MicroRNA-7 inhibits epithelial-to-mesenchymal transition and metastasis of breast cancer cells via targeting FAK expression

Identification of TIMP1-induced dysregulation of epithelial-mesenchymal transition as a key pathway in inflammatory bowel disease and small intestinal neuroendocrine tumors shared pathogenesis

Inflammatory Bowel Disease (IBD) is believed to be a risk factor for Small Intestinal Neuroendocrine Tumors (SI-NET) development; however, the molecular relationship between IBD and SI-NET has yet to be elucidated. In this study, we use a systems biology approach to uncover such relationships. We identified a more similar transcriptomic-wide expression pattern between Crohn's Disease (CD) and SI-NET whereas a higher proportion of overlapping dysregulated genes between Ulcerative Colitis (UC) and SI-NET. Enrichment analysis indicates that extracellular matrix remodeling, particularly in epithelial-mesenchymal transition and intestinal fibrosis mediated by TIMP1, is the most significantly dysregulated pathway among upregulated genes shared between both IBD subtypes and SI-NET. However, this remodeling occurs through distinct regulatory molecular mechanisms unique to each IBD subtype. Specifically, myofibroblast activation in CD and SI-NET is mediated through IL-6 and ciliary-dependent signaling pathways. Contrarily, in UC and SI-NET, this phenomenon is mainly regulated through immune cells like macrophages and the NCAM signaling pathway, a potential gut-brain axis in the context of these two diseases. In both IBD and SI-NET, intestinal fibrosis resulted in significant metabolic reprogramming of fatty acid and glucose to an inflammatory- and cancer-inducing state. This altered metabolic state, revealed through enrichment analysis of downregulated genes, showed dysfunctions in oxidative phosphorylation, gluconeogenesis, and glycogenesis, indicating a shift towards glycolysis. Also known as the Warburg effect, this glycolytic switch, in return, exacerbates fibrosis. Corresponding to enrichment analysis results, network construction and subsequent topological analysis pinpointed 7 protein complexes, 17 hub genes, 11 microRNA, and 1 transcription factor related to extracellular matrix accumulation and metabolic reprogramming that are candidate biomarkers in both IBD and SI-NET. Together, these biological pathways and candidate biomarkers may serve as potential therapeutic targets for these diseases.

MicroRNA signature of stromal-epithelial interactions in prostate and breast cancers

Stromal-epithelial communication is an absolute necessity when it comes to the morphogenesis and pathogenesis of solid tissues, including the prostate and breast. So far, signalling pathways of several growth factors have been investigated. Besides such chemical factors, non-coding RNAs such as miRNAs have recently gained much interest because of their variety and complexity of action. Prostate and breast tissues being highly responsive to steroid hormones such as androgen and estrogen, respectively, it is not surprising that a huge set of available literature critically investigated the interplay between such hormones and miRNAs, especially in carcinogenesis. This review showcases our effort to highlight hormonally-related miRNAs that also somehow perturb the regular stromal-epithelial interactions during carcinogenesis in the prostate and breast. In future, we look forward to exploring how hormonal changes in the tissue microenvironment bring about miRNA-mediated changes in stromal-epithelial interactome in carcinogenesis and cancer progression.

The potential of miRNA-based approaches in glioblastoma: An update in current advances and future perspectives

Glioblastoma (GBM) is the most common malignant central nervous system tumor. The emerging field of epigenetics stands out as particularly promising. Notably, the discovery of micro RNAs (miRNAs) has paved the way for advancements in diagnosing, treating, and prognosticating patients with brain tumors. We aim to provide an overview of the emergence of miRNAs in GBM and their potential role in the multifaceted management of this disease. We discuss the current state of the art regarding miRNAs and GBM. We performed a narrative review using the MEDLINE/PUBMED database to retrieve peer-reviewed articles related to the use of miRNA approaches for the treatment of GBMs. MiRNAs are intrinsic non-coding RNA molecules that regulate gene expression mainly through post-transcriptional mechanisms. The deregulation of some of these molecules is related to the pathogenesis of GBM. The inclusion of molecular characterization for the diagnosis of brain tumors and the advent of less-invasive diagnostic methods such as liquid biopsies, highlights the potential of these molecules as biomarkers for guiding the management of brain tumors such as GBM. Importantly, there is a need for more studies to better examine the application of these novel molecules. The constantly changing characterization and approach to the diagnosis and management of brain tumors broaden the possibilities for the molecular inclusion of novel epigenetic molecules, such as miRNAs, for a better understanding of this disease.

STR mutations on chromosome 15q cause thyrotropin resistance by activating a primate-specific enhancer of MIR7-2/MIR1179

Thyrotropin (TSH) is the master regulator of thyroid gland growth and function. Resistance to TSH (RTSH) describes conditions with reduced sensitivity to TSH. Dominantly inherited RTSH has been linked to a locus on chromosome 15q, but its genetic basis has remained elusive. Here we show that non-coding mutations in a (TTTG)4 short tandem repeat (STR) underlie dominantly inherited RTSH in all 82 affected participants from 12 unrelated families. The STR is contained in a primate-specific Alu retrotransposon with thyroid-specific cis-regulatory chromatin features. Fiber-seq and RNA-seq studies revealed that the mutant STR activates a thyroid-specific enhancer cluster, leading to haplotype-specific upregulation of the bicistronic MIR7-2/MIR1179 locus 35 kb downstream and overexpression of its microRNA products in the participants' thyrocytes. An imbalance in signaling pathways targeted by these micro-RNAs provides a working model for this cause of RTSH. This finding broadens our current knowledge of genetic defects altering pituitary-thyroid feedback regulation.

Non-coding RNAs as potential therapeutic targets for receptor tyrosine kinase signaling in solid tumors: current status and future directions

This review article presents an in-depth analysis of the current state of research on receptor tyrosine kinase regulatory non-coding RNAs (RTK-RNAs) in solid tumors. RTK-RNAs belong to a class of non-coding RNAs (nc-RNAs) responsible for regulating the expression and activity of receptor tyrosine kinases (RTKs), which play a critical role in cancer development and progression. The article explores the molecular mechanisms through which RTK-RNAs modulate RTK signaling pathways and highlights recent advancements in the field. This include the identification of potential new RTK-RNAs and development of therapeutic strategies targeting RTK-RNAs. While the review discusses promising results from a variety of studies, encompassing in vitro, in vivo, and clinical investigations, it is important to acknowledge the challenges and limitations associated with targeting RTK-RNAs for therapeutic applications. Further studies involving various cancer cell lines, animal models, and ultimately, patients are necessary to validate the efficacy of targeting RTK-RNAs. The specificity of ncRNAs in targeting cellular pathways grants them tremendous potential, but careful consideration is required to minimize off-target effects, the article additionally discusses the potential clinical applications of RTK-RNAs as biomarkers for cancer diagnosis, prognosis, and treatment. In essence, by providing a comprehensive overview of the current understanding of RTK-RNAs in solid tumors, this review emphasizes their potential as therapeutic targets for cancer while acknowledging the associated challenges and limitations.

Genetic variations in tumor-suppressor miRNA-encoding genes and their target genes: focus on breast cancer development and possible therapeutic strategies

MicroRNAs (miRNAs) negatively affect gene expression by binding to their specific mRNAs resulting in either mRNA destruction or translational repression. The aberrant expression of various miRNAs has been associated with a number of human cancer. Oncogenic or tumor-suppressor miRNAs regulate a variety of pathways involved in the development of breast cancer (BC), including cell proliferation, apoptosis, metastasis, cancer recurrence, and chemoresistance. Variations in miRNA-encoding genes and their target genes lead to dysregulated gene expression resulting in the development and progression of BC. The various therapeutic approaches to treat the disease include chemotherapy, radiation therapy, surgical removal, hormone therapy, chemotherapy, and targeted biological therapy. The purpose of the current review is to explore the genetic variations in tumor-suppressor miRNA-encoding genes and their target genes in association with the disease development and prognosis. The therapeutic interventions targeting the variants for better disease outcomes have also been discussed.

