Release of TGFβig-h3 by gastric myofibroblasts slows tumor growth and is decreased with cancer progression

Cancer-associated fibroblasts influence Wnt/PCP signaling in gastric cancer cells by cytoneme-based dissemination of ROR2

Cancer-associated fibroblasts (CAFs) are a crucial component in the tumor microenvironment influencing cancer progression. Besides shaping the extracellular matrix, these fibroblasts provide signaling factors to facilitate tumor survival and alter tumor behavior. In gastric cancer, one crucial signaling pathway influencing invasion and metastasis is the Wnt/Planar Cell Polarity (PCP) signaling. The crucial PCP ligand in this context is WNT5A, which is produced by the CAFs, and gastric cancer cells react upon this signal by enhanced polarized migration. Why gastric cancer cells respond to this signal is still unclear, as their expression level for the central WNT5A receptor, ROR2, is very low. Here, we show that CAFs display long and branched filopodia that form an extensive, complex network engulfing gastric cancer cells, such as the gastric cancer cell line AGS. CAFs have a significantly higher expression level of ROR2 than normal gastric fibroblasts and AGS cells. By high-resolution imaging, we observe a direct transfer of fluorescently tagged ROR2 from CAF to AGS cells by signaling filopodia, known as cytonemes. Surprisingly, we find that the transferred ROR2 complexes can activate Wnt/JNK signaling in AGS cells. Consistently, blockage of ROR2 function in the CAFs leads to reduced paracrine Wnt/JNK signaling, cell polarization, and migration of the receiving AGS cells. Complementary, enhanced migration via paracrine ROR2 transfer was observed in a zebrafish in vivo model. These findings demonstrate a fresh role for cytoneme-mediated signaling in the tumor microenvironment. Cytonemes convey Wnt receptors from CAFs to gastric cancer cells, allowing them to respond to Wnt/PCP signals.

CCR9 initiates epithelial-mesenchymal transition by activating Wnt/β-catenin pathways to promote osteosarcoma metastasis

Background

Osteosarcoma (OS) patients with lung metastasis have poor prognoses, and effective therapeutic strategies for delaying or inhibiting the spread of lung metastasis from the primary OS site are lacking. Hence, it is critical to elucidate the underlying mechanisms of OS metastasis and to identify additional new effective treatment strategies for patients.

Methods

Differential expression and functional analyses were performed to identify key genes and relevant signaling pathways associated with OS lung metastasis. The expression of CCR9 in OS cell lines and tissues was measured by RT-qPCR, western blotting and immunohistochemistry. Cell migration and invasion were assessed by wound healing and Transwell Matrigel invasion assays, respectively. The regulatory relationship between CCR9 and the Wnt/β-catenin signaling pathway was further evaluated by rescue experiments.

Results

The expression of CCR9 was elevated in OS cell lines and patients with lung metastasis. CCR9 promoted MG63 and HOS cell migration and invasion by activating the Wnt/β-catenin signaling pathway. Furthermore, knockdown of CCR9 repressed epithelial–mesenchymal transition (EMT) by downregulating mesenchymal markers (N-cadherin and Vimentin) and EMT-associated transcription factors (twist and snail) and upregulating an epithelial marker (E-cadherin).

Conclusions

Our findings suggest that CCR9 promotes EMT by activating Wnt/β-catenin pathways to promote OS metastasis. CCR9 may be a promising therapeutic target to inhibit lung metastasis and serve as a novel prognostic marker for OS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02320-0.

Transcriptional landscape of the embryonic chicken Müllerian duct

Background

Müllerian ducts are paired embryonic tubes that give rise to the female reproductive tract in vertebrates. Many disorders of female reproduction can be attributed to anomalies of Müllerian duct development. However, the molecular genetics of Müllerian duct formation is poorly understood and most disorders of duct development have unknown etiology. In this study, we describe for the first time the transcriptional landscape of the embryonic Müllerian duct, using the chicken embryo as a model system. RNA sequencing was conducted at 1 day intervals during duct formation to identify developmentally-regulated genes, validated by in situ hybridization.

Results

This analysis detected hundreds of genes specifically up-regulated during duct morphogenesis. Gene ontology and pathway analysis revealed enrichment for developmental pathways associated with cell adhesion, cell migration and proliferation, ERK and WNT signaling, and, interestingly, axonal guidance. The latter included factors linked to neuronal cell migration or axonal outgrowth, such as Ephrin B2, netrin receptor, SLIT1 and class A semaphorins. A number of transcriptional modules were identified that centred around key hub genes specifying matrix-associated signaling factors; SPOCK1, HTRA3 and ADGRD1. Several novel regulators of the WNT and TFG-β signaling pathway were identified in Müllerian ducts, including APCDD1 and DKK1, BMP3 and TGFBI. A number of novel transcription factors were also identified, including OSR1, FOXE1, PRICKLE1, TSHZ3 and SMARCA2. In addition, over 100 long non-coding RNAs (lncRNAs) were expressed during duct formation.

Conclusions

This study provides a rich resource of new candidate genes for Müllerian duct development and its disorders. It also sheds light on the molecular pathways engaged during tubulogenesis, a fundamental process in embryonic development.

