miR-660-5p promotes breast cancer progression through down-regulating TET2 and activating PI3K/AKT/mTOR signaling

TET Enzymes and 5hmC Levels in Carcinogenesis and Progression of Breast Cancer: Potential Therapeutic Targets

Breast Cancer (BC) was the most common female cancer in incidence and mortality worldwide in 2020. Similarly, BC was the top female cancer in the USA in 2022. Risk factors include earlier age at menarche, oral contraceptive use, hormone replacement therapy, high body mass index, and mutations in BRCA1/2 genes, among others. BC is classified into Luminal A, Luminal B, HER2-like, and Basal-like subtypes. These BC subtypes present differences in gene expression signatures, which can impact clinical behavior, treatment response, aggressiveness, metastasis, and survival of patients. Therefore, it is necessary to understand the epigenetic molecular mechanism of transcriptional regulation in BC, such as DNA demethylation. Ten-Eleven Translocation (TET) enzymes catalyze the oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) on DNA, which in turn inhibits or promotes the gene expression. Interestingly, the expression of TET enzymes as well as the levels of the 5hmC epigenetic mark are altered in several types of human cancers, including BC. Several studies have demonstrated that TET enzymes and 5hmC play a key role in the regulation of gene expression in BC, directly (dependent or independent of DNA de-methylation) or indirectly (via interaction with other proteins such as transcription factors). In this review, we describe our recent understanding of the regulatory and physiological function of the TET enzymes, as well as their potential role as biomarkers in BC biology.

TET protein inhibitors: Potential and limitations

TET proteins (methylcytosine dioxygenases) play an important role in the regulation of gene expression. Dysregulation of their activity is associated with many serious pathogenic states such as oncological diseases. Regulation of their activity by specific inhibitors could represent a promising therapeutic strategy. Therefore, this review describes various types of TET protein inhibitors in terms of their inhibitory mechanism and possible applicability. The potential and possible limitations of this approach are thoroughly discussed in the context of TET protein functionality in living systems. Furthermore, possible therapeutic strategies based on the inhibition of TET proteins are presented and evaluated, especially in the field of oncological diseases.

Whole blood miRNAs in relapsing MS patients treated with dimethyl fumarate in the phase 4 TREMEND trial

We investigated the impact of dimethyl fumarate (DMF), an oral therapy for relapsing multiple sclerosis (MS), on blood microRNA (miRNA) signatures and neurofilament light (NFL) levels. DMF normalized miR-660-5p and modulated various miRNAs associated with the NF-kB pathway. These alterations reached a peak 4-7 months after treatment. Notably, particular miRNAs correlated with high or low NFL levels, implying their potential role as markers of treatment efficacy. Our findings broaden the understanding of DMF's immunomodulatory effects and may aid in predicting treatment responses.

microRNA-660 Enhances Cisplatin Sensitivity via Decreasing SATB2 Expression in Lung Adenocarcinoma

Increasing evidence suggests that microRNAs' (miRNAs) abnormal expression is one of the main factors of chemotherapy resistance in various cancers. However, the role of miRNAs in lung adenocarcinoma (LUAD) resistance to cisplatin is still unclear. In this study, we analyzed a microarray dataset to investigate miRNAs related to cisplatin resistance in LUAD. The expression of miRNAs in LUAD tissues and cell lines was detected using real-time quantitative polymerase chain reaction (RT-qPCR). Special AT-Rich Sequence-Binding Protein 2 (SATB2) in LUAD cell lines was detected using RT-qPCR and Western blot. Cell proliferation was measured by CCK8 and colony formation assays, while cell cycle and apoptosis were measured by flow cytometry. A dual-luciferase reporter assay was performed to confirm that SATB2 is a target gene of microRNA-660 (miR-660). We showed that the expression of miR-660 was not only decreased in LUAD cells and tissues but also further decreased in the cisplatin-resistant A549 cell line. The overexpression of miR-660 increased cisplatin sensitivity in LUAD cells. In addition, we identified SATB2 as a direct target gene of miR-660. We also revealed that miR-660 increased cisplatin sensitivity in LUAD cells via targeting SATB2. In conclusion, miR-660/SATB2 axis is a key regulator of cisplatin resistance in LUAD.

miRNA dysregulation in traumatic brain injury and epilepsy: a systematic review to identify putative biomarkers for post-traumatic epilepsy

