Extracellular Matrix Alterations in Metastatic Processes. Int J Mol Sci. 2019;20. [PMID: 31591367 PMCID: PMC6802000 DOI: 10.3390/ijms20194947]

Roles of Proteoglycans and Glycosaminoglycans in Cancer Development and Progression

The extracellular matrix (ECM) spatiotemporally controls cell fate; however, dysregulation of ECM remodeling can lead to tumorigenesis and cancer development by providing favorable conditions for tumor cells. Proteoglycans (PGs) and glycosaminoglycans (GAGs) are the major macromolecules composing ECM. They influence both cell behavior and matrix properties through direct and indirect interactions with various cytokines, growth factors, cell surface receptors, adhesion molecules, enzymes, and glycoproteins within the ECM. The classical features of PGs/GAGs play well-known roles in cancer angiogenesis, proliferation, invasion, and metastasis. Several lines of evidence suggest that PGs/GAGs critically affect broader aspects in cancer initiation and the progression process, including regulation of cell metabolism, serving as a sensor of ECM's mechanical properties, affecting immune supervision, and participating in therapeutic resistance to various forms of treatment. These functions may be implemented through the characteristics of PGs/GAGs as molecular bridges linking ECM and cells in cell-specific and context-specific manners within the tumor microenvironment (TME). In this review, we intend to present a comprehensive illustration of the ways in which PGs/GAGs participate in and regulate several aspects of tumorigenesis; we put forward a perspective regarding their effects as biomarkers or targets for diagnoses and therapeutic interventions.

Neutrophils: Accomplices in metastasis

Metastasis is a critical cause of treatment failure and death in patients with advanced malignancies. Tumor cells can leave the primary site and enter the bloodstream; these circulating tumor cells then colonize target organs by overcoming blood shear stress, evading immune surveillance, and silencing the offensive capabilities of immune cells, eventually forming metastatic foci. From leaving the primary focus to the completion of distant metastasis, malignant tumor cells are supported and/or antagonized by certain immune cells. In particular, it has been found that myeloid granulocytes play an important role in this process. This review therefore aims to comprehensively describe the significance of neutrophils in solid tumor metastasis in terms of their supporting role in initiating the invasion and migration of tumor cells and assisting the colonization of circulating tumor cells in distant target organs, with the hope of providing insight into and ideas for anti-tumor metastasis treatment of tumor patients.

Intrinsic and Extrinsic Modulators of the Epithelial to Mesenchymal Transition: Driving the Fate of Tumor Microenvironment

The epithelial to mesenchymal transition (EMT) is an evolutionarily conserved process. In cancer, EMT can activate biochemical changes in tumor cells that enable the destruction of the cellular polarity, leading to the acquisition of invasive capabilities. EMT regulation can be triggered by intrinsic and extrinsic signaling, allowing the tumor to adapt to the microenvironment demand in the different stages of tumor progression. In concomitance, tumor cells undergoing EMT actively interact with the surrounding tumor microenvironment (TME) constituted by cell components and extracellular matrix as well as cell secretome elements. As a result, the TME is in turn modulated by the EMT process toward an aggressive behavior. The current review presents the intrinsic and extrinsic modulators of EMT and their relationship with the TME, focusing on the non-cell-derived components, such as secreted metabolites, extracellular matrix, as well as extracellular vesicles. Moreover, we explore how these modulators can be suitable targets for anticancer therapy and personalized medicine.

MicroRNA‑590 inhibits migration, invasion and epithelial‑to‑mesenchymal transition of esophageal squamous cell carcinoma by targeting low‑density lipoprotein receptor‑related protein 6

