Platelet-derived Growth Factor Receptor-α Research Articles

Imatinib mesylate inhibits androgen-independent PC-3 cell viability, proliferation, migration, and tumor growth by targeting platelet-derived growth factor receptor-α

AimThe abnormal expression of oncogenic tyrosine kinase receptors such as platelet-derived growth factor receptors (PDGFRs) has been reported in cancer progression. However, the role of PDGFRs in the human androgen-independent prostate cancer PC-3 cell line is not well understood. Thus, this study examined the role of PDGFRs in androgen-independent PC-3 cells. Main methodsPDGFR mRNA and protein expression was determined by quantitative real-time PCR and western blotting, respectively. The effects of the tyrosine kinase inhibitor imatinib (imatinib mesylate) and small interfering RNAs (siRNAs) were determined by a Cell Counting Kit-8 assay, bromodeoxyuridine assay, and Transwell migration assay. The in vivo effect of imatinib was analyzed using a tumor formation assay in nude mice. Key findingsPDGFRα was upregulated in androgen-independent PC-3 cells compared with normal prostate epithelial cells. PDGF-BB induced the phosphorylation of PDGFRα and downstream signaling molecules, including Akt, in a dose-dependent manner. Imatinib reduced the phosphorylation of the PDGFRα/Akt axis. Imatinib also suppressed the viability, proliferation, migration, and tumor growth of PC-3 cells. PDGFRα knockdown by siRNA decreased the viability and migration of PC-3 cells. SignificanceThese results demonstrated the distinct contribution of PDGFRα signaling to the proliferation and migration of PC-3 cells and suggested the potential for PDGFRα as a therapeutic target for metastatic and androgen-independent prostate cancer.

Current update on molecular cytogenetics, diagnosis and management of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal (GI) tract and are thought to arise from precursors of the interstitial cells of Cajal. GISTs can arise anywhere in the GI tract, but most commonly originate from the stomach and small intestine. The majority of GISTs occur as a result of activating mutations in two receptor protein tyrosine kinases: KIT and/or platelet-derived growth factor receptor-α. Mutational analyses allow for predicting patient prognosis and treatment response. Clinical presentations can vary from no symptoms, typical in the case of small incidentally found tumors, to GI bleeding, abdominal discomfort, and ulcer-related symptoms when the tumor is enlarged. Imaging plays a critical role in the diagnosis and management of these tumors with multiphasic computed tomography serving as the imaging modality of choice. Magnetic resonance imaging and positron emission tomography-computed tomography can serve as imaging adjuncts in lesion characterization, especially with liver metastases, and subsequent staging and assessment for treatment response or recurrence. Surgical resection is the preferred management for small GISTs, while tyrosine kinase inhibitors − imatinib mesylate and sunitinib malate − serve as crucial molecular-targeted therapies for locally advanced and metastatic GISTs. This review article highlights the clinical presentation, pathology and molecular cytogenetics, imaging features, and current management of GISTs.

Curc-mPEG454, a PEGylated curcumin derivative, as a multi-target anti-fibrotic prodrug

Our previous studies demonstrated that Curc-mPEG454, a curcumin derivative modified with short-chain polyethylene glycol (PEG), not only increased the blood concentration of curcumin, but also retained its anti-inflammatory activity. Here, we aimed to evaluate the anti-fibrotic effect of Curc-mPEG454 on a rat liver fibrosis model induced by carbon tetrachloride (CCl4), and to explore the underlying mechanisms by integrating our total liver RNA sequencing (RNA-seq) data with recent liver single-cell sequencing (scRNA-seq) studies. 50 mg/kg and 100 mg/kg Curc-mPEG454 treatment significantly reduced the elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) induced by CCl4, and the incidence of liver cirrhosis decreased from 75% to 37% and 35%, respectively. RNA-seq analysis revealed that Curc-mPEG454 significantly upregulated aldehyde oxidase 1 (AOX1) while downregulated cytochrome p450 26A1 (CYP26A1) and cytochrome p450 26B1 (CYP26B1) resulting in restoring liver retinoic acid (RA) level, increased glutamate-cysteine ligase catalytic subunit (GCLC) and glutamate-cysteine ligase modifier subunit (GCLM) expression to synthesize hepatic glutathione (GSH), and inhibited liver inflammation via down-regulating the Prostaglandin E Synthase 2 (PTGES2)/prostacyclin E2 (PGE2) signaling. Integrating scRNA-seq data revealed that Curc-mPEG454 effectively inhibited the expansion of scar-associated macrophage subpopulation and scar-producing myofibroblasts in the damaged liver, and remodeled the fibrotic niche via regulation of ligand-receptor interactions including platelet-derived growth factor-B (PDGF-B)/platelet-derived growth factor receptor-α (PDGFR-α) signaling. As a multi-target prodrug, PEGylated curcumin deserves further attention and research.

