Platelet-derived growth factor signaling in pericytes promotes hypothalamic inflammation and obesity.

BACKGROUND: Pericytes are a vital component of the blood-brain barrier, and their involvement in acute inflammation was recently suggested. However, it remains unclear whether pericytes contribute to hypothalamic chronic inflammation and energy metabolism in obesity. The present study investigated the impact of pericytes on the pathophysiology of obesity by focusing on platelet-derived growth factor (PDGF) signaling, which regulates pericyte functions. METHODS: Tamoxifen-inducible systemic conditional PDGF receptor ß knockout mice (Pdgfrb∆SYS-KO) and Calcium/calmodulin-dependent protein kinase type IIa (CaMKIIa)-positive neuron-specific PDGF receptor ß knockout mice (Pdgfrb∆CaMKII-KO) were fed a high-fat diet, and metabolic phenotypes before and 3 to 4 weeks after dietary loading were examined. Intracellular energy metabolism and relevant signal transduction in lipopolysaccharide- and/or platelet-derived growth factor-BB (PDGF-BB)-stimulated human brain pericytes (HBPCs) were assessed by the Seahorse XFe24 Analyzer and Western blotting. The pericyte secretome in conditioned medium from HBPCs was studied using cytokine array kit, and its impact on polarization was examined in bone marrow-derived macrophages (BMDMs), which are microglia-like cells. RESULTS: Energy consumption increased and body weight gain decreased after high-fat diet loading in Pdgfrb∆SYS-KO mice. Cellular oncogene fos (cFos) expression increased in proopiomelanocortin (POMC) neurons, whereas microglial numbers and inflammatory gene expression decreased in the hypothalamus of Pdgfrb∆SYS-KO mice. No significant changes were observed in Pdgfrb∆CaMKII-KO mice. In HBPCs, a co-stimulation with lipopolysaccharide and PDGF-BB shifted intracellular metabolism towards glycolysis, activated mitogen-activated protein kinase (MAPK), and modulated the secretome to the inflammatory phenotype. Consequently, the secretome showed an increase in various proinflammatory chemokines and growth factors including Epithelial-derived neutrophil-activating peptide 78 (C-X-C motif chemokine ligand (CXCL)5), Thymus and activation-regulated chemokine (C-C motif chemokine (CCL)17), Monocyte chemoattractant protein 1 (CCL2), and Growth-regulated oncogene α (CXCL1). Furthermore, conditioned medium from HBPCs stimulated the inflammatory priming of BMDMs, and this change was abolished by the C-X-C motif chemokine receptor (CXCR) inhibitor. Consistently, mRNA expression of CXCL5 was elevated by lipopolysaccharide and PDGF-BB treatment in HBPCs, and the expression was significantly lower in the hypothalamus of Pdgfrb∆SYS-KO mice than in control Pdgfrbflox/flox mice (FL) following 4 weeks of HFD feeding. CONCLUSIONS: PDGF receptor ß signaling in hypothalamic pericytes promotes polarization of macrophages by changing their secretome and contributes to the progression of obesity.

KLF7 promotes colon adenocarcinoma progression through the PDGFB signaling pathway.

Colon adenocarcinoma (COAD) is the most common malignancy of the digestive tract, which is characterized by a dismal prognosis. No effective treatment has been established presently, thus there is an urgent need to understand the mechanisms driving COAD progression in order to develop effective therapeutic approaches and enhance clinical outcomes. In this study, we found that KLF7 is overexpressed in COAD tissues and correlated with clinicopathological features of COAD. Both gain-of-function and loss-of-function experiments have unequivocally demonstrated that overexpression of KLF7 promotes the growth and metastasis of COAD in vitro and in vivo, while KLF7 knockdown attenuated these effects. Mechanistically, our findings reveal that KLF7 can specifically bind to the promoter region of PDGFB (TGGGTGGAG), thus promoting the transcription of PDGFB and increasing its secretion. Subsequently, secreted PDGFB facilitates the progression of COAD by activating MAPK/ERK, PI3K/AKT, and JAK/STAT3 signaling pathways through PDGFRß. Additionally, we found that sunitinib can block PDGFB signaling and inhibit COAD progression, offering a promising therapeutic strategy for COAD treatment.

