Gremlin 1 Expression Research Articles

Unravelling cardiomyopathies: a comprehensive analysis of phenotypic diversity, endomyocardial biopsy patterns, and the impact of Gremlin-1 on clinical prognosis

Abstract Background Cardiomyopathies are the main cause of progressive heart failure (HF) and despite outstanding advances of diagnostics and therapies, mortality remains high.1,2 The current phenotype-based classification of non-ischemic cardiomyopathies (NICM) is based on a clinical workflow including endomyocardial biopsy (EMB).3-5 Inflammation and fibrosis are essentially involved in progression of HF and lead to development of adverse cardiovascular (CV) events.6,7 The diagnostic algorithm facilitates risk stratification of HF patients but nonetheless risk factors often remain inapparent prior to disease incidence. Objective In this study we investigate EMB patters in patients with NICM and elucidate alterations associated with phenotypic diversity and progression of HF. Methods We prospectively enrolled patients with HF due to NICM in a large-scale all-comers cohort (n=703). All patients underwent guideline-based phenotypic classification including EMB, and RNA data were acquired alongside histological analyses within the myocardium. We then performed a ten-year follow-up to screen for disease progression. Results A guideline-based classification of patients with NICM resulted in a phenotyping of aetiological risk groups (Figure 1A). We found that characteristic expression of fibroinflammatory mediators within the myocardium occurred in patients with symptomatic NICM (Figure 1B). We found that elevated expression of Gremlin-1 (Grem), a potent downstream profibrotic mediator of TGFß pathway, was associated with pro-fibrotic cardiac remodelling (Figure 1C). Further, Gremlin-1 was associated with a significant decrease of left ventricular functional capacity and inversely correlated with late gadolinium enhancement (LGE) (Figure 1D&E). Moreover, the expression of Gremlin-1 was enriched with pro-fibrotic and inflammatory RNA signalling pathways hinting at underlying pathophysiological cascades (Figure 2A&B). Most strikingly, the expression of Gremlin-1 was independently associated with an increased CV risk during the ten-year follow-up (Figure 2C). Thus, patients with Gremlin-1+ EMB were at elevated risk to suffer from all-cause mortality and number of patients eligible for ICD implantation was critically enhanced in patients with Gremlin-1+ EMB (Figure 2D-F). In addition, the estimation of an elevated CV risk by machine learning including Gremlin-1 improved the ten-year risk stratification among all patients with NICM (Figure 2G). Thus, Gremlin-1 was associated with cardiac remodelling and disease activity in HF patients (Figure 2H). Conclusion Our results unveiled that Gremlin-1 is associated with inflammation and cardiac remodelling in patients with symptomatic cardiomyopathy and patients with Gremlin-1+ EMB are at elevated risk to develop adverse CV events. Thus, the histological evaluation of Gremlin-1 may help to identify pathophysiological cascades and improve early risk discrimination and management of HF patients.Figure 1Figure 2

GREM1 may be a biological indicator and potential target of bladder cancer

Gremlin 1 (GREM1) can regulate the development of many cancers. However, a few studies have revealed the role of GREM1 in bladder cancer (BC). To evaluate the expression and potential function of GREM1 in bladder cancer, we used R version 3.6.3 and related packages to analyze the data from common databases. Samples from our institution were assessed by immunohistochemical staining (IHC), which was approved by the Institutional Ethics Committee (K20220830). GREM1 was highly expressed in BC tissues according to the TCGA and IHC data. Data from TCGA, GSE31684, GSE32894, and IHC showed that GREM1 has significant prognostic value for BC patients. GREM1 is involved in immune and metabolism-related pathways. According to the TIDE algorithm, 61.0% of patients with low GREM1 expression responded well to immunotherapy, compared to only 13.3% in the high GREM1 expression group. High GREM1 expression was associated with sensitivity to cisplatin, docetaxel, gemcitabine, and vinblastine. Thus, GREM1 can predict prognosis and responses to immunotherapy and chemotherapy in BC patients, making it a potential biomarker and therapeutic target.

Quantification of Gremlin 1 throughout the tumor stroma using whole slide imaging and its clinicopathological significance in gastric cancer.

Gremlin 1 (GREM1) is an antagonist of bone morphogenetic protein (BMP). GREM1 is expressed in the stromal cells of various carcinomas and promotes tumor progression by suppressing BMP signaling. We designed this study to establish an evaluation strategy for GREM1 expression, focusing on the tumor stroma, and to examine its clinicopathological significance in gastric cancer (GC) progression. We employed RNA in situ hybridization (ISH) to evaluate the prognostic value of GREM1 expression in a cohort of 104 surgically resected GC cases and assessed ISH scores according to previous reports. GREM1 expression was observed in tumor stromal cells, including fibroblasts. We defined GREM1-positive cells as those expressing ISH score ≥ 3 and quantified the number of GREM1-positive cells using image analysis software. We examined the relationship between the number of GREM1-positive cells in the tumor stroma and clinicopathological features. The number of GREM1-positive cells per tumor stroma ranged from 0 to 714.7 cells/mm2 (median, 1.65 cells/mm2). We divided the 104 GC cases into GREM1-High and GREM1-Low expression groups based on the abovementioned median value. GREM1-High expression group was significantly associated with a more advanced pT grade, pN grade, lymphatic invasion, and venous invasion. Kaplan-Meier analysis showed significantly poorer survival in the GREM1-High expression group than in the GREM1-Low expression group. These results indicated that GREM1 expression in GC is localized in tumor stromal cells, and that high GREM1 expression in the tumor stroma could be a poor prognostic factor.