PDGFRα Enhanced Infection of Breast Cancer Cells with Human Cytomegalovirus but Infection of Fibroblasts Increased Prometastatic Inflammation Involving Lysophosphatidate Signaling.

Human cytomegalovirus (HCMV) infects 40–70% of adults in developed countries. HCMV proteins and DNA are detected in tumors and metastases, suggesting an association with increased invasion. We investigated HCMV infection in human breast cancer cell lines compared to fibroblasts, a component of tumors, and the role of platelet-derived growth factor receptor-α (PDGFRα). HCMV productively infected HEL299 fibroblasts and, to a lesser extent, Hs578T breast cancer cells. Infection of another triple-negative cell line, MDA-MB-231, and also MCF-7 cells, was extremely low. These disparate infection rates correlated with expression of PDGFRA, which facilitates HCMV uptake. Increasing PDGFRA expression in T-47D breast cancer and BCPAP thyroid cancer cells markedly increased HCMV infection. Conversely, HCMV infection decreased PDGFRA expression, potentially attenuating signaling through this receptor. HCMV infection of fibroblasts promoted the secretion of proinflammatory factors, whereas an overall decreased secretion of inflammatory factors was observed in infected Hs578T cells. We conclude that HCMV infection in tumors will preferentially target tumor-associated fibroblasts and breast cancer cells expressing PDGFRα. HCMV infection in the tumor microenvironment, rather than cancer cells, will increase the inflammatory milieu that could enhance metastasis involving lysophosphatidate.

A Cipadesin Limonoid and a Tirucallane Triterpene from the Fruit of Sandoricum koetjape and their Inhibitory Properties against Receptor Tyrosine Kinases

A new cipadesin limonoid, i.e. 3-epi-cipadonoid C (1), and a new tirucallane triterpene, i.e. hispidol B 3-palmitate (3), have been isolated from the seeds and fruit peels extract of Sandoricum koetjape, respectively. Along with these compounds the known limonoid, cipaferen G (2), and two pentacyclic triterpenes, bryonolic (4) and bryononic (5) acids, were also isolated. The strucrures of the new compounds were elucidated by the analysis of NMR and mass spectral data. Compounds 1 - 5 were evaluated as the inhibitor of receptor tyrosine kinases (EGFR, Epidermal Growth Factor Receptor; HER2, HER4, Human Epidermal growth factor Receptor 2, -4; IGFR, Insulin-like Growth Factor Receptor; InsR, Insulin Receptor; KDR, Kinase insert Domain Receptor; PDGFRα, and PDGFRβ, Platelet-Derived Growth Factor Receptor-α and -β). The results showed only 1 and 3 that have weak activity against InsR.

Platelet-Derived Growth Factor Receptor-α Subunit Targeting Suppresses Metastasis in Advanced Thyroid Cancer In Vitro and In Vivo.

