Epithelial-to-endothelial transition and cancer stem cells: two cornerstones of vasculogenic mimicry in malignant tumors

Emerging Paradigms in Cancer Metastasis: Ghost Mitochondria, Vasculogenic Mimicry, and Polyploid Giant Cancer Cells

The capacity of cancer cells to migrate from a primary tumor, disseminate throughout the body, and eventually establish secondary tumors is a fundamental aspect of metastasis. A detailed understanding of the cellular and molecular mechanisms underpinning this multifaceted process would facilitate the rational development of therapies aimed at treating metastatic disease. Although various hypotheses and models have been proposed, no single concept fully explains the mechanism of metastasis or integrates all observations and experimental findings. Recent advancements in metastasis research have refined existing theories and introduced new ones. This review evaluates several novel/emerging theories, focusing on ghost mitochondria (GM), vasculogenic mimicry (VM), and polyploid giant cancer cells (PGCCs).

Nrf2/ASPM axis regulated vasculogenic mimicry formation in hepatocellular carcinoma under hypoxia

BACKGROUND

Hypoxic microenvironment is a common feature of most solid tumors including hepatocellular carcinoma (HCC). Vasculogenic mimicry (VM) formation by tumor cells could provide blood supply to tumor cells under hypoxia. NFE2 like basic leucine zipper (bZIP) transcription factor 2 (Nrf2), a regulator of cellular homeostasis, may promote tumor progression in the hypoxic conditions. However, the role and regulatory mechanisms of Nrf2 in HCC are not fully elucidated.

METHODS

Nrf2 and assembly factor for spindle microtubules (ASPM) expression modulations were conducted by lentiviral transfections. Western blot, immunofluorescence, ChIP-qPCR, dual-luciferase reporter gene assay, flow cytometry, RNA sequencing, multiple bioinformatics databases analysis, cell function assays in vitro, mouse model in vivo and human HCC tissues were employed to assess the effect of Nrf2/ASPM axis on HCC progression under hypoxia.

RESULTS

Nrf2 and ASPM expression facilitated epithelial-mesenchymal transition (EMT), cancer stem cells (CSCs) feature, and VM formation of HCC cells under hypoxia. Furthermore, Nrf2-regulated ASPM expression, via binding directly to the promoter region of ASPM and transcriptionally promoting ASPM expression. ASPM re-expression in Nrf2 knockdown cells or ASPM knockdown in Nrf2 overexpression cells reversed the cellular function caused by Nrf2. Meantime, retinol metabolism pathway was disrupted following abnormal ASPM expression. Nrf2/ASPM axis in murine models accelerated tumor growth and VM, corroborating in vitro findings. All-trans retinoic acid treatment reversed stemness and VM of HCC cells in vitro and in vivo. Clinically, Nrf2 and ASPM expressions were related to poor prognosis of HCC patients.

CONCLUSIONS

Nrf2 drives EMT, CSCs characteristics and VM in HCC under hypoxia through the modulation of ASPM. Retinol metabolism pathway was dysregulated in HCC cells with ASPM overexpression. Nrf2/ASPM axis and related pathway provided potential therapeutic target for HCC.

Vasculogenic mimicry triggers early recidivation and resistance to adjuvant therapy in esophageal cancer

OBJECTIVE

To investigate the impact of vasculogenic mimicry (VM) and postoperative adjuvant therapy on the prognosis and survival of patients with esophageal squamous cell carcinoma (ESCC), as well as to assess whether VM affects the clinical benefit of postoperative adjuvant therapy.

METHODS

This single-center retrospective analysis included patients who underwent radical surgery for ESCC, which was documented in the medical record system. The presence or absence of VM in surgical specimens was determined using double staining with PAS/CD31. Stratification was applied based on adjuvant therapy and VM status. Survival curves and COX modeling were used to analyze the impact of the presence or absence of VM on the benefit of adjuvant therapy and the survival prognosis of patients.

RESULTS

VM-positive patients were more prone to postoperative recurrence and metastasis. VM was identified as an independent risk factor for progression-free survival (PFS) (p < 0.001, 95% CI:1.809-3.852) and overall survival (OS) (p < 0.001, 95% CI:1.603-2.786) in postoperative ESCC. Postoperative adjuvant therapy significantly prolonged PFS (p = 0.008) and OS time (p < 0.001) in patients with stage II and III ESCC, with concurrent chemoradiotherapy being the most effective. However, the presence of VM significantly reduced the benefits of postoperative adjuvant therapy (p < 0.001).

CONCLUSION

VM negatively impacts the prognosis of postoperative ESCC patients and reduces the efficacy of postoperative adjuvant therapy.

Functional roles of microRNAs in vasculogenic mimicry and resistance to therapy in human cancers: an update

INTRODUCTION

Vasculogenic mimicry (VM) alludes to the ability of cancer cells to organize on three-dimensional channel-like structures to obtain nutrients and oxygen. This mechanism confers an aggressive phenotype, metastatic potential, and resistance to chemotherapy resulting in a poor prognosis. Recent studies have been focused on the identification of microRNAs (miRNAs) that regulate the VM representing potential therapeutic targets in cancer.

AREAS COVERED

An overview of the roles of miRNAs on VM development and their functional relationships with tumor microenvironment. The functions of cancer stem-like cells in VM, and resistance to therapy are also discussed. Moreover, the modulation of VM by natural compounds is explored. The clinical significance of deregulated miRNAs as potential therapeutic targets in tumors showing VM is further highlighted.

EXPERT OPINION

The miRNAs are regulators of protein-encoding genes involved in VM; however, their specific expression signatures with clinical value in large cohorts of patients have not been established yet. We considered that genomic profiling of miRNAs could be useful to define some hallmarks of tumors such as stemness, drug resistance, and VM in cancer patients. However, additional studies are needed to establish the relevant role of miRNAs as effective therapeutic targets in tumors that have developed VM.

Exploring the interplay between triple-negative breast cancer stem cells and tumor microenvironment for effective therapeutic strategies

Triple-negative breast cancer (TNBC) is a highly aggressive and metastatic malignancy with poor treatment outcomes. The interaction between the tumor microenvironment (TME) and breast cancer stem cells (BCSCs) plays an important role in the development of TNBC. Owing to their ability of self-renewal and multidirectional differentiation, BCSCs maintain tumor growth, drive metastatic colonization, and facilitate the development of drug resistance. TME is the main factor regulating the phenotype and metastasis of BCSCs. Immune cells, cancer-related fibroblasts (CAFs), cytokines, mesenchymal cells, endothelial cells, and extracellular matrix within the TME form a complex communication network, exert highly selective pressure on the tumor, and provide a conducive environment for the formation of BCSC niches. Tumor growth and metastasis can be controlled by targeting the TME to eliminate BCSC niches or targeting BCSCs to modify the TME. These approaches may improve the treatment outcomes and possess great application potential in clinical settings. In this review, we summarized the relationship between BCSCs and the progression and drug resistance of TNBC, especially focusing on the interaction between BCSCs and TME. In addition, we discussed therapeutic strategies that target the TME to inhibit or eliminate BCSCs, providing valuable insights into the clinical treatment of TNBC.

Vascular mimicry in zebrafish fin regeneration: how macrophages build new blood vessels

Vascular mimicry has been thoroughly investigated in tumor angiogenesis. In this study, we demonstrate for the first time that a process closely resembling tumor vascular mimicry is present during physiological blood vessel formation in tissue regeneration using the zebrafish fin regeneration assay. At the fin-regenerating front, vasculature is formed by mosaic blood vessels with endothelial-like cells possessing the morphological phenotype of a macrophage and co-expressing both endothelial and macrophage markers within single cells. Our data demonstrate that the vascular segments of the regenerating tissue expand, in part, through the transformation of adjacent macrophages into endothelial-like cells, forming functional, perfused channels and contributing to the de novo formation of microvasculature. Inhibiting the formation of tubular vascular-like structures by CVM-1118 prevents vascular mimicry and network formation resulting in a 70% shorter regeneration area with 60% reduced vessel growth and a complete absence of any signs of regeneration in half of the fin area. Additionally, this is associated with a significant reduction in macrophages. Furthermore, depleting macrophages using macrophage inhibitor PLX-3397, results in impaired tissue regeneration and blood vessel formation, namely a reduction in the regeneration area and vessel network by 75% in comparison to controls.