Cross-talk between gastric cancer and hepatic stellate cells promotes invadopodia formation during liver metastasis.

In gastric cancer (GC), the liver is a common organ for distant metastasis, and patients with gastric cancer with liver metastasis (GCLM) generally have poor prognosis. The mechanism of GCLM is unclear. Invadopodia are special membrane protrusions formed by tumor cells that can degrade the basement membrane and ECM. Herein, we investigated the role of invadopodia in GCLM. We found that the levels of invadopodia-associated proteins were significantly higher in liver metastasis than in the primary tumors of patients with GCLM. Furthermore, GC cells could activate hepatic stellate cells (HSCs) within the tumor microenvironment of liver metastases through the secretion of platelet-derived growth factor subunit B (PDGFB). Activated HSCs secreted hepatocyte growth factor (HGF), which activated the MET proto-oncogene, MET receptor of GC cells, thereby promoting invadopodia formation through the PI3K/AKT pathway and subsequently enhancing the invasion and metastasis of GC cells. Therefore, cross-talk between GC cells and HSCs by PDGFB/platelet derived growth factor receptor beta (PDGFRß) and the HGF/MET axis might represent potential therapeutic targets to treat GCLM.

Small vessel disease in primary familial brain calcification with novel truncating PDGFB variants.

INTRODUCTION: Primary familial brain calcification (PFBC) is a neurodegenerative disease characterised by bilateral calcification in the brain, especially in the basal ganglia, leading to neurological and neuropsychiatric manifestations. White matter hyperintensities (WMH) have been described in patients with PFBC and pathogenic variants in the gene for platelet-derived growth factor beta polypeptide (PDGFB), suggesting a manifest cerebrovascular process. We present below the cases of two PFBC families with PDGFB variants and stroke or transient ischaemic attack (TIA) episodes. We examine the possible correlation between PFBC and vascular events as stroke/TIA, and evaluate whether signs for vascular disease in this condition are systemic or limited to the cerebral vessels. MATERIAL AND METHODS: Two Swedish families with novel truncating PDGFB variants, p.Gln140* and p.Arg191*, are described clinically and radiologically. Subcutaneous capillary vessels in affected and unaffected family members were examined by light and electron microscopy. RESULTS: All mutation carriers showed WMH and bilateral brain calcifications. The clinical presentations differed, with movement disorder symptoms dominating in family A, and psychiatric symptoms in family B. However, affected members of both families had stroke, TIA, and/or asymptomatic intracerebral ischaemic lesions. Only one of the patients had classical vascular risk factors. Skin microvasculature was normal. CONCLUSIONS: Patients with these PDGFB variants develop microvascular changes in the brain, but not the skin. PDGFB-related small vessel disease can manifest radiologically as cerebral haemorrhage or ischaemia, and may explain TIA or stroke in patients without other vascular risk factors.

An integral blood-brain barrier in adulthood relies on microglia-derived PDGFB.

Pericyte is an indispensable cellular constituent of blood-brain barrier (BBB) and its homeostasis heavily rely on PDGFB-PDGFRß signaling. However, the primary cellular sources of PDGFB in the central nervous system (CNS) are unclear. Microglia is not considered a component of BBB and its role in maintaining BBB integrity in steady state is controversial. In this study, by analyzing transcriptomic data and performing in situ hybridization, we revealed a transition of the primary central PDGFB producers from endothelial cells in newborns to microglia in adults. Acute loss of microglial PDGFB profoundly impaired BBB integrity in adult but not newborn mice, and thus, adult mice deficient of microglial PDGFB could not survive from a sublethal endotoxin challenge due to rampant microhemorrhages in the CNS. In contrast, acute abrogation of endothelial PDGFB had minimal effects on the BBB of adult mice but led to a severe impairment of CNS vasculature in the neonates. Moreover, we found that microglia would respond to a variety of BBB insults by upregulating PDGFB expression. These findings underscore the physiological importance of the microglia-derived PDGFB to the BBB integrity of adult mice both in steady state and under injury.

Microvascular smooth muscle cells exhibit divergent phenotypic switching responses to platelet-derived growth factor and insulin-like growth factor 1.

