Dual role for miR-34a in the control of early progenitor proliferation and commitment in the mammary gland and in breast cancer

Serum Exosomes-Based Biomarker circ_0008928 Regulates Cisplatin Sensitivity, Tumor Progression, and Glycolysis Metabolism by miR-488/HK2 Axis in Cisplatin-Resistant Nonsmall Cell Lung Carcinoma

Background: Nonsmall cell lung carcinoma (NSCLC) is a major cause of cancer-related death worldwide. The resistance of NSCLC to chemical drugs, such as cisplatin (CDDP), poses a heavy burden for NSCLC therapy. Herein, the effects of circular_0008928 (circ_0008928) on the CDDP sensitivity and biological behavior of CDDP-resistant NSCLC cells and underlying mechanism are revealed. Materials and Methods: The expression of circ_0008928 and microRNA-488 (miR-488) was detected by quantitative real-time polymerase chain reaction. The expression of hexokinase 2 (HK2) protein and exosome-specific proteins was determined by Western blot. The half-maximal inhibitory concentration (IC50) value of CDDP was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation and migratory and invasive abilities were illustrated by cell counting kit-8 and transwell assays. Cell glycolysis metabolism was illustrated by extracellular acidification rate assay, glucose kit and lactate kit assays and Western blot analysis. The binding sites between miR-488 and circ_0008928 or HK2 were predicted by starbase or microT-CDS online database, and identified by dual-luciferase reporter and RNA immunoprecipitation assays. Results: Circ_0008928 expression and HK2 protein expression were significantly upregulated, while miR-488 expression was obviously downregulated in NSCLC cells and CDDP-resistant NSCLC cells. Circ_0008928 expression was increased in serum exosomes of CDDP-resistant NSCLC patients compared with CDDP-sensitive NSCLC patients. In addition, circ_0008928 silencing improved CDDP sensitivity and attenuated CDDP-induced cell proliferation, migration, invasion, and glycolysis metabolism. Circ_0008928 was a sponge of miR-488, and miR-488 bound to HK2 in CDDP-resistant NSCLC cells. Furthermore, both miR-488 inhibitor and HK2 overexpression attenuated circ_0008928 absence-mediated impacts on CDDP sensitivity and tumor process in CDDP-resistant NSCLC. Conclusions: Circ_0008928 knockdown improved CDDP sensitivity and hindered cell proliferation, migration, invasion, and glycolysis metabolism by miR-488/HK2 axis in CDDP-resistant NSCLC. This finding provides a new mechanism for studying CDDP-resistant therapy in NSCLC.

MicroRNA-34 Family in Cancers: Role, Mechanism, and Therapeutic Potential

MicroRNA (miRNA) are small noncoding RNAs that play vital roles in post-transcriptional gene regulation by inhibiting mRNA translation or promoting mRNA degradation. The dysregulation of miRNA has been implicated in numerous human diseases, including cancers. miR-34 family members (miR-34s), including miR-34a, miR-34b, and miR-34c, have emerged as the most extensively studied tumor-suppressive miRNAs. In this comprehensive review, we aim to provide an overview of the major signaling pathways and gene networks regulated by miR-34s in various cancers and highlight the critical tumor suppressor role of miR-34s. Furthermore, we will discuss the potential of using miR-34 mimics as a novel therapeutic approach against cancer, while also addressing the challenges associated with their development and delivery. It is anticipated that gaining a deeper understanding of the functions and mechanisms of miR-34s in cancer will greatly contribute to the development of effective miR-34-based cancer therapeutics.

Effect, sensitivity, specificity and accuracy of ultrasonic assessment of axillary lymph node-negative breast cancer

Objective

To investigate the diagnostic value of ultrasound for patients with axillary lymph node-negative breast cancer (ALNNBC).

Methods

A retrospective analysis was performed on the clinical data of 204 breast cancer patients who were admitted by Quanzhou First Hospital Affiliated to Fujian Medical University between October 2020 and May 2022. According to the results of axillary lymph node (ALN) examination, the patients were assigned to a positive group(n=102) and a negative group(n=102). All patients underwent diagnosis with color Doppler ultrasound, with pathological diagnosis as the "gold standard" to determine the sensitivity and specificity of ultrasonic diagnosis. A receiver operating characteristic(ROC) curve was established to analyze the efficiency of ultrasonic diagnosis and compare the ultrasonographic features and flow grades between the two groups.

Results

Differences were statistically significant between the two groups in ultrasonographic features of lesions(negative vs positive, all p<0.05), including morphological irregularity(59.8% vs 85.3%), spiky margins(19.6% vs 63.7%), posterior echo attenuation(19.6% vs 44.1%) and microcalcification(40.2% vs 55.89%). The negative group had a lower proportion of patients with grade 2-3 ultrasound blood flow when compared with the positive group(32.4% vs 56.86%), and the difference was statistically significant(p<0.05). Ultrasonic diagnosis of ALNNBC had a sensitivity of 88.24%(90/102), a specificity of 92.16%(94/102), a coincidence rate of 90.20% (184/204), a 95% CI of 0.845-0.928, and an AUC of 0.879.

Conclusions

Ultrasonic diagnosis of ALNNBC is relatively efficient as ultrasonographic features and ultrasound blood flow signals can provide a scientific basis for the diagnosis of ALNNBC.