Blocking Gremlin1 inhibits M1 macrophage polarization through Notch1/Hes1 signaling pathway in apical periodontitis

Background Gremlin1 is a multifunctional protein whose expression is demonstrated to be involved in a series of physiology and pathological processes. The association between Gremlin1 and apcial periodontitis (AP) has been established. M1-polarized macrophages are crucial immune cells that exacerbate the progression of apical periodontal inflammatory response, but the function of Gremlin1 during macrophages activation in periapical lesions is still unclear. This study attempts to explore the regulatory effects of Gremlin1 on macrophage polarization on apical periodontitis microenviroment. Methods Clinical specimens were used to determine the expression of Gremlin1 in periapical tissues by immunohistochemical (IHC) staining. Then, the disease models of periapical inflammation in rats were established, and adenovirus- associated virus (AAVs) was used to blockade Gremlin1 expression. Lentivirus carrying sh-Gremlin1 particles were used to transfect THP-1 induced M1-subtype macrophages. To assess the expression of associated molecules, Western blot, immunofluorescence staining were performed. Results Gremlin1 was significantly up-regulated in the periapical tissues of subjects with AP as identified by IHC staining, and positively correlated with levels of M1 macrophage-associated genes. Rats AP model with inhibition of Gremlin1 in periapical lesions exhibited limited infiltration of macrophages and decreased expression of M1 macrophage-related genes in periapical lesions. Furthermore, Gremlin1 blockade substantially decreased the Notch1/Hes1 signaling pathway activation level. The in vitro experiments confirmed the above results. Conclusion Taken together, current study illustrated that the Gremlin1 suppression in periapical lesions inhibited M1 macrophage polarization through Notch1/Hes1 axis. Moreover, Gremlin1 may act as a potential candidate in the treatment of AP.

MiR-455/GREM1 axis promotes colorectal cancer progression and liver metastasis by affecting PI3K/AKT pathway and inducing M2 macrophage polarization

BackgroundColorectal cancer is among the most common malignant tumors affecting the gastrointestinal tract. Liver metastases, a complication present in approximately 50% of colorectal cancer patients, are a considerable concern. Recently, studies have revealed the crucial role of miR-455 in tumor pathogenesis. However, the effect of miR-455 on the progression of liver metastases in colorectal cancer remains controversial. As an antagonist of bone morphogenetic protein(BMP), Gremlin 1 (GREM1) may impact organogenesis, body patterning, and tissue differentiation. Nevertheless, the role of miR-455 in regulating GREM1 in colorectal cancer liver metastases and how miR-455/GREM1 axis influences tumour immune microenvironment is unclear.MethodsBioinformatics analysis shows that miR-455/GREM1 axis plays crucial role in liver metastasis of intestinal cancer and predicts its possible mechanism. To investigate the impact of miR-455/GREM1 axis on the proliferation, invasion, and migration of colorectal cancer cells, colony formation assay, wound healing and transwell assay were examined in vitro. The Dual-Luciferase reporter gene assay and RNA pull-down assay confirmed a possible regulatory effect between miR-455 and GREM1. In vivo, colorectal cancer liver metastasis(CRLM) model mice was established to inquiry the effect of miR-455/GREM1 axis on tumor growth and macrophage polarization. The marker of macrophage polarization was tested using immunofluorescence(IF) and quantitative real-time polymerase chain reaction(qRT-PCR). By enzyme-linked immunosorbent assay (ELISA), cytokines were detected in culture medium supernatants.ResultsWe found that miR-455 and BMP6 expression was increased and GREM1 expression was decreased in liver metastase compared with primary tumor. miR-455/GREM1 axis promotes colorectal cancer cells proliferation, migration, invasion via affected PI3K/AKT pathway. Moreover, downregulating GREM1 augmented BMP6 expression in MC38 cell lines, inducing M2 polarization of macrophages, and promoting liver metastasis growth in CRLM model mice.ConclusionThese data suggest that miR-455/GREM1 axis promotes colorectal cancer progression and liver metastasis by affecting PI3K/AKT pathway and inducing M2 macrophage polarization. These results offer valuable insights and direction for future research and treatment of CRLM.

Gastrodin Ameliorates the Inflammation, Oxidative Stress, and Extracellular Matrix Degradation of IL-1β-Mediated Fibroblast-Like Synoviocytes via Suppressing the Gremlin-1/NF-κB Pathway.