Research progress in tumor angiogenesis and drug resistance in breast cancer

Angiogenesis is considered a hallmark pathophysiological process in tumor development. Aberrant vasculature resulting from tumor angiogenesis plays a critical role in the development of resistance to breast cancer treatments, via exacerbation of tumor hypoxia, decreased effective drug concentrations within tumors, and immune-related mechanisms. Antiangiogenic therapy can counteract these breast cancer resistance factors by promoting tumor vascular normalization. The combination of antiangiogenic therapy with chemotherapy, targeted therapy, or immunotherapy has emerged as a promising approach for overcoming drug resistance in breast cancer. This review examines the mechanisms associated with angiogenesis and the interactions among tumor angiogenesis, the hypoxic tumor microenvironment, drug distribution, and immune mechanisms in breast cancer. Furthermore, this review provides a comprehensive summary of specific antiangiogenic drugs, and relevant studies assessing the reversal of drug resistance in breast cancer. The potential mechanisms underlying these interventions are discussed, and prospects for the clinical application of antiangiogenic therapy to overcome breast cancer treatment resistance are highlighted.

Exploring the metastasis-related biomarker and carcinogenic mechanism in liver cancer based on single cell technology

Background

Hepatocellular carcinoma (HCC) is a fatal primary malignancy characterized by high invasion and migration. We aimed to explore the underlying metastasis-related mechanism supporting the development of HCC.

Methods

The dataset of single cell RNA-seq (GSE149614) were collected for cell clustering by using the Seurat R package, the FindAllMarkers function was used to find the highly expression and defined the cell cluster. The WebGestaltR package was used for the GO and KEGG function analysis of shared genes, the Gene Set Enrichment Analysis (GSVA) was performed by clusterProfiler R package, the hTFtarget database was used to identify the crucial transcription factors (TFs), the Genomics of Drug Sensitivity in Cancer (GDSC) database was used for the drug sensitivity analysis. Finally, the overexpression and trans-well assay was used for gene function analysis.

Results

We obtained 9 cell clusters from the scRNA-seq data, including the nature killer (NK)/T cells, Myeloid cells, Hepatocytes, Epithelial cells, Endothelial cells, Plasma B cells, Smooth muscle cells, B cells, Liver bud hepatic cells. Further cell ecological analysis indicated that the Hepatocytes and Endothelial cell cluster were closely related to the cancer metastasis. Subsequently, the NDUFA4L2-Hepatocyte, GTSE1-Hepatocyte, ENTPD1-Endothelial and NDUFA4L2-Endothelial were defined as metastasis-supporting cell clusters, in which the NDUFA4L2-Hepatocyte cells was closely related to angiogenesis, while the NDUFA4L2-Endothelial was related with the inflammatory response and complement response. The overexpression and trans-well assay displayed that NDUFA4L2 exhibited clearly metastasis-promoting role in HCC progression.

Conclusion

We identified and defined 4 metastasis-supporting cell clusters by using the single cell technology, the specify shared gene was observed and played crucial role in promoting cancer progression, our findings were expected to provide new insight in control cancer metastasis.

MicroRNA-204 Regulates Angiogenesis and Vasculogenic Mimicry in CD44+/CD24- Breast Cancer Stem-like Cells

Tumors have high requirements in terms of nutrients and oxygen. Angiogenesis is the classical mechanism for vessel formation. Tumoral vascularization has the function of nourishing the cancer cells to support tumor growth. Vasculogenic mimicry, a novel intratumoral microcirculation system, alludes to the ability of cancer cells to organize in three-dimensional (3D) channel-like architectures. It also supplies the tumors with nutrients and oxygen. Both mechanisms operate in a coordinated way; however, their functions in breast cancer stem-like cells and their regulation by microRNAs remain elusive. In the present study, we investigated the functional role of microRNA-204 (miR-204) on angiogenesis and vasculogenic mimicry in breast cancer stem-like cells. Using flow cytometry assays, we found that 86.1% of MDA-MB-231 and 92% of Hs-578t breast cancer cells showed the CD44+/CD24- immunophenotype representative of cancer stem-like cells (CSCs). The MDA-MB-231 subpopulation of CSCs exhibited the ability to form mammospheres, as expected. Interestingly, we found that the restoration of miR-204 expression in CSCs significantly inhibited the number and size of the mammospheres. Moreover, we found that MDA-MB-231 and Hs-578t CSCs efficiently undergo angiogenesis and hypoxia-induced vasculogenic mimicry in vitro. The transfection of precursor miR-204 in both CSCs was able to impair the angiogenesis in the HUVEC cell model, which was observed as a diminution in the number of polygons and sprouting cells. Remarkably, miR-204 mimics also resulted in the inhibition of vasculogenic mimicry formation in MDA-MB-231 and Hs-578t CSCs, with a significant reduction in the number of channel-like structures and branch points. Mechanistically, the effects of miR-204 were associated with a diminution of pro-angiogenic VEGFA and β-catenin protein levels. In conclusion, our findings indicated that miR-204 abrogates the angiogenesis and vasculogenic mimicry development in breast cancer stem-like cells, suggesting that it could be a potential tool for breast cancer intervention based on microRNA replacement therapies.

Functional Enrichment Analysis of Tumor Microenvironment-Driven Molecular Alterations That Facilitate Epithelial-to-Mesenchymal Transition and Distant Metastasis

Nowadays, hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths, and identifying the effective factors in causing this disease can play an important role in its prevention and treatment. Tumors provide effective agents for invasion and metastasis to other organs by establishing appropriate communication between cancer cells and the microenvironment. Epithelial-to-mesenchymal transition (EMT) can be mentioned as one of the effective phenomena in tumor invasion and metastasis. Several factors are involved in inducing this phenomenon in the tumor microenvironment, which helps the tumor survive and migrate to other places. It can be effective to identify these factors in the use of appropriate treatment strategies and greater patient survival. This study investigated the molecular differences between tumor border cells and tumor core cells or internal tumor cells in HCC for specific EMT genes. Expression of NOTCH1, ID1, and LST1 genes showed a significant increase at the HCC tumor border. Targeting these genes can be considered as a useful therapeutic strategy to prevent distant metastasis in HCC patients.

Molecular mechanisms of Thrombospondin-2 modulates tumor vasculogenic mimicry by PI3K/AKT/mTOR signaling pathway

Vasculogenic mimicry (VM) differs from the classical tumor angiogenesis model. VM does not depend on endothelial cells; instead, highly aggressive tumor cells mimic endothelial cells to form a vascular-like channel structure. VM mediated by tumor cells is significantly and positively associated with a poor prognosis and low survival rates in patients with highly aggressive cancer. In the treatment of highly aggressive malignancies, the presence of VM is considered an important reason for the unsatisfactory clinical efficacy of anti-tumor-angiogenesis therapy (e.g., therapy targeting vascular endothelial growth factor A). Many targeted therapeutic drugs based on traditional tumor blood vessels have been used clinically. Although some progress has been made in certain tumors, problems such as drug resistance have restricted the expected therapeutic effects. Thrombospondin 2 (THBS2) is one of the most important genes associated with angiogenesis, and this gene exerts angiogenesis-related functions through the PI3K/AKT signaling pathway. Although the PI3K/AKT/mTOR signaling pathway is closely related to the progression of VM, the mechanism by which the promising biomarker THBS2 participates in and regulates tumor VM by activating the PI3K/AKT/mTOR signaling pathway is unclear. In this review, we analyze the monomer structure and biological activity of THBS2, the structure and potential synthesis mechanisms of VM, and the complex mechanisms between THBS2, the PI3K/AKT/mTOR signaling pathway, and VM.