Traumatic brain injury (TBI) leads to post-traumatic epilepsy (PTE); hence, both TBI and PTE share various similar molecular mechanisms. MicroRNA (miRNA) is a small noncoding RNA that acts as a gene-silencing molecule. Notably, the dysregulation of miRNAs in various neurological diseases, including TBI and epilepsy, has been reported in several studies. However, studies on commonly dysregulated miRNAs and the regulation of shared pathways in both TBI and epilepsy that can identify potential biomarkers of PTE are still lacking. This systematic review covers the peer-review publications of TBI and database studies of epilepsy-dysregulated miRNAs of clinical studies. For TBI, 290 research articles were identified after screening, and 12 provided data for dysregulated miRNAs in humans. The compiled data suggest that 85 and 222 miRNAs are consecutively dysregulated in TBI and epilepsy. In both, 10 miRNAs were found to be commonly dysregulated, implying that they are potentially dysregulated miRNAs for PTE. Furthermore, the targets and involvement of each putative miRNA in different pathways were identified and evaluated. Additionally, clusters of predicted miRNAs were analyzed. Each miRNA's regulatory role was linked with apoptosis, inflammation, and cell cycle regulation pathways. Hence, these findings provide insight for future diagnostic biomarkers.

A Breast Cancer Prediction Model Based on a Panel from Circulating Exosomal miRNAs

Breast cancer (BC) has been a serious threat to women's health. Exosomes contain a variety of biomolecules, which is an excellent choice as disease diagnostic markers, but whether it could be applied as a noninvasive biomarker for BC diagnosis demands to be additional studied. In this study, we aimed at creating a predictive model and reveal the value of plasma exosomal miRNA (exo-miRNA) in early diagnosis of BC. Firstly, exosomes isolated from plasma were identified by Nanoparticle Tracking Analysis (NTA), Transmission Electron Microscope (TEM), and Western Blot. miRNA expression in plasma samples from 56 BC patients and 40 normal controls was analyzed by high-throughput sequencing. miRNAs with strong correlation characteristics were selected by Lasso logistic regression. Then, we built the training set and test set, evaluated the Lasso regression accuracy, and evaluated the performance of different models in the training set and test set. Finally, GO analysis, KEGG, and Reactome pathway enrichment analysis were used to understand the biological significance of 16 characteristic miRNAs. The successful separation of exosomes in serum was identified by NTA, TEM, and Western Blot. The training set data matrix containing 1962 miRNAs was obtained by sequencing for model construction, and 16 strongly correlated miRNAs were selected by Lasso logistic regression. The accuracy of Lasso regression in training set and test set were 97.22% and 95.83%, respectively. We built different models and evaluated the performance of each model in the training set and test set. The results showed that the AUC values of Lasso, SVM, GBDT, and Random Forest model in the training set were 1, and the AUC values in the test set were 0.979, 0.936, 0.971, and 0.979, respectively. Bioinformatics analysis showed that 16 signature miRNAs were significantly enriched in cancer-related pathways such as herpes simplex virus 1 infection, TGF-β signaling, and Toll-like receptor family. The results of this study suggest that the 16 characteristic miRNAs screened from plasma exosomes can be used as a group of biomarkers, and the prediction model constructed based on this set of markers is expected to be used in the early diagnosis of BC.

Small biomarkers with massive impacts: PI3K/AKT/mTOR signalling and microRNA crosstalk regulate nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumours of the head and neck in Southeast Asia and southern China. The Phosphatidylinositol 3-kinase/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signalling pathway is involved in processes related to tumour initiation/progression, such as proliferation, apoptosis, metastasis, and drug resistance, and is closely related to the clinicopathological features of NPC. In addition, key genes involved in the PI3K/AKT/mTOR signalling pathway undergo many changes in NPC. More interestingly, a growing body of evidence suggests an interaction between this signalling pathway and microRNAs (miRNAs), a class of small noncoding RNAs. Therefore, in this review, we discuss the interactions between key components of the PI3K/AKT/mTOR signalling pathway and various miRNAs and their importance in NPC pathology and explore potential diagnostic biomarkers and therapeutic targets.

