Brucine Suppresses Vasculogenic Mimicry in Human Triple-Negative Breast Cancer Cell Line MDA-MB-231

The in vitro dynamics of pseudo-vascular network formation

BACKGROUND/OBJECTIVES

Pseudo-vascular network formation in vitro is considered a key characteristic of vasculogenic mimicry. While many cancer cell lines form pseudo-vascular networks, little is known about the spatiotemporal dynamics of these formations.

METHODS

Here, we present a framework for monitoring and characterising the dynamic formation and dissolution of pseudo-vascular networks in vitro. The framework combines time-resolved optical microscopy with open-source image analysis for network feature extraction and statistical modelling. The framework is demonstrated by comparing diverse cancer cell lines associated with vasculogenic mimicry, then in detecting response to drug compounds proposed to affect formation of vasculogenic mimics. Dynamic datasets collected were analysed morphometrically and a descriptive statistical analysis model was developed in order to measure stability and dissimilarity characteristics of the pseudo-vascular networks formed.

RESULTS

Melanoma cells formed the most stable pseudo-vascular networks and were selected to evaluate the response of their pseudo-vascular networks to treatment with axitinib, brucine and tivantinib. Tivantinib has been found to inhibit the formation of the pseudo-vascular networks more effectively, even in dose an order of magnitude less than the two other agents.

CONCLUSIONS

Our framework is shown to enable quantitative analysis of both the capacity for network formation, linked vasculogenic mimicry, as well as dynamic responses to treatment.

Induction of ferroptosis by brucine suppresses gastric cancer progression through the p53-mediated SLCA711/ALOX12 axis

Increasing evidence indicates important antiproliferative and anti-inflammatory roles of brucine in various diseases. However, the mechanism through which brucine causes the cell death of gastric cancer (GC) remains unclear. In the current research, we looked into whether brucine inhibits GC progression. GC cell migration and proliferation were assessed in response to brucine using Transwell, scratch, and the Cell Counting Kit-8 (CCK-8) assays. To assess the expression of proteins linked to ferroptosis, western blotting was used. An in vivo experiment was conducted to investigate if brucine decreases tumor growth. The CCK-8 experiment demonstrated that brucine reduced AGS and MKN45 cell viability in a way that was dose- and time-dependent. Brucine dramatically promoted cell death in AGS and MKN45 cells according to flow cytometry. In addition, brucine reduced AGS and MKN45 cells' ability to migrate. According to Western blot investigations, brucine elevated p53 and ALOX12 expression, while suppressing the expression of SLC7A11 in AGS and MKN45 cells. Notably, silencing p53 reversed brucine-induced ferroptotic cell death. Additionally, brucine was shown to decrease tumor weight and volume in in vivo experiments. Moreover, malondialdehyde (MDA) and Fe2+ levels decreased in response to brucine treatment. Furthermore, in tumors treated with brucine, p53 and ALOX12 expression increased, whereas SLCA711 expression decreased. In summary, we demonstrated that brucine regulates the p53/SLCA711/ALOX12 axis to cause ferroptosis in GC cells. The results of this study lend support to the idea of treating GC with brucine.

Unveiling the experimental proof of the anticancer potential of ginsenoside Rg3 (Review)

Ginsenoside Rg3 (GS-Rg3), a sterol molecule isolated from ginseng, has demonstrated various immunological properties, including inhibition of cancer cell proliferation and metastasis, reversal of drug resistance and enhancement of chemotherapy sensitivity. The recent surge in attention towards GS-Rg3 can be attributed to its potential as an antitumor angiogenesis agent and as a therapeutic candidate for immunotherapy. The development of GS-Rg3 as an agent for these purposes has accelerated research on its mechanisms of action. The present review summarizes recent studies investigating the antitumor activity of GS-Rg3 and its underlying mechanisms, as well as providing essential information for future studies on GS-Rg3.

Mechanisms of angiogenesis in tumour

Angiogenesis is essential for tumour growth and metastasis. Antiangiogenic factor-targeting drugs have been approved as first line agents in a variety of oncology treatments. Clinical drugs frequently target the VEGF signalling pathway during sprouting angiogenesis. Accumulating evidence suggests that tumours can evade antiangiogenic therapy through other angiogenesis mechanisms in addition to the vascular sprouting mechanism involving endothelial cells. These mechanisms include (1) sprouting angiogenesis, (2) vasculogenic mimicry, (3) vessel intussusception, (4) vascular co-option, (5) cancer stem cell-derived angiogenesis, and (6) bone marrow-derived angiogenesis. Other non-sprouting angiogenic mechanisms are not entirely dependent on the VEGF signalling pathway. In clinical practice, the conversion of vascular mechanisms is closely related to the enhancement of tumour drug resistance, which often leads to clinical treatment failure. This article summarizes recent studies on six processes of tumour angiogenesis and provides suggestions for developing more effective techniques to improve the efficacy of antiangiogenic treatment.

