miR-221/222 control luminal breast cancer tumor progression by regulating different targets

Regulation of Different Types of Cell Death by Noncoding RNAs: Molecular Insights and Therapeutic Implications

Noncoding RNAs (ncRNAs) are crucial regulatory molecules in various biological processes, despite not coding for proteins. ncRNAs are further divided into long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) based on the size of their nucleotides. These ncRNAs play crucial roles in transcriptional, post-transcriptional, and epigenetic regulation. The regulatory roles of noncoding RNAs, including lncRNAs, miRNAs, and circRNAs, are essential in various modalities of cellular death, such as apoptosis, ferroptosis, cuproptosis, pyroptosis, disulfidptosis, and necroptosis. These noncoding RNAs are integral to modulating gene expression and protein functionality during cellular death mechanisms. In apoptosis, lncRNAs, miRNAs, and circRNAs influence the transcription of apoptotic genes. In ferroptosis, these noncoding RNAs target genes and proteins involved in iron homeostasis and oxidative stress responses. For cuproptosis, noncoding RNAs regulate pathways associated with the accumulation of copper ions, leading to cellular death. During pyroptosis, noncoding RNAs modulate inflammatory mediators and caspases, affecting the proinflammatory cell death pathway. In necroptosis, noncoding RNAs oversee the formation and functionality of necrosomes, thereby influencing the balance between cellular survival and death. Disulfidptosis is a unique type of regulated cell death caused by the excessive formation of disulfide bonds within cells, leading to cytoskeletal collapse and oxidative stress, especially under glucose-limited conditions. This investigation highlights the complex mechanisms through which noncoding RNAs coordinate cellular death, emphasizing their therapeutic promise as potential targets, particularly in the domain of cancer treatment.

MiR-483 targeting integrin β4 regulates the stability of intestinal barrier in turbot (Scophthalmus maximus) during pathogen infection

The hemidesmosome, critical for epithelial cell adhesion to the basement membrane, relies on integrin beta 4 (itgb4) as a central component. Mutations of Itgb4 caused intestinal epithelial cell exfoliation in mammals, highlighting its essential role in maintaining epithelial integrity. However, the distribution and function of itgb4 in fish intestines remain poorly understood. Fish intestines, unlike those of terrestrial animals, are constantly exposed to environmental pathogens such as Vibrio anguillarum, Edwardsiella piscicida, and Aeromonas salmonicida, which can cause significant intestinal epithelial cell exfoliation and compromise mucosal barrier function. Investigating the role of itgb4 in this context is crucial for developing strategies to prevent intestinal pathogen infections in aquaculture. This study analyzed the distribution, function, and expression of itgb4 during pathogenic infection in the intestines of Scophthalmus maximus (turbot). Results revealed that Itgb4 protein is predominantly localized in intestinal epithelial cells, particularly at the cell membrane, and its expression significantly decreased during early stages of pathogenic bacterial infection. Interfering with itgb4 led to severe exfoliation of intestinal epithelial cells, accompanied by the downregulation of adhesion-related proteins and upregulation of immune-related genes. In turbot intestinal cells, itgb4 interference increased cell migration, underscoring its critical role in maintaining stable cell adhesion. Furthermore, itgb4 knockdown in zebrafish weakened intestinal epithelial cell adhesion and altered skin epithelial morphology, demonstrating its broader role in epithelial integrity. Importantly, we identified miR-483 as a key regulator of itgb4 during pathogenic infection. miR-483 exhibited an expression pattern opposite to that of itgb4. Both in vitro and in vivo experiments confirmed its role in regulating intestinal epithelial cell exfoliation by targeting itgb4. This study reveals the critical role of itgb4 in maintaining fish intestinal epithelial adhesion and its regulation by miR-483, offering new insights for improving mucosal barrier function and disease resistance in aquaculture. These findings highlight itgb4 as a potential therapeutic target to enhance disease resistance in economically important fish species.

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.

Lipoic acid alters the microRNA signature in breast cancer cells

BACKGROUND

Breast cancer, the deadliest disease affecting women globally, exhibits heterogeneity with distinct molecular subtypes. Despite advances in cancer therapy, the persistence of high mortality rates due to chemotherapy resistance remains a major challenge. Lipoic acid (LA), a natural antioxidant, has proven potent anticancer properties. Yet, the impact of LA on microRNA (miRNA) expression profile in breast cancer remains unexplored.

AIM

The aim of this study was to unravel the effect of LA on miRNA expression profiles in different breast cancer cell lines.