Expression of pY397-FAK and Its miR Regulators Drive Dedifferentiation in the Thyroid Neoplasia Spectrum

Thyroid carcinomas are growing malignancies worldwide. They encompass several diagnostic categories with varying degrees of dedifferentiation. Focal adhesion kinase is involved in cellular communication and locomotion. It is regulated on a posttranscriptional level by miR-7, miR-135a, and miR-138 and on a posttranslational level by autophosphorylation at Y397 (pY397-FAK). We related regulators of FAK with histologic dedifferentiation, clinicopathological factors, and differential diagnosis in the thyroid neoplasia spectrum. We classified 82 cases into 5 groups with increasing aggressiveness: healthy tissue, follicular and classical variants of papillary thyroid carcinoma (PTC), dedifferentiated PTC, and anaplastic carcinoma. MiRs were analyzed by RT-qPCR. Protein expression of pY397-FAK was analyzed by immunohistochemistry (separately in the membrane, cytoplasm, and nuclear compartment) and Western blot. All three miRs were upregulated in healthy tissue compared to malignant, while pY397-FAK was downregulated. MiRs and pY397-FAK were not mutually correlated. MiR-135a-5p was decreasing while membranous and cytoplasmic pY397-FAK increased with dedifferentiation. Neither miR correlated with clinicopathological factors. MiR-135a-5p, miR-138-5p, and membranous and cytoplasmic pY397-FAK discriminated the follicular from the classical variant of PTC. Disturbances of FAK regulation on different levels contribute to neoplastic dedifferentiation. pY397-FAK exerts its oncogenic role in the membrane and cytoplasm. Diagnostically, miRs-135a-5p, miR-138-5p, and membranous and cytoplasmic pY397-FAK differentiated between classical and follicular PTC.

Therapeutic and diagnostic applications of exosomal circRNAs in breast cancer

Circular RNAs (circRNAs) are regulatory elements that are involved in orchestrating gene expression and protein functions and are implicated in various biological processes including cancer. Notably, breast cancer has a significant mortality rate and is one of the most common malignancies in women. CircRNAs have been demonstrated to contribute to the pathogenesis of breast cancer including its initiation, progression, metastasis, and resistance to drugs. By acting as miRNA sponges, circRNAs can indirectly influence gene expression by disrupting miRNA regulation of their target genes, ultimately altering the course of cancer development and progression. Additionally, circRNAs can interact with proteins and modulate their functions including signaling pathways involved in the initiation and development of cancer. Recently, circRNAs can encode peptides that play a role in the pathophysiology of breast cancer and other diseases and their potential as diagnostic biomarkers and therapeutic targets for various cancers including breast cancer. CircRNAs possess biomarkers that differentiate, such as stability, specificity, and sensitivity, and can be detected in several biological specimens such as blood, saliva, and urine. Moreover, circRNAs play an important role in various cellular processes including cell proliferation, differentiation, and apoptosis, all of which are integral factors in the development and progression of cancer. This review synthesizes the functions of circRNAs in breast cancer, scrutinizing their contributions to the onset and evolution of the disease through their interactions with exosomes and cancer-related intracellular pathways. It also delves into the potential use of circRNA as a biomarker and therapeutic target against breast cancer. It discusses various databases and online tools that offer crucial circRNA information and regulatory networks. Lastly, the challenges and prospects of utilizing circRNAs in clinical settings associated with breast cancer are explored.

Molecular mechanism of the miR-7/BCL2L1/P53 signaling axis regulating the progression of hepatocellular carcinoma

Background

To investigate the roles of miR-7 and its potential mechanisms in hepatocellular carcinoma (HCC).

Methods

The functions of miR-7 were identified and measured by MTT [3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide], colony formation, transwell, and flow cytometry assays. A luciferase assay was applied to verify the direct binding of miR-7 on BCL2L1 3'untranslated region (3'UTR). An in vitro experiment was then used to investigate the biological effects of miR-7 and BCL2L1. A co-immunoprecipitation (COIP) assay was used to detect the protein interaction between BCL2L1 and P53.

Results

We found that miR-7 overexpression suppressed cell proliferation, migration, and invasion in HCC. BCL2L1 was also demonstrated as a direct target gene of miR-7. This study showed that BCL2L1 could partially rescue the inhibitory effect of miR-7 on the proliferation, migration, and invasion of HCC cells. Our research showed that miR-7 could inhibit the epithelial-mesenchymal transition (EMT) pathway by regulating BCL2L1. We also further confirmed that miR-7 inhibits the proliferation, migration, and invasion of Hep3B and Huh7 cells by targeting BCL2L1. Furthermore, we observed that the BCL2L1 protein interacts with the P53 protein and BCL2L1 affects the development of liver cancer through P53. We also found that BCL2L1 could promote the invasion and migration of liver cancer cells through P53 inhibition. BCL2L1 also inhibited the expression of Caspase 3/7 in hepatoma cells by inhibiting the expression of P53.

Conclusions

Our study demonstrated that miR-7/BCL2L1/P53 may serve as a regulatory molecular axis for HCC treatment. Our results suggest that miR-7/BCL2L1/P53 may have predictive value and represent a new treatment strategy for liver cancer.

The Role of microRNAs in Inflammation

Inflammation is a biological response of the immune system to various insults, such as pathogens, toxic compounds, damaged cells, and radiation. The complex network of pro- and anti-inflammatory factors and their direction towards inflammation often leads to the development and progression of various inflammation-associated diseases. The role of small non-coding RNAs (small ncRNAs) in inflammation has gained much attention in the past two decades for their regulation of inflammatory gene expression at multiple levels and their potential to serve as biomarkers and therapeutic targets in various diseases. One group of small ncRNAs, microRNAs (miRNAs), has become a key regulator in various inflammatory disease conditions. Their fine-tuning of target gene regulation often turns out to be an important factor in controlling aberrant inflammatory reactions in the system. This review summarizes the biogenesis of miRNA and the mechanisms of miRNA-mediated gene regulation. The review also briefly discusses various pro- and anti-inflammatory miRNAs, their targets and functions, and provides a detailed discussion on the role of miR-10a in inflammation.

The molecular mechanism of baicalein repressing progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway

BACKGROUND

Baicalein (BAI) has a significant anti-cancerous function in the treatment of gastric cancer (GC). Focal adhesion kinase (FAK) is a key regulatory molecule in integrin and growth factor receptor mediated signaling. MicroRNA-7 (miR-7), has been considered as a potential tumor suppressor in a variety of cancers. However, the possible mechanisms by which BAI inhibiting progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway remain unclear.

PURPOSE

To investigate the molecular mechanism and effects of BAI inhibiting progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway.

METHODS

Gastric cancer cell lines with FAK knockdown and overexpression were constructed by lentivirus transfection. After BAI treatment, the effects of FAK protein on proliferation, metastasis and angiogenesis of gastric cancer cells were detected by MTT, EdU, colony formation, wound healing, transwell and Matrigel tube formation assays. In vivo experiment was performed by xenograft model. Immunofluorescence and western blot assay were used to detect the effects of FAK protein on the expression levels of EMT markers and PI3K/AKT signaling pathway related proteins. qRT-PCR and luciferase reporter assay were used to clarify the targeting relationship between miR-7 and FAK.