MicroRNAs: A Link between Mammary Gland Development and Breast Cancer

Breast cancer is among the most common cancers in women, second to skin cancer. Mammary gland development can influence breast cancer development in later life. Processes such as proliferation, invasion, and migration during mammary gland development can often mirror processes found in breast cancer. MicroRNAs (miRNAs), small, non-coding RNAs, can repress post-transcriptional RNA expression and can regulate up to 80% of all genes. Expression of miRNAs play a key role in mammary gland development, and aberrant expression can initiate or promote breast cancer. Here, we review the role of miRNAs in mammary development and breast cancer, and potential parallel roles. A total of 32 miRNAs were found to be expressed in both mammary gland development and breast cancer. These miRNAs are involved in proliferation, metastasis, invasion, and apoptosis in both processes. Some miRNAs were found to have contradictory roles, possibly due to their ability to target many genes at once. Investigation of miRNAs and their role in mammary gland development may inform about their role in breast cancer. In particular, by studying miRNA in development, mechanisms and potential targets for breast cancer treatment may be elucidated.

Comparative Analysis of microRNAs that Stratify in vitro Mammary stem and Progenitor Activity Reveals Functionality of Human miR-92b-3p

Mammary stem/progenitor cells are fundamental for mammary gland development and function. However, much remains to be elucidated regarding their function in mammals beyond the traditionally studied rodents, human, and to a lesser extent, ruminants. Due to the growing appreciation for microRNAs (miRNAs) as regulators of stem cells and their progenitors, we compared miRNA expression in mammary stem/progenitor cells from mammals with varying mammary stem/progenitor activity in vitro, in order to identify miRNA candidates that regulate stem/progenitor self-renewal and function. Mammosphere-derived epithelial cells (MDECs), which are primary cell lines enriched in mammary stem and progenitor cells, were generated from six mammalian species (i.e., cow, human, pig, horse, dog, and rat) and small RNA sequencing was performed. We identified 9 miRNAs that were significantly differentially expressed in MDEC cultures with a low versus high mammary stem/progenitor activity. miR-92b-3p was selected for functional follow-up studies, as this miRNA is understudied in primary mammary cells but has well-described gene targets that are known to regulate mammary stem/progenitor activity. Altering the expression of miR-92b-3p in MDECs from species with low stem/progenitor activity (human and cow) and those with high stem/progenitor activity (dog and rat) via inhibition and overexpression, respectively, resulted in significantly decreased mammosphere formation of human MDECs, but showed no significant effects in cow, dog, or rat MDECs. This study is the first to perform small RNA sequencing in MDECs from various mammals and highlights that conserved miRNAs can have different functions in mammary stem/progenitor cells across species.

Cancer Stem Cells-The Insight into Non-Coding RNAs

Since their initial identification three decades ago, there has been extensive research regarding cancer stem cells (CSCs). It is important to consider the biology of cancer stem cells with a particular focus on their phenotypic and metabolic plasticity, the most important signaling pathways, and non-coding RNAs (ncRNAs) regulating these cellular entities. Furthermore, the current status of therapeutic approaches against CSCs is an important consideration regarding employing the technology to improve human health. Cancer stem cells have claimed to be one of the most important group of cells for the development of several common cancers as they dictate features, such as resistance to radio- and chemotherapy, metastasis, and secondary tumor formation. Therapies which could target these cells may develop into an effective strategy for tumor eradication and a hope for patients for whom this disease remains uncurable.

The metabolic addiction of cancer stem cells

Cancer stem cells (CSC) are the minor population of cancer originating cells that have the capacity of self-renewal, differentiation, and tumorigenicity (when transplanted into an immunocompromised animal). These low-copy number cell populations are believed to be resistant to conventional chemo and radiotherapy. It was reported that metabolic adaptation of these elusive cell populations is to a large extent responsible for their survival and distant metastasis. Warburg effect is a hallmark of most cancer in which the cancer cells prefer to metabolize glucose anaerobically, even under normoxic conditions. Warburg's aerobic glycolysis produces ATP efficiently promoting cell proliferation by reprogramming metabolism to increase glucose uptake and stimulating lactate production. This metabolic adaptation also seems to contribute to chemoresistance and immune evasion, a prerequisite for cancer cell survival and proliferation. Though we know a lot about metabolic fine-tuning in cancer, what is still in shadow is the identity of upstream regulators that orchestrates this process. Epigenetic modification of key metabolic enzymes seems to play a decisive role in this. By altering the metabolic flux, cancer cells polarize the biochemical reactions to selectively generate "onco-metabolites" that provide an added advantage for cell proliferation and survival. In this review, we explored the metabolic-epigenetic circuity in relation to cancer growth and proliferation and establish the fact how cancer cells may be addicted to specific metabolic pathways to meet their needs. Interestingly, even the immune system is re-calibrated to adapt to this altered scenario. Knowing the details is crucial for selective targeting of cancer stem cells by choking the rate-limiting stems and crucial branch points, preventing the formation of onco-metabolites.

Role of microRNA/lncRNA Intertwined With the Wnt/β-Catenin Axis in Regulating the Pathogenesis of Triple-Negative Breast Cancer

Objective (s): In this mini-review, we aimed to discuss the Wnt/β-catenin signaling pathway modulation in triple-negative breast cancer, particularly the contribution of lncRNAs and miRNAs in its regulation and their possible entwining role in breast cancer pathogenesis, proliferation, migration, or malignancy.

