Discoidin Domain Receptor 2 Signaling Research Articles

Functional Role of DDR1 in Oligodendrocyte Signaling Mechanism in Association with Myelination and Remyelination Process in the Central Nerve System.

Multiple sclerosis (MS) is a complicated, inflammatory disease that causes demyelination of the central nervous system (CNS), resulting in a variety of neurological abnormalities. Over the past several decades, different animal models have been used to replicate the clinical symptoms and neuropathology of MS. The experimental model of experimental autoimmune/allergic encephalomyelitis (EAE) and viral and toxin-induced model was widely used to investigate the clinical implications of MS. Discoidin domain receptor 1 (DDR1) signaling in oligodendrocytes (OL) brings a new dimension to our understanding of MS pathophysiology. DDR1 is effectively involved in the OL during neurodevelopment and remyelination. It has been linked to many cellular processes, including migration, invasion, proliferation, differentiation, and adhesion. However, the exact functional involvement of DDR1 in developing OL and myelinogenesis in the CNS remains undefined. In this review, we critically evaluate the current literature on DDR1 signaling in OL and its proliferation, migration, differentiation, and myelination mechanism in OL in association with the progression of MS. It increases our knowledge of DDR1 in OL as a novel target molecule for oligodendrocyte-associated diseases in the CNS, including MS.

DDR2 signaling and mechanosensing orchestrate neuroblastoma cell fate through different transcriptome mechanisms.

The extracellular matrix (ECM) regulates carcinogenesis by interacting with cancer cells via cell surface receptors. Discoidin Domain Receptor 2 (DDR2) is a collagen-activated receptor implicated in cell survival, growth, and differentiation. Dysregulated DDR2 expression has been identified in various cancer types, making it as a promising therapeutic target. Additionally, cancer cells exhibit mechanosensing abilities, detecting changes in ECM stiffness, which is particularly important for carcinogenesis given the observed ECM stiffening in numerous cancer types. Despite these, whether collagen-activated DDR2 signaling and ECM stiffness-induced mechanosensing exert similar effects on cancer cell behavior and whether they operate through analogous mechanisms remain elusive. To address these questions, we performed bulk RNA sequencing (RNA-seq) on human SH-SY5Y neuroblastoma cells cultured on collagen-coated substrates. Our results show that DDR2 downregulation induces significant changes in the cell transcriptome, with changes in expression of 15% of the genome, specifically affecting the genes associated with cell division and differentiation. We validated the RNA-seq results by showing that DDR2 knockdown redirects the cell fate from proliferation to senescence. Like DDR2 knockdown, increasing substrate stiffness diminishes cell proliferation. Surprisingly, RNA-seq indicates that substrate stiffness has no detectable effect on the transcriptome. Furthermore, DDR2 knockdown influences cellular responses to substrate stiffness changes, highlighting a crosstalk between these two ECM-induced signaling pathways. Based on our results, we propose that the ECM could activate DDR2 signaling and mechanosensing in cancer cells to orchestrate their cell fate through distinct mechanisms, with or without involving gene expression, thus providing novel mechanistic insights into cancer progression.

Discoidin domain receptor 2 signaling through PIK3C2α in fibroblasts promotes lung fibrosis.

