CircRNA circFOXK2 facilitates oncogenesis in breast cancer via IGF2BP3/miR-370 axis

The emerging role and mechanism of HMGA2 in breast cancer

High mobility group AT-hook 2 (HMGA2) is a member of the non-histone chromosomal high mobility group (HMG) protein family, which participate in embryonic development and other biological processes. HMGA2 overexpression is associated with breast cancer (BC) cell growth, proliferation, metastasis, and drug resistance. Furthermore, HMGA2 expression is positively associated with poor prognosis of patients with BC, and inhibiting HMGA2 signaling can stimulate BC cell progression and metastasis. In this review, we focus on HMGA2 expression changes in BC tissues and multiple BC cell lines. Wnt/β-catenin, STAT3, CNN6, and TRAIL-R2 proteins are upstream mediators of HMGA2 that can induce BC invasion and metastasis. Moreover, microRNAs (miRNAs) can suppress BC cell growth, invasion, and metastasis by inhibiting HMGA2 expression. Furthermore, long noncoding RNAs (LncRNAs) and circular RNAs (CircRNAs) mainly regulate HMGA2 mRNA and protein expression levels by sponging miRNAs, thereby promoting BC development. Additionally, certain small molecule inhibitors can suppress BC drug resistance by reducing HMGA2 expression. Finally, we summarize findings demonstrating that HMGA2 siRNA and HMGA2 siRNA-loaded nanoliposomes can suppress BC progression and metastasis.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

circ-TFRC downregulation suppresses ovarian cancer progression via miR-615-3p/IGF2 axis regulation

BACKGROUND

Ovarian cancer (OC) is a malignancy among female globally. Circular RNAs (circRNAs) are a family of circular endogenous RNAs generated from selective splicing, which take part in many traits. Former investigation suggested that circ-TFRC was abnormally expressed in breast cancer (BC). Further, the role of circ-TFRC to the progress of OC remains unclear. So, the aim of this study was to reveal the regulatory mechanism of circ-TFRC.

METHODS

Our team made the luciferase reporter assay to validate circ-TFRC downstream target. Transwell migration assay, 5-ethynyl-20-deoxyuridine, and cell counting kit-8 were applied to investigate both proliferation and migration. In vivo tumorigenesis and metastasis assays were performed to investigate the circ-TFRC role in OC.

RESULTS

The outputs elucidated that circ-TFRC expression incremented in OC cells and tissues. circ-TFRC downregulation inhibited OC cell proliferation as well as migration in in vivo and in vitro experiments. The luciferase results validated that miR-615-3p and IGF2 were circ-TFRC downstream targets. IGF2 overexpression or miR-615-3p inhibition reversed OC cell migration after circ-TFRC silencing. Also, IGF2 overexpression reversed OC cell migration and proliferation post miR-615-3p upregulation.

CONCLUSION

Results demonstrate that circ-TFRC downregulation inhibits OC progression and metastasis via IGF2 expression regulation and miR-615-3psponging.

Comprehensive analysis of circRNA expression profiles in postmenopausal women differing in bone mineral density

Postmenopausal osteoporosis (PMOP) seriously endangers the bone health of older women. Although there are currently indicators to diagnose PMOP, early diagnostic biomarkers are lacking. Circular ribonucleic acid (circRNA) has a stable structure, regulates gene expression, participates in the pathological process of disease, and has the potential to become a biomarker. The purpose of this study was to investigate circRNAs that could be used to predict patients with early PMOP. Ribonucleic acid (RNA) sequencing was performed on peripheral blood leukocytes from 15 female patients to identify differential circRNAs between different groups. Using bioinformatics analysis, enrichment analysis was performed to discover relevant functions and pathways. CircRNA-micro ribonucleic acid (miRNA) interaction analysis and messenger ribonucleic acid (mRNA) prediction and network construction help us to understand the relationship between circRNA, miRNA, and mRNA. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the gene expression of candidate circRNAs. We screened out 2 co-expressed differential circRNAs, namely hsa_circ_0060849 and hsa_circ_0001394. By analyzing the regulatory network, a total of 54 miRNAs and 57 osteoporosis-related mRNAs were identified, which, as potential downstream target genes of hsa_circ_0060849 and hsa_circ_0001394, may play a key role in the occurrence and development of PMOP. The occurrence and development of PMOP is regulated by circRNAs, and hsa_circ_0060849 and hsa_circ_0001394 can be used as new diagnostic markers and therapeutic targets for early PMOP.