OBJECTIVE: Vascular smooth muscle cell (VSMC) phenotypic switching is critical for normal vessel formation, vascular stability, and healthy brain aging. Phenotypic switching is regulated by mediators including platelet derived growth factor (PDGF)-BB, insulin-like growth factor (IGF-1), as well as transforming growth factor-ß (TGF-ß) and endothelin-1 (ET-1), but much about the role of these factors in microvascular VSMCs remains unclear. METHODS: We used primary rat microvascular VSMCs to explore PDGF-BB- and IGF-1-induced phenotypic switching. RESULTS: PDGF-BB induced an early proliferative response, followed by formation of polarized leader cells and rapid, directionally coordinated migration. In contrast, IGF-1 induced cell hypertrophy, and only a small degree of migration by unpolarized cells. TGF-ß and ET-1 selectively inhibit PDGF-BB-induced VSMC migration primarily by repressing migratory polarization and formation of leader cells. Contractile genes were downregulated by both growth factors, while other genes were differentially regulated by PDGF-BB and IGF-1. CONCLUSIONS: These studies indicate that PDGF-BB and IGF-1 stimulate different types of microvascular VSMC phenotypic switching characterized by different modes of cell migration. Our studies are consistent with a chronic vasoprotective role for IGF-1 in VSMCs in the microvasculature while PDGF is more involved in VSMC proliferation and migration in response to acute activities such as neovascularization. Better understanding of the nuances of the phenotypic switching induced by these growth factors is important for our understanding of a variety of microvascular diseases.

Wnt/ß-Catenin-Signaling Modulates Megakaryopoiesis at the Megakaryocyte-Erythrocyte Progenitor Stage in the Hematopoietic System.

The bone marrow (BM) hematopoietic system (HS) gives rise to blood cells originating from hematopoietic stem cells (HSCs), including megakaryocytes (MKs) and red blood cells (erythrocytes; RBCs). Many steps of the cell-fate decision remain to be elucidated, being important for cancer treatment. To explore the role of Wnt/ß-catenin for MK and RBC differentiation, we activated ß-catenin signaling in platelet-derived growth factor b (Pdgfb)-expressing cells of the HS using a Cre-lox approach (Ctnnb1BM-GOF). FACS analysis revealed that Pdgfb is mainly expressed by megakaryocytic progenitors (MKPs), MKs and platelets. Recombination resulted in a lethal phenotype in mutants (Ctnnb1BM-GOFwt/fl, Ctnnb1BM-GOFfl/fl) 3 weeks after tamoxifen injection, showing an increase in MKs in the BM and spleen, but no pronounced anemia despite reduced erythrocyte counts. BM transplantation (BMT) of Ctnnb1BM-GOF BM into lethally irradiated wildtype recipients (BMT-Ctnnb1BM-GOF) confirmed the megakaryocytic, but not the lethal phenotype. CFU-MK assays in vitro with BM cells of Ctnnb1BM-GOF mice supported MK skewing at the expense of erythroid colonies. Molecularly, the runt-related transcription factor 1 (RUNX1) mRNA, known to suppress erythropoiesis, was upregulated in Ctnnb1BM-GOF BM cells. In conclusion, ß-catenin activation plays a key role in cell-fate decision favoring MK development at the expense of erythroid production.

Breaking the feed forward inflammatory cytokine loop in the tumor microenvironment of PDGFB-driven glioblastomas.

Glioblastoma (GBM) tumor-associated macrophages (TAMs) provide a major immune cell population contributing to growth and immunosuppression via the production of proinflammatory factors, including IL-1. In this issue of the JCI, Chen, Giotti, and colleagues investigated loss of ll1b in the immune tumor microenvironment (TME) in GBM models driven by PDGFB expression and Nf1 knockdown. Survival was only improved in PDGFB-driven GBM models, suggesting that tumor cell genotype influenced the immune TME. IL-1ß in the TME increased PDGFB-driven GBM growth by increasing tumor-derived NF-κB, expression of monocyte chemoattractants, and increased infiltration of bone marrow-derived myeloid cells (BMDMs). In contrast, no requirement for IL-1ß was evident in Nf1-silenced tumors due to high basal levels of NF-κB and monocyte chemoattractants and increased infiltration of BMDM and TAMs. Notably, treatment of mice bearing PDGFB-driven GBM with anti-IL-1ß or an IL1R1 antagonist extended survival. These findings suggest that effective clinical immunotherapy may require differential targeting strategies.

