Is angiogenesis essential for the progression of hematological malignancies or is it an epiphenomenon?

Tumor-Associated Macrophages and Related Myelomonocytic Cells in the Tumor Microenvironment of Multiple Myeloma

Multiple myeloma (MM) is the second-most common hematologic malignancy and remains incurable despite potent plasma cell directed therapeutics. The tumor microenvironment (TME) is a key player in the pathogenesis and progression of MM and is an active focus of research with a view to targeting immune dysregulation. Tumor-associated macrophages (TAM), myeloid derived suppressor cells (MDSC), and dendritic cells (DC) are known to drive progression and treatment resistance in many cancers. They have also been shown to promote MM progression and immune suppression in vitro, and there is growing evidence of their impact on clinical outcomes. The heterogeneity and functional characteristics of myelomonocytic cells in MM are being unraveled through high-dimensional immune profiling techniques. We are also beginning to understand how they may affect and be modulated by current and future MM therapeutics. In this review, we provide an overview of the biology and clinical relevance of TAMs, MDSCs, and DCs in the MM TME. We also highlight key areas to be addressed in future research as well as our perspectives on how the myelomonocytic compartment of the TME may influence therapeutic strategies of the future.

Exosome as a target for cancer treatment

Exosomes are small vesicles covered by a lipid bilayer, ranging in size from 50 nm to 90 nm, secreted by different cell types in the body under normal and pathological conditions. They are surrounded by cell-segregated membrane complexes and play a role in the pathological and physiological environments of target cells by transfer of different molecules such as microRNA (miRNA). Exosomes have been detected in many body fluids, such as in the amniotic fluid, urine, breast milk, blood, saliva, ascites, semen, and bile. They include proteins, lipids, and nucleic acids such as DNA, RNA, and miRNA, which have many functions in target cells under pathological and physiological conditions. They participate in pathological processes such as tumor growth and survival, autoimmunity, neurodegenerative disorders, infectious diseases, inflammation conditions, and others. Biomarkers in exosomes isolated from body fluids have allowed for a more precise and consistent diagnostic method than previous approaches. Exosomes can be used in a variety of intracellular functions, and with advances in molecular techniques they can be used in the treatment and diagnosis of many diseases, including cancer. These vesicles play a significant role in various stages of cancer. Tumor-derived exosomes have an important role in tumor growth, survival, and metastasis. In contrast, the use of stem cells in cancer treatment is a relatively new scientific area. We hope to address targeted use of miRNA-carrying exosomes in cancer therapy in this review paper.

Improving cancer treatments via dynamical biophysical models

Despite significant advances in oncological research, cancer nowadays remains one of the main causes of mortality and morbidity worldwide. New treatment techniques, as a rule, have limited efficacy, target only a narrow range of oncological diseases, and have limited availability to the general public due their high cost. An important goal in oncology is thus the modification of the types of antitumor therapy and their combinations, that are already introduced into clinical practice, with the goal of increasing the overall treatment efficacy. One option to achieve this goal is optimization of the schedules of drugs administration or performing other medical actions. Several factors complicate such tasks: the adverse effects of treatments on healthy cell populations, which must be kept tolerable; the emergence of drug resistance due to the intrinsic plasticity of heterogeneous cancer cell populations; the interplay between different types of therapies administered simultaneously. Mathematical modeling, in which a tumor and its microenvironment are considered as a single complex system, can address this complexity and can indicate potentially effective protocols, that would require experimental verification. In this review, we consider classical methods, current trends and future prospects in the field of mathematical modeling of tumor growth and treatment. In particular, methods of treatment optimization are discussed with several examples of specific problems related to different types of treatment.

Organ-Chip Models: Opportunities for Precision Medicine in Pancreatic Cancer

Simple Summary

Among all types of cancer, Pancreatic Ductal Adenocarcinoma (PDAC) has one of the lowest survival rates, partly due to the failure of current chemotherapeutics. This treatment failure can be attributed to the complicated nature of the tumor microenvironment, where the rich fibro-inflammatory responses can hinder drug delivery and efficacy at the tumor site. Moreover, the high molecular variations in PDAC create a large heterogeneity in the tumor microenvironment among patients. Current in vivo and in vitro options for drug testing are mostly ineffective in recapitulating the complex cellular interactions and individual variations in the PDAC tumor microenvironment, and as a result, they fail to provide appropriate models for individualized drug screening. Organ-on-a-chip technology combined with patient-derived organoids may provide the opportunity for developing personalized treatment options in PDAC.