Systematic pharmacology-based strategy to explore the mechanism of Semen Strychni for treatment of papillary thyroid carcinoma

The aim of the study was to investigated the mechanism of Strychnos nux-vomica L. (Semen Strychni, SS) against papillary carcinoma thyroid (PTC) by combined of network pharmacology and experimental verification. By searching the TCMSP, SEA and SwissTarget Prediction database, the main active ingredients and related targets were obtained. Utilizing Venny 2.1.0 String database and Cytoscape 3.7.2 to screened the intersection target and constructed protein-protein interaction (PPI) network diagram. Using R 4.0.4 software carried out the enrichment analysis of GO and KEGG. HPLC was carried out using LC-20A modular HPLC system to identify the bioactive compound brucine present in SS. Molecular docking was performed using Discovery 2019 software. The inhibition rate was detected by CCK8 method. Western blot was used to detect the expression levels of brucine anti-PTC related pathway proteins. 14 active components were screened out, of which 4 main components showed tight relationship with PTC. SS may play the anti-PTC role by acting on two main pathways (TNF signaling pathway and MAPK signaling pathway) and mediating various biological functions. HPLC analysis revealed that brucine was a suitable marker for standardization of the SS. 4 active components exhibit strong binding energy with core protein. Brucine could significantly reduce the activity of BCPAP cells compared with isobrucine, stigmasterol, (+)-catechin. Brucine may reduce the protein expression levels of IL-6, VEGFA, JUN, TP53, 1L1B, PTGS2, BCL2, CASP3, CASP8, and CASP9 while increase the protein expression levels of BAD, cleaved-CASP3, cleaved-CASP8, and cleaved-CASP9 in BCPAP cells, respectively. The active components of SS against PTC mainly include isobrucine, stigmasterol, (+)-catechin, brucine. Among them, brucine exhibits the strongest anti-PTC activity in BCPAP cells, which may reduce the PTC-related protein expression levels. Therefore, SS may exhibits the anti-PTC activities through multiple targets and pathways.

Advance in vasculogenic mimicry in ovarian cancer (Review)

Ovarian cancer (OC) is a common and highly prevalent malignant tumor in women, associated with a high mortality rate, easy recurrence and easy metastasis, which is predominantly at an advanced stage when detected in patients. This renders the cancer more difficult to treat, and consequently it is also associated with a low survival rate, being the malignancy with the highest mortality rate among the various gynecological tumors. As an important factor affecting the development and metastasis of OC, understanding the underlying mechanism(s) through which it is formed and developed is crucial in terms of its treatment. At present, the therapeutic methods of angiogenic mimicry for OC remain in the preliminary stages of exploration and have not been applied in actual clinical practice. In the present review, various signaling pathways and factors affecting angiogenic mimicry in OC were described, and the chemical synthetic drugs, natural compound extracts, small-molecule protein antibodies and their associated targets, and so on, that target angiogenic mimicry in the treatment of OC, were discussed. The purpose of this review was to provide new research ideas and potential theoretical support for the discovery of novel therapeutic targets for OC that may be applied in the clinic, with the aim of effectively reducing its metastasis and recurrence rates.

Brucine suppresses proliferation and promotes apoptosis of human cholangiacarcinoma cells via the inhibition of COX2 expression

Aims The aim of this study was to investigate the anti-tumor efficacy of brucine on intrahepatic cholangiocarcinoma (ICC). Methods ICC QBC939 cells were treated with brucine, cell viability, cell cycle and apoptosis were analyzed using CCK-8 and flow cytometry. The expression of COX-2 and apoptosis related proteins Casp3, Bax and Bcl-2 were detected by Western blot analysis. QBC939 cells were subcutaneously transplanted into nude mice and the mice were injected with brucine intraperitoneally. The expression of Ki67, COX-2 and apoptosis related proteins were detected by immunohistochemical staining and Western blot analysis. Results Brucine significantly inhibited the proliferation and cell cycle progression while promoted the apoptosis of QBC939 cells. The expression of the apoptotic proteins Casp3 and Bax was upregulated, while the expression of Bcl-2 and COX-2 was downregulated in QBC939 cells with brucine treatment. Moreover, the overexpression of COX-2 could antagonize the effects of brucine on QBC939 cells. In vivo, brucine inhibited subcutaneous tumor formation in nude mice, and the expression of Ki67, COX-2 and Bcl-2 decreased while the expression of Casp3 and Bax increased in tumor tissues from nude mice with brucine treatment. Conclusions Brucine can significantly inhibit the progression of cholangiocarcinoma in vitro and in vivo, and the mechanism may be related to the inhibition of COX-2 expression.