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.

Pharmacological Activity of Matrine in Inhibiting Colon Cancer Cells VM Formation, Proliferation, and Invasion by Downregulating Claudin-9 Mediated EMT Process and MAPK Signaling Pathway

Purpose

Matrine (Mat), the main active ingredient of traditional Chinese herbal plant Sophora flavescens Ait, has significant antitumor effects, but its pharmacological mechanism on colon cancer (CC) remains unclear. This study aimed to investigate the therapeutic effect of Mat on CC as well as the potential mechanism.

Methods

The vasculogenic mimicry (VM) of CC cells was observed by three-dimensional (3D) Matrigel cell culture. Cell proliferation, apoptosis, migration, invasion, and actin filament integrity were detected by CCK8, flow cytometry, wound healing, Transwell and Phalloidin staining assays. qRT-PCR and Western blotting were applied to detect the expression of EMT factors. RNA-sequencing was conducted to screen differentially expressed genes (DEGs), and the GO and KEGG pathway enrichment analyses were performed. Then, the expression of the key MAPK pathway genes and the target gene Claudin-9 (Cldn9) were analyzed. RNA interference was used to silence Cldn9 expression, and the effects of Cldn9 silencing and simultaneous treatment with Mat on VM formation, proliferation, apoptosis, invasion, and migration were investigated. Finally, the expression of EMT factors and MAPK pathway key genes was detected.

Results

CT26 cells formed the most typical VM structure. Mat disrupted the VM of CT26 cells, significantly suppressed their proliferation, migration, invasion, actin filament integrity, induced apoptosis, and inhibited EMT process. RNA-sequencing revealed 163 upregulated genes and 333 downregulated genes in Mat-treated CT26 cells, and the DEGs were significantly enriched in cell adhesion molecules and MAPK signaling pathways. Further confirmed that Mat significantly inhibited the phosphorylation levels of JNK and ERK, and the target gene Cldn9 was significantly upregulated in human CC tissues. Silencing Cldn9 markedly inhibited the VM, proliferative activity, invasiveness, and actin filament integrity of CT26 cells, blocked the EMT process, and downregulated the phosphorylation of JNK and ERK, whereas Mat intervention further strengthened the above trends.

Conclusion

This study indicated that Mat may synergistically inhibit the EMT process and MAPK signaling pathway through downregulation Cldn9, thereby exerting pharmacological effects on inhibiting VM formation, proliferation, and invasion of CC cells.

The Inhibition of the FGFR/PI3K/Akt Axis by AZD4547 Disrupts the Proangiogenic Microenvironment and Vasculogenic Mimicry Arising from the Interplay between Endothelial and Triple-Negative Breast Cancer Cells

Vasculogenic mimicry (VM), a process in which aggressive cancer cells form tube-like structures, plays a crucial role in providing nutrients and escape routes. Highly plastic tumor cells, such as those with the triple-negative breast cancer (TNBC) phenotype, can develop VM. However, little is known about the interplay between the cellular components of the tumor microenvironment and TNBC cells' VM capacity. In this study, we analyzed the ability of endothelial and stromal cells to induce VM when interacting with TNBC cells and analyzed the involvement of the FGFR/PI3K/Akt pathway in this process. VM was corroborated using fluorescently labeled TNBC cells. Only endothelial cells triggered VM formation, suggesting a predominant role of paracrine/juxtacrine factors from an endothelial origin in VM development. Via immunocytochemistry, qPCR, and secretome analyses, we determined an increased expression of proangiogenic factors as well as stemness markers in VM-forming cancer cells. Similarly, endothelial cells primed by TNBC cells showed an upregulation of proangiogenic molecules, including FGF, VEGFA, and several inflammatory cytokines. Endothelium-dependent TNBC-VM formation was prevented by AZD4547 or LY294002, strongly suggesting the involvement of the FGFR/PI3K/Akt axis in this process. Given that VM is associated with poor clinical prognosis, targeting FGFR/PI3K/Akt pharmacologically may hold promise for treating and preventing VM in TNBC tumors.

Multiple Roles of LOXL2 in the Progression of Hepatocellular Carcinoma and Its Potential for Therapeutic Targeting

LOXL2, a copper-dependent amine oxidase, has emerged as a promising therapeutic target in hepatocellular carcinoma (HCC). Increased LOXL2 expression in HCC has been linked with an aggressive phenotype and represents a poor prognostic factor. Here, we focus on the mechanisms through which LOXL2 orchestrates multiple oncogenic functions in HCC development. We performed a review of the current knowledge on the roles LOXL2 performs in the modulation of the HCC tumor microenvironment, formation of premetastatic niches, and epithelial-mesenchymal transition. We also highlighted the complex interplay between LOXL2 and hypoxia, angiogenesis, and vasculogenic mimicry in HCC. At the end of the review, we summarize the current LOXL2 inhibitors and discuss their potential in HCC precision treatment.

The role of TOP2A in immunotherapy and vasculogenic mimicry in non-small cell lung cancer and its potential mechanism

Type IIA topoisomerase (TOP2A) is significantly associated with malignant tumor development, invasion, treatment and its prognosis, and has been shown to be a therapeutic target against cancer. In contrast, the role of TOP2A in the immunotherapy of non-small cell lung cancer as well as in Vasculogenic mimicry (VM) formation and its potential mechanisms are unclear. The aim of this study was to investigate the role of TOP2A in proliferation, skeleton regulation, motility and VM production in non-small cell lung cancer and its mechanisms by using bioinformatics tools and molecular biology experiments. Subgroup analysis showed that the low-risk group had a better prognosis, while the high-risk group was positively correlated with high tumor mutational load, M1-type macrophage infiltration, immune checkpoint molecule expression, and immunotherapy efficacy. As confirmed by further clinical specimens, the presence of TOP2A and VM was significantly and positively correlated with poor prognosis. Our study established a model based on significant co-expression of TOP2A genes, which significantly correlated with mutational load and immunotherapy outcomes in patients with non-small cell lung cancer. Further mechanistic exploration suggests that TOP2A plays an important role in immunotherapy and VM formation in NSCLC through upregulation of Wnt3a and PD-L1 expression.

Gastric Cancer Vascularization and the Contribution of Reactive Oxygen Species

Blood vessels are the most important way for cancer cells to survive and diffuse in the body, metastasizing distant organs. During the process of tumor expansion, the neoplastic mass progressively induces modifications in the microenvironment due to its uncontrolled growth, generating a hypoxic and low pH milieu with high fluid pressure and low nutrients concentration. In such a particular condition, reactive oxygen species play a fundamental role, enhancing tumor proliferation and migration, inducing a glycolytic phenotype and promoting angiogenesis. Indeed, to reach new sources of oxygen and metabolites, highly aggressive cancer cells might produce a new abnormal network of vessels independently from endothelial cells, a process called vasculogenic mimicry. Even though many molecular markers and mechanisms, especially in gastric cancer, are still unclear, the formation of such intricate, leaky and abnormal vessel networks is closely associated with patients' poor prognosis, and therefore finding new pharmaceutical solutions to be applied along with canonical chemotherapies in order to control and normalize the formation of such networks is urgent.

Multiple stimulus-response berberine plus baicalin micelles with particle size-charge-release triple variable properties for breast cancer therapy

OBJECTIVE

The aim was to develop a nanoscale drug delivery system with enzyme responsive and acid sensitive particle size and intelligent degradation aiming to research the inhibitory effect on breast cancer.

SIGNIFICANCE

The delivery system addressed the problems of tissue targeting, cellular internalization, and slow drug release at the target site, which could improve the efficiency of drug delivery and provide a feasible therapeutic approach for breast cancer.

