Expression Of GDF15 Research Articles

Aldehyde-driven transcriptional stress triggers an anorexic DNA damage response.

Endogenous DNA damage can perturb transcription, triggering a multifaceted cellular response that repairs the damage, degrades RNA polymerase II and shuts down global transcription1-4. This response is absent in the human disease Cockayne syndrome, which iscaused by loss of the Cockayne syndrome A (CSA) or CSB proteins5-7. However, the source of endogenous DNA damage and how this leads to the prominent degenerative features of this disease remain unknown. Here we find that endogenous formaldehyde impedes transcription, with marked physiological consequences. Mice deficient in formaldehyde clearance (Adh5-/-) and CSB (Csbm/m; Csb is also known as Ercc6) develop cachexiaand neurodegeneration, and succumb to kidney failure, features that resemble human Cockayne syndrome. Using single-cell RNAsequencing, we find that formaldehyde-driven transcriptional stress stimulates the expression of the anorexiogenic peptide GDF15 by a subset of kidney proximal tubule cells. Blocking this response with an anti-GDF15 antibody alleviates cachexia in Adh5-/-Csbm/m mice. Therefore, CSB provides protection to the kidney and brain against DNA damage caused by endogenous formaldehyde, while also suppressing an anorexic endocrine signal. The activation of this signal might contribute to the cachexia observed in Cockayne syndrome as wellas chemotherapy-induced anorectic weight loss. A plausible evolutionary purpose for such a response is to ensure aversion to genotoxins in food.

GDF15 expression in glioma is associated with malignant progression, immune microenvironment, and serves as a prognostic factor.

AimsGrowth differentiation factor 15 (GDF15) is involved in lots of crucial inflammatory and immune response. The clinical and immune features for GDF15 in glioma have not been specifically investigated so far.MethodsGene expression profiles obtained from public glioma datasets were used to explore the biological function of GDF15 and its impact on immune microenvironment. Interference with GDF15 in several glioma cell lines to verify its functions in vitro. Survival data were used for the survival analysis and establishment of a nomogram predictive model.ResultsGDF15 was up‐regulated in various malignant phenotypes of glioma. Function analysis and in vitro experiments revealed that GDF15 was associated with malignant progression and NF‐κB pathway. GDF15 was closely correlated to inflammatory response, infiltrating immune cells, and immune checkpoint molecules, especially in lower grade glioma (LGG). High expression level of GDF15 predicted poor survival in LGG, while the effect on glioblastoma (GBM) was not significant. A nomogram predictive model combining GDF15 and other prognostic factors was constructed and showed ideal predictive performance.ConclusionsGDF15 could serve as an interesting prognostic biomarker for LGG. Regulating the expression of GDF15 may help solve the dilemma of immunotherapy in glioma.

Negative Regulators of Inflammation Response to the Dynamic Expression of Cytokines in DF-1 and MDCK Cells Infected by Avian Influenza Viruses.

The H5N1 and H9N2 avian influenza viruses (AIVs) seriously endanger the poultry industry and threaten human health. Characteristic inflammatory responses caused by H5N1 and H9N2 AIVs in birds and mammals result in unique clinical manifestations. The role of anti-inflammatory regulators, PTX3, Del-1, and GDF-15, in H5N1 and H9N2-AIV-mediated inflammation in birds and mammals has not yet been verified. Here, the expression of PTX3, Del-1, and GDF-15 in DF-1 and MDCK cells infected with H5N1 and H9N2 AIVs and their effect on inflammatory cytokines were analyzed. Infection with both AIVs increased PTX3, Del-1, and GDF-15 expression in DF-1 and MDCK cells. Infection with H9N2 or H5N1 AIV in DF-1 and MDCK cells with overexpression of all three factors, either alone or in combination, inhibited the expression of tested inflammatory cytokines. Furthermore, co-expression of PTX3, Del-1, and GDF-15 enhanced the inhibition, irrespective of the cell line. The findings from this study offer insight into the pathogenic differences between H5N1 and H9N2 AIVs in varied hosts. Moreover, our findings can be used to help screen for host-specific anti-inflammatory agents.

Novel Insights Into Cellular Changes in HPV8-E7 Positive Keratinocytes: A Transcriptomic and Proteomic Analysis.

