Discoidin Domain Receptor Research Articles

Adipose-derived stem cells-derived exosomes facilitate cutaneous wound healing by delivering XIST and restoring discoidin domain receptor 2

BackgroundAdipose-derived stem cells (ADSCs) and their derived exosomes (ADSC-Exos) have shown potential functions in tissue repair. This study focuses on the effects of ADSCs-Exos on cutaneous wound healing and the potential involvement of the long non-coding RNA (lncRNA) XIST/microRNA-96-5p (miR-96-5p)/discoidin domain receptor 2 (DDR2) axis. MethodsExos were isolated from the ADSCs and identified. A mouse model of full-thickness skin wounds was established. The mice were treated with ADSC-Exos to evaluate the function of ADSC-Exos in wound healing. Mouse dermal fibroblasts (MDFs) were co-cultured with the ADSC-Exos for in vitro experiments. The most differentially expressed lncRNAs in mouse skin tissues after ADSC-Exo treatment were screened by microarray analysis. The downstream molecules were analyzed by bioinformatics tools. Gain- and loss-of-function studies were performed to examine the functions of the XIST/miR-96-5p/DDR2 axis in wound healing. ResultsADSC-Exos facilitated wound healing in mice, reduced inflammatory infiltration, and increased collagen deposition in the wound skin tissues. In vitro, the ADSC-Exos promoted proliferation, migration of the MDFs. XIST was the most upregulated lncRNA in MDFs after ADSC-Exo treatment. Downregulation of XIST suppressed the promoting role of ADSC-Exos in wound healing. XIST bound to miR-96-5p to restore the expression of DDR2 mRNA. Either silencing of miR-96-5p or overexpression of DDR2 restored the promoting functions of ADSC-Exos in proliferation and migration of MDFs. ConclusionThis study demonstrates that ADSC-Exos-carried XIST accelerates cutaneous wound healing through suppressing miR-96-5p and restoring the DDR2 expression.

Deficiency in DDR1 Induces Pulmonary Hypertension and Impaired Alveolar Development.

Pulmonary hypertension (PH) is a multifaceted condition characterized by elevated pulmonary arterial pressure, which can result in right ventricular dysfunction and failure. Disorders of lung development can present with secondary PH, which is a leading cause of mortality in infants with bronchopulmonary dysplasia (BPD). DDR1 (discoidin domain receptor 1) is a collagen-binding receptor that regulates tissue fibrosis and inflammation and controls cellular growth and migration. However, the roles of DDR1 in lung development or the pathogenesis of PH are unknown. Studying mice with a DDR1 deletion (Ddr1-/-), we have noted 35% mortality between 1 and 4 months of age, and we demonstrate that DDR1 deficiency results in reduced right ventricular contractility and muscularization of distal pulmonary arteries, consistent with PH. Pathology analysis revealed enlarged alveolar spaces in Ddr1-/- mice by Postnatal Day 7, consistent with impaired alveolar development. Gene expression analysis showed that Ddr1-/- mice have reduced concentrations of alveologenesis factors and epithelial-to-mesenchymal transition markers. Mechanistic studies invitro confirmed that DDR1 mediated epithelial-to-mesenchymal transition, migration, and growth of alveolar epithelial cells. Taken together, these data suggest that DDR1 plays important roles mediating alveolarization during lung development. Our studies also describe a new model of spontaneous PH and bronchopulmonary dysplasia in mice.

Discoidin Domain Receptor-Driven Gene Signatures as Markers of Patient Response to Anti-PD-L1 Immune Checkpoint Therapy.