METHODS

The acid sensitive functional material DSPE-PEG₂₀₀₀-dyn-PEG-R9 was synthesized by Michael addition reaction. Then, the berberine plus baicalin intelligent micelles were prepared by thin-film hydration. Subsequently, we characterized the physical and chemical properties of berberine plus baicalin intelligent micelles, evaluated its anti-tumor effects in vivo and in vitro.

RESULTS

The target molecule was successfully synthesized, and the intelligent micelles showed excellent chemical and physical properties, delayed drug release and high encapsulation efficiency. In vitro and in vivo experiments also confirmed that the intelligent micelles could effectively target tumor sites, penetrate tumor tissues, enrich in tumor cells, inhibit tumor cell proliferation, inhibit tumor cell invasion and migration, and induce tumor cell apoptosis.

CONCLUSION

Berberine plus baicalin intelligent micelles have excellent anti-tumor effects and no toxicity to normal tissues, which provides a new potential drug delivery strategy for the treatment of breast cancer.

Molecular vasculogenic mimicry-Related signatures predict clinical outcomes and therapeutic responses in bladder cancer: Results from real-world cohorts

Bladder cancer (BLCA) is a heterogeneous disease, and there are many classical molecular subtypes that reflect tumor immune microenvironment (TME) heterogeneity but their clinical utility is limited and correct individual treatment and prognosis cannot be predicted based on them. To find reliable and effective biomarkers and tools for predicting patients' clinical responses to several therapies, we developed a new systemic indicator of molecular vasculogenic mimicry (VM)-related genes mediated by molecular subtypes based on the Xiangya cohort and additional external BLCA cohorts using a random forest algorithm. A correlation was then done between the VM_Score and classical molecular subtypes, clinical outcomes, immunophenotypes, and treatment options for BLCA. With the VM_Score, it is possible to predict classical molecular subtypes, immunophenotypes, prognosis, and therapeutic potential of BLCA with high accuracy. The VM_Scores of high levels indicate a more anticancer immune response but a worse prognosis due to a more basal and inflammatory phenotype. The VM_Score was also found associated with low sensitivity to antiangiogenic and targeted therapies targeting the FGFR3, β-catenin, and PPAR-γ pathways but with high sensitivity to cancer immunotherapy, neoadjuvant chemotherapy, and radiotherapy. A number of aspects of BLCA biology were reflected in the VM_Score, providing new insights into precision medicine. Additionally, the VM_Score may be used as an indicator of pan-cancer immunotherapy response and prognosis.

Nectins and Nectin-like Molecules in Colorectal Cancer: Role in Diagnostics, Prognostic Values, and Emerging Treatment Options: A Literature Review

In 2020, colorectal cancer was the third most common type of cancer worldwide with a clearly visible increase in the number of cases each year. With relatively high mortality rates and an uncertain prognosis, colorectal cancer is a serious health problem. There is an urgent need to investigate its specific mechanism of carcinogenesis and progression in order to develop new strategies of action against this cancer. Nectins and Nectin-like molecules are cell adhesion molecules that take part in a plethora of essential processes in healthy tissues as well as mediating substantial actions for tumor initiation and evolution. Our understanding of their role and a viable application of this in anti-cancer therapy has rapidly improved in recent years. This review summarizes the current data on the role nectins and Nectin-like molecules play in colorectal cancer.

Cancer-associated fibroblasts in nonsmall cell lung cancer: From molecular mechanisms to clinical implications

Lung cancer is the common and leading cause of cancer death worldwide. The tumor microenvironment has been recognized to be instrumental in tumorigenesis. To have a deep understanding of the molecular mechanism of nonsmall cell lung carcinoma (NSCLC), cancer-associated fibroblasts (CAFs) have gained increasing research interests. CAFs belong to the crucial and dominant cell population in the tumor microenvironment to support the cancer cells. The interplay and partnership between cancer cells and CAFs contribute to each stage of tumorigenesis. CAFs exhibit prominent heterogeneity and secrete different kinds of cytokines and chemokines, growth factors and extracellular matrix proteins involved in cancer cell proliferation, invasion, metastasis and chemoresistance. Many studies focused on the protumorigenic functions of CAFs, yet many challenges about the heterogeneity of CAFS remain unresolved. This review comprehensively summarized the tumor-promoting role and molecular mechanisms of CAFs in NSCLC, including their origin, phenotypic changes and heterogeneity and their functional roles in carcinogenesis. Meanwhile, we also highlighted the updated molecular classifications based on the molecular features and functional roles of CAFs. With the development of cutting-edge platforms and further investigations of CAFs, novel therapeutic strategies for accurately targeting CAFs in NSCLC may be developed based on the increased understanding of the relevant molecular mechanisms.

Vandetanib alters the tumoricidal capacity of human breast cancer stem cells via inhibiting vasculogenic capacity

Introduction

The inhibition of vascularization into tumor stroma as well as dynamic cell growth is the center of attention. Here, we aimed to examine the role of vandetanib on angiogenesis capacity of breast cancer stem cell (CSCs).

Methods

MDA-MB-231 cells were exposed to different doses of vandetanib and survival rate was monitored. Stimulatory effects of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and epidermal growth factor (EGF) were evaluated in vandetanib-treated MDA-MB-231 cells. In vitro tubulogenesis capacity was studied on the Matrigel surface. The synergistic effects of vandetanib on cell survival were also assessed after PI3K and/or Wnt3a inhibition. Vascular endothelial (VE)-cadherin, matrix metalloproteinase-2 (MMP-2), -9, Wnt3a, and p-Akt/Akt ratio were measured using western blotting.

Results

Vandetanib reduced survival rate in a dose-dependent manner (P<0.05). Proliferative effects associated with VEGF, FGF, and EGF were blunted in these cells pre-exposed to vandetanib (P<0.05). The microcirculation pattern's triple-negative breast cancer (TNBC) was suppressed by 1, 5 µM of vandetanib (P<0.05). Hence 1, 5 µM of vandetanib potentially decreased the population of CD24- cells. 1 and 5 µM of vandetanib inhibited cell proliferation by blocking PI3K and Wnt3a pathways and decreased the p-Akt/Akt ratio, Wnta3 protein levels (P<0.05). 1 and 5 µM vandetanib combined with PI3K inhibitor diminished metastatic markers including, MMP-2, and MMP-9. The concurrent treatment (PI3K, inhibitor+ 1, 5 µM vandetanib) also considerably reduced epithelial-mesenchymal transition (EMT) markers such as VE-cadherin (P<0.05).

Conclusion

Vandetanib suppressed vasculogenic mimicry (VM) networking through blunting stemness properties, coincided with suppression of VE-cadherin in CSCs.

LncRNA n339260 functions in hepatocellular carcinoma progression via regulation of miRNA30e-5p/TP53INP1 expression

BACKGROUND

Currently, the molecular mechanism of the interaction between lncRNAs and microRNAs (miRNAs) and the target of miRNAs in tumor vasculogenic mimicry (VM) formation have not been clarified. Our aim is to study the interaction between lncRNA n339260 and miRNA30e-5p in the formation of VM.

METHODS

Animal xenografts were established, 104 hepatocellular carcinoma (HCC) patients' frozen tissues were obtained and HCC cells in vitro were used to observe the role of n339260 in HCC progression.

RESULTS

In vivo experiment showed lncRNA n339260 promoted tumor growth and VM formation. LncRNA n339260 and miRNA30e-5p were found to be associated with VM formation, metastasis and survival time in HCC patients. In vitro experiment showed that LncRNA n339260 could inhibit miRNA30e-5p expression and TP53INP1 was found to be the downstream targets of miRNA30e-5p. Snail, MMP2, MMP9, VE-cadherin, vimentin and N-cadherin overexpression and the downregulation of TP53INP1 and E-cadherin were observed in HCCLM3 and HepG2 cells overexpressing lncRNA n339260 or in cells with decreased expression of miRNA30e-5p.

