Down-regulation Of Platelet-derived Growth Factor Research Articles

Spatial Transcriptomic Analysis of Focal and Normal Areas of Myocyte Disarray in Human Hypertrophic Cardiomyopathy.

Hypertrophic Cardiomyopathy (HCM) is a common inherited disorder that can lead to heart failure and sudden cardiac death, characterized at the histological level by focal areas of myocyte disarray, hypertrophy and fibrosis, and only a few disease-targeted therapies exist. To identify the focal and spatially restricted alterations in the transcriptional pathways and reveal novel therapeutic targets, we performed a spatial transcriptomic analysis of the areas of focal myocyte disarray compared to areas of normal tissue using a commercially available platform (GeoMx, nanoString). We analyzed surgical myectomy tissue from four patients with HCM and the control interventricular septum tissue from two unused organ donor hearts that were free of cardiovascular disease. Histological sections were reviewed by an expert pathologist, and 72 focal areas with varying degrees of myocyte disarray (normal, mild, moderate, severe) were chosen for analysis. Areas of interest were interrogated with the Human Cancer Transcriptome Atlas designed to profile 1800 transcripts. Differential expression analysis revealed significant changes in gene expression between HCM and the control tissue, and functional enrichment analysis indicated that these genes were primarily involved in interferon production and mitochondrial energetics. Within the HCM tissue, differentially expressed genes between areas of normal and severe disarray were enriched for genes related to mitochondrial energetics and the extracellular matrix in severe disarray. An analysis of the gene expression of the ligand-receptor pair revealed that the HCM tissue exhibited downregulation of platelet-derived growth factor (PDGF), NOTCH, junctional adhesion molecule, and CD46 signaling while showing upregulation of fibronectin, CD99, cadherin, and amyloid precursor protein signaling. A deconvolution analysis utilizing the matched single nuclei RNA-sequencing (snRNA-seq) data to determine cell type composition in areas of interest revealed significant differences in fibroblast and vascular cell composition in areas of severe disarray when compared to normal areas in HCM samples. Cell composition in the normal areas of the control tissue was also divergent from the normal areas in HCM samples, which was consistent with the differential expression results. Overall, our data identify novel and potential disease-modifying targets for therapy in HCM.

Response of immature rats to a low dose of nanoparticulate silver: Alterations in behavior, cerebral vasculature-related transcriptome and permeability

The increasing production and use of silver nanoparticles (AgNPs) as antimicrobial agents in medicinal and commercial products creates a substantial risk of exposure, especially for infants and children. Our current knowledge concerning the impact of AgNPs on developing brain is insufficient. Therefore we investigated the temporal profile of transcriptional changes in cellular components of the neurovascular unit in immature rats exposed to a low dose of AgNPs. The behavior of animals under these conditions was also monitored. Significant deposition of AgNPs in brain of exposed rats was identified and found to persist over the post-exposure time. Substantial changes were noted in the transcriptional profile of tight junction proteins such as occludin and claudin-5, and pericyte-related molecules such as angiopoietin-1. Moreover, downregulation of platelet-derived growth factor (PDGFβ) and its receptor (PDGFβR) which constitute the main signaling pathway between endothelial cells and pericytes was observed. These were long-lasting effects, accompanied by overexpression of astroglial-specific GFAP mRNA and endothelial cell adhesion molecule, ICAM-1, involved in the pathomechanism of neuroinflammation. The profile of changes indicates that even low doses of AgNPs administered during the early stage of life induce dysregulation of neurovascular unit constituents which may lead to disintegration of the blood-brain barrier. This was confirmed by ultrastructural analysis that revealed enhanced permeability of cerebral microvessels resulting in perivascular edema. Changes in the behavior of exposed rats indicating pro-depressive and anti-anxiety impacts were also identified. The results show a high risk of using AgNPs in medical and consumer products dedicated for infants and children.

Metformin inhibits metastatic breast cancer progression and improves chemosensitivity by inducing vessel normalization via PDGF-B downregulation