METHODS

The MiRCURY LNA miRNA miRNome qPCR Panel was used to compare the miRNA signature in MDA-MB-231 and MCF-7 cells treated or not with LA.

RESULTS

We identified six upregulated and six downregulated miRNAs in LA-treated MDA-MB-231 cells and 14 upregulated and four downregulated miRNAs in LA-treated MCF-7 cells compared to control cells. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis revealed that the deregulated miRNAs could alter different signaling cascades including FoxO, P53 and Hippo pathways.

CONCLUSION

The outcome of this study provides further insights into the molecular mechanisms underlying the therapeutic benefit of LA. This in turn could assist the amelioration of LA-based anticancer therapies.

Notch3 restricts metastasis of breast cancers through regulation of the JAK/STAT5A signaling pathway

PURPOSE

To explore the potential role of signal transducer and activator of transcription 5A (STAT5A) in the metastasis of breast cancer, and its mechanism of regulation underlying.

METHODS AND RESULTS

TCGA datasets were used to evaluate the expression of STAT5A in normal and different cancerous tissues through TIMER2.0, indicating that STAT5A level was decreased in breast cancer tissues compared with normal ones. Gene Set Enrichment Analysis predicted that STAT5A was associated with the activation of immune cells and cell cycle process. We further demonstrated that the infiltration of immune cells was positively associated with STAT5A level. Influorescence staining revealed the expression and distribution of F-actin was regulated by STAT5A, while colony formation assay, wound healing and transwell assays predicted the inhibitory role of STAT5A in the colony formation, migratory and invasive abilities in breast cancer cells. In addition, overexpression of the Notch3 intracellular domain (N3ICD), the active form of Notch3, resulted in the increased expression of STAT5A. Conversely, silencing of Notch3 expression by siNotch3 decreased STAT5A expression, supporting that STAT5A expression is positively associated with Notch3 in human breast cancer cell lines and breast cancer tissues. Mechanistically, chromatin immunoprecipitation showed that Notch3 was directly bound to the STAT5A promoter and induced the expression of STAT5A. Moreover, overexpressing STAT5A partially reversed the enhanced mobility of breast cancer cells following Notch3 silencing. Low expression of Notch3 and STAT5A predicted poorer prognosis of patients with breast cancer.

CONCLUSION

The present study demonstrates that Notch3 inhibits metastasis in breast cancer through inducing transcriptionally STAT5A, which was associated with tumor-infiltrating immune cells, providing a novel strategy to treat breast cancer.

Hsa-miR-221-3p promotes proliferation and migration in HER2-positive breast cancer cells by targeting LASS2 and MBD2

BACKGROUND

Human epidermal growth factor receptor (HER2)-positive breast cancers account for nearly 20% of all breast cancer cases and microRNAs (miRNAs) play crucial roles in disease progression. The study was aimed to explore the role of miR-221-3p in HER2-positive breast cancer.

METHODS

Differentially expressed miRNAs were identified by high-throughput sequencing. Quantitative real-time PCR was used to evaluate mRNA levels of corresponding genes. CKK8 and transwell assays were performed to evaluate cell viability and migration. The translation binding was assessed by luciferase assay.

RESULTS

Hsa-miR-221-3p was highly upregulated in HER2-positive breast cancer samples, particularly in patients with advanced or metastatic disease, as compared to healthy controls. miR-221-3p upregulation using mimics promoted cell proliferation and migration in HER2-positive cell lines, whereas miR-221-3p suppression had the opposite effect. Additionally, miR-221-3p mimics reduced the expression levels of LASS2 and MBD2 in HER2-positive breast cancer cells; conversely, miR-221-3p inhibition upregulated LASS2 and MBD2. miR-221-3p inhibited the translation of LASS2 and MBD2 by directly binding to their 3'-untranslated regions. Forced expression of LASS2 and MBD2 significantly attenuated the ability of miR-221-3p mimics to enhance cell growth and migration in HER2-positive but not in HER2-negative breast cancer cells. In HER-2-positive breast cancer patients, the levels of miR-221-3p were negatively correlated with the mRNA levels of LASS2 and MBD2.

CONCLUSIONS

Upregulation of hsa-miR-221-3 in HER2-positive breast cancer contributes to cancer cell proliferation and migration by directly targeting the tumor suppressors LASS2 and MBD2. Therefore, the hsa-miR-221-3 may serve as a promising and actionable therapeutic target in HER2-positive breast cancer.

