MicroRNA-143 targets CD44 to inhibit breast cancer progression and stem cell-like properties

Extracellular matrix marker LAMC2 targets ZEB1 to promote TNBC malignancy via up-regulating CD44/STAT3 signaling pathway

BACKGROUND

Triple negative breast cancer (TNBC) is a heterogeneous and aggressive disease characterized by a high risk of mortality and poor prognosis. It has been reported that Laminin γ2 (LAMC2) is highly expressed in a variety of tumors, and its high expression is correlated with cancer development and progression. However, the function and mechanism by which LAMC2 influences TNBC remain unclear.

METHODS

Kaplan-Meier survival analysis and Immunohistochemical (IHC) staining were used to examine the expression level of LAMC2 in TNBC. Subsequently, cell viability assay, wound healing and transwell assay were performed to detect the function of LAMC2 in cell proliferation and migration. A xenograft mouse model was used to assess tumorigenic function of LAMC2 in vivo. Luciferase reporter assay and western blot were performed to unravel the underlying mechanism.

RESULTS

In this study, we found that higher expression of LAMC2 significantly correlated with poor survival in the TNBC cohort. Functional characterization showed that LAMC2 promoted cell proliferation and migration capacity of TNBC cell lines via up-regulating CD44. Moreover, LAMC2 exerted oncogenic roles in TNBC through modulating the expression of epithelial-mesenchymal transition (EMT) markers. Luciferase reporter assay verified that LAMC2 targeted ZEB1 to promote its transcription. Interestingly, LAMC2 regulated cell migration in TNBC via STAT3 signaling pathway.

CONCLUSION

LAMC2 targeted ZEB1 via activating CD44/STAT3 signaling pathway to promote TNBC proliferation and migration, suggesting that LAMC2 could be a potential therapeutic target in TNBC patients.

Cooperatively inhibition effect of miR-143-5p and miR-145-5p in tumorigenesis of glioblastoma cells through modulating AKT signaling pathway

Introduction

As the most common aggressive primary brain tumor, glioblastoma is inevitably a recurrent malignancy whose patients' prognosis is poor. miR-143 and miR-145, as tumor suppressor miRNAs, are downregulated through tumorigenesis of multiple human cancers, including glioblastoma. These two miRNAs regulate numerous cellular processes, such as proliferation and migration. This research was intended to explore the simultaneous replacement effect of miR-143, and miR-145 on in vitro tumorgenicity of U87 glioblastoma cells.

Methods

U87 cells were cultured, and transfected with miR-143-5p and miR-145-5p. Afterward, the changes in cell viability, and apoptosis induction were determined by MTT assay and Annexin V/PI staining. The accumulation of cells at the cell cycle phases was assessed using the flow cytometry. Wound healing and colony formation assays were performed to study cell migration. qRT-PCR and western blot techniques were utilized to quantify gene expression levels.

Results

Our results showed that miR-143-5p and 145-5p exogenous upregulation cooperatively diminished cell viability, and enhanced U-87 cell apoptosis by modulating Caspase-3/8/9, Bax, and Bcl-2 protein expression. The combination therapy increased accumulation of cells at the sub-G1 phase by modulating CDK1, Cyclin D1, and P53 protein expression. miR-143/145-5p significantly decreased cell migration, and reduced colony formation ability by the downregulation of c-Myc and CD44 gene expression. Furthermore, the results showed the combination therapy of these miRNAs could remarkably downregulate phosphorylated-AKT expression levels.

Conclusion

In conclusion, miR-143 and miR-145 were indicated to show cooperative anti- cancer effects on glioblastoma cells via modulating AKT signaling as a new therapeutic approach.

MicroRNA-143 as a potential tumor suppressor in cancer: An insight into molecular targets and signaling pathways

MicroRNAs (MiRNAs), which are highly conserved and small noncoding RNAs, negatively regulate gene expression and influence signaling pathways involved in essential biological activities, including cell proliferation, differentiation, apoptosis, and cell invasion. MiRNAs have received much attention in the past decade due to their significant roles in cancer development. In particular, microRNA-143 (miR-143) is recognized as a tumor suppressor and is downregulated in most cancers. However, it seems that miR-143 is upregulated in rare cases, such as prostate cancer stem cells, and acts as an oncogene. The present review will outline the current studies illustrating the impact of miR-143 expression levels on cancer progression and discuss its target genes and their relevant signaling pathways to discover a potential therapeutic way for cancer.

