miR-200c inhibits breast cancer proliferation by targeting KRAS

Unraveling the metastasis-preventing effect of miR-200c in vitro and in vivo

Advanced breast cancer, as well as ineffective treatments leading to surviving cancer cells, can result in the dissemination of these malignant cells from the primary tumor to distant organs. Recent research has shown that microRNA 200c (miR-200c) can hamper certain steps of the invasion-metastasis cascade. However, it is still unclear whether miR-200c expression alone is sufficient to prevent breast cancer cells from metastasis formation. Hence, we performed a xenograft mouse experiment with inducible miR-200c expression in MDA-MB 231 cells. The ex vivo analysis of metastatic sites in a multitude of organs, including lung, liver, brain, and spleen, revealed a dramatically reduced metastatic burden in mice with miR-200c-expressing tumors. A fundamental prerequisite for metastasis formation is the motility of cancer cells and, therefore, their migration. Consequently, we analyzed the effect of miR-200c on collective- and single-cell migration in vitro, utilizing MDA-MB 231 and MCF7 cell systems with genetically modified miR-200c expression. Analysis of collective-cell migration revealed confluence-dependent motility of cells with altered miR-200c expression. Additionally, scratch assays showed an enhanced predisposition of miR-200c-negative cells to leave cell clusters. The in-between stage of collective- and single-cell migration was validated using transwell assays, which showed reduced migration of miR-200c-positive cells. Finally, to measure migration at the single-cell level, a novel assay on dumbbell-shaped micropatterns was performed, which revealed that miR-200c critically determines confined cell motility. All of these results demonstrate that sole expression of miR-200c impedes metastasis formation in vivo and migration in vitro and highlights miR-200c as a metastasis suppressor in breast cancer.

Non-coding RNAs, a double-edged sword in breast cancer prognosis

Cancer is a rising issue worldwide, and numerous studies have focused on understanding the underlying reasons for its occurrence and finding proper ways to defeat it. By applying technological advances, researchers are continuously uncovering and updating treatments in cancer therapy. Their vast functions in the regulation of cell growth and proliferation and their significant role in the progression of diseases, including cancer. This review provides a comprehensive analysis of ncRNAs in breast cancer, focusing on long non-coding RNAs such as HOTAIR, MALAT1, and NEAT1, as well as microRNAs such as miR-21, miR-221/222, and miR-155. These ncRNAs are pivotal in regulating cell proliferation, metastasis, drug resistance, and apoptosis. Additionally, we discuss experimental approaches that are useful for studying them and highlight the advantages and challenges of each method. We then explain the results of these clinical trials and offer insights for future studies by discussing major existing gaps. On the basis of an extensive number of studies, this review provides valuable insights into the potential of ncRNAs in cancer therapy. Key findings show that even though the functions of ncRNAs are vast and undeniable in cancer, there are still complications associated with their therapeutic use. Moreover, there is an absence of sufficient experiments regarding their application in mouse models, which is an area to work on. By emphasizing the crucial role of ncRNAs, this review underscores the need for innovative approaches and further studies to explore their potential in cancer therapy.

MicroRNA-200c in Cancer Generation, Invasion, and Metastasis

MicroRNA-200c (miR-200c) is increasingly recognized as a crucial small RNA molecule that plays a significant and multifaceted role in the complex processes of tumor development, invasion, and metastasis across various types of cancers. Recent studies have compellingly demonstrated that miR-200c exerts its influence on tumor biology by meticulously regulating a range of critical processes, including cell proliferation, apoptosis, epithelial-mesenchymal transition (EMT), and cell migration, all of which are essential for the progression and aggressiveness of tumors. This comprehensive review aims to summarize the expression characteristics and functional implications of miR-200c across a diverse array of tumor types, delving into its potential utility as both a biomarker for early detection and a therapeutic target in the realm of cancer treatment. By synthesizing current research findings and insights, we aspire to provide valuable information that could significantly enhance early diagnostic capabilities and inform the strategic development of targeted therapy approaches in oncology.

Molecular Insights on Signaling Cascades in Breast Cancer: A Comprehensive Review

The complex signaling network within the breast tumor microenvironment is crucial for its growth, metastasis, angiogenesis, therapy escape, stem cell maintenance, and immunomodulation. An array of secretory factors and their receptors activate downstream signaling cascades regulating breast cancer progression and metastasis. Among various signaling pathways, the EGFR, ER, Notch, and Hedgehog signaling pathways have recently been identified as crucial in terms of breast cancer proliferation, survival, differentiation, maintenance of CSCs, and therapy failure. These receptors mediate various downstream signaling pathways such as MAPK, including MEK/ERK signaling pathways that promote common pro-oncogenic signaling, whereas dysregulation of PI3K/Akt, Wnt/β-catenin, and JAK/STAT activates key oncogenic events such as drug resistance, CSC enrichment, and metabolic reprogramming. Additionally, these cascades orchestrate an intricate interplay between stromal cells, immune cells, and tumor cells. Metabolic reprogramming and adaptations contribute to aggressive breast cancer and are unresponsive to therapy. Herein, recent insights into the novel signaling pathways operating within the breast TME that aid in their advancement are emphasized and current developments in practices targeting the breast TME to enhance treatment efficacy are reviewed.

Serum exosomal miR-200c is a potential diagnostic biomarker for breast cancer

BACKGROUND

Breast cancer (BC) is one of the most common malignancies in women. Exosomes are widely found in body fluids and carry microRNAs (miRNAs) that reflect the biological properties of the parental cells. Our study aimed to investigate the differential expression of miR-200c in BC serum exosomes and its diagnostic value.

METHODOLOGY

miRNA profiles in culture supernatant exosomes of normal mammary epithelial cells MCF-10A and BC cells (MCF-7, MDA-MB-231, MCF-7 Taxol) were examined by miRNA deep sequencing to screen for significantly differentially expressed miRNAs; Transmission electron microscopy (TEM), Nanoparticle tracking analysis (NTA), and Western blot were used to identify exosomes; qPCR was used to detect the expression level of miR-200c in cellular exosomes and serum exosomes; The efficacy of individual and combined tests of each indicator to diagnose BC was evaluated using receiver operating characteristic (ROC) curves.

RESULTS

We identified typical exosome features by TEM, NTA and Western blot, indicating successful exosome extraction. Then our miRNA sequencing results and qRT-PCR experiments showed that miR-200c was significantly down-regulated in BC cell exosomes. In addition, we divided the clinical serum samples into two cohorts according to region, and in independent cohort I, the serum exosomal miR-200c levels of BC patients were significantly lower than those of healthy controls. In cohort II, serum exosomal miR-200c expression was significantly lower in the BC group than in the control and benign breast disease (BBD) groups, whereas miR-200c expression in the BBD group was not statistically different from that in the control group. ROC analyses in both independent cohorts confirmed that serum exosomal miR-200c could differentiate between patients with and without BC disease and could be used as an early diagnostic marker for BC disease.

CONCLUSION

Serum exosome miR-200c can be used as a potential biomarker for the diagnosis of BC, and combined with conventional serum diagnostic markers AFP, CA125 and CA153 can help to improve diagnostic efficiency.

miR-200c targeting GLI3 inhibits cell proliferation and promotes apoptosis in non-small cell lung cancer cells

Lung cancer is a common malignant tumor with low cure rate. It has an easy recurrence and metastasis. This study explored whether miR-200c could regulate the biological behavior of non-small cell lung cancer cells through targeting GLI3. Luciferase reporter gene analysis was used to verify the interaction between miR-200c-3p and GLI3. miR-200c-3p and GLI3 were transiently overexpressed into A549 cells. The cell viability rate was detected by cell counting kit-8, cell invasion ability was detected with Transwell, cell apoptosis and cell cycle was determined by flow cytometry, and the expression of GLI3 was detected using quantitative polymerase chain reaction and Western blot, to verify the effect of the interaction between miR-200c-3p and GLI3 on the cell activities. miR-200c-3p overexpression could inhibit cell viability and invasion, promote apoptosis, induce G0/G1 arrest, and inhibit cell division. GLI3 overexpression could reverse the miR-200c-3p inhibition on cell cycle, reduce the number of cells in the G0/G1 phase and increase the number of cells in the S phase. miR-200c-3p overexpression in A549 cells could inhibit cell viability and invasion, and promote apoptosis. miR-200c-3p could target GLI3 to regulate cell cycle and inhibit cell proliferation.

