Search

The glycosylphosphatidylinositol (GPI)‐anchored protein cluster of differentiation 109 (CD109) is expressed on many human cell types and modulates the transforming growth factor β (TGF‐β) signaling network. CD109 belongs to the alpha‐macroglobulin family of proteins, known for their protease‐triggered conformational changes. However, the effect of proteolysis on CD109 and its conformation are unknown. Here, we investigated the interactions of CD109 with proteases. We found that a diverse selection of proteases cleaved peptide bonds within the predicted bait region of CD109, inducing a conformational change that activated the thiol ester of CD109. We show CD109 was able to conjugate proteases with this thiol ester and decrease their activity toward protein substrates, demonstrating that CD109 is a protease inhibitor. We additionally found that CD109 has a unique mechanism whereby its GPI‐anchored macroglobulin 8 (MG8) domain dissociates during its conformational change, allowing proteases to release CD109 from the cell surface by a precise mechanism and not unspecific shedding. We conclude that proteolysis of the CD109 bait region affects both its structure and location, and that interactions between CD109 and proteases may be important to understanding its functions, for example, as a TGF‐β co‐receptor. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 TGFβRII 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Transforming growth factor‐β (TGF‐β) superfamily signaling via their cognate receptors is frequently modified by TGF‐β 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 TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto‐1, MuSK, and RGMs. Dysregulation of these co‐receptors can lead to altered TGF‐β 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‐β superfamily co‐receptors on TGF‐β 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. Key Findings: TGF‐β superfamily co‐receptors primarily modify ligand interactions with their cognate receptor complexes to enhance or suppress downstream SMAD signaling.Many TGF‐β superfamily co‐receptors are secreted or shed from the cell surface to further modify surface receptor signaling via ligand sequestration.Dysregulation of TGF‐β superfamily co‐receptors contribute to the pathophysiology of many cancers and a rational for the pharmacological targeting of these co‐receptors is on the rise. [ABSTRACT FROM AUTHOR]

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‐β 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‐β activation in the presence of LTBP1. Therefore, these data suggest the significance of the regulation of TGF‐β 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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‐β1 (TGF‐β1) 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‐β1‐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. [ABSTRACT FROM AUTHOR]

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)‐β receptors and negatively regulates TGF‐β 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Excessive extracellular matrix deposition that occurs in many fibrotic skin disorders such as hypertrophic scarring and scleroderma is often associated with hypoxia. CD109 is a novel TGF- β co-receptor and TGF- β antagonist shown to inhibit TGF- β-induced extracellular matrix protein production in vitro. We examined whether CD109 is able to regulate extracellular matrix deposition under low oxygen tension in vivo using transgenic mice overexpressing CD109 in the epidermis. By creating dorsal bipedicle skin flaps with centrally located excisional wounds in these mice and their wild-type littermates, we generated a novel murine hypoxic wound model. Mice were sacrificed on 7 or 14 days post-wounding, and tissues were harvested for histological and biochemical analysis. Hypoxic wounds in both transgenic and wild-type mice showed increased levels of HIF-1 α and delayed wound closure, validating this model in mice. Hypoxic wounds in CD109 transgenic mice demonstrated decreased collagen type 1 and fibronectin expression, and reduced dermal thickness on day 7 post-wounding as compared to those in wild-type mice and to non-hypoxic control wounds. These results suggest that CD109 decreases extracellular matrix production and fibrotic responses during hypoxic wound healing. Manipulating CD109 levels may have potential therapeutic value for the treatment of fibrotic skin disorders associated with poor oxygen delivery. [ABSTRACT FROM AUTHOR]

Transforming growth factor (TGF)-β is an important cytokine that negatively regulates keratinocyte proliferation. Deregulation of TGF-β signalling has been reported in psoriasis, where despite increased expression of TGF-β, psoriatic keratinocytes continue to hyperproliferate. Recently, we have identified CD109, a glycosyl phosphatidylinositol (GPI)-anchored protein, as a novel co-receptor and negative regulator of TGF-β signalling. In the current work, we demonstrate that release of CD109 from the cell surface or the addition of CD109 protein results in downregulation of TGF-β signalling and TGF-β receptor expression in human keratinocytes. Moreover, these effects are associated with an increase in phospho-STAT3 levels, enhanced total STAT3 and Bcl-2 expression and an increase in cell growth and survival, suggesting that released/soluble CD109 is able to induce molecular changes that are known to occur in psoriasis. Analysis of CD109 expression in psoriasis patients reveals that CD109 protein expression is markedly decreased in psoriatic epidermis as compared to adjacent uninvolved skin. In contrast, CD109 mRNA expression is unchanged in psoriatic plaques in comparison with normal skin. This raises a possibility that CD109 protein release is enhanced in psoriatic keratinocytes. Furthermore, psoriatic epidermis displays decreased expression of TGF-β receptors, consistent with the results obtained in vitro in keratinocytes with CD109 release or addition of CD109 recombinant protein. Together our findings suggest that aberrant CD109 release from the cell surface in human keratinocytes may induce molecular changes that are usually observed in psoriasis and may explain TGF-β receptor downregulation and decrease in TGF-β signalling in psoriasis. [ABSTRACT FROM AUTHOR]

