MSC-regulated microRNAs converge on the transcription factor FOXP2 and promote breast cancer metastasis

The Role of Breast Cancer Stem Cell-Related Biomarkers as Prognostic Factors

Breast cancer is one of the leading causes of cancer-related deaths in women worldwide, and its incidence is on the rise. A small fraction of cancer stem cells was identified within the tumour bulk, which are regarded as cancer-initiating cells, possess self-renewal and propagation potential, and a key driver for tumour heterogeneity and disease progression. Cancer heterogeneity reduces the overall efficacy of chemotherapy and contributes to treatment failure and relapse. The cell-surface and subcellular biomarkers related to breast cancer stem cell (BCSC) phenotypes are increasingly being recognised. These biomarkers are useful for the isolation of BCSCs and can serve as potential therapeutic targets and prognostic tools to monitor treatment responses. Recently, the role of noncoding microRNAs (miRNAs) has extensively been explored as novel biomarker molecules for breast cancer diagnosis and prognosis with high specificity and sensitivity. An in-depth understanding of the biological roles of miRNA in breast carcinogenesis provides insights into the pathways of cancer development and its utility for disease prognostication. This review gives an overview of stem cells, highlights the biomarkers expressed in BCSCs and describes their potential role as prognostic indicators.

lncRNA-miRNA-mRNA interaction network for colorectal cancer; An in silico analysis

BACKGROUND

Colorectal cancer (CRC) is one of the most frequent and diagnosed diseases. Accumulating evidences showed that mRNAs and noncoding RNAs play important regulatory roles in tumorigenesis. Identification and determining the relationship between them can help diagnosis and treatment of cancer.

METHODS

Here we analyzed three microarray datasets; GSE110715, GSE32323 and GSE21510, to identify differentially expressed lncRNAs and mRNAs in CRC. The adjusted p-value ≤0.05 was considered statistically significant. Gene set enrichment analysis was carried out using DAVID tool. The miRCancer database was searched to obtain differentially expressed miRNAs in colorectal cancer, and the miRDB database was used to attain the targets of the obtained miRNAs. To predict the lncRNA-miRNA interactions we used DIANA-LncBase v2 and RegRNA 2.0. Finally the lncRNA-miRNA-mRNA-signaling pathway network was constructed using Cytoscape v3.1.

RESULTS

By analyzing the three datasets, a total of 21 mRNAs (15 up- and 6 down-regulated) and 24 lncRNAs (18 up- and 6 down-regulated) were identified as common differentially expressed genes between CRC tumor and marginal tissues. Nevertheless, the constructed lncRNA-miRNA-mRNA-signaling pathway network revealed a convergence on 6 lncRNAs (3 up- and 3 downregulated), 7 mRNAs (2 up- and 5 downregulated) and 6 miRNAs (3 up- and 3 downregulated). We found that dysregulation of lncRNAs such as PCBP1-AS1, UCA1 and SNHG16 could sequester several miRNAs such as hsa-miR-582-5p and hsa-miR-198 and promote the proliferation, invasion and drug resistance of colorectal cancer cells.

CONCLUSIONS

We introduced a set of lncRNAs, mRNAs and miRNAs differentially expressed in CRC which might be considered for further experimental research as potential biomarkers of CRC development.

Bone Marrow Mesenchymal Stem Cells Promote the Stemness of Hypopharyngeal Cancer Cells

A study was to investigate the regulation of bone marrow mesenchymal stem cells (BMSCs) on the stemness of hypopharyngeal cancer cells (FaDu cells). Green fluorescent protein-labeled FaDu cells were cocultured with BMSCs and then were isolated. In vitro experiments, including cell cycle and apoptosis analyses and clonogenic and sphere formation assays, were conducted using the cocultured FaDu cells to determine the stemness of FaDu cells. The tumor formation assay was performed through subcutaneous injection of FaDu cells into nude mice to determine the tumorigenic ability of FaDu cells after coculture. Immunohistochemical analysis of CD44 and ALDH1 was performed on the tumor tissue. After coculturing with human BMSCs, the ratio of FaDu cells at G2 phase was increased, while the ratios at S and G1 phases were decreased. In addition, coculture reduced apoptosis, but increased the clonogenic ability and sphere formation efficiency of FaDu cells. Finally, coculturing FaDu cells induced more robust and faster tumor formation as well as increased expression levels of CD44 and ALDH1 in tumor tissue. BMSCs promote the stemness of hypopharyngeal cancer cells.

Potential miRNAs for miRNA-Based Therapeutics in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNAs that can post-transcriptionally regulate the genes involved in critical cellular processes. The aberrant expressions of oncogenic or tumor suppressor miRNAs have been associated with cancer progression and malignancies. This resulted in the dysregulation of signaling pathways involved in cell proliferation, apoptosis and survival, metastasis, cancer recurrence and chemoresistance. In this review, we will first (i) provide an overview of the miRNA biogenesis pathways, and in vitro and in vivo models for research, (ii) summarize the most recent findings on the roles of microRNAs (miRNAs) that could potentially be used for miRNA-based therapy in the treatment of breast cancer and (iii) discuss the various therapeutic applications.

Multiple Dynamics in Tumor Microenvironment Under Radiotherapy

The tumor microenvironment (TME) is an evolutionally low-level and embryonically featured tissue comprising heterogenic populations of malignant and stromal cells as well as noncellular components. Under radiotherapy (RT), the major modality for the treatment of malignant diseases [1], TME shows an adaptive response in multiple aspects that affect the efficacy of RT. With the potential clinical benefits, interests in RT combined with immunotherapy (IT) are intensified with a large scale of clinical trials underway for an array of cancer types. A better understanding of the multiple molecular aspects, especially the cross talks of RT-mediated energy reprogramming and immunoregulation in the irradiated TME (ITME), will be necessary for further enhancing the benefit of RT-IT modality. Coming studies should further reveal more mechanistic insights of radiation-induced instant or permanent consequence in tumor and stromal cells. Results from these studies will help to identify critical molecular pathways including cancer stem cell repopulation, metabolic rewiring, and specific communication between radioresistant cancer cells and the infiltrated immune active lymphocytes. In this chapter, we will focus on the following aspects: radiation-repopulated cancer stem cells (CSCs), hypoxia and re-oxygenation, reprogramming metabolism, and radiation-induced immune regulation, in which we summarize the current literature to illustrate an integrated image of the ITME. We hope that the contents in this chapter will be informative for physicians and translational researchers in cancer radiotherapy or immunotherapy.

The versatile roles and clinical implications of exosomal mRNAs and microRNAs in cancer

Extracellular vesicles (EVs), which include exosomes, microvesicles, and apoptotic bodies, are nanosized structures that are secreted by various cells and act as important mediators in intercellular communication. Recent studies have shown that exosomes carrying bioactive molecules are generated from multivesicular bodies and are present in various body fluids. mRNAs and microRNAs (miRNAs) are encapsulated in exosomes and have been found to be involved in multiple pathophysiological processes. Here, we provide a review of tumor-associated exosomal mRNAs and miRNAs and their roles in metastasis and drug resistance. In particular, we emphasize their clinical application potential as diagnostic and prognostic biomarkers of cancer and in cancer therapy.

