Impact of glioma peritumoral edema, tumor size, and tumor location on alternating electric fields (AEF) therapy in realistic 3D rat glioma models: a computational study.

Objective.Alternating electric fields (AEF) therapy is a treatment modality for patients with glioblastoma. Tumor characteristics such as size, location, and extent of peritumoral edema may affect the AEF strength and distribution. We evaluated the sensitivity of the AEFs in a realistic 3D rat glioma model with respect to these properties.Approach.The electric properties of the peritumoral edema were varied based on calculated and literature-reported values. Models with different tumor composition, size, and location were created. The resulting AEFs were evaluated in 3D rat glioma models.Main results.In all cases, a pair of 5 mm diameter electrodes induced an average field strength >1 V cm-1. The simulation results showed that a negative relationship between edema conductivity and field strength was found. As the tumor core size was increased, the average field strength increased while the fraction of the shell achieving >1.5 V cm-1decreased. Increasing peritumoral edema thickness decreased the shell's mean field strength. Compared to rostrally/caudally, shifting the tumor location laterally/medially and ventrally (with respect to the electrodes) caused higher deviation in field strength.Significance.This study identifies tumor properties that are key drivers influencing AEF strength and distribution. The findings might be potential preclinical implications.

Serum levels of PDGF-CC as a potential biomarker for the diagnosis of Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is an acute systemic vasculitis of unknown etiology that predominantly affects children, and no specific diagnostic biomarkers for KD are available. Platelet-derived growth factor CC (PDGF-CC) is a peptide with angiogenic properties that has been amply demonstrated to play a critical role in the cardiovascular system. This study aimed to investigate the serum expression of PDGF-CC in children with KD and to evaluate the ability of PDGF-CC to diagnose KD. METHODS: A total of 96 subjects, including 59 KD patients, 17 febrile controls (FC), and 20 healthy controls (HC), were enrolled. Serum levels of PDGF-CC were measured via enzyme-linked immunosorbent assay. The associations between PDGF-CC and clinical laboratory parameters were investigated by correlation analysis. The diagnostic performance was assessed by receiver operating characteristic (ROC) curve analysis. RESULTS: Serum PDGF-CC levels in the KD group were significantly higher than in the FC and HC groups. Serum PDGF-CC levels in the KD group were positively correlated with white blood cell counts, percentage of neutrophils, IL-2, IL-12p70, TNF-α, and IL-1ß levels, and negatively correlated with the percentage of lymphocytes. In the analysis of ROC curves, the area under the curve was 0.796 (95% confidence interval 0.688-0.880; P < 0.0001) for PDGF-CC and increased to 0.900 (95% confidence interval 0.808-0.957; P < 0.0001) in combination with white blood cell counts and C-reactive protein. CONCLUSIONS: PDGF-CC is a potential biomarker for KD diagnosis, and the combination with white blood cell counts and C-reactive protein can further improve diagnostic performance.

PDGF-C promotes cell proliferation partially via downregulating BOP1.

Platelet-derived growth factor C (PDGF-C) is a member of PDGF/VEGF family, which is well-known for important functions in the vascular system. It is widely reported that PDGF-C is able to modulate cell proliferation. However, it is still not very clear about this cell modulating mechanism at the molecular level. In a screening of factors regulated by PDGF-C protein, we fished out a factor called block of proliferation 1 (BOP1), which is a pivotal regulator of ribosome biogenesis and cell proliferation. In this study, we investigated the regulation of BOP1 by PDGF-C and its role in modulating cell proliferation. We found that BOP1 was downregulated at both mRNA and protein levels in cells treated with PDGF-C-containing conditioned medium. On the other hand, BOP1 was upregulated in PDGF-C deficient mice. Furthermore, we confirmed that overexpression of BOP1 inhibited HEK293A cell proliferation, whereas knockdown of BOP1 promoted cell proliferation. The mitogenic effect of PDGF-C could be attenuated by downregulation of BOP1. Our results demonstrate a clear PDGF-C-BOP1 signaling that modulates cell proliferation.