Periostin and matrix stiffness combine to regulate myofibroblast differentiation and fibronectin synthesis during palatal healing

Although the matricellular protein periostin is prominently upregulated in skin and gingival healing, it plays contrasting roles in myofibroblast differentiation and matrix synthesis respectively. Palatal healing is associated with scarring that can alter or restrict maxilla growth, but the expression pattern and contribution of periostin in palatal healing is unknown. Using periostin-knockout (Postn^-/-) and wild-type (WT) mice, the contribution of periostin to palatal healing was investigated through 1.5 mm full-thickness excisional wounds in the hard palate. In WT mice, periostin was upregulated 6 days post-wounding, with mRNA levels peaking at day 12. Genetic deletion of periostin significantly reduced wound closure rates compared to WT mice. Absence of periostin reduced mRNA levels of pivotal genes in wound repair, including α-SMA/acta2, fibronectin and βigh3. Recruitment of fibroblasts and inflammatory cells, as visualized by immunofluorescent staining for fibroblast specific factor-1, vimentin, and macrophages markers Arginase-1 and iNOS was also impaired in Postn^-/-, but not WT mice. Palatal fibroblasts isolated from the hard palate of mice were cultured on collagen gels and prefabricated silicon substrates with varying stiffness. Postn^-/- fibroblasts showed a significantly reduced ability to contract a collagen gel, which was rescued by the exogenous addition of recombinant periostin. As the stiffness increased, Postn^-/- fibroblasts increasingly differentiated into myofibroblasts, but not to the same degree as the WT. Pharmacological inhibition of Rac rescued the deficient myofibroblastic phenotype of Postn^-/- cells. Low stiffness substrates (0.2 kPa) resulted in upregulation of fibronectin in WT cells, an effect which was significantly reduced in Postn^-/- cells. Quantification of immunostaining for vinculin and integrinβ1 adhesions revealed that Periostin is required for the formation of focal and fibrillar adhesions in mPFBs. Our results suggest that periostin modulates myofibroblast differentiation and contraction via integrinβ1/RhoA pathway, and fibronectin synthesis in an ECM stiffness dependent manner in palatal healing.

Integrated omics profiling reveals novel patterns of epigenetic programming in cancer-associated myofibroblasts

There is increasing evidence that stromal myofibroblasts play a key role in the tumour development however, the mechanisms by which they become reprogrammed to assist in cancer progression remain unclear. As cultured cancer-associated myofibroblasts (CAMs) retain an ability to enhance the proliferation and migration of cancer cells in vitro, it is possible that epigenetic reprogramming of CAMs within the tumour microenvironment may confer long-term pro-tumourigenic changes in gene expression. This study reports the first comparative multi-omics analysis of cancer-related changes in gene expression and DNA methylation in primary myofibroblasts derived from gastric and oesophageal tumours. In addition, we identify novel CAM-specific DNA methylation signatures, which are not observed in patient-matched adjacent tissue-derived myofibroblasts, or corresponding normal tissue-derived myofibroblasts. Analysis of correlated changes in DNA methylation and gene expression shows that different patterns of gene-specific DNA methylation have the potential to confer pro-tumourigenic changes in metabolism, cell signalling and differential responses to hypoxia. These molecular signatures provide new insights into potential mechanisms of stromal reprogramming in gastric and oesophageal cancer, while also providing a new resource to facilitate biomarker identification and future hypothesis-driven studies into mechanisms of stromal reprogramming and tumour progression in solid tumours.

TGFBI Protein Is Increased in the Urine of Patients with High-Grade Urothelial Carcinomas, and Promotes Cell Proliferation and Migration

Here, we discovered TGFBI as a new urinary biomarker for muscle invasive and high-grade urothelial carcinoma (UC). After biomarker identification using antibody arrays, results were verified in urine samples from a study population consisting of 303 patients with UC, and 128 urological and 58 population controls. The analyses of possible modifying factors (age, sex, smoking status, urinary leukocytes and erythrocytes, and history of UC) were calculated by multiple logistic regression. Additionally, we performed knockdown experiments with TGFBI siRNA in bladder cancer cells and investigated the effects on proliferation and migration by wound closure assays and BrdU cell cycle analysis. TGFBI concentrations in urine are generally increased in patients with UC when compared to urological and population controls (1321.0 versus 701.3 and 475.6 pg/mg creatinine, respectively). However, significantly increased TGFBI was predominantly found in muscle invasive (14,411.7 pg/mg creatinine), high-grade (8190.7 pg/mg) and de novo UC (1856.7 pg/mg; all p < 0.0001). Knockdown experiments in vitro led to a significant decline of cell proliferation and migration. In summary, our results suggest a critical role of TGFBI in UC tumorigenesis and particularly in high-risk UC patients with poor prognosis and an elevated risk of progression on the molecular level.

