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

BACKGROUND: Colorectal 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. METHODS: Bioinformatics 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. RESULTS: We 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. CONCLUSION: These 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.

SHH regulates penile morphology and smooth muscle through a mechanism involving BMP4 and GREM1.

BACKGROUND: The cavernous nerve (CN) is frequently damaged in prostatectomy and diabetic patients with erectile dysfunction (ED), initiating changes in penile morphology including an acute and intense phase of apoptosis in penile smooth muscle and increased collagen, which alter penile architecture and make corpora cavernosa smooth muscle less able to relax in response to neurotransmitters, resulting in ED. AIM: Sonic hedgehog (SHH) is a critical regulator of penile smooth muscle, and SHH treatment suppresses penile remodeling after CN injury through an unknown mechanism; we examine if part of the mechanism of how SHH preserves smooth muscle after CN injury involves bone morphogenetic protein 4 (BMP4) and gremlin1 (GREM1). METHODS: Primary cultures of smooth muscle cells were established from prostatectomy, diabetic, hypertension and Peyronie's (control) (N = 18) patients. Cultures were characterized by ACTA2, CD31, P4HB, and nNOS immunohistochemical analysis. Patient smooth muscle cell growth was quantified in response to BMP4 and GREM1 treatment. Adult Sprague Dawley rats underwent 1 of 3 surgeries: (1) uninjured or CN-injured rats were treated with BMP4, GREM1, or mouse serum albumin (control) proteins via Affi-Gel beads (N = 16) or peptide amphiphile (PA) (N = 26) for 3 and 14 days, and trichrome stain was performed; (2) rats underwent sham (N = 3), CN injury (N = 9), or CN injury and SHH PA treatment for 1, 2, and 4 days (N = 9). OUTCOMES: Western analysis for BMP4 and GREM1 was performed; (3) rats were treated with 5E1 SHH inhibitor (N = 6) or IgG (control; N = 6) for 2 and 4 days, and BMP4 and GREM1 localization was examined. Statistics were performed by analysis of variance with Scheffé's post hoc test. RESULTS: BMP4 increased patient smooth muscle cell growth, and GREM1 decreased growth. In rats, BMP4 treatment via Affi-Gel beads and PA increased smooth muscle at 3 and 14 days of treatment. GREM1 treatment caused increased collagen and smooth muscle at 3 days, which switched to primarily collagen at 14 days. CN injury increased BMP4 and GREM1, while SHH PA altered Western band size, suggesting alternative cleavage and range of BMP4 and GREM1 signaling. SHH inhibition in rats increased BMP4 and GREM1 in fibroblasts. CLINICAL IMPLICATIONS: Understanding how SHH PA preserves and regenerates penile morphology after CN injury will aid development of ED therapies. STRENGTHS AND LIMITATIONS: SHH treatment alters BMP4 and GREM1 localization and range of signaling, which can affect penile morphology. CONCLUSION: Part of the mechanism of how SHH regulates corpora cavernosa smooth muscle involves BMP4 and GREM1.

BMP4 and GREM1 are targets of SHH signaling and downstream regulators of collagen in the penis.