MiR-485-3p/MiR-543/MiR-337-3p is Required for the Oncogenic Potential of the Hsa_circ_0007385-MEMO1 Axis in Colorectal Cancer

Circular RNAs (circRNAs) play regulatory roles in the biological processes of multiple tumors, colorectal cancer (CRC) included. Our previous study probed the impact of circ_0007385 on CRC cell malignant behaviors, while the underlying mechanism remains obscure. In this work, the potential mechanism of hsa_circ_0007385 in CRC was probed. Functional experiments were implemented for probing the function of hsa_circ_0007385 in CRC. Further analysis revealed the relation between hsa_circ_0007385 and miRNAs. A xenograft mouse model was implemented for probing the influence of hsa_circ_0007385 on CRC growth and metastasis in vivo. Hsa_circ_0007385 was up-regulated in CRC. Hsa_circ_0007385 positively regulated its host gene mediator of cell motility 1 (MEMO1). Hsa_circ_0007385 silencing inhibited CRC progression. Hsa_circ_0007385 and MEMO1 bond to miR-485-3p/miR-543/miR-337-3p, and these three miRNAs were lowly expressed in CRC, and negatively modulated by hsa_circ_0007385. Hsa_circ_0007385 functioned as an oncogene in CRC in a miR-485-3p/miR-543/miR-337-3p- or MEMO1-dependent manner. Hsa_circ_0007385 promoted CRC progression via modulating miR-485-3p/miR-543/miR-337-3p/MEMO1 axis. Thus, circ-MEMO1 might be a promising therapeutic target for CRC.

Targeting insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs) for the treatment of cancer

Insulin-like growth factor 2 mRNA-binding proteins (IMPs, IGF2BPs) are RNA-binding proteins that regulate a variety of biological processes. In recent years, several studies have found that IGF2BPs play multiple roles in various biological processes, especially in cancer, and speculated on their mechanism of anticancer effect. In addition, targeting IGF2BPs or their downstream target gene has also received extensive attention as an effective treatment for different types of cancer. In this review, we summarized the recent progress on the role of IGF2BPs in cancers and their structural characteristics. We focused on describing the development of inhibitors targeting IGF2BPs and the prospects for further applications.

Circular RNA-mediated miRNA sponge & RNA binding protein in biological modulation of breast cancer

Circular RNAs (circRNAs) and small non-coding RNAs of the head-to-junction circle in the construct play critical roles in gene regulation and are significantly associated with breast cancer (BC). Numerous circRNAs are potential cancer biomarkers that may be used for diagnosis and prognosis. Widespread expression of circRNAs is regarded as a feature of gene expression in highly diverged eukaryotes. Recent studies show that circRNAs have two main biological modulation models: sponging and RNA-binding. This review explained the biogenesis of circRNAs and assessed emerging findings on their sponge function and role as RNA-binding proteins (RBPs) to better understand how their interaction alters cellular function in BC. We focused on how sponges significantly affect the phenotype and progression of BC. We described how circRNAs exercise the translation functions in ribosomes. Furthermore, we reviewed recent studies on RBPs, and post-protein modifications influencing BC and provided a perspective on future research directions for treating BC.

Downregulated circRNA_CDKN1A promotes gallbladder cancer progression through activation of the NF-κB pathway

This study uncovered the potential clinical value and molecular driving mechanisms of circular RNAs (circRNAs) in gallbladder cancer (GBC). Differentially expressed circRNAs in GBC cells were screened by high-throughput sequencing. CircRNA_CDKN1A (circBase ID: hsa_circ_0076194) was knocked out in BGC-SD cells through transfection with sh-circRNA_CDKN1A. Then, proliferation was investigated via CCK8 and EdU assays, apoptosis via flow cytometry, migration via wound healing assays, and invasion via Transwell assays. Bioinformatics analysis of circRNA_CDKN1A-related signaling pathways was performed using MetScape and g:Profiler. Results showed that the knockdown of circRNA_CDKN1A enhanced the proliferation, migration, and invasion of GBC cells and inhibited apoptosis. In addition, knocking out circRNA_CDKN1A promoted GBC cell proliferation and enhanced the dry indices of the OCT4 protein and CD34 expression levels. The knockdown of circRNA_CDKN1A activated the epithelial-mesenchymal transition pathway. Bioinformatics analysis revealed that the biological role of circRNA_CDKN1A in GBC cells involved the NF-κB pathway. LY2409881, which is an NF-κB inhibitor, reversed the effects induced by the knockdown of circRNA_CDKN1A in GBC-SD cells. In summary, the knockdown of circRNA_CDKN1A promoted the progression of GBC by activating the NF-κB signaling pathway. For the first time, this study revealed the mechanism of circRNA_CDKN1A-mediated regulatory action in GBC and identified the newly discovered circRNA_CDKN1A-NF-κB signaling axis as a potentially important candidate for clinical therapy and prognostic diagnosis of GBC.

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

Hypoxia increases the biogenesis of IGF2BP3-bound circular RNAs

BACKGROUND

Insulin-like Growth Factor 2 Binding Protein 3 (IGF2BP3) promotes cancer migration and invasion by binding to several coding and non-coding RNAs. Hypoxia stimulates tumor progression by upregulating Hypoxia Inducible Factors and downstream signaling. Quaking (QKI) gene, which is upregulated in hypoxia and promotes epithelial to mesenchymal transition (EMT), induces circular RNAs. Therefore, the axis between IGF2BP3, QKI, circular RNAs and their respective host genes under hypoxia was studied.