Clinicopathological significance of vasculogenic mimicry and fetal hemoglobin expression in peripheral neuroblastic tumors in children

PURPOSE

Vasculogenic mimicry (VM) is present in a variety of malignant tumors, and is related to the degree of malignancy. Neuroblastoma (NB) can induce the expression of fetal hemoglobin (HB-F). The purpose of this study was to investigate the clinicopathological significance of the number of VMs and tumor cell expression of HB-F in children with peripheral neuroblastic tumors (pNTs).

MATERIALS AND METHODS

We collected tissue samples and clinical data from 101 children with pNTs; prepared serial sections of tissue wax blocks for hematoxylin and eosin staining, CD31/periodic acid-Schiff double staining, and HB-F immunohistochemical staining; and analyzed the experimental results.

RESULTS

There were significant differences in the number of VMs and HB-F expression in tumor cells according to the pathological classification of pNTs (P<0.001, collectively). Poorly differentiated NB had a median of 137 VMs and 25.5% HB-F expression. Differentiating NB had a median of 90.5 VMs and 8.5% HB-F expression. Ganglioneuroblastoma intermixed had a median of 6.0 VMs and 1.0% HB-F expression. Ganglioneuromas had no VM and a median of 0% HB-F expression. The number of VMs and the expression of HB-F were significantly higher in the poor prognosis group than the good prognosis group (P<0.001, collectively). There was a strong positive correlation between the number of VMs and HB-F expression in pNTs (r=0.891, P<0.001).

CONCLUSION

We confirmed VM and HB-F expression in pNTs. The number of VMs and HB-F expression were higher in poorly differentiated tumors. The number of VMs and level of HB-F expression in pNTs might be related to the prognosis.

Exploring Amodiaquine's Repurposing Potential in Breast Cancer Treatment-Assessment of In-Vitro Efficacy & Mechanism of Action

Due to the heterogeneity of breast cancer, current available treatment options are moderately effective at best. Hence, it is highly recommended to comprehend different subtypes, understand pathogenic mechanisms involved, and develop treatment modalities. The repurposing of an old FDA approved anti-malarial drug, amodiaquine (AQ) presents an outstanding opportunity to explore its efficacy in treating majority of breast cancer subtypes. Cytotoxicity, scratch assay, vasculogenic mimicry study, and clonogenic assay were employed to determine AQ's ability to inhibit cell viability, cell migration, vascular formation, and colony growth. 3D Spheroid cell culture studies were performed to identify tumor growth inhibition potential of AQ in MCF-7 and MDAMB-231 cell lines. Apoptosis assays, cell cycle analysis, RT-qPCR assays, and Western blot studies were performed to determine AQ's ability to induce apoptosis, cell cycle changes, gene expression changes, and induction of autophagy marker proteins. The results from in-vitro studies confirmed the potential of AQ as an anti-cancer drug. In different breast cancer cell lines tested, AQ significantly induces cytotoxicity, inhibit colony formation, inhibit cell migration, reduces 3D spheroid volume, induces apoptosis, blocks cell cycle progression, inhibit expression of cancer related genes, and induces LC3BII protein to inhibit autophagy. Our results demonstrate that amodiaquine is a promising drug to repurpose for breast cancer treatment, which needs numerous efforts from further studies.

Small Molecule Compounds of Natural Origin Target Cellular Receptors to Inhibit Cancer Development and Progression

Receptors are macromolecules that transmit information regulating cell proliferation, differentiation, migration and apoptosis, play key roles in oncogenic processes and correlate with the prognoses of cancer patients. Thus, targeting receptors to constrain cancer development and progression has gained widespread interest. Small molecule compounds of natural origin have been widely used as drugs or adjuvant chemotherapeutic agents in cancer therapies due to their activities of selectively killing cancer cells, alleviating drug resistance and mitigating side effects. Meanwhile, many natural compounds, including those targeting receptors, are still under laboratory investigation for their anti-cancer activities and mechanisms. In this review, we classify the receptors by their structures and functions, illustrate the natural compounds targeting these receptors and discuss the mechanisms of their anti-cancer activities. We aim to provide primary knowledge of mechanistic regulation and clinical applications of cancer therapies through targeting deregulated receptors.

