Epicardial deletion of Sox9 leads to myxomatous valve degeneration and identifies Cd109 as a novel gene associated with valve development.

Epicardial-derived cells (EPDCs) are involved in the regulation of myocardial growth and coronary vascularization and are critically important for proper development of the atrioventricular (AV) valves. SOX9 is a transcription factor expressed in a variety of epithelial and mesenchymal cells in the developing heart, including EPDCs. To determine the role of SOX9 in epicardial development, an epicardial-specific Sox9 knockout mouse model was generated. Deleting Sox9 from the epicardial cell lineage impairs the ability of EPDCs to invade both the ventricular myocardium and the developing AV valves. After birth, the mitral valves of these mice become myxomatous with associated abnormalities in extracellular matrix organization. This phenotype is reminiscent of that seen in humans with myxomatous mitral valve disease (MVD). An RNA-seq analysis was conducted in an effort to identify genes associated with this myxomatous degeneration. From this experiment, Cd109 was identified as a gene associated with myxomatous valve pathogenesis in this model. Cd109 has never been described in the context of heart development or valve disease. This study highlights the importance of SOX9 in the regulation of epicardial cell invasion-emphasizing the importance of EPDCs in regulating AV valve development and homeostasis-and reports a novel expression profile of Cd109, a gene with previously unknown relevance in heart development.

CD109 on Dendritic Cells Regulates Airway Hyperreactivity and Eosinophilic Airway Inflammation.

Asthma is a chronic airway inflammatory disease characterized by airway hyperreactivity (AHR) and eosinophilic airway inflammation. Dendritic cells (DCs) are essential for the development of asthma via presenting allergens, causing T-helper cell type 2 (Th2) skewing and eosinophil inflammation. Recent studies have revealed that CD109, a glycosylphosphatidylinositol-anchored glycoprotein, is involved in the pathogenesis of inflammatory diseases such as rheumatoid arthritis and psoriasis. However, no study has addressed the role of CD109 in asthma. This study sought to address the role of CD109 on DCs in the development of AHR and allergic inflammation. CD109-deficient mice (CD109-/-) were sensitized with house dust mite or ovalbumin and compared with wild-type mice for induction of AHR and allergic inflammation. CD109-deficient mice had reduced AHR and eosinophilic inflammation together with lower Th2 cytokine expression compared with wild-type mice. Interestingly, CD109 expression was induced in lung conventional DC2s (cDC2s), but not lung cDC1s, upon allergic challenge. Lung cDC2s from CD109-/- mice had a poor ability to induce cytokine production in ex vivo DC-T cell cocultures with high expression of RUNX3 (runt-related transcription factor 3), resulting in suppression of Th2 differentiation. Adoptive transfer of bone marrow-derived CD109-/- DCs loaded with house dust mite failed to develop AHR and eosinophilic inflammation. Finally, administration of monoclonal anti-CD109 antibody reduced airway eosinophils and significantly decreased AHR. Our results suggest the involvement of CD109 in asthma pathogenesis. CD109 is a novel therapeutic target for asthma.

H3K27 acetylation activated-CD109 evokes 5-fluorouracil resistance in gastric cancer via the JNK/MAPK signaling pathway.

Drug resistance is a considerable obstacle to gastric cancer (GC) treatment. The current work aimed to elucidate the functional mechanism of CD109 in 5-fluorouracil (5-FU) resistance in GC. In this study, we demonstrated that CD109 was extremely heightened in 5-FU-resistant GC cells. CD109 deficiency lessened the IC50 value, impaired cell viability and metastatic capability, and induced cell apoptosis after 5-FU treatment in cells. In addition, we found that PAX5 bound p300 increased the enrichment of H3K27ac at the promoter region of the CD109 gene, which resulted in the upregulation of CD109 in GC. Moreover, we also revealed that CD109 triggered 5-FU resistance via activating the JNK/MAPK signaling. Blockage of JNK/MAPK signaling using JNK inhibitor, SP600125, abolished CD109 upregulation-induced changes of IC50 values, cell viability, metastasis and apoptosis in NCI-N87/5-FU and SNU-1/5-FU cells. Importantly, CD109 silencing enhanced the therapeutic efficacy of 5-FU, leading to reduced tumor growth in vivo. In conclusion, our results unveiled that H3K27 acetylation activated-CD109 enhanced 5-FU resistance of GC cells via modulating the JNK/MAPK signaling pathway, which might provide an attractive therapeutic target for GC.

