Cell adhesion to collagen promotes leukemia resistance to doxorubicin by reducing DNA damage through the inhibition of Rac1 activation

Brain-Decellularized ECM-Based 3D Myeloid Sarcoma Platform: Mimicking Adaptive Phenotypic Alterations in the Brain

Leukemia circulates in the bloodstream and induces various symptoms and complications. Occasionally, these cells accumulate in non-marrow tissues, forming a tumor-like myeloid sarcoma (MS). When the blast-stage leukemia cells invade the brain parenchyma, intracranial MS occurs, leading to a challenging prognosis owing to the limited penetration of cytostatic drugs into the brain and the development of drug resistance. The scarcity of tissue samples from MS makes understanding the phenotypic changes occurring in leukemia cells within the brain environment challenging, thereby hindering development of effective treatment strategies for intracranial MS. This study presents a novel 3D in vitro model mimicking intracranial MS, employing a hydrogel scaffold derived from the brain-decellularized extracellular matrix in which suspended leukemia cells are embedded, simulating the formation of tumor masses in the brain parenchyma. This model reveals marked phenotypic changes in leukemia cells, including altered survival, proliferation, differentiation, and cell cycle regulation. Notably, proportion of dormant leukemia stem cells increases and expression of multidrug resistance genes is upregulated, leading to imatinib resistance, mirroring the pathological features of in vivo MS tissue. Furthermore, suppression of ferroptosis is identified as an important characteristic of intracranial MS, providing valuable insights for the development of targeted therapeutic strategies.

Targeting integrins in drug-resistant acute myeloid leukaemia

Acute myeloid leukaemia (AML) continues to have a poor prognosis, warranting new therapeutic strategies. The bone marrow (BM) microenvironment consists of niches that interact with not only normal haematopoietic stem cells (HSC) but also leukaemia cells like AML. There are many adhesion molecules in the BM microenvironment; therein, integrins have been of central interest. AML cells express integrins that bind to ligands in the microenvironment, enabling adhesion of leukaemia cells in the microenvironment, thereby initiating intracellular signalling pathways that are associated with cell migration, cell proliferation, survival, and drug resistance that has been described to mediate cell adhesion-mediated drug resistance (CAM-DR). Identifying and targeting integrins in AML to interrupt interactions with the microenvironment have been pursued as a strategy to overcome CAM-DR. Here, we focus on the BM microenvironment and review the role of integrins in CAM-DR of AML and discuss integrin-targeting strategies. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Bone Marrow Microenvironment-Induced Chemoprotection in KMT2A Rearranged Pediatric AML Is Overcome by Azacitidine-Panobinostat Combination

Advances in therapies of pediatric acute myeloid leukemia (AML) have been minimal in recent decades. Although 82% of patients will have an initial remission after intensive therapy, approximately 40% will relapse. KMT2A is the most common chromosomal translocation in AML and has a poor prognosis resulting in high relapse rates and low chemotherapy efficacy. Novel targeted approaches are needed to increase sensitivity to chemotherapy. Recent studies have shown how interactions within the bone marrow (BM) microenvironment help AML cells evade chemotherapy and contribute to relapse by promoting leukemic blast survival. This study investigates how DNA hypomethylating agent azacitidine and histone deacetylase inhibitor panobinostat synergistically overcome BM niche-induced chemoprotection modulated by stromal, endothelial, and mesenchymal stem cells and the extracellular matrix (ECM). We show that direct contact between AML cells and BM components mediates chemoprotection. We demonstrate that azacitidine and panobinostat synergistically sensitize MV4;11 cells and KMT2A rearranged pediatric patient-derived xenograft lines to cytarabine in multicell coculture. Treatment with the epigenetic drug combination reduced leukemic cell association with multicell monolayer and ECM in vitro and increased mobilization of leukemic cells from the BM in vivo. Finally, we show that pretreatment with the epigenetic drug combination improves the efficacy of chemotherapy in vivo.