Human papillomavirus type 8 (HPV8) is associated with the development of non-melanoma skin cancer. In the past we already delved into the mechanisms involved in keratinocyte invasion, showing that the viral E7 oncoprotein is a key player that drives invasion of basal keratinocytes controlled by the extracellular protein fibronectin. To unravel further downstream effects in E7 expressing keratinocytes we now aimed at characterizing gene and protein/phosphoprotein alterations to narrow down on key cellular targets of HPV8-E7. We now show that gene expression of GADD34 and GDF15 are strongly activated in the presence of E7 in primary human keratinocytes. Further analyses of fibronectin-associated factors led to the identification of the Src kinase family members Fyn and Lyn being aberrantly activated in the presence of HPV8-E7. Phospho-proteomics further revealed that E7 not only targets cell polarity and cytoskeletal organization, but also deregulates the phosphorylation status of nuclear proteins involved in DNA damage repair and replication. Many of these differentially phosphorylated proteins turned out to be targets of Fyn and Lyn. Taken together, by using unbiased experimental approaches we have now arrived at a deeper understanding on how fibronectin may affect the signaling cascades in HPV8 positive keratinocytes, which may be key for skin tumorigenesis and that may also aid in the development of novel therapeutic approaches for betaHPV-mediated cancers.

Fragile X-Related Protein 1 (FXR1) Promotes Trophoblast Migration at Early Pregnancy via Downregulation of GDF-15 Expression

Fragile X-related protein 1 (FXR1) is an RNA-binding protein that can regulate specific mRNA decay in cells. Our previous study showed that FXR1 expression was significantly decreased in trophoblasts from patients with unexplained recurrent spontaneous abortion (RSA); however, the role of FXR1 in trophoblast function during early placenta development has not been fully elucidated. In this study, we found that knockdown of FXR1 using siRNA effectively inhibited the migration of HTR-8 cells and extravillous trophoblast (EVT) outgrowth in an ex vivo extravillous explant culture model. Furthermore, through analysis of a panel of cytokines, we found that the GDF-15 protein was upregulated after knockdown of FXR1 in HTR-8/SVneo cells. This was further confirmed by western blotting and immunofluorescence in HTR-8/SVneo cells and an extravillous explant. Our data also showed that FXR1 expression was downregulated and GDF-15 was upregulated in chorionic villous tissues from RSA patients compared with those from healthy controls (HCs). Further, immunohistochemistry showed a strong expression of GDF-15 in chorionic villous tissue in the RSA group, which was mainly distributed in villous trophoblasts (CTBs) and syncytiotrophoblasts (STBs). Moreover, knockdown of GDF-15 enhanced the migration of HTR-8 cells, while overexpression of GDF-15 using plasmid or treatment with recombinant human GDF-15 protein inhibited trophoblast migration. Importantly, RNA-binding protein immunoprecipitation showed that FXR1 directly bound to the 3′-UTR of GDF-15 mRNA to promote GDF-15 mRNA decay. Together, our data provide new insight into the function of FXR1 in human placenta via regulation of GDF-15 expression in trophoblasts and suggest a possible pathological process involved in RSA.

Abstract 1828: AZD8853: A novel antibody targeting GDF15 for immunotherapy refractory tumors

Abstract Immunotherapy has revolutionized patient care, however, the majority of patients with cancer still do not benefit from this treatment modality. This is due to many factors, including a complex tumor microenvironment (TME) that has too few functional effector cells and/or the presence of many inhibitory cells. Understanding how to remodel the TME to potentiate productive immunity against cancer cells is an active area of research. Growth and Differentiation Factor 15 (GDF-15) is a member of the TGF-beta superfamily that is overexpressed by many solid tumors and is implicated in dampening immune responses. The present study was aimed at understanding the role of GDF-15 in tumor immune biology. We show that GDF-15 can inhibit the differentiation and activation of human monocyte-derived dendritic cells (DCs) and prevent T cell activation. Furthermore blockade of GDF-15 by AZD8853, an anti-GDF15 monoclonal antibody, can restore these activities in vitro. Tumors derived from GDF15 knock-out syngeneic cell lines, Renca and MC-38, show 2-3 fold increases in T cells and activated DCs in the TME as compared to tumors derived from isogeneic parental cells. Treatment of mice with anti-GDF15 mAb leads to substantial anti-tumor activity in anti-PD-L1 refractory LL/2 and MBT2 syngeneic tumors with 50% of the animals showing complete tumor regressions. Coupled with this anti-tumor activity, we show that after 2 doses of anti-GDF15 mAb there is an increase in both activated T cells and DCs in the TME. Depletion of T cells, using anti-CD4 and anti-CD8, in mice ablates the anti-tumor activity observed with anti-GDF15 mAb treatment. These results suggest that inhibition of GDF15 by AZD8853 may be an attractive therapeutic strategy for patients with solid tumors that have high expression of GDF15. Citation Format: Elaine Hurt, Suneetha Thomas, Kathy Mulgrew, Stephen Blackmore, James Moynihan, Fiona Cusdin, Roger Dodd, Peter Cariuk, Anna Sigurdardottir, Emily Brannigan, Claire Dobson, Rakesh Kumar, Mark Cobbold. AZD8853: A novel antibody targeting GDF15 for immunotherapy refractory tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1828.