Pulmonary fibrosis, especially idiopathic pulmonary fibrosis (IPF), portends significant morbidity and mortality, and current therapeutic options are suboptimal. We have previously shown that type I collagen signaling through discoidin domain receptor 2 (DDR2), a receptor tyrosine kinase expressed by fibroblasts, is critical for the regulation of fibroblast apoptosis and progressive fibrosis. However, the downstream signaling pathways for DDR2 remain poorly defined and could also be attractive potential targets for therapy. A recent phosphoproteomic approach indicated that PIK3C2α, a poorly studied member of the PI3 kinase family, could be a downstream mediator of DDR2 signaling. We hypothesized that collagen I/DDR2 signaling through PIK3C2α regulates fibroblast activity during progressive fibrosis. To test this hypothesis, we found that primary murine fibroblasts and IPF-derived fibroblasts stimulated with endogenous or exogenous type I collagen led to the formation of a DDR2/PIK3C2α complex, resulting in phosphorylation of PIK3C2α. Fibroblasts treated with an inhibitor of PIK3C2α or with deletion of PIK3C2α had fewer markers of activation after stimulation with TGFβ and more apoptosis after stimulation with a Fas-activating antibody. Finally, mice with fibroblast-specific deletion of PIK3C2α had less fibrosis after bleomycin treatment than did littermate control mice with intact expression of PIK3Cα. Collectively, these data support the notion that collagen/DDR2/PIK3C2α signaling is critical for fibroblast function during progressive fibrosis, making this pathway a potential target for antifibrotic therapy. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Inhibition of discoidin domain receptor 2 reveals kinase-dependent and kinase-independent functions in regulating fibroblast activity.

Progressive pulmonary fibrosis is a devastating condition and current treatment is suboptimal. There has been considerable interest in the role of tyrosine kinase signaling as mediators of pro- and antifibrotic processes. Nintedanib is a nonspecific tyrosine kinase that has been shown to have therapeutic benefit in lung fibrosis. However, the precise mechanism of action remains unclear because nintedanib inhibits several tyrosine kinases, which are often expressed on multiple cell types with different activities during fibrosis. Discoidin domain receptor 2 (DDR2) has been suggested as a potential target of nintedanib. DDR2 is a receptor tyrosine kinase that is activated by fibrillar collagens such as type I collagen. DDR2 is primarily expressed by fibroblasts. The effectiveness of specifically targeting DDR2 signaling during fibrosis remains undefined. In the present study, we show that nintedanib acts as a direct and indirect inhibitor of DDR2. We then utilize a novel allosteric inhibitor of DDR2, WRG-28, which blocks ligand binding and activation of DDR2. We find that WRG-28 augments fibroblast apoptosis and attenuates fibrosis. Finally, we show that fibroblast type I collagen autocrine signaling is regulated by DDR2 through both kinase-dependent and kinase-independent functions of DDR2. These findings highlight the importance of type I collagen autocrine signaling by fibroblasts during fibrosis and demonstrate that DDR2 has a central role in this pathway making it a potential therapeutic target.NEW & NOTEWORTHY Type I collagen is a major component of fibrosis and can signal through cell surface receptors such as discoidin domain receptor 2 (DDR2). DDR2 activation can lead to further collagen deposition by fibroblasts setting up a profibrotic positive feedback loop. In this report, we find that inhibition of DDR2 with nintedanib or a specific DDR2 inhibitor, WRG-28, can disrupt this cycle and prevent fibrosis through augmented fibroblast apoptosis and inhibited activation.

The influence of discoidin domain receptor 1 expression on angiogenic factors: VEGF-A and FGF-2 in non-small cell lung cancer

ObjectivesLung cancer is responsible for more cancer-related death worldwide. Most lung cancer patients have non-small cell lung cancers (NSCLC), with a low survival rate. Therefore, it is necessary to study new and effective targeted therapies. Discoidin domain receptor 1 (DDR1) is a tyrosine kinase receptor that can be promoted by collagen type I, and dysregulation of DDR1 signaling is involved in several phases of tumorigenesis. Tumor growth and metastasis depend on angiogenesis caused by angiogenic factors, such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) secreted by tumor cells. Thus, angiogenesis plays a critical role in cancer progression. The current study amid to evaluate the expression alteration of DDR1 and its effects on angiogenic factors VEGF-A, FGF-1, and FGF2 in NSCLC. Materials and methodsA549 and Calu-3 cells were treated with collagen type I and transfected with DDR1 small interfering RNA (siRNA). Then, the relative expression of DDR1, VEGF-A, FGF-1, and FGF-2 of cells was evaluated using quantitative real-time polymerase chain reaction (qRT-PCR). The concentration of angiogenic factors was calculated by the Human Angiogenesis 17-plex discovery assay. ResultsAccording to our data, collagen type I could stimulate DDR1 expression in A549 and Calu-3 cells, and DDR1 upregulation resulted in a significant increase of VEGF-A and FGF-2 expression, but did not induce FGF-1 expression. Moreover, suppression of DDR1 expression could significantly decrease VEGF-A and FGF-2 expression. Conclusionour findings suggest that alteration of DDR1 expression mediated by collagen I and siRNA may affect VEGF-A and FGF-2 expression in non-small cell lung cancer associated with tumor angiogenesis and represent a new treatment approach.

