The Extracellular Matrix in Soft Tissue Sarcomas: Pathobiology and Cellular Signalling

Soft tissue sarcomas are rare cancers of mesenchymal origin or differentiation comprising over 70 different histological subtypes. Due to their mesenchymal differentiation, sarcomas are thought to produce and deposit large quantities of extracellular matrix (ECM) components. Interactions between ECM ligands and their corresponding adhesion receptors such as the integrins and the discoidin domain receptors play key roles in driving many fundamental oncogenic processes including uncontrolled proliferation, cellular invasion and altered metabolism. In this review, we focus on emerging studies that describe the key ECM components commonly found in soft tissue sarcomas and discuss preclinical and clinical evidence outlining the important role that these proteins and their cognate adhesion receptors play in sarcomagenesis. We conclude by providing a perspective on the need for more comprehensive in-depth analyses of both the ECM and adhesion receptor biology in multiple histological subtypes in order to identify new drug targets and prognostic biomarkers for this group of rare diseases of unmet need.

Prognostic and Clinicopathologic Significance of Discoidin Domain Receptors in Different Human Malignancies: A Meta-Analysis

<b><i>Background:</i></b> Discoidin domain receptors (DDRs) belong to the receptor tyrosine kinases family and are activated by different types of collagens, which play roles in various physiological processes. An abnormal expression of DDRs is reported in different types of cancers. Despite many reports about the association and roles of high DDR expression levels in cancers, the prognostic values of DDRs are still unclear. This meta-analysis was performed to evaluate the prognostic effect of DDRs in different tissue cancers. <b><i>Method:</i></b> A literature search was performed in several related databases to find eligible English articles. Based on our research, 20 appropriate studies with 2,602 patients were selected till October 5, 2020. The pooled hazard ratio (HR) with a corresponding 95% confidence interval (CI) was computed to evaluate the strength of correlation between DDRs and survival of cancer patients. <b><i>Result:</i></b> Pooling results showed that a high DDR expression was significantly associated with poorer overall survival (OS) (HR = 1.304, 95% CI 1.007–1.69, <i>p</i> = 0.04). Subgroup analysis based on cancer type revealed a significant link between a high DDR expression level and poor OS both in gastrointestinal (pooled HR = 1.78, 95% CI 1.214–2.624, <i>p</i> = 0.003) and urological cancers (pooled HR = 1.42, 95% CI 1.062–1.82, <i>p</i> = 0.018). <b><i>Conclusion:</i></b> Our meta-analysis results suggest that high DDRs expression has the potential to be used as a biomarker of poor prognosis in cancers.

Inhibition of discoidin domain receptors by imatinib prevented pancreatic fibrosis demonstrated in experimental chronic pancreatitis model

Discoidin domain receptors (DDR1 and DDR2) are the collagen receptors of the family tyrosine kinases, which play significant role in the diseases like inflammation, fibrosis and cancer. Chronic pancreatitis (CP) is a fibro-inflammatory disease in which recurrent pancreatic inflammation leads to pancreatic fibrosis. In the present study, we have investigated the role of DDR1 and DDR2 in CP. The induced expression of DDR1 and DDR2 was observed in primary pancreatic stellate cells (PSCs) and cerulein-induced CP. Subsequently, the protective effects of DDR1/DDR2 inhibitor, imatinib (IMT) were investigated. Pharmacological intervention with IMT effectively downregulated DDR1 and DDR2 expression. Further, IMT treatment reduced pancreatic injury, inflammation, extracellular matrix deposition and PSCs activation along with inhibition of TGF-β1/Smad signaling pathway. Taken together, these results suggest that inhibition of DDR1 and DDR2 controls pancreatic inflammation and fibrosis, which could represent an attractive and promising therapeutic strategy for the treatment of CP.