Thyroid cancer is the most common endocrine malignancy. Patients with well-differentiated thyroid cancers, such as papillary and follicular cancers, have a favorable prognosis. However, poorly differentiated thyroid cancers, such as medullary, squamous and anaplastic advanced thyroid cancers, are very aggressive and insensitive to radioiodine treatment. Thus, novel therapies that attenuate metastasis are urgently needed. We found that both PDGFC and PDGFRA are predominantly expressed in thyroid cancers and that the survival rate is significantly lower in patients with high PDGFRA expression. This finding indicates the important role of PDGF/PDGFR signaling in thyroid cancer development. Next, we established a SW579 squamous thyroid cancer cell line with 95.6% PDGFRA gene insertion and deletions (indels) through CRISPR/Cas9. Protein and invasion analysis showed a dramatic loss in EMT marker expression and metastatic ability. Furthermore, xenograft tumors derived from PDGFRA gene-edited SW579 cells exhibited a minor decrease in tumor growth. However, distant lung metastasis was completely abolished upon PDGFRA gene editing, implying that PDGFRA could be an effective target to inhibit distant metastasis in advanced thyroid cancers. To translate this finding to the clinic, we used the most relevant multikinase inhibitor, imatinib, to inhibit PDGFRA signaling. The results showed that imatinib significantly suppressed cell growth, induced cell cycle arrest and cell death in SW579 cells. Our developed noninvasive apoptosis detection sensor (NIADS) indicated that imatinib induced cell apoptosis through caspase-3 activation. In conclusion, we believe that developing a specific and selective targeted therapy for PDGFRA would effectively suppress PDGFRA-mediated cancer aggressiveness in advanced thyroid cancers.

Expression of Platelet Derived Growth Factor a, Its Receptor, and Integrin Subunit Alpha V in Feline Injection-Site Sarcomas

Abstract Injection-site sarcomas are considered an important entity in veterinary oncology, especially in cats. The current study investigated the immunohistochemical expression of platelet-derived growth factor A (PDGFA), platelet-derived growth factor receptor-α (PDGFR-α), and integrin alpha subunit v in feline injection-site sarcomas (FISS). A total of 14 paraffin-embedded tissue samples previously diagnosed as soft tissue sarcomas were selected from the departmental archive and sectioned at 5µm using a microtome. Tissue sections were stained with Hematoxylin & Eosin, Alcian blue-Periodic Acid Schiff (AB-PAS), Masson’s Trichrome, and immunohistochemically for PDGFA, PDGR-α, and integrin alpha v. The majority of the tumors were fibrosarcomas (n=13/14), except one case of myxoid liposarcoma. The tumors occurred at sites commonly used for injections or vaccine administration. Histologically, tumors were characterized by peripheral infiltration of mononuclear cells mainly lymphocytes, variable sized central necrotic areas, and many multinucleated tumor giant cells. AB-PAS staining revealed the presence of myxoid or mucinous areas in (8/14) tumors while trichrome staining demonstrated a variable amount of collagenous stroma in 12/14 tumors. Vimentin immunoreactivity was observed in all the tumors while smooth muscle actin and muscle actin staining was noticed in four and two cases, respectively. PDGFA and PDGFR-α immunoexpression was observed in all 14 cases while integrin alpha v in 13/14 cases. The results of the current study indicate that fibrosarcoma is the major morphologic phenotype of FISS. The PDGFA, its receptor, and integrin alpha v immunoexpression are increased in these tumors in cats which elucidates their role in the pathogenesis of FISS.

Characterization of the Expression of Vacuolar Protein Sorting 11 (Vps11) in Mammalian Oligodendrocytes.

A founder mutation in human VPS11 (Vacuolar Protein Sorting 11) was recently linked to a genetic leukoencephalopathy in Ashkenazi Jews that presents with the classical features of white matter disorders of the central nervous system (CNS). The neurological deficits include hypomyelination, hypotonia, gradual loss of vision, and seizures. However, the cells expressing the mutation were not identified. Here we describe, using immunocytochemistry, the strong expression of Vps11 in mouse oligodendrocytes and, specifically, its localization with Myelin Associated Glycoprotein (MAG) in the inner tongue of myelin. In longitudinal sections of myelin, it forms a bead-like structure, alternating with Myelin Basic Protein (MBP). Immunofluorescent staining with Vps11 and neurofilament proteins indicates the absence of Vps11 in axons in vivo. Finally, changes in Vps11 expression are associated with altered proteolipid protein (PLP) levels based upon mice with duplications or deletions of the Plp1 gene. To determine potential functional contributions of Vps11, we combined Vps11 with Platelet Derived Growth Factor Receptor-α (PDGFRα) in vitro and in vivo: in both conditions, co-localization of the two proteins was frequently found in round vesicles of OPCs/oligodendrocytes, suggesting retrograde transport for degradation by the endolysosomal system. Neuron-to-glial communication has been invoked to explain degenerative changes in myelin followed by degenerative changes in axons, and vice versa; but to our knowledge, no specific proteins in retrograde transport from the myelin inner tongue to oligodendrocyte perikarya have been identified. The identification of mutations in VPS11 and its localization at the axon-myelin interface should open new avenues of research.

