Microenvironment, tumor cell plasticity, and cancer. Curr Opin Oncol. 2015;27:64-70. [PMID: 25415136 DOI: 10.1097/cco.0000000000000154]

Apical expansion of calvarial osteoblasts and suture patency is dependent on fibronectin cues

The skull roof, or calvaria, is comprised of interlocking plates of bones that encase the brain. Separating these bones are fibrous sutures that permit growth. Currently, we do not understand the instructions for directional growth of the calvaria, a process which is error-prone and can lead to skeletal deficiencies or premature suture fusion (craniosynostosis, CS). Here, we identify graded expression of fibronectin (FN1) in the mouse embryonic cranial mesenchyme (CM) that precedes the apical expansion of calvaria. Conditional deletion of Fn1 or Wasl leads to diminished frontal bone expansion by altering cell shape and focal actin enrichment, respectively, suggesting defective migration of calvarial progenitors. Interestingly, Fn1 mutants have premature fusion of coronal sutures. Consistently, syndromic forms of CS in humans exhibit dysregulated FN1 expression, and we also find FN1 expression altered in a mouse CS model of Apert syndrome. These data support a model of FN1 as a directional substrate for calvarial osteoblast migration that may be a common mechanism underlying many cranial disorders of disparate genetic etiologies.

Cancer cell response to extrinsic and intrinsic mechanical cue: opportunities for tumor apoptosis strategies

Increasing studies have revealed the importance of mechanical cues in tumor progression, invasiveness and drug resistance. During malignant transformation, changes manifest in either the mechanical properties of the tissue or the cellular ability to sense and respond to mechanical signals. The major focus of the review is the subtle correlation between mechanical cues and apoptosis in tumor cells from a mechanobiology perspective. To begin, we focus on the intracellular force, examining the mechanical properties of the cell interior, and outlining the role that the cytoskeleton and intracellular organelle-mediated intracellular forces play in tumor cell apoptosis. This article also elucidates the mechanisms by which extracellular forces guide tumor cell mechanosensing, ultimately triggering the activation of the mechanotransduction pathway and impacting tumor cell apoptosis. Finally, a comprehensive examination of the present status of the design and development of anti-cancer materials targeting mechanotransduction is presented, emphasizing the underlying design principles. Furthermore, the article underscores the need to address several unresolved inquiries to enhance our comprehension of cancer therapeutics that target mechanotransduction.

Phenotypic Characterization of 2D and 3D Prostate Cancer Cell Systems Using Electrical Impedance Spectroscopy

Prostate cancer is the second leading cause of death in men. A challenge in treating prostate cancer is overcoming cell plasticity, which links cell phenotype changes and chemoresistance. In this work, a microfluidic device coupled with electrical impedance spectroscopy (EIS), an electrode-based cell characterization technique, was used to study the electrical characteristics of phenotype changes for (1) prostate cancer cell lines (PC3, DU145, and LNCaP cells), (2) cells grown in 2D monolayer and 3D suspension cell culture conditions, and (3) cells in the presence (or absence) of the anti-cancer drug nigericin. To validate observations of phenotypic change, we measured the gene expression of two epithelial markers, E-cadherin (CDH1) and Tight Junction Protein 1 (ZO-1). Our results showed that PC3, DU145, and LNCaP cells were discernible with EIS. Secondly, moderate phenotype changes based on differences in cell culture conditions were detected with EIS and supported by the gene expression of CDH1. Lastly, we showed that EIS can detect chemoresistant-related cell phenotypes with nigericin drug treatment. EIS is a promising label-free tool for detecting cell phenotype changes associated with chemoresistance. Further development will enable the detection and characterization of many other types of cancer cells.

Biophysical control of plasticity and patterning in regeneration and cancer

Cells and tissues display a remarkable range of plasticity and tissue-patterning activities that are emergent of complex signaling dynamics within their microenvironments. These properties, which when operating normally guide embryogenesis and regeneration, become highly disordered in diseases such as cancer. While morphogens and other molecular factors help determine the shapes of tissues and their patterned cellular organization, the parallel contributions of biophysical control mechanisms must be considered to accurately predict and model important processes such as growth, maturation, injury, repair, and senescence. We now know that mechanical, optical, electric, and electromagnetic signals are integral to cellular plasticity and tissue patterning. Because biophysical modalities underly interactions between cells and their extracellular matrices, including cell cycle, metabolism, migration, and differentiation, their applications as tuning dials for regenerative and anti-cancer therapies are being rapidly exploited. Despite this, the importance of cellular communication through biophysical signaling remains disproportionately underrepresented in the literature. Here, we provide a review of biophysical signaling modalities and known mechanisms that initiate, modulate, or inhibit plasticity and tissue patterning in models of regeneration and cancer. We also discuss current approaches in biomedical engineering that harness biophysical control mechanisms to model, characterize, diagnose, and treat disease states.

A microfluidic mechano-chemostat for tissues and organisms reveals that confined growth is accompanied with increased macromolecular crowding

Conventional culture conditions are oftentimes insufficient to study tissues, organisms, or 3D multicellular assemblies. They lack both dynamic chemical and mechanical control over the microenvironment. While specific microfluidic devices have been developed to address chemical control, they often do not allow the control of compressive forces emerging when cells proliferate in a confined environment. Here, we present a generic microfluidic device to control both chemical and mechanical compressive forces. This device relies on the use of sliding elements consisting of microfabricated rods that can be inserted inside a microfluidic device. Sliding elements enable the creation of reconfigurable closed culture chambers for the study of whole organisms or model micro-tissues. By confining the micro-tissues, we studied the biophysical impact of growth-induced pressure and showed that this mechanical stress is associated with an increase in macromolecular crowding, shedding light on this understudied type of mechanical stress. Our mechano-chemostat allows the long-term culture of biological samples and can be used to study both the impact of specific conditions as well as the consequences of mechanical compression.

Biophysical determinants of cancer organotropism

Metastasis remains the leading cause of cancer lethality. The 'seed/soil' hypothesis provides the framework to explain this cancer phenomenon where the concept of organotropism has been in part mechanistically explained by the properties of the tumor cells and their compatibility with the stromal environment of the distal site. The 'mechanical' hypothesis counters that non-random seeding is driven solely by the circulation patterns and vascular networks of organ systems. We incorporate concepts of mechanobiology and revisit the two hypotheses to provide additional insights into the mechanisms that regulate organ selection during metastatic outgrowth. We focus on the latter stages of the metastatic cascade and examine the role of the endothelium in regulating organ selectivity.

Apical expansion of calvarial osteoblasts and suture patency is dependent on graded fibronectin cues

The skull roof, or calvaria, is comprised of interlocking plates of bone. Premature suture fusion (craniosynostosis, CS) or persistent fontanelles are common defects in calvarial development. Although some of the genetic causes of these disorders are known, we lack an understanding of the instructions directing the growth and migration of progenitors of these bones, which may affect the suture patency. Here, we identify graded expression of Fibronectin (FN1) protein in the mouse embryonic cranial mesenchyme (CM) that precedes the apical expansion of calvarial osteoblasts. Syndromic forms of CS exhibit dysregulated FN1 expression, and we find FN1 expression is altered in a mouse CS model as well. Conditional deletion of Fn1 in CM causes diminished frontal bone expansion by altering cell polarity and shape. To address how osteoprogenitors interact with the observed FN1 prepattern, we conditionally ablate Wasl/N-Wasp to disrupt F-actin junctions in migrating cells, impacting lamellipodia and cell-matrix interaction. Neural crest-targeted deletion of Wasl results in a diminished actin network and reduced expansion of frontal bone primordia similar to conditional Fn1 mutants. Interestingly, defective calvaria formation in both the Fn1 and Wasl mutants occurs without a significant change in proliferation, survival, or osteogenesis. Finally, we find that CM-restricted Fn1 deletion leads to premature fusion of coronal sutures. These data support a model of FN1 as a directional substrate for calvarial osteoblast migration that may be a common mechanism underlying many cranial disorders of disparate genetic etiologies.