Blockade of integrin signaling reduces chemotherapy-induced premature senescence in collagen cultured bladder cancer cells

Background

Diminished sensitivity towards chemotherapy remains the major impediment to the clinical treatment of bladder cancer. However, the critical elements in control of chemotherapy resistance remain obscure.

Methods

We adopted improved collagen gels and performed cytotoxicity analysis of doxorubicin (DOX) and mitomycin C (MMC) of bladder cancer cells in a 3D culture system. We then detected the expression of multidrug resistant gene ABCB1, dormancy-associated functional protein chicken ovalbumin upstream-transcription factor 1 (COUPTF1), cell proliferation marker Ki-67, and cellular senescence marker senescence-associated β-galactosidase (SA-β-Gal) in these cells. We further tested the effects of integrin blockade or protein kinase B (AKT) inhibitor on the senescent state of bladder cancer. Also, we examined the tumor growth and survival time of bladder cancer mouse models given the combination treatment of chemotherapeutic agents and integrin α2β1 ligand peptide TFA (TFA).

Results

Collagen gels played a repressive role in bladder cancer cell apoptosis induced by DOX and MMC. In mechanism, collagen activated the integrin β1/AKT cascade to drive bladder cancer cells into a premature senescence state via the p21/p53 pathway, thus attenuating chemotherapy-induced apoptosis. In addition, TFA had the ability to mediate the switch from senescence to apoptosis of bladder cancer cells in xenograft mice. Meanwhile, TFA combined with chemotherapeutic drugs produced a substantial suppression of tumor growth as well as an extension of survival time in vivo.

Conclusions

Based on our finding that integrin β1/AKT acted primarily to impart premature senescence to bladder cancer cells cultured in collagen gel, we suggest that integrin β1 might be a feasible target for bladder cancer eradication.

Adhesion Molecules Involved in Stem Cell Niche Retention During Normal Haematopoiesis and in Acute Myeloid Leukaemia

In the bone marrow (BM) of adult mammals, haematopoietic stem cells (HSCs) are retained in micro-anatomical structures by adhesion molecules that regulate HSC quiescence, proliferation and commitment. During decades, researchers have used engraftment to study the function of adhesion molecules in HSC's homeostasis regulation. Since the 90's, progress in genetically engineered mouse models has allowed a better understanding of adhesion molecules involved in HSCs regulation by BM niches and raised questions about the role of adhesion mechanisms in conferring drug resistance to cancer cells nested in the BM. This has been especially studied in acute myeloid leukaemia (AML) which was the first disease in which the concept of cancer stem cell (CSC) or leukemic stem cells (LSCs) was demonstrated. In AML, it has been proposed that LSCs propagate the disease and are able to replenish the leukemic bulk after complete remission suggesting that LSC may be endowed with drug resistance properties. However, whether such properties are due to extrinsic or intrinsic molecular mechanisms, fully or partially supported by molecular crosstalk between LSCs and surrounding BM micro-environment is still matter of debate. In this review, we focus on adhesion molecules that have been involved in HSCs or LSCs anchoring to BM niches and discuss if inhibition of such mechanism may represent new therapeutic avenues to eradicate LSCs.

Linking Oxidative Stress and DNA Damage to Changes in the Expression of Extracellular Matrix Components

Cells are subjected to endogenous [e.g., reactive oxygen species (ROS), replication stress] and exogenous insults (e.g., UV light, ionizing radiation, and certain chemicals), which can affect the synthesis and/or stability of different macromolecules required for cell and tissue function. Oxidative stress, caused by excess ROS, and DNA damage, triggered in response to different sources, are countered and resolved by specific mechanisms, allowing the normal physiological equilibrium of cells and tissues to be restored. One process that is affected by oxidative stress and DNA damage is extracellular matrix (ECM) remodeling, which is a continuous and highly controlled mechanism that allows tissues to readjust in reaction to different challenges. The crosstalk between oxidative stress/DNA damage and ECM remodeling is not unidirectional. Quite on the contrary, mutations in ECM genes have a strong impact on tissue homeostasis and are characterized by increased oxidative stress and potentially also accumulation of DNA damage. In this review, we will discuss how oxidative stress and DNA damage affect the expression and deposition of ECM molecules and conversely how mutations in genes encoding ECM components trigger accumulation of oxidative stress and DNA damage. Both situations hamper the reestablishment of cell and tissue homeostasis, with negative impacts on tissue and organ function, which can be a driver for severe pathological conditions.