CONCLUSION

LncRNA n339260 promotes the development of VM, and lncRNA n339260 may enhance Snail expression by decreasing the expression of miRNA30e-5p, thereby reducing TP53INP1 expression. Therefore, a potential lncRNA n339260- miRNA30e-5p- TP53INP1 regulatory axis was associated with HCC progression.

Immunotherapy checkpoints in ovarian cancer vasculogenic mimicry: Tumor immune microenvironments, and drugs

Vasculogenic mimicry (VM), a vessel-like structure independent of endothelial cells, commonly exists in solid tumors which requires blood vessels to grow. As a special source of blood supply for tumor progression to a more aggressive state, VM has been observed in a variety of human malignant tumors and is tightly associated with tumor proliferation, invasion, metastasis, and poor patient prognosis. So far, various factors, including immune cells and cytokines, were reported to regulate ovarian cancer progression by influencing VM formation. Herein, we review the mechanisms that regulate VM formation in ovarian cancer and the effect of cells, cytokines, and signaling molecules in the tumor microenvironment on VM formation, Furthermore, we summarize the current clinical application of drugs targeting VM formation.

Curcuminoids as Modulators of EMT in Invasive Cancers: A Review of Molecular Targets With the Contribution of Malignant Mesothelioma Studies

Curcuminoids, which include natural acyclic diarylheptanoids and the synthetic analogs of curcumin, have considerable potential for fighting against all the characteristics of invasive cancers. The epithelial-to-mesenchymal transition (EMT) is a fundamental process for embryonic morphogenesis, however, the last decade has confirmed it orchestrates many features of cancer invasiveness, such as tumor cell stemness, metabolic rewiring, and drug resistance. A wealth of studies has revealed EMT in cancer is in fact driven by an increasing number of parameters, and thus understanding its complexity has now become a cornerstone for defining future therapeutic strategies dealing with cancer progression and metastasis. A specificity of curcuminoids is their ability to target multiple molecular targets, modulate several signaling pathways, modify tumor microenvironments and enhance the host’s immune response. Although the effects of curcumin on these various parameters have been the subject of many reviews, the role of curcuminoids against EMT in the context of cancer have never been reviewed so far. This review first provides an updated overview of all EMT drivers, including signaling pathways, transcription factors, non-coding RNAs (ncRNAs) and tumor microenvironment components, with a special focus on the most recent findings. Secondly, for each of these drivers the effects of curcumin/curcuminoids on specific molecular targets are analyzed. Finally, we address some common findings observed between data reported in the literature and the results of investigations we conducted on experimental malignant mesothelioma, a model of invasive cancer representing a useful tool for studies on EMT and cancer.

The Vascular Microenvironment in Glioblastoma: A Comprehensive Review

Glioblastoma multiforme, the deadliest primary brain tumor, is characterized by an excessive and aberrant neovascularization. The initial expectations raised by anti-angiogenic drugs were soon tempered due to their limited efficacy in improving the overall survival. Intrinsic resistance and escape mechanisms against anti-VEGF therapies evidenced that tumor angiogenesis is an intricate multifaceted phenomenon and that vessels not only support the tumor but exert indispensable interactions for resistance and spreading. This holistic review covers the essentials of the vascular microenvironment of glioblastoma, including the perivascular niche components, the vascular generation patterns and the implicated signaling pathways, the endothelial–tumor interrelation, and the interconnection between vessel aberrancies and immune disarrangement. The revised concepts provide novel insights into the preclinical models and the potential explanations for the failure of conventional anti-angiogenic therapies, leading to an era of new and combined anti-angiogenic-based approaches.

Expression of Dickkopf-1 and Twist2 in Cervical Squamous Cell Carcinoma and Their Correlation with Vasculogenic Mimicry

Wnt/β-catenin signaling, epithelial-mesenchymal transition (EMT), and vasculogenic mimicry (VM) all exert important effects in tumors. Dickkopf-1 (DKK1) is an antagonist of the Wnt/β-catenin, Twist homolog 2 (Twist2) is a key EMT transcription factor involved in cancer cell migration and invasion, and VM participates in the progression and metastasis of a variety of cancers. However, the correlation of DKK1, Twist2, and VM in cervical squamous cell carcinoma(CSC) is still unclear. This study focuses on correlations among these factors as well as their correlation with clinicopathologic data and survival in CSC. DKK1, Twist2, and VM expressions were immunohistochemically examined in 116 CSC tissues and 37 normal cervical tissues. Furthermore, clinical data were processed. The expression levels of these three factors differed between CSC and normal tissues. VM was observed in CSC, but not in normal cervical tissues. Twist2 expression was high in CSC but low in normal cervical tissues, whereas DKK1 expression had the opposite pattern. Tumor cells with VM had a high expression of Twist2 and low expression of DKK1. In addition, DKK1 expression was negatively correlated with Twist2 expression. Analyzing the relationships of DKK1, Twist2, and VM with the data of patients with CSC revealed that DKK1 expression was negatively correlated with the clinical stage, degree of differentiation, depth of infiltration, and lymph node metastasis of tumors. VM and Twist2 expression were positively correlated with the degree of differentiation, the depth of infiltration, and lymph node metastasis. The positive rate of VM was greater in stage II than in stage I. The patients who expressed VM and Twist2 had a reduced overall survival (OS) when compared with patients not expressing these proteins. However, the patients who expressed DKK1 had an increased OS when compared with patients who did not show any DKK1 expression. Multivariate analysis indicated that the expressions of DKK1, Twist2, and VM were prognostic factors for CSC. VM and the expression of DKK1 and Twist2 can be the potential prognostic biomarkers and therapeutic targets for CSC.

Sp1 Plays a Key Role in Vasculogenic Mimicry of Human Prostate Cancer Cells

Sp1 transcription factor regulates genes involved in various phenomena of tumor progression. Vasculogenic mimicry (VM) is the alternative neovascularization by aggressive tumor cells. However, there is no evidence of the relationship between Sp1 and VM. This study investigated whether and how Sp1 plays a crucial role in the process of VM in human prostate cancer (PCa) cell lines, PC-3 and DU145. A cell viability assay and three-dimensional culture VM tube formation assay were performed. Protein and mRNA expression levels were detected by Western blot and reverse transcriptase-polymerase chain reaction, respectively. The nuclear twist expression was observed by immunofluorescence assay. A co-immunoprecipitation assay was performed. Mithramycin A (MiA) and Sp1 siRNA significantly decreased serum-induced VM, whereas Sp1 overexpression caused a significant induction of VM. Serum-upregulated vascular endothelial cadherin (VE-cadherin) protein and mRNA expression levels were decreased after MiA treatment or Sp1 silencing. The protein expression and the nuclear localization of twist were increased by serum, which was effectively inhibited after MiA treatment or Sp1 silencing. The interaction between Sp1 and twist was reduced by MiA. On the contrary, Sp1 overexpression enhanced VE-cadherin and twist expressions. Serum phosphorylated AKT and raised matrix metalloproteinase-2 (MMP-2) and laminin subunit 5 gamma-2 (LAMC2) expressions. MiA or Sp1 silencing impaired these effects. However, Sp1 overexpression upregulated phosphor-AKT, MMP-2 and LAMC2 expressions. Serum-upregulated Sp1 was significantly reduced by an AKT inhibitor, wortmannin. These results demonstrate that Sp1 mediates VM formation through interacting with the twist/VE-cadherin/AKT pathway in human PCa cells.

Vasculogenic Mimicry-An Overview

Vasculogenic mimicry (VM), a tumor microcirculation model found in melanoma in the last 20 years, is a vascular channel-like structure composed of tumor cells, but without endothelial cells, that stains positive for periodic acid-Schiff (PAS) and negative staining for CD31. VM provides, to the highly aggressive malignant tumor cells, adequate oxygen and nutrient supply for tumor growth and subsequent metastasis process and its presence are related to poor prognosis in patients. VM is independent of endothelial cells, which may partly explain why angiogenesis drug inhibitors have not achieved the expected success for cancer treatment.