The role of angiogenetic single-nucleotide polymorphisms in thymic malignancies and thymic benign lesions.

BackgroundWe previously showed that selected single-nucleotide-polymorphisms (SNPs) of genes involved in angiogenesis influence the aggressiveness of thymic epithelial tumors (TETs). This study analyzes their role in TETs and in thymic benign lesions, in order to investigate potential correlation with risk and outcome.MethodsGenomic DNA was extracted from paraffin-embedded tissue of 92 patients, undergoing surgery at our Institution. We investigated by Real-Time PCR the SNPs of the following genes: platelet-derived growth factor receptor-α (PDGFRα), hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGF-A), vascular endothelial growth factor receptor-2 and 3 (VEGF-2, VEGFR-3), excision repair cross-complementation group-1 (ERCC1).ResultsFifty-seven TETs and 35 thymic benign lesions were included into the study. Frequency of SNPs was as follows: rs2057482 C, rs11158358 C and rs11549465 C polymorphisms of HIF1-a: thymomas < general population (P=0.008, P=0.007, and P=0.044 respectively). HIF1-a alleles: general population > study groups, rs1951795C SNP (P=0.026 for benign lesions and P=0.0007 for thymomas), rs10873142T SNP (P=0.008 and P=0.001 respectively), rs12434438 A SNP (P=0.034 and P=0.0007) and rs2301113A SNP (P=0.027 and P=0.010). rs699947C polymorphism of VEGF-A: benign lesions > general population (P=0.012).ConclusionsThis is the first study investigating the angiogenetic polymorphisms in thymic benign lesions and TETs. SNPs analysis may represent a further asset in identification of patients who could benefit from anti-angiogenetic therapy.

Neuropilin-1 directs PDGFRα-entry into lung fibroblasts and signaling from very early endosomes.

Platelet-derived growth factor receptor-α (PDGFRα) is absolutely required for the development of secondary pulmonary alveolar septa. Our earlier observations indicated that PDGFRα resides intracellularly as well as on the plasma membrane of murine lung fibroblasts (LF). We have examined how neuropilin-1 (Nrp1), a surface receptor without kinase activity, regulates the intracellular trafficking of PDGFRα in LF obtained from mice, some bearing a targeted deletion of Nrp1 in myofibroblasts. Using the proximity ligation assay, we observed that PDGFRα and Nrp1 colocalized in both early antigen-1 (EEA1) containing sorting endosomes and with adaptor protein containing a pleckstrin homology domain and a phosphotyrosine-binding domain-1 (APPL1) in very early endosomes (VEE). These findings were confirmed using live-cell imaging, which demonstrated that recently internalized PDGFRα was observed in Rab5-containing vesicles residing within 100 nm of the plasma membrane. Nrp1 deletion reduced the phosphorylation of Akt (protein kinase B), the major downstream target of PDGFRα, and limited accumulation of inositol-3 phosphates in APPL1-containing endosomes after exposure to PDGFA. PDGFRα co-immunoprecipitated with APPL1, indicating that PDGFRα enters VEE. Targeted deletion of Nrp1 or APPL1-depletion in control LF reduced the activity of an Akt1 biosensor following stimulation with PDGFA. Our findings demonstrate that Nrp1 enhances the entry of PDGFRα into APPL1 containing VEE and that APPL1 enhances PDGFRα signaling. Therefore, Nrp1 promotes endosomal signaling by PDGFRα offering a potential mechanism to explain our prior observation that Nrp1 supports the formation of alveolar ducts and alveoli during secondary septation in mice.