Background: Malignant tumor formation is very high for breast cancer in women and is a leading cause of death all over the globe. Among breast cancer subtypes, triple-negative breast cancer is rife in premenopausal women, most invasive, and prone to metastasis. Complex pathways are involved in this cancer’s pathogenesis, advancement, and malignancy, including the Wnt/β-catenin signaling pathway. This pathway is conserved among vertebrates and is necessary for sustaining cell homeostasis. It is regulated by several elements such as transcription factors, enhancers, non-coding RNAs (lncRNAs and miRNAs), etc.

Methods: We evaluated lncRNAs and miRNAs differentially expressed in triple-negative breast cancer (TNBC) from the cDNA microarray data set literature survey. Using in silico analyses combined with a review of the current literature, we anticipated identifying lncRNAs and miRNAs that might modulate the Wnt/β-catenin signaling pathway.

Result: The miRNAs and lncRNAs specific to triple-negative breast cancer have been identified based on literature and database searches. Tumorigenesis, metastasis, and EMT were all given special attention. Apart from cross-talk being essential for TNBC tumorigenesis and treatment outcomes, our results indicated eight upregulated and seven downregulated miRNAs and 19 upregulated and three downregulated lncRNAs that can be used as predictive or diagnostic markers. This consolidated information could be useful in the clinic and provide a combined literature resource for TNBC researchers working on the Wnt/β-catenin miRNA/lncRNA axis.

Conclusion: In conclusion, because the Wnt pathway and miRNAs/lncRNAs can modulate TNBC, their intertwinement results in a cascade of complex reactions that affect TNBC and related processes. Their function in TNBC pathogenesis has been highlighted in molecular processes underlying the disease progression.

Signaling pathways modulated by miRNAs in breast cancer angiogenesis and new therapeutics

MicroRNAs (miRNAs) act as oncogenes or tumor suppressors by suppressing the expression of target genes, some of which are engaged in angiogenic signaling pathways directly or indirectly. Tumor development and metastasis are dependent on angiogenesis, and it is the main reason for the poor prognosis of cancer patients. New blood vessels are formed from pre-existing vessels when angiogenesis occurs. Thus, it is essential to develop primary tumors and the spread of cancer to surrounding tissues. MicroRNAs (miRNAs) are small noncoding RNAs involved in various biological processes. They can bind to the 3'-UTR of their target genes and prevent them from expressing. MiRNAs control the activity of endothelial cells (ECs) through altering many biological pathways, which plays a key role in cancer progression and angiogenesis. Recent findings revealed that tumor-derived extracellular vesicles participated directly in the control of tumor angiogenesis by delivering miRNAs to ECs. miRNAs recently show great promise in cancer therapies to inhibit angiogenesis. In this study, we showed the miRNA-regulated signaling pathways in tumor angiogenesis with highlighting the anti-angiogenic therapy response and miRNA delivery methods that have been used to inhibit angiogenesis in both in vivo and in vitro studies.

MicroRNAs in Molecular Classification and Pathogenesis of Breast Tumors

The current clinical practice of breast tumor classification relies on the routine immunohistochemistry-based expression analysis of hormone receptors, which is inadequate in addressing breast tumor heterogeneity and drug resistance. MicroRNA expression profiling in tumor tissue and in the circulation is an efficient alternative to intrinsic molecular subtyping that enables precise molecular classification of breast tumor variants, the prediction of tumor progression, risk stratification and also identifies critical regulators of the tumor microenvironment. This review integrates data from protein, gene and miRNA expression studies to elaborate on a unique miRNA-based 10-subtype taxonomy, which we propose as the current gold standard to allow appropriate classification and separation of breast cancer into a targetable strategy for therapy.

Folate targeted hybrid lipo-polymeric nanoplexes containing docetaxel and miRNA-34a for breast cancer treatment

In spite of established evidence of the synergistic combination of hydrophobic anticancer molecule and microRNA for breast cancer treatment, their in vivo delivery has not been realized owing to their instability in the biological milieu and varied physicochemical properties. The present work reports folate targeted hybrid lipo-polymeric nanoplexes for co-delivering DTX and miR-34a. These nanoplexes exhibited a mean size of 129.3 nm with complexation efficiency at an 8:1 N/P ratio. The obtained nanoplexes demonstrated higher entrapment efficiency of DTX (94.8%) with a sustained release profile up to 85% till 48 h. Further, an improved transfection efficiency in MDA-MB-231 and 4T1 breast cancer cells was observed with uptake primarily through lipid-raft and clathrin-mediated endocytosis. Further, nanoplexes showed improved cytotoxicity (~3.5-5 folds), apoptosis (~1.6-2.0 folds), and change in expression of apoptotic genes (~4-7 folds) compared to the free treatment group in breast cancer cells. In vivo systemic administration of FA-functionalized DTX and FAM-siRNA-loaded nanoplexes showed an improved area under the curve (AUC) as well as circulation half-life compared to free DTX and naked FAM-labelled siRNA. Acute toxicity studies of the cationic polymer showed no toxicity at a dose equivalent to 10 mg/kg based on the hematological, biochemical, and histopathological examination.

Breast Cancer Response to Therapy: Can microRNAs Lead the Way?

