An antiestrogen-binding protein in human tissues

Vascular disrupting agents in cancer therapy

Tumor blood vessel formation is a key process for tumor expansion. Tumor vessels are abnormal and differ from normal vessels in architecture and components. Besides oxygen and nutrients supply, the tumor vessels system, due to its abnormality, is responsible for: hypoxia formation, and metastatic routes. Tumor blood vessels can be a target of anti-cancer therapies. There are two types of therapies that target tumor vessels. The first one is the inhibition of the angiogenesis process. However, the inhibition is often ineffective because of alternative angiogenesis mechanism activation. The second type is a specific targeting of existing tumor blood vessels by vascular disruptive agents (VDAs). There are three groups of VDAs: microtubule destabilizing drugs, flavonoids with anti-vascular functions, and tumor vascular targeted drugs based on endothelial cell receptors. However, VDAs possess some limitations. They may be cardiotoxic and their application in therapy may leave viable residual, so called, rim cells on the edge of the tumor. However, it seems that a well-designed combination of VDAs with other anti-cancer drugs may bring a significant therapeutic effect. In this article, we describe three groups of vascular disruptive agents with their advantages and disadvantages. We mention VDAs clinical trials. Finally, we present the current possibilities of VDAs combination with other anti-cancer drugs.

Tumor Endothelial Cells (TECs) as Potential Immune Directors of the Tumor Microenvironment - New Findings and Future Perspectives

The tumor microenvironment (TME) plays a central role in cancer development and progression. It represents a complex network of cancer cell (sub-)clones and a variety of stromal cell types. Recently, new technology platforms shed light on the cellular composition of the TME at very high resolution and identified a complex landscape of multi-lineage immune cells (e.g., T and B lymphocytes, myeloid cells, and dendritic cells), cancer associated fibroblasts (CAF) and tumor endothelial cells (TECs). A growing body of evidence suggests that metabolically, genetically and on their transcriptomic profile TECs exhibit unique phenotypic and functional characteristics when compared to normal endothelial cells (NECs). Furthermore, the functional role of TECs is multifaceted as they are not only relevant for promoting tumor angiogenesis but have also evolved as key mediators of immune regulation in the TME. Regulatory mechanisms are complex and profoundly impact peripheral immune cell trafficking into the tumor compartment by acting as major gatekeepers of cellular transmigration. Moreover, TECs are associated with T cell priming, activation and proliferation by acting as antigen-presenting cells themselves. TECs are also essential for the formation of tertiary lymphoid structures (TLS) within the tumor, which have recently been associated with treatment response to checkpoint antibody therapy. Further essential characteristics of TECs compared to NECs are their high proliferative potential as well as greatly altered gene expression profile (e.g., upregulation of pro-angiogenic, extracellular matrix remodeling, and stemness genes), which results in enhanced secretion of immunomodulatory cytokines and altered cell-surface receptors [e.g., major histocompatibility complex (MHC) and immune checkpoints]. The TEC phenotype may be rooted in an aggressive tumor micro-milieu based on cellular stress via hypoxia and reactive oxygen species (ROS). Vice versa TECs might modulate TME immunogenicity thereby fostering cancer-associated immune suppression. This review aims to elucidate the currently emergent pathophysiological aspects of TECs with a particular focus on their potential role as regulators of immune cell function in the TME. It is a main future challenge to deeply characterize the phenotypic and functional profile of TECs to illuminate their complex role within the TME. The ultimate goal is the identification of TEC-specific drug targets to improve cancer (immuno-)therapy.