BRCA Mutations and MicroRNA Expression Patterns in the Peripheral Blood of Breast Cancer Patients

Breast cancer (BC) persists as the predominant malignancy globally, standing as the foremost cause of cancer-related mortality among women. Despite notable advancements in prevention and treatment, encompassing the incorporation of targeted immunotherapies, a continued imperative exists for the development of innovative methodologies. These methodologies would facilitate the identification of women at heightened risk, enhance the optimization of therapeutic approaches, and enable the vigilant monitoring of emergent treatment resistance. Circulating microRNAs (miRNAs), found either freely circulating in the bloodstream or encapsulated within extracellular vesicles, have exhibited substantial promise for diverse clinical applications. These applications range from diagnostic and prognostic assessments to predictive purposes. This study aimed to explore the potential associations between BRCA mutations and specific miRNAs (miR-21, miR-155, miR-126, and miR-200c) expression that are known to be dysregulated in BC patient samples. Our findings indicate a robust correlation between miRNA expression status and disease subtypes. We found a correlation between the expression status of miRNAs and distinct disease subtypes. Intriguingly, however, no significant associations were discerned between disease status, subtypes, or miRNA expression levels and the presence of BRCA mutations. To advance the validation of miRNAs as clinically relevant biomarkers, additional investigations within larger and meticulously selected patient cohorts are deemed imperative. These microRNA entities hold the potential to emerge as groundbreaking and readily accessible tools, poised for seamless integration into the landscape of clinical practice.

Exploring the contrasts: in-depth analysis of human and canine mammary tumors - discoveries at the frontier

We have examined genomic and transcriptomic abnormalities in human and canine samples to evaluate the canine model's validity for breast cancer research, emphasizing similarities and differences. Both species commonly utilize serum tumor markers and noncoding microRNAs. Immunohistochemistry and immunocytochemistry were employed to illustrate and compare results based on histological diagnoses. In addition to these factors, similarities exist in spontaneous tumor occurrence, age of onset, hormonal influences, and disease progression, including tumor size, clinical stage, and lymph node involvement. Molecular traits such as hormone receptor status, Epidermal Growth Factor Receptor (EGFR), and proliferation markers (Ki67) further endorse the canine model's utility in breast cancer studies. The advancement of technologies facilitates the identification of new cancer-associated molecules, both coding and non-coding genes, underscoring their potential as prognostic/diagnostic biomarkers and therapeutic targets.

microRNAs and their therapeutic strategy in phase I and phase II clinical trials

miRNAs play a crucial therapeutic role in diseases such as cancer, diabetes and viral infections, with around 1900 identified in the human genome. Some have progressed to clinical trials, and miRNA mimics and miRNA inhibitors are pivotal therapeutic molecules undergoing evaluation. The review delves into various miRNA-associated clinical trials, emphasizing their precision in targeting specific genes, modulating disease pathways and diagnostic potential. This underscores the importance of miRNA therapy, foreseeing innovations in precision medicine techniques for diverse diseases. The future envisions improved delivery systems addressing challenges like immunogenicity and digestion, while a comprehensive miRNA-based omics database could guide the development of tailored antisense miRNAs, further advancing precision medicine strategies.

Delivery of miR-200c-3p Using Tumor-Targeted Mesoporous Silica Nanoparticles for Breast Cancer Therapy

Despite advances in breast cancer treatment, it remains the leading cause of cancer-related death in women worldwide. In this context, microRNAs have emerged as potential therapeutic targets but still present some limitations for in vivo applications. Particularly, miR-200c-3p is a well-known tumor suppressor microRNA that inhibits tumor progression and metastasis in breast cancer through downregulating ZEB1 and ZEB2. Based on the above, we describe the design and validation of a nanodevice using mesoporous silica nanoparticles for miR-200c-3p delivery for breast cancer treatment. We demonstrate the biocompatibility of the synthesized nanodevices as well as their ability to escape from endosomes/lysosomes and inhibit tumorigenesis, invasion, migration, and proliferation of tumor cells in vitro. Moreover, tumor targeting and effective delivery of miR-200c-3p from the nanoparticles in vivo are confirmed in an orthotopic breast cancer mouse model, and the therapeutic efficacy is also evidenced by a decrease in tumor size and lung metastasis, while showing no signs of toxicity. Overall, our results provide evidence that miR-200c-3p-loaded nanoparticles are a potential strategy for breast cancer therapy and a safe and effective system for tumor-targeted delivery of microRNAs.

The dynamic tumor-stromal crosstalk: implications of 'stromal-hot' tumors in the process of epithelial-mesenchymal transition in breast cancer

BACKGROUND

Breast cancer metastatic programming involves an intricate process by which the tumor cell coevolves with the surrounding extracellular niche. The supporting cells from the local host stroma get transformed into cancer-associated stromal cells. This complex crosstalk leads to extracellular matrix remodeling, invasion, and eventually distant metastasis.

METHODS

In this review, we examine the protein-miRNA secretome that is crucial for this crosstalk. We also provide evidence from the literature for the pivotal role played by the various stromal cells like fibroblasts, adipocytes, and immune cells in promoting the process of EMT in breast cancer. Through in-silico analysis, we have also attempted to establish that stromal presence is integral to the process of EMT.

RESULTS AND CONCLUSION

The in-silico analysis delineates the persuasive role of the stroma in mediating epithelial-to-mesenchymal transition. This review elucidates the importance of examining the role of the stromal niche that can yield promising diagnostic markers and pave avenues for formulating tailored anti-cancer therapy. Process of EMT as driven by 'stroma-hot' tumors: The process of EMT is driven by the stromal cells. The stromal cells in the form of  fibroblasts, adipocytes, endothelial cells, mesenchymal stromal cells and tissue associated macrophages secrete the miRNA-protein secretome that modulates the stromal niche and the tumor cells to be become 'tumor associated'. This drives tumor progression and invasion. The 'stromal-hot' tumors eventually get the benefit of the surplus nurturing from the stroma that facilitates EMT leading to distant organ seeding and metastasis.

Unraveling Roles of miR-27b-3p as a Potential Biomarker for Breast Cancer in Malay Women via Bioinformatics Analysis

Abnormal miRNA expression has been associated with breast cancer. Knowing miRNA and its target genes gives a better understanding of the biological mechanism behind the development of breast cancer. Here, we evaluated the potential prognostic and predictive values of miRNAs in breast cancer development by analyzing Malay women with breast cancer expression profiles. Seven differentially expressed miRNAs (DEMs) were subjected to miRNA‒target interaction network analysis (MTIN). A comprehensive MTIN was developed by integrating the information on miRNA and target gene interactions from five independent databases, including DIANA-TarBase, miRTarBase, miRNet, miRDB, and DIANA-microT. To understand the role of miRNAs in the progress of breast cancer, functional enrichment analysis of the miRNA target genes was conducted, followed by survival analysis to assess the prognostic values of the miRNAs and their target genes. In total, 1416 interactions were discovered among seven DEMs and 1274 target genes with a confidence score (CS) > 0.8. The overall survival analysis of the three most DEMs revealed a significant association of miR-27b-3p with poor prognosis in the TCGA breast cancer patient cohort. Further functional analysis of 606 miR-27b-3p target genes revealed their involvement in cancer-related processes and pathways, including the progesterone receptor signaling pathway, PI3K-Akt pathway, and EGFR transactivation. Notably, six high-confidence target genes (BTG2, DNAJC13, GRB2, GSK3B, KRAS, and UBR5) were discovered to be associated with worse overall survival in breast cancer patients, underscoring their essential roles in breast cancer development. Thus, we suggest that miR-27b-3p has significant potential as a biomarker for detecting breast cancer and can provide valuable understanding regarding the molecular mechanisms of the disease.