Specific induction and long-term maintenance of high purity ventricular cardiomyocytes from human induced pluripotent stem cells.

Currently, cardiomyocyte (CM) differentiation methods require a purification step after CM induction to ensure the high purity of the cell population. Here we show an improved human CM differentiation protocol with which high-purity ventricular-type CMs can be obtained and maintained without any CM purification process. We induced and collected a mesodermal cell population (platelet-derived growth factor receptor-α (PDGFRα)-positive cells) that can respond to CM differentiation cues, and then stimulated CM differentiation by means of Wnt inhibition. This method reproducibly generated CMs with purities above 95% in several human pluripotent stem cell lines. Furthermore, these CM populations were maintained in culture at such high purity without any further CM purification step for over 200 days. The majority of these CMs (>95%) exhibited a ventricular-like phenotype with a tendency to structural and electrophysiological maturation, including T-tubule-like structure formation and the ability to respond to QT prolongation drugs. This is a simple and valuable method to stably generate CM populations suitable for cardiac toxicology testing, disease modeling and regenerative medicine.

FOXL1 Regulates Lung Fibroblast Function via Multiple Mechanisms.

Fibroblasts provide a structural framework for multiple organs and are essential for wound repair and fibrotic processes. Here, we demonstrate functional roles of FOXL1 (forkhead box L1), a transcription factor that characterizes the pulmonary origin of lung fibroblasts. We detected high FOXL1 transcripts associated with DNA hypomethylation and super-enhancer formation in lung fibroblasts, which is in contrast with fibroblasts derived from other organs. RNA in situ hybridization and immunohistochemistry in normal lung tissue indicated that FOXL1 mRNA and protein are expressed in submucosal interstitial cells together with airway epithelial cells. Transcriptome analysis revealed that FOXL1 could control a broad array of genes that potentiate fibroblast function, including TAZ (transcriptional coactivator with PDZ-binding motif)/YAP (Yes-associated protein) signature genes and PDGFRα (platelet-derived growth factor receptor-α). FOXL1 silencing in lung fibroblasts attenuated cell growth and collagen gel contraction capacity, underscoring the functional importance of FOXL1 in fibroproliferative reactions. Of clinical importance, increased FOXL1 mRNA expression was found in fibroblasts of idiopathic pulmonary fibrosis lung tissue. Our observations suggest that FOXL1 regulates multiple functional aspects of lung fibroblasts as a key transcription factor and is involved in idiopathic pulmonary fibrosis pathogenesis.

Hepatic Stellate Cell–Specific Platelet-Derived Growth Factor Receptor-α Loss Reduces Fibrosis and Promotes Repair after Hepatocellular Injury

Platelet-derived growth factor receptor (PDGFR)-α plays roles in cell survival, proliferation, and differentiation; however, its function in chronic liver injury sequelae, such as fibrosis, is unknown. Hepatic stellate cells (HSCs), the primary mediators of fibrosis, undergo activation, which entails differentiation to myofibroblasts, proliferation, migration, and collagen deposition, partially in response to PDGFs. To examine the role of PDGFR-α in HSCs, Lrat-Cre recombinase and Pdgfra-floxed mice were bred to generate Lrat-CrePdgfra-/- (knockout) animals, which were subjected to chronic liver injury through carbon tetrachloride treatment, bile duct ligation, and 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine. Although no major difference was observed after other types of liver injury, PDGFR-α loss in HSCs led to a significant albeit transient reduction in fibrosis after carbon tetrachloride injury, associated with increased HSC death and reduced migration. There was continued alleviation of hepatocellular injury in knockout mice despite ongoing carbon tetrachloride insult, associated with increased numbers of CD68 and F480 macrophages and increased clearance of damaged hepatocytes. Altogether our findings support a profibrotic role of PDGFR-α in HSCs during chronic liver injury invivo via regulation of HSC survival and migration and affect the immune microenvironment, especially macrophages in clearing dying hepatocytes. Thus, our study provides a preclinical foundation for the future testing of therapeutic PDGFR-α inhibition in hepatic fibrosis, especially in combination with other therapies.