MicroRNA-590 (miR-590) has been revealed as a tumor suppressor, while low-density lipoprotein receptor-related protein 6 (LRP6) is considered to act as a tumor promoter. However, their roles and underlying molecular regulatory mechanisms in esophageal squamous cell carcinoma (ESCC) have yet to be fully elucidated. Therefore, the present study aimed to investigate these mechanisms. The expression levels of miR-590 and LRP6 in human ESCC samples and cell lines were determined using reverse transcription-quantitative PCR. Bioinformatics analysis was used to predict the relationship between miR-590 and LRP6, and luciferase assay was performed to validate the relationship between these factors. Transwell assays were used to determine cell migration and invasion, while western blotting assays were used to detect the protein expression levels of LRP6, E-cadherin, N-cadherin and Vimentin. The present study demonstrated that miR-590 was downregulated and LRP6 was upregulated in ESCC tissues and cell lines. Furthermore, it was found that miR-590 overexpression and LRP6 knockdown inhibited cell migration, invasion and epithelial-to-mesenchymal transition (EMT) in ESCC cell lines. Additional mechanistic studies identified that LRP6 was a target of, and was inhibited by, miR-590. Collectively, the present findings suggested that miR-590 inhibited the invasion, migration and EMT of ESCC cells by mediating LRP6.

Reduced Expression of METTL3 Promotes Metastasis of Triple-Negative Breast Cancer by m6A Methylation-Mediated COL3A1 Up-Regulation

The abnormal m6A modification caused by m6A modulators is a common feature of various tumors; however, little is known about which m6A modulator plays the most important role in triple-negative breast cancer (TNBC). In this study, when analyzing the influence of m6A modulators (METTL3, METTL14, WTAP, FTO, and ALKBH5) on the prognosis of breast cancer, especially in TNBC using several on-line databases, methyltransferase-like 3 (METTL3) was found to have low expression in breast cancer, and was closely associated with short-distance-metastasis-free survival in TNBC. Further investigation showed that knockdown of METTL3 could enhance the ability of migration, invasion, and adhesion by decreasing m6A level in TNBC cell lines. Collagen type III alpha 1 chain (COL3A1) was identified and verified as a target gene of METTL3. METTL3 could down-regulate the expression of COL3A1 by increasing its m6A methylation, ultimately inhibiting the metastasis of TNBC cells. Finally, with immunohistochemistry staining in breast cancer tissues, it was proved that METTL3 expression was negatively correlated with COL3A1 in TNBC, but not in non-TNBC. This study demonstrated the potential mechanism of m6A modification in metastasis and provided potential targets for treatment in TNBC.

Cell Derived Matrix Fibulin-1 Associates With Epidermal Growth Factor Receptor to Inhibit Its Activation, Localization and Function in Lung Cancer Calu-1 Cells

Epidermal Growth Factor Receptor (EGFR) is a known promoter of tumor progression and is overexpressed in lung cancers. Growth factor receptors (including EGFR) are known to interact with extracellular matrix (ECM) proteins, which regulate their activation and function. Fibulin-1 (FBLN1) is a major component of the ECM in lung tissue, and its levels are known to be downregulated in non-small cell lung cancers (NSCLC). To test the possible role FBLN1 isoforms could have in regulating EGFR signaling and function in lung cancer, we performed siRNA mediated knockdown of FBLN1C and FBLN1D in NSCLC Calu-1 cells. Their loss significantly increased basal (with serum) and EGF (Epidermal Growth Factor) mediated EGFR activation without affecting net EGFR levels. Overexpression of FBLN1C and FBLN1D also inhibits EGFR activation confirming their regulatory crosstalk. Loss of FBLN1C and FBLN1D promotes EGFR-dependent cell migration, inhibited upon Erlotinib treatment. Mechanistically, both FBLN1 isoforms interact with EGFR, their association not dependent on its activation. Notably, cell-derived matrix (CDM) enriched FBLN1 binds EGFR. Calu-1 cells plated on CDM derived from FBLN1C and FBLN1D knockdown cells show a significant increase in EGF mediated EGFR activation. This promotes cell adhesion and spreading with active EGFR enriched at membrane ruffles. Both adhesion and spreading on CDMs is significantly reduced by Erlotinib treatment. Together, these findings show FBLN1C/1D, as part of the ECM, can bind and regulate EGFR activation and function in NSCLC Calu-1 cells. They further highlight the role tumor ECM composition could have in influencing EGFR dependent lung cancers.

Functional Significance of Mirna-149 in Lung Cancer: Can it be Utilized as a Potential Biomarker or a Therapeutic Target?

