br Materials and methods br Results
Materials and methods
Discussion Recently, circRNAs have been found to play important diagnostic or prognostic roles in different tumors. For example, aberrant expression levels of different circRNAs are found in ovarian cancer, lung cancer, renal cancer, gastric cancer and participate in tumor occurrence and progression (Bao et al., 2019; Hu et al., 2018; Zhou et al., 2018; H. Pan et al., 2018, Z.H. Pan et al., 2018). A previous study has also confirmed that elevated circ-001569 is presented in colorectal cancer tissues and the depleted circ-001569 could repress cell proliferation and invasion and induce apoptosis via competitively binding and inhibiting miR-145 activity (Xie et al., 2016). As for the functions of circ-LAMP1, gain/loss-of-function experiments found circ-LAMP1 significantly boosted cell growth via inhibiting cell apoptosis in T-LBL cells. The circRNAs, known as miRNAs sponge, modulate gene expression as competing endogenous RNA and expression of miRNA-targeted transcripts in several eukaryotes (Xuan et al., 2016). For instance, silenced circ-0067934 obviously restricts the proliferation, migration and invasion of hepatocellular carcinoma 8-pCPT-2-O-Me-cAMP-AM and tumor growth, while provokes cell apoptosis by suppressing miR-1324, which targeted the 3′-UTR of frizzled class receptor 5 mRNA and subsequently inhibited the activation of Wnt/β-catenin signal (Zhu et al., 2018). In this work, we demonstrated the important regulatory actions of circ-LAMP1/miR-615-5p/DDR2 axis in T-LBL development and progression. MiR-615-5p is frequently downregulated and acts as a cancer suppressor in hepatocellular carcinoma, pancreatic adenocarcinoma, etc. (Wu et al., 2016; Jiang et al., 2016). What\'s more, it is reported that miR-615-5p could be regulated by circRNAs or lncRNAs at posttranscriptional level (Chen et al., 2019; H. Pan et al., 2018, Z.H. Pan et al., 2018). In this project, we identified DDR2 as the downstream target of miR-615-5p. DDR2 is a member of the receptor tyrosine kinase (RTK) family (Leitinger and Kwan, 2006; Carafoli et al., 2009). Various evidence documented its oncogenic role in human malignancies. Velmurugan et al. uncovered that overexpressed DDR2 is correlated with lymph node metastasis in oral squamous cell carcinoma (Velmurugan et al., 2018). Additionally, DDR2 expression is linked to a high frequency of peritoneal dissemination and unfavorable prognosis in colorectal cancer (Sasaki et al., 2017). However, the role of DDR2 in T-LBL was unknown before our exploration. We demonstrated that the oncogenic functions of circ-LAMP1 are partially attributed to the modulation of miR-615-5p/DDR2 axis. Nevertheless, due to the cellular characteristics of T-LBL cells. The metastasis capacity was not explored in the present study. In addition, due to the limit number of enrolled patients in our study, the prognostic role of circ-LAMP1 was not investigated. Along with future studies, circ-LAMP1 may be used as an effective therapeutic target and prognostic biomarker for the patients with T-LBL.
Declaration of interest statement
Introduction Collagen is widely used in tissue engineering [, , ]. It is the most abundant protein in the human body and is a major constituent of the extracellular matrix (ECM), providing natural structural and biological support for cells . The mechanical properties of collagen-based biomaterials can be tailored to match the strength, stiffness and architecture of the host tissue. Chemical crosslinking of a collagen-based scaffold using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS), is widely used to increase its stiffness and to resist swelling in biological media [, , ]. However, we have previously shown that such crosslinking ablated the recognition of the collagen-binding integrins (α1β1, α2β1, α10β1 and α11β1) and led to a dramatic loss of cell adhesion compared to native type I collagen [, , , , ], as a result of consumption of the glutamate residues in integrin binding Gxx\'GEx\'\' motifs [13,14] in forming isopeptide bonds with lysines. Other collagen receptors might also be affected if their binding sequences contain aspartate, glutamate or lysine residues, or if they are adjacent to such EDC/NHS-sensitive residues. We show in this study that DDR2 and the A3 domain of VWF are affected by EDC/NHS crosslinking due to the presence of adjacent glutamate and lysine, even though their immediate binding site in collagen lacks such residues. For use in regenerative medicine, these materials must support cell attachment, subsequent differentiation and proliferation to fulfil their physiological function in the target tissue. Previously, we reported a methodology to derivatise collagen films with photoreactive triple-helical peptides (THPs) containing the GFOGER integrin binding motif . THPs mimic the natural structure of collagen by adopting a triple helix conformation, essential for recognition by collagen binding receptors. THPs, however, remain rarely used in tissue engineering and, although examples can be found on various surfaces [16,17], their incorporation into collagen-based materials has only been investigated in this laboratory, to our knowledge. In our hands, this led to complete restoration of integrin mediated cell binding and spreading to EDC/NHS crosslinked collagen films .