Combating Drug Resistance by Exploiting miRNA-200c-Controlled Phase II Detoxification

Acquired drug resistance constitutes a serious obstacle to the successful therapy of cancer. In the process of therapy resistance, microRNAs can play important roles. In order to combat resistance formation and to improve the efficacy of chemotherapeutics, the mechanisms of the multifaceted hsa-miR-200c on drug resistance were elucidated. Upon knockout of hsa-miR-200c in breast carcinoma cells, a proteomic approach identified altered expression of glutathione S-transferases (GSTs) when cells were treated with the chemotherapeutic drug doxorubicin. In different hsa-miR-200c expression systems, such as knockout, inducible sponge and inducible overexpression, the differential expression of all members of the GST family was evaluated. Expression of hsa-miR-200c in cancer cells led to the repression of a multitude of these GSTs and as consequence, enhanced drug-induced tumor cell death which was evaluated for two chemotherapeutic drugs. Additionally, the influence of hsa-miR-200c on the glutathione pathway, which is part of the phase II detoxification mechanism, was investigated. Finally, the long-term effects of hsa-miR-200c on drug efficacy were studied in vitro and in vivo. Upon doxycycline induction of hsa-miR-200c, MDA-MB 231 xenograft mouse models revealed a strongly reduced tumor growth and an enhanced treatment response to doxorubicin. A combined treatment of these tumors with hsa-miR-200c and doxorubicin resulted in complete regression of the tumor in 60% of the animals. These results identify hsa-miR-200c as an important player regulating the cellular phase II detoxification, thus sensitizing cancer cells not expressing this microRNA to chemotherapeutics and reversing drug resistance through suppression of GSTs.

The role of miR-200 family in the regulation of hallmarks of cancer

MiRNAs are short non-coding RNAs that regulate gene expression post-transcriptionally contributing to the development of different diseases including cancer. The miR-200 family consists of five members, miR-200a, miR-200b, miR-200c, miR-141, and miR-429. Their expression is dysregulated in cancer tissue and their level is altered in the body fluids of cancer patients. Moreover, the levels of miR-200 family members correlate with clinical parameters such as cancer patients' survival which makes them potentially useful as diagnostic and prognostic biomarkers. MiRNAs can act as either oncomiRs or tumor suppressor miRNAs depending on the target genes and their role in the regulation of key oncogenic signaling pathways. In most types of cancer, the miR-200 family acts as tumor suppressor miRNA and regulates all features of cancer. In this review, we summarized the expression pattern of the miR-200 family in different types of cancer and their potential utility as biomarkers. Moreover, we comprehensively described the role of miR-200 family members in the regulation of all hallmarks of cancer proposed by Hanahan and Weinberg with the focus on the epithelial-mesenchymal transition, invasiveness, and metastasis of tumor cells.

The role of epigenetic modifications in drug resistance and treatment of breast cancer

Background

Breast cancer is defined as a biological and molecular heterogeneous disorder that originates from breast cells. Genetic predisposition is the most important factor giving rise to this malignancy. The most notable mutations in breast cancer occur in the BRCA1 and BRCA2 genes. Owing to disease heterogeneity, lack of therapeutic target, anti-cancer drug resistance, residual disease, and recurrence, researchers are faced with challenges in developing strategies to treat patients with breast cancer.

Results

It has recently been reported that epigenetic processes such as DNA methylation and histone modification, as well as microRNAs (miRNAs), have potently contributed to the pathophysiology, diagnosis, and treatment of breast cancer. These observations have persuaded researchers to move their therapeutic approaches beyond the genetic framework toward the epigenetic concept.

Conclusion

Herein we discuss the molecular and epigenetic mechanisms underlying breast cancer progression and resistance as well as various aspects of epigenetic-based therapies as monotherapy and combined with immunotherapy.

Prognostic and Predictive Effects of Tumor and Plasma miR-200c-3p in Locally Advanced and Metastatic Breast Cancer

While the role of miR-200c in cancer progression has been established, its expression and prognostic role in breast cancer is not completely understood. The predictive role of miR-200c in response to chemotherapy has also been suggested by some studies, but only limited clinical evidence is available. The purpose of this study was to investigate miR-200c-3p in the plasma and primary tumor of BC patients. The study design included two cohorts involving women with locally advanced (LABC) and metastatic breast cancer. Tumor and plasma samples were obtained before and after treatment. We found that miR-200c-3p was significantly higher in the plasma of BC patients compared with the controls. No correlation of age with plasma miR-200c-3p was found for controls or for BC patients. MiR-200c-3p tumor expression was also associated with poor overall survival in LABC patients treated with neoadjuvant chemotherapy, independently of pathological complete response or clinical stage. Our findings suggest that plasmatic miR-200c-3p levels could be useful for BC staging, while the tumor expression of miR-200c-3p might provide further prognostic information beyond residual disease in BC treated with neoadjuvant chemotherapy.

Elevated Expression of miR-200c/141 in MDA-MB-231 Cells Suppresses MXRA8 Levels and Impairs Breast Cancer Growth and Metastasis In Vivo

Breast cancer cells with mesenchymal characteristics, particularly the claudin-low subtype, express extremely low levels of miR-200s. Therefore, this study examined the functional impact of restoring miR-200 expression in a human claudin-low breast cancer cell line MDA-MB-231. MDA-MB-231 cells were stably transfected with a control vector (MDA-231EV) or the miR-200c/141 cluster (MDA-231c141). Injection of MDA-231c141 cells into the 4th mammary gland of NCG mice produced tumors that developed significantly slower than tumors produced by MDA-231EV cells. Spontaneous metastasis to the lungs was also significantly reduced in MDA-231c141 cells compared to MDA-231EV cells. RNA sequencing of MDA-231EV and MDA-231c141 tumors identified genes including MXRA8 as being downregulated in the MDA-231c141 tumors. MXRA8 was further investigated as elevated levels of MXRA8 were associated with reduced distant metastasis free survival in breast cancer patients. Quantitative RT-PCR and Western blotting confirmed that MXRA8 expression was significantly higher in mammary tumors induced by MDA-231EV cells compared to those induced by MDA-231c141 cells. In addition, MXRA8 protein was present at high levels in metastatic tumor cells found in the lungs. This is the first study to implicate MXRA8 in human breast cancer, and our data suggests that miR-200s inhibit growth and metastasis of claudin-low mammary tumor cells in vivo through downregulating MXRA8 expression.

Non-Exosomal and Exosome-Derived miRNAs as Promising Biomarkers in Canine Mammary Cancer

Canine mammary cancer (CMC), similar to human breast cancer (HBC) in many aspects, is the most common neoplasm associated with significant mortality in female dogs. Due to the limited therapy options, biomarkers are highly desirable for early clinical diagnosis or cancer progression monitoring. Since the discovery of microRNAs (miRNAs or miRs) as post-transcriptional gene regulators, they have become attractive biomarkers in oncological research. Except for intracellular miRNAs and cell-free miRNAs, exosome-derived miRNAs (exomiRs) have drawn much attention in recent years as biomarkers for cancer detection. Analysis of exosomes represents a non-invasive, pain-free, time- and money-saving alternative to conventional tissue biopsy. The purpose of this review is to provide a summary of miRNAs that come from non-exosomal sources (canine mammary tumor, mammary tumor cell lines or canine blood serum) and from exosomes as promising biomarkers of CMC based on the current literature. As is discussed, some of the miRNAs postulated as diagnostic or prognostic biomarkers in CMC were also altered in HBC (such as miR-21, miR-29b, miR-141, miR-429, miR-200c, miR-497, miR-210, miR-96, miR-18a, miR19b, miR-20b, miR-93, miR-101, miR-105a, miR-130a, miR-200c, miR-340, miR-486), which may be considered as potential disease-specific biomarkers in both CMC and HBC.