Discoidin domain receptor 2 regulates aberrant mesenchymal lineage cell fate and matrix organization.

Extracellular matrix (ECM) interactions regulate both the cell transcriptome and proteome, thereby determining cell fate. Traumatic heterotopic ossification (HO) is a disorder characterized by aberrant mesenchymal lineage (MLin) cell differentiation, forming bone within soft tissues of the musculoskeletal system following traumatic injury. Recent work has shown that HO is influenced by ECM-MLin cell receptor signaling, but how ECM binding affects cellular outcomes remains unclear. Using time course transcriptomic and proteomic analyses, we identified discoidin domain receptor 2 (DDR2), a cell surface receptor for fibrillar collagen, as a key MLin cell regulator in HO formation. Inhibition of DDR2 signaling, through either constitutive or conditional Ddr2 deletion or pharmaceutical inhibition, reduced HO formation in mice. Mechanistically, DDR2 perturbation alters focal adhesion orientation and subsequent matrix organization, modulating Focal Adhesion Kinase (FAK) and Yes1 Associated Transcriptional Regulator and WW Domain Containing Transcription Regulator 1 (YAP/TAZ)-mediated MLin cell signaling. Hence, ECM-DDR2 interactions are critical in driving HO and could serve as a previously unknown therapeutic target for treating this disease process.

A network map of discoidin domain receptor 1(DDR1)-mediated signaling in pathological conditions.

Discoidin domain receptor 1 (DDR1) is one of the receptors that belong to a family of non-integrin collagen receptors. In common, DDR1 is predominantly found in epithelial and smooth muscle cells and its mainly involved in organogenesis during embryonic development. However, it's also overexpressed in several pathological conditions, including cancer and inflammation. The DDR1 is reported in numerous cancers, including breast, prostate, pancreatic, bladder, lung, liver, pituitary, colorectal, skin, gastric, glioblastoma, and inflammation. DDR1 activates through the collagen I, IV, IGF-1/IGF1R, and IGF2/IR, regulating downstream signaling molecules such as MAPKs, PI3K/Akt, and NF-kB in diseases. Despite its biomedical importance, there is a lack of consolidated network map of the DDR1 signaling pathway, which prompted us for curation of literature data pertaining to the DDR1 system following the NetPath criteria. We present here the compiled pathway map comprises 39 activation/inhibition events, 17 catalysis events, 22 molecular associations, 65 gene regulation events, 35 types of protein expression, and two protein translocation events. The detailed DDR1 signaling pathway map is made freely accessible through the WikiPathways Database ( https://www.wikipathways.org/index.php/ Pathway: https://www.wikipathways.org/index.php/Pathway:WP5288 ).

Stiffness-responsive feedback autoregulation of DDR1 expression is mediated by a DDR1-YAP/TAZ axis