Mouse bone marrow mesenchymal stem cells with distinct p53 statuses display differential characteristics

Mesenchymal stem cells (MSCs) affect diverse aspects of tumor progression, such as angiogenesis, tumor growth and metastasis. Bone marrow MSCs (BM‑MSCs) are fibroblast‑like cells with multipotent differentiation ability, that localize to areas of tissue damage, including wounds and solid tumors. The tumor suppressor gene, p53, is functionally involved in cell cycle control, apoptosis and genomic stability, and is mutated and inactivated in most human cancers. The present study aimed to investigate the role of p53 in the biology of BM‑MSCs. In the present study, p53 wild‑type (p53+/+), knockdown (p53+/‑) and knockout (p53‑/‑) mouse BM‑MSCs (mBM‑MSCs) were observed to be similar in appearance and in the expression of cell surface biomarkers, but expressed differential p53 protein levels. The p53+/‑ and p53‑/‑ mBM‑MSCs demonstrated an increased proliferation rate compared with mBM‑MSCs derived from p53+/+ mice. mBM‑MSCs from all three groups, representing distinct p53 statuses, were unable to form tumors over a 3‑month period in vivo. The adipogenic and osteogenic differentiation of mBM‑MSCs was increased in the absence of p53. The colony formation and migratory abilities of p53+/‑ and p53‑/‑ mBM‑MSCs were markedly enhanced, and the expression levels of stem cell‑associated proteins were significantly increased compared with p53+/+. The expression levels of microRNA (miR)‑3152 and miR‑337 were significantly increased in p53+/‑ and p53‑/‑ mBM‑MSCs, whereas the expression levels of miR‑221, miR‑155, miR‑1288 and miR‑4669 were significantly decreased. The expression levels of tumor necrosis factor‑α and interferon‑γ‑inducible protein‑10 were significantly upregulated in the supernatant of p53+/‑ and p53‑/‑ mBM‑MSCs. Ubiquitin protein ligase E3 component n‑recognin 2, RING‑finger protein 31 and matrix metalloproteinase 19 were highly expressed in p53+/‑ and p53‑/‑ mBM‑MSCs. The results of the present study indicated that p53 may serve an important role in the biology of mBM‑MSCs, and may provide novel insights into the role of cells with different p53 statuses in cancer progression.

Hepatic stellate cells promote the progression of hepatocellular carcinoma through microRNA-1246-RORα-Wnt/β-Catenin axis

Hepatic stellate cells (HSCs) play vital roles in tumorigenesis and progression of hepatocellular carcinoma (HCC). However, there remains a lack of high-throughput studies on gene expression alterations in HCC cells in response to direct interactions with HSCs. In this study, we established a direct co-culture model of HSCs and HCC cells. We found that the expression of a set of miRNAs, most notably miR-1246, was triggered by HSCs. RORα was confirmed as the target gene of miR-1246. Either overexpression of miR-1246 or knockdown of RORα enhanced the proliferation, invasiveness, and metastatic capability of HCC both in vitro and in vivo, through Wnt/β-catenin pathway activation and promotion of epithelial-mesenchymal transition (EMT). Moreover, upregulation of miR-1246 and repression of RORα were prominent features of aggressive clinical HCC. The miR-1246-RORα-Wnt/β-catenin axis is a novel pathway through which HSCs accelerate HCC progression.

An evolving paradigm of cancer stem cell hierarchies: therapeutic implications

Over a decade of research has confirmed the critical role of cancer stem-like cells (CSCs) in tumor initiation, chemoresistance, and metastasis. Increasingly, CSC hierarchies have begun to be defined with some recurring themes. This includes evidence that these hierarchies are 'flexible,' with both cell state transitions and dedifferentiation events possible. These findings pose therapeutic hurdles and opportunities. Here, we review cancer stem cell hierarchies and their interactions with the tumor microenvironment. We also discuss the current therapeutic approaches designed to target CSC hierarchies and initial clinical trial results for CSC targeting agents. While cancer stem cell targeted therapies are still in their infancy, we are beginning to see encouraging results that suggest a positive outlook for CSC-targeting approaches.

The genetic script of metastasis

Metastasis is a pivotal event that changes the course of cancers from benign and treatable to malignant and difficult to treat, resulting in the demise of patients. Understanding the genetic control of metastasis is thus crucial to develop efficient and sustainable targeted therapies. Here we discuss the alterations in epigenetic mechanisms, transcription, chromosomal instability, chromosome imprinting, non-coding RNAs, coding RNAs, mutant RNAs, enhancers, G-quadruplexes, and copy number variation to dissect the genetic control of metastasis. We conclude that the genetic control of metastasis is predominantly executed through epithelial to mesenchymal transition and evasion of cell death. We discuss how genetic regulatory mechanisms can be harnessed for therapeutic purposes to achieve sustainable control over cancer metastasis.

The MicroRNA-23b/27b/24 Cluster Facilitates Colon Cancer Cell Migration by Targeting FOXP2

Acquisition of cell migration capacity is an early and essential process in cancer development. The aim of this study was to identify microRNA gene expression networks that induced high migration capacity. Using colon cancer HCT116 cells subcloned by transwell-based migrated cell selection, microRNA array analysis was performed to examine the microRNA expression profile. Promoter activity and microRNA targets were assessed with luciferase reporters. Cell migration capacity was assessed by either the transwell or scratch assay. In isolated subpopulations with high migration capacity, the expression levels of the miR-23b/27b/24 cluster increased in accordance with the increased expression of the short C9orf3 transcript, a host gene of the miR-23b/27b/24 cluster. E2F1-binding sequences were involved in the basic transcription activity of the short C9orf3 expression, and E2F1-small-interfering (si)RNA treatment reduced the expression of both the C9orf3 and miR-23b/27b/24 clusters. Overexpression experiments showed that miR-23b and miR-27b promoted cell migration, but the opposite effect was observed with miR-24. Forkhead box P2 (FOXP2) mRNA and protein levels were reduced by both/either miR-23b and miR-27b. Furthermore, FOXP2 siRNA treatment significantly promoted cell migration. Our findings demonstrated a novel role of the miR-23b/27b/24 cluster in cell migration through targeting FOXP2, with potential implications for the development of microRNA-based therapy targeted at inhibiting cancer migration.

Role of microRNAs in remodeling the tumor microenvironment (Review)

MicroRNAs (miRNAs) are short non-coding RNAs that are known to regulate gene expression at the post-transcriptional level. miRNA expression is often deregulated in several human cancers, affecting the communication between tumor stroma and tumor cells, among other functions. Understanding the role of miRNAs in the tumor microenvironment is crucial for fully elucidating the molecular mechanisms underlying tumor progression and exploring novel diagnostic biomarkers and therapeutic targets. The present review focused on the role of miRNAs in remodeling the tumor microenvironment, with an emphasis on their impact on tumor growth, metastasis and resistance to treatment, as well as their potential clinical applications.