CAM-DR: Mechanisms, Roles and Clinical Application in Tumors

Despite the continuous improvement of various therapeutic techniques, the overall prognosis of tumors has been significantly improved, but malignant tumors in the middle and advanced stages still cannot be completely cured. It is now evident that cell adhesion-mediated resistance (CAM-DR) limits the success of cancer therapies and is a great obstacle to overcome in the clinic. The interactions between tumor cells and extracellular matrix (ECM) molecules or adjacent cells may play a significant role in initiating the intracellular signaling pathways that are associated with cell proliferation, survival upon binding to their ligands. Recent studies illustrate that these adhesion-related factors may contribute to the survival of cancer cells after chemotherapeutic therapy, advantageous to resistant cells to proliferate and develop multiple mechanisms of drug resistance. In this review, we focus on the molecular basis of these interactions and the main signal transduction pathways that are involved in the enhancement of the cancer cells’ survival. Furthermore, therapies targeting interactions between cancer cells and their environment to enhance drug response or prevent the emergence of drug resistance will also be discussed.

ITGA8 positive cells in the conventional outflow tissue exhibit Schlemm's canal endothelial cell properties

AIMS

Elevated intraocular pressure is primarily induced by the increased resistance of conventional outflow of aqueous humor. Dysfunction of the juxtacanalicular region of trabecular meshwork (TM) and Schlemm's canal (SC) endothelium, as the main conventional outflow tissue, have been implicated as the major reasons for the increased resistance. Integrins are widespread in these tissues, especially alpha8 integrin (ITGA8). We aim to investigate the properties of cells expressing ITGA8 in the conventional outflow tissue.

MAIN METHODS

Fluorescence in situ hybridization (FISH) and immunofluorescence (IF) were performed to detect the mRNA and protein levels of ITGA8 in human conventional outflow tissue. ITGA8-positive cells were isolated from the cultured human TM cells through a magnetic bead-based approach. Flow Cytometry was used to determine the purification efficiency. The expressions of TM and SC biomarkers and dexamethasone-induced myocilin secretion capacity of ITGA8-positive cells was assessed by Real-time PCR, IF and Western blot. A gel contraction assay was performed to evaluate contractility of ITGA8-positive cells after endothelin 1 treatment.

KEY FINDINGS

ITGA8 was found with robust expression near the inner wall of SC endothelium. After purification, the proportion of ITGA8-positive cells were increased by about 10%. ITGA8-positive cells were identified with the properties as SC endothelial cells, such as more robust expressions of SC biomarkers, less dexamethasone-inducible myocilin expression, and stronger contractility.

SIGNIFICANCE

This study demonstrated that cells expressing ITGA8 in SC region possess more properties as SC endothelial cells. Our data implicate a crucial role of ITGA8 in aqueous humor (AH) outflow resistance regulation.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

The Extracellular Bone Marrow Microenvironment-A Proteomic Comparison of Constitutive Protein Release by In Vitro Cultured Osteoblasts and Mesenchymal Stem Cells

Simple Summary

Normal blood cells are formed in the bone marrow by a process called hematopoiesis. This process is supported by a network of non-hematopoietic cells including connective tissue cells, blood vessel cells and bone-forming cells. However, these cells can also support the growth of cancer cells, i.e., hematological malignancies (e.g., leukemias) and cancers that arise in another organ and spread to the bone marrow. Two of these cancer-supporting normal cells are bone-forming osteoblasts and a subset of connective tissue cells called mesenchymal stem cells. One mechanism for their cancer support is the release of proteins that support cancer cell proliferation and progression of the cancer disease. Our present study shows that both these normal cells release a wide range of proteins that support cancer cells, and inhibition of this protein-mediated cancer support may become a new strategy for cancer treatment.