RESULTS

BAI can regulate FAK to affect proliferation, metastasis and angiogenesis of gastric cancer cells through PI3K/AKT signaling pathway. qRT-PCR showed BAI can upregulated the expression of miR-7 and luciferase reporter assay showed the targeting relationship between miR-7 and FAK. Additionally, miR-7 mediates cell proliferation, metastasis and angiogenesis by directly targeting FAK 3'UTR to inhibit FAK expression.

CONCLUSION

BAI repressing progression of gastric cancer mediating miR-7/FAK/AKT signaling pathway.

Long noncoding RNA BMPR1B-AS1 facilitates endometrial cancer cell proliferation and metastasis by sponging miR-7-2-3p to modulate the DCLK1/Akt/NF-κB pathway

Endometrial carcinoma (EC) originates from the endometrium and is one of the most common tumors in female patients, and its incidence has continued to increase in recent decades. LncRNAs are involved in the pathogenesis and metastasis of a variety of malignant tumors, which indicates that lncRNAs can be used as tumor diagnostic markers and potential therapeutic targets. In this study, we analyzed the RNA transcripts of EC cells from The Cancer Genome Atlas (TCGA) and first reported a novel lncRNA, BMPR1B-AS1, that was more highly expressed in endometrial cancer tissues than in adjacent tissues, and BMPR1B-AS1 could promote endometrial cancer cell proliferation and metastasis. Bioinformatics prediction and experimental results both suggested that BMPR1B-AS1 could modulate the malignant behaviors of endometrial cancer cell lines by sponging miR-7-2-3p to modulate DCLK1, and a DCLK1 inhibitor blocked the activation of the PI3K/Akt/NF-κB signaling pathway. Collectively, this study suggests that the BMPR1B-AS1/miR-7-2-3p/DCLK1 axis contributes to the proliferation and metastasis of endometrial cancer cells via the PI3K/Akt/NF-κB pathway.

FAK in Cancer: From Mechanisms to Therapeutic Strategies

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, is overexpressed and activated in many cancer types. FAK regulates diverse cellular processes, including growth factor signaling, cell cycle progression, cell survival, cell motility, angiogenesis, and the establishment of immunosuppressive tumor microenvironments through kinase-dependent and kinase-independent scaffolding functions in the cytoplasm and nucleus. Mounting evidence has indicated that targeting FAK, either alone or in combination with other agents, may represent a promising therapeutic strategy for various cancers. In this review, we summarize the mechanisms underlying FAK-mediated signaling networks during tumor development. We also summarize the recent progress of FAK-targeted small-molecule compounds for anticancer activity from preclinical and clinical evidence.

Bone mesenchymal stem cell-derived exosomal microRNA-7-5p inhibits progression of acute myeloid leukemia by targeting OSBPL11

BACKGROUND

Acute myeloid leukemia (AML) is a malignant clonal disease of hematopoietic stem- and progenitor-cell origin. AML features massive proliferation of abnormal blasts and leukemia cells in the bone marrow and the inhibition of normal hematopoiesis at onset. Exosomes containing proteins or nucleic acids are secreted by cells; they participate in intercellular communication and serve as key modulators of hematopoiesis. The purpose of this study was to investigate the effects of exosomes derived from bone marrow mesenchymal stem cells (BMSCs) on the regulation of AML and the underlying mechanisms mediated by microRNA (miRNA).

METHODS

Dysregulated miR-7-5p in AML patients was identified using qRT-PCR and its clinical significance was explored. Bioinformatic analysis revealed the target gene OSBPL11 that could be regulated by miR-7-5p. The findings were validated using a dual-luciferase reporter assay and western blotting. The functional genes of the PI3K/AKT/mTOR signaling pathway were identified, and the functional significance of miR-7-5p in AML cells was determined using a functional recovery assay. AML cells were co-cultured with exosomes originating from BMSCs overexpressing miR-7-5p to determine cell-cell regulation by Exo-miR-7-5p, as well as in vitro and in vivo functional validation via gain- and loss-of-function methods.

RESULTS

Expression of miR-7-5p was decreased in AML patients and cells. Overexpression of miR-7-5p curbed cellular proliferation and promoted apoptosis. Overexpression of OSBPL11 reversed the tumorigenic properties of miR-7-5p in AML cells in vitro. Exo-miR-7-5p derived from BMSCs induced formation of AML cells prone to apoptosis and a low survival rate, with OSBPL11 expression inhibited through the PI3K/AKT/mTOR signaling pathway. Exo-miR-7-5p derived from BMSCs exhibited tumor homing effects in vitro and in vivo, and inhibited AML development.

CONCLUSIONS

Exo-miR-7-5p derived from BMSCs negatively regulates OSBPL11 by suppressing the phosphorylation of the PI3K/AKT/mTOR signaling pathway, thereby inhibiting AML proliferation and promoting apoptosis. The data will inform the development of AML therapies based on BMSC-derived exosomes.

CircRNAs: Insights into Gastric Cancer

Background

Gastric cancer (GC) is recorded as the fifth most common cancer globally. The classic resemblance of early symptoms of chronic gastritis including nausea, dysphagia, and dyspepsia with GC is the current challenge limiting the early diagnosis of GC. The current diagnostic procedures of GC are limited due to their invasive nature. This directs the research question toward alternative approaches, specifically at the molecular level. Recent advances in molecular regulation of cancer suggest the prominence of circular RNAs (circRNAs) in the multistep process of tumourigenesis.

Summary

CircRNAs are a class of non-coding RNAs, abundant in eukaryotes, with key roles in regulating genes and miRNAs as well as the alteration of processes involved in pathological conditions. Research studies have demonstrated the participation of circRNAs in the initiation and progression of tumours. This review provides a comprehensive insight into the potential of circRNAs as disease biomarkers for the early detection and treatment of GC.

Key Messages

This study is an amalgamation of the implications and future prospects of circRNAs for the detection and potential treatment of GC.

A Network Pharmacology Analysis of the Systems-Perspective Anticancer Mechanisms of the Herbal Drug FDY2004 for Breast Cancer

Breast cancer is a malignant tumor with high incidence, prevalence, and mortality rates in women. In recent years, herbal drugs have been assessed as anticancer therapy against breast cancer, owing to their promising therapeutic effects and reduced toxicity. However, their pharmacological mechanisms have not been fully explored at the systemic level. Here, we conducted a network pharmacology analysis of the systems-perspective molecular mechanisms of FDY2004, an anticancer herbal formula that consists of Moutan Radicis Cortex, Persicae Semen , and Rhei Radix et Rhizoma, against breast cancer. We determined that FDY2004 may contain 28 active compounds that exert pharmacological effects by targeting 113 breast cancer-related human genes/proteins. Based on the gene ontology terms, the FDY2004 targets were involved in modulating biological processes such as cell growth, cell proliferation, and apoptosis. Pathway enrichment analysis identified various breast cancer-associated pathways that may mediate the anticancer activity of FDY2004, including the PI3K-Akt, MAPK, TNF, HIF-1, focal adhesion, estrogen, ErbB, NF-kappa B, p53, and VEGF signaling pathways. Thus, our analysis offers novel insights into the anticancer properties of herbal drugs for breast cancer treatment from a systemic perspective.

Potential role of microRNAs as biomarkers in human glioblastoma: a mini systematic review from 2015 to 2020

Glioblastoma (GBM) is the most common, aggressive and malignant type of glioma, with poor prognosis, despite advances in medical knowledge and technology. It's known that some microRNAs (miRNAs) can be dysregulated and associated with tumors. We aim to investigate miRNAs that may have a role as potential biomarkers in human glioblastoma. A search was performed using PubMed, LILACS and SCIELO databases to find papers from 2015 to 2020, related to human in vitro and ex vivo data. From 99 articles, 10 were eligible and 13 dysregulated miRNAs were found with description of regulation, target(s), pathway(s) and mechanism(s). The miRNAs of interest were found and seem to be involved in development and progression of glioblastoma and used as target therapies. Understanding the mechanisms in which those miRNAs are involved and their role in epigenetic pathways that lead to cancer, as well as their potential in clinical application, may improve GBM clinical outcome (CRD42020182706, 07/10/2020, retrospectively registered).