Objective: Increased matrix stiffness is sensed by the collagen-binding receptor tyrosine kinase discoidin domain receptor 1 (DDR1). We have previously shown that DDR1 stimulates a positive feedback loop to increase its own expression in vascular smooth muscle cells (VSMCs). The transcriptional co-factors YAP/TAZ are stiffness sensing molecules that have not previously been investigated in DDR1 signaling. Here, we test the hypothesis that DDR1 signals through YAP/TAZ to auto-regulate its own expression.Approach and Results: We used vascular smooth muscle cells (VSMCs) from wild-type and DDR1 knockout mice stimulated with collagen and/or substrates of different stiffness. We show that DDR1 controls YAP/TAZ nuclear localization and activity, whereas knockdown of YAP/TAZ attenuates DDR1 expression. In response to increased substrate stiffness, collagen stimulation, or RhoA activation, YAP/TAZ translocate to the nucleus and bind to chromatin. Finally, collagen stimulation promotes increased YAP/TAZ association with the Ddr1 promoter.Conclusions: These findings reveal the mechanism by which DDR1 regulates YAP/TAZ activity which can then mediate positive feedback regulation of DDR1 expression by promoting transcription of the DDR1 gene.

DDR1 promotes hepatocellular carcinoma metastasis through recruiting PSD4 to ARF6

Discoidin domain receptor 1 (DDR1) is a member of the receptor tyrosine kinase family, and its ligand is collagen. Previous studies demonstrated that DDR1 is highly expressed in many tumors. However, its role in hepatocellular carcinoma (HCC) remains obscure. In this study, we found that DDR1 was upregulated in HCC tissues, and the expression of DDR1 in TNM stage II-IV was higher than that in TNM stage I in HCC tissues, and high DDR1 expression was associated with poor prognosis. Gene expression analysis showed that DDR1 target genes were functionally involved in HCC metastasis. DDR1 positively regulated the migration and invasion of HCC cells and promoted lung metastasis. Human Phospho-Kinase Array showed that DDR1 activated ERK/MAPK signaling pathway. Mechanically, DDR1 interacted with ARF6 and activated ARF6 through recruiting PSD4. The kinase activity of DDR1 was required for ARF6 activation and its role in metastasis. High expression of PSD4 was associated with poor prognosis in HCC. In summary, our findings indicate that DDR1 promotes HCC metastasis through collagen induced DDR1 signaling mediated PSD4/ARF6 signaling, suggesting that DDR1 and ARF6 may serve as novel prognostic biomarkers and therapeutic targets for metastatic HCC.

Targeting Discoidin Domain Receptor 1 (DDR1) Signaling and Its Crosstalk with β1-integrin Emerges as a Key Factor for Breast Cancer Chemosensitization upon Collagen Type 1 Binding.

Collagen type 1 (COL1) is a ubiquitously existing extracellular matrix protein whose high density in breast tissue favors metastasis and chemoresistance. COL1-binding of MDA-MB-231 and MCF-7 breast cancer cells is mainly dependent on β1-integrins (ITGB1). Here, we elucidate the signaling of chemoresistance in both cell lines and their ITGB1-knockdown mutants and elucidated MAPK pathway to be strongly upregulated upon COL1 binding. Notably, Discoidin Domain Receptor 1 (DDR1) was identified as another important COL1-sensor, which is permanently active but takes over the role of COL1-receptor maintaining MAPK activation in ITGB1-knockdown cells. Consequently, inhibition of DDR1 and ERK1/2 act synergistically, and sensitize the cells for cytostatic treatments using mitoxantrone, or doxorubicin, which was associated with an impaired ABCG2 drug efflux transporter activity. These data favor DDR1 as a promising target for cancer cell sensitization, most likely in combination with MAPK pathway inhibitors to circumvent COL1 induced transporter resistance axis. Since ITGB1-knockdown also induces upregulation of pEGFR in MDA-MB-231 cells, inhibitory approaches including EGFR inhibitors, such as gefitinib appear promising for pharmacological interference. These findings provide evidence for the highly dynamic adaptation of breast cancer cells in maintaining matrix binding to circumvent cytotoxicity and highlight DDR1 signaling as a target for sensitization approaches.