CD109 Promotes Drug Resistance in A2780 Ovarian Cancer Cells by Regulating the STAT3-NOTCH1 Signaling Axis.

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy owing to relapse caused by resistance to chemotherapy. We previously reported that cluster of differentiation 109 (CD109) expression is positively correlated with poor prognosis and chemoresistance in patients with EOC. To further explore the role of CD109 in EOC, we explored the signaling mechanism of CD109-induced drug resistance. We found that CD109 expression was upregulated in doxorubicin-resistant EOC cells (A2780-R) compared with that in their parental cells. In EOC cells (A2780 and A2780-R), the expression level of CD109 was positively correlated with the expression level of ATP-binding cassette (ABC) transporters, such as ABCB1 and ABCG2, and paclitaxel (PTX) resistance. Using a xenograft mouse model, it was confirmed that PTX administration in xenografts of CD109-silenced A2780-R cells significantly attenuated in vivo tumor growth. The treatment of CD109-overexpressed A2780 cells with cryptotanshinone (CPT), a signal transducer and activator of transcription 3 (STAT3) inhibitor, inhibited the CD109 overexpression-induced activation of STAT3 and neurogenic locus notch homolog protein 1 (NOTCH1), suggesting a STAT3-NOTCH1 signaling axis. The combined treatment of CD109-overexpressed A2780 cells with CPT and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT), a NOTCH inhibitor, markedly abrogated PTX resistance. These results suggest that CD109 plays a key role in the acquisition of drug resistance by activating the STAT3-NOTCH1 signaling axis in patients with EOC.

TGF-ß superfamily co-receptors in cancer.

Transforming growth factor-ß (TGF-ß) superfamily signaling via their cognate receptors is frequently modified by TGF-ß superfamily co-receptors. Signaling through SMAD-mediated pathways may be enhanced or depressed depending on the specific co-receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co-receptors from the membrane to generate soluble forms that are often antagonistic to the membrane-bound receptors. The co-receptors discussed here include TßRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto-1, MuSK, and RGMs. Dysregulation of these co-receptors can lead to altered TGF-ß superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF-ß superfamily co-receptors on TGF-ß superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co-receptors.

Novel Regulators of Retina Neovascularization: A Proteomics Approach.

The purpose of this study was to identify proteins that regulate vascular remodeling in an ROP mouse model. Pups were subjected to fluctuating oxygen levels and retinas sampled during vessel regression (PN12) or neovascularization (PN17) for comparative SWATH-MS proteomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We developed a human retinal endothelial cell (HREC) ROP correlate to validate the expression of retina neovascular-specific markers. A total of 5191 proteins were identified in OIR retinas with 498 significantly regulated in elevated oxygen and 345 after a return to normoxia. A total of 122 proteins were uniquely regulated during vessel regression and 69 during neovascularization (FC ≥ 1.5; p ≤ 0.05), with several validated by western blot analyses. Expressions of 56/69 neovascular-specific proteins were confirmed in hypoxic HRECs with 23 regulated in the same direction as OIR neovascular retinas. These proteins control angiogenesis-related processes including matrix remodeling, cell migration, adhesion, and proliferation. RNAi and transfection overexpression studies confirmed that VASP and ECH1, showing the highest levels in hypoxic HRECs, promoted human umbilical vein (HUVEC) and HREC cell proliferation, while SNX1 and CD109, showing the lowest levels, inhibited their proliferation. These proteins are potential biomarkers and exploitable intervention tools for vascular-related disorders. The proteomics data set generated has been deposited to the ProteomeXchange/iProX Consortium with the Identifier:PXD029208.

A first WHO reference reagent for the detection of anti-human platelet antigen-15b.