L1CAM promotes vasculogenic mimicry formation by miR-143-3p-induced expression of hexokinase 2 in glioma

In recent decades, antiangiogenic therapy, which blocks the supply of oxygen and nutrition to tumor cells, has become a promising clinical strategy for the treatment of patients with tumors. However, recent studies revealed that vasculogenic mimicry (VM), which is the process by which vascular morphological structures are formed by highly invasive tumor cells, has been considered a potential factor for the failure of antiangiogenic therapy in patients with tumors. Thus, inhibition of VM formation might be a potential target for improving the outcome of antiangiogenic strategies. However, the mechanism underlying VM formation is still incompletely elucidated. Herein, we report that L1CAM might be a critical regulator of VM formation in glioma, and might be associated with the resistance of glioma to antiangiogenic therapy. We found that the tumor-invasion and tube-formation capabilities of L1CAM-overexpressing cells were significantly enhanced in vitro and in vivo. In addition, the results indicated that miR-143-3p, which might directly target the 3'UTR of the hexokinase 2 (HK2) gene to regulate its protein expression, was subsequently involved in L1CAM-mediated VM formation by glioma cells. Further study revealed that the regulation of MMP2, MMP9, and VEGFA expression was involved in this process. Moreover, we identified that activation of the downstream PI3K/AKT signaling pathway of the L1CAM/HK2 cascade is critical for VM formation by glioma cells. Furthermore, we found that the combined treatment of anti-L1CAM neutralizing monoclonal antibody and bevacizumab increases efficacy beyond that of bevacizumab alone, and suppresses glioma growth in vivo, indicating that the inhibition of L1CAM-mediated VM formation might efficiently improve the effect of antiangiogenic treatment for glioma patients. Together, our findings demonstrated a critical role of L1CAM in regulating VM formation in glioma, and that L1CAM might be a potential target for ameliorating tumor resistance to antiangiogenic therapy in glioma patients.

Negative regulation of CD44st by miR-138-5p affects the invasive ability of breast cancer cells and patient prognosis after breast cancer surgery

OBJECTIVE

To investigate how the negative regulation of CD44st by miR-138-5p affects the invasive ability of breast cancer cell lines and prognosis in postoperative breast cancer patients.

METHODS

RT-PCR, qRT-PCR, and western blot assays were used to detect the expression of CD44s, CD44v6, and CD44st at both mRNA and protein levels. The expression of miR-138-5p in breast cancer cell lines was also evaluated. The binding ability of miR-138-5p to CD44st was determined via a dual-luciferase assay. The CD44 protein expression in breast cancer tissues was detected using immunohistochemistry. A Transwell assay was used to detect the invasive ability of tumor cells. The correlation between CD44st and miR-138-5p mRNA expression in breast cancer tissues was evaluated using qRT-PCR, and the relationship between clinicopathological features was statistically analyzed.

RESULTS

CD44s and CD44v6 were highly expressed in MDAMB-231 cell line, while CD44st was highly expressed in MCF-7/Adr and Skbr-3 cells. None of the CD44 isoforms were expressed in MCF-7 cells. The miR-138-5p was highly expressed in MCF-7 cells, but not in MCF-7/Adr, Skbr-3, and MDAMB-231 cells. The dual-luciferase assay suggested that miR-138-5p could bind to wild-type CD44st 3'-UTR, miR-138-5p overexpression significantly inhibited the expression level of CD44 protein in MCF-7/Adr cells, and miR-138-5p + CD44st (3'-UTR)-treated MCF-7/Adr and Skbr-3 cells were significantly less invasive than those in the control group (P < 0.05). RT-PCR results for 80 postoperative breast cancer patients showed that the mRNA expression rate for CD44st was higher in cancer tissues than in paracancerous tissues, and the expression rate of miR-138-5p was higher in paracancerous tissues than in cancerous tissues (P < 0.01). In cancer tissues, CD44st was negatively correlated with miR-138-5p expression, with correlation coefficient r = -0.76 (Pearson's correlation), coefficient of determination R2 = 0.573, F = 106.89, and P < 0.001. The median overall survival value for patients in the low miR-138-5p expression group was 40.39 months [95% confidence interval (CI): 35.59-45.18 months] and 56.30 months (95% CI: 54.38-58.21 months) for patients in the high-expression group, with a log rank (Mantel-Cox) of 13.120, one degree of freedom, and P < 0.001.

CONCLUSION

In breast cancer cell lines, miR-138-5p negatively regulated expression of CD44st and affected the invasive ability of tumor cells and patient prognosis after breast cancer surgery.

Biological and molecular studies on specific immune cells treated with checkpoint inhibitors for the thera-personal approach of breast cancer patients (ex-vivo study)

Immunotherapy becomes a promising line of treatment for breast cancer (BC) however, its success rate is still limited.