GDF15 Promotes Cardiac Fibrosis and Proliferation of Cardiac Fibroblasts via the MAPK/ERK1/2 Pathway after Irradiation in Rats.

Ionizing radiation exposure is associated with a risk of cardiac fibrosis; however, the underlying molecular mechanism remains unclear. Growth/differentiation factor-15 (GDF15), a fibroblast factor, is a divergent member of the transforming growth factor β superfamily. Next-generation sequencing analyses has revealed that Gdf15 is increased in cardiac fibroblasts during radiation-induced fibrosis. However, the role of Gdf15 in cardiac fibrosis remains unclear. In this study, we demonstrated that the upregulated expression of GDF15 in newborn rat cardiac fibroblasts and adult rats after irradiation could induce fibrosis, which was confirmed by the increased cell proliferation rate and the increased expression of fibrosis markers (Col1α and αSMA) in newborn rat cardiac fibroblasts after transfection with Gdf15 in vitro. Conversely, the downregulation of GDF15 inhibited cardiac fibrosis, as confirmed by G2/M-cell cycle arrest, suppression of cell proliferation, and low levels of Col1α and αSMA expression. We also found that suppressing the expression of Gdf15 in cardiac fibroblasts could lead to a decrease in CDK1 and inhibit phosphorylation of ERK1/2. Thus, GDF15 might promote cardiac fibroblast fibrosis through the MAPK/ERK1/2 pathway and thus contribute to the pathogenesis of radiation-induced heart disease.

DHODH inhibition modulates glucose metabolism and circulating GDF15, and improves metabolic balance

SummaryDihydroorotate dehydrogenase (DHODH) is essential for the de novo synthesis of pyrimidine ribonucleotides, and as such, its inhibitors have been long used to treat autoimmune diseases and are in clinical trials for cancer and viral infections. Interestingly, DHODH is located in the inner mitochondrial membrane and contributes to provide ubiquinol to the respiratory chain. Thus, DHODH provides the link between nucleotide metabolism and mitochondrial function. Here we show that pharmacological inhibition of DHODH reduces mitochondrial respiration, promotes glycolysis, and enhances GLUT4 translocation to the cytoplasmic membrane and that by activating tumor suppressor p53, increases the expression of GDF15, a cytokine that reduces appetite and prolongs lifespan. In addition, similar to the antidiabetic drug metformin, we observed that in db/db mice, DHODH inhibitors elevate levels of circulating GDF15 and reduce food intake. Further analysis using this model for obesity-induced diabetes revealed that DHODH inhibitors delay pancreatic β cell death and improve metabolic balance.

ATF4-mediated GDF15 suppresses LPS-induced inflammation and MUC5AC in human nasal epithelial cells through the PI3K/Akt pathway

AimsGrowth and differentiation factor 15 (GDF15) is a stress-related factor, which implicated in various diseases. This study aimed to investigate the role of GDF15 in LPS-mediated inflammation and to explore the potential underlying molecular mechanisms in human nasal epithelial cells (HNEpCs). Main methodsHNEpCs were treated with LPS. GDF15 loss-of-function and gain-of-function experiments were performed. The expression of GDF15 by quantitative real-time PCR (RT-qPCR). The mRNA levels and secretion of inflammatory cytokines and MUC5AC were assessed by RT-qPCR and ELISA kits. LY294002 (PI3K inhibitor) and 740Y-P (PI3K agonist) were utilized to interfere with PI3k/Akt pathway. The relationship between GDF15 and ATF4 was identified by chromatin immunoprecipitation (ChIP) and luciferase reporter assay. Key findingsWe observed that LPS triggered GDF15 expression. GDF15 ablation reduced the mRNA levels and secretion of inflammatory cytokines. GDF15 silencing led to the reduction of the MUC5AC mRNA level, protein level and secretion in response to LPS. Enhanced expression of GDF15 showed the opposite results. Furthermore, we found that GDF15 deficiency inhibited activation of the PI3K/Akt pathway, LY294002 treatment further enhanced the role of GDF15 suppression in inflammation and MUC5AC expression, while 740Y-P administration partly reversed the biological activities of GDF15 silencing. ATF4 could bind to the promoter of GDF15 and positively regulate GDF15 expression. Depression of ATF4 diminished the secretion of inflammatory cytokines and MUC5AC via regulation of GDF15. SignificanceOur data suggest that GDF15 is regulated by ATF4 and suppresses LPS-induced inflammation and MUC5AC in human nasal epithelial cells through the PI3K/Akt pathway.