Integrative Omic Profiling Reveals Unique Hypoxia Induced Signatures in Gastric Cancer Associated Myofibroblasts

Although hypoxia is known to contribute to several aspects of tumour progression, relatively little is known about the effects of hypoxia on cancer-associated myofibroblasts (CAMs), or the consequences that conditional changes in CAM function may have on tumour development and metastasis. To investigate this issue in the context of gastric cancer, a comparative multiomic analysis was performed on populations of patient-derived myofibroblasts, cultured under normoxic or hypoxic conditions. Data from this study reveal a novel set of CAM-specific hypoxia-induced changes in gene expression and secreted proteins. Significantly, these signatures are not observed in either patient matched adjacent tissue myofibroblasts (ATMs) or non-cancer associated normal tissue myofibroblasts (NTMs). Functional characterisation of different myofibroblast populations shows that hypoxia-induced changes in gene expression not only enhance the ability of CAMs to induce cancer cell migration, but also confer pro-tumorigenic (CAM-like) properties in NTMs. This study provides the first global mechanistic insight into the molecular changes that contribute to hypoxia-induced pro-tumorigenic changes in gastric stromal myofibroblasts.

Chemerin acts via CMKLR1 and GPR1 to stimulate migration and invasion of gastric cancer cells: putative role of decreased TIMP-1 and TIMP-2

The chemokine-like peptide, chemerin, stimulates chemotaxis in several cell types. In this study we examined the expression of putative chemerin receptors in gastric cancer and the action of chemerin on cancer cell migration and invasion. Immunohistochemical studies of gastric tumors identified expression of two putative receptors, chemokine-like receptor-1 (CMKLR1) and G-protein coupled receptor 1(GPR1), in cancer cells; there was also some expression in stromal myofibroblasts although generally at a lower intensity. The expression of both receptors was detected in a gastric cancer cell line, AGS; chemerin itself was expressed in cultured gastric cancer myofibroblasts but not AGS cells. Chemerin stimulated (a) morphological transformation of AGS cells characterized by extension of processes and cell scattering, (b) migration in scratch wound assays and (c) both migration and invasion in Boyden chamber chemotaxis assays. These responses were inhibited by two putative receptor antagonists CCX832 and α-NETA. Inhibition of receptor expression by siRNA selectively reduced CMKLR1 or GPR1 and inhibited the action of chemerin indicating that both receptors contributed to the functional response. Using a proteomic approach employing stable isotope dynamic labeling of secretomes (SIDLS) to selectively label secreted proteins, we identified down regulation of tissue inhibitors of metalloproteinease (TIMP)1 and TIMP2 in media in response to chemerin. When cells were treated with chemerin and TIMP1 or TIMP2 the migration response to chemerin was reduced. The data suggest a role for chemerin in promoting the invasion of gastric cancer cells via CMKLR1 and GPR1at least partly by reducing TIMP1 and TIMP2 expression. Chemerin receptor antagonists have potential in inhibiting gastric cancer progression.

Activated gastric cancer-associated fibroblasts contribute to the malignant phenotype and 5-FU resistance via paracrine action in gastric cancer

Background

Cancer-associated fibroblasts (CAFs) play important roles in tumor progression. However, the behaviors of activated CAFs in gastric cancer remain to be determined. The aim of the present study was to investigate the correlations between activated gastric CAFs and the prognosis of patients with gastric cancer, and to determine the effects of activated CAFs on the malignant phenotype and 5-fluorouracil resistance in this cancer.

Methods

Ninety-five patients with primary gastric cancer were enrolled in this study. Activation states of gastric CAFs were evaluated by immunohistochemistry. A modified method for the primary culture of gastric CAFs was employed. Types of CAFs and activation states were identified by immunocytochemical and immunofluorescent staining. Cell co-culture and gastric CAF conditioned medium transfer models were established to investigate the paracrine effects of activated CAFs on the migration and invasion of gastric cell lines. The half maximal inhibitory concentration of 5-fluorouracil and levels of cell apoptosis were examined using cell viability assay and flow cytometry, respectively. Protein expression levels of associated molecules were measured by Western blotting.

Results

Kaplan–Meier survival curves showed that activated gastric CAFs identified via fibroblast activation protein were significantly related to poorer cumulative survival in gastric cancer patients. Five strains of CAFs were successfully cultured via the modified culture method, and three gastric CAFs strains were identified as activated gastric CAFs. The migration and invasion abilities of gastric cells were significantly enhanced in both the co-culture group and the conditioned medium group. The half maximal inhibitory concentration for 5-fluorouracil in BGC-823 cells was elevated after treatment with conditioned medium, and early apoptosis was inhibited. Additionally, an obvious elevation of epithelial–mesenchymal transition level was observed in the conditioned medium group.

Conclusions

Activated gastric CAFs correlate with a poor prognosis of cancer patients and may contribute to the malignant phenotype and the development of resistance to 5-fluorouracil via paracrine action in gastric cancer. Gastric CAFs with a specific activation state might be used as a tumor biomarker within the microenvironment for prognosis and as a new therapeutic target for chemoresistant gastric cancer.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0599-7) contains supplementary material, which is available to authorized users.

Stable Isotope Dynamic Labeling of Secretomes (SIDLS) Identifies Authentic Secretory Proteins Released by Cancer and Stromal Cells

Analysis of secretomes critically underpins the capacity to understand the mechanisms determining interactions between cells and between cells and their environment. In the context of cancer cell micro-environments, the relevant interactions are recognized to be an important determinant of tumor progression. Global proteomic analyses of secretomes are often performed at a single time point and frequently identify both classical secreted proteins (possessing an N-terminal signal sequence), as well as many intracellular proteins, the release of which is of uncertain biological significance. Here, we describe a mass spectrometry-based method for stable isotope dynamic labeling of secretomes (SIDLS) that, by dynamic SILAC, discriminates the secretion kinetics of classical secretory proteins and intracellular proteins released from cancer and stromal cells in culture. SIDLS is a robust classifier of the different cellular origins of proteins within the secretome and should be broadly applicable to nonproliferating cells and cells grown in short term culture.