Endothelial-to-Mesenchymal Transition in Cancer

Cancer is one of the most important causes of morbidity and mortality worldwide. Tumor cells grow in a complex microenvironment constituted of immune, stromal, and vascular cells that supports growth, angiogenesis, and metastasis. Endothelial cells (ECs) are major components of the vascular microenvironment. These cells have been described for their plasticity and potential to transdifferentiate into mesenchymal cells through a process known as endothelial-to-mesenchymal transition (EndMT). This complex process is controlled by various factors, by which ECs convert into a phenotype characterized by mesenchymal protein expression and motile, contractile morphology. Initially described in normal heart development, EndMT is now identified in several pathologies, and especially in cancer. In this review, we highlight the process of EndMT in the context of cancer and we discuss it as an important adaptive process of the tumor microenvironment that favors tumor growth and dissemination but also resistance to treatment. Thus, we underline targeting of EndMT as a potential therapeutic strategy.

The tumour microenvironment and metabolism in renal cell carcinoma targeted or immune therapy

Renal cell carcinoma (RCC) is one of the most common tumours of the urinary system, and is insidious and not susceptible to chemoradiotherapy. As the most common subtype of RCC (70-80% of cases), clear cell renal cell carcinoma (ccRCC) is characterized by the loss of von Hippel-Lindau and the accumulation of robust lipid and glycogen. For advanced RCC, molecular-targeted drugs, tyrosine kinase inhibitors (TKIs) and the immune checkpoint inhibitors (ICIs) have been increasingly recommended and investigated. Due to the existence of a highly dynamic, adaptive and heterogeneous tumour microenvironment (TME), and due to the glucose and lipid metabolism in RCC, this cancer may be accompanied by various types of resistance to TKIs and ICIs. With the increased production of lactate, nitric oxide, and other new by-products of metabolism, novel findings of the TME and key metabolic enzymes drived by HIF and other factors have been increasingly clarified in RCC carcinogenesis and therapy. However, there are few summaries of the TME and tumour metabolism for RCC progression and therapy. Here, we summarize and discuss the relationship of the important implicated characteristics of the TME as well as metabolic molecules and RCC carcinogenesis to provide prospects for future treatment strategies to overcome TME-related resistance in RCC.

Extracellular Vesicle Transfer from Endothelial Cells Drives VE-Cadherin Expression in Breast Cancer Cells, Thereby Causing Heterotypic Cell Contacts

Cadherins mediate cohesive contacts between isotypic cells by homophilic interaction and prevent contact between heterotypic cells. Breast cancer cells neighboring endothelial cells (ECs) atypically express vascular endothelial (VE)-cadherin. To understand this EC-induced VE-cadherin expression in breast cancer cells, MCF7 and MDA-MB-231 cells expressing different endogenous cadherins were co-cultured with ECs and analyzed for VE-cadherin at the transcriptional level and by confocal microscopy, flow cytometry, and immunoblotting. After losing their endogenous cadherins and neo-expression of VE-cadherin, these cells integrated into an EC monolayer without compromising the barrier function instantly. However, they induced the death of nearby ECs. EC-derived extracellular vesicles (EVs) contained soluble and membrane-anchored forms of VE-cadherin. Only the latter was re-utilized by the cancer cells. In a reporter gene assay, EC-adjacent cancer cells also showed a juxtacrine but no paracrine activation of the endogenous VE-cadherin gene. This cadherin switch enabled intimate contact between cancer and endothelial cells in a chicken chorioallantoic membrane tumor model showing vasculogenic mimicry (VM). This EV-mediated, EC-induced cadherin switch in breast cancer cells and the neo-expression of VE-cadherin mechanistically explain the mutual communication in the tumor microenvironment. Hence, it may be a target to tackle VM, which is often found in breast cancers of poor prognosis.

Resistance to Anti-angiogenic Therapies: A Mechanism Depending on the Time of Exposure to the Drugs

Angiogenesis, the formation of new blood vessels from preexisting one, represents a critical process for oxygen and nutrient supply to proliferating cells, therefore promoting tumor growth and metastasis. The Vascular Endothelial Growth Factor (VEGF) pathway is one of the key mediators of angiogenesis in cancer. Therefore, several therapies including monoclonal antibodies or tyrosine kinase inhibitors target this axis. Although preclinical studies demonstrated strong antitumor activity, clinical studies were disappointing. Antiangiogenic drugs, used to treat metastatic patients suffering of different types of cancers, prolonged survival to different extents but are not curative. In this review, we focused on different mechanisms involved in resistance to antiangiogenic therapies from early stage resistance involving mainly tumor cells to late stages related to the adaptation of the microenvironment.