BACKGROUND: Cavernous nerve (CN) injury, caused by prostatectomy and diabetes, initiates a remodeling process (smooth muscle apoptosis and increased collagen) in the corpora cavernosa of the penis of patients and animal models that is an underlying cause of erectile dysfunction (ED), and the Sonic hedgehog (SHH) pathway plays an essential role in the response of the penis to denervation, as collagen increases with SHH inhibition and decreases with SHH treatment. AIM: We examined if part of the mechanism of how SHH prevents penile remodeling and increased collagen with CN injury involves bone morphogenetic protein 4 (BMP4) and gremlin1 (GREM1) and examined the relationship between SHH, BMP4, GREM1, and collagen in penis of ED patients and rat models of CN injury, SHH inhibition, and SHH, BMP4, and GREM1 treatment. METHODS: Corpora cavernosa of Peyronie's disease (control), prostatectomy, and diabetic ED patients were obtained (N = 30). Adult Sprague Dawley rats (n = 90) underwent (1) CN crush (1-7 days) or sham surgery; (2) CN injury and BMP4, GREM1, or mouse serum albumin (control) treatment via Affi-Gel beads or peptide amphiphile (PA) for 14 days; (3) 5E1 SHH inhibitor, IgG, or phosphate-buffered saline (control) treatment for 2 to 4 days; or (4) CN crush with mouse serum albumin or SHH for 9 days. OUTCOMES: Immunohistochemical and Western analysis for BMP4 and GREM1, and collagen analysis by hydroxyproline and trichrome stain were performed. RESULTS: BMP4 and GREM1 proteins were identified in corpora cavernosa smooth muscle of prostatectomy, diabetic, and Peyronie's patients, and in rat smooth muscle, sympathetic nerve fibers, perineurium, blood vessels, and urethra. Collagen decreased 25.4% in rats with CN injury and BMP4 treatment (P = .02) and increased 61.3% with CN injury and GREM1 treatment (P = .005). Trichrome stain showed increased collagen in rats treated with GREM1. Western analysis identified increased BMP4 and GREM1 in corpora cavernosa of prostatectomy and diabetic patients, and after CN injury (1-2 days) in our rat model. Localization of BMP4 and GREM1 changed with SHH inhibition. SHH treatment increased the monomer form of BMP4 and GREM1, altering their range of signaling. CLINICAL IMPLICATIONS: A better understanding of penile remodeling and how fibrosis occurs with loss of innervation is essential for development of novel ED therapies. STRENGTHS AND LIMITATIONS: The relationship between SHH, BMP4, GREM1, and collagen is complex in the penis. CONCLUSION: BMP4 and GREM1 are downstream targets of SHH that impact collagen and may be useful in collaboration with SHH to prevent penile remodeling and ED.

Demethyleneberberine Alleviates Pulmonary Fibrosis through Disruption of USP11 Deubiquitinating GREM1.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a fatal and chronic interstitial lung disease. Intricate pathogenesis of pulmonary fibrosis and only two approved medications with side effects and high cost bring us the challenge of fully understanding this lethal disease and urgency to find more safe and low-cost therapeutic alternatives. PURPOSE: Demethyleneberberine (DMB) has been demonstrated to have various anti-inflammatory, antioxidant, antifibrosis and anti-cancer bioactivities. The objective of this study was to evaluate the effect of DMB on pulmonary fibrosis and investigate the mechanism. METHODS: Bleomycin (BLM)-induced pulmonary fibrosis was established in mice to evaluate the antifibrotic effect of DMB in vivo. A549 and MRC5 cells were used to evaluate the effect of DMB on epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transition (FMT) in vitro. High throughput sequencing, biotin-avidin system and site-directed mutagenesis were applied to explore the mechanism of DMB in alleviating pulmonary fibrosis. RESULTS: DMB alleviated BLM-induced pulmonary fibrosis in vivo by improving the survival state of mice, significantly reducing pulmonary collagen deposition and oxidative stress and improving lung tissue morphology. Meanwhile, DMB was demonstrated to inhibit epithelial-mesenchymal transition (EMT) and fibroblast-myofibroblast transition (FMT) in vitro. High throughput sequencing analysis indicated that GREM1, a highly upregulated profibrotic mediator in IPF and BLM-induced pulmonary fibrosis, was significantly downregulated by DMB. Furthermore, USP11 was revealed to be involved in the deubiquitination of GREM1 in this study and DMB promoted the ubiquitination and degradation of GREM1 by inhibiting USP11. Remarkably, DMB was demonstrated to selectively bind to the Met776 residue of USP11, leading to disruption of USP11 deubiquitinating GREM1. In addition, DMB presented an equivalent antifibrotic effect at a lower dose compared with pirfenidone and showed no obvious toxicity or side effects. CONCLUSIONS: This study revealed that USP11/GREM1 could be a potential target for IPF management and identified that DMB could promote GREM1 degradation by inhibiting USP11, thereby alleviating pulmonary fibrosis.