Reversible promoter demethylation of PDGFD confers gemcitabine resistance through STAT3 activation and RRM1 upregulation.

Drug resistance is a major problem in cancer treatment with traditional or targeted therapeutics. Gemcitabine is approved for several human cancers and the first line treatment for locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC). However, gemcitabine resistance frequently occurs and is a major problem in successful treatments of these cancers and the mechanism of gemcitabine resistance remains largely unknown. In this study, we identified 65 genes that had reversible methylation changes in their promoters in gemcitabine resistant PDAC cells using whole genome Reduced Representation Bisulfite Sequencing analyses. One of these genes, PDGFD, was further studied in detail for its reversible epigenetic regulation in expression and shown to contribute to gemcitabine resistance in vitro and in vivo via stimulating STAT3 signaling in both autocrine and paracrine manners to upregulate RRM1 expression. Analyses of TCGA datasets showed that PDGFD positively associates with poor outcome of PDAC patients. Together, we conclude that the reversible epigenetic upregulation plays an important role in gemcitabine resistance development and targeting PDGFD signaling alleviates gemcitabine resistance for PDAC treatment.

Thermodynamic Evolution of a Metamorphic Protein: A Theoretical-Computational Study of Human Lymphotactin.

Metamorphic, or fold-switching, proteins feature different folds that are physiologically relevant. The human chemokine XCL1 (or Lymphotactin) is a metamorphic protein that features two native states, an [Formula: see text] and an all[Formula: see text] fold, which have similar stability at physiological condition. Here, extended molecular dynamics (MD) simulations, principal component analysis of atomic fluctuations and thermodynamic modeling based on both the configurational volume and free energy landscape, are used to obtain a detailed characterization of the conformational thermodynamics of human Lymphotactin and of one of its ancestors (as was previously obtained by genetic reconstruction). Comparison of our computational results with the available experimental data show that the MD-based thermodynamics can explain the experimentally observed variation of the conformational equilibrium between the two proteins. In particular, our computational data provide an interpretation of the thermodynamic evolution in this protein, revealing the relevance of the configurational entropy and of the shape of the free energy landscape within the essential space (i.e., the space defined by the generalized internal coordinates providing the largest, typically non-Gaussian, structural fluctuations).

lncRNA PITPNA-AS1 promotes cell proliferation and metastasis in hepatocellular carcinoma by upregulating PDGFD.

Hepatocellular carcinoma (HCC) ranks high in morbidity and mortality among notorious malignancies because of the lack of effective biomarkers and treatments. LncRNA PITPNA antisense RNA 1 (PITPNA-AS1) plays an oncogenic role in HCC, yet the mechanistic basis remains unprobed. Here using Bioinformatics and PCR analyses, we validated that PITPNA-AS1 expression was significantly increased in HCC. The levels of PITPNA-AS1 in tumors were reversely correlated with the prognosis in HCC patients. Downregulation of PITPNA-AS1 inhibited malignant activities of HCC cells. Next, we elucidated that PITPNA-AS1 acts as a competing endogenous RNA (ceRNA) to sponge miR-363-5p, thereby regulating the expression of platelet-derived growth factor-D (PDGFD). Moreover, the suppression of HCC cell activities by PITPNA-AS1 downregulation can be removed by PDGFD overexpression or miR-363-5p inhibition. Collectively, our work reveals the involvement of the PITPNA-AS1/miR-363-5p/PDGFD regulatory axis in HCC progression.

Age-associated microenvironmental changes highlight the role of PDGF-C in ER+ breast cancer metastatic relapse.