SM22α+ vascular mural cells are essential for vessel stability in tumors and undergo phenotype transition regulated by Notch signaling

Background

Malformation of blood vessels represents a hallmark of cancers, but the role and regulation of vascular mural cells (vMCs), including vascular smooth muscle cells (vSMCs) and pericytes, in tumors has not been fully understood. SM22α has been identified as a marker of vSMCs. This study aims at elucidating the function and regulation of SM22α⁺ mural cells (SM22-MCs) in tumor stroma.

Methods

Gene-modified mice with a SM22α-CreER^T2 transgene were employed to deplete SM22-MCs or activate/block Notch signaling in these cells. vSMCs from mouse dorsal aorta (vSMCs-DA) were cultured in vitro. RNA-seq was used to compare gene expression profiles. qRT-PCR and western blotting were used to determine gene expression level. Immunofluorescence was used to observe morphological alterations in tumors.

Results

SM22-MCs are essential for stabilizing tumor vasculature. Notch signaling was downregulated in tumor-derived SM22-MCs and vSMCs-DA treated with cancer cell-derived conditioned medium. Notch activation in SM22-MCs normalized tumor vasculature and repressed tumor growth. On the other hand, Notch disruption aggravated abnormal tumor vasculature and promoted growth and metastasis. Gene expression profiling of vSMCs-DA showed that Notch activation enhances their contractile phenotype and suppresses their secretory phenotype, further attenuating the invasion and proliferation of tumor cells. In contrast, Notch blockade in vSMCs-DA mitigated their contractile phenotype while strengthened the secretory phenotype.

Conclusion

SM22-MCs facilitate vessel stability in tumors, and they gain a secretory phenotype and promote tumor malignancy in the absence of Notch signaling.

Antineoplastic drug-loaded polymer-modified magnetite nanoparticles: Comparative analysis of EPR-mediated drug delivery

This study aimed to design and evaluate enhanced permeation and retention (EPR)-mediated anticancer effect of polymer-modified and drug-loaded magnetite nanocomposites. The preformulated bare (10 nm), chitosan-superparamagnetic iron oxide (SPIO; 69 nm), heparin-SPIO (42 nm), and (3-aminopropyl)triethoxysilane-polyethylene glycol-SPIO (17 nm) nanocomposites were utilized to evaluate the EPR-mediated localized cancer targeting and retention of doxorubicin (DOX) and paclitaxel (PTX) in human ovarian cancer cell lines, A2780 and OVCAR-3 in vitro and in the tumor-baring Balb/c mice in vivo. Fluorescence microscopy showed that DOX- and PTX-loaded SPIO nanoparticles caused long-term accumulation and cytoplasmic retention in A2780 and OVCAR-3 cells, as compared to free drugs in vitro. In vivo antiproliferative effect of present formulations on immunodeficient female Balb/c mice showed a tremendous amount of ovarian tumor shrinkage within 6 weeks. The present nanocomposite systems of targeted drug delivery proved to be efficient drug carrier with sustained drug release and long-term retention with enhanced cytotoxic properties in vitro and in vivo.

Dl-3-n-Butylphthalide promotes neovascularization and neurological recovery in a rat model of intracerebral hemorrhage

Background

Cerebral stroke occurs following ischemic and hemorrhagic lesions in the brain. Survival and recovery of stroke patients depend on the severity of the initial injury but also the therapeutic approaches applied for emergent lifesaving and continuing post-stroke management. Dl-3-n-Butylphthalide (NBP), an active compound derived from Chinese celery seeds, has shown clinical efficacy in the treatment of ischemic cerebral stroke.