Anti-programmed cell death 1 (anti-PD-1) and PD ligand 1 (PD-L1) immune checkpoint therapies (ICTs) provided durable responses only in a subset of cancer patients. Thus, biomarkers are needed to predict nonresponders and offer them alternative treatments. We recently implicated discoidin domain receptor tyrosine kinase 2 (DDR2) as a contributor to anti-PD-1 resistance in animal models; therefore, we sought to investigate whether this gene family may provide ICT response prediction. We assessed mRNA expression of DDR2 and its family member DDR1. Transcriptome analysis of bladder cancer (BCa) models in which DDR1 and 2 were perturbed was used to derive DDR1- and DDR2-driven signature scores. DDR mRNA expression and gene signature scores were evaluated using BCa-The Cancer Genome Atlas (n = 259) and IMvigor210 (n = 298) datasets, and their relationship to BCa subtypes, pathway enrichment, and immune deconvolution analyses was performed. The potential of DDR-driven signatures to predict ICT response was evaluated and independently validated through a statistical framework in bladder and lung cancer cohorts. All statistical tests were 2-sided. DDR1 and DDR2 showed mutually exclusive gene expression patterns in human tumors. DDR2high BCa exhibited activation of immune pathways and a high immune score, indicative of a T-cell-inflamed phenotype, whereas DDR1high BCa exhibited a non-T-cell-inflamed phenotype. In IMvigor210 cohort, tumors with high DDR1 (hazard ratio [HR] = 1.53, 95% confidence interval [CI] = 1.16 to 2.06; P = .003) or DDR2 (HR = 1.42, 95% CI = 1.01 to 1.92; P = .04) scores had poor overall survival. Of note, DDR2high tumors from IMvigor210 and CheckMate 275 (n = 73) cohorts exhibited poorer overall survival (HR = 1.56, 95% CI = 1.20 to 2.06; P < .001) and progression-free survival (HR = 1.77 95%, CI = 1.05 to 3.00; P = .047), respectively. This result was validated in independent cancer datasets. These findings implicate DDR1 and DDR2 driven signature scores in predicting ICT response.

Pharmacologic inhibition of discoidin domain Receptor 2 (DDR2) sensitizes homologous recombination proficient ovarian cancer models to treatment with olaparib (245)

Pharmacologic inhibition of discoidin domain Receptor 2 (DDR2) sensitizes homologous recombination proficient ovarian cancer models to treatment with olaparib (245)

Preprint Highlight: Collagen remodeling dictates pancreatic cancer bioenergetics and outcome through DDR1 activation or degradation.

Aberrant desmoplasia (e.g., collagen deposition) is a prominent hallmark of pancreatic ductal adenocarcinoma (PDAC) pathogenesis. The mechanisms and signaling pathways impacted by the prevalent increase in collagen deposition are poorly understood. This study demonstrated opposing roles of fibrolytic stroma (cleaved type I collagen) and inert stroma (intact type I collagen) in driving PDAC tumorigenicity. Cleaved type I collagen activates discoidin domain receptor 1 (DDR1), leading to increased tumor growth and liver metastases, macropinocytosis, metabolism, mitochondrial biogenesis, and poor patient outcomes. These effects were inhibited by intact type I collagen. This study describes new roles of DDR1-mediated regulation of macropinocytosis and mitochondrial biogenesis, delineates stromal states as oncogenic drivers of PDAC, and advances our understanding of aberrant desmoplasia.

Discoidin domain receptor 1(DDR1) promote intestinal barrier disruption in Ulcerative Colitis through tight junction proteins degradation and epithelium apoptosis

Background and aimsDiscoidin domain receptor 1 (DDR1) encodes a receptor tyrosine kinase involved in multiple physiological and pathological processes. DDR1 is expressed in the intestinal epithelium, but its role in Ulcerative Colitis (UC) is poorly understand. This study aimed to identify the function of DDR1 in maintaining the homeostasis of UC. MethodsThe DDR1 expression level in non-inflamed and inflamed colon samples from IBD patients were assessed. DDR1 knock-out (DDR1-/-) and wild-type (WT) mice were administered dextran sulfate sodium (DSS) to induce colitis and assessed based on colitis symptoms. In addition, intestinal epithelial barrier injury was induced by TNF-α and IFN-γ incubation to cell monolayers transfected with PCDH-DDR1 or pLKO.1-sh-DDR1–1 plasmids. The effect of DDR1 in regulating barrier integrity, tight junctions (TJ) protein status, and cell apoptosis was investigated in vivo and in vitro. Furthermore, the activation of the NF-κB p65-MLCK-p-MLC2 pathway was also investigated. ResultsDecreased DDR1 expression levels were observed at the inflamed sites compared with the non-inflamed. DDR1-/- mice had alleviated intestinal mucosal barrier injuries, upregulated TJ proteins, decreased epithelium apoptosis from DSS-induced colitis, and reduced proinflammatory cytokines production in the colon. These findings were further confirmed in vitro. DDR1 over-expression aggravated the TNF-α/IFN-γ-induced TJ disruption, while DDR1 shRNA prevented TJ damage even in the presence of JSH-23. DDR1 dependently destroyed the intestinal barrier via the NF-κB p65-MLCK-p-MLC2 pathway. ConclusionOur findings revealed that DDR1 regulated the intestinal barrier in colitis by modulating TJ proteins expression and epithelium apoptosis, making it a potential target of UC.