Unravelling the role of HAS2, GREM1, and PTGS2 gene expression in cumulus cells: implications for human oocyte development competency - a systematic review and integrated bioinformatic analysis.

The leading indicator for successful outcomes in in-vitro fertilization (IVF) is the quality of gametes in oocytes and sperm. Thus, advanced research aims to highlight the parameter in assessing these qualities - DNA fragmentation in sperm and oocyte development capacity (ODC) via evaluation of microenvironments involving its maturation process. Regarding oocytes, most evidence reveals the role of cumulus cells as non-invasive methods in assessing their development competency, mainly via gene expression evaluation. Our review aims to consolidate the evidence of GDF-9 derivatives, the HAS2, GREM1, and PTGS2 gene expression in cumulus cells used as ODC markers in relevant publications and tailored to current IVF outcomes. In addition to that, we also added the bioinformatic analysis in our review to strengthen the evidence aiming for a better understanding of the pathways and cluster of the genes of interest - HAS2, GREM1, and PTGS2 in cumulus cell level. Otherwise, the current non-invasive method can be used in exploring various causes of infertility that may affect these gene expressions at the cumulus cell level. Nevertheless, this method can also be used in assessing the ODC in various cohorts of women or as an improvement of markers following targeted tools or procedures by evaluating the advancement of these gene expressions following the targeted intervention.

Human intestinal organoid-derived PDGFRα + mesenchymal stroma enables proliferation and maintenance of LGR4 + epithelial stem cells.

BACKGROUND: Intestinal epithelial cells derived from human pluripotent stem cells (hPSCs) are generally maintained and cultured as organoids in vitro because they do not exhibit adhesion when cultured. However, the three-dimensional structure of organoids makes their use in regenerative medicine and drug discovery difficult. Mesenchymal stromal cells are found near intestinal stem cells in vivo and provide trophic factors to regulate stem cell maintenance and proliferation, such as BMP inhibitors, WNT, and R-spondin. In this study, we aimed to use mesenchymal stromal cells isolated from hPSC-derived intestinal organoids to establish an in vitro culture system that enables stable proliferation and maintenance of hPSC-derived intestinal epithelial cells in adhesion culture. METHODS: We established an isolation protocol for intestinal epithelial cells and mesenchymal stromal cells from hPSCs-derived intestinal organoids and a co-culture system for these cells. We then evaluated the intestinal epithelial cells and mesenchymal stromal cells' morphology, proliferative capacity, chromosomal stability, tumorigenicity, and gene expression profiles. We also evaluated the usefulness of the cells for pharmacokinetic and toxicity studies. RESULTS: The proliferating intestinal epithelial cells exhibited a columnar form, microvilli and glycocalyx formation, cell polarity, and expression of drug-metabolizing enzymes and transporters. The intestinal epithelial cells also showed barrier function, transporter activity, and drug-metabolizing capacity. Notably, small intestinal epithelial stem cells cannot be cultured in adherent culture without mesenchymal stromal cells and cannot replaced by other feeder cells. Organoid-derived mesenchymal stromal cells resemble the trophocytes essential for maintaining small intestinal epithelial stem cells and play a crucial role in adherent culture. CONCLUSIONS: The high proliferative expansion, productivity, and functionality of hPSC-derived intestinal epithelial cells may have potential applications in pharmacokinetic and toxicity studies and regenerative medicine.

GREM1 knockdown regulates the proliferation, apoptosis and EMT of benign prostatic hyperplasia by suppressing the STAT3/c-Myc signaling.

