Circular RNAs in cancer: new insights into functions and implications in ovarian cancer

Circular RNA circitga7 accelerates glioma progression via miR-34a-5p/VEGFA axis

Circular RNAs (circRNAs) are a group of noncoding RNAs derived from back-splicing events. CircRNA is reported to be involved in various tumor progressions, including glioma. Although there are a few reports of circular RNAs participating in gliomas, it is still unclear whether circular RNAs regulate the occurrence of gliomas. In our research, we found that the expression of circITGA7 in glioma tissues and glioma cells increased significantly. Knocking down circITGA7 can significantly inhibit the proliferation of glioma cells and reduce cell metastasis. Through analysis and dual-luciferase report assay, we found that circITGA7 acts as a sponge for miR-34a-5p targeting VEGFA in glioma. Our study showed that circITGA7 regulates the proliferation and metastasis of glioma cell lines (SW1783&U373) by regulating the miR-34a-5p/VEGFA pathway. In conclusion, our study revealed a regulatory loop for the circITGA7/miR-34a-5p/VEGFA axis to regulate glioma development.

Cervical Cancer Diagnosis: Insights into Biochemical Biomarkers and Imaging Techniques

Cervical malignancy is known as one of the important cancers which is originated from cervix. This malignancy has been observed in women infected with papillomavirus who had regular oral contraceptives, multiple pregnancies, and sexual relations. Early and fast cervical cancer diagnosis is known as two important aspects of cervical cancer therapy. Several investigations indicated that early and fast detection of cervical cancer could be associated with better treatment process and increasing survival rate of patients with this malignancy. Imaging techniques are very important diagnosis tools that could be employed for diagnosis and following responses to therapy in various cervical cancer stages. Multiple lines of evidence indicated that utilization of imaging techniques is related to some limitations (i.e. high cost, and invasive effects). Hence, it seems that along with using imaging techniques, finding and developing new biomarkers could be useful in the diagnosis and treatment of subjects with cervical cancer. Taken together, many studies showed that a variety of biomarkers including, several proteins, mRNAs, microRNAs, exosomes and polymorphisms might be introduced as prognostic, diagnostic and therapeutic biomarkers in cervical cancer therapy. In this review article, we highlighted imaging techniques as well as novel biomarkers for the diagnosis of cervical cancer.

TCEB3 is Regulated by Circ-0000212/miR-140-3p Axis to Promote the Progression of Cervical Cancer

BACKGROUND

Cervical cancer is a common female malignancy, which accounts for a large proportion of cancer-related mortality in the world. Therefore, exploring the mechanisms of cervical cancer progression and seeking new therapeutic targets are extraordinarily needful. The aim of this study was to explore the role of TCEB3 in cervical cancer progression.

METHODS

TCEB3 expression was detected in cervical cancer tissue and adjacent normal tissues using qRT-PCR and immunohistochemistry analysis. TCEB3 expression was measured in cells using Western blot and qRT-PCR assay. Flow cytometer, CCK-8, colony formation and transwell assays were used to detect cell apoptosis, viability, colony-forming ability and invasion of cervical cancer cells. The expression of Ki-67, MMP-2, and MMP-9 was detected using Western blot. Bioinformatics analysis was used to predict circRNA-miRNA and miRNA-mRNA interactions. RIP and luciferase reporter assay were used to determine the interaction relationship.

RESULTS

TCEB3 expression was up-regulated in both cervical cancer tissues and cells. Silencing of TCEB3 inhibited cell proliferation and invasion and promoted apoptosis of cervical cancer cells. Additionally, silencing of TCEB3 reduced the protein expression of Ki-67, MMP-2, and MMP-9 of cervical cancer cells. Mechanistically, we identified that TCEB3 was directly targeted gene of miR-140-3p, and circ-0000212 acted as a sponge of miR-140-3p. Moreover, TCEB3 was regulated by circ-0000212/miR-140-3p axis and played a tumor promotive role in cervical cancer.

CONCLUSION

Silencing of TCEB3 attenuated cell proliferation and invasion and promoted apoptosis of cervical cancer cells, and this effect was regulated by circ-0000212/miR-140-3p axis. Our findings may provide a novel promising target for cervical cancer treatment.

Circular RNAs and Hepatocellular Carcinoma: New Epigenetic Players With Diagnostic and Prognostic Roles

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Due to the lack of potent diagnosis and prognosis biomarkers and effective therapeutic targets, the overall prognosis of survival is poor in HCC patients. Circular RNAs (circRNAs) are a class of novel endogenous non-coding RNAs with covalently closed loop structures and implicated in diverse physiological processes and pathological diseases. Recent studies have demonstrated the involvement of circRNAs in HCC diagnosis, prognosis, development, and drug resistance, suggesting that circRNAs may be a class of novel targets for improving HCC diagnosis, prognosis, and treatments. In fact, some artificial circRNAs have been engineered and showed their therapeutic potential in treating HCV infection and gastric cancer. In this review, we introduce the potential of circRNAs as biomarkers for HCC diagnosis and prognosis, as therapeutic targets for HCC treatments and discuss the challenges in circRNA research and chances of circRNA application.

Research Progress of Circular RNA in Gastrointestinal Tumors

circular RNA (circRNA) is a closed ring structure formed by cyclic covalent bonds connecting the 5’-end and 3’-end of pre-mRNA. circRNA is widely distributed in eukaryotic cells. Recent studies have shown that circRNA is involved in the pathogenesis and development of multiple types of diseases, including tumors. circRNA is specifically expressed in tissues. And the stability of circRNA is higher than that of linear RNA, which can play biological roles through sponge adsorption of miRNA, interaction with RNA binding protein, regulation of gene transcription, the mRNA and protein translation brake, and translation of protein and peptides. These characteristics render circRNAs as biomarkers and therapeutic targets of tumors. Gastrointestinal tumors are common malignancies worldwide, which seriously threaten human health. In this review, we summarize the generation and biological characteristics of circRNA, molecular regulation mechanism and related effects of circRNA in gastrointestinal tumors.