Value of Growth/Differentiation Factor 15 in Diagnosis and the Evaluation of Chemotherapeutic Response in Lung Cancer

PurposeThere is a need for efficient, convenient, and inexpensive methods to accurately diagnose the clinical stage of lung cancer and evaluate the efficacy of chemotherapy in patients with lung cancer. Although growth/differentiation factor 15 (GDF)-15 has great potential as a tumor marker, supporting clinical evidence is still lacking. In this study, we aimed to analyze the relationship between serum GDF15 concentration and the clinical characteristics of patients with lung cancer, and to assess the value of GDF15 in the diagnosis and curative effect of chemotherapy. MethodsThe study comprised 160 participants in total, of whom 88 had lung cancer, 31 had pneumonia, and 41 were control subjects. Among the 88 patients with lung cancer, 64 were willing to participate in follow-up chemotherapy-related studies and meet the inclusion criteria. The serum GDF15 concentration in 288 samples (31 cases, pneumonia group samples; 41 cases, control samples; 88 cases, lung cancer group samples; 64 cases, after 1 chemotherapy cycle; and 64 cases, after 2 chemotherapy cycles) with advanced lung cancer were detected by ELISA. The possible correlations between serum GDF15 level and sex, age, height, weight, body mass index, smoking history, diabetes status, and laboratory findings (hemoglobin, prealbumin, and lactate dehydrogenase) were analyzed using parametric and nonparametric tests. Thereafter, the sensitivity of GDF15 in diagnosing lung cancer was calculated. The serum levels of GDF15, carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and cytokeratin 19 fragment (CYFRA) 21-1 were determined in 64 patients with lung cancer, before and after chemotherapy reception. For the evaluation of the efficacy of chemotherapy, receiver operating characteristic curves were plotted. FindingsSerum GDF15 concentration at baseline was significantly higher in the lung cancer group than were those in the pneumonia and control groups (both, P < 0.001). An increased expression of serum GDF15 was significantly correlated with diabetes, anemia, and clinical stage (tumor size, nodal involvement, and presence/absence of metastasis). After 2 cycles of chemotherapy among the 64 patients who received it, serum GDF15 concentrations were significantly different from baseline in those who had progressive disease (P = 0.003), stable disease (P < 0.001), or partial response (P = 0.039). The AUC of GDF15 was greater than those of CEA, NSE, and CYFRA 21-1 (0.851 vs 0.630, 0.720, and 0.654, respectively). ImplicationsGDF15 is complementary to CEA, NSE, and CYFRA 21-1 in diagnosing lung cancer and, when used in combination, it could be of great diagnostic value and may facilitate correct predictions of the efficacy of chemotherapy. Therefore, serum GDF15 concentration is valuable in lung cancer diagnosis and in the evaluation of the efficacy of chemotherapy.

Expression of the Body-Weight Signaling Players: GDF15, GFRAL and RET and their clinical relevance in Gastric Cancer.

