Circular RNA: a novel biomarker for progressive laryngeal cancer

Mechanisms of circRNA/lncRNA-miRNA interactions and applications in disease and drug research

In recent years, breakthroughs in bioinformatics have been made with the discovery of many functionally significant non-coding RNAs (ncRNAs). The discovery of these ncRNAs has further demonstrated the multi-level characteristics of intracellular gene expression regulation, which plays an important role in assisting diagnosis, guiding clinical drug use and determining prognosis in the treatment process of various diseases. microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) are the three major types of ncRNAs that interact with each other. Studies have shown that lncRNAs and circRNAs can sponge miRNAs, thereby influencing normal physiological processes and regulating mRNA expression and, thus, the physiological state of cells. This paper summarizes the mechanism of action and research progress of the three ncRNA and seven types of modalities. This summary is intended to provide new ideas for diagnosing and treating diseases and researching and developing new drugs.

Construction of a serum diagnostic signature based on m5C-related miRNAs for cancer detection

Currently, no clinically relevant non-invasive biomarkers are available for screening of multiple cancer types. In this study, we developed a serum diagnostic signature based on 5-methylcytosine (m5C)-related miRNAs (m5C-miRNAs) for multiple-cancer detection. Serum miRNA expression data and the corresponding clinical information of patients were collected from the Gene Expression Omnibus database. Serum samples were then randomly assigned to the training or validation cohort at a 1:1 ratio. Using the identified m5C-miRNAs, an m5C-miRNA signature for cancer detection was established using a support vector machine algorithm. The constructed m5C-miRNA signature displayed excellent accuracy, and its areas under the curve were 0.977, 0.934, and 0.965 in the training cohort, validation cohort, and combined training and validation cohort, respectively. Moreover, the diagnostic capability of the m5C-miRNA signature was unaffected by patient age or sex or the presence of noncancerous disease. The m5C-miRNA signature also displayed satisfactory performance for distinguishing tumor types. Importantly, in the detection of early-stage cancers, the diagnostic performance of the m5C-miRNA signature was obviously superior to that of conventional tumor biomarkers. In summary, this work revealed the value of serum m5C-miRNAs in cancer detection and provided a new strategy for developing non-invasive and cost effective tools for large-scale cancer screening.

The therapeutic effect of exosomes from mesenchymal stem cells on colorectal cancer: Toward cell-free therapy

Colorectal cancer (CRC) is known for its high mortality rate and affects more men than women. The treatment requires invasive surgical interventions, however, the progression of CRC metastasis is difficult to control in most cases. Mesenchymal stem cells (MSCs) with their outstanding characteristics have been widely used in the treatment of degenerative diseases as well as cancers. They affect the tumor microenvironment through either cell-cell interactions or communications with their secretome. While stem cells may represent a dual role in tumor proliferation and progression, exosomes have attracted much attention as a cell-free therapy in CRC treatment. Exosomes derived from native or genetically modified MSCs, as well as exosomal microRNAs (miRNAs), have been evaluated on CRC progression. Moreover, MSC-derived exosomes have been used as a carrier to deliver anticancer agents in colorectal cancer. In this review, we overview and discuss the current knowledge in both stem cell-based and cell-free exosome therapy of CRC.

Functional Tumor Targeting Nano-Systems for Reprogramming Circulating Tumor Cells with In Situ Evaluation on Therapeutic Efficiency at the Single-Cell Level

Tumor heterogeneity is primarily responsible for treatment resistance and cancer relapses. Being critically important to address this issue, the timely evaluation of the appropriateness of therapeutic actions at the single-cell level is still facing challenges. By using multi-functionalized nano-systems with the delivery vector composed of histone for plasmids loading, hyaluronic acid for tumor targeting, and a fusion peptide for C-X-C motif chemokine receptor 4 (CXCR4） targeting as well as nuclear localization, the reprogramming of circulating tumor cells (CTCs) with in situ detection on biomarkers at the single-cell level is realized. By efficient co-delivery of the genome editing plasmid for CXCR4 knockout and molecular beacons for detection of upregulated mRNA biomarkers into CTCs in unprocessed whole blood, the therapeutic outcomes of genome editing at the single-cell level can be in situ evaluated. The single-cell analysis shows that CXCR4 in CTCs of cancer patients is efficiently downregulated, resulting in upregulated anticancer biomarkers such as p53 and p21. The study provides a facile strategy for in-depth profiling of cancer cell responses to therapeutic actions at single-cell resolution to evaluate the outcomes of treatments timely and conveniently.

