BBA - Molecular Cell Research (v.1863, #3)

Intratumoral hypoxia is a common finding in breast cancer and is associated with a significantly increased risk of metastasis and patient mortality. Hypoxia-inducible factors activate the transcription of a large battery of genes encoding proteins that promote primary tumor vascularization and growth, stromal cell recruitment, extracellular matrix remodeling, premetastatic niche formation, cell motility, local tissue invasion, extravasation at sites of metastasis, and maintenance of the cancer stem cell phenotype that is required to generate secondary tumors. Recent preclinical studies suggest that the combination of cytotoxic chemotherapy with drugs that inhibit hypoxia-inducible factors may improve outcome for women with triple-negative breast cancer. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Bone metastasis; Lung metastasis; Lymph node metastasis; Mesenchymal stem cells; Microvesicles; Myeloid-derived suppressor cells; Tumor-associated macrophages;

Platelets are increasingly being recognized for promoting tumor growth and metastasis. Many cells derived from solid tumors have the ability to aggregate platelets, and this ability correlates with their metastatic potential. Over the past half century, our understanding of tumor cell-induced platelet aggregation (TCIPA) has grown beyond the simple concept that tumor cell-containing microthrombi mechanically embolize the microvasculature. Tumor cell-activated platelets secrete a multitude of factors that reciprocally act on tumor cells, as well as other cells within the tumor microenvironment; thus, affecting both parenychma and tumor-associated stroma. In this review, we summarize the current knowledge of tumor cell–platelet interactions and their influence on the tumor microenvironment, including how these interactions impact neoplastic epithelial cells, endothelial cells, pericytes, fibroblasts, immune cells, and early metastatic niches. In addition, we review the current knowledge of platelet–cancer cell interactions within hematological malignancies and speculate on how platelets may influence the leukemic microenvironment. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Platelets; Platelet secretion; Solid tumors; Microenvironment; Leukemia;

Chronic Lymphocytic Leukemia (CLL) is a malignancy of mature B lymphocytes which are highly dependent on interactions with the tissue microenvironment for their survival and proliferation. Critical components of the microenvironment are monocyte-derived nurselike cells (NLCs), mesenchymal stromal cells, T cells and NK cells, which communicate with CLL cells through a complex network of adhesion molecules, chemokine receptors, tumor necrosis factor (TNF) family members, and soluble factors. (Auto-) antigens and/or autonomous mechanisms activate the B-cell receptor (BCR) and its downstream signaling cascade in secondary lymphatic tissues, playing a central pathogenetic role in CLL. Novel small molecule inhibitors, including the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib and the phosphoinositide-3-kinase delta (PI3Kδ) inhibitor idelalisib, target BCR signaling and have become the most successful new therapeutics in this disease. We here review the cellular and molecular characteristics of CLL cells, and discuss the cellular components and key pathways involved in the cross-talk with their microenvironment. We also highlight the relevant novel treatment strategies, focusing on immunomodulatory agents and BCR signaling inhibitors and how these treatments disrupt CLL–microenvironment interactions. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: CLL; Nurselike cells; Stromal cells; BCR; BCR signaling; BCR signaling inhibitors;

The role of microenvironment and immunity in drug response in leukemia by Emyr Bakker; Malak Qattan; Luciano Mutti; Constantinos Demonacos; Marija Krstic-Demonacos (414-426).
Leukemia is a cancer of the white blood cells, with over 54,000 new cases per year diagnosed worldwide and a 5-year survival rate below 60%. This highlights a need for research into the mechanisms behind its etiology and causes of therapy failure. The bone marrow microenvironment, in which adult stem cells are maintained in healthy individuals, has been implicated as a source of chemoresistance and disease relapse. Here the various ways that the microenvironment can contribute to the resistance and persistence of leukemia are discussed. The targeting of the microenvironment by leukemia cells to create an environment more suitable for cancer progression is described. The role of soluble factors, drug transporters, microvesicles, as well as the importance of direct cell–cell contact, in addition to the effects of inflammation and immune surveillance in microenvironment-mediated drug resistance are discussed. An overview of the clinical potential of translating research findings to patients is also provided. Understanding of and further research into the role of the bone marrow microenvironment in leukemia progression and relapse are crucial towards developing more effective treatments and reduction in patient morbidity. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Leukemia; Microenvironment; Cancer; Inflammation; Immune surveillance; Novel therapeutics;