The existence, the functional role and clinical relevance of GDF15 and its signaling through a GFRAL/RET-dependent complex in gastric cancer (GC) and other human tumors remain to be elucidated, despite the widespread recognition of obesity as an important cancer-predisposing factor. Therefore, we aimed to analyze the expression levels of GDF15, GFRAL and RET in GC tissues in relation to each other and clinicopathological features, including patient survival, in order to establish a potential implication of the body-weight signaling pathway in the pathology and clinical outcome of GC. Protein expression was examined by immunohistochemistry on tissue microarrays containing 104 and 30 consecutive GC and normal gastric mucosa samples, whereas gene expression data for The Cancer Genome Atlas cohort of 413 GC patients were obtained from public sources. We found that the protein expression of GDF15, GFRAL and RET was significantly elevated and positively correlated in our set of GC tissues, which was reflected in their tendency to be overexpressed in low-grade and intermediate-grade tumors rather than high-grade ones. No other relationships between the expression status of the examined proteins and clinicopathological characteristics of GC patients were found. Through in silico data analysis, we showed that high GDF15 expression was associated with better overall survival (OS) of GC patients, whereas the opposite was true for high levels of GFRAL or RET. Specifically, GFRAL and RET emerged as independent prognostic factors associated with poor OS. Furthermore, high combined expression of the three markers: GDF15+GFRAL+RET was significantly associated with reduced OS, and it was an independent prognostic factor of borderline significance in terms of OS, when adjusted for covariates. If validated in large-scale studies, the individual and combined expression of GDF15, GFRAL and RET may provide significant clinical implications for the prognosis prediction of GC patients.

SCAP Mediated GDF15-Induced Invasion and EMT of Esophageal Cancer.

Background: GDF15 is a potential biomarker for patients with esophageal cancer (EC). However, the mechanistic role of GDF15 in the invasion and metastasis of EC remains poorly understood.Methods: We determined the expression and function of GDF15 in esophageal cancer cells (ESCCs) and in patient tissue samples using western blotting, migration, and invasion assays, immunohistochemistry, Co-IP assays, and quantitative real-time-PCR. In addition, a pulmonary metastatic nude mouse model was used to determine the function of GDF15. We then supplemented our experimental results with database analysis to validate our findings.Results: GDF15 was upregulated in EC, and was associated with poor differentiation, high metastasis rates, and worse prognosis. GDF15 knock-down reduced the migration and invasion of ESCCs. Co-IP assays demonstrated its association with SCAP, while GDF15 knock-down decreased SCAP levels. SCAP overexpression reversed the migration, invasion and EMT in GDF15-siRNA ESCCs. However, after incubation with β-cyclodextrin (β-CD), the ability of migration and invasion was weakened, EMT was reversed again. Migration, invasion, and EMT were enhanced in GDF15-siRNA ESCCs cultured in the presence of cholesterol and were similar to GDF15-siRNA ESCCs overexpressing SCAP. In vivo, knockdown of GDF15 inhibited lung metastasis of ESCCs and was reversed by SCAP overexpression or high cholesterol diet. Increased lung metastasis after SCAP overexpression was partially suppressed by intraperitoneal injection of β-CD. In addition, we determined that GDF15 was a direct target of miR-1324, miR-1324 was down-regulated in EC tissues. MiR-1324 upregulation resulted in decreased GDF15 expression and metastasis in ESCCs.Conclusions: We demonstrated that SCAP mediated GDF15-induced the invasion and metastasis of EC by regulating cholesterol metabolism. In addition, GDF15 was shown to be a direct target of miR-1324.

Abstract D114: VIitamin D signaling of immune-related genes in diverse prostate cancer cancer cell lines

Abstract BACKGROUND: African American (AA) men are disproportionately affected by both prostate cancer (PCa) and vitamin D deficiency compared with European American (EA) men. Vitamin D deficiency is linked to increased PCa aggressiveness and mortality. Inflammation also plays an important role in PCa pathogenesis and progression, and expression of immune-related in genes in PCa tissues differs significantly between AAs and EAs. While evidence linking vitamin D and immune response to PCa remains scarce, previous studies demonstrated that vitamin D has anti-inflammatory effects in prostate tissue and mediates immune-related gene expression. Therefore, we hypothesize that vitamin D deficiency in AA men may alter the expression of immune-related genes associated with prostatic inflammation and PCa progression. METHODS: This study examined the effects of vitamin Don the expression of vitamin D- and immune-related genes. Weexposed a racially diverse panel of PCa cell lines—MDA-PCa-2b (AA), RC77T/E (AA), PC3 (EA), 22Rv1 (EA), and DU145 (EA)—to various concentrations (2.5 nM, 10 nM, 50 nM) of 25-hydroxyvitamin D (25(OH)D) and 1,25 dihydroxyvitamin D (1,25(OH)2D) for 24 hours, and quantified transcript levels and protein expression of VDR, RXRa, RXRb, LRP2, CYP27B1, GDF15, GFRAL, TNFa, IL6, IL8, and IGFBP3 with qPCR and immunoblotting. RESULTS:All cell lines expressed basal levels of VDR, RXRa, and RXRbconfirming the function of vitamin D signaling within PCa cells. Of the downstream immune-related genes tested, we observed a trend demonstrating that vitamin D treatment induced the greatest upregulation in either transcript and/or protein levels among the AA PCa cell lines RC77T/E and/or MDA-PCa-2b. In particular, LRP2, GDF15, TNFa, IL6, IL8, and IGFBP3 significantly increased in AA PCa cell lines exposed to either 25(OH)D or 1,25(OH)2D. CONCLUSIONS: These findings provide insight into a potential differential regulation of immune-related pathways by vitamin D in AA men compared to EA men with PCa. Further studies are warranted to better define the immune profile in prostatic tissue in response to vitamin D deficiency in AA men, and the downstream inflammatory effects on the microenvironment and tumor aggressiveness. Citation Format: Madhavi Bathina, Leanne Woods-Burnham, Mya S Walker, K Sean Kimbro, Rick A Kittles. VIitamin D signaling of immune-related genes in diverse prostate cancer cancer cell lines [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D114.