Non-Coding RNAs Are Implicit in Chronic Myeloid Leukemia Therapy Resistance

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm initiated by the presence of the fusion gene BCR::ABL1. The development of tyrosine kinase inhibitors (TKIs) highly specific to p210^BCR-ABL1, the constitutively active tyrosine kinase encoded by BCR::ABL1, has greatly improved the prognosis for CML patients. Now, the survival rate of CML nearly parallels that of age matched controls. However, therapy resistance remains a persistent problem in the pursuit of a cure. TKI resistance can be attributed to both BCR::ABL1 dependent and independent mechanisms. Recently, the role of non-coding RNAs (ncRNAs) has been increasingly explored due to their frequent dysregulation in a variety of malignancies. Specifically, microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs) have been shown to contribute to the development and progression of therapy resistance in CML. Since each ncRNA exhibits multiple functions and is capable of controlling gene expression, they exert their effect on CML resistance through a diverse set of mechanisms and pathways. In most cases ncRNAs with tumor suppressing functions are silenced in CML, while those with oncogenic properties are overexpressed. Here, we discuss the relevance of many aberrantly expressed ncRNAs and their effect on therapy resistance in CML.

Microarray meta-analysis reveals IL6 and p38β/MAPK11 as potential targets of hsa-miR-124 in endothelial progenitor cells: Implications for stent re-endothelization in diabetic patients

Circulating endothelial progenitor cells (EPCs) play an important role in the repair processes of damaged vessels, favoring re-endothelization of stented vessels to minimize restenosis. EPCs number and function is diminished in patients with type 2 diabetes, a known risk factor for restenosis. Considering the impact of EPCs in vascular injury repair, we conducted a meta-analysis of microarray to assess the transcriptomic profile and determine target genes during the differentiation process of EPCs into mature ECs. Five microarray datasets, including 13 EPC and 12 EC samples were analyzed, using the online tool ExpressAnalyst. Differentially expressed genes (DEGs) analysis was done by Limma method, with an | log2FC| > 1 and FDR < 0.05. Combined p-value by Fisher exact method was computed for the intersection of datasets. There were 3,267 DEGs, 1,539 up-regulated and 1,728 down-regulated in EPCs, with 407 common DEGs in at least four datasets. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed enrichment for terms related to “AGE-RAGE signaling pathway in diabetic complications.” Intersection of common DEGs, KEGG pathways genes and genes in protein-protein interaction network (PPI) identified four key genes, two up-regulated (IL1B and STAT5A) and two down-regulated (IL6 and MAPK11). MicroRNA enrichment analysis of common DEGs depicted five hub microRNA targeting 175 DEGs, including STAT5A, IL6 and MAPK11, with hsa-miR-124 as common regulator. This group of genes and microRNAs could serve as biomarkers of EPCs differentiation during coronary stenting as well as potential therapeutic targets to improve stent re-endothelization, especially in diabetic patients.

miR-221/222 as biomarkers and targets for therapeutic intervention on cancer and other diseases: A systematic review

Among deregulated microRNAs (miRs) in human malignancies, miR-221 has been widely investigated for its oncogenic role and as a promising biomarker. Moreover, recent evidence suggests miR-221 as a fine-tuner of chronic liver injury and inflammation-related events. Available information also supports the potential of miR-221 silencing as promising therapeutic intervention. In this systematic review, we selected papers from the principal databases (PubMed, MedLine, Medscape, ASCO, ESMO) between January 2012 and December 2020, using the keywords "miR-221" and the specific keywords related to the most important hematologic and solid malignancies, and some non-malignant diseases, to define and characterize deregulated miR-221 as a valuable therapeutic target in the modern vision of molecular medicine. We found a major role of miR-221 in this view.

microRNA-221 and tamoxifen resistance in luminal-subtype breast cancer patients: A case-control study

BACKGROUND

Around 70% of breast cancers (BCs) are estrogen receptor-α (ERα)-positive. Adjuvant endocrine therapy is used to reduce estrogen levels and inhibit signal transduction through the ER. The anti-estrogen drugs that are most commonly used in endocrine therapy belong to the selective ER modulator (SERM) class and include tamoxifen. Although it has been used for three decades in cases of early-stage and ERα-positive BC, resistance to tamoxifen is a common problem. microRNAs (miRNAs) have a potential role in demonstrating BC resistance to tamoxifen therapy. Hence, there is a need to investigate the expression of miRNA-221 (miR-221) in luminal-subtype BC patients receiving tamoxifen therapy.

METHODS

This case-control study investigated luminal-subtype BC patients who had undergone endocrine therapy for at least 1 year. The case group comprised patients with local or metastatic recurrence, and the control group comprised patients without local or metastatic recurrence.