Abstract

Pancreatic Ductal Adenocarcinoma (PDAC) is an expeditiously fatal malignancy with a five-year survival rate of 6–8%. Conventional chemotherapeutics fail in many cases due to inadequate primary response and rapidly developing resistance. This treatment failure is particularly challenging in pancreatic cancer because of the high molecular heterogeneity across tumors. Additionally, a rich fibro-inflammatory component within the tumor microenvironment (TME) limits the delivery and effectiveness of anticancer drugs, further contributing to the lack of response or developing resistance to conventional approaches in this cancer. As a result, there is an urgent need to model pancreatic cancer ex vivo to discover effective drug regimens, including those targeting the components of the TME on an individualized basis. Patient-derived three-dimensional (3D) organoid technology has provided a unique opportunity to study patient-specific cancerous epithelium. Patient-derived organoids cultured with the TME components can more accurately reflect the in vivo tumor environment. Here we present the advances in organoid technology and multicellular platforms that could allow for the development of “organ-on-a-chip” approaches to recapitulate the complex cellular interactions in PDAC tumors. We highlight the current advances of the organ-on-a-chip-based cancer models and discuss their potential for the preclinical selection of individualized treatment in PDAC.

Mutated TP53 is a marker of increased VEGF expression: analysis of 7,525 pan-cancer tissues

Anti-angiogenic therapies are an important class of anti-cancer treatment drugs. However, their efficacy is limited to certain tumors and would benefit from identifying a biomarker predictive of therapeutic response. TP53 (tumor protein p53) is a tumor suppressor gene frequently mutated in cancer and implicated in cell-cycle regulation, apoptosis, and angiogenesis. Data from 7,525 unique tumor samples (representing 30 tumor cohorts) were retrieved from the TCGA database to analyze the relationship between TP53-mutation status and VEGFA (vascular endothelial growth factor A) expression. Univariate analyses were done using a Mann-Whitney univariate test or Fisher's exact test. Parameters with a p-value (p)≤0.1 in univariate analysis were selected for follow-up multivariate analyses, including TP53-mutation status, cancer cohorts, cancer subtypes, and VEGFA expression. Our analysis demonstrates statistically significant increases in VEGFA mRNA tissue expression in TP53-mutated adenocarcinomas (but not in squamous cancers) compared to TP53 wild-type tumors. This association holds true in multivariate analyses and remains independent of HIF-1α and MDM2 overexpression. Our findings provide additional evidence that TP53 mutations are linked to the VEGF pathway, potentially offering insight into the mechanism behind increased sensitivity to anti-angiogenic therapies observed in some TP53-mutant tumors.

CS2164 suppresses acute myeloid leukemia cell growth via inhibiting VEGFR2 signaling in preclinical models

Acute myeloid leukemia (AML) arises from neoplastic transformation of hematopoietic stem and progenitor cells, and resistance to conventional chemotherapy remains one of the greatest challenges in treating the disease. Extensive data have demonstrated that angiogenesis is associated with AML progression and chemotherapy resistance. Thus, targeting angiogenesis may be a promising approach for AML treatment. In this study, we investigated the effectiveness of CS2164 (named as Chiauranib), a novel receptor tyrosine kinase inhibitor, in AML cells. Our results illustrated that CS2164 significantly suppressed cell proliferation and abolished clonogenicity in AML cells in a dose- and time-dependent manner. Meanwhile, CS2164 markedly induced apoptosis of AML cell lines and primary AML cells from 42 adult patients. Furthermore, we found that CS2164 has a comprehensive activity against AML irrespective of disease status and genetic mutations. Also, CS2164 suppressed AML growth in xenograft models in vivo. Mechanistically, CS2164-induced cytotoxicity was closely associated with inhibition of VEGFR2 and its downstream signaling cascades, including Src/Fyn/p38 and Erk/MEK. In conclusion, our study indicates that CS2164 exerts anti-leukemia effect by inducing apoptosis through suppressing the VEGFR2 pathway, supporting a potential role for CS2164 in the treatment of AML.

Tissue engineered models of healthy and malignant human bone marrow

Tissue engineering is becoming increasingly successful in providing in vitro models of human tissues that can be used for ex vivo recapitulation of functional tissues as well as predictive testing of drug efficacy and safety. From simple tissue models to microphysiological platforms comprising multiple tissue types connected by vascular perfusion, these "tissues on a chip" are emerging as a fast track application for tissue engineering, with great potential for modeling diseases and supporting the development of new drugs and therapeutic targets. We focus here on tissue engineering of the hematopoietic stem and progenitor cell compartment and the malignancies that can develop in the human bone marrow. Our overall goal is to demonstrate the utility and interconnectedness of improvements in bioengineering methods developed in one area of bone marrow studies for the remaining, seemingly disparate, bone marrow fields.