Synovial inflammation plays a crucial role in osteoarthritis (OA). Gastrodin (GAS), an active ingredient derived from the Gastrodia elata Blume rhizome, possesses antioxidant and anti-inflammatory pharmacological effects. This research aimed to evaluate the function and molecular mechanism of GAS on human fibroblast-like synoviocytes of osteoarthritis (HFLS-OA) induced by interleukin (IL)-1β. The impact of GAS on the viability of IL-1β-treated HFLS-OA cells was assessed using the cell counting kit-8 (CCK-8). Quantitative real-time reverse transcription PCR (qRT-PCR) was employed to detect changes in IL-8, IL-6, monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor (TNF)-α, and Gremlin-1 mRNA expression in each group. Corresponding kits were utilized to measure the catalase (CAT) and superoxide dismutase (SOD) activities, as well as the nitric oxide (NO) level. Western blot analysis was conducted to examine the expression of extracellular matrix degradation-associated proteins and nuclear factor kappa-B (NF-κB) pathway-correlated proteins in each group. GAS significantly promoted the proliferation of IL-1β-induced HFLS-OA cells and concurrently down-regulated Gremlin-1 mRNA expression (p < 0.05). Through the down-regulation of Gremlin-1 expression, GAS exhibited the following effects: decreased IL-8, IL-6, and TNF-α mRNA expression, as well as NO levels (p < 0.05); increased SOD and CAT activities (p < 0.05); down-regulated matrix metallopeptidase 13 (MMP-13) and MMP-1 protein expression levels (p < 0.01); and up-regulated collagen II protein expression level (p < 0.01) in IL-1β-treated HFLS-OA cells. Additionally, GAS decreased phospho-inhibitory kappa B (p-IκB)/IκB, phospho-inhibitory kappa B kinase (p-IKK)/IKK, and p-p65/p65 ratios in IL-1β-induced HFLS-OA cells by inhibiting Gremlin-1 expression (p < 0.01). GAS demonstrates a positive impact on inflammation, oxidative stress, and extracellular matrix degradation in IL-1β-mediated HFLS-OA cells. This effect is achieved by suppressing Gremlin-1 expression and reducing NF-κB pathway activity.

Increased Gremlin1 Expression in Pancreatic Ductal Adenocarcinoma Promotes a Fibrogenic Stromal Microenvironment.

The pancreatic ductal adenocarcinoma (PDAC) microenvironment is primarily composed of cancer-associated fibroblasts (CAFs) and immune cells. Gremlin1 (Grem1) is a profibrogenic factor that promotes tumorigenesis in several cancers. However, the role of Grem1 in the PDAC microenvironment is not adequately defined. We correlated Grem1 levels with activated stroma and immune cells in human PDAC using The Cancer Genome Atlas (TCGA) RNA-sequencing data and characterized the expression of Grem1 transcripts and isoforms in pancreatic cell lines and PDAC tissues. We assessed the role of Grem1 in the microenvironment by in vitro studies. Grem1 expression is associated with an activated stroma and increased M1 and M2 macrophages. Only full length Grem1 variant 1 and isoform 1 were detectable in human pancreatic cells, and remarkably high levels of Grem1 were observed in pancreatic fibroblasts (P < 0.05). Immunohistochemistry detected Grem1 protein in PDAC tumor cells and stromal cells, which correlated with infiltrating macrophages in PDAC tumors. Grem1 knockdown in CAFs suppressed transforming growth factor (TGF)-β-induced extracellular matrix proteins (P < 0.05). Grem1 recombinant protein treatment in vitro increased M1 and M2 macrophages (P < 0.05). Grem1 acts as a profibrogenic factor in the PDAC microenvironment via modulation of fibroblasts and macrophages. Grem1 may have the potential to be developed as a therapeutic target for PDAC.

Abstract 5977: A first-in-human, open-label, multi-center phase 1 study of TST003, a GREM 1 inhibitor, in subjects with locally advanced or metastatic solid tumors