RESULTS

There was a significant difference in miR-221 expression (p = 0.005) between the case and control groups. There were no significant differences between the groups that were positive and negative for the progesterone receptor (PR) (p = 0.25), had high and low marker of proliferation Ki-67 levels (p = 0.60), were positive and negative for lymphovascular invasion (p = 0.14), and had stage 2 and stage 3 cancer (p = 0.25).

CONCLUSION

miR-221 expression was higher in tamoxifen-resistant BC cases. miR-221 is a potential biomarker of tamoxifen resistance.

Noncoding RNAs in tumor metastasis: molecular and clinical perspectives

Metastasis is the main culprit of cancer-associated mortality and involves a complex and multistage process termed the metastatic cascade, which requires tumor cells to detach from the primary site, intravasate, disseminate in the circulation, extravasate, adapt to the foreign microenvironment, and form organ-specific colonization. Each of these processes has been already studied extensively for molecular mechanisms focused mainly on protein-coding genes. Recently, increasing evidence is pointing towards RNAs without coding potential for proteins, referred to as non-coding RNAs, as regulators in shaping cellular activity. Since those first reports, the detection and characterization of non-coding RNA have explosively thrived and greatly enriched the understanding of the molecular regulatory networks in metastasis. Moreover, a comprehensive description of ncRNA dysregulation will provide new insights into novel tools for the early detection and treatment of metastatic cancer. In this review, we focus on discussion of the emerging role of ncRNAs in governing cancer metastasis and describe step by step how ncRNAs impinge on cancer metastasis. In particular, we highlight the diagnostic and therapeutic applications of ncRNAs in metastatic cancer.

MicroRNA-221 regulates cell activity and apoptosis in acute lymphoblastic leukemia via regulating PTEN

T cell acute lymphoblastic leukemia (T-ALL), an aggressive and heterogeneous malignancy originating from T cell precursors (thymocytes), accounts for ~15% of all ALL cases in children and for ~25% in adults. The present study aimed to investigate the role of microRNA-221 (miR-221) in the regulation of cell viability and apoptosis of human T-ALL cells and its related regulatory mechanisms. To perform this investigation, miR-221 was upregulated or knocked down in human T-ALL cells (Jurkat cells) using miR-221 mimic or inhibitor, respectively. Then, cell viability was determined using a 3-(4,5-dimethylthiahiazol-2-y1)-2,5-diphenytetrazolium bromide assay, cell invasion and migration were analyzed via Transwell assays, and cell apoptosis was detected using flow cytometry. It was found that transfection with a miR-221 inhibitor significantly inhibited Jurkat cell viability, migration and invasion, and induced Jurkat cell apoptosis. Whereas, transfection with the miR-221 mimic resulted in the opposite effects. Besides, the results showed that phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was a target of miR-221. Moreover, it was observed that the effects of the miR-221 inhibitor on Jurkat cell viability, migration and invasion, and cell apoptosis were significantly eliminated by PTEN-small interfering RNA. In addition, it was shown that the phosphatidylinositol 3-kinase/AKT pathway was involved in the effect of miR-221 on Jurkat cells. In conclusion, the data indicated that miR-221 existed as an oncogene in T-ALL, and its downregulation could inhibit the development of ALL by targeting PTEN. Therefore, miR-221 may be a novel potential therapeutic target for ALL.

MicroRNAs: The Link between the Metabolic Syndrome and Oncogenesis

Metabolic syndrome (MetS) represents a cluster of disorders that increase the risk of a plethora of conditions, in particular type two diabetes, cardiovascular diseases, and certain types of cancers. MetS is a complex entity characterized by a chronic inflammatory state that implies dysregulations of adipokins and proinflammatory cytokins together with hormonal and growth factors imbalances. Of great interest is the implication of microRNA (miRNA, miR), non-coding RNA, in cancer genesis, progression, and metastasis. The adipose tissue serves as an important source of miRs, which represent a novel class of adipokines, that play a crucial role in carcinogenesis. Altered miRs secretion in the adipose tissue, in the context of MetS, might explain their implication in the oncogenesis. The interplay between miRs expressed in adipose tissue, their dysregulation and cancer pathogenesis are still intriguing, taking into consideration the fact that miRNAs show both carcinogenic and tumor suppressor effects. The aim of our review was to discuss the latest publications concerning the implication of miRs dysregulation in MetS and their significance in tumoral signaling pathways. Furthermore, we emphasized the role of miRNAs as potential target therapies and their implication in cancer progression and metastasis.