Patients with estrogen receptor (ER)-positive breast cancer are at risk of metastatic relapse for decades after primary tumor resection and treatment, a consequence of dormant disseminated tumor cells (DTCs) reawakening at secondary sites. Here we use syngeneic ER+ mouse models in which DTCs display a dormant phenotype in young mice but accelerated metastatic outgrowth in an aged or fibrotic microenvironment. In young mice, low-level Pdgfc expression by ER+ DTCs is required for their maintenance in secondary sites but is insufficient to support development of macrometastases. By contrast, the platelet-derived growth factor (PDGF)-Chi environment of aging or fibrotic lungs promotes DTC proliferation and upregulates tumor cell Pdgfc expression stimulating further stromal activation, events that can be blocked by pharmacological inhibition of PDGFRα or with a PDGF-C-blocking antibody. These results highlight the role of the changing microenvironment in regulating DTC outgrowth and the opportunity to target PDGF-C signaling to limit metastatic relapse in ER+ breast cancer.

Leukemia inhibitory factor, a double-edged sword with therapeutic implications in human diseases.

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the interleukin-6 (IL-6) superfamily. LIF was initially discovered as a factor to induce the differentiation of myeloid leukemia cells and thus inhibit their proliferation. Subsequent studies have highlighted the multi-functions of LIF under a wide variety of physiological and pathological conditions in a highly cell-, tissue-, and context-dependent manner. Emerging evidence has demonstrated that LIF plays an essential role in the stem cell niche, where it maintains the homeostasis and regeneration of multiple somatic tissues, including intestine, neuron, and muscle. Further, LIF exerts a crucial regulatory role in immunity and functions as a protective factor against many immunopathological diseases, such as infection, inflammatory bowel disease (IBD), and graft-verse-host disease (GVHD). It is worth noting that while LIF displays a tumor-suppressive function in leukemia, recent studies have highlighted the oncogenic role of LIF in many types of solid tumors, further demonstrating the complexities and context-dependent effects of LIF. In this review, we summarize the recent insights into the roles and mechanisms of LIF in stem cell homeostasis and regeneration, immunity, and cancer, and discuss the potential therapeutic options for human diseases by modulating LIF levels and functions.

Effects of salvianolic acid A and salvianolic acid B in renal interstitial fibrosis via PDGF-C/PDGFR-α signaling pathway.

BACKGROUND: Renal interstitial fibrosis (RIF) is the main pathological feature of end-stage renal disease (ESRD) caused by various chronic kidney diseases (CKD), and is closely related to renal dysfunction and patient prognosis. Salvianolic acid A (Sal A) and salvianolic acid B (Sal B), isolated from traditional Chinese medicine Salviae miltiorrhizae, have been confirmed to have anti-fibrotic effects on liver, cardiac and kidney. However, the precise molecular mechanism underlying the nephroprotective effects of Sal A and Sal B, and whether there is a difference between the two in RIF are still unclear. PURPOSE: This study investigated the pharmacological effects of Sal A and Sal B in RIF and explore the underlying mechanisms by in vivo and in vitro experiments. METHODS: The nephroprotective effects of Sal A, Sal B and Sal A+B were evaluated by assessing the parameters related to kidney function such as renal histology, renal function, urinary protein NAG, urinary ß2 microglobulin. In addition, RIF-related markers such as CTCF and Par3 were also detected. Thereafter, the related protein or gene levels of PDGF-C/PDGFR-α signaling pathways, apoptosis and endoplasmic reticulum stress (ERS) were determined by western blot, real-time PCR, flow cytometry or immunofluorescence staining. RESULTS: In vivo, the results showed that Sal A, Sal B and Sal A+B partially improved kidney dysfunction, increased the expression of Par-3 and reduced the expression of CTGF, PDGF-C and PDGFR-α. In vitro, the results also showed that Sal A, Sal B and Sal A+B reversed apoptosis and ERS in HSA-induced HK-2 cells via regulating PDGF-C/PDGFR-α signaling pathway. CONCLUSION: This article revealed a novel mechanism linking PDGF-C/PDGFR-α signaling pathway to RIF and suggested that Sal A, Sal B and Sal A+B were considered as potential therapeutic agents for the amelioration of RIF.

