Vasculogenic 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. Impact statement Vasculogenic mimicry (VM) is an angiogenic-independent mechanism of blood vessel formation whereby aggressive
tumor cells undergo formation of capillary-like 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.