Long Non-Coding RNA LINC00467 Correlates to Poor Prognosis and Aggressiveness of Breast Cancer

Breast cancer remains the leading cause of female cancer-related mortalities worldwide. Long non-coding RNAs (LncRNAs) have been increasingly reported to play pivotal roles in tumorigenesis and cancer progression. Herein, we focused on LINC00467, which has never been studied in breast cancer. Silence of LINC00467 suppressed proliferation, migration, invasion and epithelial-to-mesenchymal transition (EMT) of breast cancer cells in vitro, whereas forced expression of LINC00467 exhibited the opposite effects. Furthermore, we demonstrated overexpression of LINC00467 promoted tumor growth, while knockdown of LINC00467 inhibited pulmonary metastasis in vivo. Mechanistically, LINC00467 down-regulated miR-138-5p by acting as a miRNA “sponge”. Besides, LINC00467 also up-regulated the protein level of lin-28 homolog B (LIN28B) via a direct interaction. A higher expression level of LINC00467 was observed in breast cancer tissues as compared to the adjacent normal counterparts and elevated LINC00467 predicted poor overall survival. Our findings suggest LINC00467 promotes progression of breast cancer through interacting with miR-138-5p and LIN28B directly. LINC00467 may serve as a potential candidate for the diagnosis and treatment of breast cancer.

MiR-7 in Cancer Development

MicroRNAs (miRNAs) are short non-coding RNA involved in the regulation of specific mRNA translation. They participate in cellular signaling circuits and can act as oncogenes in tumor development, so-called oncomirs, as well as tumor suppressors. miR-7 is an ancient miRNA involved in the fine-tuning of several signaling pathways, acting mainly as tumor suppressor. Through downregulation of PI3K and MAPK pathways, its dominant role is the suppression of proliferation and survival, stimulation of apoptosis and inhibition of migration. Besides these functions, it has numerous additional roles in the differentiation process of different cell types, protection from stress and chromatin remodulation. One of the most investigated tissues is the brain, where its downregulation is linked with glioblastoma cell proliferation. Its deregulation is found also in other tumor types, such as in liver, lung and pancreas. In some types of lung and oral carcinoma, it can act as oncomir. miR-7 roles in cell fate determination and maintenance of cell homeostasis are still to be discovered, as well as the possibilities of its use as a specific biotherapeutic.

circHIPK3 regulates proliferation and differentiation of myoblast through the miR-7/TCF12 pathway

Skeletal muscle development is a complex biological process involving multiple key genes, signaling pathways and noncoding RNAs, including microRNAs and circular RNAs (circRNAs). However, the regulatory relationship among them is so complicated that it has not yet been fully elucidated. In this study, we found that miR-7 inhibited C2C12 cell proliferation and differentiation by targeting transcription factor 12 (TCF12). circHIPK3 acted as a competing endogenous RNA, and its overexpression effectively reversed the regulation of miR-7 on C2C12 cell proliferation and differentiation by increasing TCF12 expression. Taken together, our findings provide evidence that circHIPK3 regulates skeletal muscle development through the miR-7/TCF12 pathway. This study provides a scientific basis for further research on skeletal muscle development at the circRNA level.

The Role of miRNA-7 in the Biology of Cancer and Modulation of Drug Resistance

MicroRNAs (miRNAs, miRs) are small non-coding RNA (ncRNA) molecules capable of regulating post-transcriptional gene expression. Imbalances in the miRNA network have been associated with the development of many pathological conditions and diseases, including cancer. Recently, miRNAs have also been linked to the phenomenon of multidrug resistance (MDR). MiR-7 is one of the extensively studied miRNAs and its role in cancer progression and MDR modulation has been highlighted. MiR-7 is engaged in multiple cellular pathways and acts as a tumor suppressor in the majority of human neoplasia. Its depletion limits the effectiveness of anti-cancer therapies, while its restoration sensitizes cells to the administered drugs. Therefore, miR-7 might be considered as a potential adjuvant agent, which can increase the efficiency of standard chemotherapeutics.

Impact of Acidosis-Regulated MicroRNAs on the Expression of Their Target Genes in Experimental Tumors In Vivo

In comparison to normal tissue, solid tumors show an acidic extracellular pH, which results from hypoxia-induced glycolytic metabolism and the Warburg effect. Since acidosis modulates the expression of different microRNAs (e.g., miR-7, miR-183, miR-203, miR-215), microRNAs and their targets might be mediators between tumor acidosis and malignant behavior. The aim of this study was to investigate how modulation of these microRNAs affects the expression of their targets (Crem, cAMP-responsive element modulator; Gls2, glutaminase 2; Txnip, thioredoxin-interacting protein) in experimental tumors in vivo and whether these changes are acidosis dependent. The study was performed in two experimental tumor lines of the rat (AT-1 prostate carcinoma, Walker-256 mammary carcinoma). The results showed that all three targets were regulated by acidosis in vivo, Crem and Gls2 being downregulated and Txnip upregulated in both models. In AT-1 tumors at normal tumor pH, miR-203 overexpression increased Txnip expression by about 75%, whereas in Walker-256 tumors, miR-7 reduced protein expression. In more acidic tumors, no impact of microRNAs on Txnip expression was seen. On the other hand, Gls2 was significantly increased in acidic tumors by miR-183 or miR-7 overexpression (cell line dependent). As this increase was not present under control conditions, an acidosis-dependent effect can be assumed. These results indicate that tumor acidosis modulates the expression of targets of pH-sensitive microRNAs in experimental tumors. Especially the protein expression of Gls2 might be regulated via changes of microRNAs, which then affects the malignant progression of tumors.

The role of tumor suppressor short non-coding RNAs on breast cancer

Characterized by remarkable levels of aggression and malignancy, BC remains one of the leading causes of death in females world wide. Accordingly, significant efforts have been made to develop early diagnostic tools, increase treatment efficacy, and improve patient prognosis. Hopefully, many of the molecular mechanisms underlying BC have been detected and show promising targeting potential. In particular, short and long non-coding RNAs (ncRNAs) are a class of endogenous BC controllers and include a number of different species including microRNAs, Piwi-interacting RNAs, small nucleolar RNA, short interfering RNAs, and tRNA-derivatives. In this review, we discuss the tumor suppressing roles of ncRNAs in the context of BC, and the mechanisms by which ncRNAs target tumor hallmarks, including apoptosis, proliferation, invasion, metastasis, epithelial-mesenchymal transition, angiogenesis, and cell cycle progression, in addition to their diagnostic and prognostic significance in cancer treatment.