Evidence of antagonistic predictive effects of miRNAs in breast cancer cohorts through data-driven networks

Non-coding micro RNAs (miRNAs) dysregulation seems to play an important role in the pathways involved in breast cancer occurrence and progression. In different studies, opposite functions may be assigned to the same miRNA, either promoting the disease or protecting from it. Our research tackles the following issues: (i) why aren’t there any concordant findings in many research studies regarding the role of miRNAs in the progression of breast cancer? (ii) could a miRNA have either an activating effect or an inhibiting one in cancer progression according to the other miRNAs with which it interacts? For this purpose, we analyse the AHUS dataset made available on the ArrayExpress platform by Haakensen et al. The breast tissue specimens were collected over 7 years between 2003 and 2009. miRNA-expression profiling was obtained for 55 invasive carcinomas and 70 normal breast tissue samples. Our statistical analysis is based on a recently developed model and feature selection technique which, instead of selecting a single model (i.e. a unique combination of miRNAs), delivers a set of models with equivalent predictive capabilities that allows to interpret and visualize the interaction of these features. As a result, we discover a set of 112 indistinguishable models (in a predictive sense) each with 4 or 5 miRNAs. Within this set, by comparing the model coefficients, we are able to identify three classes of miRNA: (i) oncogenic miRNAs; (ii) protective miRNAs; (iii) undefined miRNAs which can play both an oncogenic and a protective role according to the network with which they interact. These results shed new light on the biological action of miRNAs in breast cancer and may contribute to explain why, in some cases, different studies attribute opposite functions to the same miRNA.

Involvement of microRNA modifications in anticancer effects of major polyphenols from green tea, coffee, wine, and curry

Epidemiological studies have shown that consumption of green tea, coffee, wine, and curry may contribute to a reduced risk of various cancers. However, there are some cancer site-specific differences in their effects; for example, the consumption of tea or wine may reduce bladder cancer risk, whereas coffee consumption may increase the risk. Animal and cell-based experiments have been used to elucidate the anticancer mechanisms of these compounds, with reactive oxygen species (ROS)-based mechanisms emerging as likely candidates. Chlorogenic acid (CGA), curcumin (CUR), epigallocatechin gallate (EGCG), and resveratrol (RSV) can act as antioxidants that activate AMP-activated protein kinase (AMPK) to downregulate ROS, and as prooxidants to generate ROS, leading to the downregulation of NF-κB. Polyphenols can modulate miRNA (miR) expression, with these dietary polyphenols shown to downregulate tumor-promoting miR-21. CUR, EGCG, and RSV can upregulate tumor-suppressing miR-16, 34a, 145, and 200c, but downregulate tumor-promoting miR-25a. CGA, EGCG, and RSV downregulate tumor-suppressing miR-20a, 93, and 106b. The effects of miRs may combine with ROS-mediated pathways, enhancing the anticancer effects of these polyphenols. More precise analysis is needed to determine how the different modulations of miRs by polyphenols relate to the cancer site-specific differences found in epidemiological studies related to the consumption of foods containing these polyphenols.

The regulatory role of pivotal microRNAs in the AKT signaling pathway in breast cancer

Breast cancer is the most prevalent type of cancer among women, and it remains the main challenge despite improved treatments. MicroRNAs (miRNAs) are a small non-coding family of RNAs that play an indispensable role in regulating major physiological processes, including differentiation, proliferation, invasion, migration, cell cycle regulation, stem cell maintenance, apoptosis, and organ development. The dysregulation of these tiny molecules is associated with various human malignancies. More than 50% of these non-coding RNA sequences estimated have been placed on genomic regions or fragile sites linked to cancer. Following the discovery of the first signatures of specific miRNA in breast cancer, numerous researches focused on involving these tiny RNAs in breast cancer physiopathology as a new therapeutic approach or as reliable prognostic biomarkers. In the current review, we focus on recent findings related to the involvement of miRNAs in breast cancer via the AKT signaling pathway and the related clinical implications.

MicroRNAs and Extracellular Vesicles as Distinctive Biomarkers of Precocious and Advanced Stages of Breast Cancer Brain Metastases Development

Triple negative breast cancer presents higher mortality and poorer survival rates than other breast cancer (BC) types, due to the proneness to brain metastases formation, which are usually diagnosed at advanced stages. Therefore, the discovery of BC brain metastases (BCBM) biomarkers appears pivotal for a timely intervention. With this work, we aimed to disclose microRNAs (miRNAs) and extracellular vesicles (EVs) in the circulation as biomarkers of BCBM formation. Using a BCBM animal model, we analyzed EVs in plasma by nanoparticle tracking analysis and ascertained their blood-brain barrier (BBB) origin by flow cytometry. We further evaluated circulating miRNAs by RT-qPCR and their brain expression by in situ hybridization. In parallel, a cellular model of BCBM formation, combining triple negative BC cells and BBB endothelial cells, was used to differentiate the origin of biomarkers. Established metastases were associated with an increased content of circulating EVs, particularly of BBB origin. Interestingly, deregulated miRNAs in the circulation were observed prior to BCBM detection, and their brain origin was suggested by matching alterations in brain parenchyma. In vitro studies indicated that miR-194-5p and miR-205-5p are expressed and released by BC cells, endothelial cells and during their interaction. These results highlight miRNAs and EVs as biomarkers of BCBM in early and advanced stages, respectively.

MicroRNA-200c Prevents Progress of Cutaneous Squamous Cell Carcinoma by Targeting Tyrosine-Protein Kinase Fyn (FYN)

Cutaneous squamous cell carcinoma (cSCC), a malignant skin tumor, begins in the epidermis and the keratinocytes of the skin appendages. However, the cause remains unclear. MicroRNA-200c (miR-200c), a key modulator of epithelial-to-mesenchymal transition (EMT), has been reported to act as an anticancer gene in a variety of cancers. However, its role and partial mechanism in cSCC remain undetermined. The results of this study showed depleted levels of miR-200c in cSCC tissues. Its suppressive effects on cell proliferation, and motility, as well as its apoptosis-promoting effect, were observed in the A-431 cells. Additionally, immunofluorescence and qRT-PCR assays revealed that FYN acted as a direct target of miR-200c, and FYN knockdown exerted had similar impact as that of miR-200c overexpression, including increased cellular apoptosis and decreased cellular growth. These results emphasized the onco-suppressive nature of miR-200c, which was evident based on its interaction with FYN in cSCC. This finding could have potential benefits in developing cSCC therapy.

miR-34a and miR-200c Have an Additive Tumor-Suppressive Effect on Breast Cancer Cells and Patient Prognosis

Breast cancer is the most common women's malignancy in the world and, for subgroups of patients, treatment outcomes remain poor. Thus, more effective therapeutic strategies are urgently needed. MicroRNAs (miRNAs) have emerged as promising therapeutic tools and targets, as they play significant roles in regulating key cellular processes by suppressing gene expression. However, additive opportunities involving miRNAs have been underexplored. For example, both miR-34a and miR-200c individually suppress the development of different types of cancer, but the cellular effects of their combined actions remain unknown. Here, we show that miR-34a and miR-200c levels are reduced in breast tumors compared to adjacent normal tissues and that this additively predicts poor patient survival. In addition, in cell lines, miR-34a and miR-200c additively induce apoptosis and cell cycle arrest, while also inhibiting proliferation, invasion, migration, stemness and epithelial-to-mesenchymal transition (EMT). Mechanistically, both miRNA-34a and miR-200c directly target HIF1-α and subsequently downregulate VEGFR, MMP9 and CXCR4, although combined miRNA-34a and miR-200c delivery suppresses mouse xenograft tumor development as effectively as individual delivery. We establish a model, supported by in vitro and clinical data, which collectively suggest that the co-delivery of miR-34a and miR-200c represents a promising novel therapeutic strategy for breast cancer patients.