Circular RNA_0006014 promotes breast cancer progression through sponging miR-885-3p to regulate NTRK2 and PIK3/AKT pathway

Breast cancer is the most common cancer in women worldwide. Numerous reports have demonstrated that circRNAs play an essential role in regulating the biological characteristics of breast cancer. However, there are currently no reports regarding the role of hsa_circ_0006014 in breast cancer. In this study, qRT-PCR was used to detect the expression of hsa_circ_0006014 and related genes. MTT, colony formation and Transwell assays were used to explore the potential biological functions of hsa_circ_0006014 in breast cancer cells. Western blotting was used to explore the potential molecular mechanisms involving hsa_circ_0006014. In vivo experiments were used to evaluate the influence of hsa_circ_0006014 on animal tumors. In this study, we found higher expression of hsa_circ_0006014 in breast tumor samples than in matched adjacent normal samples, and its expression was positively correlated with histological grade (grade iii). Phenotypically, hsa_circ_0006014 promoted the proliferation of MDA-MB-231 and MCF-7 breast cancer cells. Mechanistically, there were confirmed binding sites between hsa_circ_0006014 and miR-885-3p, and hsa_circ_0006014 promoted breast cancer cell proliferation partially by sponging miR-885-3p and influenced CDK2/CCNE1 and CDK4/6/CCND1. Furthermore, we found that hsa_circ_0006014 regulated NTRK2 through miR-885-3p to modulate the PIK3/AKT signaling pathway. Our results demonstrated that hsa_circ_0006014 promotes breast cancer progression by sponging miR-885-3p to regulate the NTRK2/PIK3CA/AKT axis.

Tumor-promoting mechanisms of macrophage-derived extracellular vesicles-enclosed microRNA-660 in breast cancer progression

INTRODUCTION

Breast cancer metastasis is the main cause of cancer-related death in women worldwide. Current therapies have remarkably improved the prognosis of breast cancer patients but still fail to manage metastatic breast cancer. Here, the present study was set to explore the role of microRNA (miR)-660 from tumor-associated macrophages (TAMs) in breast cancer, particularly in metastasis.

MATERIALS AND METHODS

We collected breast cancer tissues and isolated their polarized macrophages as well as extracellular vesicles (EVs), in which we measured the expression of miR-660, Kelch-like Protein 21 (KLHL21), and nuclear factor-κB (NF-κB) p65. Breast cancer cells were transfected with miR-660 mimic, miR-660 inhibitor, and sh-KLHL21 and then the cells were co-cultured with EVs or TAMs followed by detection of invasion and migration. Finally, mouse model of breast cancer was established to detect the effect of miR-660 or KLHL21 on metastasis by measuring the lymph node metastasis (LNM) foci in femur and lung.

RESULTS

KLHL21 was poorly expressed, whereas miR-660 was highly expressed in breast cancer tissues and cells. Of note, low KLHL21 expression or high miR-660 expression was related to poor overall survival. EVs-contained miR-660 was identified to bind to KLHL21, reducing the binding between KLHL21 and inhibitor kappa B kinase β (IKKβ) to activate the NF-κB p65 signaling pathway. Interestingly, EV-loaded miR-660 from TAMs could be internalized by breast cancer cells. Moreover, silencing of KLHL21 increased the number of lung LNM foci in vivo, while EVs-contained miR-660 promoted cancerous cell invasion and migration.

DISCUSSION

Taken altogether, our work shows that TAMs-EVs-shuttled miR-660 promotes breast cancer progression through KLHL21-mediated IKKβ/NF-κB p65 axis.

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

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

Circ_SEC61A1 contributes to the progression of multiple myeloma cells via regulating miR-660-5p/CDK6 axis

BACKGROUND

Circular RNAs (circRNAs) have been reported to play critical roles in the malignant progression of diverse human cancers, including multiple myeloma (MM). This study aimed to explore the functional role and underlying mechanism of circ_SEC61A1 in MM progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) assay was performed to detect the expression levels of circ_SEC61A1, microRNA (miR)-660-5p and cyclin-dependent kinase 6 (CDK6) mRNA. The localization of circ_SEC61A1 in MM cells was tested by the subcellular fractionation location assay. Actinomycin D assay was conducted to determine the characteristics of circ_SEC61A1. Cell proliferation was evaluated by colony formation assay, 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay and 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Western blot assay was exploited to examine the expression of proteins. Cell migration and invasion were tested via transwell assay, and cell apoptosis was measured by flow cytometry analysis. Dual-luciferase reporter assay was utilized to confirm the interaction between miR-660-5p and circ_SEC61A1 or CDK6.