P056 Crohn’s Disease associated fibrosis modulates the expression of collagen receptors

Background Crohn’s Disease (CD) patients often develop stenotic complications as immunomodulatory treatments do not prevent the fibrogenic response in the affected tissues, where a dysregulated activation of stromal cells provokes an excessive deposition of extracellular matrix (ECM). Recent evidences support the notion that local cells can sense the consequent alterations in tissue structure and rigidity through receptors that respond to some ECM components, and this may perpetuate the fibrogenic process even in the absence of inflammation. We aim to analyse the relevance of these signalling pathways in the fibrotic process associated to CD. Methods We obtained fibrotic ileal tissues from CD patients and healthy ileal samples from colon carcinoma patients (control), and analysed the expression (RT-PCR, IHQ) of collagen receptors (integrins, discoidin domain receptors/DDR) and of markers for some stromal cells (fibroblasts, endothelial cells). The relationship between these sets of data was analysed by Pearson’s correlation and the results organized as a correlation matrix. The expression of collagen receptors was also analysed in endothelial cells (HUVEC) treated with TGFβ 2 (1ng/ml, 48h). Results Ileal samples from CD patients present a differential gene expression of collagen receptors (Fig 1), with increased levels of ITGA10, ITGA11 and DDR2, and reduced expression of DDR1. In CD tissues, the expression of ITGA11 and DDR1 showed a significant correlation, positive and negative respectively, with that of endothelial markers (Fig 2). These correlations do not occur in control tissues. Integrin-α11 was detected in endothelial cells of submucosal vessels (IHQ). In HUVEC, TGFβ 2 increased the expression of ITGA11 (8.1±0.7 fold induction, p&lt;0.01) and reduced that of DDR1 (0.74±0.06 fold induction, p&lt;0.01), without affecting that of the other collagen receptors. Conclusion Intestinal tissues from CD patients affected by fibrosis present an altered pattern of expression of collagen receptors, which suggests a regulatory role of the ECM in the fibrotic response, while the correlation analysis and the changes induced by the fibrotic cytokine TGFβ in endothelial cells insinuates a particular relevance of these stromal cells in this process.

The Yin and Yang of Discoidin Domain Receptors (DDRs): Implications in Tumor Growth and Metastasis Development

The tumor microenvironment is a complex structure composed of the extracellular matrix (ECM) and nontumoral cells (notably cancer-associated fibroblasts (CAFs) and immune cells). Collagens are the main components of the ECM and they are extensively remodeled during tumor progression. Some collagens are ligands for the discoidin domain receptor tyrosine kinases, DDR1 and DDR2. DDRs are involved in different stages of tumor development and metastasis formation. In this review, we present the different roles of DDRs in these processes and discuss controversial findings. We conclude by describing emerging DDR inhibitory strategies, which could be used as new alternatives for the treatment of patients.

Discoidin Domain Receptors 1 Inhibition Alleviates Osteoarthritis via Enhancing Autophagy

We recently reported that the chondrocyte-specific knockout of discoidin domain receptors 1 (Ddr1) delayed endochondral ossification (EO) in the growth plate by reducing the chondrocyte hypertrophic terminal differentiation, and apoptosis. The biologic and phenotypic changes in chondrocytes in the articular cartilage with osteoarthritis (OA) are similar to the phenomena observed in the process of EO. Additionally, autophagy can promote chondrocyte survival and prevent articular cartilage from degradation in OA. On this basis, we explored the effect of Ddr1 inhibition on OA prevention and further investigated the roles of autophagy in treating OA with a Ddr1 inhibitor (7 rh). The anterior cruciate ligament transection (ACLT)–OA model was used to investigate the role of 7 rh in vivo. Forty 8-week-old mice were randomly assigned to four groups, including the sham group, ACLT group, and two treated groups (ACLT with 7 rh 6.9 nM or 13.8 nM). According to the study design, normal saline or 7 rh were intra-articular (IA) injected into studied knees 3 times per week for 2 weeks and then once per week for 4 weeks. The results showed that 7 rh treatment significantly improved the functional performances (the weight-bearing ability and the running endurance), decreased cartilage degradation, and also reduced the terminal differentiation markers (collagen type X, Indian hedgehog, and matrix metalloproteinase 13). Moreover, 7 rh decreased chondrocyte apoptosis by regulating chondrocyte autophagy through reducing the expression of the mammalian target of rapamycin and enhancing the light chain 3 and beclin-1 expression. These results demonstrated that the IA injection of 7 rh could reduce the chondrocyte apoptosis and promote chondrocyte autophagy, leading to the attenuation of cartilage degradation. Our observations suggested that the IA injection of 7 rh could represent a potential disease-modifying therapy to prevention OA progression.