The Angiogenic Chemokines Expression Profile of Myeloid Cell Lines Co-Cultured with Bone Marrow-Derived Mesenchymal Stem Cells

OBJECTIVES

Angiogenesis, the process of formation of new blood vessels, is essential for development of solid tumors. At first, it was first assumed that angiogenesis is not implicated in the development of acute myeloid leukemia (AML) as a liquid tumor. One of the most important elements in bone marrow microenvironment is mesenchymal stem cells (MSCs). These cells possess an intrinsic tropism for sites of tumor in various types of cancers and have an impact on solid tumors growth by affecting the angiogenic process. But so far, our knowledge is limited about MSCs' role in liquid tumors angiogenesis. By increasing our knowledge about the role of MSCs on angiogenesis, new therapeutic strategies can be used to improve the status of patients with leukemia.

MATERIALS AND METHODS

In this experimental study, HL-60, K562 and U937 cells were separately co-cultured with bone marrow derived-MSCs and after 8, 16 and 24 hours, alterations in the expression of 10 chemokine genes involved in angiogenesis, were evaluated by quantitative real time-polymerase chain reaction (qRT-PCR). Mono-cultures of leukemia cell lines were used as controls.

RESULTS

We observed that in HL-60 and K562 cells co-cultured with MSCs, the expression of CXCL10 and CXCL3 genes are increased, respectively as compared to the control cells. Also, in U937 cells co-cultured with MSCs, the expression of CXCL6 gene was upgraded. Moreover in U937 cells, CCL2 gene expression in the first 16 hours was lower than the control cells, while within 24 hours its expression augmented.

CONCLUSIONS

Our observations, for the first time, demonstrated that bone marrow (BM)-MSCs are able to alter the expression profile of chemokine genes involved in angiogenesis, in acute myeloid leukemia cell lines. MSCs cause different effects on angiogenesis in different leukemia cell lines; in some cases, MSCs promote angiogenesis, and in others, inhibit it.

A three-dimensional ex vivo tri-culture model mimics cell-cell interactions between acute myeloid leukemia and the vascular niche

Ex vivo studies of human disease, such as acute myeloid leukemia, are generally limited to the analysis of two-dimensional cultures which often misinterpret the effectiveness of chemotherapeutics and other treatments. Here we show that matrix metalloproteinase-sensitive hydrogels prepared from poly(ethylene glycol) and heparin functionalized with adhesion ligands and pro-angiogenic factors can be instrumental to produce robust three-dimensional culture models, allowing for the analysis of acute myeloid leukemia development and response to treatment. We evaluated the growth of four leukemia cell lines, KG1a, MOLM13, MV4-11 and OCI-AML3, as well as samples from patients with acute myeloid leukemia. Furthermore, endothelial cells and mesenchymal stromal cells were co-seeded to mimic the vascular niche for acute myeloid leukemia cells. Greater drug resistance to daunorubicin and cytarabine was demonstrated in three-dimensional cultures and in vascular co-cultures when compared with two-dimensional suspension cultures, opening the way for drug combination studies. Application of the C-X-C chemokine receptor type 4 (CXCR4) inhibitor, AMD3100, induced mobilization of the acute myeloid leukemia cells from the vascular networks. These findings indicate that the three-dimensional tri-culture model provides a specialized platform for the investigation of cell-cell interactions, addressing a key challenge of current testing models. This ex vivo system allows for personalized analysis of the responses of patients’ cells, providing new insights into the development of acute myeloid leukemia and therapies for this disease.

Angiogenesis in Liquid Tumors: An In Vitro Assay for Leukemic-Cell-Induced Bone Marrow Angiogenesis

The critical role of angiogenesis for solid tumor growth and metastatic spread has been well established. In contrast, even though increased vascularity has been commonly observed in bone marrows of patients with hematological malignancies (liquid tumors), the pathophysiology of leukemia-induced angiogenesis in the bone marrow remains elusive. This paper demonstrates the usage of a microengineered 3D biomimetic model to study leukemic-cell-induced bone marrow angiogenesis. Rational design of the 3D angiogenesis chip incorporating endothelial cells (ECs), leukemic cells, and bone marrow stromal fibroblasts provide an efficient biomimetic means to promote and visualize early angiogenic processes. Morphological features of angiogenesis induced by three different leukemic cell lines (U937, HL60, and K562) are investigated and compared. Quantitative measurements of angiogenic factors secreted from monocultures and cocultures of leukemic cells with bone marrow stromal fibroblasts suggest a synergistic relationship between ECs, leukemic cells, and bone marrow stromal fibroblasts for angiogenic induction, and also confirm the necessity of conducting functional angiogenic assays in proper 3D biomimetic cell culture systems like the one developed in this work.