Molecular networks of FOXP family: dual biologic functions, interplay with other molecules and clinical implications in cancer progression

Though Forkhead box P (FOXP) transcription factors comprising of FOXP1, FOXP2, FOXP3 and FOXP4 are involved in the embryonic development, immune disorders and cancer progression, the underlying function of FOXP3 targeting CD4 + CD25+ regulatory T (Treg) cells and the dual roles of FOXP proteins as an oncogene or a tumor suppressor are unclear and controversial in cancers to date. Thus, the present review highlighted research history, dual roles of FOXP proteins as a tumor suppressor or an oncogene, their molecular networks with other proteins and noncoding RNAs, cellular immunotherapy targeting FOXP3, and clinical implications in cancer progression.

A novel panel of differentially-expressed microRNAs in breast cancer brain metastasis may predict patient survival

Breast cancer brain metastasis (BCBM) is an area of unmet clinical need. MicroRNAs (miRNAs) have been linked to the metastatic process in breast cancer (BC). In this study, we aim to determine differentially-expressed miRNAs utilising primary BCs that did not relapse (BCNR, n = 12), primaries that relapsed (BCR) and their paired (n = 40 pairs) brain metastases (BM) using the NanoString™ nCounter™ miRNA Expression Assays. Significance analysis of microarrays identified 58 and 11 differentially-expressed miRNAs between BCNR vs BCR and BCR vs BM respectively and pathway analysis revealed enrichment for genes involved in invasion and metastasis. Four miRNAs, miR-132-3p, miR-199a-5p, miR-150-5p and miR-155-5p, were differentially-expressed within both cohorts (BCNR-BCR, BCR-BM) and receiver-operating characteristic curve analysis (p = 0.00137) and Kaplan-Meier survival method (p = 0.0029, brain metastasis-free survival; p = 0.0007, overall survival) demonstrated their potential use as prognostic markers. Ingenuity pathway enrichment linked them to the MET oncogene, and the cMET protein was overexpressed in the BCR (p < 0.0001) and BM (p = 0.0008) cases, compared to the BCNRs. The 4-miRNAs panel identified in this study could be potentially used to distinguish BC patients with an increased risk of developing BCBM and provide potential novel therapeutic targets, whereas cMET-targeting warrants further investigation in the treatment of BCBM.

MicroRNAs Involved in Carcinogenesis, Prognosis, Therapeutic Resistance and Applications in Human Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive, prevalent, and distinct subtype of breast cancer characterized by high recurrence rates and poor clinical prognosis, devoid of both predictive markers and potential therapeutic targets. MicroRNAs (miRNA/miR) are a family of small, endogenous, non-coding, single-stranded regulatory RNAs that bind to the 3′-untranslated region (3′-UTR) complementary sequences and downregulate the translation of target mRNAs as post-transcriptional regulators. Dysregulation miRNAs are involved in broad spectrum cellular processes of TNBC, exerting their function as oncogenes or tumor suppressors depending on their cellular target involved in tumor initiation, promotion, malignant conversion, and metastasis. In this review, we emphasize on masses of miRNAs that act as oncogenes or tumor suppressors involved in epithelial–mesenchymal transition (EMT), maintenance of stemness, tumor invasion and metastasis, cell proliferation, and apoptosis. We also discuss miRNAs as the targets or as the regulators of dysregulation epigenetic modulation in the carcinogenesis process of TNBC. Furthermore, we show that miRNAs used as potential classification, prognostic, chemotherapy and radiotherapy resistance markers in TNBC. Finally, we present the perspective on miRNA therapeutics with mimics or antagonists, and focus on the challenges of miRNA therapy. This study offers an insight into the role of miRNA in pathology progression of TNBC.

MiR-9-5p Inhibits Glioblastoma Cells Proliferation Through Directly Targeting FOXP2 (Forkhead Box P2)

Glioblastoma (GBM) is the most malignant tumor in the central nervous system and the treatment is still unsatisfactory because the mechanism of the disease remains unclear. The abnormal expression of miRNAs and its target proteins play a crucial role in the development of glioblastoma. In this study, we demonstrated that high expression of miR-9-5p and low expression of forkhead box P2 (FOXP2) were related with better outcome in patients with GBM, and down regulated FOXP2 expression was able to inhibit glioma cells proliferation by cell cycle arrest. Furthermore, we found that FOXP2 was the target protein of miR-9-5p in luciferase assay. The results of this study suggest a novel regulatory mechanism that miR-9-5p can inhibit glioma cells proliferation by downregulating FOXP2.

NEDD9 Inhibition by miR-25-5p Activation Is Critically Involved in Co-Treatment of Melatonin- and Pterostilbene-Induced Apoptosis in Colorectal Cancer Cells

The underlying interaction between melatonin (MLT) and daily fruit intake still remains unclear to date, despite multibiological effects of MLT. Herein, the apoptotic mechanism by co-treatment of MLT and pterostilbene (Ptero) contained mainly in grape and blueberries was elucidated in colorectal cancers (CRCs). MLT and Ptero co-treatment (MLT+Ptero) showed synergistic cytotoxicity compared with MLT or Ptero alone, reduced the number of colonies and Ki67 expression, and also increased terminal deoxynucleotidyl transferase dUTP nick end labeling- (TUNEL) positive cells and reactive oxygen species (ROS) production in CRCs. Consistently, MLT+Ptero cleaved caspase 3 and poly (ADP-ribose) polymerase (PARP), activated sex-determining region Y-Box10 (SOX10), and also attenuated the expression of Bcl-xL, neural precursor cell expressed developmentally downregulated protein 9 (NEDD9), and SOX9 in CRCs. Additionally, MLT+Ptero induced differentially expressed microRNAs (upregulation: miR-25-5p, miR-542-5p, miR-711, miR-4725-3p, and miR-4484; downregulation: miR-4504, miR-668-3p, miR-3121-5p, miR-195-3p, and miR-5194) in HT29 cells. Consistently, MLT +Ptero upregulated miR-25-5p at mRNA level and conversely NEDD9 overexpression or miR-25-5p inhibitor reversed the ability of MLT+Ptero to increase cytotoxicity, suppress colony formation, and cleave PARP in CRCs. Furthermore, immunofluorescence confirmed miR-25-5p inhibitor reversed the reduced fluorescence of NEDD9 and increased SOX10 by MLT+Ptero in HT29 cells. Taken together, our findings provided evidence that MLT+Ptero enhances apoptosis via miR-25-5p mediated NEDD9 inhibition in colon cancer cells as a potent strategy for colorectal cancer therapy.

Stem cells in tissues, organoids, and cancers

Stem cells give rise to all cells and build the tissue structures in our body, and heterogeneity and plasticity are the hallmarks of stem cells. Epigenetic modification, which is associated with niche signals, determines stem cell differentiation and somatic cell reprogramming. Stem cells play a critical role in the development of tumors and are capable of generating 3D organoids. Understanding the properties of stem cells will improve our capacity to maintain tissue homeostasis. Dissecting epigenetic regulation could be helpful for achieving efficient cell reprograming and for developing new drugs for cancer treatment. Stem cell-derived organoids open up new avenues for modeling human diseases and for regenerative medicine. Nevertheless, in addition to the achievements in stem cell research, many challenges still need to be overcome for stem cells to have versatile application in clinics.