Regulatory MicroRNAs in T2DM and Breast Cancer

MicroRNAs orchestrate the tight regulation of numerous cellular processes and the deregulation in their activities has been implicated in many diseases, including diabetes and cancer. There is an increasing amount of epidemiological evidence associating diabetes, particularly type 2 diabetes mellitus, to an elevated risk of various cancer types, including breast cancer. However, little is yet known about the underlying molecular mechanisms and even less about the role miRNAs play in driving the tumorigenic potential of the cell signaling underlying diabetes pathogenesis. This article reviews the role of miRNA in bridging the diabetes–breast cancer association by discussing specific miRNAs that are implicated in diabetes and breast cancer and highlighting the overlap between the disease-specific regulatory miRNA networks to identify a 20-miRNA signature that is common to both diseases. Potential therapeutic targeting of these molecular players may help to alleviate the socioeconomic burden on public health that is imposed by the type 2 diabetes mellitus (T2DM)–breast cancer association.

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.

MicroRNA-221 and MicroRNA-222 in Common Human Cancers: Expression, Function, and Triggering of Tumor Progression as a Key Modulator

MicroRNAs (miRNAs) are a class of short (~22 nucleotides [nt]), single-stranded RNA oligonucleotides that are regulatory in nature and are often dysregulated in various diseases, including cancer. miRNAs can act as oncomiRs (miRNAs associated with cancer) or tumor suppressor miRNAs and have the potential to be a diagnostic, prognostic, noninvasive biomarker for these diseases. MicroRNA-221 (miR-221) and microRNA-222 (miR-222) are homologous miRNAs, located on the human chromosome Xp11.3, which factored significantly in impairment in the regulation of a wide range of cancers. In this review, we have highlighted the most consistently reported dysregulated miRNAs that trigger human tissues to express cancerous features and surveyed the role of those miRNAs in metastasis, apoptosis, angiogenesis, and tumor prognosis. Also, we applied the causes of drug resistance and the role of coordinated actions of these miRNAs to epigenetic changes and selected miRNAs as a potential type of cancer treatment.

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.

Identification of microRNA clusters cooperatively acting on epithelial to mesenchymal transition in triple negative breast cancer

MicroRNAs play important roles in many biological processes. Their aberrant expression can have oncogenic or tumor suppressor function directly participating to carcinogenesis, malignant transformation, invasiveness and metastasis. Indeed, miRNA profiles can distinguish not only between normal and cancerous tissue but they can also successfully classify different subtypes of a particular cancer. Here, we focus on a particular class of transcripts encoding polycistronic miRNA genes that yields multiple miRNA components. We describe 'clustered MiRNA Master Regulator Analysis (ClustMMRA)', a fully redesigned release of the MMRA computational pipeline (MiRNA Master Regulator Analysis), developed to search for clustered miRNAs potentially driving cancer molecular subtyping. Genomically clustered miRNAs are frequently co-expressed to target different components of pro-tumorigenic signaling pathways. By applying ClustMMRA to breast cancer patient data, we identified key miRNA clusters driving the phenotype of different tumor subgroups. The pipeline was applied to two independent breast cancer datasets, providing statistically concordant results between the two analyses. We validated in cell lines the miR-199/miR-214 as a novel cluster of miRNAs promoting the triple negative breast cancer (TNBC) phenotype through its control of proliferation and EMT.

Microcystin-LR promotes migration via the cooperation between microRNA-221/PTEN and STAT3 signal pathway in colon cancer cell line DLD-1

Previous researches have reported that microcystin-LR (MC-LR) contributes to the progression of multiple types of carcinomas including colon cancer; however, the underlying molecular mechanisms remain unclear and require in-depth investigation. Here, the colon cell line DLD-1 was arranged for the analysis by the microRNA microarray which was associated with the cancer metastasis after MC-LR exposure. 31 human microRNAs were differentially expressed, including miR-221, which targeted 3'-UTR of PTEN mRNA and PTEN level was down-regulated by MC-LR treatment. Besides, MC-LR also induced the phosphorylation of STAT3, which can be reversed by adding miR-221 inhibitor and PTEN expression plasmid. Furthermore, miR-221 inhibitor, STAT3 siRNA and PTEN expression plasmid could reverse the effects of MC-LR induced migration with the accumulation of β-catenin in nuclei. In conclusion, our study suggested that MC-LR promoted the progression of colon carcinoma, at least in part, by regulating the expression miR-221, PTEN and STAT3 phosphorylation, which offers a novel perspective to understand the connection between MC-LR and colon cancer.

