Vasculogenic mimicry (VM) is an angiogenic-independent mechanism of blood vessel formation whereby aggressive tumor cells undergo formation of capillarylike structures. Thus, interventions aimed at angiogenesis might not target the entire tumor vasculature. A more holistic approach is therefore needed in the development of improved antivascular agents.Transgelin, an actin-binding protein, has been associated with multiple stages of cancer development such as proliferation, migration and invasion, but little is known about its role in vasculogenic mimicry. We present here, an additional mechanism by which transgelin promotes malignancy by way of its association with the occurrence of VM. Although transgelin knockdown did not affect the transcript levels of most of the angiogenesis-related genes in this study, it was associated with the inhibition of the uptake of IL-8, accompanied by suppressed VM, indicating that transgelin is required for VM. These observations are relevant to the future development of efficient antivascular agents.
AbstractVasculogenic mimicry (VM) is a non-classical mechanism recently described in many tumors, whereby cancer cells, rather than endothelial cells, form blood vessels. Transgelin is an actin-binding protein that has been implicated in multiple stages of cancer development. In this study, we investigated the role of transgelin in VM and assessed its effect on the expression of endothelial and angiogenesis-related genes during VM in MDA-MB-231 breast cancer cells. We confirmed the ability of MDA-MB-231 cells to undergo VM through a tube formation assay. Flow cytometry analysis revealed an increase in the expression of the endothelial-related markers VE-cadherin and CD34 in cells that underwent VM, compared with those growing in a monolayer, which was confirmed by immunocytochemistry. We employed siRNA to silence transgelin, and knockdown efficiency was determined by western blot analyses. Downregulation of transgelin suppressed cell proliferation and tube formation, but increased IL-8 levels in Matrigel cultures. RT-PCR analyses revealed that the expression of IL-8, VE-cadherin, and CD34 was unaffected by transgelin knockdown, indicating that increased IL-8 expression was not due to enhanced transcriptional activity. More importantly, the inhibition of IL-8/CXCR2 signaling also resulted in suppression of VM with increased IL-8 levels, confirming that increased IL-8 levels after transgelin knockdown was due to inhibition of IL-8 uptake. Our findings indicate that transgelin regulates VM by enhancing IL uptake. These observations are relevant to the future development of efficient antivascular agents.
The role of transgelin (TAGLN) in cancer has been discussed; however, the mechanisms underlying its regulation and correlation with MDA‐MB‐231 cell plasticity and migratory patterns remain unclear. We generated stable TAGLN‐knockdown MDA‐MB‐231 cells and treated them with phorbol 12‐myristate 13‐acetate or transforming growth factor (TGF)‐β. Chemotaxis, morphology, and invasion were assayed using three‐dimensional matrices to evaluate cytoskeletal remodeling and migratory changes. Wound healing assays were conducted using cell inserts. TAGLN knockdown cells exhibited altered morphology due to cytoskeletal remodeling, yet only untreated and TGFβ1‐treated cells exhibited enhanced migration. Untreated and TGFβ1‐treated TAGLN knockdown cells showed increased N‐WASP, ROCK1, and ROCK2 protein levels, which induce cytoskeletal remodeling. Evaluating phospholipase Cγ1 (PLCγ1)‐cofilin signaling‐related proteins revealed that only TGFβ1‐treated TAGLN knockdown cells were influenced by PLCγ1‐cofilin signaling. Taken together, TAGLN knockdown is necessary for the TGFβ1‐mediated activation of PLCγ1‐cofilin pathway‐driven amoeboid morphology and enhanced migratory properties in MDA‐MB‐231 cells.
Signaling between cancer cells, their neighboring cells, and mesenchymal stem cells (MSCs) forms the tumor microenvironment. The complex heterogeneity of this microenvironment varies depending on the tumor type and its origins. However, most of the existing cancer-based studies have focused on cancer cells. In this study, we used a direct co-culture system (cross-talk signaling) to induce cross-interaction between cancer cells and mesenchymal stem cells. This induced deformation of MSCs. MSCs showed a diminished ability to maintain homeostasis. In particular, increase in the invasion ability of MSCs by TGF-β1 and decrease in p53, which plays a key role in cancer development, is an important discovery. It can thus be deduced that blocking these changes can effectively inhibit metastatic colorectal cancer. In conclusion, understanding the interactions and changes in MSCs associated with cancer will help develop novel therapeutic strategies for cancer.
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