METHODS AND RESULTS

Several IGF2BP3-bound circular RNAs were previously identified in HepG2. There were 13 circRNAs originating from 8 host genes bound to IGF2BP3. We confirmed their binding to IGF2BP3 in U87MG using an RNA Immunoprecipitation assay. MALAT1, an oncogenic lncRNA was also found to be associated with IGF2BP3. Three adherent cell lines expressing high levels of IGF2BP3 viz., HeLa, HepG2 and U87MG were cultured under normoxia (20%O2) and hypoxia (<0.2%O2) for 48-168 h. Expression of IGF2BP3, QKI, EMT markers, IGF2BP3-bound circRNAs and their host mRNAs expression were assessed by quantitative real-time PCR (qRT-PCR) in both normoxia and hypoxia. The hypoxia markers viz., VEGF and CA9 were upregulated in all the cell lines in hypoxia at all time points along with an increase in SNAIL. We found 6 genes, viz., PHC3, CDYL, ANKRD17, ARID1A, NEIL3 and FNDC3B with increased expression both at the mRNA and circRNA level indicating their synergistic role in tumor initiation. Overall, we found that circRNA to mRNA expression was observed to be increased for most of the genes and time points of hypoxia in all the cell lines. IGF2BP3 and QKI were also upregulated in hypoxia indicating their role in circRNA biogenesis and stability.

CONCLUSION

Our data implies that hypoxia augments circRNA biogenesis which might subsequently play a role in tumor progression.

Exosomal circRNAs in gastrointestinal cancer: Role in occurrence, development, diagnosis and clinical application (Review)

Gastrointestinal cancer is frequently detected at an advanced stage and has an undesirable prognosis due to the absence of efficient and precise biomarkers and therapeutic targets. Exosomes are small, living‑cell‑derived vesicles that serve a critical role in facilitating intercellular communication by transporting molecules from donor cells to receiver cells. circular RNAs (circRNAs) are mis‑expressed in a variety of diseases, including gastrointestinal cancer, and are promising as diagnostic biomarkers and tumor therapeutic targets for gastrointestinal cancer. The main features of exosomes and circRNAs are discussed in the present review, along with research on the biological function of exosomal circRNAs in the development and progression of gastrointestinal cancer. It also assesses the advantages and disadvantages of implementing these findings in clinical applications.

The Circular RNA circFOXK2 Enhances the Tumorigenesis of Non-Small Cell Lung Cancer Through the miR-149-3p/IL-6 Axis

Circular RNAs (circRNAs) are the non-coding types of RNAs and are thoughts to be linked with human cancer progression. circFOXK2 is believed to be associated with cancers, however, the molecular mechanisms of circFOXK2 in non-small cell lung cancer (NSCLC) are still unclear. Here we firstly reported that circFOXK2 enhances the tumorigenesis of NSCLC through the miR-149-3p/IL-6 axis. The expression of circFOXK2, microRNA-149-3p (miR-149-3p) and IL-6 were assessed by qRT-PCR and western blot. Transwell, colony formation, wound healing, and CCK-8 assays were used to elucidate NSCLC cells' proliferation, migration, and invasion. MiR-149-3p interaction with circFOXK2 was confirmed by dual-luciferase reporter gene assay (DLRGA). Furthermore, the biological effect of circFOXK2 on NSCLC progression was detected by tumor xenograft assay. CircFOXK2 were upregulated in NSCLC tissues and cells, miR-149-3p were downregulated in NSCLC tissues and cells. In addition, circFOXK2 stimulated NSCLC cell proliferation, migration and invasion in vitro. Mechanical analysis indicated that circFOXK2 modulated IL-6 via miR-149-3p sponging. Furthermore, circFOXK2 overexpression promoted tumor growth in vivo. Overall, this research verified that circFOXK2 enhances the tumorigenesis of NSCLC through the miR-149-3p/IL-6 axis.

MiR-103a-3p Promotes Tumorigenesis of Breast Cancer by Targeting ETNK1

Background

We aimed to elucidate the molecular mechanism of miR-103a-3p regulating breast cancer progression.

Methods

Firstly, clinical tissues was obtained from 2019-2023 at Yancheng Third People's Hospital, Yancheng, China. miR-103a-3p or ETNK1 expression in clinical tissues or breast cancer cell lines was analyzed with qRTPCR. MDA-MB-231 cells were performed with miR-103a-3p inhibitor or mimic, and OE-ETNK1. The proliferation and apoptosis ability were detected by CCK-8 and TUNEL assay. The xenograft models were established by inoculating transfected MDA-MB-231 cells to BALB/c mice.