Galectin 3 is a member of a family of β-galactoside binding proteins and has emerged as an important regulator of diverse functions critical in cancer biology including apoptosis, metastasis, immune surveillance, molecular trafficking, mRNA splicing, gene expression, and inflammation. Galectin 3's ability to support cancer cell survival by intra-cellular and extra-cellular mechanisms suggests this molecule is an important component of the tumor microenvironment that potentially could be targeted for therapy. Data is emerging that Galectin 3 is elevated in many cancers including solid tumors and the cancers of the blood. Galectin 3 also appears to be a key molecule produced by tumor microenvironment support cells including mesenchymal stromal cells (MSC) to suppress immune surveillance by killing T cells and interfering with NK cell function and by supporting metastasis. Levels of Galectin 3 increase in the MSC of aging mice and perhaps this contributes to the development of cancer in the elderly. Galectin 3 modulates surface protein expression of a diverse set of glycoproteins including CD44 by regulating endocytosis of these proteins. In addition, Galectin 3 binding to receptor kinases such as CD45 and the T cell receptor is critical in the regulation of their function. In this review I will examine the various mechanisms how Galectin 3 supports chemoresistance and metastasis in solid tumors and in leukemia and lymphoma. I will also discuss possible therapeutic strategies to target this Galectin for cancer therapy. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Galectin 3 (LGALS3); Immune surveillance; Signal transduction; Apoptosis;

Roles of NGAL and MMP-9 in the tumor microenvironment and sensitivity to targeted therapy by Saverio Candido; Stephen L. Abrams; Linda S. Steelman; Kvin Lertpiriyapong; Timothy L. Fitzgerald; Alberto M. Martelli; Lucio Cocco; Giuseppe Montalto; Melchiorre Cervello; Jerry Polesel; Massimo Libra; James A. McCubrey (438-448).
Various, diverse molecules contribute to the tumor microenvironment and influence invasion and metastasis. In this review, the roles of neutrophil gelatinase-associated lipocalin (NGAL) and matrix metalloproteinase-9 (MMP-9) in the tumor microenvironment and sensitivity to therapy will be discussed. The lipocalin family of proteins has many important functions. For example when NGAL forms a complex with MMP-9 it increases its stability which is important in cancer metastasis. Small hydrophobic molecules are bound by NGAL which can alter their entry into and efflux from cells. Iron transport and storage are also influenced by NGAL activity. Regulation of iron levels is important for survival in the tumor microenvironment as well as metastasis. Innate immunity is also regulated by NGAL as it can have bacteriostatic properties. NGAL and MMP-9 expression may also affect the sensitivity of cancer cells to chemotherapy as well as targeted therapy. Thus NGAL and MMP-9 play important roles in key processes involved in metastasis as well as response to therapy. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: NGAL; MMP-9; Lcn2; Lipocalins; Siderocalins; Iron transport; Drug resistance;