EMT and Inflammation: Crossroads in HCC

Hepatocellular carcinoma is one of the major causes of cancer-related deaths worldwide and is associated with several inflammatory mediators, since 90% of HCCs occur based on chronic hepatitis B or C, alcoholism or increasingly metabolic syndrome-associated inflammation. EMT is a physiological process, with coordinated changes in epithelial gene signatures and is regulated by multiple factors, including cytokines and growth factors such as TGFβ, EGF, and FGF. Recent reports propose a strong association between EMT and inflammation, which is also correlated with tumor aggressiveness and poor outcomes. Cellular heterogeneity results collectively as an outcome of EMT, inflammation, and the tumor microenvironment, and it plays a fundamental role in the progression, complexity of cancer, and chemoresistance. In this review, we highlight recent developments concerning the association of EMT and inflammation in the context of HCC progression. Identifying potential EMT-related biomarkers and understanding EMT regulatory molecules will likely contribute to promising developments in clinical practice and will be a valuable tool for predicting metastasis in general and specifically in HCC.

[3D Tumor organoid models produced by cellular capsules technology CCT]

Monolayer cultures of cell lines and derived-patient cells have long been the in vitro model of choice in oncology. In particular, these models have made it possible to decipher the mechanisms that determine tumor proliferation and invasion. However these 2D models are insufficient because they do not take into account the spatial organization of cells and their interactions with each other or with the extracellular matrix. In the context of cancer, there is a need to develop new 3D (tumoroid) models in order to gain a better understanding of the development of these pathologies but also to assess the penetration of drugs through a tissue and the associated cellular response. We present here the cell capsule technology (CCT), which allows the production of different tumoroid models: simple or more complex 3D culture models including co-culture of tumor cells with components of the microenvironment (fibroblasts, matrix, etc.). The development of these new 3D culture systems now makes it possible to propose refined physiopathological models that will allow the implementation of improved targeted therapeutic strategies.

Role of the bone marrow microenvironment in drug resistance of hematological malignances

The unique features of the tumor microenvironment (TME) govern the biological properties of many cancers, including hematological malignancies. TME factors can trigger invasion, and protect against drug cytotoxicity by inhibiting apoptosis and activating specific signaling pathways (e.g. NF-ΚB). TME remodeling is facilitated due to the high self-renewal ability of the bone marrow. Progressing tumor cells can alter some extracellular matrix (ECM) components which act as a barrier to drug penetration in the TME. The initial progression of the cell cycle is controlled by the MAPK pathway (Raf/MEK/ERK) and Hippo pathway, while the final phase is regulated by the PI3K/Akt /mTOR and WNT pathways. In this review we summarize the main signaling pathways involved in drug resistance (DR) and some mechanisms by which DR can occur in the bone marrow. The relationship between autophagy, endoplasmic reticulum stress, and cellular signaling pathways in DR and apoptosis are covered in relation to the TME.

Yu-Ping-Feng Formula Exerts Antilung Cancer Effects by Remodeling the Tumor Microenvironment through Regulating Myeloid-Derived Suppressor Cells

Yu-Ping-Feng (YPF) formula is a classical prescription used for enhancing the body's immunity function in traditional Chinese medicine (TCM). In clinical practice, the YPF formula has been reported to exhibit antilung cancer and immunomodulatory effect. However, the relationship between them remains unclear. The present study aimed to investigate the antilung cancer effect of the YPF formula and its immune-related mechanisms. The C57BL/6 tumor-bearing mice model was established and randomly divided into the YPF group and the control group. Tumor volume, spleen weight, and survival in both groups were measured and evaluated during 28 days of consecutive intervention. Flow cytometry was used to detect the proportion of immune cell subsets. Myeloid-derived suppressor cells (MDSCs) were induced in vitro from bone marrow cells. After intervention by the YPF formula, CCK-8 and flow cytometry analyses were performed to detect proliferation and apoptosis of MDSCs. A coculture system containing T cells and MDSCs was established to further study the role of MDSCs in the regulation of T-cell subsets proportion by the YPF formula. The expressions of MDSCs-related genes and proteins were detected by RT-PCR and Western blotting. The results showed the YPF formula inhibited tumor growth, reduced spleen weight, and prolonged the survival of mice. Besides, the proportions of MDSCs subsets and Regulatory T (Treg) in the YPF group decreased, whereas those of CD₄⁺T and CD₈⁺T increased both in vitro and in vivo. CCK-8 and flow cytometry demonstrated that the YPF formula could inhibit proliferation and promote apoptosis of MDSCs. The coculture experiments further confirmed that MDSCs served a critical role in regulating the tumor microenvironment by the YPF formula. RT-PCR and Western blotting indicated that the levels of MDSCs' activation and proliferation-related proteins and genes were downregulated in the YPF group. Therefore, our results demonstrated that the YPF formula could promote apoptosis and inhibit the proliferation of MDSCs. As a result, the negative regulatory effect on the positive immune cells induced by MDSCs was weakened, thus achieving the antilung cancer effect by remodeling the tumor microenvironment.

B Cells versus T Cells in the Tumor Microenvironment of Malignant Lymphomas. Are the Lymphocytes Playing the Roles of Muhammad Ali versus George Foreman in Zaire 1974?

Malignant lymphomas are a heterogeneous group of malignancies that develop both in nodal and extranodal sites. The different tissues involved and the highly variable clinicopathological characteristics are linked to the association between the lymphoid neoplastic cells and the tissues they infiltrate. The immune system has developed mechanisms to protect the normal tissue from malignant growth. In this review, we aim to explain how T lymphocyte-driven control is linked to tumor development and describe the tumor-suppressive components of the resistant framework. This manuscript brings forward a new insight with regard to intercellular and intracellular signaling, the immune microenvironment, the impact of therapy, and its predictive implications. A better understanding of the key components of the lymphoma environment is important to properly assess the role of both B and T lymphocytes, as well as their interplay, just as two legendary boxers face each other in a heavyweight title final, as was the case of Ali versus Foreman.

Cellular plasticity and drug resistance in sarcoma

Sarcomas, originating from mesenchymal progenitor stem cells, are a group of rare malignant tumors with poor prognosis. Wide surgical resection, chemotherapy, and radiotherapy are the most common sarcoma treatments. However, sarcomas' response rates to chemotherapy are quite low and sarcoma cells can have intrinsic or acquired resistance after treatment with chemotherapeutics drugs, leading to the development of multi-drug resistance (MDR). Cancer cellular plasticity plays pivotal roles in cancer initiation, progression, therapy resistance and cancer relapse. Moreover, cancer cellular plasticity can be regulated by a multitude of factors, such as genetic and epigenetic alterations, tumor microenvironment (TME) or selective pressure imposed by treatment. Recent studies have demonstrated that cellular plasticity is involved in sarcoma progression and chemoresistance. It's essential to understand the molecular mechanisms of cellular plasticity as well as its roles in sarcoma progression and drug resistance. Therefore, this review focuses on the regulatory mechanisms and pathological roles of these diverse cellular plasticity programs in sarcoma. Additionally, we propose cellular plasticity as novel therapeutic targets to reduce sarcoma drug resistance.