Abstract

Mesenchymal stem cells (MSCs) and osteoblasts are bone marrow stromal cells that contribute to the formation of stem cell niches and support normal hematopoiesis, leukemogenesis and development of metastases from distant cancers. This support is mediated through cell–cell contact, release of soluble mediators and formation of extracellular matrix. By using a proteomic approach, we characterized the protein release by in vitro cultured human MSCs (10 donors) and osteoblasts (nine donors). We identified 1379 molecules released by these cells, including 340 proteins belonging to the GO-term Extracellular matrix. Both cell types released a wide range of functionally heterogeneous proteins including extracellular matrix molecules (especially collagens), several enzymes and especially proteases, cytokines and soluble adhesion molecules, but also several intracellular molecules including chaperones, cytoplasmic mediators, histones and non-histone nuclear molecules. The levels of most proteins did not differ between MSCs and osteoblasts, but 82 proteins were more abundant for MSC (especially extracellular matrix proteins and proteases) and 36 proteins more abundant for osteoblasts. Finally, a large number of exosomal proteins were identified. To conclude, MSCs and osteoblasts show extracellular release of a wide range of functionally diverse proteins, including several extracellular matrix molecules known to support cancer progression (e.g., metastases from distant tumors, increased relapse risk for hematological malignancies), and the large number of identified exosomal proteins suggests that exocytosis is an important mechanism of protein release.

Cadherins, Selectins, and Integrins in CAM-DR in Leukemia

The interaction between leukemia cells and the bone microenvironment is known to provide drug resistance in leukemia cells. This phenomenon, called cell adhesion-mediated drug resistance (CAM-DR), has been demonstrated in many subsets of leukemia including B- and T-acute lymphoblastic leukemia (B- and T-ALL) and acute myeloid leukemia (AML). Cell adhesion molecules (CAMs) are surface molecules that allow cell-cell or cell-extracellular matrix (ECM) adhesion. CAMs not only recognize ligands for binding but also initiate the intracellular signaling pathways that are associated with cell proliferation, survival, and drug resistance upon binding to their ligands. Cadherins, selectins, and integrins are well-known cell adhesion molecules that allow binding to neighboring cells, ECM proteins, and soluble factors. The expression of cadherin, selectin, and integrin correlates with the increased drug resistance of leukemia cells. This paper will review the role of cadherins, selectins, and integrins in CAM-DR and the results of clinical trials targeting these molecules.

The extracellular matrix: A key player in the pathogenesis of hematologic malignancies

Hematopoietic stem and progenitor cells located in the bone marrow lay the foundation for multiple lineages of mature hematologic cells. Bone marrow niches are architecturally complex with specific cellular, physiochemical, and biomechanical factors. Increasing evidence suggests that the bone marrow microenvironment contributes to the pathogenesis of hematological neoplasms. Numerous studies have deciphered the role of genetic mutations and chromosomal translocations in the development hematologic malignancies. Significant progress has also been made in understanding how the cellular components and cytokine interactions within the bone marrow microenvironment promote the evolution of hematologic cancers. Although the extracellular matrix is known to be a key player in the pathogenesis of various diseases, it's role in the progression of hematologic malignancies is less understood. In this review, we discuss the interactions between the extracellular matrix and malignant cells, and provide an overview of the role of extracellular matrix remodeling in sustaining hematologic malignancies.