Matrix metalloproteinase (MMP)-7 in Barrett's esophagus and esophageal adenocarcinoma: expression, metabolism, and functional significance

Matrix metalloproteinase (MMP)-7, unlike many MMPs, is typically expressed in epithelial cells. It has been linked to epithelial responses to infection, injury, and tissue remodeling including the progression of a number of cancers. We have now examined how MMP-7 expression changes in the progression to esophageal adenocarcinoma (EAC), and have studied mechanisms regulating its expression and its functional significance. Immunohistochemistry revealed that MMP-7 was weakly expressed in normal squamous epithelium adjacent to EAC but was abundant in epithelial cells in both preneoplastic lesions of Barrett's esophagus and EAC particularly at the invasive front. In the stroma, putative myofibroblasts expressing MMP-7 were abundant at the invasive front but were scarce or absent in adjacent tissue. Western blot and ELISA revealed high constitutive secretion of proMMP-7 in an EAC cell line (OE33) that was inhibited by the phosphatidylinositol (PI) 3-kinase inhibitor LY294002 but not by inhibitors of protein kinase C, or MAP kinase activation. There was detectable proMMP-7 in cultured esophageal myofibroblasts but it was undetectable in media. Possible metabolism of MMP-7 by myofibroblasts studied by proteomic analysis indicated degradation via extensive endopeptidase, followed by amino- and carboxpeptidase, cleavages. Myofibroblasts exhibited increased migration and invasion in response to conditioned media from OE33 cells that was reduced by MMP-7 knockdown and immunoneutralization. Thus, MMP-7 expression increases at the invasive front in EAC which may be partly attributable to activation of PI 3-kinase. Secreted MMP-7 may modify the tumor microenvironment by stimulating stromal cell migration and invasion.

Cancer Associated Fibroblasts: The Architects of Stroma Remodeling

Fibroblasts have exceptional phenotypic plasticity and capability to secrete vast amount of soluble factors, extracellular matrix components and extracellular vesicles. While in physiological conditions this makes fibroblasts master regulators of tissue homeostasis and healing of injured tissues, in solid tumors cancer associated fibroblasts (CAFs) co-evolve with the disease, and alter the biochemical and physical structure of the tumor microenvironment, as well as the behavior of the surrounding stromal and cancer cells. Thus CAFs are fundamental regulators of tumor progression and influence response to therapeutic treatments. Increasing efforts are devoted to better understand the biology of CAFs to bring insights to develop complementary strategies to target this cell type in cancer. Here we highlight components of the tumor microenvironment that play key roles in cancer progression and invasion, and provide an extensive overview of past and emerging understanding of CAF biology as well as the contribution that MS-based proteomics has made to this field.

Cell cycle dependent expression of the CCK2 receptor by gastrointestinal myofibroblasts: putative role in determining cell migration

The well‐known action of the gastric hormone gastrin in stimulating gastric acid secretion is mediated by activation of cholecystokinin‐2 receptors (CCK2R). The latter are expressed by a variety of cell types suggesting that gastrin is implicated in multiple functions. During wound healing in the stomach CCK2R may be expressed by myofibroblasts. We have now characterized CCK2R expression in cultured myofibroblasts. Immunocytochemistry showed that a relatively small proportion (1–6%) of myofibroblasts expressed the receptor regardless of the region of the gut from which they were derived, or whether from cancer or control tissue. Activation of CCK2R by human heptadecapeptide gastrin (hG17) increased intracellular calcium concentrations in a small subset of myofibroblasts indicating the presence of a functional receptor. Unexpectedly, we found over 80% of cells expressing CCK2R were also labeled with 5‐ethynyl‐2′‐deoxyuridine (EdU) which is incorporated into DNA during S‐phase of the cell cycle. hG17 did not stimulate EdU incorporation but increased migration of both EdU‐labeled and unlabelled myofibroblasts; the migratory response was inhibited by a CCK2R antagonist and by an inhibitor of IGF receptor tyrosine kinase; hG17 also increased IGF‐2 transcript abundance. The data suggest myofibroblasts express CCK2R in a restricted period of the cell cycle during S‐phase, and that gastrin accelerates migration of these cells; it also stimulates migration of adjacent cells probably through paracrine release of IGF. Together with previous findings, the results raise the prospect that gastrin controls the position of dividing myofibroblasts which may be relevant in wound healing and cancer progression in the gastrointestinal tract.