Electrical Impedance Spectroscopy for Monitoring Chemoresistance of Cancer Cells

Electrical impedance spectroscopy (EIS) is an electrokinetic method that allows for the characterization of intrinsic dielectric properties of cells. EIS has emerged in the last decade as a promising method for the characterization of cancerous cells, providing information on inductance, capacitance, and impedance of cells. The individual cell behavior can be quantified using its characteristic phase angle, amplitude, and frequency measurements obtained by fitting the input frequency-dependent cellular response to a resistor-capacitor circuit model. These electrical properties will provide important information about unique biomarkers related to the behavior of these cancerous cells, especially monitoring their chemoresistivity and sensitivity to chemotherapeutics. There are currently few methods to assess drug resistant cancer cells, and therefore it is difficult to identify and eliminate drug-resistant cancer cells found in static and metastatic tumors. Establishing techniques for the real-time monitoring of changes in cancer cell phenotypes is, therefore, important for understanding cancer cell dynamics and their plastic properties. EIS can be used to monitor these changes. In this review, we will cover the theory behind EIS, other impedance techniques, and how EIS can be used to monitor cell behavior and phenotype changes within cancerous cells.

Quantitative analysis for the differences in vasculogenic activity and sensitivity to angiogenic stimulants between human glioma cells and normal endothelial cells

Neovascularization is a histological feature of glioma, especially of glioblastoma (GBM), being associated with tumor invasiveness and poor prognosis. However, current anti-angiogenic therapies targeting vascular endothelial cells (ECs), has exhibited poor efficacy in some GBM cases. This may be at least partially attributed to the potential of glioblastoma cells to construct blood supply chain via vasculogenic mimicry or endothelial differentiation. This study aims to explore differences in vasculogenic activity and sensitivity to angiogenic stimulants between normal human ECs and glioma cells of different grades. We found that grade IV U87 GBM cells showed highly inducible vasculogenic activity either in the orthotopic xenograft model or under in vitro angiogenic stimulants as compared with grade II CHG5 glioma cells. The hypoxia mimetic more strongly induced in vitro vasculogenic capacity and endothelial marker expression of U87 GBM cells than the stimulation with multiple proangiogenic growth factors (vascular endothelial growth factor, basic fibroblast growth factor and epidermal growth factor). In contrast, proangiogenic effect of hypoxia on human umbilical vein endothelial cells (HUVECs) was weaker than on U87 GBM cells. In addition, it was also observed that the in vitro vasculogenic process of U87 cells started later but lasted longer than that of HUVECs. These results demonstrate that when compared with normal ECs, high-grade glioma cells basically possess weaker vasculogenic activity, but exhibit higher sensitivity and longer-lasting response to angiogenic stimulants, especially to hypoxia. This may be helpful to develop novel anti-angiogenic strategies targeting both vascular ECs and vasculogenic glioma cells.

Prognostic and predictive value of immune/stromal-related gene biomarkers in renal cell carcinoma

Immune/stromal-associated genes may be promising biomarkers for cancer diagnosis and the determination of clinical cancer treatment options. The aim of the present study was to identify prognostic stromal/immune-associated genes in renal cell carcinoma (RCC). RCC gene expression data (885 cases) were obtained from The Cancer Genome Atlas database. Immune/stromal scores were calculated by using the ESTIMATE package in R. Immune/stromal scores were significantly associated with Tumor-Node-Metastasis stage, clinical stage and overall survival rate (P<0.05). There were 419 differentially expressed genes (DEGs) based on immune scores and 738 DEGs based on stromal scores. Among these DEGs, 406 DEGs based on stromal scores and 252 DEGs based on immune scores were significantly associated with overall survival rate (P<0.05). The biological functions of these DEGs were primarily enriched in the 'immune response' and 'regulation of cell migration and proliferation'. These DEGs were observed in a protein-protein interaction network. A LASSO Cox regression model was used to build a prognostic 6 gene-based classifier, including the IL21R, ATP6V1C2, GBP1, P2RY10, GBP4 and TNNC2 genes [area under the curve (AUC) =0.776]. The predictive model which combined this classifier with clinical prognostic factors had a high accuracy in predicting patient survival in RCC (combined AUC =0.899). Taken together, these results demonstrated that there are significant associations between immune/stromal scores and clinicopathological staging. A set of tumor microenvironment-associated genes that have powerful prognostic value in patients with RCC were identified in the present study.

Changes in extracellular matrix in different stages of colorectal cancer and their effects on proliferation of cancer cells

BACKGROUND

The extracellular matrix is the main component of the tumor microenvironment. Extracellular matrix remodels with the oncogenesis and development of tumors. Previous studies usually focused on the changes of proteins in normal colorectal tissues and colorectal cancers. Little is known about the changes in the extracellular matrix in different stages of colorectal cancer and the effects of these changes on the development of this cancer.

AIM

To test the changes of type I collagen, type IV collagen, matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-3 (TIMP-3) in different stages of colorectal cancer and the effects of these changes on the proliferation of cancer cells.

METHODS

The extracellular matrix from various stages of colorectal cancer and normal colon tissue was obtained by using acellular technology. We used proteomics to detect the differential expression of proteins between normal colon tissues and colorectal cancer tissues, and then we used Western blot to observe their expression in each stage of colorectal cancer and in normal colon tissue. By co-culturing the extracellular matrix and HT29 colon cancer cells in vivo and in vitro, we tested the cancer cell proliferation rate in vitro by methyl thiazolyl tetrazolium (MTT) assay and in vivo by measuring the tumor volume.

RESULTS

The expression of type I collagen and MMP-2 increased with increased tumor stage. The expression of MMP-9 was higher in colorectal cancer tissues and was highest in stage III cancer. The expression of type IV collagen and TIMP-3 decreased with increased tumor stage. The proliferation rate of cancer cells in the extracellular matrix of colorectal cancer was higher than that in the extracellular matrix of the normal colon.

CONCLUSION

These data suggest that the extracellular matrix structure and composition become disorganized during the development of tumors, which is more conducive for the growth of cancer cells.

Integrins as biomechanical sensors of the microenvironment

Integrins, and integrin-mediated adhesions, have long been recognized to provide the main molecular link attaching cells to the extracellular matrix (ECM) and to serve as bidirectional hubs transmitting signals between cells and their environment. Recent evidence has shown that their combined biochemical and mechanical properties also allow integrins to sense, respond to and interact with ECM of differing properties with exquisite specificity. Here, we review this work first by providing an overview of how integrin function is regulated from both a biochemical and a mechanical perspective, affecting integrin cell-surface availability, binding properties, activation or clustering. Then, we address how this biomechanical regulation allows integrins to respond to different ECM physicochemical properties and signals, such as rigidity, composition and spatial distribution. Finally, we discuss the importance of this sensing for major cell functions by taking cell migration and cancer as examples.