Preosteoclast plays a pathogenic role in syndesmophyte formation of ankylosing spondylitis through the secreted PDGFB - GRB2/ERK/RUNX2 pathway.

OBJECTIVES: Ankylosing spondylitis (AS) is a chronic inflammatory disease that mainly affects the sacroiliac joint and spine. However, the real mechanisms of immune cells acting on syndesmophyte formation in AS are not well identified. We aimed to find the key AS-associated cytokine and assess its pathogenic role in AS. METHODS: A protein array with 1000 cytokines was performed in five AS patients with the first diagnosis and five age- and gender-matched healthy controls to discover the differentially expressed cytokines. The candidate differentially expressed cytokines were further quantified by multiplex protein quantitation (3 AS-associated cytokines and 3 PDGF-pathway cytokines) and ELISA (PDGFB) in independent samples (a total of 140 AS patients vs 140 healthy controls). The effects of PDGFB, the candidate cytokine, were examined by using adipose-derived stem cells (ADSCs) and human fetal osteoblast cell line (hFOB1.19) as in vitro mesenchymal cell and preosteoblast models, respectively. Furthermore, whole-transcriptome sequencing and enrichment of phosphorylated peptides were performed by using cell models to explore the underlying mechanisms of PDGFB. The xCELLigence system was applied to examine the proliferation, chemotaxis, and migration abilities of PDGFB-stimulated or PDGFB-unstimulated cells. RESULTS: The PDGF pathway was observed to have abnormal expression in the protein array, and PDGFB expression was further found to be up-regulated in 140 Chinese AS patients. Importantly, PDGFB expression was significantly correlated with BASFI (Pearson coefficient/p value = 0.62/6.70E - 8) and with the variance of the mSASSS score (mSASSS 2 years - baseline, Pearson coefficient/p value = 0.76/8.75E - 10). In AS patients, preosteoclasts secreted more PDGFB than the healthy controls (p value = 1.16E - 2), which could promote ADSCs osteogenesis and enhance collagen synthesis (COLI and COLIII) of osteoblasts (hFOB 1.19). In addition, PDGFB promoted the proliferation, chemotaxis, and migration of ADSCs. Mechanismly, in ADSCs, PDGFB stimulated ERK phosphorylation by upregulating GRB2 expression and then increased the expression of RUNX2 to promote osteoblastogenesis of ADSCs. CONCLUSION: PDGFB stimulates the GRB2/ERK/RUNX2 pathway in ADSCs, promotes osteoblastogenesis of ADSCs, and enhances the extracellular matrix of osteoblasts, which may contribute to pathological bone formation in AS.

Bone-derived PDGF-BB drives brain vascular calcification in male mice.

Brain vascular calcification is a prevalent age-related condition often accompanying neurodegenerative and neuroinflammatory diseases. The pathogenesis of large-vessel calcifications in peripheral tissue is well studied, but microvascular calcification in the brain remains poorly understood. Here, we report that elevated platelet-derived growth factor BB (PDGF-BB) from bone preosteoclasts contributed to cerebrovascular calcification in male mice. Aged male mice had higher serum PDGF-BB levels and a higher incidence of brain calcification compared with young mice, mainly in the thalamus. Transgenic mice with preosteoclast-specific Pdgfb overexpression exhibited elevated serum PDGF-BB levels and recapitulated age-associated thalamic calcification. Conversely, mice with preosteoclast-specific Pdgfb deletion displayed diminished age-associated thalamic calcification. In an ex vivo cerebral microvascular culture system, PDGF-BB dose-dependently promoted vascular calcification. Analysis of osteogenic gene array and single-cell RNA-Seq (scRNA-Seq) revealed that PDGF-BB upregulated multiple osteogenic differentiation genes and the phosphate transporter Slc20a1 in cerebral microvessels. Mechanistically, PDGF-BB stimulated the phosphorylation of its receptor PDGFRß (p-PDGFRß) and ERK (p-ERK), leading to the activation of RUNX2. This activation, in turn, induced the transcription of osteoblast differentiation genes in PCs and upregulated Slc20a1 in astrocytes. Thus, bone-derived PDGF-BB induced brain vascular calcification by activating the p-PDGFRß/p-ERK/RUNX2 signaling cascade in cerebrovascular cells.