Microenvironmental Regulation of Long Noncoding RNA LINC01133 Promotes Cancer Stem Cell-Like Phenotypic Traits in Triple-Negative Breast Cancers

The fibrotic tumor microenvironment is a critical player in the pathogenesis of triple-negative breast cancers (TNBCs), with the presence of fibroblastic infiltrates particularly correlating with tumors that are clinically advanced. On this front, we previously demonstrated that TNBCs are highly enriched in fibroblastic stromal progenitor cells called mesenchymal stem/stromal cells (MSCs) and that such cells play critical roles in promoting TNBC initiation and progression. How TNBC cells respond to MSC stimulation, however, is not fully understood, and stands to reveal contextual signals used by TNBC cells during tumor development and provide biomarkers and therapeutic targets of pertinence to TNBC management. Here, we report that MSCs strongly induced the long noncoding RNA (lncRNA) LINC01133 in neighboring TNBC cells. Indeed, although lncRNAs have been tightly associated with cancer development, their contributions to breast cancer in general, and to TNBC pathogenesis in particular, have not been fully elucidated, and we set out to determine if LINC01133 regulated malignant traits in TNBC cells. We establish that LINC01133 is sufficient, on its own, in promoting phenotypic and growth characteristics of cancer stem cell-like cells, and that it is a direct mediator of the MSC-triggered miR-199a-FOXP2 pathway in TNBC models. Furthermore, we show that LINC01133 is a critical regulator of the pluripotency-determining gene Kruppel-Like Factor 4 (KLF4), and that it represents a biomarker and prognosticator of disease outcome in the clinic. Collectively, our findings introduce LINC01133 as a novel functional driver of malignancy and a potential theranostic in TNBC. Stem Cells 2019;37:1281-1292.

Upregulated microRNA‑671‑3p promotes tumor progression by suppressing forkhead box P2 expression in non‑small‑cell lung cancer

In the present study, the expression of microRNA (miR)‑671‑3p in non‑small‑cell lung cancer (NSCLC) was detected via reverse transcription‑quantitative polymerase chain reaction analysis, and its role in cell proliferation, apoptosis, migration and invasion was investigated via Cell Counting Kit‑8, colony formation, flow cytometry, Transwell and scratch assays, respectively. It was observed that the expression of miR‑671‑3p was upregulated in NSCLC tissues and cell lines (A549 and H1975). Treatment with miR‑671‑3p inhibitors suppressed cell proliferation, migration and invasion, and increased apoptosis in vitro, suggesting that miR‑671‑3p functions as an oncogene in NSCLC. In addition, forkhead box P2 (FOXP2) has been reported to be a tumor suppressor that is downregulated in several types of cancer, and its low expression was confirmed in NSCLC tissues and cell lines in the current study via western blotting. The results of the luciferase reporter assay also demonstrated that miR‑671‑3p targeted directly the 3'‑untranslated region of FOXP2. Furthermore, overexpression of FOXP2 in A549 and H1975 cell lines suppressed the growth, migration and invasion, and promoted apoptosis, whereas these effects were reversed by transfection with miR‑671‑3p mimics, suggesting that miR‑671‑3p promoted tumor progression via regulating FOXP2. Taken together, the results reported in the present study implied that miR‑671‑3p may be a potential therapeutic target in NSCLC.

Recruitment of stromal cells into tumour microenvironment promote the metastatic spread of breast cancer

Currently, metastasis remains the primary cause of death of patients with breast cancer despite the important advances in the treatment of this disease. In the complex tumour microenvironment network, several malignant and non-malignant cell types as well as components of extracellular matrix cooperate in promoting the metastatic spread of breast carcinoma. Many components of the stromal compartment are recruited from distant sites to the tumour including mesenchymal stem cells, endothelial cells, macrophages and other immune cells whereas other cells such as fibroblasts are already present in both primary and secondary lesions. When these cells come into contact with cancer cells they are "educated" and acquire a pro-tumoural phenotype, which support all the steps of the metastatic cascade. In this Review, we highlight the role played by each stromal component in guiding cancer cells in their venture towards colonizing metastatic sites.

Defining the "Metastasome": Perspectives from the genome and molecular landscape in colorectal cancer for metastasis evolution and clinical consequences

Metastasis still poses the highest challenge for personalized therapy in cancer, partly due to a still incomplete understanding of its molecular evolution. We recently presented the most comprehensive whole-genome study of colorectal metastasis vs. matched primary tumors and suggested novel components of disease progression and metastasis evolution, some of them potentially relevant for targeted therapy. In this review, we try to put these findings into perspective with latest discoveries of colleagues and recent literature, and propose a systematic international team effort to collectively define the "metastasome", a term we introduce to summarize all genomic, epigenomic, transcriptomic, further -omic, molecular and functional characteristics rendering metastases different from primary tumors. Based on recent discoveries, we propose a revised metastasis model for colorectal cancer which is based on a common ancestor clone, early dissemination but flexible early or late stage clonal separation paralleling stromal interactions. Furthermore, we discuss hypotheses on site-specific metastasis, colorectal cancer progression, metastasis-targeted diagnosis and therapy, and metastasis prevention based on latest metastasome data.

Cancer stem cells in breast and prostate: Fact or fiction?

Since the introduction of the cancer stem cell (CSC) hypothesis, accumulating evidence shows that most cancers present stem-like niches. However, therapies aimed at targeting this niche have not been as successful as expected. New evidence regarding CSCs hierarchy, similarities with normal tissue stem cells and cell plasticity might be key in understanding their role in cancer biology and how to efficiently eliminate them. In this Chapter, we discuss what is known in breast and prostate CSCs from their initial discoveries to the current therapeutic efforts in the field. Future challenges towards better CSC identification and isolation strategies will be key to shed light into how CSCs could accurately be targeted in combination to traditional therapies to ultimately prolong patient survival.

Non-coding RNAs as potential therapeutic targets in breast cancer

Paradigm shifting studies especially involving non-coding RNAs (ncRNAs) during last few decades have significantly changed the scientific perspectives regarding the complexity of cellular signalling pathways. Several studies have shown that the non-coding RNAs, initially ignored as transcriptional noise or products of erroneous transcription; actually regulate plethora of biological phenomena ranging from developmental processes to various diseases including cancer. Current strategies that are employed for the management of various cancers including that of breast fall short when their undesired side effects like Cancer Stem Cells (CSC) enrichment, low recurrence-free survival and development of drug resistance are taken into consideration. This review aims at exploring the potential role of ncRNAs as therapeutics in breast cancer, by providing a comprehensive understanding of their mechanism of action and function and their crucial contribution in regulating various aspects of breast cancer progression such as cell proliferation, angiogenesis, EMT, CSCs, drug resistance and metastasis. In addition, we also provide information about various strategies that can be employed or are under development to explore them as potential moieties that may be used for therapeutic intervention in breast cancer.