The CTLH Complex in Cancer Cell Plasticity

Cancer cell plasticity is the ability of cancer cells to intermittently morph into different fittest phenotypic states. Due to the intrinsic capacity to change their composition and interactions, protein macromolecular complexes are the ideal instruments for transient transformation. This review focuses on a poorly studied mammalian macromolecular complex called the CTLH (carboxy-terminal to LisH) complex. Currently, this macrostructure includes 11 known members (ARMC8, GID4, GID8, MAEA, MKLN1, RMND5A, RMND5B, RANBP9, RANBP10, WDR26, and YPEL5) and it has been shown to have E3-ligase enzymatic activity. CTLH proteins have been linked to all fundamental biological processes including proliferation, survival, programmed cell death, cell adhesion, and migration. At molecular level, the complex seems to interact and intertwine with key signaling pathways such as the PI3-kinase, WNT, TGFβ, and NFκB, which are key to cancer cell plasticity. As a whole, the CTLH complex is overexpressed in the most prevalent types of cancer and may hold the key to unlock many of the biological secrets that allow cancer cells to thrive in harsh conditions and resist antineoplastic therapy.

Radiation and Stemness Phenotype May Influence Individual Breast Cancer Outcomes: The Crucial Role of MMPs and Microenvironment

Breast cancer is the most common cancer in women. Radiotherapy (RT) is one of the mainstay treatments for cancer but in some cases is not effective. Cancer stem cells (CSCs) within the tumor can be responsible for recurrence and metastasis after RT. Matrix metalloproteases (MMPs), regulated mainly by tissue inhibitors of metalloproteinases (TIMPs) and histone deacetylases (HDACs), may also contribute to tumor development by modifying its activity after RT. The aim of this work was to study the effects of RT on the expression of MMPs, TIMPs and HDACs on different cell subpopulations in MCF-7, MDA-MB-231 and SK-BR-3 cell lines. We assessed the in vitro expression of these genes in different 3D culture models and induced tumors in female NSG mice by orthotopic xenotransplants. Our results showed that gene expression is related to the cell subpopulation studied, the culture model used and the single radiation dose administered. Moreover, the crucial role played by the microenvironment in terms of cell interactions and CSC plasticity in tumor growth and RT outcome is also shown, supporting the use of higher doses (6 Gy) to achieve better control of tumor development.

Mechanisms of 3D cell migration

Cell migration is essential for physiological processes as diverse as development, immune defence and wound healing. It is also a hallmark of cancer malignancy. Thousands of publications have elucidated detailed molecular and biophysical mechanisms of cultured cells migrating on flat, 2D substrates of glass and plastic. However, much less is known about how cells successfully navigate the complex 3D environments of living tissues. In these more complex, native environments, cells use multiple modes of migration, including mesenchymal, amoeboid, lobopodial and collective, and these are governed by the local extracellular microenvironment, specific modalities of Rho GTPase signalling and non-muscle myosin contractility. Migration through 3D environments is challenging because it requires the cell to squeeze through complex or dense extracellular structures. Doing so requires specific cellular adaptations to mechanical features of the extracellular matrix (ECM) or its remodelling. In addition, besides navigating through diverse ECM environments and overcoming extracellular barriers, cells often interact with neighbouring cells and tissues through physical and signalling interactions. Accordingly, cells need to call on an impressively wide diversity of mechanisms to meet these challenges. This Review examines how cells use both classical and novel mechanisms of locomotion as they traverse challenging 3D matrices and cellular environments. It focuses on principles rather than details of migratory mechanisms and draws comparisons between 1D, 2D and 3D migration.

The plasma membrane as a mechanochemical transducer

Cells are constantly submitted to external mechanical stresses, which they must withstand and respond to. By forming a physical boundary between cells and their environment that is also a biochemical platform, the plasma membrane (PM) is a key interface mediating both cellular response to mechanical stimuli, and subsequent biochemical responses. Here, we review the role of the PM as a mechanosensing structure. We first analyse how the PM responds to mechanical stresses, and then discuss how this mechanical response triggers downstream biochemical responses. The molecular players involved in PM mechanochemical transduction include sensors of membrane unfolding, membrane tension, membrane curvature or membrane domain rearrangement. These sensors trigger signalling cascades fundamental both in healthy scenarios and in diseases such as cancer, which cells harness to maintain integrity, keep or restore homeostasis and adapt to their external environment. This article is part of a discussion meeting issue 'Forces in cancer: interdisciplinary approaches in tumour mechanobiology'.

Expression of Alpha-Enolase (ENO1), Myc Promoter-Binding Protein-1 (MBP-1) and Matrix Metalloproteinases (MMP-2 and MMP-9) Reflect the Nature and Aggressiveness of Breast Tumors

Breast cancer is a complex and heterogeneous disease: Several molecular alterations cause cell proliferation and the acquisition of an invasive phenotype. Extracellular matrix (ECM) is considered essential for sustaining tumor growth and matrix metalloproteinases (MMPs) have been identified as drivers of many aspects of the tumor phenotype. Mounting evidence indicates that both α-enolase (ENO1) and Myc promoter-binding protein-1 (MBP-1) also played pivotal roles in tumorigenesis, although as antagonists. ENO1 is involved in cell growth, hypoxia tolerance and autoimmune activities besides its major role in the glycolysis pathway. On the contrary, MBP-1, an alternative product of ENO1, suppresses cell proliferation and the invasive ability of cancer cells. Since an important task in personalized medicine is to discriminate a different subtype of patients with different clinical outcomes including chances of recurrence and metastasis, we investigated the functional relationship between ENO1/MBP-1 expression and MMP-2 and MMP-9 activity levels in both tissues and sera of breast cancer patients. We focused on the clinical relevance of ENO1 and MMPs (MMP-2 and MMP-9) overexpression in breast cancer tissues: The association between the higher ENO1, MMP-2 and MMP-9 expression with a worse prognosis suggest that the elevated ENO1 and MMPs expression are promising biomarkers for breast cancer. A relationship seems to exist between MBP-1 expression and the decrease in the activity levels of MMP-9 in cancer tissues and MMP-2 in sera. Moreover, the sera of breast cancer patients grouped for MBP-1 expression differentially induced, in vitro, cell proliferation and migration. Our findings support the hypothesis of patient’s stratification based on ENO1, MBP-1 and MMPs expression. Elucidating the molecular pathways through which MBP-1 influences MMPs expression and breast cancer regression can lead to the discovery of new management strategies.

HIF-1α is Overexpressed in Odontogenic Keratocyst Suggesting Activation of HIF-1α and NOTCH1 Signaling Pathways

Background: The odontogenic keratocyst (OKC) is an odontogenic cyst that shows aggressive and intriguing biological behavior. It is suggested that a hypoxic environment occurs in OKC, which led us to investigate the immunoexpression and location of hypoxia-inducible factor 1-alpha (HIF-1α) and other hypoxia-related proteins. Methods: Twenty cases of OKC were evaluated for the expression of Notch homolog 1 (NOTCH1), HIF-1α, disintegrin and metalloproteinase domain-containing protein 12 (ADAM-12), and heparin-binding epidermal growth factor-like growth factor (HBEGF) by immunohistochemistry and compared to eight control cases of calcifying odontogenic cystic (COC), orthokeratinized odontogenic cyst (OOC), and normal oral mucosa (OM) in basal and parabasal layers. Results: In OKC, all the proteins tested were expressed significantly higher in both basal (except for NOTCH1 and HBEGF in OOC) and suprabasal epithelial layers compared to controls. Looking at the epithelial layers within OKC, we observed an increased NOTCH1 and HIF-1α expression in parabasal layers. Conclusions: These results suggest that hypoxia occurs more intensively in OKC compared to COC, OM, and OOC. Hypoxia appeared to be stronger in parabasal layers as observed by higher HIF-1α expression in upper cells. Overexpression of NOTCH1, ADAM-12, and HBEGF in OKC was observed, which suggests that microenvironmental hypoxia could potentially regulate the expression of hypoxia-related proteins, and consequently, its clinical and biological behavior.