Abstract Background: Gremlin-1 (GREM1), a member of the TGF-β superfamily, plays a key role in EMT, and cancer cell proliferation by binding to BMPs. GREM1 is widely expressed in various human cancers and TME stromal cells. Overexpression of GREM1 is correlated with poor prognosis. TST003 is a novel humanized IgG1 monoclonal antibody targeting GREM1 with high affinity and selectivity, and it blocks GREM1 binding to BMP2/4 resulting in enhanced BMP signaling. This study will investigate TST003’s safety, tolerability, and preliminary anti-tumor activity in patients with advanced solid tumors. Objectives: The primary objectives are to evaluate the safety and tolerability and determine the maximum tolerated dose and/or optimal biologic dose(s) of TST003. Secondary objectives include pharmacokinetic, pharmacodynamic and preliminary anti-tumor activity of TST003. A comprehensive biomarker plan will be implemented to analyze GREM1 expression, BMP signaling pathway, and tumor microenvironment with tumor tissues (including tumor cells, CAFs, Teff, Treg, MDSCs and TAMs), as well as circulating tumor DNA to explore the correlation among drug exposure, pharmacodynamic markers and clinical outcomes. Method: This is a first in human Phase 1 study in locally advanced or metastatic solid tumor subjects having tumor progression during or after prior therapies and have no standard therapy that could confer clinical benefit. It comprises of the Part 1 Dose Escalation and the Part 2 Pharmacodynamic Cohorts. Part 1 will evaluate sequential dose levels of 1, 3, 10, 20 and 30 mg/kg TST003 iv., every three weeks as a single agent. The traditional “3+3” design were used for dose escalation of the first two cohorts (1 and 3 mg/kg), and Bayesian Optimal Interval (BOIN) Design with prespecified cohort size of 3 is used in the following cohorts. Part 2 will include 2 pharmacodynamic cohorts to evaluate the pharmacokinetic (PK) profile, pharmacodynamic (PD) markers, preliminary tumor response, as well as safety of TST003 as monotherapy in locally advanced or metastatic colorectal adenocarcinoma (CRC) subjects. The 2 doses used in the pharmacodynamic cohorts will be chosen from Part 1 and are expected to be within the pharmacologically active range based on nonclinical PK/PD modeling and available clinical PK/PD data from the ongoing study. Baseline GREM1 expression will be analyzed by immunohistochemistry. In each pharmacodynamic cohort, around 13-18 subjects will be enrolled to ensure at least 7 GREM1 positive subjects. Eligible subjects will receive TST003 until unacceptable toxicity or disease progression by RECIST v1.1. The enrollment is ongoing in clinical centers in the US and China. No significant safety signals were reported in the first few patients treated with TST003. Clinical Trial Information: NCT05731271. Study Sponsor: Suzhou Transcenta Therapeutics Co., Ltd. Citation Format: Ismael Rodriguez Rivera, Lin Shen, Shivaani Kummar, Minal Barve, Caroline Germa, Chuan Qi, Lei Chen, Jenny Milata, Jenny Yao, Li Shen, Xuelian Zhu. A first-in-human, open-label, multi-center phase 1 study of TST003, a GREM 1 inhibitor, in subjects with locally advanced or metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5977.

Expression mapping of GREM1 and functional contribution of its secreting cells in the brain using transgenic mouse models

GREMLIN1 (GREM1) is a secreted protein that antagonizes bone morphogenetic proteins (BMPs). While abnormal GREM1 expression has been reported to cause behavioral defects in postpartum mice, the spatial and cellular distribution of GREM1 in the brain and the influence of the GREM1-secreting cells on brain function and behavior remain unclear. To address this, we designed a genetic cassette incorporating a 3×Flag-TeV-HA-T2A-tdTomato sequence, resulting in the creation of a novel Grem1Tag mouse model, expressing an epitope tag (3×Flag-TeV-HA-T2A) followed by a fluorescent reporter (tdTomato) under the control of the endogenous Grem1 promoter. This design facilitated precise tracking of the cell origin and distribution of GREM1 in the brain using tdTomato and Flag (or HA) markers, respectively. We confirmed that the Grem1Tag mouse exhibited normal motor, cognitive, and social behaviors at postnatal 60 days (P60), compared with C57BL/6J controls. Through immunofluorescence staining, we comprehensively mapped the distribution of GREM1-secreting cells across the central nervous system. Pervasive GREM1 expression was observed in the cerebral cortex (Cx), medulla, pons, and cerebellum, with the highest levels in the Cx region. Notably, within the Cx, GREM1 was predominantly secreted by excitatory neurons, particularly those expressing calcium/calmodulin-dependent protein kinase II alpha (Camk2a), while inhibitory neurons (parvalbumin-positive, PV+) and glial cells (oligodendrocytes, astrocytes, and microglia) showed little or no GREM1 expression. To delineate the functional significance of GREM1-secreting cells, a selective ablation at P42 using a diphtheria toxin A (DTA) system resulted in increased anxiety-like behavior and impaired memory in mice. Altogether, our study harnessing the Grem1Tag mouse model reveals the spatial and cellular localization of GREM1 in the mouse brain, shedding light on the involvement of GREM1-secreting cells in modulating brain function and behavior. Our Grem1Tag mouse serves as a valuable tool for further exploring the precise role of GREM1 in brain development and disease.