The Role of Discoidin Domain Receptor 2 in Tooth Development

Collagen signaling is critical for proper bone and tooth formation. Discoidin domain receptor 2 (DDR2) is a collagen-activated tyrosine kinase receptor shown to be essential for skeletal development. Patients with loss of function mutations in DDR2 develop spondylo-meta-epiphyseal dysplasia (SMED), a rare, autosomal recessive disorder characterized by short stature, short limbs, and craniofacial anomalies. A similar phenotype was observed in Ddr2-deficient mice, which exhibit dwarfism and defective bone formation in the axial, appendicular, and cranial skeletons. However, it is not known if Ddr2 has a role in tooth formation. We first defined the expression pattern of Ddr2 during tooth formation using Ddr2-LacZ knock-in mice. Ddr2 expression was detected in the dental follicle/sac and dental papilla mesenchyme of developing teeth and in odontoblasts and the periodontal ligament (PDL) of adults. No LacZ staining was detected in wild-type littermates. This Ddr2 expression pattern suggests a potential role in the tooth and surrounding periodontium. To uncover the function of Ddr2, we used Ddr2 slie/slie mice, which contain a spontaneous 150-kb deletion in the Ddr2 locus to produce an effective null. In comparison with wild-type littermates, Ddr2 slie/slie mice displayed disproportional tooth size (decreased root/crown ratio), delayed tooth root development, widened PDL space, and interradicular alveolar bone defects. Ddr2 slie/slie mice also had abnormal collagen content associated with upregulation of periostin levels within the PDL. The delayed root formation and periodontal abnormalities may be related to defects in RUNX2-dependent differentiation of odontoblasts and osteoblasts; RUNX2-S319-P was reduced in PDLs from Ddr2 slie/slie mice, and deletion of Ddr2 in primary cell cultures from dental pulp and PDL inhibited differentiation of cells to odontoblasts or osteoblasts, respectively. Together, our studies demonstrate odontoblast- and PDL-specific expression of Ddr2 in mature and immature teeth, as well as indicate that DDR2 signaling is important for normal tooth formation and maintenance of the surrounding periodontium.

2-Amino-2,3-dihydro-1H-indene-5-carboxamide-Based Discoidin Domain Receptor 1 (DDR1) Inhibitors: Design, Synthesis, and in Vivo Antipancreatic Cancer Efficacy.

A series of 2-amino-2,3-dihydro-1H-indene-5-carboxamides were designed and synthesized as new selective discoidin domain receptor 1 (DDR1) inhibitors. One of the representative compounds, 7f, bound with DDR1 with a Kd value of 5.9 nM and suppressed the kinase activity with an half-maximal (50%) inhibitory concentration value of 14.9 nM. 7f potently inhibited collagen-induced DDR1 signaling and epithelial–mesenchymal transition, dose-dependently suppressed colony formation of pancreatic cancer cells, and exhibited promising in vivo therapeutic efficacy in orthotopic mouse models of pancreatic cancer.

Epithelial polarization in 3D matrix requires DDR1 signaling to regulate actomyosin contractility.

Epithelial cells form sheets and tubules in various epithelial organs and establish apicobasal polarity and asymmetric vesicle transport to provide functionality in these structures. However, the molecular mechanisms that allow epithelial cells to establish polarity are not clearly understood. Here, we present evidence that the kinase activity of the receptor tyrosine kinase for collagen, discoidin domain receptor 1 (DDR1), is required for efficient establishment of epithelial polarity, proper asymmetric protein secretion, and execution of morphogenic programs. Lack of DDR1 protein or inhibition of DDR1 kinase activity disturbed tubulogenesis, cystogenesis, and the establishment of epithelial polarity and caused defects in the polarized localization of membrane-type 1 matrix metalloproteinase (MT1-MMP), GP135, primary cilia, laminin, and the Golgi apparatus. Disturbed epithelial polarity and cystogenesis upon DDR1 inhibition was caused by excess ROCK (rho-associated, coiled-coil-containing protein kinase)-driven actomyosin contractility, and pharmacological inhibition of ROCK was sufficient to correct these defects. Our data indicate that a DDR1-ROCK signaling axis is essential for the efficient establishment of epithelial polarity.