Severe cerebellar malformations in mutant mice demonstrate a role for PDGF-C/PDGFRα signalling in cerebellar development.

Formation of the mouse cerebellum is initiated in the embryo and continues for a few weeks after birth. Double-mutant mice lacking platelet-derived growth factor C (PDGF-C) and that are heterozygous for platelet-derived growth factor receptor alpha (Pdgfc-/-; PdgfraGFP/+) develop cerebellar hypoplasia and malformation with loss of cerebellar lobes in the posterior vermis. This phenotype is similar to those observed in Foxc1 mutant mice and in a human neuroimaging pattern called Dandy Walker malformation. Pdgfc-Pdgfra mutant mice also display ependymal denudation in the fourth ventricle and gene expression changes in cerebellar meninges, which coincide with the first visible signs of cerebellar malformation. Here, we show that PDGF-C/PDGFRα signalling is a critical component in the network of molecular and cellular interactions that take place between the developing meninges and neural tissues, and which are required to build a fully functioning cerebellum.

PDGF-D Prodomain Differentially Inhibits the Biological Activities of PDGF-D and PDGF-B.

As a member of PDGF/VEGF (Platelet-derived growth factor/ Vascular endothelial growth factor) growth factors, PDGF-D regulates blood vessel development, wound healing, innate immunity, and organogenesis. Unlike PDGF-A and PDGF-B, PDGF-D has an additional CUB (Complement C1r/C1s, Uegf, Bmp1) domain at the N-terminus of its growth factor domain, and thus it is secreted in a latent, inactive complex, which needs to be proteolytically activated for its biological activities. However, how the CUB domain contributes to the latency and activation of the growth factor remains elusive. In this study, we modeled the dimeric structure of PDGF-D pro-complex and studied the inhibitory functions of PDGF-D prodomain on PDGF-B and PDGF-D signaling. In our model, the growth factor domain of PDGF-D forms a VEGF-D-like dimer through their ß1 and ß3 interactions. The hinge and CUB domains of PDGF-D bind at the opposite sides of the growth factor domain and exclude the PDGFR-ß (PDGF Receptor ß) D2 and D3 domains from recognizing the growth factor. In addition, we verified that PDGF-D prodomain could inhibit both PDGF-B and PDGF-D mediated PDGFR-ß transphosphorylation in a dose-dependent manner. However, PDGF-D prodomain could only inhibit the proliferation of NIH 3T3 cells stimulated by PDGF-D but not by PDGF-B, indicating its differential inhibitory activities toward PDGF-B and PDGF-D signaling.

Role of platelet-derived growth factor c on endothelial dysfunction in cardiovascular diseases.

Loss of endothelial function is a common feature to all cardiovascular diseases (CVDs). One of the risk factors associated with the development of CVDs is the hyperglycaemia that occurs in patients with metabolic disorders such as Type 1 and Type 2 diabetes mellitus. Hyperglycaemia causes endothelial dysfunction through increased production of reactive oxygen species (ROS) from different cellular sources leading to oxidative stress. Vascular endothelial growth factor (VEGF) is essential in the stimulation and maintenance of endothelial functional aspects and, although it can mitigate the impact of ROS, VEGF-mediated signalling is partially inhibited in diabetes mellitus. The search for therapeutic strategies that preserve, protect and improve the functions of the endothelium is of great relevance in the investigation of CVDs associated with hyperglycaemia. Platelet-derived growth factor C (PDGF-C) is a peptide with angiogenic properties, independent of VEGF, that stimulates angiogenesis and revascularization of ischemic tissue. In a diabetic mouse model, PDGF-C stimulates mature endothelial cell migration, angiogenesis, endothelial progenitor cell mobilization, and increased neovascularization, and protects blood vessels in a retinal degeneration model activating anti-apoptosis and proliferation signalling pathways in endothelial cells. This review summarizes the information on the damage that high d-glucose causes on endothelial function and the beneficial effects that PDGF-CC could exert in this condition.