A paracrine circuit of IL-1ß/IL-1R1 between myeloid and tumor cells drives genotype-dependent glioblastoma progression.

Monocytes and monocyte-derived macrophages (MDMs) from blood circulation infiltrate glioblastoma (GBM) and promote growth. Here, we show that PDGFB-driven GBM cells induce the expression of the potent proinflammatory cytokine IL-1ß in MDM, which engages IL-1R1 in tumor cells, activates the NF-κB pathway, and subsequently leads to induction of monocyte chemoattractant proteins (MCPs). Thus, a feedforward paracrine circuit of IL-1ß/IL-1R1 between tumors and MDM creates an interdependence driving PDGFB-driven GBM progression. Genetic loss or locally antagonizing IL-1ß/IL-1R1 leads to reduced MDM infiltration, diminished tumor growth, and reduced exhausted CD8+ T cells and thereby extends the survival of tumor-bearing mice. In contrast to IL-1ß, IL-1α exhibits antitumor effects. Genetic deletion of Il1a/b is associated with decreased recruitment of lymphoid cells and loss-of-interferon signaling in various immune populations and subsets of malignant cells and is associated with decreased survival time of PDGFB-driven tumor-bearing mice. In contrast to PDGFB-driven GBM, Nf1-silenced tumors have a constitutively active NF-κB pathway, which drives the expression of MCPs to recruit monocytes into tumors. These results indicate local antagonism of IL-1ß could be considered as an effective therapy specifically for proneural GBM.

PROX1 Inhibits PDGF-B Expression to Prevent Myxomatous Degeneration of Heart Valves.

BACKGROUND: Cardiac valve disease is observed in 2.5% of the general population and 10% of the elderly people. Effective pharmacological treatments are currently not available, and patients with severe cardiac valve disease require surgery. PROX1 (prospero-related homeobox transcription factor 1) and FOXC2 (Forkhead box C2 transcription factor) are transcription factors that are required for the development of lymphatic and venous valves. We found that PROX1 and FOXC2 are expressed in a subset of valvular endothelial cells (VECs) that are located on the downstream (fibrosa) side of cardiac valves. Whether PROX1 and FOXC2 regulate cardiac valve development and disease is not known. METHODS: We used histology, electron microscopy, and echocardiography to investigate the structure and functioning of heart valves from Prox1ΔVEC mice in which Prox1 was conditionally deleted from VECs. Isolated valve endothelial cells and valve interstitial cells were used to identify the molecular mechanisms in vitro, which were tested in vivo by RNAScope, additional mouse models, and pharmacological approaches. The significance of our findings was tested by evaluation of human samples of mitral valve prolapse and aortic valve insufficiency. RESULTS: Histological analysis revealed that the aortic and mitral valves of Prox1ΔVEC mice become progressively thick and myxomatous. Echocardiography revealed that the aortic valves of Prox1ΔVEC mice are stenotic. FOXC2 was downregulated and PDGF-B (platelet-derived growth factor-B) was upregulated in the VECs of Prox1ΔVEC mice. Conditional knockdown of FOXC2 and conditional overexpression of PDGF-B in VECs recapitulated the phenotype of Prox1ΔVEC mice. PDGF-B was also increased in mice lacking FOXC2 and in human mitral valve prolapse and insufficient aortic valve samples. Pharmacological inhibition of PDGF-B signaling with imatinib partially ameliorated the valve defects of Prox1ΔVEC mice. CONCLUSIONS: PROX1 antagonizes PDGF-B signaling partially via FOXC2 to maintain the extracellular matrix composition and prevent myxomatous degeneration of cardiac valves.

Isolation and Cultivation of Vascular Smooth Muscle Cells from the Mouse Circle of Willis.