The development of tumour vascular networks

The growth of solid tumours relies on an ever-increasing supply of oxygen and nutrients that are delivered via vascular networks. Tumour vasculature includes endothelial cell lined angiogenesis and the less common cancer cell lined vasculogenic mimicry (VM). To study and compare the development of vascular networks formed during angiogenesis and VM (represented here by breast cancer and pancreatic cancer cell lines) a number of in vitro assays were utilised. From live cell imaging, we performed a large-scale automated extraction of network parameters and identified properties not previously reported. We show that for both angiogenesis and VM, the characteristic network path length reduces over time; however, only endothelial cells increase network clustering coefficients thus maintaining small-world network properties as they develop. When compared to angiogenesis, the VM network efficiency is improved by decreasing the number of edges and vertices, and also by increasing edge length. Furthermore, our results demonstrate that angiogenic and VM networks appear to display similar properties to road traffic networks and are also subject to the well-known Braess paradox. This quantitative measurement framework opens up new avenues to potentially evaluate the impact of anti-cancer drugs and anti-vascular therapies.

Fouladzadeh, Dorraki and colleagues investigate the development of angiogenic networks for in vitro cancer cell lines. They demonstrate that during the growth stages of vasculogenic mimicry, the number of edges and vertices decreases but the edge length increases resulting in improved network efficiency.

Bioinformatics, Molecular Docking and Experiments In Vitro Analyze the Prognostic Value of CXC Chemokines in Breast Cancer

The increasing incidence and mortality rate of Breast cancer (BC) make it a major public health problem around the world. CXC chemokines can mediate the migration of immune cells and regulate apoptosis in tumor. However, the expression and prognostic value of them in BC and their targeted drugs have not been clarified. Therefore, in this study, ONCOMINE, GEPIA2.0, UALCAN, Venny2.1.0, cBioPortal, STRING, Gene MANIA, Pathway Commons, DAVID6.8, Omicshare, Cytoscape3.6.1, TIMER2.0, Drug Bank, TCMSP, RSCBPDB, PubChem, pkCSM, Chem Draw, AutoDockTools-1.5.6 and PyMOL were utilized for analysis. The expression of CXCL1-3, CXCL9-13 between BC and normal tissues was significantly different in all the three databases. And the expression of CXCL1-2, CXCL12-13 was correlated with the stages of BC. But only CXCL1-3 were prone to mutation, and negatively correlated with survival and prognosis of BC patients. Taken together, CXCL1-2 might be therapeutic targets and biomarkers for BC patients. In addition, both of them were associated with immune infiltration. The results of molecular docking showed that Quercetin was most likely to be developed as drugs that interacted directly with CXCL1-2. And GLU29 of CXCL1, ASP-1, PRO-96, TRP-47 and LEU-45 of CXCL2 were the most potential sites, which provided valuable reference for further study of pharmacodynamics and mechanism. In addition, the inhibitory effect of Quercetin on proliferation and promoting apoptosis of BC related cell lines were confirmed in vitro. Western blot and Real-Time PCR confirmed that it increased the expression of CXCL1-2 in MDA-MB-231 and MCF-7 cells.

Date Palm Extract (Phoenix dactylifera) PEGylated Nanoemulsion: Development, Optimization and Cytotoxicity Evaluation

Date palm fruit (Phoenix dactylifera) is reputed to have numerous biological activities, including anticancer properties. To utilize the great fortune of this fruit, the current study aimed to maximize its pharmacological activity. Date palm extract (DPE) of Khalas cultivar was obtained in powder form and then was formulated into nanoemulsion (NE). The optimized DPE-NE was formulated along with its naked counterpart followed by studying their physical and chemical properties. A qualitative assessment of total serum protein associated with the surface of formulations was implemented. Studies for the in vitro release of DPE from developed NE before and after incubation with serum were investigated. Eventually, an MTT assay was conducted. Total phenolic and flavonoid contents were 22.89 ± 0.013 mg GAE/g of dry DPE and 9.90 ± 0.03 mg QE/g of dry DPE, respectively. Homogenous NE formulations were attained with appropriate particle size and viscosity that could be administered intravenously. The optimized PEGylated NE exhibited a proper particle size, PDI, and zeta potential. Total serum protein adsorbed on PEG-NE surface was significantly low. The release of the drug through in vitro study was effectively extended for 24 h. Ultimately; PEGylated NE of DPE attained significant inhibition for cancer cell viability with IC₅₀ values of 18.6 ± 2.4 and 13.5 ± 1.8 µg/mL for MCF-7 and HepG2 cell lines, respectively. PEGylated NE of DPE of Khalas cultivar will open the gate for future adjuvants for cancer therapy.