Mesenchymal Stem Cells, Immune Cells and Tumor Cells Crosstalk: A Sinister Triangle in the Tumor Microenvironment

Mesenchymal Stem Cells [MSCs] are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency. Many studies have demonstrated the immunomodulatory effects of MSCs on the innate and adaptive immune cells. As a result of interactions with tumor cells, microenvironment and immune-stimulating milieu, MSCs contribute to tumor progression by several mechanisms, including sustained proliferative signal in cancer stem cells [CSCs], inhibition of tumor cell apoptosis, transition to tumor-associated fibroblasts [TAFs], promotion of angiogenesis, stimulation of epithelial-mesenchymal transition [EMT], suppression of immune responses, and consequential promotion of tumor metastasis. Here, we present an overview of the latest findings on Janusfaced roles that MSCs play in the tumor microenvironment [TME], with a concise focus on innate and adaptive immune responses.

Mesenchymal stem cells: From regeneration to cancer

Mesenchymal stem cells (MSCs) are multipotent tissue stem cells that differentiate into a number of mesodermal tissue types, including osteoblasts, adipocytes, chondrocytes and myofibroblasts. MSCs were originally identified in the bone marrow (BM) of humans and other mammals, but recent studies have shown that they are multilineage progenitors in various adult organs and tissues. MSCs that localize at perivascular sites function to rapidly respond to external stimuli and coordinate with the vascular and immune systems to accomplish the wound healing process. Cancer, considered as wounds that never heal, is also accompanied by changes in MSCs that parallels the wound healing response. MSCs are now recognized as key players at distinct steps of tumorigenesis. In this review, we provide an overview of the function of MSCs in wound healing and cancer progression with the goal of providing insight into the development of novel MSC-manipulating strategies for clinical cancer treatment.

Evaluation of the Effects of Cultured Bone Marrow Mesenchymal Stem Cell Infusion on Hepatocarcinogenesis in Hepatocarcinogenic Mice With Liver Cirrhosis

OBJECTIVES

Liver transplantation remains the only curative therapy for decompensated liver cirrhosis. However, it has several limitations, and not all patients can receive liver transplants. Therefore, liver regenerative therapy without liver transplantation is considered necessary. In this study, we attempted minimally invasive liver regenerative therapy by peripheral vein infusion of bone marrow-derived mesenchymal stem cells (BMSCs) cultured from a small amount of autologous bone marrow fluid and evaluated the effects of BMSCs on hepatocarcinogenesis in a mouse model.

METHODS

C57BL/6 male mice were injected intraperitoneally with N-nitrosodiethylamine once at 2 weeks of age, followed by carbon tetrachloride twice a week from 6 weeks of age onwards, to create a mouse model of highly oncogenic liver cirrhosis. From 10 weeks of age, mouse isogenic green fluorescent protein-positive BMSCs (1.0 × 10⁶/body weight) were infused once every 2 weeks, for a total of 5 times, and the effects of frequent BMSC infusion on hepatocarcinogenesis were evaluated.

RESULTS

In the histologic evaluation, no significant differences were observed between the controls and BMSC-administered mice in terms of incidence rate, number, or average size of foci and tumors. However, significant suppression of fibrosis and liver injury was confirmed in the group that received BMSC infusions.

DISCUSSION

Considering that BMSC infusion did not promote carcinogenesis, even in the state of highly oncogenic liver cirrhosis, autologous BMSC infusion might be a safe and effective therapy for human decompensated liver cirrhosis.

Mesenchymal Stem Cells: Miraculous Healers or Dormant Killers?

Mesenchymal Stem Cells (MSCs) are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency to differentiate into mesodermal cell lineages. The use of MSCs in clinical settings began with high enthusiasm and the number of MSC-based clinical trials has been rising ever since. However; the very unique characteristics of MSCs that made them suitable to for therapeutic use, might give rise to unwanted outcomes, including tumor formation and progression. In this paper, we present a model of carcinogenesis initiated by MSCs, which chains together the tissue organization field theory, the stem cell theory, and the inflammation-cancer chain. We believe that some tissue resident stem cells could be leaked cells from bone marrow MSC pool to various injured tissue, which consequently transform and integrate in the host tissue. If the injury persists or chronic inflammation develops, as a consequence of recurring exposure to growth factors, cytokines, etc. the newly formed tissue from MSCs, which still has conserved their mesenchymal and stemness features, go through rapid population expansion, and nullify their tumor suppressor genes, and hence give rise to neoplastic cell (carcinomas, sarcomas, and carcino-sarcomas). Considering the probability of this hypothesis being true, the clinical and therapeutic use of MSCs should be with caution, and the recipients' long term follow-up seems to be insightful.

MicroRNAs and breast cancer stem cells: Potential role in breast cancer therapy

MicroRNAs (miRNAs) can control cancer and cancer stem cells (CSCs), and this topic has drawn immense attention recently. Stem cells are a tiny population of a bulk of tumor cells that have enormous potential in expansion and metastasis of the tumor. miRNA have a crucial role in the management of the function of stem cells. This role is to either promote or suppress the tumor. In this review, we investigated the function and different characteristics of CSCs and function of the miRNAs that are related to them. We also demonstrated the role and efficacy of these miRNAs in breast cancer and breast cancer stem cells (BCSC). Eventually, we revealed the metastasis, tumor formation, and their role in the apoptosis process. Also, the therapeutic potential of miRNA as an effective method for the treatment of BCSC was described. Extensive research is required to investigate the employment or suppression of these miRNAs for therapeutics approached in different cancers in the future.

Sequential modes of crosslinking tune viscoelasticity of cell-instructive hydrogels

Materials that can mimic the fibrillar architecture of native extracellular matrix (ECM) while allowing for independent regulation of viscoelastic properties may serve as ideal, artificial ECM (aECM) to regulate cell functions. Here we describe an interpenetrating network of click-functionalized alginate, crosslinked with a combination of ionic and covalent crosslinking, and fibrillar collagen type I. Varying the mode and magnitude of crosslinking enables tunable stiffness and viscoelasticity, while altering neither the hydrogel's microscale architecture nor diffusional transport of molecules with molecular weight relevant to typical nutrients. Further, appropriately timing sequential ionic and covalent crosslinking permits self-assembly of collagen into fibrillar structures within the network. Culture of human mesenchymal stem cells (MSCs) in this mechanically-tunable ECM system revealed that MSC expression of immunomodulatory markers is differentially impacted by the viscoelasticity and stiffness of the matrix. Together, these results describe and validate a novel material system for investigating how viscoelastic mechanical properties of ECM regulate cellular behavior.

Dynamism, Sensitivity, and Consequences of Mesenchymal and Stem-Like Phenotype of Cancer Cells

There are remarkable similarities in the description of cancer stem cells (CSCs) and cancer cells with mesenchymal phenotype. Both cell types are highly tumorigenic, resistant against common anticancer treatment, and thought to cause metastatic growth. Moreover, cancer cells are able to switch between CSC and non-CSC phenotypes and vice versa, to ensure the necessary balance within the tumor. Likewise, cancer cells can switch between epithelial and mesenchymal phenotypes via well-described transition (EMT/MET) that is thought to be crucial for tumor propagation. In this review, we discuss whether, and to which extend, the CSCs and mesenchymal cancer cells are overlapping phenomena in terms of mechanisms, origin, and implication for cancer treatment. As well, we describe the dynamism of both phenotypes and involvement of the tumor microenvironment in CSC reversion and in EMT.