Breast cancer (BC) is a leading cause of death among women with malignant diseases. The selection of adequate therapies for highly invasive and metastatic BCs still represents a major challenge. Novel combinatorial therapeutic approaches are urgently required to enhance the efficiency of BC treatment. Recently, microRNAs (miRNAs) emerged as key regulators of the complex mechanisms that govern BC therapeutic resistance and susceptibility. In the present review we aim to critically examine how miRNAs influence BC response to therapies, or how to use miRNAs as a basis for new therapeutic approaches. We summarized recent findings in this rapidly evolving field, emphasizing the challenges still ahead for the successful implementation of miRNAs into BC treatment while providing insights for future BC management.The goal of this review was to propose miRNAs, that might simultaneously improve the efficacy of all four therapies that are the backbone of current BC management (radio-, chemo-, targeted, and hormone therapy). Among the described miRNAs, miR-21 and miR-16 emerged as the most promising, closely followed by miR-205, miR-451, miR-182, and miRNAs from the let-7 family. miR-21 inhibition might be the best choice for future improvement of invasive BC treatment.New therapeutic strategies of miRNA-based agents alongside current standard treatment modalities could greatly benefit BC patients. This review represents a guideline on how to navigate this elaborate puzzle.

miR-34a-Mediated Survivin Inhibition Improves the Antitumor Activity of Selinexor in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive disease with limited therapeutic options. Here, we pursued a combinatorial therapeutic approach to enhance the activity of selinexor, the first-in-class XPO1 inhibitor, by miR-34a ectopic expression in human TNBC experimental models. Anti-proliferative activity induced by selinexor and miR-34a expression, singly and in combination, was evaluated by MTS assay and cell counting. The effect of treatments on survivin and apoptosis-related proteins was assessed by western blotting and ELISA. The antitumor and toxic effects of individual and combined treatments were evaluated on TNBC orthotopic xenografts in SCID mice. Selinexor consistently showed anti-proliferative activity, although to a variable extent, in the different TNBC cell lines and caused the impairment of survivin expression and intracellular distribution, accompanied by apoptosis induction. Consistent with in vitro data, the XPO1 inhibitor variably affected the growth of TNBC orthotopic xenografts. miR-34a cooperated with selinexor to reduce survivin expression and improved its anti-proliferative activity in TNBC cells. Most importantly, miR-34a expression markedly enhanced selinexor antitumor activity in the less sensitive TNBC xenograft model, in absence of toxicity. Our data form a solid foundation for promoting the use of a miR-34a-based approach to improve the therapeutic efficacy of selinexor in TNBC patients.

Signaling pathways governing breast cancer stem cells behavior

Breast cancer is the second common cancer and the leading cause of malignancy among females overall. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells that play a critical role in the metastasis of breast cancer to other organs in the body. BCSCs have both self-renewal and differentiation capacities, which are thought to contribute to the aggressiveness of metastatic lesions. Therefore, targeting BCSCs can be a suitable approach for the treatment and metastasis of breast cancer. Growing evidence has indicated that the Wnt, NFκB, Notch, BMP2, STAT3, and hedgehog (Hh) signaling pathways govern epithelial-to-mesenchymal transition (EMT) activation, growth, and tumorigenesis of BCSCs in the primary regions. miRNAs as the central regulatory molecules also play critical roles in BCSC self-renewal, metastasis, and drug resistance. Hence, targeting these pathways might be a novel therapeutic approach for breast cancer diagnosis and therapy. This review discusses known signaling mechanisms involved in the stimulation or prevention of BCSC self-renewal, metastasis, and tumorigenesis.

MicroRNA-34a: Potent Tumor Suppressor, Cancer Stem Cell Inhibitor, and Potential Anticancer Therapeutic

Overwhelming evidence indicates that virtually all treatment-naive tumors contain a subpopulation of cancer cells that possess some stem cell traits and properties and are operationally defined as cancer cell stem cells (CSCs). CSCs manifest inherent heterogeneity in that they may exist in an epithelial and proliferative state or a mesenchymal non-proliferative and invasive state. Spontaneous tumor progression, therapeutic treatments, and (epi)genetic mutations may also induce plasticity in non-CSCs and reprogram them into stem-like cancer cells. Intrinsic cancer cell heterogeneity and induced cancer cell plasticity, constantly and dynamically, generate a pool of CSC subpopulations with varying levels of epigenomic stability and stemness. Despite the dynamic and transient nature of CSCs, they play fundamental roles in mediating therapy resistance and tumor relapse. It is now clear that the stemness of CSCs is coordinately regulated by genetic factors and epigenetic mechanisms. Here, in this perspective, we first provide a brief updated overview of CSCs. We then focus on microRNA-34a (miR-34a), a tumor-suppressive microRNA (miRNA) devoid in many CSCs and advanced tumors. Being a member of the miR-34 family, miR-34a was identified as a p53 target in 2007. It is a bona fide tumor suppressor, and its expression is dysregulated and downregulated in various human cancers. By targeting stemness factors such as NOTCH, MYC, BCL-2, and CD44, miR-34a epigenetically and negatively regulates the functional properties of CSCs. We shall briefly discuss potential reasons behind the failure of the first-in-class clinical trial of MRX34, a liposomal miR-34a mimic. Finally, we offer several clinical settings where miR-34a can potentially be deployed to therapeutically target CSCs and advanced, therapy-resistant, and p53-mutant tumors in order to overcome therapy resistance and curb tumor relapse.