COE Inhibits Vasculogenic Mimicry by Targeting EphA2 in Hepatocellular Carcinoma, a Research Based on Proteomics Analysis

New strategies and drugs are urgently needed to improve the treatment of hepatocellular carcinoma (HCC). Vasculogenic mimicry (VM) has been elucidated being associated with the progression of HCC and anti-VM could be a promising strategy. Celastrus orbiculatus extract (COE), a mixture of 26 compounds isolated from the Chinese Herb Celastrus Orbiculatus Vine, has been elucidated to be able to disrupt VM formation in HCC. This study aims to dissect and identify the potential targets of COE on anti-VM formation both in vitro and in vivo that are distinct from our previous study. Proteomics analysis was used to identify differential proteins in HCC cells treated with or without COE (Data are available via ProteomeXchange with identifier PXD022203). Cells invasion was examined using Transwell. Matrigel was used to establish a 3-D culture condition for VM formation in vitro. RT-PCR and Western Blot were used to examine changes of mRNA and protein respectively. Clinical resected samples were applied to confirm association between VM formation and identified targets. Subcutaneous xenograft tumor model was established to observe tumor growth and VM formation in vivo. PAS-CD34 dual staining was used to detect VM in vivo. A total of 194 proteins were identified to be differentially expressed in HCC cells treated with or without COE. In the 93 down-regulated proteins EphA2 stood out to be regulated on both RNA and protein level. Disruption EphA2 using COE or NVP inhibited VM formation and decreased VM associated biomarkers. In xenograft mouse model, COE inhibited tumor growth and VM formation via down-regulating EphA2. Taken together, our results indicate that COE could be used in HCC treatment because of its promising anti-VM effect.

Vasculogenic mimicry, a negative indicator for progression free survival of lung adenocarcinoma irrespective of first line treatment and epithelial growth factor receptor mutation status

Background

Vascular mimicry (VM) was associated with the prognosis of cancers. The aim of the study was to explore the association between VM and anticancer therapy response in patients with lung adenocarcinoma.

Methods

This was a single-center retrospective study of patients with lung adenocarcinoma between March 1st, 2013, to April 1st, 2019, at the Second People’s Hospital of Taizhou City. All included patients were divided into the VM and no-VM groups according to whether VM was observed or not in the specimen. Vessels with positive PAS and negative CD34 staining were confirmed as VM. The main outcome was progression-free survival (PFS).

Results

Sixty-six (50.4%) patients were male. Eighty-one patients received chemotherapy as the first-line treatment, and 50 patients received TKIs. Forty-five (34.4%) patients were confirmed with VM. There was no difference regarding the first-line treatment between the VM and no-VM groups (P = 0.285). The 86 patients without VM had a median PFS of 279 (range, 90–1095) days, and 45 patients with VM had a median PFS of 167 (range, 90–369) days (P < 0.001). T stage (hazard ratio (HR) = 1.37, 95% confidence interval (CI): 1.10–1.71), N stage (HR = 1.43, 95%CI: 1.09–1.86), M stage (HR = 2.85, 95%CI: 1.76–4.61), differentiation (HR = 1.85, 95%CI: 1.29–2.65), therapy (HR = 0.32, 95%CI: 0.21–0.49), VM (HR = 2.12, 95%CI: 1.33–3.37), and ECOG (HR = 1.41, 95%CI: 1.09–1.84) were independently associated with PFS.

Conclusion

The benefits of first-line TKIs for NSCLC with EGFR mutation are possibly better than those of platinum-based regimens in patients without VM, but there is no difference in the benefit of chemotherapy or target therapy for VM-positive NSCLC harboring EGFR mutations.