Exosomes Regulate the Transformation of Cancer Cells in Cancer Stem Cell Homeostasis

In different biological model systems, exosomes are considered mediators of cell-cell communication between different cell populations. Exosomes, as extracellular vesicles, participate in physiological and pathological processes by transmitting signaling molecules such as proteins, nucleic acids, and lipids. The tumor's microenvironment consists of many types of cells, including cancer stem cells and mesenchymal cells. It is well known that these cells communicate with each other and thereby regulate the progression of the tumor. Recent studies have provided evidence that exosomes mediate the interactions between different types of cells in the tumor microenvironment, providing further insight into how these cells interact through exosome signaling. Cancer stem cells are a small kind of heterogeneous cells that existed in tumor tissues or cancer cell lines. These cells possess a stemness phenotype with a self-renewal ability and multipotential differentiation which was considered the reason for the failure of conventional cancer therapies and tumor recurrence. However, a highly dynamic equilibrium was found between cancer stem cells and cancer cells, and this indicates that cancer stem cells are no more special target and blocking the transformation of cancer stem cells and cancer cells seem to be a more significant therapy strategy. Whether exosomes, as an information transforming carrier between cells, regulated cancer cell transformation in cancer stem cell dynamic equilibrium and targeting exosome signaling attenuated the formation of cancer stem cells and finally cure cancers is worthy of further study.

Cancer stem cells and tumorigenesis

Cancer is one of the most serious diseases all over the world, and the cancer stem cell (CSC) model accounts for tumor initiation, metastasis, drug resistance, and relapse. The CSCs within tumor bulk have the capacity to self-renew, differentiate, and give rise to a new tumor. The self-renewal of CSCs is precisely regulated by various modulators, including Wnt/β-catenin signaling, Notch signaling, Hedgehog signaling, transcription factors, chromatin remodeling complexes, and non-coding RNAs. CSCs reside in their niches that are also involved in the self-renewal maintenance of CSCs and protection of CSCs from chemotherapy, radiotherapy, and even endogenous damages. Moreover, CSCs can also remodel their niches to initiate tumorigenesis. The mutual interactions between CSCs and their niches play a critical role in the regulation of CSC self-renewal and tumorigenesis as well. Many surface markers of CSCs have been identified, and these markers become first choices for CSC targeting. Due to heterogeneity and plasticity, targeting CSCs is still a big challenge for tumor elimination. In this review, we summarize recent progresses on the biological features of CSCs and targeting strategies against CSCs.

Metastatic niche functions and therapeutic opportunities

Metastasis is an inefficient process, especially during colonization at a distant organ. This bottleneck underlies the importance of the metastatic niche for seeding and outgrowth of metastases. Here, we classify the common functions of different metastatic niches: anchorage, survival support, protection from external insults, licensing proliferation and outgrowth. We highlight the emerging role of the metastatic niche in maintaining cancer stemness and promoting immune evasion, and discuss therapeutic opportunities against the metastatic niche.

Isolation and biological characteristics of multipotent mesenchymal stromal cells derived from chick embryo intestine

1. Over the past decade, rapid advancement in isolation methods for identifying markers of the once elusive intestinal stem cell (ISC) populations has laid the foundation for unravelling their complex interrelationships during homeostasis. Study on ISC in avian intestinal tissue might play a pivotal foundation for further studies on the epithelial-to-mesenchymal transition (EMT) in gastrointestinal disease and cell-based therapy as well as intestinal tissue engineering. 2. The following experiment isolated a population of fibroblast-like, plastic adhering cells derived from chick embryo intestine, showing a strong self-renewing and proliferative ability, which was maintained in vitro up to passage 25. The findings included growth characteristics, detected expression of cell surface markers and characterised the capability of these cells to differentiate towards the osteogenic, adipogenic, and chondrogenic cell lineages. 3. RT-PCR analysis showed that these cells from chick embryos expressed mesenchymal stromal cell markers CD44, CD90 and VIMENTIN as well as ISC-specific genes LGR5, MI1, SMOC2, BMI1, and HOPX. Immunofluorescence and flow cytometry confirmed this biology characterisation further. 4. In conclusion, cells were isolated from the intestine of 18-day-old chicken embryos that exhibited the biological characteristics of mesenchymal stromal cells as well as markers of intestinal stem cells. Our findings may provide a novel insight for in vitro cell culture and characteristics of ISCs in avian species, which may also indicate a benefit for obtaining cell source for intestinal tissue engineering as well as cell-based investigation for gastrointestinal disease and treatment.

Bone marrow-derived CXCR4-overexpressing MSCs display increased homing to intestine and ameliorate colitis-associated tumorigenesis in mice

Background and Objective

Increasing interest has developed in the therapeutic potential of bone marrow-derived mesenchymal stem cells (MSCs) for the treatment of inflammatory bowel disease (IBD) and IBD-induced cancer. However, whether MSCs have the ability to suppress or promote tumor development remains controversial. The stromal cell-derived factor 1 (SDF-1)/C-X-C chemokine receptor type 4 (CXCR4) axis is well known to play a critical role in the homing of MSCs. In this study, we aimed to evaluate the role of CXCR4-overexpressing MSCs on the tumorigenesis of IBD.

Methods

MSCs were transduced with lentiviral vector carrying either CXCR4 or green fluorescent protein (GFP). Chemotaxis and invasion assays were used to detect CXCR4 expression. A mouse model of colitis-associated tumorigenesis was established using azoxymethane and dextran sulfate sodium (DSS). The mice were divided into three groups and then injected with phosphate buffer saline (PBS), MSC-GFP or MSC-CXCR4.

Results

Compared with the mice injected with MSC-GFP, the mice injected with MSC-CXCR4 showed relieved weight loss, longer colons, lower tumor numbers and decreased tumor load; expression of pro-inflammatory cytokines decreased, and signal transducer and activator of transcription 3 (STAT3) phosphorylation level in colon tissue was down-regulated.

Conclusion

CXCR4-overexpressing MSCs exhibited effective anti-tumor function, which may be associated with enhanced homing to inflamed intestinal tissues.

The forkhead domain hinge-loop plays a pivotal role in DNA binding and transcriptional activity of FOXP2

Forkhead box (FOX) proteins are a ubiquitously expressed family of transcription factors that regulate the development and differentiation of a wide range of tissues in animals. The FOXP subfamily members are the only known FOX proteins capable of forming domain-swapped forkhead domain (FHD) dimers. This is proposed to be due to an evolutionary mutation (P539A) that lies in the FHD hinge loop, a key region thought to fine-tune DNA sequence specificity in the FOX transcription factors. Considering the importance of the hinge loop in both the dimerisation mechanism of the FOXP FHD and its role in tuning DNA binding, a detailed investigation into the implications of mutations within this region could provide important insight into the evolution of the FOX family. Isothermal titration calorimetry and hydrogen exchange mass spectroscopy were used to study the thermodynamic binding signature and changes in backbone dynamics of FOXP2 FHD DNA binding. Dual luciferase reporter assays were performed to study the effect that the hinge-loop mutation has on FOXP2 transcriptional activity in vivo. We demonstrate that the change in dynamics of the hinge-loop region of FOXP2 alters the energetics and mechanism of DNA binding highlighting the critical role of hinge loop mutations in regulating DNA binding characteristics of the FOX proteins.