Efficient targeting of NY-ESO-1 tumor antigen to human cDC1s by lymphotactin results in cross-presentation and antigen-specific T cell expansion.

BACKGROUND: Type 1 conventional dendritic cells (cDC1s) are characterized by their ability to induce potent CD8+ T cell responses. In efforts to generate novel vaccination strategies, notably against cancer, human cDC1s emerge as an ideal target to deliver antigens. cDC1s uniquely express XCR1, a seven transmembrane G protein-coupled receptor. Due to its restricted expression and endocytic nature, XCR1 represents an attractive receptor to mediate antigen-delivery to human cDC1s. METHODS: To explore tumor antigen delivery to human cDC1s, we used an engineered version of XCR1-binding lymphotactin (XCL1), XCL1(CC3). Site-specific sortase-mediated transpeptidation was performed to conjugate XCL1(CC3) to an analog of the HLA-A*02:01 epitope of the cancer testis antigen New York Esophageal Squamous Cell Carcinoma-1 (NY-ESO-1). While poor epitope solubility prevented isolation of stable XCL1-antigen conjugates, incorporation of a single polyethylene glycol (PEG) chain upstream of the epitope-containing peptide enabled generation of soluble XCL1(CC3)-antigen fusion constructs. Binding and chemotactic characteristics of the XCL1-antigen conjugate, as well as its ability to induce antigen-specific CD8+ T cell activation by cDC1s, was assessed. RESULTS: PEGylated XCL1(CC3)-antigen conjugates retained binding to XCR1, and induced cDC1 chemoattraction in vitro. The model epitope was efficiently cross-presented by human cDC1s to activate NY-ESO-1-specific CD8+ T cells. Importantly, vaccine activity was increased by targeting XCR1 at the surface of cDC1s. CONCLUSION: Our results present a novel strategy for the generation of targeted vaccines fused to insoluble antigens. Moreover, our data emphasize the potential of targeting XCR1 at the surface of primary human cDC1s to induce potent CD8+ T cell responses.

RNA N6-methyladenosine demethylase FTO promotes pancreatic cancer progression by inducing the autocrine activity of PDGFC in an m6A-YTHDF2-dependent manner.

RNA N6-methyladenosine (m6A) is an emerging regulator of mRNA modifications and represents a novel player in tumorigenesis. Although it has functional significance in both pathological and physiological processes, the role of m6A modification in pancreatic ductal cancer (PDAC) remains elusive. Here, we showed that high fat mass and obesity-associated gene (FTO) expression was associated with a poor prognosis in PDAC patients and that suppression of FTO expression inhibited cell proliferation. Here, m6A sequencing (m6A-seq) was performed to screen genes targeted by FTO. The effects of FTO stimulation on the biological characteristics of pancreatic cancer cells, including proliferation and colony formation, were investigated in vitro and in vivo. The results indicate that FTO directly targets platelet-derived growth factor C (PDGFC) and stabilizes its mRNA expression in an m6A-YTHDF2-dependent manner. m6A-methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR), RNA immunoprecipitation (RIP), and luciferase reporter assays were employed to validate the specific binding of FTO to PDGFC. PDGFC upregulation led to reactivation of the Akt signaling pathway, promoting cell growth. Overall, our study reveals that FTO downregulation leads to increased m6A modifications in the 3' UTR of PDGFC and then modulates the degradation of its transcriptional level in an m6A-YTHDF2-dependent manner, highlighting a potential therapeutic target for PDAC treatment and prognostic prediction.

E3 ligase HUWE1 promotes PDGF D-mediated osteoblastic differentiation of mesenchymal stem cells by effecting polyubiquitination of ß-PDGFR.