Integrin α2β1 inhibition attenuates prostate cancer cell proliferation by cell cycle arrest, promoting apoptosis and reducing epithelial-mesenchymal transition

Integrin α2β1 plays an important role in cellular migration and metastasis processes associated with prostate cancer. The aim of this study was to assess whether selective inhibition of integrin α2β1 is an effective strategy to target metastatic prostate cancer cells. In this regard, we examined the effects of the inhibitor BTT-3033, which selectively interferes with the connection between integrin a2b1 and its ligand, on migration, epithelial-mesenchymal transition (EMT), cell cycle arrest, apoptosis, and specific intracellular signaling pathways using LNcap-FGC and DU-145 prostate cancer cell lines. Western blot analysis and immunocytochemistry assays showed that inhibition of integrin a2b1 inhibits EMT, through the increased expression of E-cadherin and decreased expression of N-cadherin and vimentin. Scratch wound healing assays revealed a direct effect on integrin α2β1 in the migration capacity of cells. In addition, treatment with BTT-3033 induced a reduction in cell viability and proliferation, as assessed by MTT and BrdU assays. In addition, the results show that BTT-3033 inhibits cell proliferation by inducing G1 cell cycle arrest. Moreover, inhibition of integrin α2β1 induces apoptosis through the activation of ROS, Bax protein upregulation, caspase-3 activation, and depletion of ΔΨm.  Molecular signaling studies showed that integrin α2β1 was a positive regulator of MKK7 phosphorylation. In conclusion, our results reveal a critical role for integrin a2b1 in the proliferation of prostate cancer cells, as demonstrated by EMT inhibition, cell cycle arrest, and apoptosis induction in response to treatment with its specific inhibitor BT-3033.

Regulators at Every Step-How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial-mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Regulators at Every Step—How microRNAs Drive Tumor Cell Invasiveness and Metastasis

Tumor cell invasiveness and metastasis are the main causes of mortality in cancer. Tumor progression is composed of many steps, including primary tumor growth, local invasion, intravasation, survival in the circulation, pre-metastatic niche formation, and metastasis. All these steps are strictly controlled by microRNAs (miRNAs), small non-coding RNA that regulate gene expression at the post-transcriptional level. miRNAs can act as oncomiRs that promote tumor cell invasion and metastasis or as tumor suppressor miRNAs that inhibit tumor progression. These miRNAs regulate the actin cytoskeleton, the expression of extracellular matrix (ECM) receptors including integrins and ECM-remodeling enzymes comprising matrix metalloproteinases (MMPs), and regulate epithelial–mesenchymal transition (EMT), hence modulating cell migration and invasiveness. Moreover, miRNAs regulate angiogenesis, the formation of a pre-metastatic niche, and metastasis. Thus, miRNAs are biomarkers of metastases as well as promising targets of therapy. In this review, we comprehensively describe the role of various miRNAs in tumor cell migration, invasion, and metastasis.

Progress in the Development of Small Molecular Inhibitors of Focal Adhesion Kinase (FAK)

Focal adhesion kinase (FAK) is a nonreceptor intracellular tyrosine kinase that plays an essential role in cancer cell adhesion, survival, proliferation, and migration through both its enzymatic activities and scaffolding functions. Overexpression of FAK has been found in many human cancer cells from different origins, which promotes tumor progression and influences clinical outcomes in different classes of human tumors. Therefore, FAK has been considered as a promising target for small molecule anticancer drug development. Many FAK inhibitors targeting different domains of FAK with various mechanisms of functions have been reported, including kinase domain inhibitors, FERM domain inhibitors, and FAT domain inhibitors. In addition, FAK-targeting PROTACs, which can induce the degradation of FAK, have also been developed. In this Perspective, we summarized the progress in the development of small molecular FAK inhibitors and proposed the perspectives for the future development of agents targeting FAK.

UV-type specific alteration of miRNA expression and its association with tumor progression and metastasis in SCC cell lines

PURPOSE

UV exposure is the main risk factor for development of cutaneous squamous cell carcinoma (cSCC). While early detection greatly improves cSCC prognosis, locally advanced or metastatic cSCC has a severely impaired prognosis. Notably, the mechanisms of progression to metastatic cSCC are not well understood. We hypothesized that UV exposure of already transformed epithelial cSCC cells further induces changes which might be involved in the progression to metastatic cSCCs and that UV-inducible microRNAs (miRNAs) might play an important role.

METHODS

Thus, we analyzed the impact of UV radiation of different quality (UVA, UVB, UVA + UVB) on the miRNA expression pattern in established cell lines generated from primary and metastatic cSCCs (Met-1, Met-4) using the NanoString nCounter platform.

RESULTS

This analysis revealed that the expression pattern of miRNAs depends on both the cell line used per se and on the quality of UV radiation. Comparison of UV-induced miRNAs in cSCC cell lines established from a primary tumor (Met-1) and the respective (un-irradiated) metastasis (Met-4) suggest that miR-7-5p, miR-29a-3p and miR-183-5p are involved in a UV-driven pathway of progression to metastasis. This notion is supported by the fact that these three miRNAs build up a network of 81 potential target genes involved e.g. in UVA/UVB-induced MAPK signaling and regulation of the epithelial-mesenchymal transition. As an example, PTEN, a target of UV-upregulated miRNAs (miR-29a-3p, miR-183-5p), could be shown to be down-regulated in response to UV radiation. We further identified CNOT8, the transcription complex subunit 8 of the CCR4-NOT complex, a deadenylase removing the poly(A) tail from miRNA-destabilized mRNAs, in the center of this network, targeted by all three miRNAs.

CONCLUSION

In summary, our results demonstrate that UV radiation induces an miRNA expression pattern in primary SCC cell line partly resembling those of metastatic cell line, thus suggesting that UV radiation impacts SCC progression beyond initiation.

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.

Oncogenic microRNA-765 promotes the growth and metastasis of breast carcinoma by directly targeting ING4

Previous investigations have proved that microRNA (miR)-765 is significantly overexpressed in multiple tumor types. Nevertheless, the underlying molecular mechanism of miR-765 in mediating breast carcinoma cell growth and metastasis remains unclear. Quantitative real-time polymerase chain reaction was used to determine the levels of miR-765 and inhibitor of growth 4 (ING4) in breast carcinoma tissues and breast carcinoma cells. Cell proliferation, colony formation, wound healing, and Transwell invasion assays were used to analysis the role of miR-765 on breast carcinoma cell growth and aggressiveness. The expressions of ING4 were determined using Western blot analysis and immunohistochemical staining. The direct target of ING4 and miR-765 was confirmed using the luciferase reporter assay. Nude mice were subcutaneously implanted with miR-765 inhibitor transfected MDA-MB-231 cells to determine the potential role of miR-765 in tumor growth in vivo. We observed that miR-765 is overexpressed in breast carcinoma tissue and breast cancer cells. By using luciferase reporter gene bioassay, we find that ING4 is the direct target of miR-765 in breast carcinoma. The level of ING4 is inversely associated with the level of miR-765. The gain-of-function and loss-of-function experiments in vitro indicate that the downregulation of miR-765 suppresses the growth, mobility, and invasion abilities of breast cancer cells by inhibiting ING4. In addition, overexpression of ING4 suppresses the aggressiveness of the MDA-BA-231 cell that is induced by miR-761 in vitro. In this study, we prove that miR-765 regulates the growth and metastasis of breast cancer via modulating miR-765-ING4-negative feedback loop.

MicroRNA-Dependent Targeting of RSU1 and the IPP Adhesion Complex Regulates the PTEN/PI3K/AKT Signaling Pathway in Breast Cancer Cell Lines

(1) Background: The microRNA (miR)-directed control of gene expression is correlated with numerous physiological processes as well as the pathological features of tumors. The focus of this study is on the role of miRs in the regulation of RSU1 and proteins in the IPP (integrin linked kinase, PINCH and parvin) complex. Because the IPP adaptor proteins link β integrins to actin cytoskeleton, and the RSU1 signaling protein connects the complex to the activation of cJun, ATF2 and the transcription of PTEN, their reduction by miRs has the potential to alter both adhesion and survival signaling. (2) Methods: Multiple database analyses were used to identify miRs that target RSU1 and PINCH1. miR transfection validated the effects of miRs on RSU1, PINCH1 and downstream targets in breast cancer cell lines. (3) Results: The miRs targeting RSU1 mRNA include miR-182-5p, -409-3p, -130a-3p, -221-3p, -744-5p and -106b-5p. Data show that miR-182-5p and -409-3p reduce RSU1, PINCH1 and inhibit the ATF2 activation of PTEN expression. miR-221-3p and miR-130a-3p target RSU1 and PINCH1 and, conversely, RSU1 depletion increases miR-221-3p and miR-130a-3p. (4) Conclusions: miRs targeting RSU1 and PINCH1 in mammary epithelial or luminal breast cancer cell lines reduced RSU1 signaling to p38 MAP kinase and ATF2, inhibiting the expression of PTEN. miR-221-3p, known to target PTEN and cell cycle regulators, also targets RSU1 and PINCH1 in luminal breast cancer cell lines.