Discoidin domain receptor 1 is a potential target correlated with tumor invasion and immune infiltration in gastric cancer.

Discoidin domain receptor 1 (DDR1) has been demonstrated to be able to promote tumor invasion and metastasis and being closely related to tumor immune infiltration. However, DDR1 has rarely been studied in gastric cancer. Here, we primarily evaluated DDR1 expression in gastric cancer and its cell lines using multiple databases. Subsequently, the cancer prognosis was investigated in relation to DDR1 expression. After analysis, we discovered that DDR1 was highly expressed and significantly connected with poor prognosis in gastric cancer. To comprehensively understand the molecular mechanism of DDR1, we explored genes and proteins interacting with DDR1 in gastric cancer using databases. Additionally, we found that the expression level of DDR1 was inversely correlated with immune infiltration and significantly relative to various immune cell markers. Overall, DDR1 was implicated in invasion, metastasis, and immune infiltration of gastric cancer. Inhibition of DDR1 may have the potential to alleviate the strong invasiveness and metastasis of advanced gastric cancer. Meanwhile, immune exclusion by DDR1 may also provide a new strategy for improving the efficacy of immune checkpoints inhibitors (ICIs), such as programmed cell death protein 1 (PD-1) antibody.

New functions of DDR1 collagen receptor in tumor dormancy, immune exclusion and therapeutic resistance.

The tumor microenvironment facilitates cancer progression and therapeutic resistance. Tumor collagens and their architecture play an essential role in this process. However, little is known about the mechanisms by which tumor cells sense and respond to this extracellular matrix environment. Recently, the Discoidin Domain Receptor 1 (DDR1), a collagen receptor and tyrosine kinase has emerged as an important player in this malignant process, although the underlying signaling mechanisms remain unclear. Here, we review new DDR1 functions in tumor dormancy following dissemination, immune exclusion and therapeutic resistance induced by stromal collagens deposition. We also discuss the signaling mechanisms behind these tumor activities and the therapeutic strategies aiming at targeting these collagens-dependent tumor responses.

The tyrosine kinase inhibitor nilotinib targets the discoidin domain receptor DDR2 in calcific aortic valve stenosis.

Background and PurposeTyrosine kinase inhibitors (TKI) used to treat chronic myeloid leukaemia (CML) have been associated with cardiovascular side effects, including reports of calcific aortic valve stenosis. The aim of this study was to establish the effects of first and second generation TKIs in aortic valve stenosis and to determine the associated molecular mechanisms.Experimental ApproachHyperlipidemic APOE*3Leiden.CETP transgenic mice were treated with nilotinib, imatinib or vehicle. Human valvular interstitial cells (VICs) were isolated and studied in vitro. Gene expression analysis was perfromed in aortic valves from 64 patients undergoing aortic valve replacement surgery.Key ResultsNilotinib increased murine aortic valve thickness. Nilotinib, but not imatinib, promoted calcification and osteogenic activation and decreased autophagy in human VICs. Differential tyrosine kinase expression was detected between healthy and calcified valve tissue. Transcriptomic target identification revealed that the discoidin domain receptor DDR2, which is preferentially inhibited by nilotinib, was predominantly expressed in human aortic valves but markedly downregulated in calcified valve tissue. Nilotinib and selective DDR2 targeting in VICs induced a similar osteogenic activation, which was blunted by increasing the DDR2 ligand, collagen.Conclusions and ImplicationsThese findings suggest that inhibition of DDR2 by nilotinib promoted aortic valve thickening and VIC calcification, with possible translational implications for cardiovascular surveillance and possible personalized medicine in CML patients.