The Role of the Extracellular Matrix and Its Molecular and Cellular Regulators in Cancer Cell Plasticity

The microenvironment encompasses all components of a tumor other than the cancer cells themselves. It is highly heterogenous, comprising a cellular component that includes immune cells, fibroblasts, adipocytes, and endothelial cells, and a non-cellular component, which is a meshwork of polymeric proteins and accessory molecules, termed the extracellular matrix (ECM). The ECM provides both a biochemical and biomechanical context within which cancer cells exist. Cancer progression is dependent on the ability of cancer cells to traverse the ECM barrier, access the circulation and establish distal metastases. Communication between cancer cells and the microenvironment is therefore an important aspect of tumor progression. Significant progress has been made in identifying the molecular mechanisms that enable cancer cells to subvert the immune component of the microenvironment to facilitate tumor growth and spread. While much less is known about how the tumor cells adapt to changes in the ECM nor indeed how they influence ECM structure and composition, the importance of the ECM to cancer progression is now well established. Plasticity refers to the ability of cancer cells to modify their physiological characteristics, permitting them to survive hostile microenvironments and resist therapy. Examples include the acquisition of stemness characteristics and the epithelial-mesenchymal and mesenchymal-epithelial transitions. There is emerging evidence that the biochemical and biomechanical properties of the ECM influence cancer cell plasticity and vice versa. Outstanding challenges for the field remain the identification of the cellular mechanisms by which cancer cells establish tumor-promoting ECM characteristics and delineating the key molecular mechanisms underlying ECM-induced cancer cell plasticity. Here we summarize the current state of understanding about the relationships between cancer cells and the main stromal cell types of the microenvironment that determine ECM characteristics, and the key molecular pathways that govern this three-way interaction to regulate cancer cell plasticity. We postulate that a comprehensive understanding of this dynamic system will be required to fully exploit opportunities for targeting the ECM regulators of cancer cell plasticity.

Cell adhesion is regulated by CDK1 during the cell cycle

In most tissues, anchorage-dependent growth and cell cycle progression are dependent on cells engaging extracellular matrices (ECMs) via integrin-receptor adhesion complexes. In a highly conserved manner, cells disassemble adhesion complexes, round up, and retract from their surroundings before division, suggestive of a primordial link between the cell cycle machinery and the regulation of cell adhesion to the ECM. In this study, we demonstrate that cyclin-dependent kinase 1 (CDK1) mediates this link. CDK1, in complex with cyclin A2, promotes adhesion complex and actin cytoskeleton organization during interphase and mediates a large increase in adhesion complex area as cells transition from G1 into S. Adhesion complex area decreases in G2, and disassembly occurs several hours before mitosis. This loss requires elevated cyclin B1 levels and is caused by inhibitory phosphorylation of CDK1-cyclin complexes. The inactivation of CDK1 is therefore the trigger that initiates remodeling of adhesion complexes and the actin cytoskeleton in preparation for rapid entry into mitosis.

Molecular mechanisms of the preventable causes of cancer in the United States

Annually, there are 1.6 million new cases of cancer and nearly 600,000 cancer deaths in the United States alone. The public health burden associated with these numbers has motivated enormous research efforts into understanding the root causes of cancer. These efforts have led to the recognition that between 40% and 45% of cancers are associated with preventable risk factors and, importantly, have identified specific molecular mechanisms by which these exposures modify human physiology to induce or promote cancer. The increasingly refined knowledge of these mechanisms, which we summarize here, emphasizes the need for greater efforts toward primary cancer prevention through mitigation of modifiable risk factors. It also suggests exploitable avenues for improved secondary prevention (which includes the development of therapeutics designed for cancer interception and enhanced techniques for noninvasive screening and early detection) based on detailed knowledge of early neoplastic pathobiology. Such efforts would complement the current emphasis on the development of therapeutic approaches to treat established cancers and are likely to result in far greater gains in reducing morbidity and mortality.

The therapeutic effect of miR-125b is enhanced by the prostaglandin endoperoxide synthase 2/cyclooxygenase 2 blockade and hampers ETS1 in the context of the microenvironment of bone metastasis

Bone is the most common site for breast cancer spread. In the pro-metastatic cell line 1833, derived from MDA-MB-231 breast adenocarcinoma cells, both hypoxia and hepatocyte growth factor (HGF) influence the effect of miR-125b on ETS proto-oncogene 1 transcription factor (ETS1). The effect of hypoxia inducible factor 1 alpha subunit (HIF1A), known to promote metastatic spread by upregulating prostaglandin endoperoxide synthase 2 (PTGS2), may be dampened by miR-125b targeting PTGS2. Here, we investigated whether miR-125b plays a role in breast cancer metastasis by measuring its activity in response to the chemotherapeutic agent NS-398 in a xenograft model. NS-398 is typically used in the clinic to target PTGS2. We also aimed to describe the molecular mechanisms in vitro, since the enhancement of epithelial properties may favor the efficacy of therapies. We report that in the xenograft model, miR-125b reduced metastasis to the bone. We also report suppression of PTGS2 enhanced survival by decreasing HIF1A in cells within the bone marrow. In 1833 cells transfected with a miR-125b mimic we observed several phenotypic changes including enhancement of the epithelial marker E-cadherin, a reduction of mesenchymal-associated genes and a reduction of WNT-associated stem cell signaling. Our findings suggest that in vivo, key players of the bone microenvironment promoting breast cancer spread are regulated by miR-125b. In future, biological molecules imitating miR-125b may enhance the sensitivity of chemotherapeutic agents used to counteract bone metastases.

Prognostic role of matrix metalloproteinases in bladder carcinoma: a systematic review and meta-analysis

Recent studies have shown that matrix metalloproteinases (MMPs) might be a biomarker for predicting outcomes of bladder cancer. However, the prognostic value of overexpression of MMPs in bladder cancer is debatable and the studies are inconsistent. Therefore, this meta-analysis was performed to clarify the specific association and prognostic value of overexpression of MMPs in bladder carcinoma. Relevant studies were identified by searching PubMed, EMBASE, and the Web of Science. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) for disease-specific survival (DSS), overall survival (OS), disease/recurrence-free survival (DFS/RFS), and progression/metastasis-free survival (PFS/MFS) were analyzed to determine the prognostic value of MMPs. In total, eighteen applicable studies were included in this meta-analysis. We found that high expression of MMPs significantly correlated with a poor DSS and OS (HR=1.66; 95% CI = 1.38–2.01 and HR= 1.67; 95%CI= 1.26–2.22). MMPs also predicted tumor progression and metastasis with a pooled HR of 3.03 (95% CI 1.98–4.64). However, high MMPs expression had no pivotal impact on DFS/RFS (HR= 1.21; 95% CI= 0.96–1.53). With the purpose of better understanding the prognostic role of MMPs in patients wirh bladder carcinoma, we carried out this systematic review and meta-analysis.