Hypoxia Induces Growth Differentiation Factor 15 to Promote the Metastasis of Colorectal Cancer via PERK-eIF2α Signaling

Hypoxia plays an essential role in orchestrating Epithelial-mesenchymal transition and promoting metastasis of colorectal cancer. However, the underlying mechanisms are still not well elucidated. Here, we present that hypoxic exposure causes endoplasmic reticulum stress and activates the unfolded protein response pathways, which drives GDF15 expression in colorectal cancer cells. Mechanistically, upregulated CHOP led by activated PERK-eIF2α signaling promotes GDF15 transcription via directly binding to its promoter. Further study implicates that hypoxia-induced GDF15 is required for the EMT and invasion of colorectal cancer cells; enforced expression of GDF15 promotes the mitochondrial oxidation of fatty acids in colorectal cancer cells. Moreover, the abrogation of GDF15 results in smaller xenograft tumors in size and impaired metastasis. GDF15 is expressed much more in tumor tissues of CRC patients and displays positive correlations with CHOP and HIF1α in mRNA levels. Our study demonstrates a novel molecular mechanism underlying hypoxia-promoted metastasis of CRC and provides PERK signaling-regulated GDF15 as a new and promising therapeutic target for clinical treatment and drug discovery.

Circular RNA hsa-circ-0007766 modulates the progression of Gastric Carcinoma via miR-1233-3p/GDF15 axis.

Circular RNAs (circRNAs), a new kind of non-coding RNAs, have gradually been proved to be critical regulators of gene expression; however, the underlying mechanisms still need to be elaborated. In the present study, we investigated the role of hsa-circ-0007766 in gastric carcinoma (GC). Quantitative real-time PCR was applied to detect the differential expression levels of circRNA, miRNAs, and mRNAs in human tissues and specific cell lines. GC cell lines were transiently transfected with siRNA. Then the proliferation, migration, and invasion assays were performed to evaluate the effect of hsa-circ-0007766 in GC cell lines. Fluorescence in situ hybridization, RNA pulldown assay was used to confirm the location of hsa-circ-0007766 and its relationship with miR-1233-3p. Luciferase reporter assay was then conducted to verify the interaction between miR-1233-3p and GDF15. Interestingly, we found that hsa-circ-0007766 was highly expressed in human GC tissues and GC cell lines. Knock-down of hsa-circ-0007766 inhibited cell proliferation, migration, invasion, and down-regulated the expression of GDF15. Moreover, hsa-circ-0007766 was identified as a sponge of miR-1233-3p, which could target gene GDF15 to regulate the progression of GC. Finally, hsa-circ-0007766 was evaluated to be a valuable diagnostic marker with a sensitivity of 53.33% and specificity of 83.33% by ROC analysis. This study unveils a mechanism by which hsa-circ-0007766 regulates GDF15 via hsa-circ-0007766/miR-1233-3p/GDF15 axis, which may provide new insight for GC therapeutic strategies.

Senescence-associated tissue microenvironment promotes colon cancer formation through the secretory factor GDF15.