BackgroundVascular maturity and functionality are closely associated with tumor progression and chemosensitivity. The antidiabetic agent metformin has shown its ability to inhibit tumor angiogenesis in metastatic breast cancer models. However, it remains unclear if or how metformin remodels the abnormal vasculature of metastatic breast cancer, while inhibiting angiogenesis.MethodsMetastatic breast cancer models were constructed to compare microvessel density (MVD), vascular maturity and function, lung metastasis and chemosensitivity in metformin-treated or untreated mice. Protein array assay and transcriptome sequencing were performed for genetic screening. Lentiviral shRNA-PDGF-B transfection was used for observing the contribution of PDGF-B knockdown to metformin’s vascular effects.ResultsMetastatic breast cancers were characterized by an excessively angiogenic, immature and morphologically abnormal vasculature. Compared to control, metformin significantly reduced MVD, leakage and hypoxia, and increased vascular mural cells coverage and perfusion, namely, “vessel normalization”. Metformin at human blood concentrations had no direct effect on the migration and proliferation of cancer cells. Based on that, reduced lung metastasis of the primary tumor and improved chemosensitization by metformin were assumed to be mediated via metformin’s vascular effects. Further results of genetic screening and in vivo experiments showed that the downregulation of platelet-derived growth factor B (PDGF-B) greatly contributed to the metformin-induced vessel normalization.ConclusionsThese findings provide pre-clinical evidences for the vascular mechanism of metformin-induced metastasis inhibition and the chemosensitization of metastatic breast cancers.

Proteomic profiling of senescent human diploid fibroblasts treated with gamma-tocotrienol

BackgroundReplicative senescence of human diploid fibroblasts (HDFs) has been used as a model to study mechanisms of cellular aging. Gamma-tocotrienol (γT3) is one of the members of vitamin E family which has been shown to increase proliferation of senescent HDFs. However, the modulation of protein expressions by γT3 in senescent HDFs remains to be elucidated. Therefore, this study aimed to determine the differentially expressed proteins (DEPs) in young and senescent HDFs; and in vehicle- and γT3-treated senescent HDFs using label-free quantitative proteomics.MethodsWhole proteins were extracted and digested in-gel with trypsin. Peptides were detected by Orbitrap liquid chromatography mass spectrometry. Mass spectra were identified and quantitated by MaxQuant software. The data were further filtered and analyzed statistically using Perseus software to identify DEPs. Functional annotations of DEPs were performed using Panther Classification System.ResultsA total of 1217 proteins were identified in young and senescent cells, while 1218 proteins in vehicle- and γT3-treated senescent cells. 11 DEPs were found in young and senescent cells which included downregulation of platelet-derived growth factor (PDGF) receptor beta and upregulation of tubulin beta-2A chain protein expressions in senescent cells. 51 DEPs were identified in vehicle- and γT3-treated senescent cells which included upregulation of 70 kDa heat shock protein, triosephosphate isomerase and malate dehydrogenase protein expressions in γT3-treated senescent cells.ConclusionsPDGF signaling and cytoskeletal structure may be dysregulated in senescent HDFs. The pro-proliferative effect of γT3 on senescent HDFs may be mediated through the stimulation of cellular response to stress and carbohydrate metabolism. The expressions and roles of these proteins in relation to cellular senescence are worth further investigations. Data are available via ProteomeXchange with identifier PXD009933.

Electro-Acupuncture Treatment Improves Neurological Function Associated with Downregulation of PDGF and Inhibition of Astrogliosis in Rats with Spinal Cord Transection

The aim of the current study was to determine the effects of electro-acupuncture (EA) on the improvement of locomotor function in injured spinal cord and underlying mechanism. Forty-five female Sprague-Dawley rats (180~200 g) were randomly divided into three groups, sham operation control group (sham), spinal cord transection group (SCT) and EA group. The Basso, Beattie, and Bresnahan (BBB) Locomotor Rating Scale was used to evaluate functional recovery of rats in hindlimbs at 1, 3, 5 weeks after injury and EA therapy. The gene and protein expression of glial fibrillary acidic protein (GFAP) and platelet derived growth factor (PDGF) were measured by reverse transcription-polymerase chain reaction and Western blot analysis, respectively, and the number of GFAP-positive cells was counted, also. Compared with SCT group, the locomotor function in hindlimbs of rats was improved after 1, 3, 5 weeks following EA therapy. EA treatment not only decreased effectively the number of GFAP immunostaining and GFAP expression, but also downregulated the PDGF expression both gene and protein, in addition decreased the number of PDGF immunostaining in injured spinal cord of rats with transection. It therefore concluded that EA therapy can significantly promote the recovery of locomotor function, and this may be linked to the inhibition of astrogliosis, together with the downregulation of PDGF.