N terminal-DDR1, A serum prognostic marker for liver fibrosis

Introduction: Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that binds and transmits signals from various collagens in epithelial cells, which including liver cells. However, how DDR1-dependent signaling is regulated has not been understood. It was report that collagen binding induces ectodomain shedding of DDR1. As we know, organ fibrosis is highly dependent on collagens aggregation in target organ. But, no one reported the relationship between DDR1 shedding and liver fibrosis. Methods: Here, we valuated the N-Terminal DDR1 in cell culture suspension, which treated by collagen I. We also contributed DDR1 shedding in (Bible- Duct Ligation) BDL mouse model, CCL4 induced liver fibrosis mouse model, HBV related liver fibrosis mouse model, and checked the serum N-terminal DDR1 by Elisa Assay. Furthermore, clinical blood specimens from patients with different stage of liver fibrosis were measured by DDR1-N terminal antibody using Elisa Assay. Results: We found that shedding is not a result of DDR1 signaling, but it results from collagen binding to the ecto- domain of DDR1. More collagen added in culture cell, more N-terminal DDR1 could be detected in suspension. The worse fibrosis of liver in all three mouse models, the more DDR1 shedding was diagnosed. Furthermore, the worse fibrosis of patients, the more N- teminal DDR1 was checked out in their serum. Conclusion: In this report, we identified DDR1 shedding could secret N-teminal DDR1 in serum, which is induced by collagen binding. N- teminal DDR1 was supposed to be a diagnostic hall marker of liver fibrosis.

Inhibition of EP300 and DDR1 synergistically alleviates pulmonary fibrosis in vitro and in vivo

ObjectivesPulmonary fibrosis is strongly correlated with inflammation factors, cytokine, and collagen secretion, whereby discoidin domain receptor 1 (DDR1) signaling plays an important role. EP300 is defined as an acetyltransferase that can acetylate histone and has been broadly studied in several chronic diseases, including cancer, inflammation and fibrosis. This study aimed to investigate the relationship between p300 and DDR1 in the pathological processes of pulmonary fibrosis. Materials and methodsTranscriptome analysis of single cell RNA-sequencing for idiopathic pulmonary fibrosis (IPF) bronchial epithelial cells demonstrated that both DDR1 and EP300 were up-regulated and involved in the regulation of autophagy, cellular response to organonitrogen compounds, and collagen metabolic pathways, respectively. The anti-fibrotic and anti-inflammation effects of Pim1 and DDR1 inhibitors in bleomycin-induced IPF murine models were estimated. ResultsWe discovered that overexpression of EP300 signaling induced MRC5 human fibroblast cells that up-regulated the expression of DDR1 and FN1; however, no effects on COL1 A1 and DDR1 phosphorylation were observed. Mechanistically, TGF-β1 activated FN1, collagen, and DDR1 signaling could be reversed by the combination of p300 siRNA and DDR1 inhibitors. Moreover, the EP300 inhibitor SGC-CBP30 displayed synergistic effects with DDR1 inhibitors in pathogenic scores, airway goblet cell counts in bronchoalveolar lavage fluid (BALF), IL-4, IFN-γ, FN1COL1 A1 secretion and α-SMA, a marker of myofibroblast. ConclusionsThe EP300 siRNA and inhibitors sensitized DDR1 inhibitors in our pulmonary fibrosis models in vitro and in vivo, implicating a combined inhibition of DDR1 with EP300 as potential therapies for IPF.