The dynamic roles of the bladder tumour microenvironment.

Bladder cancer is a prevalent but currently understudied cancer type and patient outcomes are poor when it progresses to the muscle-invasive stage. Current research in bladder cancer focuses on the genetic and epigenetic alterations occurring within the urothelial cell compartment; however, the stromal compartment receives less attention. Dynamic changes and intercellular communications occur in the tumour microenvironment (TME) of the bladder - a new concept and niche that we designate as the bladder TME (bTME) - during tumour evolution, metastatic progression and in the context of therapeutic response. Collagens and their cognate receptors, the discoidin domain receptors, have a role in various steps of the metastatic cascade and in immune checkpoint resistance. Furthermore, the presence of another TME niche, the metastatic TME (met-TME), is a novel concept that could support divergent progression of metastatic colonization in different organs, resulting in distant metastases with distinct characteristics and genetics from the primary tumour. The stroma has divergent roles in mediating therapeutic response to BCG immunotherapy and immune checkpoint inhibitors, as well as conventional chemotherapy or trimodality therapy (that is, maximal transurethral resection of bladder tumour, chemotherapy and radiotherapy). The local bTME and distant met-TME are currently conceptually and therapeutically unexploited niches that should be actively investigated. New biological insights from these TMEs will enable rational design of strategies that co-target the tumour and stroma, which are expected to improve the outcomes of patients with advanced bladder cancer.

Stroma-targeted nanoparticles that remodel stromal alignment to enhance drug delivery and improve the antitumor efficacy of Nab-paclitaxel in pancreatic ductal adenocarcinoma models

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. A dense desmoplastic and specifically aligned stroma plays integral roles in the progression of PDAC, and inhibits drug penetration to impede treatment. However, direct depletion of stromal components for PDAC therapy interferes with the stromal balance, possibly accelerating tumor progression. Specific fiber alignment of the extracellular matrix, the most significant type of stroma topology in PDAC, is an important feature of PDAC and often overlooked. Here, we found that the alignment of collagen fibers, as determined by second harmonic generation (SHG) imaging, negatively correlated with pancreatic cancer prognosis. We report an integrated, two-step strategy for PDAC treatment, utilizing pretreatment with polymer-lipid-peptide nanoparticles that deliver inhibitors of lysyl oxidase like 2 (LOXL2) and discoidin domain receptor 1 (DDR1), followed by treatment with albumin-bound-paclitaxel (Nab-paclitaxel). The LOXL2 and DDR1 inhibitors intervene with collagen crosslinking and matrix metallopeptidase 1 (MMP1) expression to remodel stromal alignment without decreasing the collagen content, thus facilitating the transport of Nab-paclitaxel through the stromal barrier to enhance drug penetration and accumulation in the PDAC tumor tissue. Through this mechanism, the combined strategy resulted in significant antitumor efficacy in PDAC orthotopic xenograft mice. The current work highlights the key role of stromal alignment in therapeutics transport through stromal barriers. The strategy of remodeling stromal alignment may represent a promising approach for improving drug delivery in other stroma-rich tumors and fibrosis-related diseases.

Glomerular basement membrane deposition of collagen α1(III) in Alport glomeruli by mesangial filopodia injures podocytes via aberrant signaling through DDR1 and integrin α2β1.