Focal Adhesion Kinase in Ovarian Cancer: A Potential Therapeutic Target for Platinum and Taxane-Resistant Tumors

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase, which is an essential player in regulating cell migration, invasion, adhesion, proliferation, and survival. Its overexpression and activation have been identified in sixty-eight percent of epithelial ovarian cancer patients and this is significantly associated with higher tumor stage, metastasis, and shorter overall survival of these patients. Most recently, a new role has emerged for FAK in promoting resistance to taxane and platinum-based therapy in ovarian and other cancers. The development of resistance is a complex network of molecular processes that make the identification of a targetable biomarker in platinum and taxane-resistant ovarian cancer a major challenge. FAK overexpression upregulates ALDH and XIAP activity in platinum-resistant and increases CD44, YB1, and MDR-1 activity in taxaneresistant tumors. FAK is therefore now emerging as a prognostically significant candidate in this regard, with mounting evidence from recent successes in preclinical and clinical trials using small molecule FAK inhibitors. This review will summarize the significance and function of FAK in ovarian cancer, and its emerging role in chemotherapeutic resistance. We will discuss the current status of FAK inhibitors in ovarian cancers, their therapeutic competencies and limitations, and further propose that the combination of FAK inhibitors with platinum and taxane-based therapies could be an efficacious approach in chemotherapeutic resistant disease.

Key Regulatory miRNAs and their Interplay with Mechanosensing and Mechanotransduction Signaling Pathways in Breast Cancer Progression

According to the WHO, breast cancer is the most common cancer in women worldwide. Identification of underlying mechanisms in breast cancer progression is the main concerns of researches. The mechanical forces within the tumor microenvironment, in addition to biochemical stimuli such as different growth factors and cytokines, activate signaling cascades, resulting in various changes in cancer cell physiology. Cancer cell proliferation, invasiveness, migration, and, even, resistance to cancer therapeutic agents are changed due to activation of mechanotransduction signaling. The mechanotransduction signaling is frequently dysregulated in breast cancer, indicating its important role in cancer cell features. So far, a variety of experimental investigations have been conducted to determine the main regulators of the mechanotransduction signaling. Currently, the role of miRNAs has been well-defined in the cancer process through advances in molecular-based approaches. miRNAs are small groups of RNAs (∼22 nucleotides) that contribute to various biological events in cells. The central role of miRNAs in the regulation of various mediators involved in the mechanotransduction signaling has been well clarified over the last decade. Unbalanced expression of miRNAs is associated with different pathologic conditions. Overexpression and downregulation of certain miRNAs were found to be along with dysregulation of mechanotransduction signaling effectors. This study aimed to critically review the role of miRNAs in the regulation of mediators involved in the mechanosensing pathways and clarify how the cross-talk between miRNAs and their targets affect the cell behavior and physiology of breast cancer cells.

Deep Insights in Circular RNAs: from biogenesis to therapeutics

Abstract

Circular RNAs (circRNAs) have emerged as a universal novel class of eukaryotic non-coding RNA (ncRNA) molecules and are becoming a new research hotspot in RNA biology. They form a covalent loop without 5′ cap and 3′ tail, unlike their linear counterparts. Endogenous circRNAs in mammalian cells are abundantly conserved and discovered so far. In the biogenesis of circRNAs exonic, intronic, reverse complementary sequences or RNA-binding proteins (RBPs) play a very important role. Interestingly, the majority of them are highly conserved, stable, resistant to RNase R and show developmental-stage/tissue-specific expression. CircRNAs play multifunctional roles as microRNA (miRNA) sponges, regulators of transcription and post-transcription, parental gene expression and translation of proteins in various diseased conditions. Growing evidence shows that circRNAs play an important role in neurological disorders, atherosclerotic vascular disease, and cancer and potentially serve as diagnostic or predictive biomarkers due to its abundance in various biological samples. Here, we review the biogenesis, properties, functions, and impact of circRNAs on various diseases.

Graphical Abstract

The N-terminal polypeptide derived from vMIP-II exerts its antitumor activity in human breast cancer through CXCR4/miR-7-5p/Skp2 pathway

Breast cancer is a malignant tumor with the highest incidence in women of the world. CXCR4 and Skp2 are highly expressed in breast cancer cells and CXCR4 was positively correlated with Skp2 by interference or overexpression. The microRNA array was used to detect the differentially expressed spectrum of micro RNAs in breast cancer cells the changes of miR-7-5p after CXCR4 inhibitor (NT21MP) treatment to block the CXCR4/SDF-1 pathway was founded. MiR-7-5p has been found to be correlated with Skp2 in various tumors in the literature, and Skp2 expression can be regulated by transfection with miR-7-5p mimics or inhibitors. The expression level of miR-7-5p was upregulated or downregulated after CXCR4 interference or overexpression. Combined with the correlation between CXCR4 and miR-7-5p in the chip results, CXCR4 may regulate Skp2 through miR-7-5p. Epithelial cells have the morphological characteristics of mesenchymal cells for some reason called epithelial-mesenchymal transformation (EMT). Transfection of miR-7-5p mimics into drug-resistant cells reduced Skp2 levels, decreased the expression of Vimentin, Snail, and slug, and increased the expression of E-cadherin. CXCR4 inhibitor (NT21MP) can reverse the EMT changes caused by miR-7-5p inhibitor. Similarly, in vivo results suggesting that CXCR4 inhibitors can reverse the EMT phenotype of drug-resistant breast cancer cells through the CXCR4/miR-7-5p/Skp2 pathway. In summary, the CXCR4/miR-7-5p/Skp2 signaling pathway plays an important role in the progression of breast cancer. This study provides a theoretical basis for the treatment of breast cancer by targeting the CXCR4 pathway.

Linc00668 Promotes Invasion and Stem Cell-Like Properties of Breast Cancer Cells by Interaction With SND1

Long non-coding RNAs (lncRNAs) are reported to be involved in breast cancer progression. Herein, we observed that the expression of Linc00668 was increased in breast cancer compared to normal tissue. The patients with high Linc00668 expression exhibited an association with a higher metastatic risk. We demonstrated that forced expression of Linc00668 enhanced, whereas depletion of Linc00668 diminished invasion and self-renewal of breast cancer cells as well as resistance to doxorubicin (Dox). Further mechanistic studies revealed that Linc00668 associated with staphylococcal nuclease domain-containing 1 (SND1) and regulated the expression of downstream genes. Linc00668 depletion led to reduced expression of the downstream target of SND1 and further attenuated the self-renewal capacity of breast cancer cells. Our observations suggest that Linc00668 promotes metastasis, and chemotherapeutic resistance in breast cancer by interacting with SND1. Therefore, Linc00668 may serve as a potential therapeutic modulator in breast cancer treatment.