Methods

The study was designed to optimize the condition for producing an effective dendritic cell (DCs) based immunotherapy by using DCs and T lymphocytes together with tumor-infiltrating lymphocytes (TILs) and tumor-infiltrating DCs (TIDCs), treated with anti-PD1 and anti-CTLA4 monoclonal antibodies. This mixture of immune cells was co-cultured with autologous breast cancer cells (BCCs) isolated from 26 BC females.

Results

There was a significant upregulation of CD86 and CD83 on DCs (p = 0.001 and 0.017, respectively), similarly upregulation of CD8, CD4 and CD103 on T cells (p = 0.031, 0.027, and 0.011, respectively). While there was a significant downregulation of FOXP3 and combined CD25.CD8 expression on regulatory T cells (p = 0.014 for both). Increased CD8/Foxp3 ratio (p < 0.001) was also observed. CD133, CD34 and CD44 were downregulated on BCCs (p = 0.01, 0.021, and 0.015, respectively). There was a significant increase in interferon-γ (IFN-γ, p < 0.001), lactate dehydrogenase (LDH, p = 0.02), and a significant decrease in vascular endothelial growth factor (VEGF, p < 0.001) protein levels. Gene expression of FOXP3 and Programmed cell death ligand 1 (PDL-1) were downregulated in BCCs (p < 0.001, for both), similarly cytotoxic T lymphocyte antigen-4 (CTLA4, p = 0.02), Programmed cell death 1 (PD-1, p < 0.001) and FOXP3 (p < 0.001) were significantly downregulated in T cells.

Conclusion

Ex-vivo activation of immune cells (DCs, T cells, TIDCs, and TILs) with immune checkpoint inhibitors could produce a potent and effective BC immunotherapy. However, these data should be validated on an experimental animal model to be transferred to the clinical setting.

A promising antitumor method: Targeting CSC with immune cells modified with CAR

Tumors pose a great threat to human health; as a subgroup of tumor cells, cancer stem cells (CSCs) contribute to the genesis, development, metastasis, and recurrence of tumors because of their enhanced proliferation and multidirectional differentiation. Thus, a critical step in tumor treatment is to inhibit CSCs. Researchers have proposed many methods to inhibit or reduce CSCs, including monoclonal antibodies targeting specific surface molecules of CSCs, signal pathway inhibitors, and energy metabolic enzyme inhibitors and inducing differentiation therapy. Additionally, immunotherapy with immune cells engineered with a chimeric antigen receptor (CAR) showed favorable results. However, there are few comprehensive reviews in this area. In this review, we summarize the recent CSC targets used for CSC inhibition and the different immune effector cells (T cells, natural killer (NK) cells, and macrophages) which are engineered with CAR used for CSC therapy. Finally, we list the main challenges and options in targeting CSC with CAR-based immunotherapy. The design targeting two tumor antigens (one CSC antigen and one mature common tumor antigen) should be more reasonable and practical; meanwhile, we highlight the potential of CAR-NK in tumor treatment.

Emerging Therapeutic Agents for Colorectal Cancer

There are promising new therapeutic agents for CRC patients, including novel small-molecule inhibitors and immune checkpoint blockers. We focused on emerging CRC’s therapeutic agents that have shown the potential for progress in clinical practice. This review provides an overview of tyrosine kinase inhibitors targeting VEGF and KIT, BRAF and MEK inhibitors, TLR9 agonist, STAT3 inhibitors, and immune checkpoint blockers (PD1/PDL-1 inhibitors), for which recent advances have been reported. These new agents have the potential to provide benefits to CRC patients with unmet medical needs.

CD44: A Multifunctional Mediator of Cancer Progression

CD44, a non-kinase cell surface transmembrane glycoprotein, has been widely implicated as a cancer stem cell (CSC) marker in several cancers. Cells overexpressing CD44 possess several CSC traits, such as self-renewal and epithelial-mesenchymal transition (EMT) capability, as well as a resistance to chemo- and radiotherapy. The CD44 gene regularly undergoes alternative splicing, resulting in the standard (CD44s) and variant (CD44v) isoforms. The interaction of such isoforms with ligands, particularly hyaluronic acid (HA), osteopontin (OPN) and matrix metalloproteinases (MMPs), drive numerous cancer-associated signalling. However, there are contradictory results regarding whether high or low CD44 expression is associated with worsening clinicopathological features, such as a higher tumour histological grade, advanced tumour stage and poorer survival rates. Nonetheless, high CD44 expression significantly contributes to enhanced tumourigenic mechanisms, such as cell proliferation, metastasis, invasion, migration and stemness; hence, CD44 is an important clinical target. This review summarises current research regarding the different CD44 isoform structures and their roles and functions in supporting tumourigenesis and discusses CD44 expression regulation, CD44-signalling pathways and interactions involved in cancer development. The clinical significance and prognostic value of CD44 and the potential of CD44 as a therapeutic target in cancer are also addressed.