In Alport mice, activation of the endothelin A receptor (ETAR) in mesangial cells results in sub‐endothelial invasion of glomerular capillaries by mesangial filopodia. Filopodia deposit mesangial matrix in the glomerular basement membrane (GBM), including laminin 211 which activates NF‐κB, resulting in induction of inflammatory cytokines. Herein we show that collagen α1(III) is also deposited in the GBM. Collagen α1(III) localized to the mesangium in wild‐type mice and was found in both the mesangium and the GBM in Alport mice. We show that collagen α1(III) activates discoidin domain receptor family, member 1 (DDR1) receptors both in vitro and in vivo. To elucidate whether collagen α1(III) might cause podocyte injury, cultured murine Alport podocytes were overlaid with recombinant collagen α1(III), or not, for 24 h and RNA was analyzed by RNA sequencing (RNA‐seq). These same cells were subjected to siRNA knockdown for integrin α2 or DDR1 and the RNA was analyzed by RNA‐seq. Results were validated in vivo using RNA‐seq from RNA isolated from wild‐type and Alport mouse glomeruli. Numerous genes associated with podocyte injury were up‐ or down‐regulated in both Alport glomeruli and cultured podocytes treated with collagen α1(III), 18 of which have been associated previously with podocyte injury or glomerulonephritis. The data indicate α2β1 integrin/DDR1 co‐receptor signaling as the dominant regulatory mechanism. This may explain earlier studies where deletion of either DDR1 or α2β1 integrin in Alport mice ameliorates renal pathology. © 2022 Boys Town National Research Hospital. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Abstract 3235: The role of DDR2 in chemoresistant ovarian cancer

Abstract Ovarian cancer is the fifth leading cause of cancer death for women in the United States. As many as 80% of ovarian cancer patients experience recurrent disease and the majority of recurrences become resistant to treatment. Once patients no longer respond to chemotherapy, there are minimal treatment options and they succumb to their disease. Therefore, there is a need to create new targeted therapies to overcome chemoresistance in ovarian cancer and improve patient survival. We have assembled a tumor microarray from 164 patient tumors to characterize the changes in protein expression that lead to resistance in clinical samples. We have found using IHC staining, that patients with high tyrosine kinase receptor discoidin domain receptor 2 (DDR2) protein expression (>70%) have significantly shorter overall survival times regardless of stage at diagnosis (HR= 2.108, p=0.002) as well as reduced platinum free interval (p=0.046). Additionally, platinum refractory tumors have higher DDR2 protein expression than platinum sensitive tumors (p=0.036). To further understand the mechanisms of chemoresistance, we created a novel, chemoresistant, syngeneic, mouse ovarian cancer cell line derived from ID8 trp53-/-BRCA2-/- GFP LUC cells from Walton et. al 2016, and have designated them CHRP5. DDR2 expression assessed via western blot increased significantly in the chemoresistance cells, suggesting that DDR2 is associated with chemoresistance. We knocked down DDR2 using a stable shRNA transfection in CHRP5 and used MTS survival assays to determine if decreased DDR2 expression increases sensitivity to chemotherapy. CHRP5 shDDR2 cells were significantly more sensitive to carboplatin than CHRP5 shControl cells (CHRP5 shControl IC50=213.6uM, CHRP5 shDDR2 IC50=128.5uM, p<0.000001), suggesting that DDR2 is involved in regulating chemoresistance in these cells. Additionally, we have submitted matched chemoresistant and chemosensitive mouse tumor samples for RNA-sequencing. We will use this data to determine which chemoresistant mechanisms are utilized, and if DDR2 is involved in regulating those mechanisms. In the future, we plan to rescue DDR2 in the knockdown cells to confirm that off target effects are not influencing the change in sensitivity. We also have access to a specific, allosteric inhibitor of DDR2 and plan to use this drug to determine if inhibiting DDR2 pharmacologically can overcome chemoresistance and reduce tumor burden in vivo and in vitro. In conclusion, DDR2 is more highly expressed in chemoresistant patients, and higher DDR2 expression correlates with reduced survival and platinum free interval. Additionally, knocking down DDR2 in chemoresistant cells increases sensitivity to chemotherapy. Therefore, DDR2 is a potential new target for ovarian cancer therapy and may be targeted to overcome chemoresistant disease and extend patient survival. Citation Format: Alyssa Oplt, Elizabeth Stock, Hollie Noia, Patrick Cannon, Gregory Longmore, Katherine C. Fuh. The role of DDR2 in chemoresistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3235.