BACKGROUND AND OBJECTIVES: Alloantibodies to human platelet antigen-15b (anti-HPA-15b) have been detected in mothers with foetal-neonatal alloimmune thrombocytopenia and in multiply transfused patients. Assays used to detect this antibody, which aids in disease diagnosis, can be unreliable and vary in sensitivity. The objective was to generate a stable, lyophilized anti-HPA-15b preparation and evaluate its suitability as a World Health Organization (WHO) reference reagent for use in the quality control of platelet alloantibody detection assays. Results from an international collaborative study to evaluate the preparation were used to assign a minimum potency at which laboratories can be expected to detect the antibody. MATERIALS AND METHODS: Recalcified plasma containing anti-HPA-15b was aliquotted, lyophilized and coded 18/220. Twenty-five laboratories in 16 countries tested doubling dilutions of the reconstituted material in glycoprotein-specific assays such as the monoclonal antibody-specific immobilization of platelet antigen assay and reported the last positive (or endpoint) dilution. RESULTS: Twenty-four laboratories (96%) detected antibodies with HPA-15b specificity in preparation 18/220. Reported endpoint dilutions were normally distributed with a modal dilution of 1 in 16 and ranged from 1 in 2 to 1 in 128. Only two laboratories (8%) failed to detect anti-HPA-15b at 1 in 8 dilution. CONCLUSIONS: When diluted 1 in 8, most laboratories detected anti-HPA-15b in preparation 18/220 using HPA-15bb platelets but not with HPA-15aa platelets. The participants agreed this to be an appropriate dilution for assignment as the minimum potency. In October 2020, the WHO Expert Committee on Biological Standardization approved 18/220 as an International Reference Reagent.

AAV-mediated expression of galactose-1-phosphate uridyltransferase corrects defects of galactose metabolism in classic galactosemia patient fibroblasts.

Classic galactosemia (CG) is a rare disorder of autosomal recessive inheritance. It is caused predominantly by point mutations as well as deletions in the gene encoding the enzyme galactose-1-phosphate uridyltransferase (GALT). The majority of the more than 350 mutations identified in the GALT gene cause a significant reduction in GALT enzyme activity resulting in the toxic buildup of galactose metabolites that in turn is associated with cellular stress and injury. Consequently, developing a therapeutic strategy that reverses both the oxidative and ER stress in CG cells may be helpful in combating this disease. Recombinant adeno-associated virus (AAV)-mediated gene therapy to restore GALT activity offers the potential to address the unmet medical needs of galactosemia patients. Here, utilizing fibroblasts derived from CG patients we demonstrated that AAV-mediated augmentation of GALT protein and activity resulted in the prevention of ER and oxidative stress. We also demonstrate that these CG patient fibroblasts exhibit reduced CD109 and TGFßRII protein levels and that these effectors of cellular homeostasis could be restored following AAV-mediated expression of GALT. Finally, we show initial in vivo proof-of-concept restoration of galactose metabolism in a GALT knockout mouse model following treatment with AAV-GALT.

Elevation of CD109 promotes metastasis and drug resistance in lung cancer via activation of EGFR-AKT-mTOR signaling.

Lung cancer is the most commonly diagnosed cancer worldwide, and metastasis in lung cancer is the leading cause of cancer-related deaths. Thus, understanding the mechanism of lung cancer metastasis will improve the diagnosis and treatment of lung cancer patients. Herein, we found that expression of cluster of differentiation 109 (CD109) was correlated with the invasive and metastatic capacities of lung adenocarcinoma cells. CD109 is upregulated in tumorous tissues, and CD109 overexpression was associated with tumor progression, distant metastasis, and a poor prognosis in patient with lung adenocarcinoma. Mechanistically, expression of CD109 regulates protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling via its association with the epidermal growth factor receptor (EGFR). Inhibition of CD109 decreases EGFR phosphorylation, diminishes EGF-elicited activation of AKT/mTOR, and sensitizes tumor cells to an EGFR inhibitor. Taken together, our results show that CD109 is a potential diagnostic and therapeutic target in lung cancer patients.

CD109 regulates in vivo tumor invasion in lung adenocarcinoma through TGF-ß signaling.