Results

miR-103a-3p showed an overexpression and was related to poor prognosis in breast cancer. miR-103a-3p-deprived MDA-MB-231 cells displayed weaker levels of cell proliferation and higher rates of apoptosis. In contrast, ETNK1 was downregulated in breast cancer and proved to be a downstream target of miR-103a-3p. Xenograft models subjected to either miR-103a-3p antagomir treatment or ETNK1-knockdown resulted in tumor growth suppression.

Conclusion

miR-103a-3p might promote breast cancer progression by inhibiting ETNK1.

Circ_0071589 contributes to growth, angiogenesis, and metastasis of colorectal cancer through regulating miR-296-5p/EN2 axis

To explore the function and regulation mechanism of circ_0071589 in colorectal cancer (CRC). The expression levels of circ_0071589, microRNA-296-5p (miR-296-5p), and Engrailed-2 (EN2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was performed to check the protein levels of EN2 and apoptosis-related proteins. Cell colony formation and 5-Ethynyl-29-deoxyuridine (EdU) assay were used to exhibit cell proliferation. Cell apoptosis was shown by flow cytometry. Tube formation assay manifested the angiogenesis ability of CRC cells. Transwell assay demonstrated cell migration and invasion. The interaction between miR-296-5p and circ_0071589 or EN2 was identified by dual-luciferase reporter assay. The effect of circ_0071589 on tumor formation was demonstrated by in vivo tumor formation experiments. Immunohistochemical (IHC) assay was used to detect the positive cell rate of Ki67 in tumor tissue. Circ_0071589 was upregulated in CRC tissue and cells. Circ_0071589 knockdown repressed CRC cells proliferation, angiogenesis, migration, invasion, and promoted cell apoptosis. MiR-296-5p was downregulated in CRC tissue and cells. And miR-296-5p inhibitor could reverse the malignant phenotypes and angiogenesis inhibition of CRC cells caused by circ_0071589 knockdown. Additionally, miR-296-5p decreased CRC cell colony formation, EdU-positive cells, angiogenesis, and increased cell apoptosis through reducing the expression level of EN2. Finally, circ_0071589 silencing inhibited tumor formation in vivo. Circ_0071589 upregulated EN2 expression through sponging miR-296-5p, thereby promoting the malignant phenotype and angiogenesis of CRC cells, which provided a new target for the treatment of CRC.

IGF2BP3-EGFR-AKT axis promotes breast cancer MDA-MB-231 cell growth

Insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) is an emerging prognostic indicator, and its elevated expression correlates with malignancy in a broad spectrum of cancers. However, its regulatory networks have not yet been reported. In this study, we identified the regulatory targets of IGF2BP3 in breast cancer MDA-MB-231 cells using RNA immunoprecipitation sequencing (RIP-seq) and high-throughput RNA-sequencing (RNA-seq). We discovered that these targets were enriched in the inflammatory response, endoplasmic reticulum stress, cell cycle, and cancer-related pathways, providing a new perspective for better understanding the functional mechanisms of IGF2BP3. Moreover, we identified that the epidermal growth factor receptor (EGFR), a downstream target, is regulated by IGF2BP3. IGF2BP3 binds to and protects EGFR mRNA from degradation and facilitates cell proliferation via the EGFR/AKT pathway in MDA-MB-231 cells. In addition, IGF2BP3 expression was robust and could not be altered by stimulation with EGF and anti-EGFR siRNA or EGFR signaling pathway inhibitors (gefitinib, LY294002 and SL-327). These results demonstrate that IGF2BP3, as a stubborn oncogene, promotes triple-negative breast cancer MDA-MB-231 cell proliferation by strengthening the role of the EGFR-AKT axis.

Exploring the roles and molecular mechanisms of RNA binding proteins in the sorting of noncoding RNAs into exosomes during tumor progression

BACKGROUND

RNA binding proteins (RBPs) play a role in sorting non-coding RNAs (ncRNAs) into exosomes. These ncRNAs, carried by exosomes, are involved in regulating various aspects of tumor progression, including metastasis, angiogenesis, control of the tumor microenvironment, and drug resistance. Recent studies have emphasized the importance of the RBP-ncRNA-exosome mechanism in tumor regulation.