296 Recombination efficiency and expression of fibroblast-specific Cre drivers in mouse skin

Cell-type specific genetic recombination is a powerful strategy for advancing understanding of cellular function in genetically-modified mouse models. This approach relies on cell-type specific gene promoters to drive genetic recombination in target cells. Although the utility of many cell-type specific promoters has been well characterized, thorough characterization of fibroblast-specific promoters is lacking. Therefore, we employed the mTmG two-color fluorescent reporter system to examine the genetic recombination efficiency and expression patterns of three fibroblast-specific promoters in mouse skin. mTmG mice express the red fluorescent protein tdTomato (mT) constitutively and ubiquitously. Genetic recombination catalyzed by Cre recombinase silences mT expression and induces expression of enhanced green fluorescent protein (mG). Thus, cells that express Cre recombinase appear green, while all other cells appear red. We generated mTmG mice that express Cre recombinase under the control of promoter elements in three fibroblast-specific genes 1) fibroblast specific protein-1 (FSP-1), 2) type Iα2 collagen (COL1A2), or 3) platelet-derived growth factor receptor-α (PDGFRα). Dorsal skin from mTmG/Cre positive and control mice were analyzed by immunofluorescence microscopy. Surprisingly, mTmG/FSP-1 Cre mice exhibited recombination largely in keratinocytes throughout all the layers of the epidermis and follicular epithelium. Recombination was also observed in scattered fibroblast-like cells in the dermis. mTmG/COL1A2 Cre mice displayed recombination that was specific for dermal cells with fibroblast-like morphology throughout the interstitial dermis and in dermal papillae. mTmG/PDGFRα Cre mice displayed recombination that was similar to that of COL1A2-driven recombination, although the number of positive dermal cells and the intensity of mG expression was approximately five-fold greater. These data provide a foundation for the use of Cre drivers to study fibroblast gene expression in genetically-modified mouse models.

Identification and classification of interstitial cells in the mouse renal pelvis.

Platelet-derived growth factor receptor-α (PDGFRα) is a novel biomarker along with smooth myosin heavy chain for the pacemaker cells (previously termed 'atypical' smooth muscle cells) in the murine and cynomolgus monkey pelvis-kidney junction. PDGFRα+ cells present in adventitial and urothelial layers of murine renal pelvis do not express smooth muscle myosin heavy chain (smMHC) but are in close apposition to nerve fibres. Most c-Kit+ cells in the renal pelvis are mast cells. Mast cells (CD117+ /CD45+ ) are more abundant in the proximal renal pelvis and pelvis-kidney junction regions whereas c-Kit+ interstitial cells (CD117+ /CD45- ) are found predominantly in the distal renal pelvis and ureteropelvic junction. PDGFRα+ cells are distinct from c-Kit+ interstitial cells. A subset of PDGFRα+ cells express the Ca2+ -activated Cl- channel, anoctamin-1, across the entire renal pelvis. Spontaneous Ca2+ transients were observed in c-Kit+ interstitial cells, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using mice expressing genetically encoded Ca2+ sensors. Rhythmic contractions of the renal pelvis transport urine from the kidneys into the ureter. Specialized pacemaker cells, termed atypical smooth muscle cells (ASMCs), are thought to drive the peristaltic contractions of typical smooth muscle cells (TSMCs) in the renal pelvis. Interstitial cells (ICs) in close proximity to ASMCs and TSMCs have been described, but the role of these cells is poorly understood. The presence and distributions of platelet-derived growth factor receptor-α+ (PDGFRα+ ) ICs in the pelvis-kidney junction (PKJ) and distal renal pelvis were evaluated. We found PDGFRα+ ICs in the adventitial layers of the pelvis, the muscle layer of the PKJ and the adventitia of the distal pelvis. PDGFRα+ ICs were distinct from c-Kit+ ICs in the renal pelvis. c-Kit+ ICs are a minor population of ICs in murine renal pelvis. The majority of c-Kit+ cells were mast cells. PDGFRα+ cells in the PKJ co-expressed smooth muscle myosin heavy chain (smMHC) and several other smooth muscle gene transcripts, indicating these cells are ASMCs, and PDGFRα is a novel biomarker for ASMCs. PDGFRα+ cells also express Ano1, which encodes a Ca2+ -activated Cl- conductance that serves as a primary pacemaker conductance in ICs of the GI tract. Spontaneous Ca2+ transients were observed in c-Kit+ ICs, smMHC+ PDGFRα cells and smMHC- PDGFRα cells using genetically encoded Ca2+ sensors. A reporter strain of mice with enhanced green fluorescent protein driven by the endogenous promotor for Pdgfra was shown to be a powerful new tool for isolating and characterizing the phenotype and functions of these cells in the renal pelvis.