Accumulating evidence has documented the significance of miR-149 as a promising tumor-suppressive non-coding RNA that play critical roles in regulating genes involved in cancer growth and metastasis. Notably, the ability of miR-149 to be utilized as a potential biomarker in the diagnosis/prognosis or a therapeutic target has also been explored using various cellular and preclinical models, as well as in clinical settings of lung cancer. While the applicability of miR-149 in assessing tumor progression has been suggested, its potential in predicting treatment outcomes is needed to be verified in diverse settings of lung cancer patients. The current review presents an overview of the functional significance of miR-149 with ongoing challenges in non-small cell lung cancer.

Bioengineered Tumor Organoids

Recent advances in biofabrication technologies, such as cell culture systems, and biomaterials have led to the development of three-dimensional (3D) cell culture platforms, such as tumor organoids. Tumor organoids are more physiologically accurate to the in vivo system, which they are intended to model, compared with traditional 2D cancer cell culture systems. Tumor organoids can mimic pathological and physical characteristics of tumors as well as maintain genetic stability of the cancer cells. Furthermore tumor organoids have advantage over animal models, being made from human cells and easily controlled in the laboratory to attain the desired tissue characteristics. In this section, we describe general tumor organoid technologies, the importance of the tumor microenvironment (TME) in model culture systems, and the use of tumor organoids in drug development and precision medicine. Organoid technologies continue to develop rapidly for applications in academic, clinical, and pharmaceutical settings.

Propofol Reduces Epithelial to Mesenchymal Transition, Invasion and Migration of Gastric Cancer Cells through the MicroRNA-195-5p/Snail Axis

BACKGROUND Gastric cancer (GC) is a life-threating malignancy worldwide. Accumulating studies suggest propofol has anti-tumor functions in addition to the anesthetic effect. This study aimed to figure out the effects of propofol treatment in GC development. MATERIAL AND METHODS Human GC SGC-7901 and NCI-N87 cells were treated with different doses of propofol. Then the invasion and migration of GC cells was measured. SGC-7901 cells following 10 μM propofol treatment were applied in the following experiments. MicroRNAs (miRNAs) with differential expression in cells with or without propofol treatment were analyzed. Expression of miR-195-5p, Snail, vimentin and E-cadherin in SGC-7901 cells was measured, and then loss-of-function of miR-195-5p and gain-of-function of Snail were performed. Target relation between miR-195-5p and Snail was confirmed using luciferase assay. Xenograft tumor was induced in nude mice to identify the effect of propofol on GC in vivo. RESULTS Propofol reduced epithelial to mesenchymal transition (EMT), invasion and migration of GC cells in a dose-dependent manner. Propofol elevated miR-195-5p expression but reduced Snail expression, and it reduced vimentin but increased E-cadherin expression in SGC-7901 cells. miR-195-5p directly bound to Snail. miR-195-5p inhibition or Snail promotion reversed propofol-inhibited malignant behaviors of SGC-7901 cells. In vitro results were reproduced in in vivo experiments. CONCLUSIONS Our study found that propofol could inhibit EMT, invasion, and migration of GC cells by promoting miR-195-5p expression and suppressing Snail expression. This study may provide novel insights in GC treatment.

Screening and identification of epithelial-to-mesenchymal transition-related circRNA and miRNA in prostate cancer