Bladder cancer is one of the most common malignant diseases. Since a high-rate of recurrence is a serious problem for early stage urothelial carcinomas, new strategies for the management of recurrent urothelial carcinomas have been explored. CD109 is a glycosylphosphatidylinositol-anchored glycoprotein and is expressed in various cancer tissues, mainly squamous cell carcinomas. CD109 negatively controls transforming growth factor (TGF)-β/Smad signaling in vitro. In this study, we analyzed the clinical significance of CD109 expression in bladder cancer using immunohistochemistry. Of 156 urothelial carcinoma tissues, 69.9% were positive for CD109, whereas CD109 was not expressed in seven normal bladder epithelia. CD109 expression was significantly higher in non-muscle-invasive (pTa+pT1) or low-grade (G1+G2) tumors than in muscle-invasive (pT2-4) or high-grade (G3) tumors, and was associated with cancer-specific survival. Simultaneous immunostaining of CD109 and phosphorylated Smad2 showed an inverse immunoreactivity relationship between the two, suggesting that CD109 inhibits TGF-β/Smad signaling in tumor tissues. Interestingly, CD109 was found to be highly expressed in the basal layer of non-invasive urothelial carcinomas, and the expression pattern was similar to that of CD44, a marker of cancer stem cells. These findings suggest that CD109 is involved in bladder tumorigenesis and is a potential target for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Breast cancer can be classified into several subtypes based on gene expression profiling. Basal-like breast carcinoma (BLC) has a triple negative phenotype, that is, the subtype lacks the estrogen receptor (ER), progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2). It has been recently reported that CD109, a glycosylphosphatidylinositol (GPI)-anchored cell surface protein, is a new breast myoepithelial marker. In the present study CD109 expression was investigated in invasive ductal carcinomas (IDC) of the breast on immunohistochemistry. Eighty-eight formalin-fixed, paraffin-embedded breast carcinoma sections were immunostained with anti-CD109, anti-cytokeratin 5/6 (CK5/6), anti-calponin, anti-vimentin and anti-p63 antibodies. CD109 expression was detected in 18 of 30 basal-like breast carcinomas (BLC) but not in other types of 53 IDC (non-BLC) that were positive for ER, PgR and/or HER2. The percentage of CD109-positive tissues (60%) in BLC was similar to that of CK5/6 (63%) and higher than that of other myoepithelial markers including p63 (23%), calponin (33%) and vimentin (33%). Statistical analysis indicated that the CD109-positive group in BLC, but not the CK5/6-positive group in BLC, was associated with reduced fat invasion ( P < 0.05). These findings indicate that CD109 is a useful diagnostic marker for BLC and that CD109 expression may affect biological properties of cancer cells. [ABSTRACT FROM AUTHOR]

CD109 is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein, which is a member of the α2-macroglobulin/C3, C4, C5 family of thioester-containing proteins. It has been reported that CD109 is expressed in a subset of hematopoietic cells, endothelial cells and several kinds of human tumors. Herein it is reported that the CD109 protein is preferentially expressed in lung squamous cell carcinomas compared with other types of lung carcinoma including adenocarcinomas, large cell carcinomas and small cell carcinomas. Immunohistochemical staining of surgically resected lung specimens using an anti-CD109 antibody detected CD109 expression in basal cells of bronchial and bronchiolar epithelia and myoepithelial cells of bronchial secretary glands, but not in bronchial and bronchiolar apical epithelial cells and alveolar epithelial cells. Furthermore, the CD109 immunoreactivity was observed in squamous cell carcinomas at a high frequency compared with other types of lung carcinoma. Although the detailed function of CD109 protein is unclear, these results suggest that CD109 expression may play a role in the development of lung squamous cell carcinoma. [ABSTRACT FROM AUTHOR]

The CD109 gene encodes a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Herein it is shown that CD109 is highly expressed in myoepithelial cells of mammary, salivary, and lacrimal glands; and in prostate basal cells. The anti-CD109 antibody generated by the authors was available for formalin-fixed paraffin section, and it strongly stained myoepithelial cells and basal cells but not ductal, acinar, and secretory cells in these glands. CD109 expression was negative in examined breast ductal carcinomas and prostate adenocarcinomas. These findings indicate that CD109 is a useful marker for the diagnosis of invasive breast and prostate carcinomas. [ABSTRACT FROM AUTHOR]