Portrait of Cancer Stem Cells on Colorectal Cancer: Molecular Biomarkers, Signaling Pathways and miRNAome

Colorectal cancer (CRC) is a leading cause of cancer death worldwide, and about 20% is metastatic at diagnosis and untreatable. Increasing evidence suggests that the heterogeneous nature of CRC is related to colorectal cancer stem cells (CCSCs), a small cells population with stemness behaviors and responsible for tumor progression, recurrence, and therapy resistance. Growing knowledge of stem cells (SCs) biology has rapidly improved uncovering the molecular mechanisms and possible crosstalk/feedback loops between signaling pathways that directly influence intestinal homeostasis and tumorigenesis. The generation of CCSCs is probably connected to genetic changes in members of signaling pathways, which control self-renewal and pluripotency in SCs and then establish function and phenotype of CCSCs. Particularly, various deregulated CCSC-related miRNAs have been reported to modulate stemness features, controlling CCSCs functions such as regulation of cell cycle genes expression, epithelial-mesenchymal transition, metastasization, and drug-resistance mechanisms. Primarily, CCSC-related miRNAs work by regulating mainly signal pathways known to be involved in CCSCs biology. This review intends to summarize the epigenetic findings linked to miRNAome in the maintenance and regulation of CCSCs, including their relationships with different signaling pathways, which should help to identify specific diagnostic, prognostic, and predictive biomarkers for CRC, but also develop innovative CCSCs-targeted therapies.

Combined analysis of miR-200 family and its significance for breast cancer

While the molecular functions of miR-200 family have been deeply investigated, a role for these miRNAs as breast cancer biomarkers remains largely unexplored. In the attempt to clarify this, we profiled the miR-200 family members expression in a large cohort of breast cancer cases with a long follow-up (H-CSS cohort) and in TCGA-BRCA cohort. Overall, miR-200 family was found upregulated in breast tumors with respect to normal breast tissues while downregulated in more aggressive breast cancer molecular subtypes (i.e. Luminal B, HER2 and triple negative), consistently with their function as repressors of the epithelial-to-mesenchymal transition (EMT). In particular miR-141-3p was found differentially expressed in breast cancer molecular subtypes in both H-CSS and TCGA-BRCA cohorts, and the combined analysis of all miR-200 family members demonstrated a slight predictive accuracy on H-CSS cancer specific survival at 12 years (survival c-statistic: 0.646; 95%CI 0.538–0.754).

The effects of mutant Ras proteins on the cell signalome

The genetic alterations in cancer cells are tightly linked to signaling pathway dysregulation. Ras is a key molecule that controls several tumorigenesis-related processes, and mutations in RAS genes often lead to unbiased intensification of signaling networks that fuel cancer progression. In this article, we review recent studies that describe mutant Ras-regulated signaling routes and their cross-talk. In addition to the two main Ras-driven signaling pathways, i.e., the RAF/MEK/ERK and PI3K/AKT/mTOR pathways, we have also collected emerging data showing the importance of Ras in other signaling pathways, including the RAC/PAK, RalGDS/Ral, and PKC/PLC signaling pathways. Moreover, microRNA-regulated Ras-associated signaling pathways are also discussed to highlight the importance of Ras regulation in cancer. Finally, emerging data show that the signal alterations in specific cell types, such as cancer stem cells, could promote cancer development. Therefore, we also cover the up-to-date findings related to Ras-regulated signal transduction in cancer stem cells.

Bioinformatic screening for candidate biomarkers and their prognostic values in endometrial cancer

BACKGROUND

Endometrial cancer is a common gynecological cancer with annually increasing incidence worldwide. However, the biomarkers that provide prognosis and progression for this disease remain elusive.

RESULTS

Two eligible human endometrial cancer datasets (GSE17025 and GSE25405) were selected for the study. A total of 520 differentially expressed mRNAs and 30 differentially expressed miRNAs were identified. These mRNAs were mainly enriched in cell cycle, skeletal system development, vasculature development, oocyte maturation, and oocyte meiosis signalling pathways. A total of 160 pairs of differentially expressed miRNAs and mRNAs, including 22 differentially expressed miRNAs and 71 overlapping differentially expressed mRNAs, were validated in endometrial cancer samples using starBase v2.0 project. The prognosis analysis revealed that Cyclin E1 (CCNE1, one of the 82 hub genes, which correlated with hsa-miR-195 and hsa-miR-424) was significantly linked to a worse overall survival in endometrial cancer patients.

CONCLUSIONS

The hub genes and differentially expressed miRNAs identified in this study might be used as prognostic biomarkers for endometrial cancer and molecular targets for its treatment.

MicroRNAs in breast cancer: New maestros defining the melody

MicroRNAs, short non-coding single-stranded RNAs, are important regulators and gatekeepers of the coding genes in the human genome. MicroRNAs are highly conserved among species and expressed in different tissues and cell types. They are involved in almost all the biological processes as apoptosis, proliferation, cell cycle arrest and differentiation. Playing all these roles, it is not surprising that the deregulation of the microRNA profile causes a number of diseases including cancer. Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Different microRNAs were shown to be up or down regulated in breast cancer. MicroRNAs can function as oncogenes or tumor suppressors according to their targets. In this review, the most common microRNAs implicated in breast cancer are fully illustrated with their targets. Besides, the review highlights the effect of exosomal microRNA on breast cancer and the effect of microRNAs on drug and therapies resistance as well as the miRNA-based therapeutic strategies used until today.

Role of regulatory miRNAs of the PI3K/AKT signaling pathway in the pathogenesis of breast cancer

Breast cancer is one of the most common tumors in women. Current data indicate that the overexpression of some microRNAs (miRNAs) is associated with breast cancer, in relation to stage, tumor size and potential for metastasis. Some studies have reported that miRNAs have critical roles in cellular processes implicated in breast cancer cell growth, migration and metastasis by targeting the PI3K/AKT oncogenic signaling pathway. Therefore, identifying novel regulatory miRNAs for this oncogenic pathway and discovery of their related target genes may represent a promising therapeutic approach for breast cancer therapy. This review highlights the recent findings about the potential role of PI3K/AKT signaling regulatory miRNAs in breast cancer tumorigenesis.

Down-Regulation of miR-200c and Up-Regulation of miR-30c Target both Stemness and Metastasis Genes in Breast Cancer

OBJECTIVE

microRNAs (miRNAs) play important role in progression of tumorigenesis. They can target self-renewal and epithelial-mesenchymal transition (EMT) abilities in tumor cells, especially in cancer stem cells (CSCs). The objective of this study was to implement data mining to identify important miRNAs for targeting both self-renewal and EMT. We also aimed to evaluate these factors in mammospheres as model of breast cancer stem cells (BCSCs) and metastatic tumor tissues.

MATERIALS AND METHODS

In this experimental study, mammospheres were derived from MCF-7 cells and characterized for the CSCs properties. Then expression pattern of the selected miRNAs in spheroids were evaluated, using the breast tumor cells obtained from seven patients. Correlation of miRNAs with self-renewal and EMT candidate genes were assessed in mammospheres and metastatic tumors.

RESULTS

The results showed that mammospheres represented more colonogenic and spheroid formation potential than MCF-7 cells (P<0.05). Additionally, they had enhanced migration and invasive capabilities. Our computational analyses determined that miR-200c and miR-30c could be candidates for targeting both stemness and EMT pathways. Expression level of miR-200c was reduced, while miR-30c expression level was enhanced in mammospheres, similar to the breast tumor tissues isolated from three patients with grade II/III who received neo-adjuvant treatment. Expression level of putative stem cell markers (OCT4, SOX2, c-MYC) and EMT-related genes (SNAIL1, CDH2, TWIST1/2) were also significantly increased in mammospheres and three indicated patients (P<0.05).