Microenvironment of Cancer Stem Cells

Microenvironment of cancer stem cells (CSCs) consists of a variety of cells and inter-cellular matrix and communications of the components. The microenvironment of CSCs maintains the stemness feature of the CSCs. Several cell types which communicate each other via signaling molecules surrounding CSCs are main factors of the CSC microenvironment. A key question is "What kind of information the cells exchange in the CSC microenvironment?" to reveal the microenvironment and CSC features. Components and molecular markers of CSC microenvironment, signaling cross-talks in CSC microenvironment, and targeting CSC microenvironment are focused in this review.

Comparative mRNA/micro-RNA co-expression network drives melanomagenesis by promoting epithelial-mesenchymal transition and vasculogenic mimicry signaling

This study aimed to identify a novel disease-associated differentially co-expressed mRNA-microRNA (miRNA) that is associated with vasculogenic mimicry (VM) and epithelial-to-mesenchymal transition (EMT) network at different stages of melanoma. By applying weighted gene co-expression network analysis, we constructed a VM+EMT biological network with the available microarray dataset downloaded from a public database. Quantitative real-time PCR, immunohistochemical staining, and CD31-periodic acid solution dual staining were performed to confirm the expression of genes associated with EMT and VM formation in subjects with malignant melanoma (n = 18) and primary melanoma (n = 13) and in healthy subjects (n = 10). Our findings suggested that phosphatidylserine-specific phospholipase A1-alpha (PLA1A) and dermokine (DMKN) genes function as oncogenes that trigger VM and EMT processes during melanomagenesis on interaction with miR-370, miR-563, and miR-770-5p. PLA1A and DMKN genes can be considered potential VM+EMT network-based diagnostic biomarkers for distinguishing between melanoma patients. We postulate that a network with altered PLA1A/miR-563 and DMNK/miR-770-5p/miR-370 may contribute to melanomagenesis by triggering the EMT signaling pathway and VM formation. This study provides a potentially valuable approach for the early diagnosis and prognosis of melanoma progression.

New Peptide-Drug Conjugates for Precise Targeting of SORT1-Mediated Vasculogenic Mimicry in the Tumor Microenvironment of TNBC-Derived MDA-MB-231 Breast and Ovarian ES-2 Clear Cell Carcinoma Cells

Vasculogenic mimicry (VM) is defined as the formation of microvascular channels by genetically deregulated cancer cells and is often associated with high tumor grade and cancer therapy resistance. This microcirculation system, independent of endothelial cells, provides oxygen and nutrients to tumors, and contributes also in part to metastasis. VM has been observed in ovarian cancer and in triple negative breast cancer (TNBC) and shown to correlate with decreased overall cancer patient survival. Thus, strategies designed to inhibit VM may improve cancer patient treatments. In this study, sortilin (SORT1) receptor was detected in in vitro 3D capillary-like structures formed by ES-2 ovarian cancer and MDA-MB-231 TNBC-derived cells when grown on Matrigel. SORT1 gene silencing or antibodies directed against its extracellular domain inhibited capillary-like structure formation. In vitro, VM also correlated with increased gene expression of matrix metalloproteinase-9 (MMP-9) and of the cancer stem cell marker CD133. In vivo ES-2 xenograft model showed PAS⁺/CD31^- VM structures (staining positive for both SORT1 and CD133). TH1904, a Doxorubicin-peptide conjugate that is internalized by SORT1, significantly decreased in vitro VM at low nM concentrations. In contrast, VM was unaffected by unconjugated Doxorubicin or Doxil (liposomal Doxorubicin) up to μM concentrations. TH1902, a Docetaxel-peptide conjugate, altered even more efficiently in vitro VM at pM concentrations. Overall, current data evidence for the first time that 1) SORT1 itself exerts a crucial role in both ES-2 and MDA-MB-231 VM, and that 2) VM in these cancer cell models can be efficiently inhibited by the peptide-drug conjugates TH1902/TH1904. These new findings also indicate that both peptide-drug conjugates, in addition to their reported cytotoxicity, could possibly inhibit VM in SORT1-positive TNBC and ovarian cancer patients.

Pro-angiogenic activity and vasculogenic mimicry in the tumor microenvironment by leptin in cancer

The acquired ability to induce the formation of a functional vasculature is a hallmark of cancer. Blood vessels in tumors are formed through various mechanisms, among the most important in cancer biology, angiogenesis, and vasculogenic mimicry have been described. Leptin is one of the main adipokines secreted by adipocytes in normal breast tissue and the tumor microenvironment. Here, we provide information on the relationship between leptin and the development of angiogenesis and vasculogenic mimicry in different types of cancer. Here, we report that leptin activates different pathways such as JAK-STAT3, MAPK/ERK, PKC, JNK, p38, and PI3K-Akt to induce the expression of various angiogenic factors and vasculogenic mimicry. In vivo models, leptin induces blood vessel formation through the PI3K-Akt-mTOR pathway. Interestingly, the relationship between leptin and vasculogenic mimicry was more significant in breast cancer. The information obtained suggests that leptin could be playing an essential role in tumor survival and metastasis through the induction of vascular mechanisms such as angiogenesis and vasculogenic mimicry; thus, leptin-induced pathways could be suggested as a promising therapeutic target.

Multilayered and heterogeneous hydrogel construct printing system with crosslinking aerosol

Microextrusion bioprinting has been used to recreate the complex architecture and composition of a physiological system through the quick and accurate handling of various biomaterials. However, existing techniques are limited in precisely fabricating complex constructs, including multilayers and heterogeneous patterns with distinct regions, because the extruded bioink spreads rapidly upon contact with the substrate and is partially mixed with subsequently printed bioinks. This issue leads to difficulties in accurately and stably constructing multi-material structures with clear interfaces for prolonged printing before gelation. To fabricate multilayered and heterogeneous constructs, a bioprinting system should be able to continuously extrude various biomaterials and simultaneously crosslink the extruded bioink to stabilize the printed construct. In this study, a multiple-bioink printing system was developed by integrating a multibarrel nozzle for extruding multiple bioinks with a nebulizer for simultaneous crosslinking. The crosslinking aerosol sprayed from the nebulizer was able to gelate the various hydrogel bioinks as they were extruded through the multibarrel nozzle. Such aerosol-based crosslinking improved printing resolution and stability. The developed bioprinting system showed the possibility of recapitulating the physiological complex architecture such as a cancer microenvironment with well-defined interfaces between regions of different mechanical properties and cellular compositions. Using the integrated bioprinting system, a multilayered and heterogeneous construct was printed with four bioinks, including three types of cells (breast cancer cells, stromal cells, and vascular endothelial cells). The printed biological model was characterized by analyzing cancer cell migration and vascular network formation. The developed multiple-bioink printing system is expected to be highly efficient in recapitulating complex tissues and their environments with compartmentalized regions.

Enhanced Vasculogenic Capacity Induced by 5-Fluorouracil Chemoresistance in a Gastric Cancer Cell Line

Chemotherapy is still widely used as a coadjutant in gastric cancer when surgery is not possible or in presence of metastasis. During tumor evolution, gatekeeper mutations provide a selective growth advantage to a subpopulation of cancer cells that become resistant to chemotherapy. When this phenomenon happens, patients experience tumor recurrence and treatment failure. Even if many chemoresistance mechanisms are known, such as expression of ATP-binding cassette (ABC) transporters, aldehyde dehydrogenase (ALDH1) activity and activation of peculiar intracellular signaling pathways, a common and universal marker for chemoresistant cancer cells has not been identified yet. In this study we subjected the gastric cancer cell line AGS to chronic exposure of 5-fluorouracil, cisplatin or paclitaxel, thus selecting cell subpopulations showing resistance to the different drugs. Such cells showed biological changes; among them, we observed that the acquired chemoresistance to 5-fluorouracil induced an endothelial-like phenotype and increased the capacity to form vessel-like structures. We identified the upregulation of thymidine phosphorylase (TYMP), which is one of the most commonly reported mutated genes leading to 5-fluorouracil resistance, as the cause of such enhanced vasculogenic ability.