INTRODUCTION: Culturing cerebrovascular smooth muscle cells (CVSMCs) in vitro can provide a model for studying many cerebrovascular diseases. This study describes a convenient and efficient method to obtain mouse CVSMCs by enzyme digestion. METHODS: Mouse circle of Willis was isolated, digested, and cultured with platelet-derived growth factor-BB (PDGF-BB) to promote CVSMC growth, and CVSMCs were identified by morphology, immunofluorescence analysis, and flow cytometry. The effect of PDGF-BB on vascular smooth muscle cell (VSMC) proliferation was evaluated by cell counting kit (CCK)-8 assay, morphological observations, Western blotting, and flow cytometry. RESULTS: CVSMCs cultured in a PDGF-BB-free culture medium had a typical peak-to-valley growth pattern after approximately 14 days. Immunofluorescence staining and flow cytometry detected strong positive expression of the cell type-specific markers alpha-smooth muscle actin (α-SMA), smooth muscle myosin heavy chain 11 (SMMHC), smooth muscle protein 22 (SM22), calponin, and desmin. In the CCK-8 assay and Western blotting, cells incubated with PDGF-BB had significantly enhanced proliferation compared to those without PDGF-BB. CONCLUSION: We obtained highly purified VSMCs from the mouse circle of Willis using simple methods, providing experimental materials for studying the pathogenesis and treatment of neurovascular diseases in vitro. Moreover, the experimental efficiency improved with PDGF-BB, shortening the cell cultivation period.

Hyaluronic acid and proteoglycan link protein 1 suppresses platelet­derived growth factor-BB-induced proliferation, migration, and phenotypic switching of vascular smooth muscle cells.

The development of atherosclerotic cardiovascular disease is associated with the phenotypic switching of vascular smooth muscle cells (SMCs) from a contractile to a synthetic state, leading to cell migration and proliferation. Platelet­derived growth factor­BB (PDGF­BB) modulates this de-differentiation by initiating a number of biological processes. In this study, we show that gene expression of hyaluronic acid (HA) and proteoglycan link protein 1 (HAPLN1) was upregulated during differentiation of human aortic SMCs (HASMCs) into a contractile state, but downregulated upon during PDGF-BB-induced dedifferentiation. This is the first study showing that the treatment of HASMCs with full-length recombinant human HAPLN1 (rhHAPLN1) significantly reversed PDGF-BB-induced decrease in the protein levels of contractile markers (SM22α, α-SMA, calponin, and SM-MHC), and inhibited the proliferation and migration of HASMCs induced by PDGF-BB. Furthermore, our results show that rhHAPLN1 significantly inhibited the phosphorylation of FAK, AKT, STAT3, p38 MAPK and Raf mediated by the binding of PDGF-BB to PDGFRß. Together, these results indicated that rhHAPLN1 can suppress the PDGF-BB-stimulated phenotypic switching and subsequent de-differentiation of HASMCs, highlighting its potential as a novel therapeutic target for atherosclerosis and other vascular diseases. [BMB Reports 2023; 56(8): 445-450].

Inhibition of p90RSK Ameliorates PDGF-BB-Mediated Phenotypic Change of Vascular Smooth Muscle Cell and Subsequent Hyperplasia of Neointima.

Platelet-derived growth factor type BB (PDGF-BB) regulates vascular smooth muscle cell (VSMC) migration and proliferation, which play critical roles in the development of vascular conditions. p90 ribosomal S6 kinase (p90RSK) can regulate various cellular processes through many different target substrates in several cell types, but the regulatory function of p90RSK on PDGF-BB-mediated cell migration and proliferation and subsequent vascular neointima formation has not yet been extensively examined. In this study, we investigated whether p90RSK inhibition protects VSMCs against PDGF-BB-induced cellular phenotypic changes and the molecular mechanisms underlying the effect of p90RSK inhibition on neointimal hyperplasia in vivo. Pretreatment of cultured primary rat VSMCs with FMK or BI-D1870, which are specific inhibitors of p90RSK, suppressed PDGF-BB-induced phenotypic changes, including migration, proliferation, and extracellular matrix accumulation, in VSMCs. Additionally, FMK and BI-D1870 repressed the PDGF-BB-induced upregulation of cyclin D1 and cyclin-dependent kinase-4 expression. Furthermore, p90RSK inhibition hindered the inhibitory effect of PDGF-BB on Cdk inhibitor p27 expression, indicating that p90RSK may induce VSMC proliferation by regulating the G0/G1 phase. Notably, treatment with FMK resulted in attenuation of neointima development in ligated carotid arteries in mice. The findings imply that p90RSK inhibition mitigates the phenotypic switch and neointimal hyperplasia induced by PDGF-BB.

Monocyte depletion enhances neutrophil influx and proneural to mesenchymal transition in glioblastoma.