TGFBI functions similar to periostin but is uniquely dispensable during cardiac injury

Extracellular matrix production and accumulation stabilize the heart under normal conditions as well as form a protective scar after myocardial infarction injury, although excessive extracellular matrix accumulation with long-standing heart disease is pathological. In the current study we investigate the role of the matricellular protein, transforming growth factor beta-induced (TGFBI), which is induced in various forms of heart disease. Additionally, we sought to understand whether TGFBI is functionally redundant to its closely related family member periostin, which is also induced in the diseased heart. Surgical models of myocardial infarction and cardiac pressure overload were used in mice with genetic loss of Postn and/or Tgfbi to examine the roles of these genes during the fibrotic response. Additionally, cardiac-specific TGFBI transgenic mice were generated and analyzed. We observed that deletion of Tgfbi did not alter cardiac disease after myocardial infarction in contrast to greater ventricular wall rupture in Postn gene-deleted mice. Moreover, Tgfbi and Postn double gene-deleted mice showed a similar post-myocardial infarction disease phenotype as Postn-deleted mice. Over-expression of TGFBI in the hearts of mice had a similar effect as previously shown in mice with periostin over-expression. Thus, TGFBI and periostin act similarly in the heart in affecting fibrosis and disease responsiveness, although TGFBI is not seemingly necessary in the heart after myocardial infarction injury and is fully compensated by the more prominently expressed effector periostin.

Glucagon-like petide-2 acts on colon cancer myofibroblasts to stimulate proliferation, migration and invasion of both myofibroblasts and cancer cells via the IGF pathway

Glucagon-like peptide (GLP)-2 stimulates intestinal epithelial proliferation by acting, in part, via IGF release from sub-epithelial myofibroblasts. The response of myofibroblasts to GLP-2 remains incompletely understood. We studied the action of GLP-2 on myofibroblasts from colon cancer and adjacent tissue, and the effects of conditioned medium from these cells on epithelial cell proliferation, migration and invasion. GLP-2 stimulated proliferation, migration and invasion of myofibroblasts and the proliferative and invasive responses of cancer-associated myofibroblasts were greater than those of myofibroblasts from adjacent tissue. The responses were inhibited by an IGF receptor inhibitor, AG1024. Conditioned medium from GLP-2 treated myofibroblasts increased proliferation, migration and invasion of SW480, HT29, LoVo epithelial cells and these responses were inhibited by AG1024; GLP-2 alone had no effect on these cells. In addition, when myofibroblasts and epithelial cells were co-cultured in Ibidi chambers there was mutual stimulation of migration in response to GLP-2. The latter increased both IGF-1 and IGF-2 transcript abundance in myofibroblasts. Moreover, a number of IGF binding proteins (IGFBP-4, -5, -7) were identified in myofibroblast medium; in the presence of GLP-2 there was increased abundance of the cleavage products of IGBBP-4 and IGFBP-5 suggesting activation of a degradation mechanism that might increase IGF bioavailability. The data suggest that GLP-2 stimulates cancer myofibroblast proliferation, migration and invasion; GLP-2 acts indirectly on epithelial cells partly via increased IGF expression in myofibroblasts and partly, perhaps, by increased bioavailability through degradation of IGFBPs.

Dies1/VISTA expression loss is a recurrent event in gastric cancer due to epigenetic regulation

Dies1/VISTA induces embryonic stem-cell differentiation, via BMP-pathway, but also acts as inflammation regulator and immune-response modulator. Dies1 inhibition in a melanoma-mouse model led to increased tumour-infiltrating T-cells and decreased tumour growth, emphasizing Dies1 relevance in tumour-microenvironment. Dies1 is involved in cell de/differentiation, inflammation and cancer processes, which mimic those associated with Epithelial-to-Mesenchymal-Transition (EMT). Despite this axis linking Dies1 with EMT and cancer, its expression, modulation and relevance in these contexts is unknown. To address this, we analysed Dies1 expression, its regulation by promoter-methylation and miR-125a-5p overexpression, and its association with BMP-pathway downstream-effectors, in a TGFβ1-induced EMT-model, cancer cell-lines and primary samples. We detected promoter-methylation as a mechanism controlling Dies1 expression in our EMT-model and in several cancer cell-lines. We showed that the relationship between Dies1 expression and BMP-pathway effectors observed in the EMT-model, was not present in all cell-lines, suggesting that Dies1 has other cell-specific effectors, beyond the BMP-pathway. We further demonstrated that: Dies1 expression loss is a recurrent event in GC, caused by promoter methylation and/or miR-125a-5p overexpression and; GC-microenvironment myofibroblasts overexpress Dies1. Our findings highlight Dies1 as a novel player in GC, with distinct roles within tumour cells and in the tumour-microenvironment.

Distinct miRNA profiles in normal and gastric cancer myofibroblasts and significance in Wnt signaling

Stromal cells influence epithelial function in both health and disease. Myofibroblasts are abundant stromal cells that influence the cellular microenvironment by release of extracellular matrix (ECM) proteins, growth factors, proteases, cytokines, and chemokines. Cancer-associated myofibroblasts (CAMs) differ from adjacent tissue (ATMs) and normal tissue myofibroblasts (NTMs), but the basis of this is incompletely understood. We report now the differential expression of miRNAs in gastric cancer CAMs. MicroRNA arrays identified differences in the miRNA profile in gastric and esophageal NTMs and in CAMs from stomach compared with NTMs. miR-181d was upregulated in gastric CAMs. Analysis of differentially regulated miRNAs indicated an involvement in Wnt signaling. Examination of a microarray data set then identified Wnt5a as the only consistently upregulated Wnt ligand in gastric CAMs. Wnt5a stimulated miR-181d expression, and knockdown of miR-181d inhibited Wnt5a stimulation of CAM proliferation and migration. Analysis of miR-181d targets suggested a role in chemotaxis. Conditioned medium from CAMs stimulated gastric cancer cell (AGS) migration more than that from ATMs, and miR-181d knockdown reduced the effect of CAM-CM on AGS cell migration but had no effect on AGS cell responses to ATM conditioned media. The data suggest that dysregulation of miRNA expression in gastric CAMs, secondary to Wnt5a signaling, accounts at least in part for the effect of CAMs in promoting cancer cell migration.