Lineage Plasticity in Cancer: The Tale of a Skin-Walker

Lineage plasticity, the switching of cells from one lineage to another, has been recognized as a cardinal property essential for embryonic development, tissue repair and homeostasis. However, such a highly regulated process goes awry when cancer cells exploit this inherent ability to their advantage, resulting in tumorigenesis, relapse, metastasis and therapy resistance. In this review, we summarize our current understanding on the role of lineage plasticity in tumor progression and therapeutic resistance in multiple cancers. Lineage plasticity can be triggered by treatment itself and is reported across various solid as well as liquid tumors. Here, we focus on the importance of lineage switching in tumor progression and therapeutic resistance of solid tumors such as the prostate, lung, hepatocellular and colorectal carcinoma and the myeloid and lymphoid lineage switch observed in leukemias. Besides this, we also discuss the role of epithelial-mesenchymal transition (EMT) in facilitating the lineage switch in biphasic cancers such as aggressive carcinosarcomas. We also discuss the mechanisms involved, current therapeutic approaches and challenges that lie ahead in taming the scourge of lineage plasticity in cancer.

Tumor Vessels Fuel the Fire in Glioblastoma

Glioblastoma, a subset of aggressive brain tumors, deploy several means to increase blood vessel supply dedicated to the tumor mass. This includes typical program borrowed from embryonic development, such as vasculogenesis and sprouting angiogenesis, as well as unconventional processes, including co-option, vascular mimicry, and transdifferentiation, in which tumor cells are pro-actively engaged. However, these neo-generated vascular networks are morphologically and functionally abnormal, suggesting that the vascularization processes are rather inefficient in the tumor ecosystem. In this review, we reiterate the specificities of each neovascularization modality in glioblastoma, and, how they can be hampered mechanistically in the perspective of anti-cancer therapies.

Expression of STAT3 and vasculogenic mimicry in gallbladder carcinoma promotes invasion and metastasis

Surgical treatment of gallbladder carcinoma remains challenging, while targeted therapy has been demonstrated to have potential. In the present study, the effect of signal transducer and activator of transcription 3 (STAT3) expression and vasculogenic mimicry (VM) on the occurrence and development of gallbladder carcinoma was evaluated. A total of 72 patients with gallbladder carcinoma and 10 patients with chronic cholecystitis were examined. Immunohistochemical staining was performed to determine the positive expression rates of STAT3. Periodic acid Schiff CD34 double staining was performed to detect VM in the gallbladder carcinoma group. STAT3 expression and VM in gallbladder carcinoma tissues was compared among patients with different clinical characteristics. In postoperative patients with gallbladder cancer, the relationship of the postoperative recurrence time with STAT3 expression and VM was assessed. STAT3 expression in gallbladder carcinoma tissue was significantly higher than that in cholecystitis tissue (P<0.05). STAT3 expression levels and VM were positively correlated in gallbladder carcinoma tissue. STAT3 protein expression in gallbladder carcinoma tissues differed significantly among patients with different degrees of differentiation and clinical stages (P<0.05). Among the 51 patients who completed the 3-year follow-up, the mean time to relapse was 17.353 and 35.647 months in those with high and low STAT3 expression, respectively, with significant differences (P<0.05). The VM structure was detected in 47 cases (92.15%) and not detected in four cases (7.84%), which exhibited no immediate recurrence after surgery, and the difference in the mean postoperative recurrence time was significant (22.38 vs. 36.00 months, respectively; P<0.05). In gallbladder carcinoma tissues, a lower degree of differentiation, higher malignancy degree and higher clinical stage were associated with higher expression of STAT3 and VM. Thus, STAT3 may promote VM formation in the process of tumor occurrence, development and metastasis. Therefore, STAT3 as a regulatory target, may inhibit the proliferation and invasion of tumor cells and block the development of VM, thereby representing a suitable target for antitumor angiogenesis therapy.

To be or not to be: endothelial cell plasticity in development, repair, and disease

Endothelial cells display an extraordinary plasticity both during development and throughout adult life. During early development, endothelial cells assume arterial, venous, or lymphatic identity, while selected endothelial cells undergo additional fate changes to become hematopoietic progenitor, cardiac valve, and other cell types. Adult endothelial cells are some of the longest-lived cells in the body and their participation as stable components of the vascular wall is critical for the proper function of both the circulatory and lymphatic systems, yet these cells also display a remarkable capacity to undergo changes in their differentiated identity during injury, disease, and even normal physiological changes in the vasculature. Here, we discuss how endothelial cells become specified during development as arterial, venous, or lymphatic endothelial cells or convert into hematopoietic stem and progenitor cells or cardiac valve cells. We compare findings from in vitro and in vivo studies with a focus on the zebrafish as a valuable model for exploring the signaling pathways and environmental cues that drive these transitions. We also discuss how endothelial plasticity can aid in revascularization and repair of tissue after damage- but may have detrimental consequences under disease conditions. By better understanding endothelial plasticity and the mechanisms underlying endothelial fate transitions, we can begin to explore new therapeutic avenues.

SOX7 blocks vasculogenic mimicry in oral squamous cell carcinoma

BACKGROUND

Vasculogenic mimicry (VM) is the formation of an alternative circulatory system by aggressive tumor cells. The characteristics of VM and its underlying mechanism in oral squamous cell carcinoma (OSCC) remain unclear. This study aims to determine the relationship between VM in OSCC tissues and clinical outcomes and to investigate the biological role of SOX7 in VM in OSCC cells.

METHODS

CD31/PAS staining was performed to evaluate VM in OSCC tissue. The relationships between VM and clinicopathological variables, and VM and SOX7 levels were analyzed. The correlation between SOX7 levels and cancer cohorts was investigated using in silico analysis. VM formation assay was performed to observe VM in vitro. To investigate the role of SOX7 in VM formation, SOX7 was transiently over-expressed in SCC-9 cells. VM-modulating genes were identified by Western blotting.

RESULTS

We found a positive correlation between VM and lymph node metastasis and patient survival in OSCC (p = 0.003). In silico analysis from The Cancer Genome Atlas and Gene Expression Omnibus database showed that down-regulation of SOX7 expression was significantly correlated with OSCC patients (p = 0.0187) and lymph node metastasis (p = 0.0017). We also found that the presence of VM in OSCC tissue was inversely associated with SOX7 expression (p = 0.020). We observed that overexpression of SOX7 impaired VM formation by reducing the expression of VE-cadherin, thereby inhibiting cell migration and invasion.

CONCLUSION

These results suggest that SOX7 plays an important role in the regulation of VM formation and may inhibit OSCC metastasis.

Regulatory mechanisms and therapeutic targeting of vasculogenic mimicry in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a typical hyper-vascular solid tumor; aberrantly rich in tumor vascular network contributes to its malignancy. Conventional anti-angiogenic therapies seem promising but transitory and incomplete efficacy on HCC. Vasculogenic mimicry (VM) is one of functional microcirculation patterns independent of endothelial vessels which describes the plasticity of highly aggressive tumor cells to form vasculogenic-like networks providing sufficient blood supply for tumor growth and metastasis. As a pivotal alternative mechanism for tumor vascularization when tumor cells undergo lack of oxygen and nutrients, VM has an association with the malignant phenotype and poor clinical outcome for HCC, and may challenge the classic anti-angiogenic treatment of HCC. Current studies have contributed numerous findings illustrating the underlying molecular mechanisms and signaling pathways supporting VM in HCC. In this review, we summarize the correlation between epithelial-mesenchymal transition (EMT), cancer stem cells (CSCs) and VM, the role of hypoxia and extracellular matrix remodeling in VM, the involvement of adjacent non-cancerous cells, cytokines and growth factors in VM, as well as the regulatory influence of non-coding RNAs on VM in HCC. Moreover, we discuss the clinical significance of VM in practice and the potential therapeutic strategies targeting VM for HCC. A better understanding of the mechanism underlying VM formation in HCC may optimize anti-angiogenic treatment modalities for HCC.