Results

In the present study we explored the therapeutic effect of NBP in a rat model of intracerebral hemorrhage (ICH), focusing on its potential role in promoting neovascularization in the perihemorrhagic zone. ICH was induced in male Sprague-Dawley rats by unilateral injection of autologous blood into the globus pallidus, with sham-operated (Sham group), vehicle-treated (ICH) and NBP-treated (at 10 and 25 mg/kg/Bid, p.o., ICH + NBP10 and ICH + NBP25, respectively) groups examined behaviorally, macroscopically, histologically and biochemically at 1, 3, 7 and 15 days (d) post operation. Rats in the ICH + NBP10 and ICH + NBP25 groups showed reduced Longa’s motor scores relative to the ICH groups at the 3 and 7d time points, while the hematoma volume was comparable in the two NBP relative to the ICH groups as measured at 7d and 15d. In the perihemorrhagic zone, the numeric density of blood vessels immunolabeled by CD34, an angiogenic marker, was greater in the ICH + NBP10 and ICH + NBP25 than ICH groups, more so in the higher dosage group, at 1, 3, 7 and 15d. Levels of the vascular endothelial growth factor (VEGF) and angiopoietins-2 (Ang-2) proteins were elevated in the NBP groups relative to the sham and vehicle controls in immunoblotting of tissue lysates from the injection region.

Conclusion

These results suggest that NBP can alleviate neurological defects following experimentally induced local brain hemorrhage, which is associated with a potential role of this drug in promoting neovascularization surrounding the bleeding loci.

Tumor Endothelial Cell-A Biological Tool for Translational Cancer Research

Going from bench to bedside is a simplified description of translational research, with the ultimate goal being to improve the health status of mankind. Tumor endothelial cells (TECs) perform angiogenesis to support the growth, establishment, and dissemination of tumors to distant organs. TECs have various features that distinguish them from normal endothelial cells, which include alterations in gene expression patterns, higher angiogenic and metabolic activities, and drug resistance tendencies. The special characteristics of TECs enhance the vulnerability of tumor blood vessels toward antiangiogenic therapeutic strategies. Therefore, apart from being a viable therapeutic target, TECs would act as a better mediator between the bench (i.e., angiogenesis research) and the bedside (i.e., clinical application of drugs discovered through research). Exploitation of TEC characteristics could reveal unidentified strategies of enhancing and monitoring antiangiogenic therapy in the treatment of cancer, which are discussed in this review.

The Epigenetic Profile of Tumor Endothelial Cells. Effects of Combined Therapy with Antiangiogenic and Epigenetic Drugs on Cancer Progression

Tumors require a constant supply of nutrients to grow which are provided through tumor blood vessels. To metastasize, tumors need a route to enter circulation, that route is also provided by tumor blood vessels. Thus, angiogenesis is necessary for both tumor progression and metastasis. Angiogenesis is tightly regulated by a balance of angiogenic and antiangiogenic factors. Angiogenic factors of the vascular endothelial growth factor (VEGF) family lead to the activation of endothelial cells, proliferation, and neovascularization. Significant VEGF-A upregulation is commonly observed in cancer cells, also due to hypoxic conditions, and activates endothelial cells (ECs) by paracrine signaling stimulating cell migration and proliferation, resulting in tumor-dependent angiogenesis. Conversely, antiangiogenic factors inhibit angiogenesis by suppressing ECs activation. One of the best-known anti-angiogenic factors is thrombospondin-1 (TSP-1). In pathological angiogenesis, the balance shifts towards the proangiogenic factors and an angiogenic switch that promotes tumor angiogenesis. Here, we review the current literature supporting the notion of the existence of two different endothelial lineages: normal endothelial cells (NECs), representing the physiological form of vascular endothelium, and tumor endothelial cells (TECs), which are strongly promoted by the tumor microenvironment and are biologically different from NECs. The angiogenic switch would be also important for the explanation of the differences between NECs and TECs, as angiogenic factors, cytokines and growth factors secreted into the tumor microenvironment may cause genetic instability. In this review, we focus on the epigenetic differences between the two endothelial lineages, which provide a possible window for pharmacological targeting of TECs.