Epigenetics: New Insights into Mammary Gland Biology

The mammary gland undergoes important anatomical and physiological changes from embryogenesis through puberty, pregnancy, lactation and involution. These steps are under the control of a complex network of molecular factors, in which epigenetic mechanisms play a role that is increasingly well described. Recently, studies investigating epigenetic modifications and their impacts on gene expression in the mammary gland have been performed at different physiological stages and in different mammary cell types. This has led to the establishment of a role for epigenetic marks in milk component biosynthesis. This review aims to summarize the available knowledge regarding the involvement of the four main molecular mechanisms in epigenetics: DNA methylation, histone modifications, polycomb protein activity and non-coding RNA functions.

Interplay between HMGA and TP53 in cell cycle control along tumor progression

The high mobility group A (HMGA) proteins are found to be aberrantly expressed in several tumors. Studies (in vitro and in vivo) have shown that HMGA protein overexpression has a causative role in carcinogenesis process. HMGA proteins regulate cell cycle progression through distinct mechanisms which strongly influence its normal dynamics along malignant transformation. Tumor protein p53 (TP53) is the most frequently altered gene in cancer. The loss of its activity is recognized as the fall of a barrier that enables neoplastic transformation. Among the different functions, TP53 signaling pathway is tightly involved in control of cell cycle, with cell cycle arrest being the main biological outcome observed upon p53 activation, which prevents accumulation of damaged DNA, as well as genomic instability. Therefore, the interaction and opposing effects of HMGA and p53 proteins on regulation of cell cycle in normal and tumor cells are discussed in this review. HMGA proteins and p53 may reciprocally regulate the expression and/or activity of each other, leading to the counteraction of their regulation mechanisms at different stages of the cell cycle. The existence of a functional crosstalk between these proteins in the control of cell cycle could open the possibility of targeting HMGA and p53 in combination with other therapeutic strategies, particularly those that target cell cycle regulation, to improve the management and prognosis of cancer patients.

MicroRNA regulation of cancer stem cells in the pathogenesis of breast cancer

Breast cancer is the most common cancer among women and accounts for 30% of all female malignancies worldwide. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells that exhibit multiple characteristics including differentiation capacity, self-renewal and therapeutic resistance. Recently, BCSCs have attracted attention due to their modulation of breast tumor behaviors and drug resistance. miRNAs are small noncoding mRNAs involved in virtually all biological processes, including stem cell development, maintenance and differentiation. In breast cancer, miRNAs appear to be multi-faceted since they can act as either suppressors or oncogenes to regulate breast cancer progression. This review summarizes the critical roles of miRNAs in regulating multiple signaling pathways such as Wnt/β-catenin, Notch, PI3K/AKT/mTOR, BMI-1 and STAT3 that are important for the BCSC maintenance.

Exosomes derived from miR-34a-overexpressing mesenchymal stem cells inhibit in vitro tumor growth: A new approach for drug delivery

AIMS

Exosomes hold great promise as bio-inspired delivery vehicles. Mesenchymal stem cells (MSCs) are recognized for their potential to yield huge quantities of exosomes. We aimed to investigate the potential use of modified exosomes derived from genetically modified dental pulp MSCs (DPSCs) as a carrier to deliver tumor suppressor miR-34a to repress proliferation of breast carcinoma cells.

MATERIALS AND METHODS

miR-34a-overexpressing DPSCs were prepared using XMIRXpress-34a lentivectors. The anticancer effects of the miR-34a-loaded exosomes were evaluated on breast carcinoma cells through apoptosis, migration, and invasion assays. Given the structural similarity between exosomes and liposomes, we compared the exosome-mediated miRNA delivery efficiency with that of liposomes.

KEY FINDINGS

Our data demonstrated that genetically modified DPSCs were capable of secretion of exosomes enriched with therapeutic miRNAs and presented the feasibility of application of exosome-based vehicle for gene delivery.

SIGNIFICANCE

We showed the potential of MSC-derived exosomes as a tool for delivery of miRNAs in vitro. Nevertheless, optimizing gene-loading approaches is required before exosomes can be intended as a miRNA carrier for therapeutic applications.

Modulatory Role of microRNAs in Triple Negative Breast Cancer with Basal-Like Phenotype

Development of new research, classification, and therapeutic options are urgently required due to the fact that TNBC is a heterogeneous malignancy. The expression of high molecular weight cytokeratins identifies a biologically and clinically distinct subgroup of TNBCs with a basal-like phenotype, representing about 75% of TNBCs, while the remaining 25% includes all other intrinsic subtypes. The triple negative phenotype in basal-like breast cancer (BLBC) makes it unresponsive to endocrine therapy, i.e., tamoxifen, aromatase inhibitors, and/or anti-HER2-targeted therapies; for this reason, only chemotherapy can be considered an approach available for systemic treatment even if it shows poor prognosis. Therefore, treatment for these subgroups of patients is a strong challenge for oncologists due to disease heterogeneity and the absence of unambiguous molecular targets. Dysregulation of the cellular miRNAome has been related to huge cellular process deregulations underlying human malignancy. Consequently, epigenetics is a field of great promise in cancer research. Increasing evidence suggests that specific miRNA clusters/signatures might be of clinical utility in TNBCs with basal-like phenotype. The epigenetic mechanisms behind tumorigenesis enable progress in the treatment, diagnosis, and prevention of cancer. This review intends to summarize the epigenetic findings related to miRNAome in TNBCs with basal-like phenotype.