Cancer Stem Cells-Key Players in Tumor Relapse

Tumor relapse and treatment failure are unfortunately common events for cancer patients, thus often rendering cancer an uncurable disease. Cancer stem cells (CSCs) are a subset of cancer cells endowed with tumor-initiating and self-renewal capacity, as well as with high adaptive abilities. Altogether, these features contribute to CSC survival after one or multiple therapeutic approaches, thus leading to treatment failure and tumor progression/relapse. Thus, elucidating the molecular mechanisms associated with stemness-driven resistance is crucial for the development of more effective drugs and durable responses. This review will highlight the mechanisms exploited by CSCs to overcome different therapeutic strategies, from chemo- and radiotherapies to targeted therapies and immunotherapies, shedding light on their plasticity as an insidious trait responsible for their adaptation/escape. Finally, novel CSC-specific approaches will be described, providing evidence of their preclinical and clinical applications.

Mechanisms of vasculogenic mimicry in hypoxic tumor microenvironments

Background

Vasculogenic mimicry (VM) is a recently discovered angiogenetic process found in many malignant tumors, and is different from the traditional angiogenetic process involving vascular endothelium. It involves the formation of microvascular channels composed of tumor cells; therefore, VM is considered a new model for the formation of new blood vessels in aggressive tumors, and can provide blood supply for tumor growth. Many studies have pointed out that in recent years, some clinical treatments against angiogenesis have not been satisfactory possibly due to the activation of VM. Although the mechanisms underlying VM have not been fully elucidated, increasing research on the soil “microenvironment” for tumor growth suggests that the initial hypoxic environment in solid tumors is inseparable from VM.

Main body

In this review, we describe that the stemness and differentiation potential of cancer stem cells are enhanced under hypoxic microenvironments, through hypoxia-induced epithelial-endothelial transition (EET) and extracellular matrix (ECM) remodeling to form the specific mechanism of vasculogenic mimicry; we also summarized some of the current drugs targeting VM through these processes, suggesting a new reference for the clinical treatment of tumor angiogenesis.

Conclusion

Overall, the use of VM inhibitors in combination with conventional anti-angiogenesis treatments is a promising strategy for improving the effectiveness of targeted angiogenesis treatments; further, considering the importance of hypoxia in tumor invasion and metastasis, drugs targeting the hypoxia signaling pathway seem to achieve good results.

Extracellular Vesicles Are Key Regulators of Tumor Neovasculature

Tumor progression involves a series of biologically important steps in which the crosstalk between cancer cells and the surrounding environment is an important issue. Angiogenesis is a key tumorigenic phenomenon for cancer progression. Tumor-related extracellular vesicles (EVs) modulate the tumor microenvironment (TME) through cell-to-cell communication. Tumor cells in a hypoxic TME release more EVs than cells in a normoxic environment due to uncontrollable tumor proliferation. Tumor-derived EVs in the TME influence endothelial cells (ECs), which then play multiple roles, contributing to tumor angiogenesis, loss of the endothelial vascular barrier by binding to ECs, and subsequent endothelial-to-mesenchymal transition. In contrast, they also indirectly induce tumor angiogenesis through the phenotype switching of various cells into cancer-associated fibroblasts, the activation of tumor-associated ECs and platelets, and remodeling of the extracellular matrix. Here, we review current knowledge regarding the involvement of EVs in tumor vascular-related cancer progression.

CD276 Promotes Vasculogenic Mimicry Formation in Hepatocellular Carcinoma via the PI3K/AKT/MMPs Pathway

Purpose

CD276 protein expression and vasculogenic mimicry (VM) formation are associated with the poor prognosis of hepatocellular carcinoma (HCC) patients. Although both the effects of CD276 and VM formation involve the activation of matrix metalloproteinases, and their relationship has not yet been explored. The following study investigated the effect of CD276 expression on VM formation and the potential mechanisms.

Materials and Methods

CD276 expression and VM were examined in commercial tissue microarrays by immunohistochemistry and CD31/PAS double staining. Tumor cell proliferation, invasion, migration and, tube formation were detected in vitro after transfecting HCC cell lines with an shRNA lentiviral vector against CD276. The expression of MMP14, MMP2, VE-cadherin, E-cadherin, and vimentin and MMPs activation was detected by Western blot, immunofluorescence and gelatin zymography assay. In addition, an orthotopic xenograft model of HCC cells was established in vivo, after which VM was detected, along with its marker molecules.

Results

CD276 expression was associated with VM and poor prognosis in HCC patients. RNA interference of CD276 reduced tumor cell proliferation, invasion, migration, and VM formation in vitro and in vivo. Furthermore, CD276 knockdown up-regulated the expression of E-cadherin but inhibited the phosphorylation of AKT, the expression of MMP14, MMP2, VE-cadherin, vimentin and the activation of MMP2 and MMP9 in HCC cell lines.

Conclusion

CD276 may promote VM formation by activating the PI3K/AKT/MMPs pathway and inducing the EMT process in HCC. CD276 may serve as a promising candidate for the anti-VM treatment of HCC.

The MSC-MCF-7 Duet Playing Tumor Vasculogenesis and Angiogenesis onto the Chick Embryo Chorioallantoic Membrane

BACKGROUND/AIM

Human mesenchymal stem cells (hMSC) represent a versatile cell population, able to modulate the tumor microenvironment. Our aim was to recreate an open scene for the in vivo interaction between hMSC and the MCF-7 breast cancer cells (MCF-7), in order to enlighten the intimate involvement of hMSC in tumor vasculogenesis and angiogenesis.

MATERIALS AND METHODS

hMSC and MCF-7 were seeded onto the chick embryo chorioallantoic membrane (CAM) and incubated for 7 days. Consecutively, the morphology and the immunohistochemical profile of CAM were assessed.

RESULTS

Following this complex interaction, MCF-7 acquired a more aggressive phenotype, hMSC switched to a vascular precursor phenotype, while CAM underwent a major reset to an earlier stage, with hotspots of angiogenesis, vasculogenesis and hematopoiesis.

CONCLUSION

The hallmark of this study was the establishment of a veritable in vivo experimental model of MSC involvement in tumor vasculogenesis and angiogenesis, allowing further analysis in the field.

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.

Morphological Characteristics and Clinical Significance of Different Types of Tumor Vessels in Patients with Stages I-IIA of Squamous Cervical Cancer

The determination of factors associated with progression of cervical cancer is important, both for a recurrence risk assessment and for determining optimal treatment tactics. Previously, we showed the prognostic value of different types of tumor microvessels (MVs) in gastric and breast cancer. The object of this research was to study the morphology and clinical significance of different tumor microvessels in early cervical cancer. A total of 65 archived paraffin blocks of patients with I-IIA stages of squamous cervical cancer were investigated. Samples were stained with Mayer hematoxylin and immunohistochemically using antibodies to CD34, podoplanin, HIF-1a, and Snail. The eight types of tumor MVs differed in morphology were identified. It was established that only the dilated capillaries (DСs) with weak expression of CD34, the contact type DCs, the capillaries in tumor solid component, and the lymphatic vessels in the lymphoid and polymorphic cell infiltrates of tumor stroma are associated with clinical and pathological characteristics of early cervical cancer. Preliminary results also suggest that a combination of fragmentation in tumor solid component and the contact type DCs may predict a recurrence of early cervical cancer. Given the small number of cervical cancer recurrences, the predictive significance of the described markers requires a more thorough examination.