Prognostic Value of Circular RNA ciRS-7 in Various Cancers: A PRISMA-Compliant Meta-Analysis

BACKGROUND

Circular RNAs (circRNAs) have been shown to be involved in tumorigenesis. As a member of circRNAs, ciRS-7 is thought to be a negative prognostic indicator in multiple types of cancer. The present study aimed to comprehensively explore the value of ciRS-7 in tumor malignancy. Materials and Methods. A systematic review of PubMed, Web of Science, and the Cochrane library was carried out to examine the related studies. The pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated from the available publications by STATA 12.0. Subgroup analysis, publication bias, sensitivity analysis, and meta-regression were conducted.

RESULTS

This meta-analysis included 1,714 patients from 13 cohorts. The results suggested that high ciRS-7 expression was significantly associated with overall survival (OS) (HR = 2.17, 95% CI = 1.50-3.15, P < 0.001) in various cancers. Stratified analyses indicated that elevated levels of ciRS-7 appeared to be a powerful prognostic biomarker for patients with non-small-cell lung cancer (NSCLC) (HR: 2.50, 95% CI: 1.07-6.07, P < 0.001) in various cancers. Stratified analyses indicated that elevated levels of ciRS-7 appeared to be a powerful prognostic biomarker for patients with non-small-cell lung cancer (NSCLC) (HR: 2.50, 95% CI: 1.07-6.07, P < 0.001) in various cancers. Stratified analyses indicated that elevated levels of ciRS-7 appeared to be a powerful prognostic biomarker for patients with non-small-cell lung cancer (NSCLC) (HR: 2.50, 95% CI: 1.07-6.07, P < 0.001) in various cancers. Stratified analyses indicated that elevated levels of ciRS-7 appeared to be a powerful prognostic biomarker for patients with non-small-cell lung cancer (NSCLC) (HR: 2.50, 95% CI: 1.07-6.07, P < 0.001) in various cancers. Stratified analyses indicated that elevated levels of ciRS-7 appeared to be a powerful prognostic biomarker for patients with non-small-cell lung cancer (NSCLC) (HR: 2.50, 95% CI: 1.07-6.07.

CONCLUSIONS

High expression of ciRS-7 has a significant correlation with the high stage in various cancers, and ciRS-7 is intimately associated with an adverse OS in numerous cancers. Thus, ciRS-7 may act as a potential biomarker for the development of malignancies.

Epigenetic Silencing of CDR1as Drives IGF2BP3-Mediated Melanoma Invasion and Metastasis

Metastasis is the primary cause of death of cancer patients. Dissecting mechanisms governing metastatic spread may uncover important tumor biology and/or yield promising therapeutic insights. Here, we investigated the role of circular RNAs (circRNA) in metastasis, using melanoma as a model aggressive tumor. We identified silencing of cerebellar degeneration-related 1 antisense (CDR1as), a regulator of miR-7, as a hallmark of melanoma progression. CDR1as depletion results from epigenetic silencing of LINC00632, its originating long non-coding RNA (lncRNA) and promotes invasion in vitro and metastasis in vivo through a miR-7-independent, IGF2BP3-mediated mechanism. Moreover, CDR1as levels reflect cellular states associated with distinct therapeutic responses. Our study reveals functional, prognostic, and predictive roles for CDR1as and expose circRNAs as key players in metastasis.

MicroRNAs and Metastasis

Metastasis, the development of secondary malignant growths at a distance from the primary site of a cancer, is associated with almost 90% of all cancer deaths, and half of all cancer patients present with some form of metastasis at the time of diagnosis. Consequently, there is a clear clinical need for a better understanding of metastasis. The role of miRNAs in the metastatic process is beginning to be explored. However, much is still to be understood. In this review, we present the accumulating evidence for the importance of miRNAs in metastasis as key regulators of this hallmark of cancer.

miR-7 Reverses Breast Cancer Resistance To Chemotherapy By Targeting MRP1 And BCL2

Background

MicroRNAs (miRNAs) are a class of non‐coding RNAs that have been linked with breast cancer chemoresistance, which is a major clinical problem causing disease relapse and poor prognosis. miR-7 exerts several tumor suppressive activities.

Purpose

This study was designed to clarify whether and how miR-7 regulates breast cancer chemoresistance.

Methods

miR-7 level in breast cancer was determined by qRT-PCR analysis. Cell viability was assessed by MTS assay to quantify the IC₅₀ value of paclitaxel and carboplatin. The targets of miR-7 were confirmed by luciferase reporter assay.

Results

Higher miR-7 expression predicts better pathological complete response (pCR) of breast cancer patients receiving paclitaxel/carboplatin chemotherapy. In vitro, miR-7 sensitizes breast cancer cell lines (MCF-7 and MDA-MB-231) to paclitaxel and carboplatin, alone and in combination. In addition, we reveal that both the multidrug resistance-associated protein 1 (MRP1) and anti-apoptotic B cell lymphoma 2 (BCL2) are targets of miR-7 in breast cancer cells. Furthermore, miR-7-induced sensitization of breast cancer to paclitaxel/carboplatin is markedly reversed by restoration of MRP1 and BCL2.

Conclusion

These findings show that miR-7 reverses breast cancer chemoresistance through suppressing MRP1 and BCL2, and also suggest that miR-7 may possess a predictive value and represent a therapeutic target in breast cancer chemotherapy.

MiR-7-5p suppresses tumor metastasis of non-small cell lung cancer by targeting NOVA2

Background

Non-small cell lung cancer (NSCLC) is the leading cause of cancer mortality worldwide. Distant metastasis is thought to be one of the most important factors responsible for the failure of NSCLC therapy. MicroRNA-7-5p (miR-7-5p) has been demonstrated to be a tumor suppressor in breast cancer, hepatocarcinoma, prostate cancer and glioblastoma multiforme (GBM). However, its role in NSCLC is still not fully understood. This study evaluated the role of miR-7-5p in the progression of NSCLC and explored the underlying mechanism.

Materials & methods

The quantitative real-time PCR (qPCR), MTT, migration and invasion assays were used to evaluate the effects of miR-7-5p on the proliferation, migration and invasion of A549 and SPCA-1 cells. A tumor xenograft model was created to determine the effects of miR-7-5p on metastasis in vivo. The dual-luciferase reporter gene, neuro-oncological ventral antigen 2 (NOVA2) overexpression and western blotting assays were performed to explore the underlying mechanism.

Results

MiR-7-5p is downregulated in NSCLC tissues and lung cancer cell lines. It suppresses proliferation, migration, invasion and EMT marker expression in vitro and in vivo. Further study showed that miR-7-5p suppresses tumor metastasis of NSCLC by targeting NOVA2. Overexpression of NOVA2 attenuates the miR-7-5p-mediated inhibitory effect on lung cancer cells.

Conclusion

MiR-7-5p suppresses NSCLC metastasis. Targeting miR-7-5p may contribute to the success of NSCLC therapy.

MicroRNAs Contribute to Breast Cancer Invasiveness

Cancer statistics in 2018 highlight an 8.6 million incidence in female cancers, and 4.2 million cancer deaths globally. Moreover, breast cancer is the most frequent malignancy in females and twenty percent of these develop metastasis. This provides only a small chance for successful therapy, and identification of new molecular markers for the diagnosis and prognostic prediction of metastatic disease and development of innovative therapeutic molecules are therefore urgently required. Differentially expressed microRNAs (miRNAs) in cancers cause multiple changes in the expression of the tumorigenesis-promoting genes which have mostly been investigated in breast cancers. Herein, we summarize recent data on breast cancer-specific miRNA expression profiles and their participation in regulating invasive processes, in association with changes in cytoskeletal structure, cell-cell adhesion junctions, cancer cell-extracellular matrix interactions, tumor microenvironments, epithelial-to-mesenchymal transitions and cancer cell stem abilities. We then focused on the epigenetic regulation of individual miRNAs and their modified interactions with other regulatory genes, and reviewed the function of miRNA isoforms and exosome-mediated miRNA transfer in cancer invasiveness. Although research into miRNA’s function in cancer is still ongoing, results herein contribute to improved metastatic cancer management.