Stromal invasion is considered an important prognostic factor in patients with lung adenocarcinoma. The mechanisms underlying the formation of tumor stroma and stromal invasion have been studied in the lung; however, they are still unclear. CD109 is a glycosylphosphatidylinositol-anchored glycoprotein highly expressed in several types of human malignant tumors including lung cancers. In this study, we investigated the in vivo functions of CD109 protein in malignant lung tumors. Initially, we identified an association between higher expression of CD109 protein in human lung adenocarcinoma and a significantly worse prognosis, according to immunohistochemical analysis. We also showed that CD109 deficiency significantly reduced the area of stromal invasive lesions in a genetically engineered CD109-deficient lung adenocarcinoma mouse model, which correlated with the results observed in human lung adenocarcinoma. Furthermore, we identified latent TGF-ß binding protein-1 (LTBP1) as a CD109-interacting protein using mass spectrometry and confirmed their interaction by co-immunoprecipitation. Importantly, increased CD109 expression enhanced stromal TGF-ß activation in the presence of LTBP1. Therefore, these data suggest the significance of the regulation of TGF-ß signaling through CD109 and LTBP1 interaction in tumor stroma and also reveal the importance of CD109 expression levels in promoting lung cancer cell proliferation, migration, and invasion, and thus predicting the outcome of patients suffering from lung adenocarcinoma. Therefore, CD109 protein could be a potential therapeutic target for this disease.

CD109 promotes the tumorigenic ability and metastatic motility of pancreatic ductal adenocarcinoma cells.

BACKGROUND: Accumulating evidence indicates that CD109, a glycosylphosphatidylinositol-anchored glycoprotein, is highly expressed in human epithelial carcinomas of multiple organs including the pancreas, but its functional role in carcinoma development has not yet been fully clarified. The aim of this study was to investigate the role of CD109 in the malignancy of pancreatic ductal adenocarcinoma (PDAC). METHODS: PDAC specimens of 145 cases were immunostained for CD109, and correlations between CD109 expression and clinicopathological conditions were analyzed. CD109 expression in PANC-1 cells, a PDAC-derived cell line, was decreased by siRNA or shRNA and its effect on the malignancy of PANC-1 cells was examined. RESULTS: Suppression of CD109 expression in PANC-1 cells resulted in reduction of in vitro cell motility and tumorigenicity in xenografts. Based on these results, we investigated the relationship between CD109 expression and metastasis of PDAC using tumor tissue specimens. Among 106 recurrent cases of 145 PDAC, there was a tendency for CD109-positive cases to be accompanied by distant metastasis. CONCLUSIONS: CD109 plays a critical role in the promotion of tumorigenic ability and cellular motility relating to metastasis of PDAC cells.

CD109 antigen-like gene is induced by ecdysone signaling and involved in the cellular immunity of Helicoverpa armigera.

Cellular immunity is evolutionarily conserved in invertebrates and vertebrates. In insects, cellular immune response is provided by the hemocytes, and its molecular mechanisms are currently not fully understood. Here, we identified a CD109 antigen-like gene (HaCD109) from Helicoverpa armigera which is highly expressed in the hemocytes of larvae. Stimulation by Escherichia coli and chromatography beads significantly upregulated HaCD109 expression. In vivo HaCD109 silencing significantly increased bacterial load in larval hemolymphs and reduced the hemocyte spread. 20-Hydroxyecdysone (20E) can induce HaCD109 expression through its receptors, EcR and USP. In vivo HaCD109 silencing nearly abolished 20E-induced bacterial clearance and hemocyte spread. These results suggested that HaCD109 plays an important role in cellular immunity, and the 20E-induced cellular immune response in H. armigera requires HaCD109 involvement. Our study contributes to the understanding of regulatory mechanisms for innate immune response and provides new insights into the interaction between innate immunity and steroid hormone signaling.

CD109 deficiency induces osteopenia with an osteoporosis-like phenotype in vivo.

Osteoporosis is a global public health problem that is increasing along with an aging population. A major determinant of osteoporosis is high bone turnover, which results from osteoclast activation. CD109 is a glycosylphosphatidylinositol-anchored glycoprotein, a deficiency that leads to a psoriasis-like skin inflammation in mice. Although the expression of CD109 has been reported in mouse pre-osteoclast cells, its function in osteoclasts in vivo remains largely unknown. To investigate the physiological role of CD109 in bone metabolism, we analyzed bones from wild-type and CD109-deficient adult mice. Micro-computed tomography analysis of the femur (thigh bone) showed that bone volume was lower in CD109-deficient mice than in wild-type mice. Bone histomorphometric analysis showed not only a reduction in bone volume but also an increase in bone turnover in CD109-deficient mice as compared with wild-type mice. Additionally, we measured serum levels of several markers of bone turnover and found a significant increase in the N-terminal telopeptide of type I collagen, a bone resorption marker, as well as alkaline phosphatase, a bone formation marker, in CD109-deficient mice. These results indicate that CD109 deficiency induces a high-turnover, osteoporosis-like phenotype, which suggests that CD109 plays a role in bone metabolism in vivo.