The possible role of Gremlin1 in inflammatory apical periodontitis

ObjectiveIn this study, we investigated the involvement of Gremlin1 on the pathological process of apical periodontitis and detect the underlying mechanisms preliminarily. MethodsClinical healthy and inflamed periapical specimens were collected. Then, apical periodontitis (AP) animal models were established by consistent pulp exposure. In addition, AAV-shGremlin1 was injected into inflamed periapical lesions to inhibit the expression of Gremlin1. Alveolar bone loss was measured by Micro-CT. Furthermore, immunohistochemical or immunofluorescence staining of Gremlin1, phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β were performed. ResultsThe expression of Gremlin1 is markedly increased in periapical lesions not only in clinic samples but also in animal models. Moreover, in rats’ AP model, we uncovered that the Gremlin1 protein expression levels in apical lesions is positively correlated with those of IL-1β. Besides, the blockade of Gremlin1 in periapical lesions could substantially suppress the alveolar bone loss and restrains the inflammatory status by impacting the activation levels of phosphorylated-CREB, ICAM-1, VCAM-1, IL-1β. ConclusionsTaken together, these results illustrated that Gremlin1 acts as a crucial mediator and possibly serves as a potential diagnostic marker for periapical periodontitis. Discovery of new factors involved in the pathophysiology of periapical periodontitis could contribute to the development of novel therapeutic treatment for the disease.

Current status and prospects of GREM1 research in cancer (Review).

GREM1 is a secreted protein that antagonizes bone morphogenetic proteins (BMPs) and participates in critical biological processes, including embryonic development, organogenesis and tissue differentiation. Gremlin 1 (GREM1) is also an inhibitor of TGF-β and a ligand for vascular endothelial growth factor receptor 2. In addition, GREM1 can induce cells, participate in the process of epithelial-mesenchymal transition, and then participate in tumor development. GREM1 has a variety of biological functions and can participate in the malignant progression of a variety of tumors through the BMP signaling pathway. GREM1 also can inhibit TGF-β in some tumors, thereby inhibiting tumors, and its involvement in tumor development varies in different types of cancer. The present review examines the role and function of GREM1 in tumors. GREM1 is expressed in a variety of tumor types. GREM1 expression can affect the epithelial-mesenchymal transformation of tumor cells. GREM1 has been studied in breast and colon cancer, and its potential role is to promote cancer. However, in pancreatic cancer, which was found to act differently from other cancer types, overexpression of GREM1 inhibits tumor metastasis. The present review suggests that GREM1 can be a diagnostic and prognostic indicator. In future studies, the study of GREM1 based on single-cell sequencing technology will further clarify its role and function in tumors.

Gremlin-1 promotes IL-1β-stimulated chondrocyte inflammation and extracellular matrix degradation via activation of the MAPK signaling pathway.

The role and mechanism of Gremlin-1 in osteoarthritis (OA) were expected to be probed in this study. Firstly, an in vitro OA model was constructed by stimulating human chondrocyte cell line CHON-001 with IL-1β. Next, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) were utilized for assessing the effect of IL-1β with different concentrations (5, 10, and 20 ng/mL) on the activity and Gremlin-1 messenger RNA of CHON-001 cells, respectively. Besides, the influence of knocking down/over-expressing Gremlin-1 on the inflammatory factors (IL-6, TNF-α, IL-18 and PGE2), oxidative stress-related substances (malondialdehyde [MDA]; superoxide dismutase [SOD]; lactate dehydrogenase [LDH]), extracellular matrix (ECM) degradation-related proteins, and mitogen-activated protein kinase (MAPK) pathway proteins in IL-1β-stimulated CHON-001 cells were tested by enzyme-linked immunosorbent assay, related kits, qRT-PCR, and western blot, respectively. IL-1β inhibited CHON-001 cell proliferation and upregulated Gremlin-1 expression in a concentration-dependent manner. Overexpression of Gremlin-1 increased the IL-6, TNF-α, IL-18, PGE2, and MDA levels, enhanced the LDH activity, and decreased the SOD activity in IL-1β-induced CHON-001 cells; while the effect of Gremlin-1 knockdown on the above factors was in contrast with that of the overexpression. Furthermore, overexpression of Gremlin-1 upregulated protein expression of matrix metalloproteinase (MMP)-3, MMP-13, and ADAMTS4 while downregulated protein expression of collagen III, aggrecan, and SOX-9 in IL-1β-stimulated CHON-001 cells. Besides, overexpression of Gremlin-1 increased the p-p38/p38 value while decreased the p-JNK/JNK value in L-1β-stimulated CHON-001 cells; however, knockdown of Gremlin-1 reversed the above results. Gremlin-1 may promote IL-1β-stimulated CHON-001 cell inflammation and ECM degradation by activating the MAPK signaling pathway.

Overexpression of GREM1 Improves the Survival Capacity of Aged Cardiac Mesenchymal Progenitor Cells via Upregulation of the ERK/NRF2-Associated Antioxidant Signal Pathway.