CONCLUSION

Simultaneous down-regulation and up-regulation of respectively miR-200c and miR-30c might be signature of BCSC enrichment in patients post neo-adjuvant therapy. Therefore, targeting both miR-200c and miR-30c could be useful for developing new therapeutic approaches, against BCSCs.

MicroRNAs in breast cancer: Roles, functions, and mechanism of actions

Breast cancer is one of the most lethal malignancies in women in the world. Various factors are involved in the development and promotion of the malignancy; most of them involve changes in the expression of certain genes, such as microRNAs (miRNAs). MiRNAs can regulate signaling pathways negatively or positively, thereby affecting tumorigenesis and various aspects of cancer progression, particularly breast cancer. Besides, accumulating data demonstrated that miRNAs are a novel tool for prognosis and diagnosis of breast cancer patients. Herein, we will review the roles of these RNA molecules in several important signaling pathways, such as transforming growth factor, Wnt, Notch, nuclear factor-κ B, phosphoinositide-3-kinase/Akt, and extracellular-signal-regulated kinase/mitogen activated protein kinase signaling pathways in breast cancer.

Targeting miRNAs by histone deacetylase inhibitors (HDACi): Rationalizing epigenetics-based therapies for breast cancer

MicroRNAs (miRNAs) belong to a group of short RNA molecules of ~22 nucleotides that play a significant role in the regulation of gene expression through post-transcriptional regulatory mechanisms. They can directly interact with their target mRNA molecules and induce target gene silencing. Many investigations over the past decade have revealed the involvement of different miRNAs in essential biological events. The expression of a considerable number of miRNAs is tightly regulated through epigenetic events such as histone modifications and DNA methylation. Notably, irregularities in these epigenetic events are associated with aberrant expression of miRNAs in a range of diseases including cancer. Impaired epigenetic events associated with aberrant expression of miRNAs can be pharmacologically modified using chromatin modifying drugs. Numerous pre-clinical and clinical data demonstrate that histone deacetylase inhibitors (HDACi) can re-establish the expression of aberrantly expressed miRNAs in a range of cancer types, rationalizing miRNAs as potential drug targets. This review highlights evidence from investigations assessing the effects of different classes of HDACi on miRNA expression in breast cancer (BC).

miR-200c suppresses stemness and increases cellular sensitivity to trastuzumab in HER2+ breast cancer

Resistance to trastuzumab remains a major obstacle in HER2‐overexpressing breast cancer treatment. miR‐200c is important for many functions in cancer stem cells (CSCs), including tumour recurrence, metastasis and resistance. We hypothesized that miR‐200c contributes to trastuzumab resistance and stemness maintenance in HER2‐overexpressing breast cancer. In this study, we used HER2‐positive SKBR3, HER2‐negative MCF‐7, and their CD44⁺CD24⁻ phenotype mammospheres SKBR3‐S and MCF‐7‐S to verify. Our results demonstrated that miR‐200c was weakly expressed in breast cancer cell lines and cell line stem cells. Overexpression of miR‐200c resulted in a significant reduction in the number of tumour spheres formed and the population of CD44⁺CD24⁻ phenotype mammospheres in SKBR3‐S. Combining miR‐200c with trastuzumab can significantly reduce proliferation and increase apoptosis of SKBR3 and SKBR3‐S. Overexpression of miR‐200c also eliminated its downstream target genes. These genes were highly expressed and positively related in breast cancer patients. Overexpression of miR‐200c also improved the malignant progression of SKBR3‐S and SKBR3 in vivo. miR‐200c plays an important role in the maintenance of the CSC‐like phenotype and increases drug sensitivity to trastuzumab in HER2+ cells and stem cells.

Exosomal miR-200 family as serum biomarkers for early detection and prognostic prediction of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a common and lethal disease but lacks of efficient biomarkers for early detection. A previous study using CCA cell lines showed a CCA-specific exosomal microRNA profile. We aimed to verify the results in CCA patients and evaluate the potential roles of these exosomal microRNAs as serum biomarkers. Peripheral blood samples were collected from 36 CCA patients and 12 healthy controls. Twenty exosomal microRNAs were compared between CCA and control group. The diagnostic value was assessed using area under receiver operating characteristic curve (AUC). Out of 20 exosomal microRNAs, 5 significantly differentially expressed between CCA and control group. Four microRNAs in miR-200 family (miR-141-3p, miR-200a-3p, miR-200b-3p, and miR-200c-3p) showed higher AUCs than CA19-9 (0.78). MiR-200c-3p presented the best diagnostic ability with the AUC of 0.93. Furthermore, miR-200a/c-3p was positively correlated with tumor stage (P < 0.05). Patients with advance tumor stage (III-IV) showed significantly higher serum exosomal miR-200a/c-3p levels than those with early stage (I-II) (P < 0.05). In conclusion, serum exosomal miR-200 family, particularly miR-200c-3p, could be efficient biomarkers for CCA. The serum levels of exosomal miR-200a/c-3p also represented the rate of CCA progression.

Synthesis of Nano-Paramagnetic Oleuropein to Induce KRAS Over-Expression: A New Mechanism to Inhibit AGS Cancer Cells

Background and objectives: Human gastric adenocarcinoma (AGS) is one of the most common malignant cancers worldwide. The present study aimed to transfer oleuropein into cancer cells using synthetic paramagnetic nanoparticles and study their effect on the AGS (ATCC^® CRL1739™) cell line. Materials and Methods: Paramagnetic nano-oleuropein was synthesized using four-stage co-precipitation by developing NH-connected bridges and was evaluated by EDS, SEM and FTIR methods. Different concentrations of magnetic oleuropein (0, 0.15, 0.45, 1.37, 4.12, 12.35, 37.04, 111.11, 333.33, 1000 µg/mL) were used to treat the AGS cell line in a completely randomized design using a statistical framework with three replicates. The relative expression rate of miR-200 and KRAS oncogenes was evaluated using real-time PCR. The inhibition rate of the AGS cells was assessed using the MTT test at 24, 48 and 72 h intervals. Results: The results showed that there was a significant difference between the inhibition rates of magnetic nano-oleuropein at IC50-24h (23.6 µg/mL), IC50-48h (15.2 µg/mL) and IC50-72h (9.2 µg/mL). Real-time PCR indicated that the relative expression of KRAS and miR-200 genes was highest at IC50 at these intervals. Conclusions: Magnetic nano-oleuropein can be subjected to objective testing and clinical evaluations as a natural antioxidant to prevent and treat gastric adenocarcinoma.

The Significance Role of microRNA-200c as a Prognostic Factor in Various Human Solid Malignant Neoplasms: A Meta-Analysis

Objective: The aim of this study was to conduct a meta-analysis of 49 relevant studies to evaluate the prognostic value of miRNA-200c in various human malignant neoplasms.

Methods: All relevant studies were identified by searching PubMed, Embase and Web of Science until August 15^st, 2018. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of miRNA-200c for overall survival (OS) and progression-free survival (PFS)/recurrence-free survival (RFS)/disease-free survival (DFS) were calculated to investigate such associations.

Results: Overall, 49 eligible studies were included in this meta-analysis. Our results showed that high expression of miRNA-200c was significantly correlated with a poor OS in cancer (pooled HR = 1.32, 95% CI: 1.06-1.65), but was not significantly correlated with PFS/RFS/DFS in cancer (pooled HR=1.05, 95% CI: 0.84-1.23). In our subgroup analysis, high miRNA-200c expression predicted a significantly worse OS (pooled HR = 1.50, 95% CI: 1.12-2.01) only in Caucasians. Moreover, high miRNA-200c expression even showed significantly poor OS (pooled HR = 1.88, 95% CI: 1.39-2.54) in blood samples. In addition, a significantly unfavorable OS (pooled HR = 2.69, 95% CI: 1.49-4.85) and (pooled HR = 2.66, 95% CI: 1.07-6.59) associated with up-regulated miRNA-200c expression were observed in breast cancer and endometrial cancer, respectively. Besides, high miRNA-200c expression also showed significantly poor PFS/RFS/DFS (pooled HR=1.66, 95% CI: 1.03-2.67) in breast cancer.