Maternal cecal microbiota transfer rescues early-life antibiotic-induced enhancement of type 1 diabetes in mice

Early-life antibiotic exposure perturbs the intestinal microbiota and accelerates type 1 diabetes (T1D) development in the NOD mouse model. Here, we found that maternal cecal microbiota transfer (CMT) to NOD mice after early-life antibiotic perturbation largely rescued the induced T1D enhancement. Restoration of the intestinal microbiome was significant and persistent, remediating the antibiotic-depleted diversity, relative abundance of particular taxa, and metabolic pathways. CMT also protected against perturbed metabolites and normalized innate and adaptive immune effectors. CMT restored major patterns of ileal microRNA and histone regulation of gene expression. Further experiments suggest a gut-microbiota-regulated T1D protection mechanism centered on Reg3γ, in an innate intestinal immune network involving CD44, TLR2, and Reg3γ. This regulation affects downstream immunological tone, which may lead to protection against tissue-specific T1D injury.

Gold Nanoparticles; Potential Nanotheranostic Agent in Breast Cancer: A Comprehensive Review with Systematic Search Strategy

BACKGROUND

Breast cancer is a heterogeneous disease typically prevalent among women and is the second-largest cause of death worldwide. Early diagnosis is the key to minimize the cancer-induced complication, however, the conventional diagnostic strategies have been sluggish, complex, and, to some extent, non-specific. Therapeutic tools are not so convenient and side effects of current therapies offer the development of novel theranostic tool to combat this deadly disease.

OBJECTIVE

This article aims to summarize the advances in the diagnosis and treatment of breast cancer with gold nanoparticles (GNP or AuNP).

METHODS

A systematic search was conducted in the three popular electronic online databases including PubMed, Google Scholar, and Web of Science, regarding GNP as breast cancer theranostics.

RESULTS

Published literature demonstrated that GNPs tuned with photosensitive moieties, nanomaterials, drugs, peptides, nucleotide, peptides, antibodies, aptamer, and other biomolecules improve the conventional diagnostic and therapeutic strategies of breast cancer management with minimum cytotoxic effect. GNP derived diagnosis system assures reproducibility, reliability, and accuracy cost-effectively. Additionally, surface-modified GNP displayed theranostic potential even in the metastatic stage of breast cancer.

CONCLUSION

Divergent strategies have shown the theranostic potential of surface tuned GNPs against breast cancer even in the metastatic stage with minimum cytotoxic effects both in vitro and in vivo.

Expression Profiling of microRNA From Peripheral Blood of Dairy Cows in Response to Staphylococcus aureus-Infected Mastitis

As the main pathogen causing dairy cow mastitis, Staphylococcus aureus can cause subclinical mastitis, which is difficult to be diagnosed. It seriously affects milk quality and the economic benefits of the dairy industry. Therefore, it is very necessary to find biomarkers for early diagnosis of S. aureus-infected mastitis in peripheral blood of dairy cows. In this study, S. aureus was used to infect the mammary gland tissues of dairy cows, and a mastitis model was successfully constructed. The RNAseq technology was used to determine the expression profiles of microRNA (miRNA) from peripheral blood of dairy cows infected with S. aureus at 0, 1, 3, 5, and 7 days. A total of 288 differentially expressed miRNAs (DIE-miRNAs) were found, of which 108 were known miRNAs and 180 were novel predicted miRNAs. Bioinformatics analysis results showed that the above DIE-miRNAs might be involved in 10 immune system-related signaling pathways (i.e., chemokine signaling pathway, leukocyte transendothelial migration, natural killer cell-mediated cytotoxicity, toll-like receptor signaling pathway, Jak-STAT signaling pathway, MAPK signaling pathway, Wnt signaling pathway, cell adhesion molecules, cytokine-cytokine receptor interaction, and ECM-receptor interaction), thus regulating the process of S. aureus mastitis. It was also found that the expression variation of up-regulated expression of miR-320a, miR-19a, and miR-19b as well as down-regulated expression of miR-143, miR-205, and miR-24 reached a significant level on the 5th and 7th day of infection, suggesting that they might play an important biological role in mastitis and provide a direction for the research and development of molecular therapy technology for mastitis. However, at different times after S. aureus infection, miR-1301 was significantly up-regulated in peripheral blood. miR-2284r was significantly down-regulated, suggesting that these two miRNAs might be the new blood biomarkers for S. aureus-infected dairy cow mastitis. The above results laid a new foundation for the research and development of molecular diagnosis and biological therapy technology for S. aureus-infected mastitis in dairy cow.