Mesenchymal stem cells (MSCs) are adult stem cell populations and exhibit great potential in regenerative medicine and oncology. Platelet-derived growth factors (PDGFs) are well known to regulate MSC biology through their chemotactic and mitogenic properties. However, their direct roles in the regulation of MSC lineage commitment are unclear. Here, we show that PDGF D promotes the differentiation of human bone marrow mesenchymal stem cells (hBMSCs) into osteoblasts and inhibits hBMSC differentiation into adipocytes. We demonstrate that PDGF D-induced ß-actin expression and polymerization are essential for mediating this differential regulation of osteoblastogenesis and adipogenesis. Interestingly, we found that PDGF D induces massive upward molecular weight shifts of its cognate receptor, PDGF receptor beta (ß-PDGFR) in hBMSCs, which was not observed in fibroblasts. Proteomic analysis indicated that the E3 ubiquitin ligase HECT, UBA, and WWE domain-containing protein 1 (HUWE1) associates with the PDGF D-activated ß-PDGFR signaling complex in hBMSCs, resulting in ß-PDGFR polyubiquitination. In contrast to the well-known role of ubiquitin in protein degradation, we provide evidence that HUWE1-mediated ß-PDGFR polyubiquitination delays ß-PDGFR internalization and degradation, thereby prolonging AKT signaling. Finally, we demonstrate that HUWE1-regulated ß-PDGFR signaling is essential for osteoblastic differentiation of hBMSCs, while being dispensable for PDGF D-induced hBMSC migration and proliferation as well as PDGF D-mediated inhibition of hBMSC differentiation into adipocytes. Taken together, our findings provide novel insights into the molecular mechanism by which PDGF D regulates the commitment of hBMSCs into the osteoblastic lineage.

PDGF-D-PDGFRß signaling enhances IL-15-mediated human natural killer cell survival.

The axis of platelet-derived growth factor (PDGF) and PDGF receptor-beta (PDGFRß) plays prominent roles in cell growth and motility. In addition, PDGF-D enhances human natural killer (NK) cell effector functions when binding to the NKp44 receptor. Here, we report an additional but previously unknown role of PDGF-D, whereby it mediates interleukin-15 (IL-15)-induced human NK cell survival but not effector functions via its binding to PDGFRß but independent of its binding to NKp44. Resting NK cells express no PDGFRß and only a low level of PDGF-D, but both are significantly up-regulated by IL-15, via the nuclear factor κB signaling pathway, to promote cell survival in an autocrine manner. Both ectopic and IL-15-induced expression of PDGFRß improves NK cell survival in response to treatment with PDGF-D. Our results suggest that the PDGF-D-PDGFRß signaling pathway is a mechanism by which IL-15 selectively regulates the survival of human NK cells without modulating their effector functions.

V-CARMA: A tool for the detection and modification of antigen-specific T cells.

T cells promote our body's ability to battle cancers and infectious diseases but can act pathologically in autoimmunity. The recognition of peptides presented by major histocompatibility complex (pMHC) molecules by T cell receptors (TCRs) enables T cell-mediated responses. To modify disease-relevant T cells, new tools to genetically modify T cells and decode their antigen recognition are needed. Here, we present an approach using viruses pseudotyped with peptides loaded on MHC called V-CARMA (Viral ChimAeric Receptor MHC-Antigen) to specifically target T cells expressing cognate TCRs for antigen discovery and T cell engineering. We show that lentiviruses displaying antigens on human leukocyte antigen (HLA) class I and class II molecules can robustly infect CD8+ and CD4+ T cells expressing cognate TCRs, respectively. The infection rates of the pseudotyped lentiviruses (PLVs) are correlated with the binding affinity of the TCR to its cognate antigen. Furthermore, peptide-HLA pseudotyped lentivirus V-CARMA constructs can identify target cells from a mixed T cell population, suppress PD-1 expression on CD8+ T cells via PDCD1 shRNA delivery, and induce apoptosis in autoreactive CD4+ T cells. Thus, V-CARMA is a versatile tool for TCR ligand identification and selective T cell manipulation.