A Super-Enhancer Driven by FOSL1 Controls miR-21-5p Expression in Head and Neck Squamous Cell Carcinoma

MiR-21-5p is one of the most common oncogenic miRNAs that is upregulated in many solid cancers by inhibiting its target genes at the posttranscriptional level. However, the upstream regulatory mechanisms of miR-21-5p are still not well documented in cancers. Here, we identify a super-enhancer associated with the MIR21 gene (MIR21-SE) by analyzing the MIR21 genomic regulatory landscape in head and neck squamous cell carcinoma (HNSCC). We show that the MIR21-SE regulates miR-21-5p expression in different HNSCC cell lines and disruption of MIR21-SE inhibits miR-21-5p expression. We also identified that a key transcription factor, FOSL1 directly controls miR-21-5p expression by interacting with the MIR21-SE in HNSCC. Moreover, functional studies indicate that restoration of miR-21-5p partially abrogates FOSL1 depletion-mediated inhibition of cell proliferation and invasion. Clinical studies confirmed that miR-21-5p expression is positively correlated with FOSL1 expression. These findings suggest that FOSL1-SE drives miR-21-5p expression to promote malignant progression of HNSCC

CircHIPK3 Promotes the Tumorigenesis and Development of Gastric Cancer Through miR-637/AKT1 Pathway

Circular RNA is a kind of RNA with a covalently closed loop, which has a complex ability to modulate genes in the process of tumorigenesis and metastasis. Nevertheless, how circular RNA functions in gastric cancer (GC) remains unclear. The effect of circHIPK3 in vitro was studied here. Quantitative real-time PCR (qRT-PCR) was employed to found that circHIPK3 markedly increased in GC tissues and cell lines. And low expression of circHIPK3 suppressed the GC cells growing and metabolizing. Then the bioinformatics tool predicted the downstream target of circHIPK3, and it was proved by the dual-luciferase report experiment. According to the results of bioinformatics analysis and experimental data, it was clarified that circHIPK3 acted as a sponge of miR-637, releasing its direct target AKT1. The dual-luciferase assay revealed that mir-637 could bind circHIPK3 and AKT1. qRT-PCR data indicated that overexpression circHIPK3 led to the low level of miR-637 and overexpressed miR-637 would reduce AKT1 level. Finally, we demonstrated that the low expression of miR-637 or overexpression of AKT1 could attenuate the anti-proliferative effects of si-circHIPK3. These results suggest that the circHIPK3/miR-637/AKT1 regulatory pathway may be associated with the oncogene and growth of gastric cancer. In short, a new circular RNA circHIPK3 and its function are identified, and the regulatory pathway of circHIPK3/miR-637/AKT1 in the tumorigenesis and development of gastric cancer is discovered.

MicroRNA-421 improves ischemia/reperfusion injury via regulation toll-like receptor 4 pathway

Objectives

The objective was to investigate the effects of microRNA-421 against myocardial ischemia/reperfusion injury in C57BL/6 mice.

Methods

Male C57BL/6 mice (n = 27) were randomly divided into three groups: normal control (NC) group (sham-treated); I/R model group, which underwent the I_30min/R_24h model (ischemia for 30 minutes followed by reperfusion for 24 hours); and the miRNA group, which were injected with miR-421. Pathology was assessed by hematoxylin and eosin staining and myocardial infarct size was measured by triphenyltetrazolium chloride staining. The apoptosis rate was measured by TUNEL assay, and relative expression of toll-like receptor-4 (TLR4), Janus kinase 2 (JAK2), and signal transducer and activator of translation 3 (STAT3) was evaluated by immunohistochemistry. Interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, and high mobility group protein B1 (HMGB1) serum concentrations were measured by ELISA.

Results

Compared with the NC group, in the model group, the myocardial infarction was large; inflammatory cell infiltration was severe; apoptosis was enhanced; expression of TLR4, JAK2, and STAT3 was increased; and serum concentrations of IL-6, TNF-α, IL-10, and HMGB1 were significantly increased. In the miRNA group, the ischemia/reperfusion injury was significantly improved.