CD44 polymorphisms and its variants, as an inconsistent marker in cancer investigations

Among cell surface markers, CD44 is considered the main marker for identifying and isolating the cancer stem cells (CSCs) among other cells and has attracted significant attention in a variety of research areas. Many studies have shown the essential roles of CD44 in initiation, metastasis, and tumorigenesis in different types of cancer; however, the validity of CD44 as a therapeutic or diagnostic target has not been fully confirmed in some other studies. Whereas the association of specific single nucleotide polymorphisms (SNPs) in the CD44 gene and related variants with cancer risk have been observed in clinical investigations, the significance of these findings remains controversial. Here, we aimed to provide an up-to-date overview of recent studies on the association of CD44 polymorphisms and its variants with different kinds of cancer to determine whether or not it can be used as an appropriate candidate for cancer tracking.

CD44 as a tumor biomarker and therapeutic target

CD44, a complex transmembrane glycoprotein, exists in multiple molecular forms, including the standard isoform CD44s and CD44 variant isoforms. CD44 participates in multiple physiological processes, and aberrant expression and dysregulation of CD44 contribute to tumor initiation and progression. CD44 represents a common biomarker of cancer stem cells, and promotes epithelial-mesenchymal transition. CD44 is involved in the regulation of diverse vital signaling pathways that modulate cancer proliferation, invasion, metastasis and therapy-resistance, and it is also modulated by a variety of molecules in cancer cells. In addition, CD44 can serve as an adverse prognostic marker among cancer population. The pleiotropic roles of CD44 in carcinoma potentially offering new molecular target for therapeutic intervention. Preclinical and clinical trials for evaluating the pharmacokinetics, efficacy and drug-related toxicity of CD44 monoclonal antibody have been carried out among tumors with CD44 expression. In this review, we focus on current data relevant to CD44, and outline CD44 structure, the regulation of CD44, functional properties of CD44 in carcinogenesis and cancer progression as well as the potential CD44-targeting therapy for cancer management.

MSI1 Promotes the Expression of the GBM Stem Cell Marker CD44 by Impairing miRNA-Dependent Degradation

Simple Summary

Glioblastoma (GBM) is the most lethal brain tumor with a median survival rate of approximately 14 months. GBM patients commonly suffer from tumor recurrence, indicating that populations of chemo/radio-resistant stem cell-like tumor cells survive treatments. Here we reveal that the neuronal stem cell marker Musashi1 (MSI1) is highly expressed in primary GBM and recurrences. We identify a novel regulatory role of MSI1 in GBM-derived cell lines and patient-derived tumorspheres, the enhancement of stemness marker expression, here demonstrated for CD44. Furthermore, we provide a rationale for MSI1-centered therapeutic targeting strategies to improve treatment options of this chemo/radio-resistant malignancy.

Abstract

The stem cell marker Musashi1 (MSI1) is highly expressed during neurogenesis and in glioblastoma (GBM). MSI1 promotes self-renewal and impairs differentiation in cancer and non-malignant progenitor cells. However, a comprehensive understanding of its role in promoting GBM-driving networks remains to be deciphered. We demonstrate that MSI1 is highly expressed in GBM recurrences, an oncologist’s major defiance. For the first time, we provide evidence that MSI1 promotes the expression of stem cell markers like CD44, co-expressed with MSI1 within recurrence-promoting cells at the migrating front of primary GBM samples. With GBM cell models of pediatric and adult origin, including isolated primary tumorspheres, we show that MSI1 promotes stem cell-like characteristics. Importantly, it impairs CD44 downregulation in a 3′UTR- and miRNA-dependent manner by controlling mRNA turnover. This regulation is disturbed by the previously reported MSI1 inhibitor luteolin, providing further evidence for a therapeutic target potential of MSI1 in GBM treatment.