Conclusions: Our findings indicated that high miRNA-200c expression was a promising biomarker for patient survival and disease progression in malignant tumors, especially in breast cancer and endometrial cancer. Considering the insufficient evidence, further large-scale researches and clinical studies were needed to verify these results.

Role of micro-RNAs in breast cancer surgery

BACKGROUND

The management of breast cancer has changed dramatically in the molecular era. Micro-RNAs can contribute to multiple facets of cancer surgery.

METHODS

This narrative review, based on years of research on the role of micro-RNAs, focused on the potential of these small, robust RNAs to influence all aspects of breast cancer surgery.

RESULTS

Micro-RNAs have a potential role as biomarkers in the diagnosis, prognosis and evaluation of response to therapy in breast cancer. They may also contribute to future therapeutic strategies.

CONCLUSION

The molecular era has changed understanding of cancer. Micro-RNAs have the potential for use in personalized cancer strategies.

Phosphodiesterase 7B/microRNA-200c relationship regulates triple-negative breast cancer cell growth

Members of microRNA-200 (miRNA-200) family play a regulatory role in epithelial to mesenchymal transition (EMT) by suppressing Zeb1 and Zeb2 expression. Consistent with its role in suppressing EMT, Hsa-miR-200c-3p (miR-200c), a member of miR-200 family is poorly expressed in mesenchymal-like triple negative breast cancer (TNBC) cells and ectopic miR-200c expression suppresses cell migration. In this manuscript, we demonstrated that miR-200c potently inhibited TNBC cell growth and tumor development in a mechanism distinct from its ability to downregulate Zeb1 and Zeb2 expression because silencing them only marginally affected TNBC cell growth. We identified phosphodiesterase 7B (PDE7B) as a bona fide miR-200c target. Importantly, miR-200c-led inhibition in cell growth and tumor development was prevented by forcing PDE7B transgene expression while knockdown of PDE7B effectively inhibited cell growth. These results suggest that miR-200c inhibits cell growth by targeting PDE7B mRNA. To elucidate mechanism underlying miR-200c/PDE7B regulation of TNBC cell growth, we showed that cAMP concentration was lower in TNBC cells compared to estrogen receptor-positive (ER+) cells and that both miR-200c and PDE7B siRNAs were able to increase cAMP concentration in TNBC cells. High level of cellular cAMP has been shown to induce cell cycle arrest and apoptosis in TNBC cells. Our observation that ectopic expression of miR-200c triggered apoptosis indicates that it does so by elevating level of cellular cAMP. Analysis of breast tumor gene expression datasets revealed an inverse association between miR-200c and PDE7B expression. Especially, both low miR-200c and high PDE7B expression were correlated with poor survival of breast cancer patients. Our study supports a critical role of miR-200c/PDE7B relationship in TNBC tumorigenesis.

Pax-5 Inhibits NF-κB Activity in Breast Cancer Cells Through IKKε and miRNA-155 Effectors

Pax-5, an essential transcription factor in B cell development, is aberrantly expressed in various B cell cancer lesions and solid tumors such as breast carcinoma. We have recently shown that Pax-5 regulates NF-κB activity which lead to the modulation of breast cancer phenotypic features (EMT-MET). NF-κB is known as a central mediator in inflammation, stress response as well as being a gatekeeper of pro-tumorigenic activity. However, little is known as to how Pax-5 affects this modulation. We thus turned our attention to microRNAs as potential regulatory effectors. In this study, we set out to elucidate the regulatory network between differential Pax-5 expression and NF-κB activity which dictate breast cancer malignancy. Through next-generation sequencing (NGS) of breast cancer cells conditionally expressing Pax-5, we profile significantly upregulated microRNAs; including microRNA-155, a known regulator of pathological processes and suppressor of malignant growth. Through the conditional expression of microRNA-155 in breast cancer models, we identify and validate IKKε (IKBKE) as a downstream target and an essential effector of Pax-5-mediated suppression of NF-κB signaling. Using rescue experiments, we also confirm that Pax-5 modulates NF-κB activity via IKKε downregulation. Interestingly, we also show that microRNA-155, in turn, supresses Pax-5 expression, indicative of an auto-regulatory feedback loop. Altogether, we demonstrate that Pax-5 inhibits NF-κB signalling through the regulation of microRNA-155 and its downstream target IKKε. The elucidation of this signaling network is relevant as Pax-5 and NF-κB are potent transcriptional regulators of breast cancer aggressivity. In addition, IKKε is relevant oncogene aberrantly expressed in 30% of breast carcinomas. Further insight into the regulatory pathways of breast cancer progression will eventually identify strategic therapeutic and prognostic targets to improve cancer patient outcome.

Effects of miRNAs on functions of breast cancer stem cells and treatment of breast cancer

Breast cancer is one of the most common malignancies for women, which accounts for 30% of all female malignancies. The formation of breast cancer stem cells (BCSCs) is attributed to the acquisition of stemness of tumor cells. With self-renewal potential, these stem cells are insensitive to either radiotherapy or chemotherapy but are significant in regulating tumor behaviors and drug resistance. MicroRNA (miRNA) is a kind of noncoding small RNA for negatively regulating gene expressions. Research findings suggest that many miRNAs specifically regulate the expression of target genes and signal pathways of BCSCs. They play an important role in self-renewal, growth, and metastasis of breast cancer cells as potential targets for treating breast cancer. These signal pathways include phosphatase and tensin homolog deleted on chromosome 10-phosphatidylinositol 3-kinase/Akt, Wnt/β-catenin, Notch, and so on. This paper reviews the progress of research about miRNAs in self-renewal, metastasis, epithelial-mesenchymal transition and metastasis, mediation of resistance to chemotherapies, and treatment of breast cancer.

Circulating microRNAs in the early prediction of disease recurrence in primary breast cancer

Background

In primary breast cancer metastases frequently arise from a state of dormancy that may persist for extended periods of time. We investigated the efficacy of plasma micro-RNA (miR)-21, miR-23b, miR-190, miR-200b and miR-200c, related to dormancy and metastasis, to predict the outcome of patients with early breast cancer.

Methods

miRNAs were evaluated by RT-qPCR in plasma obtained before adjuvant chemotherapy. miRNA expression, classified as high or low according to median values, correlated with relapse and survival. Receiver operating characteristic (ROC) curves were constructed to determine miRNA sensitivity and specificity.

Results

miR-21 (p < 0.001), miR-23b (p = 0.028) and miR-200c (p < 0.001) expression were higher and miR-190 was lower (p = 0.013) in relapsed (n = 49), compared to non-relapsed patients (n = 84). Interestingly, miR-190 was lower (p = 0.0032) in patients with early relapse (at < 3 years; n = 23) compared to those without early relapse (n = 110). On the other hand, miR-21 and miR-200c were higher (p = 0.015 and p < 0.001, respectively) in patients with late relapse (relapse at ≥ 5 years; n = 20) as compared to non-relapsed patients. High miR-200c was associated with shorter disease-free survival (DFS) (p = 0.005) and high miR-21 with both shorter DFS and overall survival (OS) (p < 0.001 and p = 0.033, respectively) compared to low expression. ROC curve analysis revealed that miR-21, miR-23b, miR-190 and miR-200c discriminated relapsed from non-relapsed patients. A combination of of miR-21, miR-23b and miR-190 showed higher sensitivity and specificity in ROC analyses compared to each miRNA alone; accuracy was further improved by adding lymph node infiltration and tumor grade to the panel of three miRs (AUC 0.873). Furthermore, the combination of miR-200c, lymph node infiltration, tumor grade and estrogen receptor predicted late relapse (AUC 0.890).