BACKGROUND: Gremlin 1 (GREM1) has been reported to be highly expressed in prostate hyperplasia tissues. However, the role and molecular mechanism of GREM1 in benign prostatic hyperplasia (BPH) is still unclear. METHODS: In this study, expression of GREM1 in BPH-1 cells was detected by western blot assay. Cell counting kit-8 assay was performed to assess cell proliferation. Flow cytometry and western blot were used to assess cell apoptosis and cell cycle. The EMT process was detected by western blot assay and immunofluorescence staining. In addition, colivelin was used as a STAT3 activator and the expressions of STAT3/c-Myc signaling were assessed by western blot assay. RESULTS: The data showed that GREM1 silencing inhibited BPH-1 cell proliferation and promoted cell apoptosis. Moreover, GREM1 silencing repressed the cell cycle progression and the development of EMT. In addition, knockdown of GREM1 suppressed the expression of the STAT3/c-Myc signaling in BPH-1 cells and colivelin treatment rehabilitated this signaling. Moreover, c-Myc overexpression or colivelin reversed the effects of GREM1 silencing on BPH-1 cell proliferation, cell apoptosis, cell cycle, as well as EMT. CONCLUSION: To sum up, GREM1 silencing may alleviate the BPH progress by inhibiting the STAT3/c-Myc signaling.

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.

Association between IRF6, TP63, GREM1 Gene Polymorphisms and Non-Syndromic Orofacial Cleft Phenotypes in Vietnamese Population: A Case-Control and Family-Based Study.

This study aims to identify potential variants in the TP63-IRF6 pathway and GREM1 for the etiology of non-syndromic orofacial cleft (NSOFC) among the Vietnamese population. By collecting 527 case-parent trios and 527 control samples, we conducted a stratified analysis based on different NSOFC phenotypes, using allelic, dominant, recessive and over-dominant models for case-control analyses, and family-based association tests for case-parent trios. Haplotype and linkage disequilibrium analyses were also conducted. IRF6 rs2235375 showed a significant association with an increased risk for non-syndromic cleft lip and palate (NSCLP) and cleft lip with or without cleft palate (NSCL/P) in the G allele, with pallele values of 0.0018 and 0.0003, respectively. Due to the recessive model (p = 0.0011) for the NSCL/P group, the reduced frequency of the GG genotype of rs2235375 was associated with a protective effect against NSCL/P. Additionally, offspring who inherited the G allele at rs2235375 had a 1.34-fold increased risk of NSCL/P compared to the C allele holders. IRF6 rs846810 and a G-G haplotype at rs2235375-rs846810 of IRF6 impacted NSCL/P, with p-values of 0.0015 and 0.0003, respectively. In conclusion, our study provided additional evidence for the association of IRF6 rs2235375 with NSCLP and NSCL/P. We also identified IRF6 rs846810 as a novel marker associated with NSCL/P, and haplotypes G-G and C-A at rs2235375-rs846810 of IRF6 associated with NSOFC.

GREM1, LRPPRC and SLC39A4 as potential biomarkers of intervertebral disc degeneration: a bioinformatics analysis based on multiple microarray and single-cell sequencing data.

BACKGROUND: Low back pain (LBP) has drawn much widespread attention and is a major global health concern. In this field, intervertebral disc degeneration (IVDD) is frequently the focus of classic studies. However, the mechanistic foundation of IVDD is unclear and has led to conflicting outcomes. METHODS: Gene expression profiles (GSE34095, GSE147383) of IVDD patients alongside control groups were analyzed to identify differentially expressed genes (DEGs) in the GEO database. GSE23130 and GSE70362 were applied to validate the yielded key genes from DEGs by means of a best subset selection regression. Four machine-learning models were established to assess their predictive ability. Single-sample gene set enrichment analysis (ssGSEA) was used to profile the correlation between overall immune infiltration levels with Thompson grades and key genes. The upstream targeting miRNAs of key genes (GSE63492) were also analyzed. A single-cell transcriptome sequencing data (GSE160756) was used to define several cell clusters of nucleus pulposus (NP), annulus fibrosus (AF), and cartilaginous endplate (CEP) of human intervertebral discs and the distribution of key genes in different cell clusters was yielded. RESULTS: By developing appropriate p-values and logFC values, a total of 6 DEGs was obtained. 3 key genes (LRPPRC, GREM1, and SLC39A4) were validated by an externally validated predictive modeling method. The ssGSEA results indicated that key genes were correlated with the infiltration abundance of multiple immune cells, such as dendritic cells and macrophages. Accordingly, these 4 key miRNAs (miR-103a-3p, miR-484, miR-665, miR-107) were identified as upstream regulators targeting key genes using the miRNet database and external GEO datasets. Finally, the spatial distribution of key genes in AF, CEP, and NP was plotted. Pseudo-time series and GSEA analysis indicated that the expression level of GREM1 and the differentiation trajectory of NP chondrocytes are generally consistent. GREM1 may mainly exacerbate the degeneration of NP cells in IVDD. CONCLUSIONS: Our study gives a novel perspective for identifying reliable and effective gene therapy targets in IVDD.