Abstract 3190: Investigating tumor-mesothelial cell interactions during ovarian cancer metastasis

Abstract Introduction: Ovarian cancer is the leading cause of gynecological cancer-related deaths. The propensity for metastasis is a driving factor for the poor outcomes associated with this disease, but there is currently no effective therapy targeting metastasis. Work from our lab has demonstrated that stromal cell expression of the receptor tyrosine kinase Discoidin Domain Receptor 2 (DDR2) promotes ovarian cancer metastasis. One stromal compartment that expresses DDR2 is the mesothelial cell layer that surrounds the organs of the peritoneum - the most common location of ovarian cancer metastasis. Although epithelial in origin, mesothelial cells can adopt mesenchymal properties during metastasis and become active participants in the process. Therefore, we hypothesize that mesothelial cell expression of DDR2 promotes stabilization of a mesenchymal phenotype in mesothelial cells, which facilitates ovarian cancer metastasis. Methods: Human peritoneal mesothelial cells (HPMCs) were isolated from patient omentum samples. HPMCs were immortalized using lentivirus expressing SV40 large T antigen followed by short hairpin control and DDR2 knockdown transfections. qPCR was used to assess transcription and immunoblotting was used to assess protein expression. ELISAs were completed to observe changes in MMP-2 secretion. C57BL6/J mice are used for in vivo studies. Results: In vitro we have found that DDR2-expressing human peritoneal mesothelial cells promote tumor cell clearance through the mesothelial cell layer. Further, mesothelial cell DDR2 increases mesenchymal-associated gene transcription and signaling, including the mesenchymal associated transcription factor SNAI1 and collagen 1. Mesothelial cell DDR2 expression also leads to increased secretion of the protease MMP-2, which is known to promote metastasis. To determine whether mesothelial cell DDR2 expression contributes to metastasis, we are creating a mesothelial cell-specific DDR2 knockout mouse and control mouse. To do so, we are breeding WT1CreERT2/+ mice as a mesothelial cell specific driver of Cre recombination with DDR2 floxed mice to knockout DDR2 as a result of Cre recombination, and Ai14 mice as a Cre reporter as they express tdTomato only in the presence of Cre. After validation of the model, syngeneic ovarian cancer cells will be intraperitoneally injected and tumor burden, ECM structure, and signaling changes will be compared between knockout and control mice. Conclusions: This work will increase our understanding of mesothelial cells’ contribution to metastasis with the possibility of identifying inhibition of DDR2 as a therapeutic target for ovarian cancer patients. Citation Format: Angela Schab, Elena Lomonosova, Isaac Cooper, Stephanie Teng, Zainab Ibitoye, Danny Wilke, Hollie Noia, Maggie Mullen, Gregory Longmore, Katherine Fuh. Investigating tumor-mesothelial cell interactions during ovarian cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3190.

Placenta as a source for progenitor cells for cardiac cell-based therapies

Objective: Cell-based therapies utilizing mesenchymal and cardiac progenitor cells have demonstrated promising results in the treatment of congenital heart disease. We hypothesize that autologous human placental-derived progenitor cells share similar characteristics to cardiac progenitor cells (CPC) derived from autologous bone marrow or cardiac sources.Methods: Fetal portion of the placenta was harvested at the time of delivery from newborns (N = 5), and cells were isolated and expanded from the amnion and chorion layers. Flow cytometry and multi-lineage differentiation potential assays were used to characterize placental-derived progenitor cells. Placenta derived sphere cells were generated and phenotypic and functional characteristics were analyzed.Results: CD90, CD105, and Vimentin were expressed in <10% placental-derived progenitor cells, and differentiation into mesodermal lineages was not observed. However, placental-derived progenitor cells were able to differentiate into smooth muscle and cardiomyocyte lineages. In placenta derived sphere cells, >65% expressed cardiac lineage marker (SIRPA), but <15% expressed Discoidin domain receptor 2 (DDR2). Compared to placental-derived progenitor cells, placenta derived sphere cells expressed higher levels of cardiac transcription factors, cardiac ion channel genes and cardiac structural genes.Conclusions: Placental progenitor cells demonstrate similar characteristics to CPC currently utilized in several clinical trials that can serve as a readily available autologous source for cardiac cell therapy.