Conclusions

Overexpression of miRNA-421 could reduce ischemia/reperfusion inflammatory response, perhaps via inactivation of TLR4, JAK2, and STAT3.

Circular RNA PIP5K1A promotes colon cancer development through inhibiting miR-1273a

BACKGROUND

Circular RNAs (circRNAs) are considered to be highly stable due to the closed structure, which are predominately correlated with the development and progression of a wide variety of cancers. Colon cancer is one of the most common malignancies worldwide. A recent study demonstrated the upregulated expression of circPIP5K1A in non-small cell lung cancer. However, few studies have investigated the relationship between circ_0014130 level and colon cancer. Therefore, elucidating the underlying mechanisms of circPIP5K1A’s role may help with the identification of novel diagnostic and therapeutic targets for colon cancer.

AIM

To investigate the status of circPIP5K1A in colon cancers and its effects on the modulation of cancer development.

METHODS

The expression level of circPIP5K1A in tissue and serum samples from colon cancer patients, as well as human colonic cancer cell lines was detected by real-time quantitative reverse transcription-polymerase chain reaction. Following the transfection of specifically synthesized small interfering RNA (siRNA) into colon cell lines, we used Hoechst staining assay to measure the ratio of cell death in the absence of circPIP5K1A. Moreover, we also used the Transwell assay to assess the migratory function of colon cells overexpressing circPIP5K1A. Additionally, we employed a series of bioinformatics prediction programs to predict the potential of circPIP5K1A-targeted miRNAs and mRNAs. The miR-1273a vector was constructed, and then transfected with or without circPIP5K1A vector into colon cancer cells. Afterwards, the expression of activator protein 1 (AP-1), interferon regulating factor 4 (IRF-4), caudal type homeobox 2 (CDX-2), and zinc finger of the cerebellum 1 (Zic-1) was detected by western blotting.

RESULTS

CircPIP5K1A was significantly upregulated in colon cancer tissue relative to their adjacent normal tissues. Knockdown of circPIP5K1A in colon cancer cells impaired cell viability and suppressed cell invasion and migration, while enforced expression of circPIP5K1A exhibited the opposite effects on cell migration. Bioinformatics prediction program predicted that the association of circPIP5K1A with miR-1273a, as well as AP-1, IRF-4, CDX-2, and Zic-1. Subsequent studies showed that overexpression of circPIP5K1A augmented the expression of AP-1 but attenuated the expression of IRF-4, CDX-2, and Zic-1. Reciprocally, overexpression of miR-1273a abrogated the oncogenic function of circPIP5K1A in colon cancers.

CONCLUSION

Overall, our data demonstrate the oncogenic role of circPIP5K1A-miR-1273a axis in regulation of colon cancer development, which provides a novel insights into colon cancer pathogenesis.

MicroRNAs in cancer cell death pathways: Apoptosis and necroptosis

To protect tissues and the organism from disease, potentially harmful cells are removed through programmed cell death processes, including apoptosis and necroptosis. These types of cell death are critically controlled by microRNAs (miRNAs). MiRNAs are short RNA molecules that target and inhibit expression of many cellular regulators, including those controlling programmed cell death via the intrinsic (Bcl-2 and Mcl-1), extrinsic (TRAIL and Fas), p53-and endoplasmic reticulum (ER) stress-induced apoptotic pathways, as well as the necroptosis cell death pathway. In this review, we discuss the current knowledge of apoptosis and necroptosis pathways and how these are impaired in cancer cells. We focus on how miRNAs disrupt apoptosis and necroptosis, thereby critically contributing to malignancy. Understanding which and how miRNAs and their targets affect cell death pathways could open up novel therapeutic opportunities for cancer patients. Indeed, restoration of pro-apoptotic tumor suppressor miRNAs (apoptomiRs) or inhibition of oncogenic miRNAs (oncomiRs) represent strategies that are currently being trialed or are already applied as miRNA-based cancer therapies. Therefore, better understanding the cancer type-specific expression of apoptomiRs and oncomiRs and their underlying mechanisms in cell death pathways will not only advance our knowledge, but also continue to provide new opportunities to treat cancer.