Role of CD44 in breast cancer

Breast cancer (BC) is among the most prevalent type of malignancy affecting females worldwide. BC is classified into different types according to the status of the expression of receptors such as estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), and progesterone receptor (PR). Androgen receptor (AR) appears to be a promising therapeutic target of BC. Binding of 5α-dihydrotestosterone (DHT) to AR controls the expression of microRNA (miRNA) molecules in BC, consequently, affecting protein expression. One of these proteins is the transmembrane glycoprotein cluster of differentiation 44 (CD44). Remarkably, CD44 is a common marker of cancer stem cells in BC. It functions as a co-receptor for a broad diversity of extracellular matrix ligands. Several ligands, primarily hyaluronic acid (HA), can interact with CD44 and mediate its functions. CD44 promotes a variety of functions independently or in cooperation with other cell-surface receptors through activation of varied signaling pathways like Rho GTPases, Ras-MAPK, and PI3K/AKT pathways to regulate cell adhesion, migration, survival, invasion, and epithelial-mesenchymal transition. In this review, we present the relations between AR, miRNA, and CD44 and their roles in BC.

miRNAs in Health and Disease: A Focus on the Breast Cancer Metastatic Cascade towards the Brain

MicroRNAs (miRNAs) are small non-coding RNAs that mainly act by binding to target genes to regulate their expression. Due to the multitude of genes regulated by miRNAs they have been subject of extensive research in the past few years. This state-of-the-art review summarizes the current knowledge about miRNAs and illustrates their role as powerful regulators of physiological processes. Moreover, it highlights their aberrant expression in disease, including specific cancer types and the differential hosting-metastases preferences that influence several steps of tumorigenesis. Considering the incidence of breast cancer and that the metastatic disease is presently the major cause of death in women, emphasis is put in the role of miRNAs in breast cancer and in the regulation of the different steps of the metastatic cascade. Furthermore, we depict their involvement in the cascade of events underlying breast cancer brain metastasis formation and development. Collectively, this review shall contribute to a better understanding of the uniqueness of the biologic roles of miRNAs in these processes, to the awareness of miRNAs as new and reliable biomarkers and/or of therapeutic targets, which can change the landscape of a poor prognosis and low survival rates condition of advanced breast cancer patients.

Cell-free miRNAs as non-invasive biomarkers in breast cancer: Significance in early diagnosis and metastasis prediction

Breast cancer is one of the genetic diseases causing a high mortality among women around the world. Despite the availability of advanced diagnostic tools and treatment strategies, the incidence of breast cancer is increasing every year. This is due to the lack of accurate and reliable biomarkers whose deficiency creates difficulty in early breast cancer recognition, subtypes determination, and metastasis prophecy. Although biomarkers such as ER, PR, Her2, Ki-67, and other genetic platforms e.g. MammaPrint®, Oncotype DX®, Prosigna® or EndoPredict® are available for determination of breast cancer diagnosis and prognosis. However, pertaining to heterogeneous nature, lack of sensitivity, and specificity of these markers, it is still incessant to overcome breast cancer burden. Therefore, a novel biomarker is urgently needed for therapeutic diagnosis and improving prognosis. Lately, it has become more evident that cell-free miRNAs might be useful as good non-invasive biomarkers that are associated with different events in carcinogenesis. For example, some known biomarkers such as miR-21, miR-23a, miR-34a are associated with molecular subtyping and different biomolecular aspects i.e. apoptosis, angiogenesis, metastasis, and miR-1, miR-10b, miR-16 are associated with drug response. Cell-free miRNAs present in human body fluids have proven to be potential biomarkers with significant prognostic and predictive values. Numerous studies have found a distinct expression profile of circulating miRNAs in breast tumour versus non-tumour and in early and advanced-stage, thus implicating its clinical relevance. This review article will highlight the importance of different cell-free miRNAs as a biomarker for early breast cancer detection, subtype classification, and metastasis forecast.

Characterizing CD44 regulatory microRNAs as putative therapeutic agents in human melanoma

The multistructural and multifunctional transmembrane glycoprotein CD44 is overexpressed in many tumors of distinct origin including malignant melanoma and contributes to a poor prognosis by affecting cell proliferation, cell migration, and also the sensitivity for apoptosis induction. Previous studies reported so far 15 CD44 regulatory microRNAs (miRs) in different cell systems. Using a novel method for miR affinity purification miR-143-3p was identified as most potent binder to the 3' untranslated region (UTR) of CD44. Overexpression of miR-143-3p in melanoma cells inhibits CD44 translation, which is accompanied by a reduced proliferation, migration and enhanced daunorubicin induced apoptosis of melanoma cells in vitro. Analyses of discordant CD44 and miR-143-3p expression levels in human melanocytic nevi and dermal melanoma samples demonstrated medium to high CD44 levels with no association to tumor grading or staging. The CD44 expression correlated to PD-L1, but not to MART-1 expression in malignant melanoma. Interestingly, the CD44 expression was inversely correlated to the infiltration of pro-inflammatory immune effector cells. In conclusion, the tumor suppressive miR-143-3p was identified as the most potent CD44 inhibitory miR, which affects growth characteristics of melanoma cells suggesting the implementation of miR-143-3p as as a potential anti-CD44 therapy of malignant melanoma.