RESULTS

Circ_SEC61A1 level was increased in MM tissues and cells. Circ_SEC61A1 was a stable circRNA and mainly located in cytoplasm. Circ_SEC61A1 silence restrained the proliferation, metastasis and expedited the apoptosis in MM cells. CDK6 was identified as the target of miR-660-5p, and circ_SEC61A1 sponged miR-660-5p to positively regulate CDK6 expression. The inhibitory impacts of circ_SEC61A1 knockdown on the progression of MM cells were mitigated by miR-660-5p inhibition. MiR-660-5p overexpression blocked the malignant phenotypes of MM cells by targeting CDK6.

CONCLUSION

Our study manifested that circ_SEC61A1 could accelerate MM progression at least partially through modulating miR-660-5p/CDK6 axis.

miR-660-5p-loaded M2 macrophages-derived exosomes augment hepatocellular carcinoma development through regulating KLF3

OBJECTIVE

M2 macrophages (M2) can affect tumor development by secreting various cytokines, including exosomes (Exo). Herein, we intended to explore how microRNA (miR)-660-5p-modified M2-Exo affected hepatocellular carcinoma (HCC) development through regulating Kruppel-like factor 3 (KLF3).

METHODS

miR-660-5p and KLF3 levels were first measured in clinical HCC tissues. A miR-targeted relation was explored between miR-660-5p and KLF3. M2-Exo were modified by miR-660-5p-related oligonucleotides and co-cultured with HepG2 cells to determine their effects on cell proliferation, colony formation, invasion, migration, apoptosis and epithelial-mesenchymal transition (EMT). Xenografted tumors were collected from mice to further verify the in vitro results.

RESULTS

Higher miR-660-5p and lower KLF3 levels were examined in HCC. KLF3 was targeted by miR-660-5p. Up-regulated miR-660-5p-modified M2-Exo boosted the grwoth and EMT of HepG2 cells, but this effect was impaired by overexpression of KLF3. miR-660-5p-loaded M2-Exo enhanced tumorigenic ability of HCC cells in mice. On the contrary, down-regulated miR-660-5p reduced M2-Exo-mediated promotion of growth of HCC cells in vitro and in vivo.

CONCLUSION

Our study summarizes that miR-660-5p-loaded M2-Exo augment HCC development through down-regulating KLF3.

The Potential Equivalents of TET2 Mutations

Simple Summary

In acute myeloid leukemia (AML) TET2 mutations have been observed to be mutually exclusive with IDH1, IDH2, and WT1 mutations, all of them showing a similar impact on the transcription profile. Because of this, it is possible that TET2/IDH1/2/WT1 mutated AML could be considered as having similar characteristics between each other. Nonetheless, other genes also interact with TET2 and influence its activity. Because of this, it is possible that other signatures exist that would mimic the effect of TET2 mutations. Thus, in this review, we searched the literature for the genes that were observed to interact with TET2 and classified them in the following manner: transcription alteration, miRs, direct interaction, posttranslational changes, and substrate reduction.

Abstract

TET2 is a dioxygenase dependent on Fe²⁺ and α-ketoglutarate which oxidizes 5-methylcytosine (5meC) to 5-hydroxymethylcytosine (5hmeC). TET proteins successively oxidize 5mC to yield 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). Among these oxidized methylcytosines, 5fC and 5caC are directly excised by thymine DNA glycosylase (TDG) and ultimately replaced with unmethylated cytosine. Mutations in TET2 have been shown to lead to a hypermethylated state of the genome and to be responsible for the initiation of the oncogenetic process, especially in myeloid and lymphoid malignancies. Nonetheless, this was also shown to be the case in other cancers. In AML, TET2 mutations have been observed to be mutually exclusive with IDH1, IDH2, and WT1 mutations, all of them showing a similar impact on the transcription profile of the affected cell. Because of this, it is possible that TET2/IDH1/2/WT1 mutated AML could be considered as having similar characteristics between each other. Nonetheless, other genes also interact with TET2 and influence its effect, thus making it possible that other signatures exist that would mimic the effect of TET2 mutations. Thus, in this review, we searched the literature for the genes that were observed to interact with TET2 and classified them in the following manner: transcription alteration, miRs, direct interaction, posttranslational changes, and substrate reduction. What we propose in the present review is the potential extension of the TET2/IDH1/2/WT1 entity with the addition of certain expression signatures that would be able to induce a similar phenotype with that induced by TET2 mutations. Nonetheless, we recommend that this approach be taken on a disease by disease basis.