GREM1 is a potential biomarker for the progression and prognosis of bladder cancer.

BACKGROUND: Gremlin-1 (GREM1) is a protein closely related to tumor growth, although its function in bladder cancer (BCa) is currently unknown. Our first objective was to study the GREM1 treatment potential in BCa. METHODS: BCa tissue samples were collected for the detection of GREM1 expression using Western blot analysis and Immunofluorescence staining. Association of GREM1 expression with clinicopathology and prognosis as detected by TCGA (The Cancer Genome Atlas) database. The functional investigation was tested by qRT-PCR, western blot analysis, CCK-8, cell apoptosis, wound healing, and transwell assays. The interaction between GREM1 and the downstream PI3K/AKT signaling pathway was assessed by Western blot analysis. RESULTS: GREM1 exhibited high expression in BCa tissues and was linked to poor prognosis. Stable knockdown of GREM1 significantly inhibited BCa cell (T24 and 5637) proliferation, apoptosis, migratory, invasive, as well as epithelial-mesenchymal transition (EMT) abilities. GREM1 promotes the progression in BCa via PI3K/AKT signaling pathway. CONCLUSION: Findings demonstrate that the progression-promoting effect of GREM1 in BCa, providing a novel biomarker for BCa-targeted therapy.

Nicotine exacerbates diabetic nephropathy through upregulation of Grem1 expression.

BACKGROUND: Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Clinical reports indicate that smoking is a significant risk factor for chronic kidney disease, and the tobacco epidemic exacerbates kidney damage in patients with DN. However, the underlying molecular mechanisms remain unclear. METHOD: In the present study, we used a diabetic mouse model to investigate the molecular mechanisms for nicotine-exacerbated DN. Twelve-week-old female mice were injected with streptozotocin (STZ) to establish a hyperglycemic diabetic model. After four months, the control and hyperglycemic diabetic mice were further divided into four groups (control, nicotine, diabetic mellitus, nicotine + diabetic mellitus) by intraperitoneal injection of nicotine or PBS. After two months, urine and blood were collected for kidney injury assay, and renal tissues were harvested for further molecular assays using RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry. In vitro studies, we used siRNA to suppress Grem1 expression in human podocytes. Then we treated them with nicotine and high glucose to compare podocyte injury. RESULT: Nicotine administration alone did not cause apparent kidney injury, but it significantly increased hyperglycemia-induced albuminuria, BUN, plasma creatinine, and the kidney tissue mRNA expression of KIM-1 and NGAL. Results from RNA-seq analysis, real-time PCR, Western blot, and immunohistochemistry analysis revealed that, compared to hyperglycemia or nicotine alone, the combination of nicotine treatment and hyperglycemia significantly increased the expression of Grem1 and worsened DN. In vitro experiments, suppression of Grem1 expression attenuated nicotine-exacerbated podocyte injury. CONCLUSION: Grem1 plays a vital role in nicotine-exacerbated DN. Grem1 may be a potential therapeutic target for chronic smokers with DN.

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.

OBJECTIVE: 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. METHODS: 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. RESULTS: 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 ≥ 2 cm, stage III-IV and lymph-node metastasis than GREM1-negative group (P < 0.05). THBS2-positive group had markedly higher proportion of tumor diameter ≥ 2 cm, 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 7.45 months. 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). CONCLUSION: 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.

The autocrine glycosylated-GREM1 interacts with TGFB1 to suppress TGFß/BMP/SMAD-mediated EMT partially by inhibiting MYL9 transactivation in urinary carcinoma.