Matricellular proteins and survival in patients with pancreatic cancer: A systematic review

Extracellular matrix (ECM) plays a fundamental role in tissue architecture and homeostasis and modulates cell functions through a complex interaction between cell surface receptors, hormones, several bioeffector molecules, and structural proteins like collagen. These components are secreted into ECM and all together contribute to regulate several cellular activities including differentiation, apoptosis, proliferation, and migration. The so-called "matricellular" proteins (MPs) have recently emerged as important regulators of ECM functions. The aim of our review is to consider all different types of MPs family assessing the potential relationship between MPs and survival in patients with pancreatic ductal adenocarcinoma (PDAC). A systematic computer-based search of published articles, according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) Statement issued in 2009 was conducted through Ovid interface, and literature review was performed in May 2017. The search text words were identified by means of controlled vocabulary, such as the National Library of Medicine's MESH (Medical Subject Headings) and Keywords. Collected data showed an important role of MPs in carcinogenesis and in PDAC prognosis even though the underlying mechanisms are still largely unknown and data are not univocal. Therefore, a better understanding of MPs role in regulation of ECM homeostasis and remodeling of specific organ niches may suggest potential novel extracellular targets for the development of efficacious therapeutic strategies.

Lysyl oxidase activates cancer stromal cells and promotes gastric cancer progression: quantum dot-based identification of biomarkers in cancer stromal cells

Purpose

Semiconductor quantum dots (QDs) are a promising alternative to organic fluorescent dyes for multiplexed molecular imaging of cancer stroma, which have great advantages in holistically analyzing the complex interactions among cancer stromal components in situ.

Patients and methods

A QD probe-based multiplexed spectral molecular imaging method was established for simultaneous imaging. Three tissue microarrays (TMAs) including 184 gastric cancer (GC) tissues were constructed for the study. Multispectral analyses were performed for quantifying stromal biomarkers, such as lysyl oxidase (LOX). The stromal status including infiltrating of immune cells (high density of macrophages), angiogenesis (high density of microvessel density [MVD], low neovessel maturation) and extracellular matrix (ECM) remodeling (low density of type IV collagen, intense expression of matrix metalloproteinase 9 [MMP-9]) was evaluated.

Results

This study compared the imaging features of the QD probe-based single molecular imaging method, immunohistochemistry, and organic dye-based immunofluorescent methods, and showed the advantages of the QD probe-based multiple molecular imaging method for simultaneously visualizing complex components of cancer stroma. The risk of macrophages in high density, high MVD, low neomicrovessel maturation, MMP-9 expression and low type IV collagen was significantly increased for the expression of LOX. With the advantages of the established QD probe-based multiplexed molecular imaging method, the spatial relationship between LOX and stromal essential events could be simultaneously evaluated histologically. Stromal activation was defined and then evaluated. Survival analysis showed that the stromal activation was correlated with overall survival and disease-free survival (P<0.001 for all). The expression of LOX was significantly increased in the intense activation subgroup (P<0.001).

Conclusion

Quantifying assessment of the stroma indicates that the LOX may be a stromal marker for GC and stromal activation, which is not only responsible for the ECM remodeling morphologically, but also for the formation of invasive properties and recurrence. These results support the possibility to integrate morphological and molecular biomarker information for cancer research by the biomedical application of QDs.

Harnessing the heart's resistance to malignant tumors: cardiac-derived extracellular vesicles decrease fibrosarcoma growth and leukemia-related mortality in rodents

The heart is known for its resistance to cancer. Although different conjectures have been proposed to explain this phenomenon, none has been tested. We propose that the heart microenvironment may exert anti-cancer properties. So, our objective was to test the anti-oncogenic potential of cardiac-derived extracellular vesicles (EVs). For that EVs secreted by cardiosphere-derived cells (CDCs, heart progenitor cells) were tested in vitro on fibrosarcoma HT1080. In vivo models comprised the xenograft HT1080 fibrosarcoma in athymic mice (n=35), and spontaneous acute lymphocyte leukemia in old rats (n=44). CDC-EVs were compared with two control groups: EVs secreted by bone-marrow derived mesenchymal stem cells (MSC-EVs) and phosphate-buffered saline (PBS). Injection of CDC-EVs led to a 2.5-fold decrease of fibrosarcoma growth in mice (p<0.01 and p<0.05 for human and rat EVs, respectively) vs PBS group. The effect was associated with 2-fold decrease of tumor cells proliferation (p<0.001) and 1.5-fold increase of apoptosis (p<0.05) in CDC-EV vs PBS mice. Salutary changes in tumor gene and protein expression were observed in CDC-EV animals. CDC-EVs reduced tumor vascularization compared with PBS (p<0.05) and MSC-EVs (p<0.01). Moreover, CDC-EVs increased leukemia-free survival (p<0.05) in old rats vs PBS. MiR-146, highly enriched in CDC-EVs, may be implicated in part of the observed effects. In conclusion, this study presents the first evidence that ties together the long-recognized enigma of the "heart immunity to cancer" with an antioncogenic effect of heart-derived EVs. These findings open up cancer as a new therapeutic target for CDC-EVs.

The crosstalk between lncRNA and microRNA in cancer metastasis: orchestrating the epithelial-mesenchymal plasticity

Noncoding RNAs (ncRNAs) have been demonstrated to closely associate with gene regulation and encompass the well-known microRNAs (miRNAs), as well as the most recently acknowledged long noncoding RNAs (lncRNAs). Current evidence indicates that lncRNAs can interact with miRNAs and these interactions play crucial roles in cancer metastasis, through regulating critical events especially the epithelial-mesenchymal transition (EMT). This review summarizes the types of lncRNA-miRNA crosstalk identified to-date and discusses their influence on the epithelial-mesenchymal plasticity and clinical metastatic implication.

Density-Dependent Regulation of Glioma Cell Proliferation and Invasion Mediated by miR-9

The phenotypic axis of invasion and proliferation in malignant glioma cells is a well-documented phenomenon. Invasive glioma cells exhibit a decreased proliferation rate and a resistance to apoptosis, and invasive tumor cells dispersed in brain subsequently revert to proliferation and contribute to secondary tumor formation. One miRNA can affect dozens of mRNAs, and some miRNAs are potent oncogenes. Multiple miRNAs are implicated in glioma malignancy, and several of which have been identified to regulate tumor cell motility and division. Using rat 9 L gliosarcoma and human U87 glioblastoma cell lines, we investigated miRNAs associated with the switch between glioma cell invasion and proliferation. Using micro-dissection of 9 L glioma tumor xenografts in rat brain, we identified disparate expression of miR-9 between cells within the periphery of the primary tumor, and those comprising tumor islets within the invasive zone. Modifying miR-9 expression in in vitro assays, we report that miR-9 controls the axis of glioma cell invasion/proliferation, and that its contribution to invasion or proliferation is biphasic and dependent upon local tumor cell density. In addition, immunohistochemistry revealed elevated hypoxia inducible factor 1 alpha (HIF-1α) in the invasive zone as compared to the primary tumor periphery. We also found that hypoxia promotes miR-9 expression in glioma cells. Based upon these findings, we propose a hypothesis for the contribution of miR-9 to the dynamics glioma invasion and satellite tumor formation in brain adjacent to tumor.