AIM OF REVIEW

This comprehensive review aims to explore the RBP-ncRNA-exosome mechanism and its influence on tumor development. By understanding this intricate mechanism provides novel insights into tumor regulation and may lead to innovative treatment strategies in the future.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The review discusses the formation of exosomes and the complex relationships among RBPs, ncRNAs, and exosomes. The RBP-ncRNA-exosome mechanism is shown to affect various aspects of tumor biology, including metastasis, multidrug resistance, angiogenesis, the immunosuppressive microenvironment, and tumor progression. Tumor development relies on the transmission of information between cells, with RBPs selectively mediating sorting of ncRNAs into exosomes through various mechanisms, which in turn carry ncRNAs to regulate RBPs. The review also provides an overview of potential therapeutic strategies, such as targeted drug discovery and genetic engineering for modifying therapeutic exosomes, which hold great promise for improving cancer treatment.

circSLCO1B7 suppresses the malignant progression of hepatocellular carcinoma via the miR-556-3p/DAB2IP axis

Circular RNAs (circRNAs) are noncoding RNAs with a circular colsed structure that play an important role in the occurrence and development of cancers. The functional mechanism of circRNAs as ceRNAs in hepatocellular carcinoma (HCC) and its effect on the invasion and metastasis of HCC need to be further studied. Five pairs of HCC tissues were selected for high-throughput sequencing, and 19 circRNAs with differential expression were obtained. The expression of circSLCO1B7 was obviously downregulated in 50 pairs of tumor tissues and plasma of HCC patients, which was closely related to the TNM stage, lymph node metastasis and tumor size. Cell functional experiments showed that circSLCO1B7 could inhibit cell growth, migration, invasion and promote cell apoptosis. In the regulatory mechanism, circSLCO1B7 sponged miR-556-3p to regulate the expression of the downstream target gene DAB2IP and induced the Epithelial-mesenchymal transition (EMT) progression. Our results indicated that circSLCO1B7 significantly inhibits the metastasis of HCC via the miR-556-3p/DAB2IP axis. Thus, circSLCO1B7 is a good candidate as a therapeutic target.

Deciphering the Functional Status of Breast Cancers through the Analysis of Their Extracellular Vesicles

Breast cancer (BC) accounts for the highest incidence of tumor-related mortality among women worldwide, justifying the growing search for molecular tools for the early diagnosis and follow-up of BC patients under treatment. Circulating extracellular vesicles (EVs) are membranous nanocompartments produced by all human cells, including tumor cells. Since minimally invasive methods collect EVs, which represent reservoirs of signals for cell communication, these particles have attracted the interest of many researchers aiming to improve BC screening and treatment. Here, we analyzed the cargoes of BC-derived EVs, both proteins and nucleic acids, which yielded a comprehensive list of potential markers divided into four distinct categories, namely, (i) modulation of aggressiveness and growth; (ii) preparation of the pre-metastatic niche; (iii) epithelial-to-mesenchymal transition; and (iv) drug resistance phenotype, further classified according to their specificity and sensitivity as vesicular BC biomarkers. We discuss the therapeutic potential of and barriers to the clinical implementation of EV-based tests, including the heterogeneity of EVs and the available technologies for analyzing their content, to present a consistent, reproducible, and affordable set of markers for further evaluation.

Circular RNA ATP2C1 (has_circ_0005797) sponges miR-432/miR-335 to promote breast cancer progression through regulating CCND1 expression

Breast cancer (BC) is the most frequently diagnosed malignancy in the world. Accumulating evidence has indicated that circular RNAs (circRNAs) play essential roles in BC. Here we investigated the biological functions of circATP2C as a competing endogenous RNA (ceRNA) in BC development. We found that circATP2C1 expression was upregulated in BC cells and tissues and was significantly associated with the poor overall survival in BC patients. CircATP2C1 is more resistant to RNase R exonuclease and Actinomycin D than is the linear mRNA of ATP2C1. CircATP2C1-knockdown inhibited the viability, colony proliferation and invasion abilities, while increasing the apoptosis rates of BC cells in vitro, as well as inhibiting tumor mass, size and weight in vivo. Upregulation of miR-432 and miR-335 inhibited CCND1 expression in BC cells. Both miR-432/miR-335 specifically bind to the 3'-UTR of circATP2C1 and CCND1 (CyclinD1). The inhibition of the aggression of BC cells by circATP2C1-knockdown was rescued by co-transfection of miR-432/miR-335 inhibitors. In conclusion, circATP2C1 promotes BC oncogenesis and metastasis by sponging miR-432/miR-335 to abolish the inhibition of the target gene, CCND1. This study suggests that circATP2C1 has implications for BC diagnosis and treatment.

Physcion increases the sensitivity of hepatocellular carcinoma to sorafenib through miRNA-370/PIM1 axis-regulated glycolysis

BACKGROUND

Resistance to sorafenib has become a challenge in clinical treatment of hepatocellular carcinoma (HCC). Physcion is a common bioactive anthraquinone that has potential as an anticancer agent.

AIM

To study the effect of physcion on sensitizing HCC cells to sorafenib.

METHODS

Sorafenib-resistant HCC cells were established and treated with sorafenib and/or physcion. The cell viability, proliferation and apoptosis were measured by cell counting kit-8, colony formation, flow cytometry, and in vivo xenograft model. Glucose uptake, lactate acid production, extracellular acidification rate (ECAR), and oxygen consumption rate (OCR) were measured to analyze glycolysis. Expression of glycolysis-related regulators was assessed by western blotting.