Establishment and Characterization of Canine Mammary Gland Carcinoma Cell Lines With Vasculogenic Mimicry Ability in vitro and in vivo

Mammary tumors affect intact and elderly female dogs, and almost 50% of these cases are malignant. Cell culture offers a promising preclinical model to study this disease and creates the opportunity to deposit cell lines at a cell bank to allow greater assay reproducibility and more reliable validation of the results. Another important aspect is the possibility of establishing models and improving our understanding of tumor characteristics, such as vasculogenic mimicry. Because of the importance of cancer cell lines in preclinical models, the present study established and characterized primary cell lines from canine mammary gland tumors. Cell cultures were evaluated for morphology, phenotype, vasculogenic mimicry (VM), and tumorigenicity abilities. We collected 17 primary mammary carcinoma and three metastases and obtained satisfactory results from 10 samples. The cells were transplanted to a xenograft model. All cell lines exhibited a spindle-shaped or polygonal morphology and expressed concomitant pancytokeratin and cytokeratin 8/18. Four cell lines had vasculogenic mimicry ability in vitro, and two cell lines showed in vivo tumorigenicity and VM in the xenotransplanted tumor. Cellular characterization will help create a database to increase our knowledge of mammary carcinomas in dogs, including studies of tumor behavior and the identification of new therapeutic targets.

Vascular mimicry: changing the therapeutic paradigms in cancer

Cancer is a major problem in the health system, and despite many efforts to effectively treat it, none has yet been fully successful. Angiogenesis and metastasis are considered as major challenges in the treatment of various cancers. Researchers have struggled to succeed with anti-angiogenesis drugs for the effective treatment of cancer, although new challenges have emerged in the treatment with the emergence of resistance to anti-angiogenesis and anti-metastatic drugs. Numerous studies have shown that different cancers can resist anti-angiogenesis drugs in a new process called vascular mimicry (VM). The studies have revealed that cells resistant to anti-angiogenesis cancer therapies are more capable of forming VMs in the in vivo and in vitro environment, although there is a link between the presence of VM and poor clinical outcomes. Given the importance of the VM in the challenges facing cancer treatment, researchers are trying to identify factors that prevent the formation of these structures. In this review article, it is attempted to provide a comprehensive overview of the molecules and main signaling pathways involved in VM phenomena, as well as the agents currently being identified as anti-VM and the role of VM in response to treatment and prognosis of cancer patients.

Brucine: A Review of Phytochemistry, Pharmacology, and Toxicology

Brucine, a weak alkaline indole alkaloid, is one of the main bioactive and toxic constituents of Nux-vomica. Modern pharmacology studies and clinical practice demonstrate that brucine possesses wide pharmacological activities, such as anti-tumor, anti-inflammatory, analgesic, and the effects on cardiovascular system and nervous system, etc. However, its central nervous system toxicity severely limits its clinical application. Herein, the physicochemical properties, pharmacological activities, and toxicity of brucine were reviewed, and the novel strategies to address the toxicity issues were discussed, aiming to bring new insights into further research and application of this active component.

Vasculogenic mimicry in carcinogenesis and clinical applications

Distinct from classical tumor angiogenesis, vasculogenic mimicry (VM) provides a blood supply for tumor cells independent of endothelial cells. VM has two distinct types, namely tubular type and patterned matrix type. VM is associated with high tumor grade, tumor progression, invasion, metastasis, and poor prognosis in patients with malignant tumors. Herein, we discuss the recent studies on the role of VM in tumor progression and the diverse mechanisms and signaling pathways that regulate VM in tumors. Furthermore, we also summarize the latest findings of non-coding RNAs, such as lncRNAs and miRNAs in VM formation. In addition, we review application of molecular imaging technologies in detection of VM in malignant tumors. Increasing evidence suggests that VM is significantly associated with poor overall survival in patients with malignant tumors and could be a potential therapeutic target.

An Overview of Vasculogenic Mimicry in Breast Cancer

Vasculogenic mimicry (VM) is the formation of vascular channels lacking endothelial cells. These channels are lined by tumor cells with cancer stem cell features, positive for periodic acid-Schiff, and negative for CD31 staining. The term VM was introduced by Maniotis et al. (1), who reported this phenomenon in highly aggressive uveal melanomas; since then, VM has been associated with poor prognosis, tumor aggressiveness, metastasis, and drug resistance in several tumors, including breast cancer. It is proposed that VM and angiogenesis (the de novo formation of blood vessels from the established vasculature by endothelial cells, which is observed in several tumors) rely on some common mechanisms. Furthermore, it is also suggested that VM could constitute a means to circumvent anti-angiogenic treatment in cancer. Therefore, it is important to determinant the factors that dictate the onset of VM. In this review, we describe the current understanding of VM formation in breast cancer, including specific signaling pathways, and cancer stem cells. In addition, we discuss the clinical significance of VM in prognosis and new opportunities of VM as a target for breast cancer therapy.