Circ_0015756 promotes proliferation, invasion and migration by microRNA-7-dependent inhibition of FAK in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) afflicts more than half a million people each year worldwide. It was reported that circ_0015756 was up-regulated in HCC, but the mechanism did not extensively studied. Methods: we collected 24 paired cancerous and noncancerous liver tissues surgically resected from HCC patients. HCC cell proliferation, invasion, migration and apoptosis in vitro were evaluated using MTT assay, Transwell assay, scratch test and Annexin-V/PI staining respectively. Interactions between circ_0015756 and miR-7, miR-7 and FAK were further validated by the luciferase reporter assay. Tumor xenografts of HCC cells with circ_0015756 knockdown were established in nude mice. Results: The expression level of circ_0015756 was increased and the expression level of miR-7 was diminished in cancerous liver tissues relative to noncancerous liver tissues. Circ_0015756 knockdown was shown to increase the expression of miR-7, reduce the proliferation, invasion, migration and resistance to apoptosis, and down-regulate the expression of FAK in HCC. We found miR-7 impaired expression of FAK to inhibit HCC cells, suggesting that miR-7 is responsible for the dysfunction of FAK. Importantly, we showed circ_0015756 could up-regulate FAK via targeting miR-7. These in vitro findings were reproduced in vivo that circ_0015756 knockdown decreased HCC xenograft growth. Conclusion: Our present study reveals a model of HCC development that is composed of circ_0015756, miR-7 and FAK. Modulation of their levels exhibits a promise in the treatment of HCC. Abbreviations: HCC: hepatocellular carcinoma; circRNAs: circular RNAs; miRNA/miR: microRNA; miR-7: microRNA-7; FAK: focal adhesion kinase; KLF-4: kruppel like factor 4; DKK1: dickkopf WNT signaling pathway inhibitor 1; ccRCC: clear cell renal cell carcinoma; PI3K: phosphoinositide 3-kinase; Ct: comparative threshold cycle; RPMI: Roswell Park Memorial Institute; FBS: fetal bovine serum; RT: reverse transcription; qPCR: quantitative polymerase chain reaction; RIPA: radioimmunoprecipitation assay; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; PVDF: polyvinylidene difluoride; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; DMSO: dimethyl sulfoxide; DMEM: Dulbecco's modified Eagle's medium; PI: propidium iodide; SPF: specific pathogen-free; SD: standard deviation; p-Akt: phosphorylated-Akt; shRNAs: small hairpin RNAs; 3'UTR: 3'-untranslated regions.

lncRNA ANRIL protects H9c2 cells against hypoxia-induced injury through targeting the miR-7-5p/SIRT1 axis

BACKGROUND

Acute myocardial infarction (AMI) occurred in the heart, which underwent long-term ischemia, and was mainly caused by hypoxia. Recently, studies have uncovered the participation of long noncoding RNAs (lncRNAs) in the pathogenesis of heart disease. Here, we planned to probe the role and molecular basis of ANRIL in hypoxia-induced H9c2 cell injury.

METHODS

Trypan blue exclusion assay and Transwell and flow cytometry assays were conducted to assess hypoxia-induced injury by determining the viability, migration, invasion, and apoptosis of H9c2 cells in different conditions, respectively. Gene expressions were evaluated by quantitative real-time polymerase chain reaction or western blot analysis as needed. RNA immunoprecipitation and luciferase reporter assays were applied to confirm the associations among genes.

RESULTS

ANRIL expression was dramatically enhanced in hypoxia-injured H9c2 cells, and silencing ANRIL aggravated hypoxia-induced H9c2 cell injury. ANRIL positively regulated sirtuin 1 (SIRT1) expression via competitively binding with miR-7-5p. Moreover, inhibition of miR-7-5p counteracted ANRIL depletion-exacerbated injury in hypoxic H9c2 cells, meanwhile, forced SIRT1 expression attenuated the injury-promoting effect of miR-7-5p upregulation on hypoxic H9c2 cells.

CONCLUSION

Our findings disclosed that ANRIL plays a protective part in hypoxia-induced H9c2 cell injury via modulating the miR-7-5p/SIRT1 axis, suggesting the great potential of ANRIL as a protective target for AMI.

microRNA-374 inhibits proliferation and promotes apoptosis of mouse melanoma cells by inactivating the Wnt signalling pathway through its effect on tyrosinase

Melanoma is one of the most malignant skin tumours with constantly increasing incidence worldwide. Previous studies have demonstrated that microRNA‐374 (miR‐374) is a novel biomarker for cancer therapy. Therefore, this study explores whether miR‐374 targeting tyrosinase (TYR) affects melanoma and its underlying mechanism. We constructed subcutaneous melanoma models to carry out the following experiments. The cells were transfected with a series of miR‐374 mimics, miR‐374 inhibitors or siRNA against TYR. Dual luciferase reporter gene assay was used for the verification of the targeting relationship between miR‐374 and TYR. Reverse transcription quantitative polymerase chain reaction and western blot analysis were conducted to determine the expression of miR‐374, TYR, β‐catenin, B‐cell leukaemia 2 (Bcl‐2), Bcl‐2 associated X protein (Bax), Low‐density lipoprotein receptor‐related protein 6 (LRP6), Leucine‐rich repeat G protein‐coupled receptor 5 (LGR5) and CyclinD1. Cell proliferation, migration, invasion, cell cycle distribution and apoptosis were evaluated using cell counting kit‐8 assay, scratch test, transwell assay and flow cytometry respectively. TYR was proved as a putative target of miR‐374 as the evidenced by the result. It was observed that up‐regulated miR‐374 or down‐regulated TYR increased expression of Bax and decreased expressions of TYR, β‐catenin, LRP6, Bcl‐2, CyclinD1 and LGR5, along with diminished cell proliferation, migration, invasion and enhanced apoptosis. Meanwhile, cells with miR‐374 inhibitors showed an opposite trend. These findings indicated that up‐regulated miR‐374 could inhibit the expression of TYR to suppress cell proliferation, migration, invasion and promote cell apoptosis in melanoma cells by inhibiting the Wnt signalling pathway.

Amplification of hsa-miR-191/425 locus promotes breast cancer proliferation and metastasis by targeting DICER1

The dysregulation of micro RNAs (miRNAs) is a crucial characteristic of human cancers. Herein, we observed frequent amplification of the MIR191/425 locus in breast cancer, which is correlated with poor survival outcome. We demonstrated that the miR-191/425 cluster binds the 3' untranslated region of the DICER1 transcript and posttranscriptionally represses DICER1 expression, thereby impairing global miRNAs biogenesis. Functionally, the forced expression of miR-191 or miR-425 stimulated the proliferation, survival, migration and invasion of breast cancer cells, whereas the inhibition of miR-191 or miR-425 suppressed these oncogenic behaviors of breast cancer cells, in a manner dependent on miR-191/425-mediated downregulation of DICER1. Furthermore, the miR-191/425 cluster promoted breast tumor growth, invasion and metastasis in vivo. The let-7 family of miRNAs was downregulated upon forced expression of miR-191 or miR-425, with a corresponding increase in the levels of let-7 target, high-mobility group AT-hook 2 (HMGA2). The forced expression of let-7 partially abrogated the miR-191/425-mediated oncogenic effects in breast cancer cells, suggestive of let-7 as a downstream effector of the miR-191/425-DICER1 axis. Collectively, we proposed that the inhibition of global miRNA processing, through miR-191/425-mediated downregulation of DICER1, promotes breast cancer progression.