Bulk pancreatic cancer cells can convert into cancer stem cells(CSCs) in vitro and 2 compounds can target these CSCs

Increasing evidence has confirmed the existence of cancer stem cells (CSCs) in both hematological malignancies and solid tumors. However, the origin of CSCs is still uncertain, and few agents have been capable of eliminating CSCs till now. The aim of this study was to investigate whether bulk pancreatic cancer cells could convert into CSCs under certain conditions and explore whether metformin and curcumin can kill pancreatic CSCs. Aspc1, Bxpc3 and Panc1 pancreatic cancer cells were cultured in stem cell culture medium (serum-free Dulbecco's modified Eagle medium/Nutrient Mixture F-12 containing basic fibroblast growth factor, epidermal growth factor, B27 and insulin) for 5 days and it was found that all the pancreatic cancer cells aggregated into spheres and expressed pancreatic cancer stem cell surface markers. Then characteristics of Panc1 sphere cells were analyzed and cytotoxicity assays were performed. The results show that Panc1 sphere cells exhibited CSC characteristics and were more resistant to conventional chemotherapy and more sensitive to metformin and curcumin than their parent cells. These findings suggested that bulk pancreatic cancer cells could acquire CSC characteristics under certain conditions, which may support the "yin-yang" model of CSCs (interconversion between bulk cancer cells and CSCs). These results also showed that metformin and curcumin could be candidate drugs for targeting pancreatic CSCs.

Heterogeneity of tumor cells in terms of cancer-initiating cells

Tumors derive from a single cell clone but consist of heterogeneous cell subpopulations with diverse features and functions. A limited number of subclones with a selective advantage can initiate tumors when inoculated into immunocompromised mice, and are called cancer-initiating cells (CICs). CICs can be isolated from the bulk of tumors on the basis of their characteristics, such as high reagent efflux, degradation of reactive oxygen species, and aldehyde dehydrogenase (ALDH) activity. Under normal conditions, new CICs are produced by existing CICs rather than non-CICs. However, under stress conditions, non-CICs can occasionally produce CICs, a phenomenon known as plasticity. The dynamic exchange between CICs and non-CICs may enable tumors to survive under unfavorable conditions. CICs are located in a small portion of tumors. This suggests that microenvironmental factors induce or inhibit the CIC phenotype, which might be regulated by intercellular signaling between tumor cells. This review describes isolation of CICs from tumor cell populations and the microenvironmental factors that regulate CIC phenotypes in uterine cancer and lymphoma.

Mechanical Signals Inhibit Growth of a Grafted Tumor In Vivo: Proof of Concept

In the past ten years, many studies have shown that malignant tissue has been “normalized” in vitro using mechanical signals. We apply the principles of physical oncology (or mechanobiology) in vivo to show the effect of a “constraint field” on tumor growth. The human breast cancer cell line, MDA MB 231, admixed with ferric nanoparticles was grafted subcutaneously in Nude mice. The magnetizable particles rapidly surrounded the growing tumor. Two permanent magnets located on either side of the tumor created a gradient of magnetic field. Magnetic energy is transformed into mechanical energy by the particles acting as “bioactuators”, applying a constraint field and, by consequence, biomechanical stress to the tumor. This biomechanical treatment was applied 2 hours/day during 21 days, from Day 18 to Day 39 following tumor implantation. The study lasted 74 days. Palpable tumor was measured two times a week. There was a significant in vivo difference between the median volume of treated tumors and untreated controls in the mice measured up to D 74 (D 59 + population): (529 [346; 966] mm³ vs 1334 [256; 2106] mm³; p = 0.015), treated mice having smaller tumors. The difference was not statistically significant in the group of mice measured at least to D 59 (D 59 population). On ex vivo examination, the surface of the tumor mass, measured on histologic sections, was less in the treated group, G1, than in the control groups: G2 (nanoparticles, no magnetic field), G3 (magnetic field, no nanoparticles), G4 (no nanoparticles, no magnetic field) in the D 59 population (Median left surface was significantly lower in G1 (5.6 [3.0; 42.4] mm², p = 0.005) than in G2 (20.8 [4.9; 34.3]), G3 (16.5 [13.2; 23.2]) and G4 (14.8 [1.8; 55.5]); Median right surface was significantly lower in G1 (4.7 [1.9; 29.2] mm², p = 0.015) than in G2 (25.0 [5.2; 55.0]), G3 (18.0 [14.6; 35.2]) and G4 (12.5 [1.5; 51.8]). There was no statistically significant difference in the day 59+ population. This is the first demonstration of the effect of stress on tumor growth in vivo suggesting that biomechanical intervention may have a high translational potential as a therapy in locally advanced tumors like pancreatic cancer or primary hepatic carcinoma for which no effective therapy is currently available.

Veterinary oncology: Biology, big data and precision medicine

Despite significant advances in both the understanding and the treatment of cancer, the disease remains one of high mortality and morbidity causes in all species. Increases in survival times in human cancer have increased significantly in the past 25 years but most of these increases have been through small incremental changes. For some cancers, e.g. pancreatic cancer, survival times have not increased significantly in over 100 years. In veterinary oncology, there have been major shifts in the management of cancer in companion animals. Increased availability of specialist centres, coupled with changing attitudes in owners and veterinarians, have meant improvements in veterinary cancer care borne from market pressures and increased awareness and understanding. In this review the changing face of cancer biology over the past 25 years will be examined, and the barriers to clinical progress in veterinary medicine considered. Finally, an optimistic view of the future will be presented with the prospect of greater control over this devastating disease.

Myeloid cell signatures in tumor microenvironment predicts therapeutic response in cancer

Tumor microenvironment (TME) consists of several immune and nonimmune cell populations including tumor cells. For many decades, experimental studies have depicted profound contribution of TME toward cancer progression and metastasis development. Several therapeutic strategies have been tested against TME through preclinical studies and clinical trials. Unfortunately, most of them have shown transient effect, and have largely failed due to aggressive tumor growth and without improving survival. Solid tumors are known to have a strong myeloid component (eg, tumor-associated macrophages) in tumor development. Recent data suggest that therapeutic responses in tumor are characterized by alterations in immune cell signatures, including tumor-associated myeloid cells. Polarized tumor-associated myeloid cells (M1–M2) are critical in impairing therapeutic effect and promoting tumor growth. The present review is intended to compile all the literatures related to the emerging contribution of different populations of myeloid cells in the development of tumor and therapeutic failures. Finally, we have discussed targeting of myeloid cell populations as a combination therapy with chemo-, targeted-, or radiation therapies.

Special cancer microenvironment in human colonic cancer: Concept of cancer microenvironment formed by peritoneal invasion (CMPI) and implication of subperitoneal fibroblast in cancer progression

Clinical outcomes of colorectal cancer are influenced not by tumor size, but by spread into the bowel wall. Although assessment of serosal involvement is an important pathological feature for classification of colon cancer, its diagnostic consistency has been questioned. Using elastic staining, we assessed elastic laminal invasion (ELI) for more objective stratification of deep tumor invasion around the peritoneal surface. In addition, pathological characteristic features of marked tumor budding, fibrosis, and macrophage infiltration in the tumor area with ELI was elucidated. This characteristic tumor area was termed cancer microenvironment formed by peritoneal elastic laminal invasion (CMPI). We elucidated histoanatomical layer-dependent heterogeneity of fibroblast in colonic tissue. Furthermore, subperitoneal fibroblasts (SPFs) play a crucial role in tumor progression and metastasis in CMPI. Our ELI and CMPI concept contributes not only to objective pathological diagnosis, but also sheds light on biological research of special cancer microenvironments detectable in human colorectal cancers. Herein, we describe the diagnostic utility of ELI and morphological alteration in advanced colorectal cancers to determine the phenomenon that occurs when tumors invade around the peritoneal surface. Next, biological research of CMPI is reviewed to stress the importance of pathological research to establish new biological concepts.