The risk of colorectal cancer (CRC) varies between people, and the cellular mechanisms mediating the differences in risk are largely unknown. Senescence has been implicated as a causative cellular mechanism for many diseases, including cancer, and may affect the risk for CRC. Senescent fibroblasts that accumulate in tissues secondary to aging and oxidative stress have been shown to promote cancer formation via a senescence‐associated secretory phenotype (SASP). In this study, we assessed the role of senescence and the SASP in CRC formation. Using primary human colon tissue, we found an accumulation of senescent fibroblasts in normal tissues from individuals with advanced adenomas or carcinomas in comparison with individuals with no polyps or CRC. In in vitro and ex vivo model systems, we induced senescence using oxidative stress in colon fibroblasts and demonstrated that the senescent fibroblasts secrete GDF15 as an essential SASP factor that promotes cell proliferation, migration, and invasion in colon adenoma and CRC cell lines as well as primary colon organoids via the MAPK and PI3K signaling pathways. In addition, we observed increased mRNA expression of GDF15 in primary normal colon tissue from people at increased risk for CRC in comparison with average risk individuals. These findings implicate the importance of a senescence‐associated tissue microenvironment and the secretory factor GDF15 in promoting CRC formation.

Identification of differentially expressed genes and preliminary validations in cardiac pathological remodeling induced by transverse aortic constriction.

Cardiac remodeling predisposes to heart failure if the burden is unresolved, and heart failure is an important cause of mortality in humans. The aim of the present study was to identify the key genes involved in cardiac pathological remodeling induced by pressure overload. Gene expression profiles of the GSE5500, GSE18224, GSE36074 and GSE56348 datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs), defined as |log2FC|>1 (FC, fold change) and an adjusted P-value of <0.05, were screened using the R software with the limma package. Gene ontology enrichment analysis was performed and a protein-protein interaction (PPI) network of the DEGs was constructed. A cardiac remodeling model induced by transverse aortic constriction (TAC) was established. Furthermore, consistent DEGs were further validated using reverse transcription-quantitative polymerase chain reaction (RT-PCR) analysis, western blotting and immunohistochemistry in the ventricular tissue samples after TAC or sham operation. A total of 24 common DEGs were identified (23 significantly upregulated and 1 downregulated), of which 9 genes had been previously confirmed to be directly involved in cardiac remodeling. Hence, the level of expression of the other 15 genes was detected in subsequent studies via RT-PCR. Based on the results of the PPI network analysis and RT-PCR, we further detected the protein levels of Itgbl1 and Asporin, which were consistent with the results of bioinformatics analysis and RT-PCR. The expression of Itgbl1, Aspn, Fstl1, Mfap5, Col8a1, Ltbp2, Mfap4, Pamr1, Cnksr1, Aqp8, Meox1, Gdf15 and Srpx was found to be upregulated in a mouse model of cardiac remodeling, while that of Retnla was downregulated. Therefore, the present study identified the key genes implicated in cardiac remodeling, aiming to provide new insight into the underlying mechanism.

Abstract 795: GDF15, the putative mitokine factor, promotes tumor progression in thyroid cancer via STAT3 regulation

Abstract Purpose: As mitochondrial dysfunction is an integral component during the initial stages of tumorigenesis, mechanistic insight on the interaction between these two pathways may lead to novel therapeutic approaches. The aim of this study is to investigate the role of GDF15, the putative mitokine factor in thyroid tumorigenesis. Methods: Expression levels of GDF15 was investigated using The Cancer Genome Atlas database. The role of GDF15 in tumor aggressiveness was investigated by analyzing the effects of knock-down of GDF15 on proliferation, migration, and invasion of thyroid cancer cells. Serum levels of GDF15 were measured in healthy subjects and patients with papillary thyroid cancer (PTC), and expression of GDF15 by IHC was investigated in PTC samples. To investigate the exact mechanism of GDF15 in thyroid cancer, both IPA analysis and GSEA analysis were performed using TCGA database and RNA seq data from Chungnam national university hospital. Results: TCGA data revealed the higher expression of GDF15 in tumor samples compared to in paired non-tumor samples. Thyroid cancer cells with knock-down of GDF15 revealed the decrease of proliferation, migration, and invasion compared to control cells via regulation of STAT3. Higher serum levels of GDF15 were found in patients with thyroid cancer than in control participants, and were significantly associated with tumor stage, lymphovascular invasion, and recurrence. In addition, patients with high GDF15 expression by IHC revealed the aggressive phenotype compared to patients with low GDF15 expression. Conclusions: GDF15 is a new biomarker for predicting tumor progression, and therapies targeting GDF15 may be effective for treating thyroid cancer. Citation Format: Yea Eun Kang, Jae Won Chang, Lihua Liu, Kyoungmin Lee, Mi Ae Lim, Seung-Nam Jung, Chan Oh, Ho-Ryun Won, Minho Shong, Bon Seok Koo. GDF15, the putative mitokine factor, promotes tumor progression in thyroid cancer via STAT3 regulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 795.