Targeting the intrinsically disordered architectural High Mobility Group A (HMGA) oncoproteins in breast cancer: learning from the past to design future strategies

INTRODUCTION

Triple-negative breast cancer (TNBC) is the most difficult breast cancer subtype to treat because of its heterogeneity and lack of specific therapeutic targets. High Mobility Group A (HMGA) proteins are chromatin architectural factors that have multiple oncogenic functions in breast cancer, and they represent promising molecular therapeutic targets for this disease.

AREAS COVERED

We offer an overview of the strategies that have been exploited to counteract HMGA oncoprotein activities at the transcriptional and post-transcriptional levels. We also present the possibility of targeting cancer-associated factors that lie downstream of HMGA proteins and discuss the contribution of HMGA proteins to chemoresistance.

EXPERT OPINION

Different strategies have been exploited to counteract HMGA protein activities; these involve interfering with their nucleic acid binding properties and the blocking of HMGA expression. Some approaches have provided promising results. However, some unique characteristics of the HMGA proteins have not been exploited; these include their extensive protein-protein interaction network and their intrinsically disordered status that present the possibility that HMGA proteins could be involved in the formation of proteinaceous membrane-less organelles (PMLO) by liquid-liquid phase separation. These unexplored characteristics could open new pharmacological avenues to counteract the oncogenic contributions of HMGA proteins.

A mechanism for epithelial-mesenchymal heterogeneity in a population of cancer cells

Epithelial-mesenchymal heterogeneity implies that cells within the same tumor can exhibit different phenotypes-epithelial, mesenchymal, or one or more hybrid epithelial-mesenchymal phenotypes. This behavior has been reported across cancer types, both in vitro and in vivo, and implicated in multiple processes associated with metastatic aggressiveness including immune evasion, collective dissemination of tumor cells, and emergence of cancer cell subpopulations with stem cell-like properties. However, the ability of a population of cancer cells to generate, maintain, and propagate this heterogeneity has remained a mystifying feature. Here, we used a computational modeling approach to show that epithelial-mesenchymal heterogeneity can emerge from the noise in the partitioning of biomolecules (such as RNAs and proteins) among daughter cells during the division of a cancer cell. Our model captures the experimentally observed temporal changes in the fractions of different phenotypes in a population of murine prostate cancer cells, and describes the hysteresis in the population-level dynamics of epithelial-mesenchymal plasticity. The model is further able to predict how factors known to promote a hybrid epithelial-mesenchymal phenotype can alter the phenotypic composition of a population. Finally, we used the model to probe the implications of phenotypic heterogeneity and plasticity for different therapeutic regimens and found that co-targeting of epithelial and mesenchymal cells is likely to be the most effective strategy for restricting tumor growth. By connecting the dynamics of an intracellular circuit to the phenotypic composition of a population, our study serves as a first step towards understanding the generation and maintenance of non-genetic heterogeneity in a population of cancer cells, and towards the therapeutic targeting of phenotypic heterogeneity and plasticity in cancer cell populations.

Notch1 in Tumor Microvascular Endothelial Cells and Tumoral miR-34a as Prognostic Markers in Locally Advanced Triple-Negative Breast Cancer

Purpose

Triple-negative breast cancer (TNBC) is associated with poor prognosis with limited treatment options. Angiogenesis is known to be involved in the progression of TNBC, and targeting this pathway results in modest clinical benefits. In this study, we analyzed the role of tumor microvascular endothelial Notch1 (EC Notch1) and tumoral miR-34a as prognostic markers in patients with TNBC.

Methods

The expression of miR-34a was analyzed using archival tumor tissues from 114 patients with TNBC. Simultaneously, archival tumor tissues were also checked for the expression of CD34 and Notch1 by immunostaining. The ratio of Notch1-microvascular density (MVD) to CD34-MVD was defined as EC Notch1. The association between the expression of miR-34a or EC Notch1 and clinicopathological characteristics was analyzed.

Results

In the overall patient population, patients with low expression of EC Notch1 was associated with better overall survival (OS, p = 0.041) than those with high expression of EC Notch1. In lymph node-positive TNBC patients, high levels of miR-34a and low levels of EC Notch1 correlated significantly with higher survival benefits in terms of OS (p = 0.026), disease-free survival (p = 0.009), and metastasis-free survival (p = 0.038) relative to that in other patients. Decreased expression of EC Notch1 and increased expression of miR-34a also showed a survival benefit in locally advanced TNBC.

Conclusion

The fact that miR-34a and EC Notch1 are associated with the angiogenesis suggests that angiogenesis may play a role in the development and progression of TNBC.