Conclusions

Circulating miRNAs are differentially expressed among relapsed and non-relapsed patients with early breast cancer and predict recurrence many years before its clinical detection. Our results suggest that miRNAs represent potential circulating biomarkers in early breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1001-3) contains supplementary material, which is available to authorized users.

Zerumbone inhibits epithelial-mesenchymal transition and cancer stem cells properties by inhibiting the β-catenin pathway through miR-200c

Colorectal cancer (CRC) is one of the most lethal and rampant human malignancies in the world. Zerumbone, a sesquiterpene isolated from subtropical ginger, has been found to exhibit an antitumor effect in various cancer types. However, the effect of Zerumbone on the biological properties of CRC, including epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) has not been fully elucidated. Here, we investigated the inhibitory action of Zerumbone on the EMT process, CSC markers, and the β-catenin signaling pathway in the presence or absence of miR-200c. The effect of Zerumbone on HCT-116 and SW-48 cells viability was examined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. The effects of Zerumbone on EMT-related genes, CSCs markers, cell migration, invasion, sphere-forming, and β-catenin signaling pathway were explored. To evaluate the role of miR-200c in anticancer effects by Zerumbone, miR-200c was downregulated by LNA-anti-miR-200c. Zerumbone significantly inhibited cell viability, migration, invasion, and sphere-forming potential in HCT-116 and SW-48 cell lines. Zerumbone significantly suppressed the EMT and CSC properties as well as downregulated the β-catenin. Silencing of miR200c reduced the inhibitory effects of Zerumbone on EMT and CSCs in CRC cells. These data indicated that Zerumbone may be a promising candidate for reducing the risk of CRC progression by suppressing the β-catenin pathway via miR-200c.

DCLK1 plays an important role in colorectal cancer tumorgenesis through the regulation of miR-200c

Doublecortin-like kinase 1 (DCLK1) is a protein kinase that is known as a specific cancer stem cell (CSC) marker in colorectal cancer (CRC). Deregulation of DCLK1 expression has been reported in various cancers. We measured the protein expression of DCLK1 in 38 CRC and normal colon samples by immunohistochemistry (IHC). HCT-116 and SW-48 cells were transfected with DCLK1 siRNA and analyzed for expression of DCLK1 and miR-200c. The effects of DCLK1 knockdown on cell migration, invasion, sphere-forming, and apoptosis were explored. It was found that DCLK1 protein expression levels were significantly higher in CRC tissue than in normal colon specimens. Silencing of DCLK1 significantly inhibited cell migration, invasion, and sphere-forming potential; it also induced apoptosis as well as increased expression of miR-200c. Furthermore, silencing of miR-200c significantly up-regulated DCLK1 expression. Overall, our data demonstrated that DCLK1 plays an important role in cancer progression and is involved in the regulation of miR-200c expression.

miR-422a inhibits osteosarcoma proliferation by targeting BCL2L2 and KRAS

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. However, the underlying mechanism of osteosarcoma carcinogenesis and progression remains unknown. In the present study, we evaluated the expression profile of miRNAs in osteosarcoma tissues and the adjacent normal tissues. We found that the expression of miR-422a was down-regulated in osteosarcoma tissues and cell lines. In addition, we observed significantly elevated levels of repressive H3K9me3 and H3K27me3 and decreased active H3K4me3 on the promote region of miR-422a in osteosarcoma cells and clinical samples. Furthermore, up-regulation of miR-422a exhibited both in vitro and in vivo anti-tumor effects by inhibiting osteosarcoma cell growth and inducing apoptosis and cell cycle arrest. We also found that miR-422a targeted BCL2L2 and KRAS and negatively regulated their protein expression. Furthermore, restoration of miR-422a and knockdown of BCL2L2 and KRAS promoted apoptosis and induce cell cycle arrest in osteosarcoma cells. Taken together, the present study demonstrates that miR-422a may serve as a tumor suppressor in osteosarcoma via inhibiting BCL2L2 and KRAS translation both in vitro and in vivo. Therefore, miR-422a could be developed as a novel therapeutic target in osteosarcoma.

Downregulation of hsa_circ_0011946 suppresses the migration and invasion of the breast cancer cell line MCF-7 by targeting RFC3

Introduction

Although some circRNAs have been found to regulate the progression of malignancies, their functions and coupled molecular mechanisms are still unclear. In our study, we sought to assess the underlying molecular mechanisms of circRNAs in breast cancer and therefore explored the differentially expressed circRNAs and co-expression networks, followed by in vitro experiments.

Materials and methods

High-throughput RNA sequencing was performed to obtain an unbiased profile of circRNA expression. CircRNA-miRNA-mRNA co-expression networks were predicted, and sequence analyses were carried out. The MTT, transwell migration and invasion assay was conducted in Michigan Cancer Foundation-7 cells that had been transfected with si-circRNA and si-negative control (si-NC).

Results

A total of 152 circRNAs were differentially expressed in breast cancer tissues, among which 85 were upregulated and 67 downregulated. Out of these, hsa_circ_0011946 was selected and the subsequent bioinformatics analysis predicted that hsa_circ_0011946 sponging miR-26a/b directly targeted replication factor C subunit 3 (RFC3) and that its knockdown could inhibit RFC3 mRNA and protein expression. Furthermore, hsa_circ_0011946 loss-of-function significantly suppressed the migration and invasion of Michigan Cancer Foundation-7 cells.

Conclusion

Together, these results indicate that hsa_circ_0011946 and RFC3 comprise a novel pathway involved in the progression of breast cancer.

Expression of miR-200c and its clinicopathological significance in patients with colorectal cancer

MicroRNA-200c (miR-200c) is known to play a pivotal role in the regulation of epithelial-to-mesenchymal and mesenchymal-to-epithelial transition processes. However, the biological function of miR-200c in human carcinogenesis remains controversial. We examined the association of miR-200c expression with various clinicopathological factors, including KRAS mutation status and survival, in patients with colorectal cancer (CRC). The expression level of miR-200c was evaluated in 109 paired CRC and normal tissue samples using quantitative reverse transcription polymerase chain reaction. The KRAS mutation status of the CRC samples was determined using the PNAClamp™ KRAS Mutation Detection kit. Compared with the normal tissue group, miR-200c expression was significantly upregulated in the CRCs (P < .001). The expression of miR-200c was increased in CRCs with higher grade (P = .009), advanced stage (P = .042), and lymphovascular invasion (P = .003). Thirty-one CRCs (28.4%) had KRAS mutations in codon 12 or 13. CRCs with KRAS mutations had significantly higher miR-200c expression than CRCs with wild-type KRAS (P = .003). In survival analysis, high miR-200c expression was correlated with worse overall survival (P = .017) and recurrence-free survival (P = .048). Our results indicate that miR-200c is involved in tumor progression and aggressiveness in CRCs, and this oncogenic role of miR-200c may be triggered by activation of the KRAS signaling pathway.

The MiR-135b-BMAL1-YY1 loop disturbs pancreatic clockwork to promote tumourigenesis and chemoresistance

Circadian disruption has been implicated in tumour development, but the underlying mechanism remains unclear. Here, we show that the molecular clockwork within malignant human pancreatic epithelium is disrupted and that this disruption is mediated by miR-135b-induced BMAL1 repression. miR-135b directly targets the BMAL1 3'-UTR and thereby disturbs the pancreatic oscillator, and the downregulation of miR-135b is essential for the realignment of the cellular clock. Asynchrony between miR-135b and BMAL1 expression impairs the local circadian gating control of tumour suppression and significantly promotes tumourigenesis and resistance to gemcitabine in pancreatic cancer (PC) cells, as demonstrated by bioinformatics analyses of public PC data sets and in vitro and in vivo functional studies. Moreover, we found that YY1 transcriptionally activated miR-135b and formed a 'miR-135b-BMAL1-YY1' loop, which holds significant predictive and prognostic value for patients with PC. Thus, our work has identified a novel signalling loop that mediates pancreatic clock disruption as an important mechanism of PC progression and chemoresistance.