Mammary Stem Cells and Breast Cancer Stem Cells: Molecular Connections and Clinical Implications

Cancer arises from subpopulations of transformed cells with high tumor initiation and repopulation ability, known as cancer stem cells (CSCs), which share many similarities with their normal counterparts. In the mammary gland, several studies have shown common molecular regulators between adult mammary stem cells (MaSCs) and breast cancer stem cells (bCSCs). Cell plasticity and self-renewal are essential abilities for MaSCs to maintain tissue homeostasis and regenerate the gland after pregnancy. Intriguingly, these properties are similarly executed in breast cancer stem cells to drive tumor initiation, tumor heterogeneity and recurrence after chemotherapy. In addition, both stem cell phenotypes are strongly influenced by external signals from the microenvironment, immune cells and supportive specific niches. This review focuses on the intrinsic and extrinsic connections of MaSC and bCSCs with clinical implications for breast cancer progression and their possible therapeutic applications.

The multifaceted role of exosomes in cancer progression: diagnostic and therapeutic implications [corrected]

BACKGROUND

Recent advances in cancer biology have highlighted the relevance of exosomes and nanovesicles as carriers of genetic and biological messages between cancer cells and their immediate and/or distant environments. It has been found that these molecular cues may play significant roles in cancer progression and metastasis. Cancer cells secrete exosomes containing diverse molecules that can be transferred to recipient cells and/or vice versa to induce a plethora of biological processes, including angiogenesis, metastasis formation, therapeutic resistance, epithelial-mesenchymal transition and epigenetic/stemness (re)programming. While exosomes interact with cells within the tumour microenvironment to promote tumour growth, these vesicles can also facilitate the process of distant metastasis by mediating the formation of pre-metastatic niches. Next to their tumour promoting effects, exosomes have been found to serve as potential tools for cancer diagnosis and therapy. The ease of isolating exosomes and their content from different body fluids has led to the identification of diagnostic and prognostic biomarker signatures, as well as to predictive biomarker signatures for therapeutic responses. Exosomes can also be used as cargos to deliver therapeutic anti-cancer drugs, and they can be engineered to serve as vaccines for immunotherapy. Additionally, it has been found that inhibition of exosome secretion, and thus the transfer of oncogenic molecules, holds promise for inhibiting tumour growth. Here we provide recent information on the diverse roles of exosomes in various cellular and systemic processes governing cancer progression, and discuss novel strategies to halt this progression using exosome-based targeted therapies and methods to inhibit exosome secretion and the transfer of pro-tumorigenic molecules.

CONCLUSIONS

This review highlights the important role of exosomes in cancer progression and its implications for (non-invasive) diagnostics and the development of novel therapeutic strategies, as well as its current and future applications in clinical trials.

MiR-34a Regulates Axonal Growth of Dorsal Root Ganglia Neurons by Targeting FOXP2 and VAT1 in Postnatal and Adult Mouse

Hyperglycemia impairs nerve fibers of dorsal root ganglia (DRG) neurons, leading to diabetic peripheral neuropathy (DPN). However, the molecular mechanisms underlying DPN are not fully understood. Using a mouse model of type II diabetes (db/db mouse), we found that microRNA-34a (miR-34a) was over-expressed in DRG, sciatic nerve, and foot pad tissues of db/db mice. In vitro, high glucose significantly upregulated miR-34a in postnatal and adult DRG neurons, which was associated with inhibition of axonal growth. Overexpression and attenuation of miR-34a in postnatal and adult DRG neurons suppressed and promoted, respectively, axonal growth. Bioinformatic analysis suggested that miR-34a putatively targets forkhead box protein P2 (FOXP2) and vesicle amine transport 1 (VAT1), which were decreased in diabetic tissues and in cultured DRG neurons under high glucose conditions. Dual-luciferase assay showed that miR-34a downregulated FOXP2 and VAT1 expression by targeting their 3' UTR. Gain-of- and loss-of-function analysis showed an inverse relation between augmentation of miR-34a and reduction of FOXP2 and VAT1 proteins in postnatal and adult DRG neurons. Knockdown of FOXP2 and VAT1 reduced axonal growth. Together, these findings suggest that miR-34a and its target genes of FOXP2 and VAT1 are involved in DRG neuron damage under hyperglycemia.

Downregulation of FOXP2 promotes breast cancer migration and invasion through TGFβ/SMAD signaling pathway

Cancer metastasis and relapse are the primary cause of mortality for patients with breast cancer. The present study performed quantitative proteomic analysis on the differentially expressed proteins between highly metastatic breast cancer cells and parental cells. It was revealed that forkhead box P2 (FOXP2), a transcription factor in neural development, may become a potential inhibitor of breast cancer metastasis. The results demonstrated that patients with a lower level of FOXP2 expression had significantly poorer relapse-free survival (P=0.0047). The transcription of FOXP2 was also significantly downregulated in breast cancer tissue compared with normal breast tissue (P=0.0005). In addition, FOXP2 may inhibit breast cancer cell migration and invasion in vitro. It was also revealed that the underlying mechanism may include the epithelial-mesenchymal transition process driven by the tumor growth factor β/SMAD signaling pathway. In conclusion, the present study identified FOXP2 as a novel suppressor and prognostic marker of breast cancer metastasis. These results may provide further insight into breast cancer prevention and the development of novel treatments.

Expression Differentiation Is Not Helpful in Identifying Prognostic Genes Based on TCGA Datasets

A routine pipeline seems very common in many cancer studies that expression differentiation might be helpful in identifying prognostic molecules. There also exists a striking unanimity that molecules upregulated in cancer usually shorten survival, while downregulated ones have the opposite effect. In this study, based on the transcriptional profiles of 18 malignancies, cancer and corresponding adjacent normal tissues were used to calculate differential scores. Cox correlation coefficients of global genes were also calculated to denote survival association. The relationship between expression differentiation and survival association has been extensively studied in 18 malignancy types. Contradictory to our stereotypic research pattern, expression differentiation between cancer and adjacent normal tissues was proven irrelevant to corresponding survival correlation. Surprisingly, the more stringent cutoff we used in differentially expressed gene identification, the less prognostic information we would obtain from the collected gene groups. Moreover, the direction of dysregulated genes in cancer was irrelevant to the direction of corresponding survival correlation. Cancer-normal expression differentiation is irrelevant to genes’ survival correlation in multiple cancers and, therefore, not helpful in identifying prognostic genes. For future studies, it is more sensible to look into another alternative rather than collect differentially expressed molecules in the initial step.