The role of chemerin and ChemR23 in stimulating the invasion of squamous oesophageal cancer cells

BACKGROUND

Stromal cells, including cancer-associated myofibroblasts (CAMs), are recognised to be determinants of cancer progression, but the mechanisms remain uncertain. The chemokine-like protein, chemerin, is upregulated in oesophageal squamous cancer (OSC) CAMs compared with adjacent tissue myofibroblasts (ATMs). In this study, we hypothesised that chemerin stimulates OSC cell invasion.

METHODS

Expression of the chemerin receptor, ChemR23, in OSC was examined by immunohistochemistry. The invasion of OSC cells was studied using Boyden chambers and organotypic assays, and the role of chemerin was explored using siRNA, immunoneutralisation and a ChemR23 receptor antagonist. Matrix metalloproteinases (MMPs) were detected by western blot, enzyme assays or immunohistochemistry.

RESULTS

Immunohistochemistry indicated expression of the putative chemerin receptor ChemR23 in OSC. It was also expressed in the OSC cell line, OE21. Chemerin stimulated OE21 cell migration and invasion in Boyden chambers. Conditioned medium (CM) from OSC CAMs also stimulated OE21 cell invasion and this was inhibited by chemerin immunoneutralisation, the ChemR23 antagonist CCX832, and by pretreatment of CAMs with chemerin siRNA. In organotypic cultures of OE21 cells on Matrigel seeded with either CAMs or ATMs, there was increased OE21 cell invasion by CAMs that was again inhibited by CCX832. Chemerin increased MMP-1, MMP-2 and MMP-3 abundance, and activity in OE21 cell media, and this was decreased by inhibiting protein kinase C and p44/42 MAPK kinase but not PI-3 kinase.

CONCLUSIONS

The data indicate that OSC myofibroblasts release chemerin that stimulates OSC cell invasion. Treatments directed at inhibiting chemerin-ChemR23 interactions might be therapeutically useful in delaying progression in OSC.

Cancer-associated fibroblasts promote angiogenesis in gastric cancer through galectin-1 expression

BACKGROUND

Galectin-1, an evolutionarily conserved glycan-binding protein with angiogenic potential, was recently identified as being overexpressed in cancer-associated fibroblasts (CAFs) of gastric cancer. The role of endogenous CAF-derived galectin-1 on angiogenesis in gastric cancer and the mechanism involved remain unknown.

METHODS

Immunohistochemical staining was used to investigate the correlation between galectin-1 and vascular endothelial growth factor (VEGF) and CD31 expression in gastric cancer tissues and normal gastric tissues. Galectin-1 was knocked down in CAFs isolated from gastric cancer using small interfering ribonucleic acid (RNA), or overexpressed using recombinant lentiviruses, and the CAFs were co-cultured with human umbilical vein endothelial cells (HUVECs) or cancer cells. Subsequently, proliferation, migration, tube formation, and VEGF/VEGF receptor (VEGFR) 2 expression were detected. The role of CAF-derived galectin-1 in tumor angiogenesis in vivo was studied using the chick chorioallantoic membrane (CAM) assay.

RESULTS

Galectin-1 was highly expressed in the CAFs and was positively associated with VEGF and CD31 expression. In the co-culture, high expression of galectin-1 in the CAFs increased HUVEC proliferation, migration, tube formation, and VEGFR2 phosphorylation and enhanced VEGF expression in gastric cancer cells. The CAM assay indicated that high expression of galectin-1 in the CAFs accelerated tumor growth and promoted angiogenesis. In contrast, galectin-1 knockdown in the CAFs significantly inhibited this effect.

CONCLUSION

CAF-derived galectin-1 significantly promotes angiogenesis in gastric cancer and may be a target for angiostatic therapy.

Caveolin-1 is a modulator of fibroblast activation and a potential biomarker for gastric cancer

Stromal fibroblasts play an important role in chronic cancer-related inflammation and the development as well as progression of malignant diseases. However, the difference and relationship between inflammation-associated fibroblasts (IAFs) and cancer-associated fibroblasts (CAFs) are poorly understood. In this study, gastric cancer-associated fibroblasts (GCAFs) and their corresponding inflammation-associated fibroblasts (GIAFs) were isolated from gastric cancer (GC) with chronic gastritis and cultured in vitro. These activated fibroblasts exhibited distinct secretion and tumor-promoting behaviors in vitro. Using proteomics and bioinformatics techniques, caveolin-1 (Cav-1) was identified as a major network-centric protein of a sub-network consisting of 121 differentially expressed proteins between GIAFs and GCAFs. Furthermore, immunohistochemistry in a GC cohort showed significant difference in Cav-1 expression score between GIAFs and GCAFs and among patients with different grades of chronic gastritis. Moreover, silencing of Cav-1 in GIAFs and GCAFs using small interfering RNA increased the production of pro-inflammatory and tumor-enhancing cytokines and chemokines in conditioned mediums that elevated cell proliferation and migration when added to GC cell lines AGS and MKN45 in vitro. In addition, Cav-1 status in GIAFs and GCAFs independently predicted the prognosis of GC. Our findings indicate that Cav-1 loss contributes to the distinct activation statuses of fibroblasts in GC microenvironment and gastritis mucosa, and Cav-1 expression in both GCAFs and GIAFs may serve as a potential biomarker for GC progression.

