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

Profiling of Tumor Microenvironment Components Identifies Five Stroma-Related Genes with Prognostic Implications in Colorectal Cancer

Background: Tumor microenvironment (TME) significantly affects colorectal cancer (CRC) progression and therapeutic efficacy, particularly the infiltrating stromal components. This study profiled the TME composition of tumor tissue and identify TME-related, especially stroma-related genes having prognosis value in CRC patients. Materials and Methods: We used the ESTIMATE algorithm to assess stromal/immune component and divided 524 CRC cases of public dataset into high- and low-score groups. We analyzed the effect of the score on prognosis and extracted the differential expression genes (DEGs) between groups, which were stromal- and/or immune-related genes, and performed a prognostic investigation of the DEGs. Results: Higher stromal score correlated with poor survival, whereas the immune score was the inverse. By comparing global gene expression of cases with high vs. low stromal/immune scores, we extracted 474 stroma-related genes, 76 immune-related genes, and 498 intersection genes, which were explored by function enrichment and survival analysis. We identified the expression of five stroma-related genes (including ITGA7, PTPN14, SCG2, TNS1, and GRP) significantly associated with poorer survival, which were validated in the other two independent CRC cohorts. Conclusion: These results presented a comprehensive understanding of TME components and identified five stroma-related genes that predict poor outcomes in CRC patients.

Depression accelerates gastric cancer invasion and metastasis by inducing a neuroendocrine phenotype via the catecholamine/β2 -AR/MACC1 axis

Background

Depression is a common, easily ignored, accompanied disease of gastric cancer (GC) patients and is often observed with elevated plasma catecholamine levels. Depression frequently promotes GC progression and leads to poor clinical outcomes; however, the molecular mechanisms underlying depression‐induced GC progression remain poorly understood. We aimed to study the effects of depression on GC progression and explore possible mechanisms mediating the action of depression‐associated catecholamines on GC.

Methods

Depression states of GC patients were graded using the Patient Health Questionnaire‐9, and plasma catecholamine levels were examined by high performance liquid chromatography coupled with tandem mass spectrometry. Migrative and invasive GC cells were examined using transwell assays, and metastatic GC niches were imaged using bioluminescence technology in a depression mouse model established with chronic unpredictable mild stress. Mouse depression‐like behaviors were assessed through sucrose preference, forced swimming, and tail suspension tests. Characteristics of the neuroendocrine phenotype were observed via RT‐PCR, Western blotting, flow cytometry, and transmission electron microscopy.

Results

Fifty‐one GC patients (age: 53.61 ± 1.79 years; cancer duration: 3.71 ± 0.33 months; depression duration: 2.37 ± 0.38 months; male‐to‐female ratio: 1.55:1) were enrolled in the study. Depression grade was significantly higher in GC patients showing higher plasma levels of catecholamines (epinephrine: P = 0.018; noradrenaline: P = 0.009), higher oncogene metastasis‐associated in colon cancer‐1 (MACC1) level (P = 0.018), and metastasis (P < 0.001). Further, depression‐associated catecholamine specifically bound to the beta‐2 adrenergic receptor (β₂‐AR) and upregulated MACC1 expression, and thus promoting neuroendocrine phenotypic transformation through direct binding between MACC1 and synaptophysin. Eventually, the neuroendocrine phenotypic transformation accelerated GC invasion in vitro and metastasis in vivo. However, β₂‐AR antagonist ICI‐118,551 or MACC1 silencing effectively blocked the catecholamine‐induced neuroendocrine phenotypic transformation and eliminated depression‐enhanced GC migration and invasion. Moreover, β₂‐AR blocking or MACC1 silencing prevented GC metastasis attributed to a neuroendocrine phenotype in a depression mouse model.

Conclusions

Catecholamine‐induced neuroendocrine phenotypes of GC cells led to depression‐accelerated GC invasion and metastasis via the β₂‐AR/MACC1 axis, while β₂‐AR antagonist or MACC1 silencing could reverse it, showing promising potential therapeutic strategies for improving the outcome of GC patients with comorbid depression.

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.

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.

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.

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.

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.

Mesenchymal Stem Cells Exhibit Regulated Exocytosis in Response to Chemerin and IGF

Mesenchymal stem cells (MSCs) play important roles in tissue repair and cancer progression. Our recent work suggests that some mesenchymal cells, notably myofibroblasts exhibit regulated exocytosis resembling that seen in neuroendocrine cells. We now report that MSCs also exhibit regulated exocytosis. Both a G-protein coupled receptor agonist, chemerin, and a receptor tyrosine kinase stimulant, IGF-II, evoked rapid increases in secretion of a marker protein, TGFβig-h3. The calcium ionophore, ionomycin, also rapidly increased secretion of TGFβig-h3 while inhibitors of translation (cycloheximide) or secretory protein transport (brefeldin A) had no effect, indicating secretion from preformed secretory vesicles. Inhibitors of the chemerin and IGF receptors specifically reduced the secretory response. Confocal microscopy of MSCs loaded with Fluo-4 revealed chemerin and IGF-II triggered intracellular Ca²⁺ oscillations requiring extracellular calcium. Immunocytochemistry showed co-localisation of TGFβig-h3 and MMP-2 to secretory vesicles, and transmission electron-microscopy showed dense-core secretory vesicles in proximity to the Golgi apparatus. Proteomic studies on the MSC secretome identified 64 proteins including TGFβig-h3 and MMP-2 that exhibited increased secretion in response to IGF-II treatment for 30min and western blot of selected proteins confirmed these data. Gene ontology analysis of proteins exhibiting regulated secretion indicated functions primarily associated with cell adhesion and in bioassays chemerin increased adhesion of MSCs and adhesion, proliferation and migration of myofibroblasts. Thus, MSCs exhibit regulated exocytosis that is compatible with an early role in tissue remodelling.

Gastrointestinal Fibroblasts Have Specialized, Diverse Transcriptional Phenotypes: A Comprehensive Gene Expression Analysis of Human Fibroblasts

BACKGROUND

Fibroblasts are the principal stromal cells that exist in whole organs and play vital roles in many biological processes. Although the functional diversity of fibroblasts has been estimated, a comprehensive analysis of fibroblasts from the whole body has not been performed and their transcriptional diversity has not been sufficiently explored. The aim of this study was to elucidate the transcriptional diversity of human fibroblasts within the whole body.

METHODS

Global gene expression analysis was performed on 63 human primary fibroblasts from 13 organs. Of these, 32 fibroblasts from gastrointestinal organs (gastrointestinal fibroblasts: GIFs) were obtained from a pair of 2 anatomical sites: the submucosal layer (submucosal fibroblasts: SMFs) and the subperitoneal layer (subperitoneal fibroblasts: SPFs). Using hierarchical clustering analysis, we elucidated identifiable subgroups of fibroblasts and analyzed the transcriptional character of each subgroup.

RESULTS

In unsupervised clustering, 2 major clusters that separate GIFs and non-GIFs were observed. Organ- and anatomical site-dependent clusters within GIFs were also observed. The signature genes that discriminated GIFs from non-GIFs, SMFs from SPFs, and the fibroblasts of one organ from another organ consisted of genes associated with transcriptional regulation, signaling ligands, and extracellular matrix remodeling.

CONCLUSIONS

GIFs are characteristic fibroblasts with specific gene expressions from transcriptional regulation, signaling ligands, and extracellular matrix remodeling related genes. In addition, the anatomical site- and organ-dependent diversity of GIFs was also discovered. These features of GIFs contribute to their specific physiological function and homeostatic maintenance, and create a functional diversity of the gastrointestinal tract.