Inhibition of tumor–microenvironment interaction and tumor invasion by small-molecule allosteric inhibitor of DDR2 extracellular domain

The action of the collagen binding receptor tyrosine kinase (RTK) discoidin domain receptor 2 (DDR2) in both tumor and tumor stromal cells has been established as critical for breast cancer metastasis. Small molecule inhibitors that target the extracellular domain of RTKs are rare, as they have classically been regarded as too small to block binding with large polypeptide ligands. Here, we report the identification and characterization of a selective, extracellularly acting small molecule inhibitor (WRG-28) of DDR2 that uniquely inhibits receptor-ligand interactions via allosteric modulation of the receptor. By targeting DDR2, WRG-28 inhibits tumor invasion and migration, as well as tumor-supporting roles of the stroma, and inhibits metastatic breast tumor cell colonization in the lungs. These findings represent an approach to inhibiting tumor-stromal interactions and support the development of allosteric inhibitors of DDR2, such as WRG-28, as a promising approach to antimetastasis treatment.

Abstract A036: DDR2 expression is associated with poor prognosis in head and neck squamous cell carcinoma

Abstract Head and neck squamous cell carcinoma (HNSCC) is a malignant tumor of epithelial keratinocytes that represents a growing public health problem. It is one of the most common solid cancers worldwide with rate of 9.2/100,000 people. In 2016, the estimate in Brazil is 6.3/100,000 men and 3.4/100,000 women. The prognosis is poor, especially once it recurs or metastasizes. Current therapeutic options include surgery, radio- and/or chemotherapy. Targeted therapy holds great promise of improving patient outcome while limiting toxicity and treatment exposure. Understanding the molecular cancer pathways of underlying HNSCC metastasis would help to improve the therapy of the disease. Discoidin domain receptor 2 (DDR2) is a receptor tyrosine kinase (RTK) that can be activated by fibrillar collagens and implicated in several cancer cell behaviors, including VEGF expression, tumor angiogenesis, invasion, and metastasis. Matrix metalloproteinases (MMPs) are an important subset of downstream target genes of DDR2 signaling. Though previous studies have investigated the function of DDR2 in some common tumors, there has not been functional characterization of the potential role of DDR2 in HNSCC. Therefore, the aim of the current study was to investigate this issue. The general objective of this project is to verify the potential DDR2 gene as tumor markers and therapeutic target in HNSCC. In this study, DDR2 expression was examined by immunohistochemistry in 50 HNSCC patients, and the correlation between DDR2 expression with clinicopathologic factors was analyzed. The result showed DDR2 expression in all the nucleus, cytoplasm, and membrane in HNSCC patients. Statistical analysis revealed that DDR2 expression is associated with overall survival and recurrent-free survival. Patients with high DDR2 expression in the nucleus showed 6-fold higher risk of death compared to patients with a low level of DDR2 expression (p = 0,003) and 40-fold more chance of recurrence (p = 0,001). High DDR2 expression in the cytoplasm showed a 2.2-fold higher risk of death compared to patients with a low level (p = 0,026) and 47-fold more chance of recurrence (p = 0,006). In relation to plasma membrane, high DDR2 expression the results showed a 3.8-fold higher risk of death compared to patients with a low level (p = 0,008) and 6.5-fold more chance of recurrence (p = 0,009). In conclusion, these data suggest that DDR2 expression may be a prognostic indicator and a useful therapeutic target. Citation Format: Flavia Amoroso Matos e Silva, Katia Klug, Claudia Malheiros Coutinho-Camillo, Luiz Paulo Kowalski, Fernando Augusto Soares. DDR2 expression is associated with poor prognosis in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A036.

Inhibition of Discoidin Domain Receptor 1 Reduces Collagen-mediated Tumorigenicity in Pancreatic Ductal Adenocarcinoma.