Epithelial-to-mesenchymal transition (EMT) plays a vital role in the progression and metastasis of prostate cancer. However, the molecular mechanisms underlying prostate cancer metastasis are not fully demonstrated. In this study, EMT was induced by interferon-γ (IFN-γ) in PC-3M IE8 cells. High-throughput sequencing was used to screen the differentially expressed circular RNAs (circRNAs) and miRNAs in the cells with or without IFN-γ treatment. EMT-related circRNAs and miRNAs were further identified by quantitative real-time PCR (qPCR). In addition, the relationships among circRNAs, miRNAs, and mRNA were predicted. After cells were treated with IFN-γ, western blot analysis was conducted to detect the expression levels of EMT markers. E-cadherin expression levels were found to be downregulated, and Twist expression levels were found to be upregulated. Our results also found that IFN-γ promoted PC-3M IE8 cell migration and invasion, indicating that IFN-γ could induce EMT in PC-3M IE8 cells. Furthermore, high-throughput sequencing results revealed 827 upregulated and 1279 downregulated circRNAs and 39 upregulated and 2076 downregulated miRNAs in the IFN-γ group compared with the control group. KEGG analysis showed that both differentially expressed circRNAs and differentially expressed miRNAs were enriched in the MAPK signaling pathway related to EMT. Furthermore, the qPCR results revealed that the expression of hsa_circ_0001085, hsa_circ_0004916, hsa_circ_0001165, hsa-miR-196b-5p, and hsa-miR-187-3p in the IFN-γ group was consistent with the sequencing results. hsa_circ_0001165 and hsa_circ_0001085 were used to construct the network of circRNA-miRNA-mRNA. It was found that hsa_circ_0001165 may regulate TNF expression through hsa-miR-187-3p to induce EMT in prostate cancer cells. In addition, hsa_circ_0001085 may indirectly regulate the PI3K-Akt signaling and TGF-β signaling pathways through hsa-miR-196b-5p and the MAPK signaling pathway through has-miR-451a, which played a regulatory role in prostate cancer cells in the EMT induction model. The results obtained in this study lay the foundation for future study.

Clinical Implications of Extracellular HMGA1 in Breast Cancer

The unconventional secretion of proteins is generally caused by cellular stress. During the tumorigenesis, tumor cells experience high levels of stress, and the secretion of some theoretically intracellular proteins is activated. Once in the extracellular space, these proteins play different paracrine and autocrine roles and could represent a vulnerability of cancer. One of these proteins is the high mobility group A1 (HMGA1), which is frequently overexpressed in tumors and presents a low expression in normal adult tissues. We have recently described that HMGA1 establishes an autocrine loop in invasive triple-negative breast cancer (TNBC) cells. The secretion of HMGA1 and its binding to the receptor for advanced glycation end products (RAGE) mediates the migration, invasion, and metastasis of TNBC cells and predicts the onset of metastasis in these patients. In this review, we summarized different strategies to exploit the novel tumorigenic phenotype mediated by extracellular HMGA1. We envisioned future clinical applications where the association between its change in subcellular localization and breast cancer progression could be used to predict tumor aggressiveness and guide treatment decisions. Furthermore, we proposed that targeting extracellular HMGA1 as monotherapy using monoclonal antibodies, or in combination with chemotherapy and other targeted therapies, could bring new therapeutic options for TNBC patients.

Stem-Like Cancer Cells in a Dynamic 3D Culture System: A Model to Study Metastatic Cell Adhesion and Anti-Cancer Drugs

Metastatic spread is mainly sustained by cancer stem cells (CSC), a subpopulation of cancer cells that displays stemness features. CSC are thought to be derived from cancer cells that undergo epithelial to mesenchymal transition (EMT), thus acquiring resistance to anoikis and anti-cancer drugs. After detachment from the primary tumor mass, CSC reach the blood and lymphatic flow, and disseminate to the target tissue. This process is by nature dynamic and in vitro models are quite far from the in vivo situation. In this study, we have tried to reproduce the adhesion process of CSC to a target tissue by using a 3D dynamic cell culture system. We isolated two populations of 3D tumor spheroids displaying CSC-like features from breast carcinoma (MCF-7) and lung carcinoma (A549) cell lines. Human fibroblasts were layered on a polystyrene scaffold placed in a dynamically perfused millifluidic system and then the adhesion of tumor cell derived from spheroids to fibroblasts was investigated under continuous perfusion. After 24 h of perfusion, we found that spheroid cells tightly adhered to fibroblasts layered on the scaffold, as assessed by a scanning electron microscope (SEM). To further investigate mechanisms involved in spheroid cell adhesion to fibroblasts, we tested the effect of three RGD integrin antagonists with different molecular structures on cell adhesion; when injected into the circuit, only cilengitide was able to inhibit cell adhesion to fibroblasts. Although our model needs further refinements and improvements, we do believe this study could represent a promising approach in improving current models to study metastatic infiltration in vitro and a new tool to screen new potential anti-metastatic molecules.