Metal carcinogen exposure induces cancer stem cell-like property through epigenetic reprograming: A novel mechanism of metal carcinogenesis

Arsenic, cadmium, nickel and hexavalent chromium are among the most common environmental pollutants and potent carcinogens. Chronic exposure to these metals causes various types of cancer in humans, representing a significant environmental health issue. Although under active investigation, the mechanisms of metal carcinogenesis have not been clearly defined. One common feature of these metal carcinogens is that they are all able to cause various epigenetic dysregulations, which are believed to play important roles in their carcinogenicity. However, how metal carcinogen-caused epigenetic dysregulation contributes to metal carcinogenesis remains largely unknown. The evolution of cancer stem cell (CSC) theory has opened exciting new avenues for studying the mechanism of metal carcinogenesis. Increasing evidence indicates that chronic metal carcinogen exposure produces CSC-like cells through dysregulated epigenetic mechanisms. This review will first provide some brief introductions about CSC, epigenetics and epigenetic regulation of CSCs; then summarize progresses in recent studies on metal carcinogen-induced CSC-like property through epigenetic reprograming as a novel mechanism of metal carcinogenesis. Some perspectives for future studies in this field are also presented.

Hyaluronan-CD44 axis orchestrates cancer stem cell functions

The prominent role of CD44 in tumor cell signaling together with its establishment as a cancer stem cell (CSC) marker for various tumor entities imply a key role for CD44 in CSC functional properties. Hyaluronan, the main ligand of CD44, is a major constituent of CSC niche and, therefore, the hyaluronan-CD44 signaling axis is of functional importance in this special microenvironment. This review aims to provide recent advances in the importance of hyaluronan-CD44 interactions in the acquisition and maintenance of a CSC phenotype. Hyaluronan-CD44 axis has a substantial impact on stemness properties of CSCs and drug resistance through induction of EMT program, oxidative stress resistance, secretion of extracellular vesicles/exosomes and epigenetic control. Potential therapeutic approaches targeting CSCs based on the hyaluronan-CD44 axis are also presented.

The biology and role of CD44 in cancer progression: therapeutic implications

CD44, a non-kinase transmembrane glycoprotein, is overexpressed in several cell types including cancer stem cells and frequently shows alternative spliced variants that are thought to play a role in cancer development and progression. Hyaluronan, the main ligand for CD44, binds to and activates CD44 resulting in activation of cell signaling pathways that induces cell proliferation, increases cell survival, modulates cytoskeletal changes, and enhances cellular motility. The different functional roles of CD44 standard (CD44s) and specific CD44 variant (CD44v) isoforms are not fully understood. CD44v contain additional peptide motifs that can interact with and sequester growth factors and cytokines at the cell surface thereby functioning as coreceptors to facilitate cell signaling. Moreover, CD44v were expressed in metastasized tumors, whereas switching between CD44v and CD44s may play a role in regulating epithelial to mesenchymal transition (EMT) and in the adaptive plasticity of cancer cells. Here, we review current data on the structural and functional properties of CD44, the known roles for CD44 in tumorigencity, the regulation of CD44 expression, and the potential for targeting CD44 for cancer therapy.

Impairment of K-Ras signaling networks and increased efficacy of epidermal growth factor receptor inhibitors by a novel synthetic miR-143

Despite considerable research on K‐Ras inhibitors, none had been established until now. We synthesized nuclease‐resistant synthetic miR‐143 (miR‐143#12), which strongly silenced K‐Ras, its effector signal molecules AKT and ERK, and the K‐Ras activator Sos1. We examined the anti‐proliferative effect of miR‐143#12 and the mechanism in human colon cancer DLD‐1 cell (G13D) and other cell types harboring K‐Ras mutations. Cell growth was markedly suppressed in a concentration‐dependent manner by miR‐143#12 (IC₅₀: 1.32 nmol L⁻¹) with a decrease in the K‐Ras mRNA level. Interestingly, this mRNA level was also downregulated by either a PI3K/AKT or MEK inhibitor, which indicates a positive circuit of K‐Ras mRNA expression. MiR‐143#12 silenced cytoplasmic K‐Ras mRNA expression and impaired the positive circuit by directly targeting AKT and ERK mRNA. Combination treatment with miR‐143#12 and a low‐dose EGFR inhibitor induced a synergistic inhibition of growth with a marked inactivation of both PI3K/AKT and MAPK/ERK signaling pathways. However, silencing K‐Ras by siR‐KRas instead of miR‐143#12 did not induce this synergism through the combined treatment with the EGFR inhibitor. Thus, miR‐143#12 perturbed the K‐Ras expression system and K‐Ras activation by silencing Sos1 and, resultantly, restored the efficacy of the EGFR inhibitors. The in vivo results also supported those of the in vitro experiments. The extremely potent miR‐143#12 enabled us to understand K‐Ras signaling networks and shut them down by combination treatment with this miRNA and EGFR inhibitor in K‐Ras‐driven colon cancer cell lines.