Association of DDR1 with immune exclusion and outcomes in non-small cell lung cancer.

e20553 Background: Discoidin domain receptor 1 (DDR1) is a collagen receptor with tyrosine kinase activity. Although DDR1 has been reported to implicated in cancer progression and metastases, the underlying mechanism remains poorly characterized and its prognostic value is also contradictory in non-small cell lung cancer (NSCLC). Methods: Clinical and DDR1 mRNA expression data of 1925 patients with NSCLC were obtained from 14 publicly available datasets utilizing an online tool KM-plotter. All patients were split into 2 groups by median expression of DDR1. The Kaplan-Meier curve and log-rank test, and Cox regression analyses were used to examine the association between DDR1 expression and overall survival (OS). The table shows 48 immune-regulatory genes classified into 4 signatures associated with activated T cells, immune cytolytic activity, and antitumor immunity. Expression data of these genes for 994 patients with NSCLC were gathered from the TCGA Pan-Cancer Atlas. Abundance data of various immune cell types in tumor microenvironment for the TCGA patients were inferred using xCell, and then immune infiltration extent was calculated as immune score. Associations of DDR1 with immune genes expression and immune score were determined with Spearman rank correlation. Results: DDR1 overexpression was significantly associated with inferior OS in this large-scale cohort (median, 62 vs 78.5 months; hazard ratio [HR], 1.16; 95% CI, 1.02-1.31; P = .02). Of note, multivariable Cox model indicated DDR1 overexpression was an independent risk factor for OS (HR, 1.41; 95% CI, 1.01-1.98; P = .046), controlling for potential confounders (histology, stage, sex, and smoking history). Of the 48 immune-regulatory genes, 44 (92%) showed significant negative correlations with DDR1 expression (all P &lt; .05), implying the role of DDR1 in decreasing immune infiltration into tumor microenvironment. Further, higher immune score was observed in tumors underexpressing DDR1 (correlation coefficient, -0.44; P &lt; .001), more directly demonstrating the link between DDR1 and immune infiltration. Conclusions: To our knowledge, this is the largest study to evaluate the prognostic role of DDR1 expression in NSCLC. Our results suggest that DDR1 overexpression may predict poor outcomes and a possible mechanistic explanation regarding this role may be immune exclusion instigated by DDR1. Thus, targeting DDR1 expression to abrogate immune exclusion warrants further investigation.[Table: see text]

Tumor specifically internalizing peptide ‘HN-1’: Targeting the putative receptor retinoblastoma-regulated discoidin domain receptor 1 involved in metastasis