MicroRNA-221 sensitizes chronic myeloid leukemia cells to imatinib by targeting STAT5

MicroRNAs (miRNAs) are involved in various processes from the development to drug resistance of tumors, including chronic myeloid leukemia (CML). In this study, we examined the STAT5-related miRNA-expression profile in CML cell lines (K562 and imatinib-resistant K562/G) by quantitative real-time reverse-transcriptase polymerase chain reactions. MiR-221 expression was markedly decreased in K562/G cells and peripheral blood mononuclear cells from patients with treatment failure, when compared to imatinib-sensitive CML cells and patients with optimal responses respectively. We also observed the expression of STAT5 inversely correlated with miR-221 expression in K562 and KBM5 cells. Additionally, STAT5 was validated as a direct target of miR-221 in dual-luciferase reporter vector assays. MiR-221 restoration and STAT5 knockdown in K562/G cells increased the sensitivity of CML cells to imatinib by reducing the Bcl2: Bax ratio. Collectively, our data suggested that miR-221-STAT5 axis played crucial roles in controlling the sensitivity of CML cells to imatinib.

Estradiol-mediated regulation of hepatic iNOS in obese rats: Impact of Src, ERK1/2, AMPKα, and miR-221

PURPOSE

This study aimed to investigate in vivo effects of estradiol on the regulation of hepatic inducible nitric oxide synthase (iNOS) expression in the high fat (HF) diet-induced obesity. Also, we aimed to investigate whether activation of the extracellular signal-regulated kinase (ERK1/2), adenosine monophosphate-activated protein kinase (AMPK), Src kinase, and miR-221 is involved in estradiol-mediated regulation of iNOS in the liver of obese male Wistar rats. Male Wistar rats were fed a standard laboratory diet or a HF diet for 10 weeks. Half of HF rats were treated with estradiol intraperitoneally (40 μg/kg), whereas the other half were placebo-treated 24 H before euthanasia. Results show that estradiol treatment of HF rats decreased hepatic iNOS mRNA (P < 0.05) and protein expression (P < 0.01), the protein levels of p65 subunit of nuclear factor κB (P < 0.05) and ERα (P < 0.05), ERK1/2 phosphorylation (P < 0.001), and ERα/Src kinase association (P < 0.05). By contrast, hepatic Src protein level (P < 0.05), AMPKα phosphorylation (P < 0.05), and miR-221 expression (P < 0.05) were increased in HF rats after estradiol treatment. Our results indicate that estradiol in vivo regulates hepatic iNOS expression in obese rats via molecular mechanisms involving ERK1/2, AMPK, Src, and miR-221 signaling.

New emerging roles of microRNAs in breast cancer

BACKGROUND

MicroRNAs constitute a large family of non-coding RNAs, which actively participate in tumorigenesis by regulating a set of mRNAs of distinct signaling pathways. An altered expression of these molecules has been found in different tumorigenic processes of breast cancer, the most common type of cancer in the female population worldwide.

PURPOSE

The objective of this review is to discuss how miRNAs become master regulators in breast tumorigenesis.

METHODS

An integrative review of miRNAs and breast cancer literature from the last 5 years was done on PubMed. We summarize recent works showing that the defects on the biogenesis of miRNAs are associated with different breast cancer characteristics. Then, we show several examples that demonstrate the link between cellular processes regulated by miRNAs and the hallmarks of breast cancer. Finally, we examine the complexity in the regulation of these molecules as they are modulated by other non-coding RNAs and the clinical applications of miRNAs as they could serve as good diagnostic and classification tools.

CONCLUSION

The information presented in this review is important to encourage new directed studies that consider microRNAs as a good tool to improve the diagnostic and treatment alternatives in breast cancer.

Changes in miR-221/222 Levels in Invasive and In Situ Carcinomas of the Breast: Differences in Association with Estrogen Receptor and TIMP3 Expression Levels

BACKGROUND

Breast cancer (BC) is a heterogeneous group of diseases that still represents a major cause of death in the female population. MicroRNAs (miRNAs, miRs), such as miR-221 and miR-222, have been shown to be involved in BC pathology by acting via its target genes such as tissue inhibitor of metalloproteinase 3 (TIMP3).

OBJECTIVES

The main goals of this study were to find differences in miR-221/222 levels of expression in BC groups based on invasiveness, and to investigate the association with estrogen receptor (ER), TIMP3 messenger RNA (mRNA) levels, and clinicopathological characteristics of patients and tumors.