MicroRNA-664 suppresses the growth of cervical cancer cells via targeting c-Kit

Background

Cervical cancer is the second most common malignant cancer in women worldwide. Evidence indicated that miR-664 was significantly downregulated in cervical cancer. However, the mechanisms by which miR-664 regulates the tumorigenesis of cervical cancer remain unclear. Thus, this study aimed to investigate the role of miR-664 in cervical cancer.

Methods

Quantitative reverse transcription polymerase chain reaction was used to detect the level of miR-664 in tumor tissues and cell line. The dual luciferase reporter system assay and Western blotting were used to explore the interaction of miR-664 and c-Kit in cervical cancer.

Results

The expression of miR-664 in patients with cervical cancer was dramatically decreased compared with that in adjacent tissues. MiR-664 mimics significantly inhibited proliferation in SiHa cells via inducing apoptosis. In addition, miR-664 mimics induced apoptosis in SiHa cells via increasing the expressions of Bax and active caspase 3 and decreasing the level of Bcl-2. Moreover, dual-luciferase assay showed that c-Kit was the directly binding target of miR-664 in SiHa cells; overexpression of miR-664 downregulated the expression of c-Kit. Meanwhile, upregulation of miR-664 significantly decreased the levels of c-Myc and Cyclin D in cells. Furthermore, miR-664 markedly inhibited tumor growth of cervical cancer in xenograft.

Conclusion

Our data indicated that miR-664 exerted antitumor effects on SiHa cells by directly targeting c-Kit in vitro and in vivo. Therefore, miR-664 might be a potential therapeutic target for the treatment of patients with cervical cancer.

Circulating serum oncologic miRNA in pediatric juvenile pilocytic astrocytoma patients predicts mural nodule volume

BACKGROUND

Juvenile pilocytic astrocytomas represent the largest group of pediatric brain tumors. The ideal management for these tumors is early, total surgical resection. To detect and track treatment response, a screening tool is needed to identify patients for surgical evaluation and assess the quality of treatment. The identification of aberrant miRNA profiles in the sera of juvenile pilocytic astrocytoma patients could provide such a screening tool.

METHODS

The authors reviewed the serum profiles of 84 oncologically relevant miRNAs in pediatric juvenile pilocytic astrocytoma patients via qPCR screening.

RESULTS

miR-21, miR-15b, miR-23a, and miR-146b were significantly elevated in the sera of JPA patients as compared to non-oncologic controls, oncologic controls, and post-JPA resection samples (p < 0.001, 0.022, 0.034, 0.044). miR-21 had the highest AUC on ROC analysis (AUC > 0.99, sensitivity 75%, specificity 100%). All four miRNAs also correlated well with tumor mural nodule size, though they only poorly correlated with total tumor size, including cystic components (Spearman's R²: miR-21 91.7 vs 6.9%, miR-15b 86.3 vs 23.1%, miR-23a 85.8 vs 23.0%, miR-146b 59.8 vs 11.9%).

CONCLUSION

In this small pilot study, pediatric juvenile pilocytic astrocytoma patients had significant elevations in serum miR-21, miR-15b, miR-23a, and miR-146b levels that do not appear to be driven by hydrocephalus or local distortion of the intracranial contents. These alterations correlate with solid tumor component volume and reverse with complete tumor resection, suggesting that this serum miRNA profile may delineate biomarkers for screening and tracking juvenile pilocytic astrocytoma patients. Additional studies, with a larger cohort, are needed to verify these results.

Levels of MicroRNA Heterogeneity in Cancer Biology

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression, involved in the silencing of messenger RNA (mRNA) translation. The importance of miRNA signatures in disease screening, prognosis, and progression of different tumor types and subtypes is increasing. miRNA expression levels change depending on numerous factors. In this review, we are describing the circumstances under which miRNA levels can change, these are named 'levels' of heterogeneity of miRNAs. miRNAs can have oncogenic, tumor suppressive, or both roles depending on tumor type and target mRNA whose translation they silence. The expression levels of a single miRNA may vary across different cancer types and subtypes, indicating that a miRNA signature may be tissue specific. miRNA levels of expression also vary during disease formation and propagation, indicating the presence of a time profile for their expression. The complexity of the miRNA-mRNA interference network mirrors different genetic and epigenetic changes that influence miRNA and mRNA availability to each other, and hence, their binding ability. The potential role of miRNAs as biomarkers is two-fold; first, for monitoring of the phases of cancer pathogenesis, and second, to characterize the particular type/subtype of cancer. It is important that a particular miRNA should be characterized by examining as many types and subtypes of cancers as are available, as well as being extracted from different types of samples, in order to obtain a complete picture of its behavior and importance in the disease pathology.