RESULTS

The addition of physcion significantly enhanced the antitumor effects of sorafenib on sorafenib-resistant HCC cells, manifested by enhanced apoptosis and suppressed cell growth. The glucose uptake, lactate acid production, and ECAR were elevated, and OCR was suppressed by physcion treatment. The level of PIM1 was elevated and miR-370 was suppressed in sorafenib-resistant HCC cells compared with the parental cells, which was suppressed by physcion treatment. Inhibition of miR-370 notably reversed the effects of physcion on sorafenib-resistant HCC cells.

CONCLUSION

Our data indicated that physcion enhanced the sensitivity of HCC cells to sorafenib by enhancing miR-370 to suppress PIM1-promoted glycolysis.

Targeting IGF2BP3 in Cancer

RNA-binding proteins (RBPs) can regulate multiple pathways by binding to RNAs, playing a variety of functions, such as localization, stability, and immunity. In recent years, with the development of technology, researchers have discovered that RBPs play a key role in the N6-methyladenosine (m6A) modification process. M6A methylation is the most abundant form of RNA modification in eukaryotes, which is defined as methylation on the sixth N atom of adenine in RNA. Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) is one of the components of m6A binding proteins, which plays an important role in decoding m6A marks and performing various biological functions. IGF2BP3 is abnormally expressed in many human cancers, often associated with poor prognosis. Here, we summarize the physiological role of IGF2BP3 in organisms and describe its role and mechanism in tumors. These data suggest that IGF2BP3 may be a valuable therapeutic target and prognostic marker in the future.

The Tumorigenic Role of Circular RNA-MicroRNA Axis in Cancer

Circular RNAs (circRNAs) are a class of endogenous RNAs that control gene expression at the transcriptional and post-transcriptional levels. Recent studies have increasingly demonstrated that circRNAs act as novel diagnostic biomarkers and promising therapeutic targets for numerous cancer types by interacting with other non-coding RNAs such as microRNAs (miRNAs). The miRNAs are presented as crucial risk factors and regulatory elements in cancer by regulating the expression of their target genes. Some miRNAs are derived from transposable elements (MDTEs) that can transfer their location to another region of the genome. Genetic interactions between miRNAs and circular RNAs can form complex regulatory networks with various carcinogenic processes that play critical roles in tumorigenesis and cancer progression. This review focuses on the biological regulation of the correlative axis among circular RNAs, miRNAs, and their target genes in various cancer types and suggests the biological importance of MDTEs interacting with oncogenic or tumor-suppressive circRNAs in tumor progression.

m6A readers, writers, erasers, and the m6A epitranscriptome in breast cancer

Epitranscriptomic modification of RNA regulates human development, health, and disease. The true diversity of the transcriptome in breast cancer including chemical modification of transcribed RNA (epitranscriptomics) is not well understood due to limitations of technology and bioinformatic analysis. N-6-methyladenosine (m6A) is the most abundant epitranscriptomic modification of mRNA and regulates splicing, stability, translation, and intracellular localization of transcripts depending on m6A association with reader RNA-binding proteins. m6A methylation is catalyzed by the METTL3 complex and removed by specific m6A demethylase ALKBH5, with the role of FTO as an 'eraser' uncertain. In this review, we provide an overview of epitranscriptomics related to mRNA and focus on m6A in mRNA and its detection. We summarize current knowledge on altered levels of writers, readers, and erasers of m6A and their roles in breast cancer and their association with prognosis. We summarize studies identifying m6A peaks and sites in genes in breast cancer cells.

CircEML1 facilitates the steroid synthesis in follicular granulosa cells of chicken through sponging gga-miR-449a to release IGF2BP3 expression

Non-coding RNAs (ncRNAs) induced competing endogenous RNAs (ceRNA) play crucial roles in various biological process by regulating target gene expression. However, the studies of ceRNA networks in the regulation of ovarian ovulation processing of chicken remains deficient compared to that in mammals. Our present study revealed that circEML1 was differential expressed in hen's ovarian tissues at different ages (15 W/20 W/30 W/68 W) and identified as a loop structure from EML1 pre-mRNA, which promoted the expressions of CYP19A1/StAR and E2/P4 secretion in follicular granulosa cells (GCs). Furthermore, circEML1 could serve as a sponge of gga-miR-449a and also found that IGF2BP3 was targeted by gga-miR-449a to co-participate in the steroidogenesis, which possibly act the regulatory role via mTOR/p38MAPK pathways. Meanwhile, in the rescue experiment, gga-miR-449a could reverse the promoting role of circEML1 to IGF2BP3 and steroidogenesis. Eventually, this study suggested that circEML1/gga-miR-449a/IGF2BP3 axis exerted an important role in the steroidogenesis in GCs of chicken.

circRNAs and their relationship with breast cancer: a review

BACKGROUND

Recently, an increasing number of studies have been conducted on circular RNAs (circRNAs) that have demonstrated their different roles in a variety of biological processes. Moreover, a large number of circRNAs have been shown to be involved in the occurrence and development of breast cancer (BC).