Ischemic heart disease is the leading cause of mortality in the United States. Progenitor cell therapy can restore myocardial structure and function. However, its efficacy is severely limited by cell aging and senescence. Gremlin-1 (GREM1), a member of the bone morphogenetic protein antagonist family, has been implicated in cell proliferation and survival. However, GREM1's role in cell aging and senescence has never been investigated in human cardiac mesenchymal progenitor cells (hMPCs). Therefore, this study assessed the hypothesis that overexpression of GREM1 rejuvenates the cardiac regenerative potential of aging hMPCs to a youthful stage and therefore allows better capacity for myocardial repair. We recently reported that a subpopulation of hMPCs with low mitochondrial membrane potential can be sorted from right atrial appendage-derived cells in patients with cardiomyopathy and exhibit cardiac reparative capacity in a mouse model of myocardial infarction. In this study, lentiviral particles were used to overexpress GREM1 in these hMPCs. Protein and mRNA expression were assessed through Western blot and RT-qPCR. FACS analysis for Annexin V/PI staining and lactate dehydrogenase assay were used to assess cell survival. It was observed that cell aging and cell senescence led to a decrease in GREM1 expression. In addition, overexpression of GREM1 led to a decrease in expression of senescence genes. Overexpression of GREM1 led to no significant change in cell proliferation. However, GREM1 appeared to have an anti-apoptotic effect, with an increase in survival and decrease in cytotoxicity evident in GREM1-overexpressing hMPCs. Overexpressing GREM1 also induced cytoprotective properties by decreasing reactive oxidative species and mitochondrial membrane potential. This result was associated with increased expression of antioxidant proteins, such as SOD1 and catalase, and activation of the ERK/NRF2 survival signal pathway. Inhibition of ERK led to a decrease in GREM1-mediated rejuvenation in terms of cell survival, which suggests that an ERK-dependent pathway may be involved. Taken altogether, these results indicate that overexpression of GREM1 can allow aging hMPCs to adopt a more robust phenotype with improved survival capacity, which is associated with an activated ERK/NRF2 antioxidant signal pathway.

Evaluation of GREM1 and THBS2 as prognostic markers in in non-small cell lung cancer.

To analyze the correlation between bone morphogenetic protein (BMP) antagonist Gremlin 1 (GREM1), Thrombospondin-2 (THBS2) and immune cell infiltration in non-small cell lung cancer (NSCLC) and the related clinical significance. A total of 150 NSCLC patients admitted to our hospital during May 2019-January 2022 were picked. The expression of GREM1 and THBS2 and the infiltration of immune cells in tumor tissues were detected through immunohistochemistry (IHC). These objects were graded as GREM1-positive group (n = 97), GREM1-negative group (n = 53), THBS2-positive group (n = 102) and THBS2-negative group (n = 48) according to the expression of GREM1 and THBS2. The correlation between the expression of GREM1 and THBS2 with immune cell infiltration and clinicopathological indicators was analyzed. Kaplan-Meier survival analysis was adopted to analyze the relationship between the expression of GREM1 and THBS2 and the prognosis in NSCLC tissues. The overall progression-free survival (PFS) of the two groups were compared by log-rank test. The results of IHC showed that the positive expression rate of GREM1 was 64.67% (97/150) in cancer tissues and 36.00% (54/150) in adjacent tissues. The positive expression rate of THBS2 was 68.00% (102/150) in cancer tissues and 25.33% (38/150) in adjacent tissues. The positive expression rate of GREM1 and THBS2 in cancer tissues was both much higher than that in adjacent tissues (P < 0.01). GREM1-positive group had much higher proportion of tumor diameter ≥ 2cm, stage III-IV and lymph-node metastasis than GREM1-negative group (P < 0.05). THBS2-positive group had markedly higher proportion of tumor diameter ≥ 2cm, stage III-IV, lymph-node metastasis and high differentiation than THBS2-negative group (P < 0.01). GREM1-positive group had much higher level of CD3 + T, and sharply lower level of CD8 + T and CD11c + DCs than GREM1-negative group (P < 0.01). THBS2-positive group had much higher level of CD3 + T, and sharply lower level of CD8 + T and CD11c + DCs than THBS2-negative group (P < 0.01). According to Kaplan-Meier survival analysis, the overall median progression-free survival (PFS) was 7.45months. Log-rank test showed that NSCLC patients with positive GREM1 and THBS2 had much shorter PFS than negative patients (P < 0.01). Log-rank test showed that the expression of GREM1 and THBS2 was related to the PFS of patients (P < 0.01). GREM1 and THBS2 were highly expressed in NSCLC tissues and acted as pro-oncogenes in the development and progression of NSCLC, which aggravated the disease by mediating immune cell infiltration.

Adipokine gremlin-1 promotes hepatic steatosis via upregulation of ER stress by suppressing autophagy-mediated signaling.

Gremlin-1 (GR1) is a novel adipokine that is highly expressed in human adipocytes and has been shown to inhibit the BMP2/4-TGFb signaling pathway. It has an effect on insulin sensitivity. Elevated levels of Gremlin have been shown to lead to insulin resistance in skeletal muscle, adipocytes, and hepatocytes. In this study, we investigated the effect of GR1 on hepatic lipid metabolism under hyperlipidemic conditions and explored the molecular mechanisms associated with GR1 by in vitro and in vivo studies. We found that palmitate increased GR1 expression in visceral adipocytes. Recombinant GR1 increased lipid accumulation, lipogenesis, and ER stress markers in cultured primary hepatocytes. Treatment with GR1 increased EGFR expression and mTOR phosphorylation and reduced autophagy markers. EGFR or rapamycin siRNA reduced the effects of GR1 on lipogenic lipid deposition and ER stress in cultured hepatocytes. Administration of GR1 via the tail vein induced lipogenic proteins and ER stress while suppressing autophagy in the livers of experimental mice. Suppression of GR1 by in vivo transfection reduced the effects of a high-fat diet on hepatic lipid metabolism, ER stress, and autophagy in mice. These results suggest that the adipokine GR1 promotes hepatic ER stress due to the impairment of autophagy, ultimately causing hepatic steatosis in the obese state. The current study demonstrated that targeting GR1 may be a potential therapeutic approach for treating metabolic diseases, including metabolic-associated fatty liver disease (MAFLD).