Polymeric Hybrid Nanomicelles for Cancer Theranostics: An Efficient and Precise Anticancer Strategy for the Codelivery of Doxorubicin/miR-34a and Magnetic Resonance Imaging

To realize precise tumor therapy, a versatile oncotherapy nanoplatform integrating both diagnostic and therapeutic functions is necessary. Herein, we fabricated a hybrid micelle (HM) utilizing two amphiphilic diblock copolymers, polyethylenimine-polycaprolactone (PEI-PCL) and diethylenetriaminepentaacetic acid gadolinium(III)  (Gd-DTPA)-conjugated polyethyleneglycol-polycaprolactone (Gd-PEG-PCL), to codeliver the small-molecule chemotherapy drugs doxorubicin (Dox) and microRNA-34a (miR-34a), denoted as Gd-HM-Dox/34a. Conjugating Gd-DTPA on the surface of hybrid micelles, leading the relaxation rate of Gd-DTPA increased more than 1.4 times (13.6 mM^-1 S^-1). Furthermore, hybrid micelles enhanced the ability of miR-34a to escape from lysosomes/endosomes and Dox release to the nucleus. In addition, the released miR-34a subsequently downregulates Bcl-2, cyclin D1, CDK6, and Bax expression and inhibits proliferation and migration of MDA-MB-231 breast cancer cells. Moreover, the suitable micelle size improved the penetration of Dox into three-dimensional (3D) multicellular spheroids compared with Gd-HM-Dox and Free Dox, generating efficient cell killing in the 3D multicellular spheroids. Furthermore, the Gd-HM-Dox/34a exhibited augmented accumulation in the tumor tissue, which improved the magnetic resonance (MR) imaging contrast of solid tumors and enhanced the combined efficiency of chemotherapeutic drugs Dox and therapeutic gene miR-34a in suppressing tumor growth on MDA-MB-231 tumor-bearing mice. Therefore, we established a hybrid micelle to offer a promising theranostic approach that inhibits tumor growth and enhances MR imaging.

Fluorescence imaging of a potential diagnostic biomarker for breast cancer cells using a peptide-functionalized fluorogenic 2D material

Protein C receptor (PROCR) is a recently discovered transmembrane biomarker for several tissue stem cells and is highly expressed in triple-negative breast cancer (TNBC) patient-derived xenografts. Herein, to enrich the toolbox for the biochemical evaluation of PROCR, we have developed a peptide-functionalized fluorogenic 2D material based on the self-assembly between a fluorescent peptide probe and thin-layer molybdenum disulfide. The material developed was suitable for the sensitive detection of PROCR recombinant protein in buffer solution and the fluorescence imaging of TNBC cells that express high levels of PROCR.

The DNMT1/miR-34a Axis Is Involved in the Stemness of Human Osteosarcoma Cells and Derived Stem-Like Cells

The DNA methyltransferase 1 (DNMT1)/miR-34a axis promoted carcinogenesis of various types of cancers. However, no literature reported its contribution to the stemness of osteosarcoma cancer stem-like cells (OSLCs). We sought to determine whether the DNMT1/miR-34a axis facilitates the stemness of OSLCs. We here revealed the higher DNMT1 activity and expression, lower miR-34a expression with high methylation of its promoter, and stronger stemness of OSLCs, as manifested by elevated sphere and colony formation capacities; CD133, CD44, ABCG2, Bmi1, Sox2, and Oct4 protein amounts in vitro; and carcinogenicity in a nude mouse xenograft model, when compared to the parental U2OS cells. 5-Azacytidine (Aza-dC) repressed DNMT1 activation and upregulated miR-34a expression by promoter demethylation and suppressed the stemness of OSLCs in a dose-dependent manner. DNMT1 knockdown increased miR-34a and reduced the stemness of OSLCs. Transfection with a miR-34a mimic repressed the stemness of OSLCs but did not alter DNMT1 activity and expression. Conversely, DNMT1 overexpression declined miR-34a levels, promoting the stemness of U2OS cells. Transfection with a miR-34a inhibitor enhanced the stemness of U2OS cells, without affecting the DNMT1 activity and expression. Importantly, reexpression of miR-34a could rescue the effects of DNMT1 overexpression on miR-34a inhibition as well as the stemness promotion without affecting the activity and expression of DNMT1. Our results revealed that aberrant activation of DNMT1 caused promoter methylation of miR-34a, leading to miR-34a underexpression, and the role of the DNMT1/miR-34a axis in promoting and sustaining the stemness of OSLCs.

miR-34b/c regulates doxorubicin-induced myocardial cell injury through ITCH

Objective: To determine the underlying mechanism of miR-34b/c in regulating doxorubicin (Dox)-induced myocardial cell injury.Methods: The viability of mouse myocardial cells HL-1 was detected by MTT assay. The apoptosis of HL-1 cells was detected by TUNEL assay. mRNA expressions of ITCH, TNF-α and IL-6 were measured by qRT-PCR. Protein levels of ITCH, NF-κB, TNF-α and IL-6 were measured by western blot. Dual luciferase assay was performed to detect the regulation of miR-34b/c on ITCH. Mouse model of cardiomyopathy was induced by intraperitoneal injection of Dox.Results: Dox reduced HL-1 cell viability and activated NF-κB pathway in HL-1 cells. miR-34b/c expressions were gradually up-regulated and ITCH expression was gradually down-regulated in Dox-treated HL-1 cells. miR-34b/c expression had negative correlation with the mRNA expression of ITCH. Besides, ITCH was a target of miR-34b/c. miR-34b/c mimic reduced cell viability, suppressed ITCH expression, increased TNF-α and IL-6 level, and promoted NF-κB expression in nucleus and cytoplasm of HL-1 cells. Whereas silencing miR-34 protected HL-1 cells through regulating ITCH. Finally, we demonstrated miR-34 antagomir-protected myocardial cells in mouse model of cardiomyopathy.Conclusion: miR-34b/c decreased HL-1 cell viability and promoted the secretion of proinflammatory cytokines in Dox-induced myocardial cells through ITCH/NF-κB pathway.