PURPOSE: Urothelial carcinoma (UC) is a common disease in developed counties. This study aimed to identify autocrine roles and signaling pathways of gremlin 1, DAN family BMP antagonist (GREM1), which inhibits tumor growth and epithelial-mesenchymal transition (EMT) in UC. METHODS: Systematic in vitro and in vivo studies using genetic engineering, different urinary bladder urothelial carcinoma (UBUC)-derived cell lines, and mouse models were performed, respectively. Further, primary upper tract urothelial carcinoma (UTUC) and UBUC specimens were evaluated by immunohistochemistry. RESULTS: GREM1 protein levels conferred better disease-specific and metastasis-free survival rates and played an independent prognostic factor in UTUC and UBUC. Hypermethylation is the primary cause of low GREM1 levels. In different UBUC-derived cell lines, the autocrine/secreted and glycosylated GREM1 interacted with transforming growth factor beta 1 (TGFB1) and inhibited TGFß/BMP/SMAD signaling and myosin light chain 9 (MYL9) transactivation, subsequently cell proliferation and epithelial-mesenchymal transition (EMT). Secreted and glycosylated GREM1 also suppressed tumor growth, metastasis, and MYL9 levels in the mouse model. Instead, cytosolic GREM1 promoted cell proliferation and EMT by activating the tumor necrosis factor (TNF)/AKT/nuclear factor kappa B (NFκB) axis. CONCLUSIONS: Clinical associations, animal models, and in vitro indications provided solid evidence to show that the epithelial autocrine GREM1 is a novel tumor suppressor in UCs. The glycosylated-GREM1 hampered cell proliferation, migration, invasion, and in vitro angiogenesis through interaction with TGFB1 to inactivate TGFß/BMP/SMAD-mediated EMT in an autocrine manner.

Regulation of Cervical Cancer Development by a Novel Circ_0000212/miR-1236-3p/GREM1 ceRNA Crosstalk.

Circular RNAs (circRNAs) possess important functions in cervical carcinogenesis by operating as competing endogenous RNAs (ceRNAs). Our preliminary bioinformatics predicted the potential circ_0000212/microRNA (miR)-1236-3p/gremlin 1 (GREM1) ceRNA crosstalk. Thus, we further elucidated whether the novel ceRNA crosstalk can participate in cervical cancer development. Circ_0000212, miR-1236-3p and GREM1 were quantified by real-time quantitative polymerase chain reaction (qPCR) and immunoblotting. 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and tube formation assay were performed to assess cell proliferation, apoptosis and tube formation, respectively. Transwell assay was used to detect cell migration and invasion. Mouse xenografts were established to evaluate the role of circ_0000212 in vivo. Dual-luciferase reporter assay was performed to verify the direct relationship between miR-1236-3p and circ_0000212 or GREM1. Circ_0000212 expression was elevated in human cervical cancer. Silencing of endogenous circ_0000212 hindered cancer cell proliferation, motility and invasion and induced apoptosis, as well as diminished the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. Circ_0000212 silencing also weakened tumor growth in vivo. Mechanistically, circ_0000212 directly bound to miR-1236-3p, and downregulation of miR-1236-3p reversed these effects of circ_0000212 silencing on cell malignant phenotypes and HUVEC tube formation. GREM1 was a direct miR-1236-3p target, and its expression was regulated by circ_0000212 through miR-1236-3p. Moreover, miR-1236-3p upregulation impeded cancer cell malignant phenotypes and HUVEC tube formation by targeting GREM1. Our findings identify a novel ceRNA regulatory network, circ_0000212/miR-1236-3p/GREM1 axis, in cervical carcinogenesis, and provide potential targets that can be explored for therapeutic interventions.

TRIM28 secures skeletal stem cell fate during skeletogenesis by silencing neural gene expression and repressing GREM1/AKT/mTOR signaling axis.