Increased expression of chemerin in squamous esophageal cancer myofibroblasts and role in recruitment of mesenchymal stromal cells

Stromal cells such as myofibroblasts influence tumor progression. The mechanisms are unclear but may involve effects on both tumor cells and recruitment of bone marrow-derived mesenchymal stromal cells (MSCs) which then colonize tumors. Using iTRAQ and LC-MS/MS we identified the adipokine, chemerin, as overexpressed in esophageal squamous cancer associated myofibroblasts (CAMs) compared with adjacent tissue myofibroblasts (ATMs). The chemerin receptor, ChemR23, is expressed by MSCs. Conditioned media (CM) from CAMs significantly increased MSC cell migration compared to ATM-CM; the action of CAM-CM was significantly reduced by chemerin-neutralising antibody, pretreatment of CAMs with chemerin siRNA, pretreatment of MSCs with ChemR23 siRNA, and by a ChemR23 receptor antagonist, CCX832. Stimulation of MSCs by chemerin increased phosphorylation of p42/44, p38 and JNK-II kinases and inhibitors of these kinases and PKC reversed chemerin-stimulated MSC migration. Chemerin stimulation of MSCs also induced expression and secretion of macrophage inhibitory factor (MIF) that tended to restrict migratory responses to low concentrations of chemerin but not higher concentrations. In a xenograft model consisting of OE21 esophageal cancer cells and CAMs, homing of MSCs administered i.v. was inhibited by CCX832. Thus, chemerin secreted from esophageal cancer myofibroblasts is a potential chemoattractant for MSCs and its inhibition may delay tumor progression.

The neuroendocrine phenotype of gastric myofibroblasts and its loss with cancer progression

Stromal cells influence cancer progression. Myofibroblasts are an important stromal cell type, which influence the tumour microenvironment by release of extracellular matrix (ECM) proteins, proteases, cytokines and chemokines. The mechanisms of secretion are poorly understood. Here, we describe the secretion of marker proteins in gastric cancer and control myofibroblasts in response to insulin-like growth factor (IGF) stimulation and, using functional genomic approaches, we identify proteins influencing the secretory response. IGF rapidly increased myofibroblast secretion of an ECM protein, TGFβig-h3. The secretory response was not blocked by inhibition of protein synthesis and was partially mediated by increased intracellular calcium (Ca(2+)). The capacity for evoked secretion was associated with the presence of dense-core secretory vesicles and was lost in cells from patients with advanced gastric cancer. In cells responding to IGF-II, the expression of neuroendocrine marker proteins, including secretogranin-II and proenkephalin, was identified by gene array and LC-MS/MS respectively, and verified experimentally. The expression of proenkephalin was decreased in cancers from patients with advanced disease. Inhibition of secretogranin-II expression decreased the secretory response to IGF, and its over-expression recovered the secretory response consistent with a role in secretory vesicle biogenesis. We conclude that normal and some gastric cancer myofibroblasts have a neuroendocrine-like phenotype characterized by Ca(2+)-dependent regulated secretion, dense-core secretory vesicles and expression of neuroendocrine marker proteins; loss of the phenotype is associated with advanced cancer. A failure to regulate myofibroblast protein secretion may contribute to cancer progression.

Cancer-associated fibroblasts as another polarized cell type of the tumor microenvironment

Tumor- or cancer-associated fibroblasts (CAFs) are one of the most abundant stromal cell types in different carcinomas and comprise a heterogeneous cell population. Classically, CAFs are assigned with pro-tumorigenic effects stimulating tumor growth and progression. More recent studies demonstrated also tumor-inhibitory effects of CAFs suggesting that tumor-residing fibroblasts exhibit a similar degree of plasticity as other stromal cell types. Reciprocal interactions with the tumor milieu and different sources of origin are emerging as two important factors underlying CAF heterogeneity. This review highlights recent advances in our understanding of CAF biology and proposes to expand the term of cellular “polarization,” previously introduced to describe different activation states of various immune cells, onto CAFs to reflect their phenotypic diversity.

Proteomic profiling of the tumor microenvironment: recent insights and the search for biomarkers

Although gain of oncogene functions and loss of tumor suppressor functions are driving forces in tumor development, the tumor microenvironment, comprising the extracellular matrix, surrounding stroma, signaling molecules and infiltrating immune and other cell populations, is now also recognized as crucial to tumor development and metastasis. Many interactions at the tumor cell-environment interface occur at the protein level. Proteomic approaches are contributing to the definition of the protein constituents of the microenvironment and their sources, modifications, interactions and turnover, as well as providing information on how these features relate to tumor development and progression. Recently, proteomic studies have revealed how cancer cells modulate the microenvironment through their secreted proteins and how they can alter their protein constituents to adapt to the microenvironment. Moreover, the release of proteins from the microenvironment into the circulatory system has relevance for the development of blood-based cancer diagnostics. Here, we review how proteomic approaches are being applied to studies of the tumor microenvironment to decipher tumor-stroma interactions and to elucidate the role of host cells in the tumor microenvironment.