Long noncoding RNA long intergenic non-protein-coding RNA 173 contributes to nasopharyngeal carcinoma progression by regulating microRNA-765/Gremlin 1 pathway.

Long intergenic non-protein-coding RNA 173 (LINC00173) executes vital functions in various cancers. Nevertheless, its role and expression in nasopharyngeal carcinoma (NPC) have yet to be investigated. Here, we investigated its effects on the malignancy characteristics of NPC and elucidated the potential molecular mechanism of LINC00173 in NPC progression. Quantitative real-time reverse transcription-PCR (qRT-PCR) and immunoblotting were conducted to estimate the LINC00173, microRNA-765 (miR-765), and Gremlin 1 (GREM1) expressions in NPC cells and tissues. Cell counting kit-8 (CCK8), colony formation, and wound healing experiments were done to evaluate the proliferation, growth, and migration of NPC cells, respectively. The tumorous growth of NPC cells in vivo was assessed through the xenograft tumor experiment. Furthermore, the interactions among miR-765, LINC00173, and GREM1 were investigated through bioinformatics analyses, luciferase reporter and RNA immunoprecipitation chip assays. An upregulated LINC00173 expression was found in NPC cell lines and tissues. The functional experiments uncovered that its downregulation repressed NPC cell proliferation, growth, and migration. In addition, LINC00173 knockdown hampered the NPC cells' tumorous growth in vivo. These effects could partially be reversed by downregulating miR-765. GREM1 is a downstream target of miR-765. GREM1 knockdown could repress the proliferation, growth, and migration of NPC cells. Nonetheless, these anti-tumor effects could be abolished by miR-765 downregulation. Mechanistically, LINC00173 increased the expression of GREM1 by binding with miR-765. LINC00173 functions as an oncogenic factor by binding with miR-765 to promote the progression of NPC via GREM1 upregulation. This study provides a novel insight into the molecular mechanisms involved in NPC progression.

Loss of bone morphogenetic protein signaling in fibroblasts results in CXCL12-driven serrated polyp development

Mutations in Bone Morphogenetic Protein (BMP) Receptor (BMPR)1A and SMAD4 are detected in 50% of juvenile polyposis syndrome (JPS) patients, who develop stroma-rich hamartomatous polyps. The established role of stromal cells in regulating BMP activity in the intestine implies a role for stromal cells in polyp development. We used conditional Cre-LoxP mice to investigate how specific loss of BMPR1A in endothelial cells, fibroblasts, or myofibroblasts/smooth muscle cells affects intestinal homeostasis. Selective loss of BMPR1A in fibroblasts causes severe histological changes in the intestines with a significant increase in stromal cell content and epithelial cell hyperproliferation, leading to numerous serrated polyps. This phenotype suggests that crucial changes occur in the fibroblast secretome that influences polyp development. Analyses of publicly available RNA expression databases identified CXCL12 as a potential candidate. RNAscope in situ hybridization showed an evident increase of Cxcl12-expressing fibroblasts. In vitro, stimulation of fibroblasts with BMPs resulted in downregulation of CXCL12, while inhibition of the BMP pathway resulted in gradual upregulation of CXCL12 over time. Moreover, neutralization of CXCL12 in vivo in the fibroblast-specific BMPR1A KO mice resulted in a significant decrease in polyp formation. Finally, in CRC patient specimens, mRNA-expression data showed that patients with high GREMLIN1 and CXCL12 expression had a significantly poorer overall survival. Significantly higher GREMLIN1, NOGGIN, and CXCL12 expression were detected in the Consensus Molecular Subtype 4 (CMS4) colorectal cancers, which are thought to arise from serrated polyps. Taken together, these data imply that fibroblast-specific BMP signaling–CXCL12 interaction could have a role in the etiology of serrated polyp formation.