MAIN BODY

Both functional and mechanistic experiments have shown that circular RNAs (circRNAs) can act as competing endogenous RNAs by sponging miRNAs, encoding proteins, and regulating parental genes. In doing so, circRNAs modulate the proliferation, migration, apoptosis, and invasion of BC cells in vitro as well as tumor growth and metastasis in vivo. Moreover, scores of circRNAs have been demonstrated to be related to clinicopathological features, prognosis, and treatment sensitivity in patients with BC; many circRNAs have shown potential as biomarkers for diagnosis, drug sensitivity, and prognosis prediction. Furthermore, researchers have focused on circRNAs as potential therapeutic targets.

CONCLUSION

In this review, we briefly summarize the functions and categories of circRNAs, their different roles in BC, and recent research and therapeutic progress related to circRNAs.

Breast Cancer-Delivered Exosomal miRNA as Liquid Biopsy Biomarkers for Metastasis Prediction: A Focus on Translational Research with Clinical Applicability

Metastasis represents the most important cause of breast cancer-associated mortality. Even for early diagnosed stages, the risk of metastasis is significantly high and predicts a grim outcome for the patient. Nowadays, efforts are made for identifying blood-based biomarkers that could reliably distinguish patients with highly metastatic cancers in order to ensure a closer follow-up and a more personalized therapeutic method. Exosomes are nano vesicles secreted by cancer cells that can transport miRNAs, proteins, and other molecules and deliver them to recipient cells all over the body. Through this transfer, cancer cells modulate their microenvironment and facilitate the formation of the pre-metastatic niche, leading to sustained progression. Exosomal miRNAs have been extensively studied due to their promising potential as prognosis biomarkers for metastatic breast cancer. In this review, we tried to depict an overview of the existing literature regarding exosomal miRNAs that are already validated as potential biomarkers, and which could be immediately available for the clinic. Moreover, in the last section, we highlighted several miRNAs that have proven their function in preclinical studies and could be considered for clinical validation. Considering the lack of standard methods for evaluating exosomal miRNA, we also discussed the challenges and the technical aspects underlying this issue.

CircPDSS1 promotes the proliferation, invasion, migration, and EMT of breast cancer cell via regulating miR-320c/CKAP5 axis

Background

Breast cancer (BC) poses serious threats to women’s health. A large number of reports have proved that circular RNAs (circRNAs) exert vital functions in human cancers, including BC.

Methods

The function of circPDSS1 in BC cells was tested by CCK-8, colony formation, TUNEL, transwell-invasion, wound healing, and IF assays. RNA pull down, luciferase reporter and RIP assays were employed to verify the relationship among circPDSS1, miR-320c and CKAP5.

Results

CircPDSS1 was upregulated in BC cells, and circPDSS1 knockdown repressed BC cell malignant behaviors. Further, circPDSS1 was found to bind to miR-320c in BC cells, and miR-320c overexpression suppressed malignant processes of BC cells. MiR-320c could also bind to CKAP5. Moreover, miR-320c inhibition increased the level of CKAP5, but circPDSS1 downregulation decreased the level of CKAP5. Finally, rescue experiments indicated that CKAP5 knockdown countervailed the promoting effect of miR-320c inhibition on the malignant behaviors of circPDSS1-depleted BC cells.

Conclusions

CircPDSS1 promotes proliferation, invasion, migration as well as EMT of BC cells by modulating miR-320c/CKAP5 axis. Our finding may be useful for researchers to find new potential therapeutic or diagnostic targets for BC.

Spotlight on Exosomal Non-Coding RNAs in Breast Cancer: An In Silico Analysis to Identify Potential lncRNA/circRNA-miRNA-Target Axis

Breast cancer (BC) has recently become the most common cancer type worldwide, with metastatic disease being the main reason for disease mortality. This has brought about strategies for early detection, especially the utilization of minimally invasive biomarkers found in various bodily fluids. Exosomes have been proposed as novel extracellular vesicles, readily detectable in bodily fluids, secreted from BC-cells or BC-tumor microenvironment cells, and capable of conferring cellular signals over long distances via various cargo molecules. This cargo is composed of different biomolecules, among which are the novel non-coding genome products, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and the recently discovered circular RNA (circRNA), all of which were found to be implicated in BC pathology. In this review, the diverse roles of the ncRNA cargo of BC-derived exosomes will be discussed, shedding light on their primarily oncogenic and additionally tumor suppressor roles at different levels of BC tumor progression, and drug sensitivity/resistance, along with presenting their diagnostic, prognostic, and predictive biomarker potential. Finally, benefiting from the miRNA sponging mechanism of action of lncRNAs and circRNAs, we established an experimentally validated breast cancer exosomal non-coding RNAs-regulated target gene axis from already published exosomal ncRNAs in BC. The resulting genes, pathways, gene ontology (GO) terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis could be a starting point to better understand BC and may pave the way for the development of novel diagnostic and prognostic biomarkers and therapeutics.