Functional integration of acute myeloid leukemia into the vascular niche

Vascular endothelial cells are a critical component of the hematopoietic microenvironment that regulates blood cell production. Recent studies suggest the existence of functional cross-talk between hematologic malignancies and vascular endothelium. Here, we show that human acute myeloid leukemia (AML) localizes to the vasculature in both patients and in a xenograft model. A significant number of vascular tissue-associated AML cells (V-AML) integrate into vasculature in vivo and can fuse with endothelial cells. V-AML cells acquire several endothelial cell-like characteristics, including the up-regulation of CD105, a receptor associated with activated endothelium. Remarkably, endothelial-integrated V-AML shows an almost 4-fold reduction in proliferative activity compared to non-vascular associated AML. Primary AML cells can be induced to down regulate the expression of their hematopoietic markers in vitro and differentiate into phenotypically and functionally-defined endothelial-like cells. After transplantation, these leukemia-derived endothelial cells are capable of giving rise to AML. Taken together, these novel functional interactions between AML cells and normal endothelium along with the reversible endothelial cell potential of AML suggest that vascular endothelium may serve as a previously unrecognized reservoir for acute myeloid leukemia.

Angiogenesis as a treatment target in leukemia

SUMMARY The importance of angiogenesis in the growth and survival of leukemia has been well established and confirmed by several studies. In the last 20 years, several antiangiogenic agents have been used in preclinical and clinical studies of the treatment of leukemia. This review article summarizes the literature focusing on the relationship between angiogenesis and disease progression, and the advantages and limits of the antiangiogenic treatment of leukemia.

Anticancer Role of PPARgamma Agonists in Hematological Malignancies Found in the Vasculature, Marrow, and Eyes

The use of targeted cancer therapies in combination with conventional chemotherapeutic agents and/or radiation treatment has increased overall survival of cancer patients. However, longer survival is accompanied by increased incidence of comorbidities due, in part, to drug side effects and toxicities. It is well accepted that inflammation and tumorigenesis are linked. Because peroxisome proliferator-activated receptor (PPAR)-gamma agonists are potent mediators of anti-inflammatory responses, it was a logical extension to examine the role of PPARgamma agonists in the treatment and prevention of cancer. This paper has two objectives: first to highlight the potential uses for PPARgamma agonists in anticancer therapy with special emphasis on their role when used as adjuvant or combined therapy in the treatment of hematological malignancies found in the vasculature, marrow, and eyes, and second, to review the potential role PPARgamma and/or its ligands may have in modulating cancer-associated angiogenesis and tumor-stromal microenvironment crosstalk in bone marrow.

Contribution of bone microenvironment to leukemogenesis and leukemia progression

Tumor microenvironment has a major role in cancer progression and resistance to treatment. The bone marrow (BM) is a dynamic network of growth factors, cytokines and stromal cells, providing a permissive environment for leukemogenesis and progression. Both BM stroma and leukemic blasts promote angiogenesis, which is increased in acute lymphoblastic leukemia and acute myeloid leukemia. Growth factors like vascular endothelial growth factor (VEGF), basic fibroblast growth factor and angiopoietins are the main proangiogenic mediators in acute leukemia. Autocrine proleukemic loops have been described for VEGF and angiopoietin in hematopoietic cells. Interactions of stromal cells and extracellular matrix with leukemic blasts can also generate antiapoptotic signals that contribute to neoplastic progression and persistence of treatment-resistant minimal residual disease. High expression of CXC chemokine ligand 4 (CXCR4) by leukemic blasts and activation of the CXCR4-CXCL12 axis is involved in leukemia progression and disruption of normal hematopoiesis. Leukemia-associated bone microenvironment markers could be used as prognostic or predictive indicators of disease progression and/or treatment outcome. Studies related to bone microenvironment would likely provide a better understanding of the treatment resistance associated with leukemia therapy and design of new treatments.