A putative role for Discoidin Domain Receptor 1 in cancer chemoresistance

Bivalent activity of super-enhancer RNA LINC02454 controls 3D chromatin structure and regulates glioma sensitivity to temozolomide

Glioma cell sensitivity to temozolomide (TMZ) is critical for effective treatment and correlates with patient survival, although mechanisms underlying this activity are unclear. Here, we reveal a new mechanism used by glioma cells to modulate TMZ sensitivity via regulation of SORBS2 and DDR1 genes by super-enhancer RNA LINC02454. We report that LINC02454 activity increases glioma cell TMZ sensitivity by maintaining long-range chromatin interactions between SORBS2 and the LINC02454 enhancer. By contrast, LINC02454 activity also decreased glioma cell TMZ sensitivity by promoting DDR1 expression. Our study suggests a bivalent function for super-enhancer RNA LINC02454 in regulating glioma cell sensitivity to TMZ.

Complex roles of discoidin domain receptor tyrosine kinases in cancer

Discoidin domain receptors, DDR1 and DDR2 are members of the receptor tyrosine kinase (RTK) family that serves as a non-integrin collagen receptor and were initially identified as critical regulators of embryonic development and cellular homeostasis. In recent years, numerous studies have focused on the role of these receptors in disease development, in particular, cancer where they have been reported to augment ECM remodeling, invasion, drug resistance to facilitate tumor progression and metastasis. Interestingly, accumulating evidence also suggests that DDRs promote apoptosis and suppress tumor progression in various human cancers due to which their functions in cancer remain ill-defined and presents a case of an interesting therapeutic target. The present review has discussed the role of DDRs in tumorigenesis and the metastasis.

Inhibition of DDR1 enhances in vivo chemosensitivity in KRAS-mutant lung adenocarcinoma

Platinum-based chemotherapy in combination with immune-checkpoint inhibitors is the current standard of care for patients with advanced lung adenocarcinoma (LUAD). However, tumor progression evolves in most cases. Therefore, predictive biomarkers are needed for better patient stratification and for the identification of new therapeutic strategies, including enhancing the efficacy of chemotoxic agents. Here, we hypothesized that discoidin domain receptor 1 (DDR1) may be both a predictive factor for chemoresistance in patients with LUAD and a potential target positively selected in resistant cells. By using biopsies from patients with LUAD, KRAS-mutant LUAD cell lines, and in vivo genetically engineered KRAS-driven mouse models, we evaluated the role of DDR1 in the context of chemotherapy treatment. We found that DDR1 is upregulated during chemotherapy both in vitro and in vivo. Moreover, analysis of a cohort of patients with LUAD suggested that high DDR1 levels in pretreatment biopsies correlated with poor response to chemotherapy. Additionally, we showed that combining DDR1 inhibition with chemotherapy prompted a synergistic therapeutic effect and enhanced cell death of KRAS-mutant tumors in vivo. Collectively, this study suggests a potential role for DDR1 as both a predictive and prognostic biomarker, potentially improving the chemotherapy response of patients with LUAD.

Meeting report – first discoidin domain receptors meeting

For the first time, a meeting dedicated to the tyrosine kinase receptors DDR1 and DDR2 took place in Bordeaux, a famous and historical city in the south of France. Over the course of 3 days, the meeting allowed 60 participants from 11 different countries to exchange ideas and their new findings about these unique collagen receptors, focusing on their role in various physiological and pathological conditions and addressing their mechanisms of regulation and signalling. The involvement of these receptors in different pathologies was also considered, with emphasis on cancer development and potential therapeutic applications. Here, we summarize the key elements of this meeting.

Altered Expression of DDR1 in Clear Cell Renal Cell Carcinoma Correlates With miR-199a/b-5p and Patients' Outcome

BACKGROUND/AIM

Accumulating evidence suggests that discoidin domain receptor tyrosine kinase 1 (DDR1) has an oncogenic role. Therefore, the aim of this study was to evaluate the potential utility of DDR1 and its post-transcriptional repressors, miR-199a-5p and miR-199b-5p, as prognostic factors in clear cell renal cell carcinoma (ccRCC).

PATIENTS AND METHODS

The expression of DDR1 in tumor and normal renal tissues of 56 patients with ccRCC was assessed by reverse transcription quantitative polymerase chain reaction, western blotting and immunohistochemistry. Renal cancer cells were transfected with specific RNA sequences to validate DDR1 as a putative miR-199a/b-5p target.

RESULTS

Decreased DDR1 mRNA and protein, as well as miR-199a/b-5p levels were found in ccRCC. Low DDR1 protein was associated with higher nuclear grade and shorter overall survival. DDR1 immunoreactivity was elevated in the nuclei and unchanged in the membrane/cytoplasmic compartment of tumor cells. DDR1 levels correlated with those of miR-199a/b-5p. In addition, we validated DDR1 as a target gene for miR-199a/b-5p in renal cancer cell lines.

CONCLUSION

DDR1 expression is altered in ccRCC, but our findings do not support its oncogenic role. In-depth investigation will be necessary to elucidate the exact role and potential utility of miR-199a/b-5p in ccRCC.

Cell-Matrix Interactions and Matricrine Signaling in the Pathogenesis of Vascular Calcification

Vascular calcification is a complex pathological process occurring in patients with atherosclerosis, type 2 diabetes, and chronic kidney disease. The extracellular matrix, via matricrine-receptor signaling plays important roles in the pathogenesis of calcification. Calcification is mediated by osteochondrocytic-like cells that arise from transdifferentiating vascular smooth muscle cells. Recent advances in our understanding of the plasticity of vascular smooth muscle cell and other cells of mesenchymal origin have furthered our understanding of how these cells transdifferentiate into osteochondrocytic-like cells in response to environmental cues. In the present review, we examine the role of the extracellular matrix in the regulation of cell behavior and differentiation in the context of vascular calcification. In pathological calcification, the extracellular matrix not only provides a scaffold for mineral deposition, but also acts as an active signaling entity. In recent years, extracellular matrix components have been shown to influence cellular signaling through matrix receptors such as the discoidin domain receptor family, integrins, and elastin receptors, all of which can modulate osteochondrocytic differentiation and calcification. Changes in extracellular matrix stiffness and composition are detected by these receptors which in turn modulate downstream signaling pathways and cytoskeletal dynamics, which are critical to osteogenic differentiation. This review will focus on recent literature that highlights the role of cell-matrix interactions and how they influence cellular behavior, and osteochondrocytic transdifferentiation in the pathogenesis of cardiovascular calcification.