Severe paraneoplastic hypoglycemia due to a non-islet cell tumor in a patient with an advanced gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract, mainly localized in the stomach. Most GIST derive from mutations in tyrosine kinase receptors (KIT) or platelet-derived growth factor receptor-α (PDGFRA). GISTs are rarely associated with paraneoplastic hypoglycemia caused by non-β-cells tumor. This syndrome, defined non-islet cell tumor hypoglycemia (NICTH), arises from excess tumor production of insulin-like growth factor. We describe a 67-year-old female with severe NICTH secondary to an advanced and metastatic GIST.

Oligodendrogenesis and Myelin Formation in the Forebrain Require Platelet-derived Growth Factor Receptor-alpha

The platelet-derived growth factor receptor-α (PDGFRα) principally mediates growth factor signals in oligodendroglial progenitors and is involved in oligodendrogenesis and myelinogenesis in the developing spinal cord. However, the role of PDGFRα in the developing forebrain remains relatively unknown. We established a conditional knockout mouse for the Pdgfra gene (N-PRα-KO) using a Nestin promoter/enhancer-driven Cre recombinase and examined forebrain development. The expression of PDGFRα was efficiently suppressed in the Olig2+ cells in N-PRα-KO mice. In these mice, Olig2+ cells were slightly decreased during embryonic periods. The decrease was particularly striking during the postnatal period. The commitment of Pdgfra-inactivated Olig2+ cells to Sox10+ oligodendroglial-lineage was largely suppressed. Surviving Olig2+ cells and Sox10+ cells were distributed widely in the N-PRα-KO mouse brain, similarly to those in control mice until the early neonatal period. After that, these cells were drastically depleted in the forebrain during the second postnatal week. The brains of N-PRα-KO mice were severely hypomyelinated, and these mice died on approximately P17 with motor disturbances. Disturbed axonal fibers and extensively aberrant vascular formations appeared in the postnatal N-PRα-KO mouse brains. After the defective PDGFRα signal in the forebrain, these phenotypes were clearly different from those in the spinal cord that showed defective populations expansion and migration of oligodendroglial lineage and premature myelination, as previously described. In contrast, areas of severe hypomyelination were common to both anatomical sites. PDGFRα was critically involved in the myelination of the forebrain and may differently regulate oligodendroglial lineage between the forebrain and spinal cord.

Platelet-derived Growth Factor-α and Neuropilin-1 Mediate Lung Fibroblast Response to Rigid Collagen Fibers.

During pulmonary secondary alveolar septation, the rudimentary distal saccule subdivides by extending tissue sheets into the saccular air space, creating alveoli, which open into the alveolar duct. The sheets originate from saccular mesenchymal cells, which contain α-SMA (αSMA [ACTA2]) and abut elastic fibers (myofibroblasts [MF]), characteristics that are shared by cells that subsequently occupy the secondary septal tips. During elongation, collagen fibers are positioned to provide a scaffold for translocating septal mesenchymal cells. We hypothesized that collagen fibers direct the migration, orientation, and location of MFs during septal elongation. To address this hypothesis, we examined how electrospun collagen fibers direct the migration of fibroblasts bearing targeted deletions of PDGFRα (platelet-derived growth factor receptor-α) or Nrp1 (neuropilin-1), after their isolation from lungs that exhibit reduced secondary septation. We observed that deletion of either gene reduced Rac1 activation and the speed of migration of lung fibroblasts (LF) along electrospun fibers. The deletions did not reduce the proportion of LF that displayed collagen-binding integrins and increased the proportion of LF bearing activated β1-integrin. LF bearing the PDGFRα deletion failed to localize focal adhesions over electrospun fibers, suggesting that they may not appropriately sense and respond to regionally increased stiffness near the fibers. In lungs of mice bearing the PDGFRα deletion, collagen fibers are delocalized from ACTA2-containing MF, and their orientation deviated from the plane of the alveolar walls. Diminished PDGFRα or Nrp1 reduces LF localization to stiffer regions of fibrillar collagen substrates, suggesting that signaling through these receptors enables responsiveness to regional differences in extracellular matrix rigidity.