Myeloid cells comprise the majority of immune cells in tumors, contributing to tumor growth and therapeutic resistance. Incomplete understanding of myeloid cells response to tumor driver mutation and therapeutic intervention impedes effective therapeutic design. Here, by leveraging CRISPR/Cas9-based genome editing, we generate a mouse model that is deficient of all monocyte chemoattractant proteins. Using this strain, we effectively abolish monocyte infiltration in genetically engineered murine models of de novo glioblastoma (GBM) and hepatocellular carcinoma (HCC), which show differential enrichment patterns for monocytes and neutrophils. Eliminating monocyte chemoattraction in monocyte enriched PDGFB-driven GBM invokes a compensatory neutrophil influx, while having no effect on Nf1-silenced GBM model. Single-cell RNA sequencing reveals that intratumoral neutrophils promote proneural-to-mesenchymal transition and increase hypoxia in PDGFB-driven GBM. We further demonstrate neutrophil-derived TNF-a directly drives mesenchymal transition in PDGFB-driven primary GBM cells. Genetic or pharmacological inhibiting neutrophils in HCC or monocyte-deficient PDGFB-driven and Nf1-silenced GBM models extend the survival of tumor-bearing mice. Our findings demonstrate tumor-type and genotype dependent infiltration and function of monocytes and neutrophils and highlight the importance of targeting them simultaneously for cancer treatments.

COL1A1-PDGFB Fusion Gene Detection Through Bulk RNA-Seq and Transcriptomic Features of Dermatofibrosarcoma Protuberans.

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a cutaneous sarcoma with obscure origin and multidirectional differentiation. Application of RNA-Seq in the detection of COL1A1-PDGFB is still at early stages. OBJECTIVE: We aim to test the efficacy of fusion gene detection using bulk RNA-Seq in DFSPs, explore altered molecular pathways and biological processes for evidences of tumor origin and cell identity shift. MATERIALS AND METHODS: Dermatofibrosarcoma protuberans and normal dermis samples were acquired for RNA-Seq. Fusion gene detection was performed using STAR-Fusion. RNA-Seq 2G yielded differentially expressed genes. Altered pathways, key gene ontology terms, and similar cell/tissue types were identified with gene set enrichment analysis. xCell was used for cell types enrichment analysis. RESULTS: 28/30 CD34(+) cases were positive for COL1A1-PDGFB. 406 upregulated and 543 downregulated genes were determined. Among the top 10 upregulated genes, 6 had neural distribution, function, or disease correlation. The upregulated genes were related to synapse, trans-synaptic signaling, neural development, and extracellular matrix. Similarities between DFSP and nervous system components were highlighted, with fibroblast cellular abundancy increased during xCell analysis. CONCLUSION: Bulk RNA-Seq provided with high detection rate of COL1A1-PDGFB. Dermatofibrosarcoma protuberans showed fibroblastic activity and neural features, which validated DFSP's fibroblast origin and tendency of neural differentiation.

[Kiwi fruit essence reduces radiation-induced lung injury by down-regulating TNF-α and PDGF-B in rats].

Objective To observe the role of tumor necrosis factor-α (TNF-α) and platelet-derived growth factor-B (PDGF-B) in kiwi fruit essence-mediated protection of radiation-induced lung injury (RILI) in rats. Methods 96 male healthy Sprague-Dawley rats were divided into normal control group, model group, and kiwi fruit essence treatment group(60 and 240 mg/kg) by the random number table method, with 24 animals in each group. The whole lungs underwent 6 MV X-ray irradiation (18 Gy) to induce RILI animal models in rats of the latter three groups. On the next day after irradiation, rats in the latter two groups were intragastrically administrated with 60 or 240 mg/kg kiwi fruit essence, once a day. The rats in the normal control and model groups were treated with 9 g/L sodium chloride solution. Eight rats in the latter three groups were randomly sacrificed on days 14, 28, and 56, while normal control rats were sacrificed on day 56 as the overall control. Blood samples were collected and separated. Serum concentrations of TNF-α and PDGF-B were detected using ELISA. The lung tissues were isolated for HE and Masson staining to evaluate alveolitis and pulmonary fibrosis (PF). The hydroxyproline (HYP) content in lung tissues was detected. The mRNA and protein expression of pulmonary TNF-α and PDGF-B were determined by quantitative real-time PCR and immunohistochemistry. Results Compared with the model group, treatment with 60 and 240 mg/kg kiwi fruit essence group significantly reduced alveolitis on days 14 and 28 as well as PF lesions on days 28 and 56. Compared with the normal control group, HYP content in the lung tissue of the model group increased on day 28 and day 56, while TNF-α and PDGF-B levels in the serum and lung tissues increased at each time point. Compared with the model group during the same period, 60 and 240 mg/kg kiwi fruit essence element treatment group reported the diminished levels of serum and pulmonary TNF-α on day 14 and day 28. Consistently, the lung tissue HYP content and serum and pulmonary PDGF-B levels on day 28 and day 56 were reduced. In addition, the above indicators in the 240 mg/kg kiwi fruit essence treatment group were lower than those for the 60 mg/kg kiwi fruit essence treatment group. Conclusion Kiwi fruit essence can alleviate RILI in rats, which is related to the down-regulation of TNF-α expression at the early stage and decreased PDGF-B level at the middle and late stages.