Reversal of liver cancer-associated stellate cell-induced stem-like characteristics in SMMC-7721 cells by 8-bromo-7-methoxychrysin via inhibiting STAT3 activation

Hepatic stellate cells (HSCs) that are activated by human hepatocellular carcinoma (HCC) cells secrete a variety of cytokines, which are the main component of the HCC microenvironment. We aimed to determine whether 8-bromo-7-methoxychrysin (BrMC) could interfere in cross-talk of the human hepatic stellate cell line LX-2 and liver cancer stem-like cells (LCSLCs) to inhibit the characteristics of LCSLCs endowed with the capacity of sustaining human hepatocellular carcinoma (HCC) self-renewal and progression, and to identify its potential mechanism of action. We found that the levels of fibroblast activation protein (FAP) were augmented in LX-2 cells treated with the conditioned medium of LCSLCs (LCSLC-CM) compared to those cultured with routine medium, indicating that the LCSLC-CM can activate LX-2 cells to become liver cancer-associated stellate cells (LCAHSCs). Furthermore, sphere forming capability of SMMC-7721 cells was enhanced and stem cell-related protein expression was significantly increased following treatment with the conditioned medium of LCAHSCs (LCAHSC-CM). Moreover, the level of p-STAT3 was increased in LX-2 cells treated with LCSLC-CM and BrMC reduced expression of p-STAT3. Combination of BrMC and the selective inhibitor of STAT3 cucurbitacin I (JSI-124) synergistically suppressed the LCSLC characteristics in SMMC-7721 cells. Collectively, our data showed that BrMC inhibited the interaction between LX-2 cells and HCC-derived CSCs, and did so potentially through modulation of the STAT3 pathway. Future therapeutic strategies employing anti-CSC therapy should confirm the potential of cucurbitacin I (JSI-124) and BrMC as potent therapeutic agents.

Investigating the Radioresistant Properties of Lung Cancer Stem Cells in the Context of the Tumor Microenvironment

Lung cancer is the most common cause of cancer-related deaths worldwide and non-small cell lung cancer (NSCLC) accounts for ~85% of all lung cancer. While recent research has shown that cancer stem cells (CSC) exhibit radioresistant and chemoresistant properties, current cancer therapy targets the bulk of the tumor burden without accounting for the CSC and the contribution of the tumor microenvironment. CSC interaction with the stroma enhances NSCLC survival, thus limiting the efficacy of treatment. The aim of this study was to elucidate the role of CSC and the microenvironment in conferring radio- or chemoresistance in an in vitro tumor model for NSCLC. The novel in vitro three-dimensional (3D) NSCLC model of color-coded tumor tissue analogs (TTA) that we have developed is comprised of human lung adenocarcinoma cells, fibroblasts, endothelial cells and NSCLC cancer stem cells maintained in low oxygen conditions (5% O2) to recapitulate the physiologic conditions in tumors. Using this model, we demonstrate that a single 5 Gy radiation dose does not inhibit growth of TTA containing CSC and results in elevated expression of cytokines (TGF-α, RANTES, ENA-78) and factors (vimentin, MMP and TIMP), indicative of an invasive and aggressive phenotype. However, combined treatment of single dose or fractionated doses with cisplatin was found to either attenuate or decrease the proliferative effect that radiation exposure alone had on TTA containing CSC maintained in hypoxic conditions. In summary, we utilized a 3D NSCLC model, which had characteristics of the tumor microenvironment and tumor cell heterogeneity, to elucidate the multifactorial nature of radioresistance in tumors.

Tumor-extracellular matrix interactions: Identification of tools associated with breast cancer progression

Several evidences support the concept that cancer development and progression are not entirely cancer cell-autonomous processes, but may be influenced, and possibly driven, by cross-talk between cancer cells and the surrounding microenvironment in which, besides immune cells, stromal cells and extracellular matrix (ECM) play a major role in regulating distinct biologic processes. Stroma and ECM-related signatures proved to influence breast cancer progression, and to contribute to the identification of tumor phenotypes resistant to cytotoxic and hormonal treatments. The possible clinical implications of the interplay between tumor cells and the microenvironment, with special reference to ECM remodelling, will be discussed in this review.

Low ATM protein expression in malignant tumor as well as cancer-associated stroma are independent prognostic factors in a retrospective study of early-stage hormone-negative breast cancer

INTRODUCTION

The serine/threonine protein kinase ataxia telangiectasia mutated (ATM) is critical in maintaining genomic integrity. Upon DNA double-strand breaks, ATM phosphorylates key downstream proteins including p53 and BRCA1/2, thereby orchestrating complex signaling pathways involved in cell cycle arrest, DNA repair, senescence and apoptosis. Although sporadic mutation of ATM occurs rarely in breast cancer, the status of its protein expression and its clinical significance in breast cancer remain not well established. Our study was designed to investigate the influence of ATM protein in both tumor and cancer-associated stroma on clinical outcome in hormone-positive (HPBC) and hormone-negative (HNBC) early-stage breast cancer (EBC).

METHODS

Tissue microarrays (TMAs), containing formalin-fixed, paraffin-embedded resected tumors from two cohorts of patients (HPBC cohort: n=130; HNBC cohort: n=168) diagnosed at the Tom Baker Cancer Centre, Calgary, Canada, were analyzed for ATM protein expression using fluorescence immunohistochemistry (IHC) and automated quantitative analysis (AQUA). ATM expression levels were measured within the tumor as a whole (tATM) as indicated by pan-cytokeratin expression, tumor nuclear compartment (nATM) as indicated by both DAPI and pan-cytokeratin-positive results, and cancer-associated stroma (csATM) as indicated by vimentin-positive and pan-cytokeratin-negative results. ATM expression levels within these compartments were correlated with clinical outcome.

RESULTS

While tATM and nATM were significantly lower in tumors compared to normal breast epithelial tissues, csATM was significantly higher than the corresponding normal tissue compartment. In addition, the median expression level of both tATM and nATM were two- to threefold lower (P<0.001) in HNBC than in HPBC. In both HNBC and HPBC cohorts, patients with low tATM, nATM and csATM tumors had significantly poorer survival outcomes than those with a high tATM, nATM and csATM, but this effect was more pronounced in HNBC. A multivariate analysis demonstrates that these biomarkers predict survival independent of tumor size and lymph node status, but only in the HNBC cohort (P<0.001).

CONCLUSIONS

Low ATM protein expression in both malignant tumor and stromal compartments likely contributes to the aggressive nature of breast cancer and is an independent prognostic factor associated with worse survival in HNBC patients.

Cancer-associated mesenchymal stem cells aggravate tumor progression

Mesenchymal stem cells (MSCs) have both stemness and multi-modulatory activities on other cells, and the immunosuppressive and tumor-promotive mechanisms have been intensively investigated in cancer. The role of MSCs appears to be revealed in tumor aggravation, and targeting MSCs seems to be a promising strategy for treating cancer patients. However, it is still impractical in clinical therapy, since the precise MSCs are poorly understood in the in vivo setting. In previous studies, MSCs were obtained from different sources, and were prepared by ex vivo expansion for a long term. The inconsistent experimental conditions made the in vivo MSCs obscure. To define the MSCs in the host is a priority issue for targeting MSCs in cancer therapy. We recently identified a unique subpopulation of MSCs increasing in mice and human with cancer metastasis. These MSCs are specifically expanded by metastatic tumor cells, and promote tumor progression and dissemination accompanied by immune suppression and dysfunction in the host, more powerfully than normal MSCs growing without interference of cancer. In this review, we summarize current knowledge of the role of MSCs in tumor aggravation, along with our new findings of the bizarre MSCs.