Advances in understanding the acute lymphoblastic leukemia bone marrow microenvironment: From biology to therapeutic targeting by Francesca Chiarini; Annalisa Lonetti; Camilla Evangelisti; Francesca Buontempo; Ester Orsini; Cecilia Evangelisti; Alessandra Cappellini; Luca M. Neri; James A. McCubrey; Alberto M. Martelli (449-463).
The bone marrow (BM) microenvironment regulates the properties of healthy hematopoietic stem cells (HSCs) localized in specific niches. Two distinct microenvironmental niches have been identified in the BM, the “osteoblastic (endosteal)” and “vascular” niches. Nevertheless, these niches provide sanctuaries where subsets of leukemic cells escape chemotherapy-induced death and acquire a drug-resistant phenotype. Moreover, it is emerging that leukemia cells are able to remodel the BM niches into malignant niches which better support neoplastic cell survival and proliferation. This review focuses on the cellular and molecular biology of microenvironment/leukemia interactions in acute lymphoblastic leukemia (ALL) of both B- and T-cell lineage. We shall also highlight the emerging role of exosomes/microvesicles as efficient messengers for cell-to-cell communication in leukemia settings. Studies on the interactions between the BM microenvironment and ALL cells have led to the discovery of potential therapeutic targets which include cytokines/chemokines and their receptors, adhesion molecules, signal transduction pathways, and hypoxia-related proteins. The complex interplays between leukemic cells and BM microenvironment components provide a rationale for innovative, molecularly targeted therapies, designed to improve ALL patient outcome. A better understanding of the contribution of the BM microenvironment to the process of leukemogenesis and leukemia persistence after initial remission, may provide new targets that will allow destruction of leukemia cells without adversely affecting healthy HSCs. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis,Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Leukemia initiating cells; Chemoresistance; Relapse; Signaling pathways; Hypoxia; Exosomes/microvesicles;

Exosome-mediated microenvironment dysregulation in leukemia by Bijender Kumar; Mayra Garcia; Jodi L. Murakami; Ching-Cheng Chen (464-470).
The hematopoietic stem cell (HSC) niche is composed of a complex set of stromal support cells that maintain HSCs and promote normal hematopoiesis. We now know that molecular changes within the hematopoietic niche contribute to leukemia development. Leukemia cells often reorganize the hematopoietic niche to promote and support their own survival and growth. Here we will summarize recent works that decipher the normal hematopoietic niche cellular components and describe how the leukemia-transformed niche contributes to hematological malignances. Finally, we will discuss recent publications that highlight a possible role for exosomes in the leukemia-induced niche reorganization. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Exosomes; Niche; Leukemia cell; Hematopoietic stem cells;

Tumor microenvironment (TME)-driven immune suppression in B cell malignancy by Nicole S. Nicholas; Benedetta Apollonio; Alan G. Ramsay (471-482).
Immune checkpoint blockade antibodies and immunomodulatory drugs can unleash anti-tumor T cell immunity and mediate durable cancer regressions. However, only a fraction of patients currently respond to immunotherapy. Lymphoid malignancies are known to have clinically exploitable immune sensitivity and their intrinsic lymphoid tumor-microenvironment (TME) should make them natural targets for immunotherapy. However, accumulating evidence is showing that malignant cells engage in novel associations/interdependencies with reprogrammed immune and stromal cells in the TME that provide crucial contributions to the licencing of tumour progression and immune evasion (suppression of antitumor immune responses). In this review, we outline TME-driven contributions to the licencing of immune evasion mechanisms including the expression and activity of the immune checkpoint network, focussing on two types of B cell malignancy: indolent chronic lymphocytic leukemia (CLL) and aggressive diffuse large B-cell lymphoma (DLBCL). We also highlight recent therapeutic strategies to re-educate the TME to have anti-tumorigenic effects. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: CLL; DLBCL; PD-1; PD-L1; CTLA-4; Lenalidomide; Immune checkpoint blockade; T cells; Immune evasion;