Insulin-like growth factor-I induces chemoresistence to docetaxel by inhibiting miR-143 in human prostate cancer

Elevated levels of insulin-like growth factor-I (IGF-I) are associated with carcinogenesis and cancer progression. However, the molecular mechanisms by which IGF-I promotes prostate cancer development remain to be elucidated. Docetaxel chemotherapy is an important therapeutic strategy in many types of human cancers including prostate cancer. In this study, we showed that IGF-I rendered PC-3 and DU145 cells more resistant to docetaxel treatment. IGF-I treatment decreased miR-143 expression, but increased the expression levels of IGF-I receptor (IGF-IR) and insulin receptor substrate 1 (IRS1), direct targets of miR-143. Overexpression of miR-143 abolished IGF-I-induced chemoresistance to docetaxel treatment, decreased expression levels of IGF-I, IRS1, and vascular endothelial growth factor (VEGF) in prostate cancer cell lines. Furthermore, docetaxel treatment significantly inhibited VEGF transcriptional activation, whereas IGF-I treatment induced VEGF transcriptional activation in a dose-dependent manner. Forced expression of IGF-IR and IRS1 cDNAs without the 3’ UTR regions restored miR-143-inhibited VEGF transcriptional activation. Finally, miR-143 inhibited tumor growth and made cells more sensitive to docetaxel treatment for decreasing tumor growth in vivo. Taken together, our data demonstrates that IGF-I induces docetaxel resistance and upregulates IGF-IR and IRS1 expression through miR-143 downregulation, whereas miR-143 acts as a tumor suppressor by targeting its targets IGF-IR and IRS1.

MicroRNA‑3666 inhibits breast cancer cell proliferation by targeting sirtuin 7

The abnormal expression of microRNAs (miRNAs) is associated with cancer initiation and progression. miRNAs functioning as oncogenes or tumor suppressors represent novel biomarkers for cancer diagnosis, prognosis, and serve as therapeutic tools. MiR‑3666 has been reported as a tumor suppressor in various types of cancer; however, its role in breast cancer remains unknown. In the current study, the aim was to investigate the potential role of miR‑3666 in breast cancer. It was identified that miR‑3666 was decreased in breast cancer cell lines and that the overexpression of miR‑3666 inhibited breast cancer cell proliferation. Furthermore, miR‑3666 promotes cell apoptosis of breast cancer cells. Bioinformatics analysis and dual‑luciferase reporter assay demonstrated that miR‑3666 targeted the 3'‑untranslated region of sirtuin 7 (SIRT7) which was recognized as an oncogene. Overexpression of miR‑3666 decreased SIRT7 expression levels, and knockdown of SIRT7 suppressed proliferation and promoted apoptosis of breast cancer cells. A rescue assay demonstrated that the restoration of SIRT7 expression markedly reversed the miR‑3666‑induced anti‑tumor effects. Thus, the current study indicates that miR‑3666 suppresses breast cancer cell proliferation by targeting SIRT7, and propose miR‑3666 as a potential candidate for breast cancer therapy.

Establishment and Characterization of a Human Small Cell Osteosarcoma Cancer Stem Cell Line: A New Possible In Vitro Model for Discovering Small Cell Osteosarcoma Biology

Osteosarcoma (OSA) is the most common primary malignant bone tumor, usually arising in the long bones of children and young adults. There are different subtypes of OSA, among which we find the conventional OS (also called medullary or central osteosarcoma) which has a high grade of malignancy and an incidence of 80%. There are different subtypes of high grade OS like chondroblastic, fibroblastic, osteoblastic, telangiectatic, and the small cell osteosarcoma (SCO). In this study, for the first time, we have isolated, established, and characterized a cell line of cancer stem cells (CSCs) from a human SCO. First of all, we have established a primary finite cell line of SCO, from which we have isolated the CSCs by the sphere formation assay. We have proved their in vitro mesenchymal and embryonic stem phenotype. Additionally, we have showed their neoplastic phenotype, since the original tumor bulk is a high grade osteosarcoma. This research demonstrates the existence of CSCs also in human primary SCO and highlights the establishment of this particular stabilized cancer stem cell line. This will represent a first step into the study of the biology of these cells to discover new molecular targets molecules for new incisive therapeutic strategies against this highly aggressive OSA.