GDF15 induced apoptosis and cytotoxicity in A549 cells depends on TGFBR2 expression.

GDF15 plays a paradoxical role during carcinogenesis; it inhibits tumour growth in the early stages and promotes tumour cell proliferation in the late stages of cancer. Besides, GDF15 can induce apoptosis in some cancer cells including A549 but not in some others. Moreover, as a potential receptor for GDF15, TGFBR2 is inactivated during carcinogenesis in many types of cancers, and it is not present in cells with no GDF15 induced apoptosis. Thus, we tested whether GDF15 overexpression and/or TGFBR2 silencing can affect the GDF15 induced apoptosis in A549 cells. The full and mature forms of GDF15 were cloned and overexpressed in A549 cells. The TGFBR2 was silenced using specific siRNA and confirmed by real-time PCR. Results indicated that overexpression of full and mature forms of GDF15 as well as TGFBR2 knocked down reduced A549 cell viability in 24 and 48hours. Flow cytometric analysis of annexin V/PI indicated induction of apoptosis in A549 cells by overexpression of GDF15 or silencing TGFBR2. Interestingly, the silencing of TGFBR2 inhibited the GDF15 induced cytotoxicity and apoptosis in A549 cells. Overexpression of GDF15 activated caspase-9 and caspase-3 and inhibited ERK1/2 and p38 phosphorylation in A549 cells. TGFBR2 knocked down inhibited GDF15 effects on caspases, ERK1/2, and p38MAPK activation. Our results indicated that the effect of GDF15 on apoptosis and activation of MAPK in A549 cells depends on TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression. SIGNIFICANCE OF THE STUDY: GDF15 plays a tumour suppressor or promotor roles during carcinogenesis. The expression of GDF15 induced cytotoxicity, apoptosis, and inhibition of MAPK in A549 cells. All these effects were blocked by silencing TGFBR2 expression. These findings may point to mechanisms in which GDF15 exerts dual effect during carcinogenesis with regard to TGFBR2 expression.

Prospects of the Application of Buccal Epithelium for Noninvasive Diagnosis of Coronary Heart Disease in People of Different Ages

Cardiovascular diseases caused by atherosclerosis are one of the most important social and economic problems in many countries of the world due to the high morbidity and mortality rate of the working population. An immunological theory of atherosclerosis and coronary heart disease (CHD) has been actively developed of late, and markers of inflammation characterizing immuno- and atherogenesis have been sought. The buccal epithelium (BE) can be used as biological material for in vivo molecular-cellular studies, allowing CHD diagnosis via inflammation markers. The purpose of the work was a comparative study of the expression of IL-1β, IL-6, IL-10, MCP-1, and GDF-15 in BE in patients of different ages with CHD and without cardiovascular disease. The BE material in healthy donors and patients with second-stage CHD was divided into groups according to the age classification of the WHO: the first group included middle-aged people (45–59 years), and the second included elderly people (60–74 years). Control material was obtained from people of middle and old age without cardiovascular disease. According to the immunocytochemical study, the area of IL-1β expression in BE is three times higher in middle-aged CHD patients and 4.4 times higher in elderly people as compared to healthy individuals of the same age group. The area of IL-6 expression in middle-aged and elderly CHD patients was 7.9 and 7.4 times higher, respectively, than in the control group. In middle-aged and elderly CHD patients, the IL-10 expression was 1.6 and 2.8 times higher, respectively, as compared to healthy donors of the same age group. The MCP-1 expression in the BE of middle-aged and elderly people with and without ischemic heart disease did not differ. GDF-15 expression is 6.8 and 6.6 times higher in middle-aged and elderly CHD patients than in healthy people of the same age. The findings showed that the expression of the cytokines IL-1β, IL-6, IL-10, and GDF-15 increase in the BE of patients with CHD in middle-aged and elderly people as compared with persons of the same age group without cardiovascular disease. Thus, the BE can serve as an informative material for noninvasive molecular diagnosis of CHD in people of different ages.