Smooth muscle cells differentiated from mesenchymal stem cells are regulated by microRNAs and suitable for vascular tissue grafts

Tissue-engineered vascular grafts with long-term patency are greatly needed in the clinical settings, and smooth muscle cells (SMCs) are a critical graft component. Human mesenchymal stem cells (MSCs) are used for generating SMCs, and understanding the underlying regulatory mechanisms of the MSC-to-SMC differentiation process could improve SMC generation in the clinic. Here, we found that in response to stimulation of transforming growth factor-β1 (TGFβ1), human umbilical cord-derived MSCs abundantly express the SMC markers α-smooth muscle actin (αSMA), smooth muscle protein 22 (SM22), calponin, and smooth muscle myosin heavy chain (SMMHC) at both gene and protein levels. Functionally, MSC-derived SMCs displayed contracting capacity in vitro and supported vascular structure formation in the Matrigel plug assay in vivo More importantly, SMCs differentiated from human MSCs could migrate into decellularized mouse aorta and give rise to the smooth muscle layer of vascular grafts, indicating the potential of utilizing human MSC-derived SMCs to generate vascular grafts. Of note, microRNA (miR) array analysis and TaqMan microRNA assays identified miR-503 and miR-222-5p as potential regulators of MSC differentiation into SMCs at early time points. Mechanistically, miR-503 promoted SMC differentiation by directly targeting SMAD7, a suppressor of SMAD-related, TGFβ1-mediated signaling pathways. Moreover, miR-503 expression was SMAD4-dependent. SMAD4 was enriched at the miR-503 promoter. Furthermore, miR-222-5p inhibited SMC differentiation by targeting and down-regulating ROCK2 and αSMA. In conclusion, MSC differentiation into SMCs is regulated by miR-503 and miR-222-5p and yields functional SMCs for use in vascular grafts.

Comparative miRNA Expression Profile Analysis of Squamous Cell Carcinoma and Peritumoral Mucosa from the Meso- and Hypopharynx

BACKGROUND/AIM

The role of microRNAs (miRNA) in carcinogenesis is related to their genome-regulatory function. The aim of the present study was to identify and compare miRNA expression signatures of meso- and hypopharynx squamous cell cancers in consideration of the cancer field hypothesis.

PATIENTS AND METHODS

Thirteen snap-frozen biopsy series of tumors and peritumoral tissues from the meso- and hypopharynx were analyzed regarding their miRNA expression with quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

Significant miRNA expression changes of miR-21, -27a, -34a, -143 and -146a were found in peritumoral tissues that were dependent from the tumor location and the distance from the primary tumor site.

CONCLUSION

miRNA expression analysis was found to be appropriate for molecular segregation of tumor location and peritumoral tissue segments, and appears to be a promising marker for cancer field characterization.

Analysis of gene expression profiling variations induced by hsa‑miR‑145‑5p‑overexpression in laryngeal squamous cell carcinoma cell line Tu‑177