CD109 regulates the inflammatory response and is required for the pathogenesis of rheumatoid arthritis.

OBJECTIVE: The aim of this study was to investigate the role of CD109 in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs) and to evaluate its potential as a therapeutic target. METHODS: CD109 expression was examined in synovial tissues and FLSs from RA patients and collagen-induced arthritis (CIA) model mice. CD109-deficient mice were developed to evaluate the severity of CIA. Small interfering RNAs and a neutralising antibody against CD109 (anti-CD109) were designed for functional or treatment studies in RA FLSs and CIA. RESULTS: CD109 was found to be abundantly expressed in the synovial tissues from RA patients and CIA mice. CD109 expression in RA FLSs was upregulated by inflammatory stimuli, such as interleukin-1ß and tumour necrosis factor-α. Silencing of CD109 or anti-CD109 treatment reduced proinflammatory factor production, cell migration, invasion, chemoattractive potential and osteoclast differentiation, thereby reducing the deleterious inflammatory response of RA FLSs in vitro. Mice lacking CD109 were protected against arthritis in the CIA model. Anti-CD109 treatment prevented the onset and ameliorated the severity of CIA lesions. CONCLUSION: Our study uncovers an antiarthritic role for CD109 and suggests that CD109 inhibition might serve as a promising novel therapeutic strategy for RA.

CD200 Expression Marks a Population of Quiescent Limbal Epithelial Stem Cells with Holoclone Forming Ability.

One of the main challenges in limbal stem cell (LSC) biology and transplantation is the lack of definitive cell surface markers which can be used to identify and enrich viable LSCs. In this study, expression of 361 cell surface proteins was assessed in ex vivo expanded limbal epithelial cells. One marker, CD200 was selected for further characterization based on expression in a small subset of limbal epithelial cells (2.25% ± 0.69%) and reduced expression through consecutive passaging and calcium induced differentiation. CD200 was localized to a small population of cells at the basal layer of the human and mouse limbal epithelium. CD200+ cells were slow cycling and contained the majority of side population (SP) and all the holoclone forming progenitors. CD200+ cells displayed higher expression of LSCs markers including PAX6, WNT7A, CDH3, CK14, CK15, and ABCB5 and lower expression of Ki67 when compared to CD200- . Downregulation of CD200 abrogated the ability of limbal epithelial cells to form holoclones, suggesting an important function for CD200 in the maintenance and/or self-renewal of LSCs. A second marker, CD109, which was expressed in 56.29% ± 13.96% of limbal epithelial cells, was also found to co-localize with ΔNp63 in both human and mouse cornea, albeit more abundantly than CD200. CD109 expression decreased slowly through calcium induced cell differentiation and CD109+ cells were characterized by higher expression of Ki67, when compared to CD109- subpopulation. Together our data suggest that CD200 expression marks a quiescent population of LSCs with holoclone forming potential, while CD109 expression is associated with a proliferative progenitor phenotype. Stem Cells 2018;36:1723-1735.

Revealing the glioma cancer stem cell interactome, one niche at a time.

Glioblastoma (GBM) cancer stem cells (CSCs) are insidious. They extensively infiltrate brain tissue, resist radiotherapy and chemotherapy, and are thought to represent the ultimate drivers of disease progression. New research has identified CD109, a GPI-anchored protein, on a population of perivascular CSCs. Investigation of primary human tumour tissue suggests a role for CD109-expressing CSCs in the progression from low-grade to high-grade glioma, and animal modelling reveals a critical role for CD109 in the maintenance of the GBM CSC phenotype. Furthermore, CD109-expressing CSCs appear to drive the proliferation of adjacent non-stem tumour cells (NSTCs) in a rare example of CSC-NSTC cooperative interaction. With this Commentary, we highlight the newly revealed biology of CD109, and offer a synthesis of the published information on glioma CSCs in a variety of anatomical growth zones. We also discuss the landscape of interacting cells within GBM tumours, emphasizing the few reported examples of pro-tumourigenic, interactive tumour cell partnerships, as well as a variety of tumour cell-non-transformed neural cell interactions. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

CD109: a multifunctional GPI-anchored protein with key roles in tumor progression and physiological homeostasis.