CD90+CD146+ identifies a pulmonary mesenchymal cell subtype with both immune modulatory and perivascular-like function in postnatal human lung.

Our understanding of mesenchymal cell subsets and their function in human lung affected by aging and in certain disease settings remains poorly described. We use a combination of flow cytometry, prospective cell-sorting strategies, confocal imaging, and modeling of microvessel formation using advanced microfluidic chip technology to characterize mesenchymal cell subtypes in human postnatal and adult lung. Tissue was obtained from patients undergoing elective surgery for congenital pulmonary airway malformations (CPAM) and other airway abnormalities including chronic obstructive pulmonary disease (COPD). In microscopically normal postnatal human lung, there was a fivefold higher mesenchymal compared with epithelial (EpCAM+) fraction, which diminished with age. The mesenchymal fraction composed of CD90+ and CD90+CD73+ cells was enriched in CXCL12 and platelet-derived growth factor receptor-α (PDGFRα) and located in close proximity to EpCAM+ cells in the alveolar region. Surprisingly, alveolar organoids generated from EpCAM+ cells supported by CD90+ subset were immature and displayed dysplastic features. In congenital lung lesions, cystic air spaces and dysplastic alveolar regions were marked with an underlying thick interstitium composed of CD90+ and CD90+PDGFRα+ cells. In postnatal lung, a subset of CD90+ cells coexpresses the pericyte marker CD146 and supports self-assembly of perfusable microvessels. CD90+CD146+ cells from COPD patients fail to support microvessel formation due to fibrinolysis. Targeting the plasmin-plasminogen system during microvessel self-assembly prevented fibrin gel degradation, but microvessels were narrower and excessive contraction blocked perfusion. These data provide important new information regarding the immunophenotypic identity of key mesenchymal lineages and their change in a diverse setting of congenital lung lesions and COPD.

Establishment of a stem Leydig cell line capable of 11-ketotestosterone production.

The deficiency or insufficiency of androgen can trigger a range of reproductive diseases as well as other symptoms. Stem Leydig cells (SLCs) are critical for the formation and maintenance of a functional androgen-producing cell (Leydig cell, LC) population throughout adult male life. However, to date, our knowledge about SLCs is poor. Here we report the derivation and characterisation of a clonal stem LC line (designated as TSL) capable of 11- ketotestosterone (11-KT) production from a 3-month-old Nile tilapia (Oreochromis niloticus) testis. The cells retained stable proliferation after 77 generations with normal karyotype and growth factor dependency. They expressed platelet-derived growth factor receptor-α (pdgfrα), nestin and chicken ovalbumin upstream promoter transcription factor II (coup-tfIIa), which are characteristic of SLCs. Upon induction in defined medium, TSLs could undergo differentiation into steroidogenically active LCs and produce 11-KT. When implanted into recipient Nile tilapia testes from which endogenous LCs had been eliminated by ethane dimethanesulphonate (EDS) treatment, the PKH26-labelled TSLs could colonise the interstitium, subsequently express steroidogenic genes and restore 11-KT production. Taken together, our data suggest that TSLs possess the ability of continuous proliferation and potential of differentiation into functional LCs invitro and invivo. To the best of our knowledge TSL might represent the first stem LC line capable of 11-KT production to date. Our study may offer new opportunities for investigating the self-renewal of SLCs and steroidogenesis invitro, and provide an invaluable invitro model for investigating endocrine disruptors.