Molecular regulation of vasculogenic mimicry in human uveal melanoma cells: role of helix-loop-helix Id2 (inhibitor of DNA binding 2)

VEGF Induce Vasculogenic Mimicry of Choroidal Melanoma through the PI3k Signal Pathway

Purpose

To explore the effect of VEGF (vascular endothelial growth factor) on the vasculogenic mimicry (VM) formation of Choroidal Melanoma (CM) through PI3k signal pathway, to find novel targets for CM therapy.

Methods

This research investigated the molecular mechanism of VEGF promoting VM formation of CM. First, we evaluated the expressions of VEGF in 20 CM specimens by immunohistochemical determination. Then we detected expressions of VEGF, AKT, MT1-MMP, MMP2, and MMP9 of OCM-1 in hypoxia. siRNA was used to inhibit the expression of VEGF, to realize the control of the VM formation. The VM formation was evaluated through wound healing assay, transwell assay, and apoptosis. And then we testify the correlation of the VM and the factors in protein and mRNA level preliminarily.

Results

VEGF protein was expressed in CM in all 20 cases of CM, especially along the VM. In hypoxia, the expression of VEGF in OCM-1 increased significantly. VEGF gene deletion reduced the proliferation, migration, and invasion of OCM-1. VEGF gene deletion impaired the expression of invasive associated genes like VEGF, p-AKT, AKT, MT1-MMP, MMP2, and MMP9. These results indicate that VEGF induce VM formation in CM by activating PI3K/AKT signaling pathway.

Conclusions

VEGF promoted VM formation by the PI3K signal transduction pathway, indicating a molecular mechanism which may be used to develop new therapeutic targets for the clinical treatment of CM.

Uveal Melanoma, Angiogenesis and Immunotherapy, Is There Any Hope?

Uveal melanoma is considered a rare disease but it is the most common intraocular malignancy in adults. Local treatments are effective, but the systemic recurrence rate is unacceptably high. Moreover, once metastasis have developed the prognosis is poor, with a 5-year survival rate of less than 5%, and systemic therapies, including immunotherapy, have rendered poor results. The tumour biology is complex, but angiogenesis is a highly important pathway in these tumours. Vasculogenic mimicry, the ability of melanomas to generate vascular channels independently of endothelial cells, could play an important role, but no effective therapy targeting this process has been developed so far. Angiogenesis modulates the tumour microenvironment of melanomas, and a close interplay is established between them. Therefore, combining immune strategies with drugs targeting angiogenesis offers a new therapeutic paradigm. In preclinical studies, these approaches effectively target these tumours, and a phase I clinical study has shown encouraging results in cutaneous melanomas. In this review, we will discuss the importance of angiogenesis in uveal melanoma, with a special focus on vasculogenic mimicry, and describe the interplay between angiogenesis and the tumour microenvironment. In addition, we will suggest future therapeutic approaches based on these observations and mention ways in which to potentially enhance current treatments.

Rho Kinase Inhibitor Fasudil Suppresses the Vasculogenic Mimicry of B16 Mouse Melanoma Cells Both In Vitro and In Vivo

The aim of this study was to investigate the biologic role of the Rho kinase inhibitor fasudil in the vasculogenic mimicry (VM) of B16 mouse melanoma cells. It was previously reported that RhoA plays a critical role in angiogenesis by coordinating endothelial cell cytoskeleton remodeling and promoting endothelial cell motility. Although RhoA has been implicated in the regulation of angiogenesis, little has been described regarding its control of these tumor cell-lined channels. In this study, we established an in vitro model of VM using 3-dimensional cell culturing of mouse B16 melanoma cells and studied VM in vivo by transplanting B16 cells into C57/BL mice. Next, we explored the effect of RhoA and Rho-associated, coiled-coil containing protein kinase (ROCK) on VM formation using the Rho kinase inhibitor fasudil. We provide direct evidence that fasudil leads to reduced vascular-like channels in Matrigel. Additional experiments suggested that fasudil prevents both initial cellular architecture changes and cell migration in vitro. Finally, we provide in-depth evidence for the underlying mechanisms of fasudil-induced VM destruction using the Rho-GTPase agonist lysophosphatidic acid. In vivo studies revealed that fasudil reduced B16 melanoma cell xenograft tumor growth without causing significant toxicity in mice. Fasudil-treated tumors also displayed fewer VM channels. These results suggest that fasudil may be an emerging therapeutic option for targeting cancer VM.