The extracellular matrix (ECM), a principal component of pancreatic ductal adenocarcinoma (PDA), is rich in fibrillar collagens that facilitate tumor cell survival and chemoresistance. Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase that specifically binds fibrillar collagens and has been implicated in promoting cell proliferation, migration, adhesion, ECM remodeling, and response to growth factors. We found that collagen-induced activation of DDR1 stimulated protumorigenic signaling through protein tyrosine kinase 2 (PYK2) and pseudopodium-enriched atypical kinase 1 (PEAK1) in pancreatic cancer cells. Pharmacologic inhibition of DDR1 with an ATP-competitive orally available small-molecule kinase inhibitor (7rh) abrogated collagen-induced DDR1 signaling in pancreatic tumor cells and consequently reduced colony formation and migration. Furthermore, the inhibition of DDR1 with 7rh showed striking efficacy in combination with chemotherapy in orthotopic xenografts and autochthonous pancreatic tumors where it significantly reduced DDR1 activation and downstream signaling, reduced primary tumor burden, and improved chemoresponse. These data demonstrate that targeting collagen signaling in conjunction with conventional cytotoxic chemotherapy has the potential to improve outcome for pancreatic cancer patients. Mol Cancer Ther; 16(11); 2473-85. ©2017 AACR.

Abstract LB-216: Stroma-induced up-regulation of discoidin domain receptor 1 enhances peritoneal metastasis of gastric carcinomas

Abstract Introduction: Discoidin domain receptor-1 (DDR1), a receptor tyrosine kinase, is expressed by about 50% of gastric tumor cells in previous our study and is activated by fibrillar collagens, which are major components of tumor stroma. Further, it has been proposed that peritoneal metastasis is associated with high stroma content in gastric carcinomas (GCs). In this study we investigated the contribution of DDR1 activity to peritoneal metastasis of GCs. Methods: We performed the immunohistochemistry for DDR1 and Masson’s trichrome staining for accumulation of collagen bundles in 202 human GC tissues. The human GC cell lines (MKN-28 and KATO-III) were co-cultured with GCs-associated fibroblasts (CAFs), and the expression of DDR1 and signal transduction pathways were investigated by Western blot. We evaluated CAF-induced tumorigenesis of GCs cell lines and the effects of DDR1 specific inhibitor in 3D co-culture system and peritoneal seeding in xenograft animal models. Results: High stromal collagen correlated with peritoneal recurrence (P=0.004) and was positively associated with expression of DDR1 in GC tissues (P<0.001). We confirmed that co-culture with CAFs elevated the expression of DDR1 in GC cell lines. CAFs also enhanced GC cell line spheroid formation in vitro in a tumor cell DDR1-dependent manner. Co-implantation of CAFs with GC cells enhanced peritoneal tumor formation in vivo, an effect that was sensitive to pharmacologic inhibition of DDR1. Conclusion: Our findings suggest that CAF-induced elevation of tumor cells DDR1 enhances peritoneal tumorigenesis of GCs and the inhibition of DDR1 signaling is an attractive strategy for the treatment of GC peritoneal metastasis. Citation Format: Hyejin Jin, In-Hye Ham, Hye Jung Oh, Dakeun Lee, Sang-Uk Han, Rolf A. Brekken, Hoon Hur. Stroma-induced up-regulation of discoidin domain receptor 1 enhances peritoneal metastasis of gastric carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-216. doi:10.1158/1538-7445.AM2017-LB-216

Mesenchymal Stem Cell-Induced DDR2 Mediates Stromal-Breast Cancer Interactions and Metastasis Growth

Increased collagen deposition by breast cancer (BC)-associated mesenchymal stem/multipotent stromal cells (MSC) promotes metastasis, but the mechanisms are unknown. Here, we report that thecollagen receptor discoidin domain receptor 2 (DDR2) is essential for stromal-BC communication. In human BC metastasis, DDR2 is concordantly upregulated in metastatic cancer and multipotent mesenchymal stromal cells. In MSCs isolated from human BC metastasis, DDR2 maintains a fibroblastic phenotype with collagen deposition and induces pathological activation of DDR2 signaling in BC cells. Loss of DDR2 in MSCs impairs their ability to promote DDR2 phosphorylation in BC cells, as well as BC cell alignment, migration, and metastasis. Female ddr2-deficient mice homozygous for the slie mutation show inefficient spontaneous BC metastasis. These results point to a role for mesenchymal stem cell DDR2 in metastasis and suggest a therapeutic approach for metastatic BC.