Long bones are generated by mesoderm-derived skeletal progenitor/stem cells (SSCs) through endochondral ossification, a process of sequential chondrogenic and osteogenic differentiation tightly controlled by the synergy between intrinsic and microenvironment cues. Here, we report that loss of TRIM28, a transcriptional corepressor, in mesoderm-derived cells expands the SSC pool, weakens SSC osteochondrogenic potential, and endows SSCs with properties of ectoderm-derived neural crest cells (NCCs), leading to severe defects of skeletogenesis. TRIM28 preferentially enhances H3K9 trimethylation and DNA methylation on chromatin regions more accessible in NCCs; loss of this silencing upregulates neural gene expression and enhances neurogenic potential. Moreover, TRIM28 loss causes hyperexpression of GREM1, which is an extracellular signaling factor promoting SSC self-renewal and SSC neurogenic potential by activating AKT/mTORC1 signaling. Our results suggest that TRIM28-mediated chromatin silencing establishes a barrier for maintaining the SSC lineage trajectory and preventing a transition to ectodermal fate by regulating both intrinsic and microenvironment cues.

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

Objective: Pancreatic 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. Methods: Varieties 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. Results: Bioinformatics 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). Conclusion: Higher 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.

Compound loss of GSDMD and GSDME function is necessary to achieve maximal therapeutic effect in colitis.

Gasdermin D (GSDMD) and gasdermin E (GSDME) perpetuate inflammation by mediating the release of cytokines such as interleukin-1ß (IL-1ß) and IL-18. However, not only are the actions of GSDMD in colitis still controversial, but its interplay with GSDME in the pathogenesis of this disease has not been investigated. We sought to fill these knowledge gaps using the dextran sodium sulfate (DSS) experimental mouse colitis model. DSS ingestion by wild-type mice caused body weight loss as the result of severe gut inflammation, outcomes that were significantly attenuated in Gsdmd -/- or Gsdme -/- mice and nearly fully prevented in Gsdmd -/- ;Gsdme -/- animals. To assess the translational implications of these findings, we tested the efficacy of the active metabolite of US Food and Drug Administration (FDA)-approved disulfiram, which inhibits GSDMD and GSDME function. The severe DSS-induced gut toxicity was significantly decreased in mice treated with the inhibitor. Collectively, our findings indicate that disruption of the function of both GSDMD and GSDME is necessary to achieve maximal therapeutic effect in colitis.

Exosomal miR-150 derived from BMSCs inhibits TNF-α-mediated osteoblast apoptosis in osteonecrosis of the femoral head by GREM1/NF-κB signaling.

Aim: The purpose of this study was to investigate the functions of exosomal miR-150 derived from bone marrow mesenchymal stem cells in osteonecrosis of the femoral head (ONFH). Materials & methods: Cell viability and apoptosis were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry. Alizarin red staining was performed to detect calcium deposits. A rat model was established to assess the effects of exosomal miR-150 on ONFH in vivo. Results: Exosomes or exosomal miR-150 derived from bone marrow mesenchymal stem cells inhibited TNF-α-induced osteoblast apoptosis and promoted osteogenic differentiation and autophagy. Exosomal miR-150 suppressed apoptosis and induced autophagy in TNF-α-treated osteoblasts by regulating the GREM1/NF-κB axis. Exosomal miR-150 also improved the pathological features of ONFH in vivo. Conclusion: Exosomal miR-150 alleviates ONFH by mediating the GREM1/NF-κB axis. This study provides a potential therapeutic strategy for ONFH.

Osteonecrosis of the femoral head (ONFH) is an orthopedic disease that frequently occurs in young adults aged less than 50 years. At present, there is no widely accepted curative surgical procedure or drug therapy for this disease. Bone marrow mesenchymal stem cells (BMSCs) play a key role in the progression of ONFH. BMSC-derived exosomes refer to small membrane vesicles that can transfer proteins, miRNAs and mRNAs, which are closely related to the development of ONFH. This study showed that exosomal miRNA-150 derived from BMSCs inhibited TNF-α-induced osteoblast apoptosis and promoted osteogenic differentiation and autophagy by regulating the GREM1/NF-κB axis. In addition, exosomal miRNA-150 alleviated the symptoms of ONFH in rats.