Circular RNA circ_0005835 promotes promoted neural stem cells proliferation and differentiate to neuron and inhibits inflammatory cytokines levels through miR-576-3p in Alzheimer's disease

Alzheimer's disease (AD) is the most frequent neurodegenerative disease and it is difficult to have an effective and simple method for AD early diagnosis. CircRNAs (circular RNAs) are novel discovered non-coding endogenous RNAs that affect cell apoptosis, differentiation, growth, metabolism, and metastasis. Recently, it has reported that circ_0005835 was one upregulated circRNA in the AD patients. However, the function role of circ_0005835 remains unknown. In our study, we found that circ_0005835 was upregulated in AD patients and cell models. Knockdown of circ_0005835 could downregulate neuroinflammation in BV2 cells. Moreover, knockdown of circ_0005835 promoted neural stem cells (NSC) proliferation and differentiate to neuron. These data mean that circ_0005835 plays important role in the development of AD. The miR-576-3p expression in serum was downregulated in the AD group compared to the health control group. Consistently, the level of circ_0005835 was overexpressed in the Aβ-treated in both SH-SY5Y and BV2 cells. Moreover, the expression of miR-576-3p was negatively correlated with circ_0005835 in AD patients. In addition, we performed the rescued experiments to show that knockdown of circ_0005835 could downregulate neuroinflammation through sponging miR-576-3p in BV2 cells. Inhibition of circ_0005835 promoted NSC proliferation and differentiate to neuron via sponging miR-576-3p. These data suggested that circ_0005835 promoted AD development through regulating miR-576-3p expression.

CircFOXK2 enhances tumorigenesis and immune evasion in non-small cell lung cancer by miR-485-5p/PD-L1 axis

BACKGROUND

Circular RNAs (circRNAs) serve a key role in lots of cancers. The outcomes of upregulated circular RNA forkhead box K2 (circFOXK2) on non-small cell lung cancer (NSCLC) persisted uncertainly. In this study, the role of circFOXK2 in NSCLC was inspected.

METHODS

The abundances of circFOXK2, microRNA-485-5p (miR-485-5p) and programmed cell death ligand-1 (PD-L1) were confirmed by quantitative real-time PCR and western blot. Cell counting kit-8 (CCK-8) assay and clonogenic assay were accomplished to conclude the proliferation of NSCLC cells. Wound healing and transwell assays were implemented to evaluate cell migration and invasion. Lactate dehydrogenase (LDH) cytotoxicity assay was enforced to quantify the cytotoxicity of CD8+ T cells. Flow cytometry assay was employed to detect apoptosis. Besides, the mice experiments were utilized for in vivo tumorigenesis analysis. Dual-luciferase reporter assay was carried out to reveal the associations between miR-485-5p and circFOXK2 or PD-L1.

RESULTS

CircFOXK2 and PD-L1 levels were augmented in NSCLC. CircFOXK2 targeted miR-485-5p, which could bind to PD-L1. CircFOXK2 served a key role in NSCLC tumorigenesis and cytotoxicity of CD8+ T cells. MiR-485-5p inhibition or PD-L1 overexpression abolished the inhibitory effects of circFOXK2 lack on NSCLC tumorigenesis and cytotoxicity of CD8+ T cells.

CONCLUSION

CircFOXK2 sponged miR-485-5p to stimulate PD-L1 and expedited NSCLC development.

Exosomes in triple negative breast cancer: From bench to bedside

Exosomes are lipid bilayer extracellular vesicles with a size of 30-150 nm, which can be released by various types of cells including breast cancer cells. Exosomes are enriched with multiple nucleic acids, lipids, proteins and play critical biological roles by binding to recipient cells and transmitting various biological cargos. Studies have reported that tumor-derived exosomes are involved in cancer initiation and progression, such as promoting cancer invasion and metastasis, accelerating angiogenesis, contributing to epithelial-mesenchymal transition, and enhancing drug resistance in tumors. Recently the dysregulating of exosomes has been found in triple-negative breast cancer (TNBC), relating to the clinicopathological characteristics and prognosis of TNBC patients. Considering the poor prognosis and lack of adequate response to conventional therapy of TNBC, the discovery of certain exosomes as a new target for diagnosis and treatment of TNBC may be a good choice that provides new opportunities for the early diagnosis, clinical treatment of TNBC. Here, we first discuss the innovative prognostic and predictive effects of exosomes on TNBC, as well as the practical clinical problems. Secondly, we focus on the new therapeutic areas represented by exosomes, especially the impact of introducing exosomes in TNBC treatment in the future.