BACKGROUNDLess than 0.5% of intravenously injected drugs reach tumors, contributing to side effects. To limit damage to healthy cells, various delivery vectors have been formulated; yet, previously developed vectors suffer from poor penetration into solid tumors. This issue was resolved by the discovery of HN-1 peptide isolated via biopanning a phage-display library. HN-1 targets human head and neck squamous cell carcinoma (HNSCC) (breast, thyroid; potentially lung, cervix, uterine, colon cancer), translocates across the cell membrane, and efficiently infiltrates solid tumors. HN-1 peptide has been conjugated to various anticancer drugs and imaging agents though the identity of its receptor remained enigmatic.AIMTo decipher the clues that pointed to retinoblastoma (Rb)-regulated discoidin-domain receptor 1 as the putative receptor for HN-1 is described.METHODSHN-1 peptide was synthesized and purified using reverse-phase high-performance liquid chromatography and gel electrophoresis. The predicted mass was confirmed by mass spectroscopy. To image the 3-dimensional structure of HN-1 peptide, PyMOL was used. Molecular modeling was also performed with PEP-FOLD3 software via RPBS bioinformatics web portal (INSERM, France). The immunohistochemistry results of discoidin domain receptor 1 (DDR1) protein were obtained from the publicly accessible database in the Human Protein Atlas portal, which contained the images of immunohistochemically labeled human cancers and the corresponding normal tissues.RESULTSThe clues that led to DDR1 involved in metastasis as the putative receptor mediating HN-1 endocytosis are the following: (1) HN-1 is internalized in phosphate-buffered saline and its uptake is competitively inhibited; (2) HN-1 (TSPLNIHNGQKL) exhibits similarity with a stretch of amino acids in alpha5 beta3 integrin (KLLITIHDRKEF). Aside from two identical residues (Ile-His) in the middle, the overall distribution of polar and nonpolar residues throughout the sequences is nearly identical. As HN-1 sequence lacks the Arg-Gly-Asp motif recognized by integrins, HN-1 may interact with an "integrin-like" molecule. The tertiary structure of both peptides showed similarity at the 3-dimensional level; (3) HN-1 is internalized by attached cells but not by suspended cells. As culture plates are typically coated with collagen, collagen-binding receptor (expressed by adherent but not suspended cells) may represent the receptor for HN-1; (4) DDR1 is highly expressed in head and neck cancer (or breast cancer) targeted by HN-1; (5) Upon activation by collagen, DDR1 becomes internalized and compartmentalized in endosomes consistent with the determination of ’energy-dependent clathrin-mediated endocytosis’ as the HN-1 entry route and the identification of HN-1 entrapped vesicles as endosomes; and (6) DDR1 is essential for the development of mammary glands consistent with the common embryonic lineage rationale used to identify breast cancer as an additional target of HN-1. In summary, collagen-activated tyrosine kinase receptor DDR1 overexpressed in HNSCC assumes a critical role in metastasis. Further studies are warranted to assess HN-1 peptide’s interaction with DDR1 and the therapeutic potential of treating metastatic cancer. Additionally, advances in delivery (conformation, endocytic mechanism, repertoire of targeted cancers of HN-1 peptide), tracking (HN-1 conjugated imaging agents), and activity (HN-1 conjugated therapeutic agents) are described.CONCLUSIONThe discovery of DDR1 as HN-1 peptide’s putative receptor represents a significant advance as it enables identification of metastatic cancers or clinical application of previously developed therapeutics to block metastasis.

Discoidin domain receptor 1 promotes lung adenocarcinoma migration via the AKT/snail signaling axis.

Discoidin domain receptor 1 (DDR1), a member of receptor tyrosine kinase, has been implicated in tumor progression. However, the function and underlying mechanism of DDR1 in lung adenocarcinoma (LUAD) progression is unclear. Thus, we explored the molecular regulatory mechanism of DDR1 in the migration of LUAD. Transwell assays, wound healing assays and xenograft tumor assays were performed to study the function of DDR1 in the progression of LUAD. Immunoblotting and quantitative real-time polymerase chain reaction (RT-qPCR) were used to detect the expression levels of genes. Co-immunoprecipitation (co-IP) assays were performed to detect the interaction between DDR1 and AKT. Immunofluorescence and immunohistochemistry assays were used to determine the expression level of proteins in cells and tissues, respectively. DDR1 expression was significantly higher in LUAD tissues than in normal lung tissues, and the level of DDR1 was inversely correlated with prognosis in patients. We found that DDR1 promoted the migration and invasion of LUAD cells in vitro. Furthermore, ectopic expression of DDR1 in LUAD cells altered EMT-related markers expression. Importantly, the DDR1 protein interacted with AKT and phosphorylated AKT. The AKT inhibitor MK2206 interrupted Snail upregulation in DDR1-overexpressing LUAD cells. Finally, our study revealed that depletion of DDR1 attenuated LUAD cell migration in a tumor xenograft mouse model. Our findings uncovered that a high abundance of DDR1 increased the migration and invasion capability of LUAD cells via the AKT/Snail signaling axis and indicated that DDR1 could be a potential target for treating LUAD.

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.

The extracellular matrix and immunity: breaking the old barrier in cancer

Extracellular matrix (ECM) is an integral component of solid cancers; however, the impact of the ECM on antitumor immunity has remained elusive. Sun and colleagues now demonstrate that discoidin domain receptor 1-mediated collagen assembly can exclude T cells from tumors. Together, recent studies highlight ECM as an active regulator of immunity in cancer.