Role of miRNA-Regulated Cancer Stem Cells in the Pathogenesis of Human Malignancies

Recent biomedical discoveries have revolutionized the concept and understanding of carcinogenesis, a complex and multistep phenomenon which involves accretion of genetic, epigenetic, biochemical, and histological changes, with special reference to MicroRNAs (miRNAs) and cancer stem cells (CSCs). miRNAs are small noncoding molecules known to regulate expression of more than 60% of the human genes, and their aberrant expression has been associated with the pathogenesis of human cancers and the regulation of stemness features of CSCs. CSCs are the small population of cells present in human malignancies well-known for cancer resistance, relapse, tumorigenesis, and poor clinical outcome which compels the development of novel and effective therapeutic protocols for better clinical outcome. Interestingly, the role of miRNAs in maintaining and regulating the functioning of CSCs through targeting various oncogenic signaling pathways, such as Notch, wingless (WNT)/β-Catenin, janus kinases/ signal transducer and activator of transcription (JAK/STAT), phosphatidylinositol 3-kinase/ protein kinase B (PI3/AKT), and nuclear factor kappa-light-chain-enhancer of activated B (NF-kB), is critical and poses a huge challenge to cancer treatment. Based on recent findings, here, we have documented the regulatory action or the underlying mechanisms of how miRNAs affect the signaling pathways attributed to stemness features of CSCs, such as self-renewal, differentiation, epithelial to mesenchymal transition (EMT), metastasis, resistance and recurrence etc., associated with the pathogenesis of various types of human malignancies including colorectal cancer, lung cancer, breast cancer, head and neck cancer, prostate cancer, liver cancer, etc. We also shed light on the fact that the targeted attenuation of deregulated functioning of miRNA related to stemness in human carcinogenesis could be a viable approach for cancer treatment.

Delivery of biologically active miR-34a in normal and cancer mammary epithelial cells by synthetic nanoparticles

Functional RNAs, such as microRNAs, are emerging as innovative tools in the treatment of aggressive and incurable cancers. In this study, we explore the potential of silica dioxide nanoparticles (SiO₂NPs) in the delivery of biologically active miRNAs. Focusing on the tumor-suppressor miR-34a, we evaluated miRNAs delivery by SiO₂NPs into the mammary gland, using in vitro as well as in vivo model systems. We showed that silica nanoparticles can efficiently deliver miR-34a into normal and cancer epithelial cells grown in culture without major signs of toxicity. Delivered miRNA retained the ability to silence artificial as well endogenous targets and can reduce the growth of mammospheres in 3D culture. Finally, miR-34a delivery through intra-tumor administration of SiO₂NPs leads to a reduced mammary tumor growth. In conclusion, our studies suggest that silica nanoparticles can mediate the delivery of miR-34a directly into mammary tumors while preserving its molecular and biological activity.

Roles of MicroRNA-34a in Epithelial to Mesenchymal Transition, Competing Endogenous RNA Sponging and Its Therapeutic Potential

MicroRNA-34a (miR-34a), a tumor suppressor, has been reported to be dysregulated in various human cancers. MiR-34a is involves in certain epithelial-mesenchymal transition (EMT)-associated signal pathways to repress tumorigenesis, cancer progression, and metastasis. Due to the particularity of miR-34 family in tumor-associated EMT, the significance of miR-34a is being increasingly recognized. Competing endogenous RNA (ceRNA) is a novel concept involving mRNA, circular RNA, pseudogene transcript, and long noncoding RNA regulating each other’s expressions using microRNA response elements to compete for the binding of microRNAs. Studies showed that miR-34a is efficient for cancer therapy. Here, we provide an overview of the function of miR-34a in tumor-associated EMT. ceRNA hypothesis plays an important role in miR-34a regulation in EMT, cancer progression, and metastasis. Its potential roles and challenges as a microRNA therapeutic candidate are discussed. As the negative effect on cancer progression, miR-34a should play crucial roles in clinical diagnosis and cancer therapy.

MicroRNA-34 family: a potential tumor suppressor and therapeutic candidate in cancer

MicroRNA-34 (miR-34) has been reported to be dysregulated in various human cancers and regarded as a tumor suppressive microRNA because of its synergistic effect with the well-known tumor suppressor p53. Along with the application of MRX34, the first tumor-targeted microRNA drug which based on miR-34a mimics, on phase I clinical trial (NCT01829971), the significance of miR-34 is increasingly recognized. miR-34 plays a crucial role on repressing tumor progression by involving in epithelial-mesenchymal transition (EMT) via EMT- transcription factors, p53 and some important signal pathways. Not only that, numerous preclinical researches revealed the giant potential of miR-34a on cancer therapy through diversiform nano-scaled delivery systems. Here, we provide an overview about the function of miR-34 in various cancers and the mechanism of miR-34 in tumor-associated EMT. Furthermore, its potential role as a microRNA therapeutic candidate is also discussed. Notwithstanding some obstacles existed, the extensive application prospect of miR-34 on oncotherapy cannot be neglected.

Development of double strand RNA mPEI nanoparticles and application in treating invasive breast cancer

dsRNA mPEI nanoparticles entered cytoplasm and lysosomal escape occurred. dsRNA was released to form a dsRNA–RISC complex. Then, remaining sense strand bound to mRNA, forming a new structure. Thus, mRNA was cleared and translation was inhibited.