Stem-like Human Breast Cancer Cells Initiate Vasculogenic Mimicry on Matrigel

Vasculogenic mimicry (VM), referring to vasculogenic structures lined by tumor cells, can be distinguished from angiogenesis, and is responsible for the aggressiveness and metastatic potential of tumors. HCC1937/p53 cells were derived from triple-negative breast cancer (TNBC), and used to investigate the roles of breast cancer stem cells (CSCs) in the formation of VM. HCC1937/p53 cells formed mesh-like structures on matrigel culture in which expression of VM-related genes, vascular endothelial (VE)-cadherin, matrix metalloproteinase (MMP)-2 and MMP-9 was confirmed by droplet digital polymerase chain reaction (PCR). In immunofluorescence microscopy, aldehyde dehydrogenase (ALDH)1A3⁺ cells with properties of CSCs or progenitors and GATA binding protein 3 (GATA3)⁺ cells with more differentiated characteristics were localized in the bridging region and aggregated region of VM structures, respectively. In fluorescence-activated cell sorting analysis, ALDH⁺ cells, considered to be a subpopulation of CSCs sorted by the aldefluor assay, exhibited marked VM formation on matrigel in 24 hr, whereas ALDH^- cells did not form VM, indicating possible roles of CSCs in VM formation. The stem-like cancer cells resistant to p53-induced apoptosis, which expressed a high rate of ALDH1A3 and Sex-determining region Y (SRY)-box binding protein-2 (Sox-2), completed VM formation much faster than the control. These findings may provide clues to elucidate the significance of VM formed by treatment-resistant CSCs in the metastatic potential and poor prognosis associated with TNBC.