fas apoptosis pathway because of the low level of cell surface Fas. Our results revealed that, in addition to the enhancement of Fas-L expression, PEDF increased the sensitivity of A549 and Calu-3 cells to Fas-L-mediated apoptosis by triggering the translocation of Fas protein to the plasma membrane in a p53- and FAP-1-dependent manner. Similarly, the up-regulation of Fas-L by PEDF was also mediated by p53. Furthermore, peroxisome proliferator-activated receptor γ was determined to be the upstream regulator of p53. Together, these findings uncover a novel mechanism of tumor cell apoptosis induced by PEDF and provide a potential therapeutic strategy for tumors that are insensitive to Fas-L/Fas-dependent apoptosis because of a low level of cell surface Fas.

Endothelial FoxM1 mediates bone marrow progenitor cell-induced vascular repair and resolution of inflammation following inflammatory lung injury.

Adult stem cell treatment is a potential novel therapeutic approach for acute respiratory distress syndrome. Given the extremely low rate of cell engraftment, it is believed that these cells exert their beneficial effects via paracrine mechanisms. However, the endogenous mediator(s) in the pulmonary vasculature remains unclear. Using the mouse model with endothelial cell (EC)-restricted disruption of FoxM1 (FoxM1 CKO), here we show that endothelial expression of the reparative transcriptional factor FoxM1 is required for the protective effects of bone marrow progenitor cells (BMPC) against LPS-induced inflammatory lung injury and mortality. BMPC treatment resulted in rapid induction of FoxM1 expression in wild type (WT) but not FoxM1 CKO lungs. BMPC-induced inhibition of lung vascular injury, resolution of lung inflammation, and survival, as seen in WT mice, were abrogated in FoxM1 CKO mice following LPS challenge. Mechanistically, BMPC treatment failed to induce lung EC proliferation in FoxM1 CKO mice, which was associated with impaired expression of FoxM1 target genes essential for cell cycle progression. We also observed that BMPC treatment enhanced endothelial barrier function in WT but not in FoxM1-deficient EC monolayers. Restoration of ß-catenin expression in FoxM1-deficient ECs normalized endothelial barrier enhancement in response to BMPC treatment. These data demonstrate the requisite role of endothelial FoxM1 in the mechanism of BMPC-induced vascular repair to restore vascular integrity and accelerate resolution of inflammation, thereby promoting survival following inflammatory lung injury.

Loss of caveolin-1 and adiponectin induces severe inflammatory lung injury following LPS challenge through excessive oxidative/nitrative stress.

Excessive reactive oxygen/nitrogen species have been associated with the onset, progression, and outcome of sepsis, both in preclinical and clinical studies. However, the signaling pathways regulating oxidative/nitrative stress in the pathogenesis of sepsis-induced acute lung injury and acute respiratory distress syndrome are not fully understood. Employing the novel mouse model with genetic deletions of both caveolin-1 (Cav1) and adiponectin (ADPN) [double knockout (DKO) mice], we have demonstrated the critical role of Cav1 and ADPN signaling cross talk in regulating oxidative/nitrative stress and resulting inflammatory lung injury following LPS challenge. In contrast to the inhibited inflammatory lung injury in Cav1(-/-) mice, we observed severe lung inflammation and markedly increased lung vascular permeability in DKO mice in response to LPS challenge. Accordingly, the DKO mice exhibited an 80% mortality rate following a sublethal dose of LPS challenge. At basal state, loss of Cav1 and ADPN resulted in a drastic increase of oxidative stress and resultant nitrative stress in DKO lungs. Scavenging of superoxide by pretreating the DKO mice with MnTMPYP (a superoxide dismutase mimetic) restored the inflammatory responses to LPS challenge including reduced lung myeloperoxidase activity and vascular permeability. Thus oxidative/nitrative stress collectively modulated by Cav1 and ADPN signalings is a critical determinant of inflammatory lung injury in response to LPS challenge.

Pigment epithelium-derived factor (PEDF) inhibits breast cancer metastasis by down-regulating fibronectin.

Pigment epithelium-derived factor (PEDF) plays an important role in the tumor growth and metastasis inhibition. It has been reported that PEDF expression is significantly reduced in breast cancer, and associated with disease progression and poor patient outcome. However, the exact mechanism of PEDF on breast cancer metastasis including liver and lung metastasis remains unclear. The present study aims to reveal the impact of PEDF on breast cancer. The orthotopic tumor mice model inoculated by MDA-MB-231 cells stably expressing PEDF or control cells was used to assess liver and lung metastasis of breast cancer. In vitro, migration and invasion experiments were used to detect the metastatic abilities of MDA-MB-231 and SKBR3 breast cancer cells with or without overexpression of PEDF. The metastatic-related molecules including EMT makers, fibronectin, and p-AKT and p-ERK were detected by qRT-PCR, Western blot, and Fluorescent immunocytochemistry. PEDF significantly inhibited breast cancer growth and metastasis in vivo and in vitro. Mechanically, PEDF inhibited breast cancer cell migration and invasion by down-regulating fibronectin and subsequent MMP2/MMP9 reduction via p-ERK and p-AKT signaling pathways. However, PEDF had no effect on EMT conversion in the breast cancer cells which was usually involved in cancer metastasis. Furthermore, the study showed that laminin receptor mediated the down-regulation of fibronectin by PEDF. These results reported for the first time that PEDF inhibited breast cancer metastasis by down-regulating fibronectin via laminin receptor/AKT/ERK pathway. Our findings demonstrated PEDF as a dual effector in limiting breast cancer growth and metastasis and highlighted a new avenue to block breast cancer progression.