The present study aimed to investigate the variations of the gene network and biological functions induced by hsa‑miR‑145‑5p in the laryngeal squamous cell carcinoma (LSCC) cell line Tu‑177. A hsa‑miR‑145‑5p‑overexpressed Tu‑177 cell model was established, and the gene expression microarray data of miR‑145‑5p‑overexpressed cells and negative control (NC) cells were analyzed. The differentially expressed genes (DEGs) between two groups were identified, and their potential functions were predicted by functional enrichment analysis. Furthermore, the targets of miR‑145‑5p were identified from the DEGs, and their potential functions and protein‑protein interactions (PPIs) were analyzed. The mRNA expressions of acetyl‑CoA carboxylase β (ACACB), fibroblast growth factor receptor 1 (FGFR1), protein phosphatase 3 catalytic subunit a (PPP3CA) and spleen associated tyrosine kinase (SYK), were analyzed via quantitative polymerase chain reaction. A total of 1,501 upregulated and 887 downregulated genes were identified in the hsa‑miR‑145‑5p‑overexpressed Tu‑177 cells, compared with the NC cells. Of these DEGs, 164 upregulated and 221 downregulated genes were predicted to be targeted by hsa‑miR‑145‑5p. The upregulated target genes were primarily associated with functions of immunity, whereas the downregulated target genes were significantly enriched in the p53 signaling pathway. In the PPI network consisting of 267 target genes, the upregulated ACACB had the greatest degree and interacted with downregulated genes including PPP3CA and SYK, in addition to upregulated genes, including FGFR1. The mRNA expressions of ACACB and FGFR1were markedly enhanced in miR‑145‑5p‑overexpressed Tu‑177 cells, whereas overexpressing miR‑145‑5p significantly reduced mRNA expression of PPP3CA and SYK. hsa‑miR‑145‑5p may exhibit an anticancer role in LSCC via regulating multiple cell processes, including cell proliferation and invasion, fatty acid metabolism, immunity and p53 signaling pathway. These findings provide novel information for the future investigation of miR‑145‑5p functions in LSCC.

Atherosclerosis and Cancer; A Resemblance with Far-reaching Implications

Atherosclerosis and cancer are chronic diseases considered two of the main causes of death all over the world. Taking into account that both diseases are multifactorial, they share not only several important molecular pathways but also many ethiological and mechanistical processes from the very early stages of development up to the advanced forms in both pathologies. Factors involved in their progression comprise genetic alterations, inflammatory processes, uncontrolled cell proliferation and oxidative stress, as the most important ones. The fact that external effectors such as an infective process or a chemical insult have been proposed to initiate the transformation of cells in the artery wall and the process of atherogenesis, emphasizes many similarities with the progression of the neoplastic process in cancer. Deregulation of cell proliferation and therefore cell cycle progression, changes in the synthesis of important transcription factors as well as adhesion molecules, an alteration in the control of angiogenesis and the molecular similarities that follow chronic inflammation, are just a few of the processes that become part of the phenomena that closely correlates atherosclerosis and cancer. The aim of the present study is therefore, to provide new evidence as well as to discuss new approaches that might promote the identification of closer molecular ties between these two pathologies that would permit the recognition of atherosclerosis as a pathological process with a very close resemblance to the way a neoplastic process develops, that might eventually lead to novel ways of treatment.

Downregulation of miRNA-26b inhibits cancer proliferation of laryngeal carcinoma through autophagy by targeting ULK2 and inactivation of the PTEN/AKT pathway

Laryngeal carcinoma is one of the most common tumors of the head and neck cancers, the pathogenesis of which remains yet unclear. It has been discovered through research that microRNAs (miRNAs) play an important role during the genesis of laryngeal carcinoma. In the present study we investigated the effect of miRNA-26b on the proliferation of laryngeal carcinoma and elucidated the potential underlying mechanisms in order to provide new targets for laryngeal carcinoma. Firstly, we found that miRNA-26b expression was significantly increased in patients with laryngeal carcinoma, compared with normal volunteers. The downregulation of miRNA-26b inhibited cell proliferation and induced apoptosis of Hep-2 cells. Furthermore, downregulation of the expression of miRNA‑26b promoted Bax, LC3 and p62 protein expression, decreased ULK2 mRNA and protein expression, as well as PTEN protein expression and increased phosphorylated‑AKT protein expression in Hep-2 cells as determined using quantification by real-time PCR and western blotting. The concomitant downregulation of ULK2 and miRNA-26b futher enhanced the miRNA‑26b-induced autophagy and apoptosis in addition to the miRNA-26b-inhibited cell proliferation of Hep-2 cells by targeting ULK2 and inactivating the PTEN/AKT pathway as determined by immunocytofluorescence. These findings revealed that miRNA-26b may play a key role in cell growth and death of laryngeal carcinoma through ULK2 and the PTEN/AKT pathway, and thus may be a new target for gene therapy in laryngeal carcinoma.