METHODS

In this study, we measured levels of miR-221/222 in 63 breast tissue samples by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) using TaqMan® technology and immunohistochemistry.

RESULTS

miR-221/222 levels varied significantly across groups based on invasiveness (P < 0.001). In in situ tumors, miR-221 and miR-222 were negatively associated with ER (P = 0.001, r = -0.714, and P = 0.013, r = -0.585, respectively). In invasive breast carcinomas associated with non-invasive tumors, miR-222 was inversely associated with ER (P = 0.039, r = -0.620). Pure invasive BCs showed a positive correlation of miR-221 and miR-222 with TIMP3 mRNA levels (P = 0.008, r = 0.508, and P = 0.010, r = 0.497, respectively).

CONCLUSION

An increase in miR-221/222 might be an important event for in situ carcinoma formation, and miR-221/222 may be important molecules that highlight potential differences between invasive breast carcinomas associated with non-invasive and pure invasive BCs.

Stem Cell-Derived, microRNA-Carrying Extracellular Vesicles: A Novel Approach to Interfering with Mesangial Cell Collagen Production in a Hyperglycaemic Setting

Extracellular vesicles (EVs) that are derived from stem cells are proving to be promising therapeutic options. We herein investigate the therapeutic potential of EVs that have been derived from different stem cell sources, bone-marrow (MSC) and human liver (HLSC), on mesangial cells (MCs) exposed to hyperglycaemia. By expressing a dominant negative STAT5 construct (ΔNSTAT5) in HG-cultured MCs, we have demonstrated that miR-21 expression is under the control of STAT5, which translates into Transforming Growth Factor beta (TGFβ) expression and collagen production. A number of approaches have been used to show that both MSC- and HLSC-derived EVs protect MCs from HG-induced damage via the transfer of miR-222. This resulted in STAT5 down-regulation and a decrease in miR-21 content, TGFβ expression and matrix protein synthesis within MCs. Moreover, we demonstrate that changes in the balance between miR-21 and miR-100 in the recipient cell, which are caused by the transfer of EV cargo, further contribute to providing beneficial effects. Interestingly, these effects were only detected in HG-cultured cells. Finally, it was found that HG reduced the expression of the nuclear encoded mitochondrial electron transport chain (ETC) components, CoxIV. It is worth noting that EV administration can rescue CoxIV expression in HG-cultured MCs. These results thus demonstrate that both MSC- and HLSC-derived EVs transfer the machinery needed to preserve MCs from HG-mediated damage. This occurs via the horizontal transfer of functional miR-222 which directly interferes with damaging cues. Moreover, our data indicate that the release of EV cargo into recipient cells provides additional therapeutic advantages against harmful mitochondrial signals.

New Concepts in Cancer Biomarkers: Circulating miRNAs in Liquid Biopsies

The effective and efficient management of cancer patients relies upon early diagnosis and/or the monitoring of treatment, something that is often difficult to achieve using standard tissue biopsy techniques. Biological fluids such as blood hold great possibilities as a source of non-invasive cancer biomarkers that can act as surrogate markers to biopsy-based sampling. The non-invasive nature of these “liquid biopsies” ultimately means that cancer detection may be earlier and that the ability to monitor disease progression and/or treatment response represents a paradigm shift in the treatment of cancer patients. Below, we review one of the most promising classes of circulating cancer biomarkers: microRNAs (miRNAs). In particular, we will consider their history, the controversy surrounding their origin and biology, and, most importantly, the hurdles that remain to be overcome if they are really to become part of future clinical practice.

RETRACTED: miR-221/222 enhance the tumorigenicity of human breast cancer stem cells via modulation of PTEN/Akt pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concerns were raised in the public domain and also reported by the authors to the journal regarding the similarity between various panels from Figures 2 and 3. Given also the institutional investigation, the journal requested the authors to provide the raw data. However, the authors were not able to provide raw data of sufficient quality and detail for the journal to independently audit the provenance and validity of the data, and therefore the Editor-in-Chief decided to retract the article.