Tumor microenvironment in diffuse large B-cell lymphoma: Matrixmetalloproteinases activation is mediated by osteopontin overexpression by Grazia Malaponte; Sameh Hafsi; Jerry Polesel; Giancarlo Castellano; Paola Spessotto; Claudio Guarneri; Silvana Canevari; Santo S. Signorelli; James A. McCubrey; Massimo Libra (483-489).
Non-Hodgkin lymphomas (NHL) are a heterogeneous group of lymphoproliferative malignancies with variable patterns of behavior and responses to therapy. NHL development and invasion depend on multiple interactions between tumor cells and non-neoplastic cells. Such interactions are usually modulated by several cytokines. Accordingly, it was demonstrated that matrix-metalloproteinase (MMP)-2 and MMP-9 were activated in human lymphoid cell lines by interleukin-6 (IL-6). The activation of these enzymes is associated with tumor invasion and metastasis in human cancers. MMPs are also activated in several cancers by osteopontin (OPN), a secreted glycoprotein that regulates cell adhesion, migration, and survival. However, it is still unclear if MMPs play a role in NHL development and if their activation is determined by OPN and/or IL-6. In the present study, two groups of 78 NHL patients and 95 healthy donors were recruited for the analysis of OPN, MMP-2, MMP-9 and IL-6.Significant higher circulating levels of MMP-2, MMP-9, OPN and IL-6 were observed in NHL patients when compared to healthy donors. Similar data were obtained by analyzing the activity of both MMP-2 and MMP-9. The multivariate regression model indicates that, in both NHL cases and healthy donors, OPN is associated with the increase of MMP-2 and MMP-9 levels independently of IL-6. These data were first confirmed by “in silico” analyses and then by “in vitro” experiments conducted on peripheral blood mononuclear cells randomly selected from both NHL patients and healthy donors.Overall, our data suggest that the activation of MMPs in NHL development is mostly associated with OPN. However, IL-6 may play an important role in the lymphomagenesis through the activation of other molecular pathways. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: B-cell lymphomas; Osteopontin; Matrixmetalloproteinase; Interleukin-6;

Normal hematopoiesis and lack of β-catenin activation in osteoblasts of patients and mice harboring Lrp5 gain-of-function mutations by Marta Galán-Díez; Adiba Isa; Marco Ponzetti; Morten Frost Nielsen; Moustapha Kassem; Stavroula Kousteni (490-498).
Osteoblasts are emerging regulators of myeloid malignancies since genetic alterations in them, such as constitutive activation of β-catenin, instigate their appearance. The LDL receptor-related protein 5 (LRP5), initially proposed to be a co-receptor for Wnt proteins, in fact favors bone formation by suppressing gut-serotonin synthesis. This function of Lrp5 occurring in the gut is independent of β-catenin activation in osteoblasts. However, it is unknown whether Lrp5 can act directly in osteoblast to influence other functions that require β-catenin signaling, particularly, the deregulation of hematopoiesis and leukemogenic properties of β-catenin activation in osteoblasts, that lead to development of acute myeloid leukemia (AML). Using mice with gain-of-function (GOF) Lrp5 alleles (Lrp5 A214V ) that recapitulate the human high bone mass (HBM) phenotype, as well as patients with the T253I HBM Lrp5 mutation, we show here that Lrp5 GOF mutations in both humans and mice do not activate β-catenin signaling in osteoblasts. Consistent with a lack of β-catenin activation in their osteoblasts, Lrp5 A214V mice have normal trilinear hematopoiesis. In contrast to leukemic mice with constitutive activation of β-catenin in osteoblasts (Ctnnb1 CAosb ), accumulation of early myeloid progenitors, a characteristic of AML, myeloid-blasts in blood, and segmented neutrophils or dysplastic megakaryocytes in the bone marrow, are not observed in Lrp5 A214V mice. Likewise, peripheral blood count analysis in HBM patients showed normal hematopoiesis, normal percentage of myeloid cells, and lack of anemia. We conclude that Lrp5 GOF mutations do not activate β-catenin signaling in osteoblasts. As a result, myeloid lineage differentiation is normal in HBM patients and mice. This article is part of a Special Issue entitled: Tumor Microenvironment Regulation of Cancer Cell Survival, Metastasis, Inflammation, and Immune Surveillance edited by Peter Ruvolo and Gregg L. Semenza.
Keywords: Lrp5; β-catenin; Osteoblasts; High bone mass (HBM); Hematopoiesis; Leukemia;