Na+/Ca2+ exchangers regulate the migration and proliferation of human gastric myofibroblasts

Gastrointestinal myofibroblasts are contractile, electrically nonexcitable, transitional cells that play a role in extracellular matrix production, in ulcer healing, and in pathophysiological conditions they contribute to chronic inflammation and tumor development. Na+/Ca2+ exchangers (NCX) are known to have a crucial role in Ca2+ homeostasis of contractile cells, however, no information is available concerning the role of NCX in the proliferation and migration of gastrointestinal myofibroblasts. In this study, our aim was to investigate the role of NCX in the Ca2+ homeostasis, migration, and proliferation of human gastrointestinal myofibroblasts, focusing on human gastric myofibroblasts (HGMs). We used microfluorometric measurements to investigate the intracellular Ca2+ and Na+ concentrations, PCR analysis and immunostaining to show the presence of the NCX, patch clamp for measuring NCX activity, and proliferation and migration assays to investigate the functional role of the exchanger. We showed that 53.0±8.1% of the HGMs present Ca2+ oscillations, which depend on extracellular Ca2+ and Na+, and can be inhibited by NCX inhibitors. NCX1, NCX2, and NCX3 were expressed at both mRNA and protein levels in HGMs, and they contribute to the intracellular Ca2+ and Na+ homeostasis as well, regardless of the oscillatory activity. NCX inhibitors significantly blocked the basal and insulin-like growth factor II-stimulated migration and proliferation rates of HGMs. In conclusion, we showed that NCX plays a pivotal role in regulating the Ca2+ homeostasis, migration, and proliferation of HGMs. The inhibition of NCX activity may be a potential therapeutic target in hyperproliferative gastric diseases.

Mapping proteolytic processing in the secretome of gastric cancer-associated myofibroblasts reveals activation of MMP-1, MMP-2, and MMP-3

Cancer progression involves changes in extracellular proteolysis, but the contribution of stromal cell secretomes to the cancer degradome remains uncertain. We have now defined the secretome of a specific stromal cell type, the myofibroblast, in gastric cancer and its modification by proteolysis. SILAC labeling and COFRADIC isolation of methionine containing peptides allowed us to quantify differences in gastric cancer-derived myofibroblasts compared with myofibroblasts from adjacent tissue, revealing increased abundance of several proteases in cancer myofibroblasts including matrix metalloproteinases (MMP)-1 and -3. Moreover, N-terminal COFRADIC analysis identified cancer-restricted proteolytic cleavages, including liberation of the active forms of MMP-1, -2, and -3 from their inactive precursors. In vivo imaging confirmed increased MMP activity when gastric cancer cells were xenografted in mice together with gastric cancer myofibroblasts. Western blot and enzyme activity assays confirmed increased MMP-1, -2, and -3 activity in cancer myofibroblasts, and cancer cell migration assays indicated stimulation by MMP-1, -2, and -3 in cancer-associated myofibroblast media. Thus, cancer-derived myofibroblasts differ from their normal counterparts by increased production and activation of MMP-1, -2, and -3, and this may contribute to the remodelling of the cancer cell microenvironment.

The role of plasminogen activator inhibitor-1 in gastric mucosal protection

Gastric mucosal health is maintained in response to potentially damaging luminal factors. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) disrupt protective mechanisms leading to bleeding and ulceration. The plasminogen activator system has been implicated in fibrinolysis following gastric ulceration, and an inhibitor of this system, plasminogen activator inhibitor (PAI)-1, is expressed in gastric epithelial cells. In Helicobacter pylori-negative patients with normal gastric histology taking aspirin or NSAIDs, we found elevated gastric PAI-1 mRNA abundance compared with controls; the increase in patients on aspirin was independent of whether they were also taking proton pump inhibitors. In the same patients, aspirin tended to lower urokinase plasminogen activator mRNA. Immunohistochemistry indicated PAI-1 localization to epithelial cells. In a model system using MKN45 or AGS-GR cells transfected with a PAI-1 promoter-luciferase reporter construct, we found no evidence for upregulation of PAI-1 expression by indomethacin, and, in fact, cyclooxygenase products such as PGE2 and PGI2 weakly stimulated expression. Increased gastric PAI-1 mRNA was also found in mice following gavage with ethanol or indomethacin, but plasma PAI-1 was unaffected. In PAI-1(-/-) mice, gastric hemorrhagic lesions in response to ethanol or indomethacin were increased compared with C57BL/6 mice. In contrast, in PAI-1-H/Kβ mice in which PAI-1 is overexpressed in parietal cells, there were decreased lesions in response to ethanol and indomethacin. Thus, PAI-1 expression is increased in gastric epithelial cells in response to mucosal irritants such as aspirin and NSAIDs probably via an indirect mechanism, and PAI-1 acts as a local autoregulator to minimize mucosal damage.