SpontaneousIn VitroTransformation of Adult Neural Precursors into Stem-Like Cancer Cells

Recent studies have found that cellular self-renewal capacity in brain cancer is heterogeneous, with only stem-like cells having this property. A link between adult stem cells and cancer stem cells remains, however, to be shown. Here, we describe the emergence of cancer stem-like cells from in vitro cultured brain stem cells. Adult rat subventricular zone (SVZ) stem cells transformed into tumorigenic cell lines after expansion in vitro. These cell lines maintained characteristic features of stem-like cells expressing Nestin, Musashi-1 and CD133, but continued to proliferate upon differentiation induction. Karyotyping detected multiple acquired chromosomal aberrations, and syngeneic transplantation into the brain of adult rats resulted in malignant tumor formation. Tumors revealed streak necrosis and displayed a neural as well as an undifferentiated phenotype. Deficient downregulation of platelet-derived growth factor (PDGF) receptor alpha was identified as candidate mechanism for tumor cell proliferation, and its knockdown by siRNA resulted in a reduction of cell growth. Our data point to adult brain precursor cells to be transformed in malignancies. Furthermore, in vitro expansion of adult neural stem cells, which will be mandatory for therapeutic strategies in neurological disorders, also harbors the risk for amplifying precursor cells with acquired genetic abnormalities and induction of malignant tumors after transplantation.

Regulation of PDGF production and ERK activation by estrogen is associated with TSC2 gene expression.

Mechanisms that regulate the growth response to estrogen (17beta-estradiol, E2) are poorly understood. Recently, loss of function of the tuberous sclerosis complex 2 (TSC2) gene has been associated with E2-related conditions that are characterized by benign cellular proliferation. We examined the growth response to E2 in vascular smooth muscle cells (VSMCs) that possess wild-type TSC2 and compared them with ELT-3 smooth muscle cells that do not express TSC2. In TSC2-expressing VSMCs, growth inhibition in response to E2 was associated with downregulation of platelet-derived growth factor (PDGF), PDGF receptor (PDGFR), and limited activation of extracellular signal-regulated kinase (ERK). In contrast, the growth-promoting effect of E2 in TSC2-null ELT-3 cells was associated with induction of PDGF, robust phosphorylation of PDGFR, and sustained activation of ERK. Furthermore, in ELT-3 cells, cellular growth and ERK activation by E2 were inhibited by the PDGFR inhibitor tyrphostin AG 17 and by PDGF-neutralizing antibody. These results demonstrate that autocrine production of PDGF and augmentation of the ERK pathway leads to estrogen-induced cellular proliferation in TSC2-null cells, a pathway that was downregulated in cells that express TSC2. Understanding the mechanisms that regulate the diverse responses to the steroid hormone estrogen could lead to novel approaches to the treatment of estrogen-related diseases that are characterized by aberrant cell proliferation.

Sialylation and sulfation of lactosylceramide distinctly regulate anchorage-independent growth, apoptosis, and gene expression in3LL Lewis lung carcinoma cells

To investigate the significance of sialylation and sulfation of lactosylceramide in transformed cells, we established ganglioside GM3- and lactosylsulfatide (SM3)-reconstituted cells by transfecting cDNAs of GM3 synthase and cerebroside sulfotransferase into the J5 subclone of 3LL Lewis lung carcinoma cells. The J5 clone was selected for the transfection of these genes because it lacks GM3 and SM3 but accumulates lactosylceramide. The anchorage-dependent growth of both GM3- and SM3-reconstituted cells was similar. However, anchorage-independent growth (as measured by colony-forming ability in soft agar) of the SM3- reconstituted cells was almost completely lost, which supports our previous observation showing the suppression of tumorigenic potential in vivo and beta1 integrin gene expression induced by the introduction of cerebroside sulfotransferase gene (Kabayama et al. [2001] J. Biol. Chem., 276, 26777-26783). The GM3-reconstituted cells formed a significantly higher number of colonies in soft agar compared to mock-transfected cells and began to proliferate and become resistant to apoptosis when serum was depleted, indicating that endogenous GM3 is essential for maintaining these fundamental properties of malignant cells. We also found that serum-induced ERK1/2 activation was suppressed in the GM3-reconstituted cells, suggesting that anchorage-independent cell cycle initiation by endogenous GM3 is elicited through pathway(s) independent of ERK1/2 activation. The selective down-regulation of platelet-derived growth factor (PDGF)-dependent ERK1/2 activation in the GM3-reconstituted cells was due to the substantial decreases of PDGF alpha receptor mRNA and protein, but in the SM3-reconstituted cells PDGF alpha receptor expression was similar to mock cells. Thus, endogenously produced GM3 and SM3 differentially and distinctly regulate tumor-progression ability, that is, GM3 leads the transformed phenotype of J5 cells to promotion and SM3 to abrogation.