Advanced research on vasculogenic mimicry in cancer

Vasculogenic mimicry (VM) is a brand-new tumour vascular paradigm independent of angiogenesis that describes the specific capacity of aggressive cancer cells to form vessel-like networks that provide adequate blood supply for tumour growth. A variety of molecule mechanisms and signal pathways participate in VM induction. Additionally, cancer stem cell and epithelial-mesenchymal transitions are also shown to be implicated in VM formation. As a unique perfusion way, VM is associated with tumour invasion, metastasis and poor cancer patient prognosis. Due to VM's important effects on tumour progression, more VM-related strategies are being utilized for anticancer treatment. Here, with regard to the above aspects, we make a review of advanced research on VM in cancer.

A meta-analysis of microarray-based gene expression studies of olfactory bulb-derived olfactory ensheathing cells

Genome wide transcriptional profiling and large scale proteomics have emerged as two powerful methods to dissect the molecular properties of specific neural tissues or cell types on a global scale. Several genome-wide transcriptional profiling and proteomics studies have been published on cultured olfactory ensheathing cells (OEC). In this article we present a meta-analysis of all five published and publicly available micro-array gene expression datasets of cultured early-passage-OB-OEC with other cell types (Schwann cells, late-passage-OB-OEC, mucosa-OEC, an OEC cell line, and acutely dissected OEC). The aim of this meta-analysis is to identify genes and molecular pathways that are found in multiple instead of one isolated study. 454 Genes were detected in at least three out of five microarray datasets. In this "Top-list", genes involved in the biological processes "growth of neurites", "blood vessel development", "migration of cells" and "immune response" were strongly overrepresented. By applying network analysis tools, molecular networks were constructed and Hub-genes were identified that may function as key genes in the above mentioned interrelated processes. We also identified 7 genes (ENTPD2, MATN2, CTSC, PTHLH, GLRX1, COL27A1 and ID2) with uniformly higher or lower expression in early-passage-OB-OEC in all five microarray comparisons. These genes have diverse but intriguing roles in neuroprotection, neurite extension and/or tissue repair. Our meta-analysis provides novel insights into the molecular basis of OB-OEC-mediated neural repair and can serve as a repository for investigators interested in the molecular biology of OEC. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

Molecular regulation of vasculogenic mimicry in tumors and potential tumor-target therapy

“Vasculogenic mimicry (VM)”, is a term that describes the unique ability of highly aggressive tumor cells to express a multipotent, stem cell-like phenotype, and form a pattern of vasculogenic-like networks in three-dimensional culture. As an angiogenesis-independent pathway, VM and/or periodic acid-schiff-positive patterns are associated with poor prognosis in tumor patients. Moreover, VM is resistant to angiogenesis inhibitors. Here, we will review the advances in research on biochemical and molecular signaling pathways of VM in tumors and on potential anti-VM therapy strategy.

Vasculogenic mimicry and microcirculation in tumors

Vasculogenic mimicry (VM), a term that describes a novel form of angiogenesis-independent microcirculation pattern recently found in few highly aggressive tumors, is formed by tumor cells, rather than endothelial cells. VM is closely correlated with the invasiveness, metastasis and prognosis of related tumors. The presence of VM is associated with an embryonic like phenotype acquired by tumor cells and the biological effects of many proteins. Furthermore, tumor microenvironment also plays an important role in the development of VM. Here, we will review the advances in research on the characteristic, formative mechanisms and clinical significance of VM.