Identification of lung cancer miRNA-miRNA co-regulation networks through a progressive data refining approach

Co-regulations of miRNAs have been much less studied than the research on regulations between miRNAs and their target genes, although these two problems are equally important for understanding the entire mechanisms of complex post-transcriptional regulations. The difficulty to construct a miRNA-miRNA co-regulation network lies in how to determine reliable miRNA pairs from various resources of data related to the same disease such as expression levels, gene ontology (GO) databases, and protein-protein interactions. Here we take a novel integrative approach to the discovery of miRNA-miRNA co-regulation networks. This approach can progressively refine the various types of data and the computational analysis results. Applied to three lung cancer miRNA expression data sets of different subtypes, our method has identified a miRNA-miRNA co-regulation network and co-regulating functional modules common to lung cancer. An example of these functional modules consists of genes SMAD2, ACVR1B, ACVR2A and ACVR2B. This module is synergistically regulated by let-7a/b/c/f, is enriched in the same GO category, and has a close proximity in the protein interaction network. We also find that the co-regulation network is scale free and that lung cancer related miRNAs have more synergism in the network. According to our literature survey and database validation, many of these results are biologically meaningful for understanding the mechanism of the complex post-transcriptional regulations in lung cancer.

miR-221 facilitates the TGFbeta1-induced epithelial-mesenchymal transition in human bladder cancer cells by targeting STMN1

Background

Distant metastasis is the major cause of cancer-related death, and epithelial-to-mesenchymal transition (EMT) has a critical role in this process. Accumulating evidence indicates that EMT can be regulated by microRNAs (miRNAs). miR-221, as oncogenes in several human cancers, was significantly up-regulated in bladder cancers. However, the role of miR-221 in the progression of bladder cancer metastasis remains largely unknown.

Methods

We used qRT-PCR and western blot to accurately measure the levels of miR-221, STMN1 and EMT markers in TGFβ1 induced EMT of bladder cancer cells. miR-221 inhibitors were re-introduced into bladder cancer cells to investigate its role on tumor metastasis which was measured by MTT, wound healing, transwell invasion and adherent assays. Luciferase reporter assay was used to reveal the target gene of miR-221.

Results

miR-221 expression was greatly increased by TGFβ1 in bladder cancer cell. miR-221 inhibition reversed TGFβ1 induced EMT by sharply increasing the expression of the epithelial marker E-cadherin and decreasing the expression of the mesenchymal markers vimentin, Fibroactin and N-cadherin. Furthermore, miR-221 expression is positively correlated with malignant potential of bladder cancer cell through promoting loss of cell adhesion and prometastatic behavior. Luciferase reporter assay revealed that miR-221 negatively regulates STMN1 expression by direct targeting to the 3′UTR region of STMN1.

Conclusions

Our study demonstrated that miR-221 facilitated TGFβ1-induced EMT in human bladder cancer cells by targeting STMN1 and represented a promising therapeutic target in the process of metastasis.

Comprehensive expression analysis of miRNA in breast cancer at the miRNA and isomiR levels

Breast cancer (BC) is the main factor that leads cause of cancer death in women worldwide. A class of small non-coding RNAs, microRNAs (miRNAs), has been widely studied in human cancers as crucial regulatory molecule. Recent studies indicate that a series of isomiRs can be yielded from a miRNA locus, and these physiological miRNA isoforms have versatile roles in miRNA biogenesis. Herein, we performed a comprehensive analysis of miRNAs at the miRNA and isomiR levels in BC using next-generation sequencing data from The Cancer Genome Atlas (TCGA). Abnormally expressed miRNA (miR-21, miR-221, miR-155, miR-30e and miR-25) and isomiR profiles could be obtained at the miRNA and isomiR levels, and similar biological roles could be detected. IsomiR expression profiles should be further concerned, and especially isomiRs are actual regulatory molecules in the miRNA-mRNA regulatory networks. The study provides a comprehensive expression analysis at the miRNA and isomiR levels in BC, which indicates biological roles of isomiRs.

Expression patterns of miR-221 and its target Caspase-3 in different cancer cell lines

Caspases are important initiators and most well-known finishers of apoptosis. By changing the death propagation homeostatic equilibrium, their different expression patterns might trigger the progression of hazardous diseases like cancer. miR-221 is an oncogenic miRNA. It is known to have both anti-angiogenic and angiogenic effect. The aim of this work was to compare the expression levels of miR-221 and its target caspase-3 in different cancer cell lines and to find out a relationship between these two. We also tried to establish a prominent relationship between miR-221 and its role in apoptosis by studying their expression levels. Our results indicate that expression of caspase-3 is quite lower as compared to miR-221 expression in all of the selected cancer cell lines. As a result, we conclude that miR-221 may have a crucial role in repressing the expression of caspase-3 which may contribute to a lower apoptotic rate, thus supporting the selection of more aggressive cancer cells. To our knowledge, this is the first study related to the expression levels of caspase-3 and miR-221 in different cell lines at the same time. We expect that our study might pave the way for better understanding the role of miR-221 in apoptotic regulation of caspase-3.