Cancer Cell-Derived PDGFB Stimulates mTORC1 Activation in Renal Carcinoma.

Clear cell renal cell carcinoma (ccRCC) is a hypervascular tumor that is characterized by bi-allelic inactivation of the VHL tumor suppressor gene and mTOR signalling pathway hyperactivation. The pro-angiogenic factor PDGFB, a transcriptional target of super enhancer-driven KLF6, can activate the mTORC1 signalling pathway in ccRCC. However, the detailed mechanisms of PDGFB-mediated mTORC1 activation in ccRCC have remained elusive. Here, we investigated whether ccRCC cells are able to secrete PDGFB into the extracellular milieu and stimulate mTORC1 signalling activity. We found that ccRCC cells secreted PDGFB extracellularly, and by utilizing KLF6- and PDGFB-engineered ccRCC cells, we showed that the level of PDGFB secretion was positively correlated with the expression of intracellular KLF6 and PDGFB. Moreover, the reintroduction of either KLF6 or PDGFB was able to sustain mTORC1 signalling activity in KLF6-targeted ccRCC cells. We further demonstrated that conditioned media of PDGFB-overexpressing ccRCC cells was able to re-activate mTORC1 activity in KLF6-targeted cells. In conclusion, cancer cell-derived PDGFB can mediate mTORC1 signalling pathway activation in ccRCC, further consolidating the link between the KLF6-PDGFB axis and the mTORC1 signalling pathway activity in ccRCC.

Chronic Morphine Modulates PDGFR-ß and PDGF-B Expression and Distribution in Dorsal Root Ganglia and Spinal Cord in Male Rats.

The analgesic effect of opioids decreases over time due to the development of analgesic tolerance. We have shown that inhibition of the platelet-derived growth factor beta (PDGFR-ß) signaling eliminates morphine analgesic tolerance in rats. Although the PDGFR-ß and its ligand, the platelet-derived growth factor type B (PDGF-B), are expressed in the substantia gelatinosa of the spinal cord (SG) and in the dorsal root ganglia (DRG), their precise distribution within different cell types of these structures is unknown. Additionally, the impact of a tolerance-mediating chronic morphine treatment, on the expression and distribution of PDGF-B and PDGFR-ß has not yet been studied. Using immunohistochemistry (IHC), we found that in the spinal cord, PDGFR-ß and PDGF-B were expressed in neurons and oligodendrocytes and co-localized with the mu-opioid receptor (MOPr) in opioid naïve rats. PDGF-B was also found in microglia and astrocytes. Both PDGFR-ß and PDGF-B were detected in DRG neurons but not in spinal primary afferent terminals. Chronic morphine exposure did not change the cellular distribution of PDGFR-ß or PDGF-B. However, PDGFR-ß expression was downregulated in the SG and upregulated in the DRG. Consistent with our previous finding that morphine caused tolerance by inducing PDGF-B release, PDGF-B was upregulated in the spinal cord. We also found that chronic morphine exposure caused a spinal proliferation of oligodendrocytes. The changes in PDGFR-ß and PDGF-B expression induced by chronic morphine treatment suggest potential mechanistic substrates underlying opioid tolerance.