A Novel Role for Biomechanical Forces in the Pathogenesis of Idiopathic Constipation

INTRODUCTION: Chronic constipation is a common gastrointestinal disorder, but an anatomic or physiologic cause is identified in only 5% of patients. Surgery to remove chronically dilated segments of intestine is offered as a last resort. Our goal is to understand how the intestinal microenvironment is affected by biomechanical forces such as chronic distention in idiopathic constipation. METHODS: To evaluate the effects of biomechanical force on the colon, we used 3 models: (1) colon from wildtype mice was cultured ex vivo for 24 hours with and without distention and extracellular matrix–related gene expression was assayed using reverse transcriptase-polymerase chain reaction; (2) an in vivo mouse model of enteric distention was assessed at 7 to 14 days by immunohistochemistry; and (3) human specimens from pediatric patients who underwent colon resections for chronic idiopathic constipation (n = 27) were histologically evaluated to clinically validate our findings (Figure).FigureRESULTS: Ex vivo and in vivo colon under tension demonstrated increased fibrosis compared with control. Tension resulted in significantly decreased expression of antifibrotic Gremlin-1 and increased expression of profibrotic interleukin-1β. Collagens and matrix metalloproteinases were downregulated while laminins were upregulated. Seventy-seven percent of patients with chronic idiopathic constipation displayed dilated and/or redundant colon on imaging. In surgical specimens, 26% had interstitial fibrosis, 33% had muscular hypertrophy, and 15% had myocyte vacuolization. These histologic findings were also seen in distended mouse colon. CONCLUSION: Chronic intestinal distention led to a profibrotic phenotype in all 3 models. We conclude that mechanically sensitive cells may be affected by chronic distention and contribute to intestinal dysfunction in idiopathic constipation.

GREM1 is a novel serum diagnostic marker and potential therapeutic target for pancreatic ductal adenocarcinoma.

ObjectivePancreatic ductal adenocarcinoma (PDAC) is a highly malignant neoplasm with rising incidence worldwide. Gremlin 1 (GREM1), a regulator of bone morphogenetic protein (BMP) signaling, fine-tunes extensive biological processes, including organ morphology, cellular metabolism, and multiple pathological developments. The roles of GREM1 in PDAC remain unknown.MethodsVarieties of public databases and online software were employed to analyze the expressions at transcription and protein levels of GREM1 in multiple malignant neoplasms including PDAC, and in addition, its potential pro-tumoral functions in PDAC were further evaluated. A total of 340 serum samples of pancreatic disease, including PDAC, low-grade malignant pancreatic neoplasm, benign pancreatic neoplasm, pancreatitis, and 132 healthy controls, were collected to detect GREM1. The roles of serum GREM1 in the diagnosis and prediction of survival of PDAC after radical resection were also analyzed.ResultsBioinformatics analyses revealed that GREM1 was overexpressed in PDAC and predicted a poorer survival in PDAC. A higher protein level of GREM1 in PDAC correlated with stroma formation and immunosuppression by recruiting varieties of immunosuppressive cells, including T regulatory cells (Tregs), M2 macrophages, myeloid-derived suppressor cells (MDSCs), and exhaustion T cells into the tumor microenvironment. A higher level of serum GREM1 was observed in PDAC patients, compared to healthy control (p < 0.001). Serum GREM1 had a good diagnostic value (area under the curve (AUC) = 0.718, p < 0.001), and its combination with carbohydrate antigen 199 (CA199) achieved a better diagnostic efficacy (AUC = 0.914, p < 0.001), compared to CA199 alone. The cutoff value was calculated by receiver operating characteristic (ROC) analysis, and PDAC patients were divided into two groups of low and high GREM1. Logistic analyses showed serum GREM1 positively correlated with tumor size (hazard ratio (HR) = 7.097, p = 0.032) and histopathological grades (HR = 2.898, p = 0.014). High-level serum GREM1 (1,117.8 pg/ml) showed a shorter postoperative survival (p = 0.0394).ConclusionHigher intra-tumoral expression of GREM1 in PDAC contributes to tumor stroma and immunosuppressive tumor microenvironment, presenting its therapeutic potential. High-level serum GREM1 predicts poorer survival after resection. A combination of serum CA199 and GREM1 shows a stronger diagnostic efficacy in PDAC.

Gremlin-1 Promotes Colorectal Cancer Cell Metastasis by Activating ATF6 and Inhibiting ATF4 Pathways.

Cancer cell survival, function and fate strongly depend on endoplasmic reticulum (ER) proteostasis. Although previous studies have implicated the ER stress signaling network in all stages of cancer development, its role in cancer metastasis remains to be elucidated. In this study, we investigated the role of Gremlin-1 (GREM1), a secreted protein, in the invasion and metastasis of colorectal cancer (CRC) cells in vitro and in vivo. Firstly, public datasets showed a positive correlation between high expression of GREM1 and a poor prognosis for CRC. Secondly, GREM1 enhanced motility and invasion of CRC cells by epithelial–mesenchymal transition (EMT). Thirdly, GREM1 upregulated expression of activating transcription factor 6 (ATF6) and downregulated that of ATF4, and modulation of the two key players of the unfolded protein response (UPR) was possibly through activation of PI3K/AKT/mTOR and antagonization of BMP2 signaling pathways, respectively. Taken together, our results demonstrate that GREM1 is an invasion-promoting factor via regulation of ATF6 and ATF4 expression in CRC cells, suggesting GREM1 may be a potential pharmacological target for colorectal cancer treatment.