CD109 is a glycosylphosphatidylinositol-anchored glycoprotein and a member of the α2 -macroglobulin/C3,C4,C5 family of thioester-containing proteins first identified as being expressed on blood cells, including activated T cells and platelets, and a subset of CD34 + bone marrow cells containing megakaryocyte progenitors. Although CD109 carries the biallelic platelet-specific alloantigen Gov, the physiological functions or roles of CD109 in human disease remain largely unknown. It was recently demonstrated that CD109 is expressed in many malignant tumors, including various squamous cell carcinomas and adenocarcinomas, and plays a role as a multifunctional coreceptor. CD109 reportedly associates with transforming growth factor (TGF)-ß receptors and negatively regulates TGF-ß signaling in keratinocytes. Additionally, CD109 is potentially related to signal transducer and activator of transcription-3 signaling and aberrant cell proliferation. In this review, we describe recent evidence of CD109-specific significance in malignant tumors shown in mouse models and human tissues. Furthermore, we discuss the physiological functions of CD109 in vitro and in vivo, including results of phenotype analyses of CD109-deficient mice exhibiting epidermal hyperplasia and osteopenia.

Curcumin mitigates the epithelial-to-mesenchymal transition in biliary epithelial cells through upregulating CD109 expression.

Biliary epithelial cells (BECs) can secrete bile and the epithelial-to-mesenchymal transition (EMT) of BECs can cause fibrosis or damage interlobular bile ducts, leading to chronic cholangiopathies, such as primary biliary cholangitis (PBC). Transforming growth factor-ß1 (TGF-ß1) is a potent inducer of the EMT while curcumin, a diarylheptanoid, can inhibit the EMT of hepatocytes in many liver diseases. However, the protection and underlying mechanisms of curcumin against the EMT of BECs have not been clarified. Herein, we show that curcumin treatment significantly mitigates the EMT of BECs in vitro and in vivo. Mechanistically, curcumin significantly attenuated the TGF-ß1-induced Smad and Hedgehog signaling, and upregulated CD109 expression in BECs. Collectively, these findings highlighted the therapeutic potential of curcumin to counteract the EMT process in PBC.

CD109 and squamous cell carcinoma.

Squamous cell carcinoma (SCC) is well-known for its high rate of metastasis with poor prognosis. CD109 is a glycosylphosphatidylinositol-anchored cell-surface glycoprotein. Recently, CD109 emerges as a potential biomarker and a therapeutic target for SCCs. Accumulating studies have reported that CD109 is highly expressed in human SCCs of multiple organs, and may contribute to the progression of SCCs. In this review, we summarized the findings on expression pattern of CD109 in SCCs, and discussed the molecular mechanisms underlying the roles of CD109 in pathogenesis of SCCs.

Significance of perivascular tumour cells defined by CD109 expression in progression of glioma.

In the progression of glioma, tumour cells often exploit the perivascular microenvironment to promote their survival and resistance to conventional therapies. Some of these cells are considered to be brain tumour stem cells (BTSCs); however, the molecular nature of perivascular tumour cells has not been specifically clarified because of the complexity of glioma. Here, we identified CD109, a glycosylphosphatidylinositol-anchored protein and regulator of multiple signalling pathways, as a critical regulator of the progression of lower-grade glioma (World Health Organization grade II/III) by clinicopathological and whole-genome sequencing analysis of tissues from human glioma. The importance of CD109-positive perivascular tumour cells was confirmed not only in human lower-grade glioma tissues but also in a mouse model that recapitulated human glioma. Intriguingly, BTSCs isolated from mouse glioma expressed high levels of CD109. CD109-positive BTSCs exerted a proliferative effect on differentiated glioma cells treated with temozolomide. These data reveal the significance of tumour cells that populate perivascular regions during glioma progression, and indicate that CD109 is a potential therapeutic target for the disease. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.