Cancer stem cells as key drivers of tumour progression

BACKGROUND

Cancer stem cells (CSCs) are subpopulations of cancer cells sharing similar characteristics as normal stem or progenitor cells such as self-renewal ability and multi-lineage differentiation to drive tumour growth and heterogeneity. Throughout the cancer progression, CSC can further be induced from differentiated cancer cells via the adaptation and cross-talks with the tumour microenvironment as well as a response from therapeutic pressures, therefore contributes to their heterogeneous phenotypes. Challengingly, conventional cancer treatments target the bulk of the tumour and are unable to target CSCs due to their highly resistance nature, leading to metastasis and tumour recurrence.

MAIN BODY

This review highlights the roles of CSCs in tumour initiation, progression and metastasis with a focus on the cellular and molecular regulators that influence their phenotypical changes and behaviours in the different stages of cancer progression. We delineate the cross-talks between CSCs with the tumour microenvironment that support their intrinsic properties including survival, stemness, quiescence and their cellular and molecular adaptation in response to therapeutic pressure. An insight into the distinct roles of CSCs in promoting angiogenesis and metastasis has been captured based on in vitro and in vivo evidences.

CONCLUSION

Given dynamic cellular events along the cancer progression and contributions of resistance nature by CSCs, understanding their molecular and cellular regulatory mechanism in a heterogeneous nature, provides significant cornerstone for the development of CSC-specific therapeutics.

Inflammatory Human Umbilical Cord-Derived Mesenchymal Stem Cells Promote Stem Cell-Like Characteristics of Cancer Cells in an IL-1β-Dependent Manner

To ensure the safety of clinical applications of MSCs, thorough understanding of their impacts on tumor initiation and progression is essential. Here, to further explore the complex dialog between MSCs and tumor cells, umbilical cord-derived mesenchymal stem cells (UC-MSCs) were employed to be cocultured with either breast or ovarian cancer cells. Though having no obvious influence on proliferation or apoptosis, UC-MSCs exerted intense stem cell-like properties promoting effects on both cancer models. Cocultured cancer cells showed enriched side population, enhanced sphere formation ability, and upregulated pluripotency-associated stem cell markers. Human cytokine array and real-time PCR revealed a panel of MSC-derived prostemness cytokines CCL2, CXCL1, IL-8, and IL-6 which were induced upon coculturing. We further revealed IL-1β, a well-characterized proinflammatory cytokine, to be the inducer of these prostemness cytokines, which was generated from inflammatory UC-MSCs in an autocrine manner. Additionally, with introduction of IL-1RA (an IL-1 receptor antagonist) into the coculturing system, the stem cell-like characteristics promoting effects of inflammatory UC-MSCs were partially blocked. Taken together, these findings suggest that transduced inflammatory MSCs work as a major source of IL-1β in tumor microenvironment and initiate the formation of prostemness niche via regulating their secretome in an IL-1β-dependent manner.

FOXP2-positive diffuse large B-cell lymphomas exhibit a poor response to R-CHOP therapy and distinct biological signatures

FOXP2 shares partially overlapping normal tissue expression and functionality with FOXP1; an established diffuse large B-cell lymphoma (DLBCL) oncogene and marker of poor prognosis. FOXP2 is expressed in the plasma cell malignancy multiple myeloma but has not been studied in DLBCL, where a poor prognosis activated B-cell (ABC)-like subtype display partially blocked plasma cell differentiation. FOXP2 protein expression was detected in ABC-DLBCL cell lines, and in primary DLBCL samples tumoral FOXP2 protein expression was detected in both germinal center B-cell-like (GCB) and non-GCB DLBCL. In biopsies from DLBCL patients treated with immunochemotherapy (R-CHOP), ≥ 20% nuclear tumoral FOXP2-positivity (n = 24/158) correlated with significantly inferior overall survival (OS: P = 0.0017) and progression-free survival (PFS: P = 0.0096). This remained significant in multivariate analysis against either the international prognostic index score or the non-GCB DLBCL phenotype (P < 0.05 for both OS and PFS). Expression of BLIMP1, a marker of plasmacytic differentiation that is commonly inactivated in ABC-DLBCL, did not correlate with patient outcome or FOXP2 expression in this series. Increased frequency of FOXP2 expression significantly correlated with FOXP1-positivity (P = 0.0187), and FOXP1 co-immunoprecipitated FOXP2 from ABC-DLBCL cells indicating that these proteins can co-localize in a multi-protein complex. FOXP2-positive DLBCL had reduced expression of HIP1R (P = 0.0348), which is directly repressed by FOXP1, and exhibited distinct patterns of gene expression. Specifically in ABC-DLBCL these were associated with lower expression of immune response and T-cell receptor signaling pathways. Further studies are warranted to investigate the potential functional cooperativity between FOXP1 and FOXP2 in repressing immune responses during the pathogenesis of high-risk DLBCL.

The Role of micro RNAs in Breast Cancer Metastasis: Preclinical Validation and Potential Therapeutic Targets

Despite the approval of several molecular therapies in the last years, breast cancer-associated death ranks as the second highest in women. This is due to metastatic disease, which represents a challenge for treatment. A better understanding of the molecular mechanisms of metastasis is, therefore, of paramount importance. In this review we summarize the role of micro RNAs (miRs) involved in metastasis of breast cancer. We present an overview on metastasis-promoting, -suppressing and context-dependent miRs with both activities. We have categorized the corresponding miRs according to their target classes, interaction with stromal cells or exosomes. The pathways affected by individual miRs are outlined in regard to in vitro properties, activity in metastasis-related in vivo models and clinical significance. Current approaches that may be suitable for therapeutic inhibition or restauration of miR activity are outlined. Finally, we discuss the delivery bottlenecks which present as a major challenge in nucleic acid (miR)-based therapies.

The untold stories of the speech gene, the FOXP2 cancer gene

FOXP2 encodes a transcription factor involved in speech and language acquisition. Growing evidence now suggests that dysregulated FOXP2 activity may also be instrumental in human oncogenesis, along the lines of other cardinal developmental transcription factors such as DLX5 and DLX6 [1-4]. Several FOXP familymembers are directly involved during cancer initiation, maintenance and progression in the adult [5-8]. This may comprise either a pro-oncogenic activity or a deficient tumor-suppressor role, depending upon cell types and associated signaling pathways. While FOXP2 is expressed in numerous cell types, its expression has been found to be down-regulated in breast cancer [9], hepatocellular carcinoma [8] and gastric cancer biopsies [10]. Conversely, overexpressed FOXP2 has been reported in multiple myelomas, MGUS (Monoclonal Gammopathy of Undetermined Significance), several subtypes of lymphomas [5,11], as well as in neuroblastomas [12] and ERG fusion-negative prostate cancers [13]. According to functional evidences reported in breast cancer [9] and survey of recent transcriptomic and proteomic analyses of different tumor biopsies, we postulate that FOXP2 dysregulation may play a main role throughout cancer initiation and progression. In some cancer conditions, FOXP2 levels are now considered as a critical diagnostic marker of neoplastic cells, and in many situations, they even bear strong prognostic value [5]. Whether FOXP2 may further become a therapeutic target is an actively explored lead. Knowledge reviewed here may help improve our understanding of FOXP2 roles during oncogenesis and provide cues for diagnostic, prognostic and therapeutic analyses.