Addressing the tumour microenvironment in early drug discovery: a strategy to overcome drug resistance and identify novel targets for cancer therapy

The tumour microenvironment (TME) comprises not only malignant and non-malignant cells, but also the extracellular matrix (ECM), secreted factors, and regulators of cellular functions. In addition to genetic alterations, changes of the biochemical/biophysical properties or cellular composition of the TME have been implicated in drug resistance. Here, we review the composition of the ECM and different elements of the TME contributing to drug resistance, including soluble factors, hypoxia, extracellular acidity, and cell adhesion properties. We discuss selected approaches for modelling the TME, current progress, and their use in low-and high-throughput assays for preclinical studies. Lastly, we summarise the status quo of advanced 3D cancer models compatible with high-throughput screening (HTS), the technical practicalities and challenges.

Rac1 repression reverses chemoresistance by targeting tumor metabolism

Tumor metabolism is exemplified by the increased rate of glucose utilization, a biochemical signature of cancer cells. The enhanced glucose hydrolysis enabled by the augmentation of glycolytic flux and the pentose phosphate pathway (PPP) plays a pivotal role in the growth and survival of neoplastic cells. In a recent report, it has been shown that in human breast cancer the GTP binding protein, Rac1 enables resistance to therapy, particularly against the DNA-damaging therapeutics. Significantly, the findings demonstrate that Rac1-dependent chemoresistance involves the upregulation of glycolytic flux as well as PPP. Using multiple approaches, the study demonstrates that disruption of Rac1 activity sensitizes cancer cells to DNA-damaging agents. More importantly, the data uncover a previously unknown PPP regulatory role of Rac1 in breast cancer. Finally, the authors also show the effectiveness and the feasibility of in vivo targeting of Rac1 to enhance the chemosensitivity of breast cancer. This elegant report provokes scientific curiosity to expand our understanding of the intricacies of the role and regulation of Rac1 in cancer.

Reciprocal Interplay Between Fibrillar Collagens and Collagen-Binding Integrins: Implications in Cancer Progression and Metastasis

Cancers are complex ecosystems composed of malignant cells embedded in an intricate microenvironment made of different non-transformed cell types and extracellular matrix (ECM) components. The tumor microenvironment is governed by constantly evolving cell-cell and cell-ECM interactions, which are now recognized as key actors in the genesis, progression and treatment of cancer lesions. The ECM is composed of a multitude of fibrous proteins, matricellular-associated proteins, and proteoglycans. This complex structure plays critical roles in cancer progression: it functions as the scaffold for tissues organization and provides biochemical and biomechanical signals that regulate key cancer hallmarks including cell growth, survival, migration, differentiation, angiogenesis, and immune response. Cells sense the biochemical and mechanical properties of the ECM through specialized transmembrane receptors that include integrins, discoidin domain receptors, and syndecans. Advanced stages of several carcinomas are characterized by a desmoplastic reaction characterized by an extensive deposition of fibrillar collagens in the microenvironment. This compact network of fibrillar collagens promotes cancer progression and metastasis, and is associated with low survival rates for cancer patients. In this review, we highlight how fibrillar collagens and their corresponding integrin receptors are modulated during cancer progression. We describe how the deposition and alignment of collagen fibers influence the tumor microenvironment and how fibrillar collagen-binding integrins expressed by cancer and stromal cells critically contribute in cancer hallmarks.

"Caught in the net": the extracellular matrix of the bone marrow in normal hematopoiesis and leukemia

The influence of the bone marrow microenvironment on normal hematopoiesis, but also leukemia, has largely been accepted. However, the focus has been predominantly on the role of various cell types or cytokines maintaining hematopoietic stem cells or protecting leukemia stem cells from different therapies. A frequently overlooked component of the bone marrow microenvironment is the extracellular matrix, which not only provides a mechanical scaffold, but also serves as a source of growth factors. We discuss here how extracellular matrix proteins directly or indirectly modulate hematopoietic stem cell physiology and influence leukemia progression. It is hoped that existing and future studies on this topic may propel forward the possibility of augmenting normal hematopoiesis and improving therapies for leukemia, for instance, by targeting of the extracellular matrix in the bone marrow.