Direct effects of simvastatin on proliferation and matrix accumulation in cultured murine mesangial cells

Background. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been demonstrated to suppress glomerular injuries in various renal diseases. However, it is not fully clear whether HMG-CoA reductase inhibitors directly regulate matrix protein accumulation in mesangial cells. Methods. We investigated the effect of simvastatin (SIM), an HMG-CoA reductase inhibitor, on DNA synthesis in cultured murine mesangial cells stimulated by fetal calf serum (FCS). We then determined whether SIM affected the expression of regulatory factors of cell growth and matrix protein accumulation, using Northern analysis. Results. SIM dose-dependently inhibited FCS-induced DNA synthesis after 24 h of incubation. SIM treatment for 24 h suppressed the mRNA expression of platelet-derived growth factor (PDGF)-B chain, PDGF receptor β-subunit and c-myc, while the expression of transforming growth factor β (TGF-β) was not affected. Concerning matrix protein synthesis, the mRNA expression of type IV collagen was suppressed, whereas that of type III collagen was markedly upregulated. As for matrix turnover proteins, SIM had a markedly suppressive effect on the mRNA expression of plasminogen activator inhibitor-1 (PAI-1), with a constant expression of tissue-type plasminogen activator (tPA). Conclusions. These results indicate that SIM may sup-press mesangial cell proliferation in part through the downregulation of PDGF, PDGF-receptor, and c-myc mRNA expressions. In addition, the suppression of the synthesis of collagen IV and PAI-1 appears to be a direct inhibitory effect of SIM on glomerular matrix accumulation.

The Inactivation Mechanism of Low Molecular Weight Phosphotyrosine-protein Phosphatase by H2O2

Low molecular weight phosphotyrosine-protein phosphatase (LMW-PTP) shares no general sequence homology with other PTPs, although it has an active site sequence motif CXXXXXR and a reaction mechanism identical to those of all PTPs. The main function of this enzyme is the down-regulation of platelet-derived growth factor and insulin receptors. Both human LMW-PTP isoenzymes are inactivated by H2O2. The enzymes are protected from inactivation by Pi, a competitive inhibitor, suggesting that the H2O2 reaction is directed to active site. Analysis of free thiols performed on the inactivated enzymes demonstrates that only two out of the eight LMW-PTP cysteines are modified. Time-course high performance liquid chromatography-electrospray mass spectrometry, together with specific radiolabeling and tryptic fingerprint analyses, enables us to demonstrate that H2O2 causes the oxidation of Cys-12 and Cys-17 to form a disulfide bond. Because both residues are localized into the active site region, this modification inactivates the enzyme. Fluorescence spectroscopy experiments suggest that the fold of the enzyme is modified during oxidation by H2O2. Because a physiological concentration of H2O2 produces enzyme inactivation and considering that the activity is restored by reduction with low molecular weight thiols, we suggest that oxidative stress conditions and other processes producing hydrogen peroxide regulate the LMW-PTP in the cell.

Morphogenic effects of endothelin-1 on vascular smooth muscle cells.

Endothelin-1 (ET-1), a vasoconstrictor peptide produced by endothelial and vascular smooth muscle cells (VSMC) might play a role in vascular remodelling. To investigate the proposed 'mitogenic' potential of ET-1, we examined the effects of chronic exposure of VSMC to ET-1 on cell cycle, growth/proliferation and differentiation under essentially mitogen-free culture conditions. Bulk cultures of thoracic aortic VSMC of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats, although exhibiting genetically determined differences in growth/proliferation (due to shortened G1 and G2 phases in SHR VSMC), respond in a similar manner to ET-1 exposure: long-term exposure (12-15 days) of VSMC from both sources to ET-1 in nonmitogenic medium did not promote cycling of cells. On the contrary, ET-1 attenuated the cycling of VSMC which had already cycled beyond the S phase. For cells which had not cycled beyond the S phase, ET-1 interrupted progression through the cell cycle at the late G1/early S phase. The specific ability of SHR VSMC to grow in mitogen-free medium was abolished by ET-1, most likely via down-regulation of platelet-derived growth factor (PDGF)-alpha receptors. Subsequent to ET-1 exposure, VSMC expressed increased levels of mRNA and protein for smooth-muscle-specific alpha-actin. However, expression of smooth muscle alpha-actin did not predominate over beta-actin as observed for adult contractile VSMC in vivo. The ET-1-induced expression of smooth-muscle-specific alpha-actin mRNA was dose dependent (EC50 approx. 2 x 10(-9) M), and alpha-actin protein expressed was associated with organized actin fibers.