Vitamin D and Non-coding RNAs: New Insights into the Regulation of Breast Cancer

Breast cancer, a life-threatening serious disease with a high incident rate among women, is responsible for thousands of cancer-associated death worldwide. Numerous investigations have evaluated the possible mechanisms related to this malignancy. Among them, non-coding RNAs (ncRNAs), i.e., microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs have recently attracted attention of researchers. In addition to recent studies for evaluating the role of ncRNAs in breast cancer etiology, some investigations have revealed that vitamin D has regulatory and therapeutic roles in breast cancer. Moreover, an important link between vitamin D and ncRNAs in cancer therapy has been highlighted. Herein, the aim of this study was to discuss the available data on the mentioned link in breast cancer.

Circular RNA hsa_circ_101555 promotes hepatocellular carcinoma cell proliferation and migration by sponging miR-145-5p and regulating CDCA3 expression

Circular RNAs have been reported to play significant roles in regulating pathophysiological processes while also guiding clinical diagnosis and treatment of hepatocellular carcinoma (HCC). However, only a few circRNAs have been identified thus far. Herein, we investigated the role of a specific closed-loop structure of hsa_circ_101555 that was generated by back-splicing of the host gene casein kinase 1 gamma 1 (CSNK1G1) in the development and proliferation of HCC. We investigated the expression of Hsa_circ_101555 in HCC and normal tissues using bioinformatics. The expression level of hsa_circ_101555 was further detected by fluorescence in situ hybridization and qRT-PCR in ten HCC patients. Transwell, migration, WST-1 assays, and colony formation assays were used to evaluate the role of hsa_circ_101555 in HCC development and proliferation. The regulatory mechanisms of hsa_circ_101555 in miR-145-5p and CDCA3 were determined by dual luciferase reporter assay. A mouse xenograft model was also used to determine the effect of hsa_circ_101555 on HCC growth in vivo. hsa_circ_101555 showed greater stability than the linear RNA; while in vitro and in vivo results demonstrated that hsa_circ_101555 silencing significantly suppressed cell proliferation, migration, and invasion of HCC cells. Rescue experiments further demonstrated that suppression of miR-145-5p significantly attenuated the biological effects of hsa_circ_101555 knockdown in HCC cells. We also identified a putative oncogene CDCA3 as a potential miR-145-5p target. Thus, our results demonstrated that hsa_circ_101555 might function as a competing endogenous RNA of miR-145-5p to upregulate CDCA3 expression in HCC. These findings suggest that hsa_circ_101555 may be a potential therapeutic target for patients with HCC.

circCCND1 Regulates Oxidative Stress and FGF9 to Enhance Chemoresistance of Non-Small Cell Lung Cancer via Sponging miR-187-3p

Circular RNAs have been shown to regulate cancer tumorigenesis and drug resistance. Recently, circCCND1 is reported to promote laryngeal squamous cell carcinoma; however, whether circCCND1 is implicated in non-small cell lung cancer (NSCLC) remains unclear. In this research, The Cancer Genome Atlas data of lung adenocarcinoma were analyzed to show gene expression and overall survival. 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide assay and cell colony formation assay were utilized to measure cell viability and proliferation of A549 and HCC827. Apoptosis was detected by TdT-mediated dUTP Nick-End Labeling assay. Besides, reverse transcription-quantitative PCR was used to examine gene expression. We observed that circCCND1 was significantly upregulated in lung cancer cells and patients. circCCND1 knockdown attenuated cell proliferation and induced apoptosis under cisplatin treatment. Mechanistically, circCCND1 interacted with miR-187-3p to regulate reactive oxygen species and FGF9 in NSCLC cells. Finally, miR-187-3p was demonstrated to rescue circCCND1 knockdown-modulated chemoresistance of NSCLC cells. In this study, our conclusions facilitate the understanding of NSCLC drug resistance to cisplatin.

Use of Salmonella Bacteria in Cancer Therapy: Direct, Drug Delivery and Combination Approaches

Over the years, conventional cancer treatments, such as chemotherapy with only a limited specificity for tumors, have undergone significant improvement. Moreover, newer therapies such as immunotherapy have undergone a revolution to stimulate the innate as well as adaptive immune responses against the tumor. However, it has been found that tumors can be selectively colonized by certain bacteria, where they can proliferate, and exert direct oncolytic effects as well as stimulating the immune system. Bacterial-mediated cancer therapy (BMCT) is now one example of a hot topic in the antitumor field. Salmonella typhimurium is a Gram-negative species that generally causes self-limiting gastroenteritis in humans. This species has been designed and engineered in order to be used in cancer-targeted therapeutics. S. typhimurium can be used in combination with other treatments such as chemotherapy or radiotherapy for synergistic modification of the tumor microenvironment. Considerable benefits have been shown by using engineered attenuated strains for the diagnosis and treatment of tumors. Some of these treatment approaches have received FDA approval for early-phase clinical trials. This review summarizes the use of Salmonella bacteria for cancer therapy, which could pave the way towards routine clinical application. The benefits of this therapy include an automatic self-targeting ability, and the possibility of genetic manipulation to produce newly engineered attenuated strains. Nevertheless, Salmonella-mediated anticancer therapy has not yet been clinically established, and requires more research before its use in cancer treatment.

CircRNA May Not Be "Circular"

Circular RNA (circRNA) is a novel regulatory non-coding RNA and participates in diverse physiological and pathological processes. However, the structures and molecular mechanisms of circRNAs remain unclear. In this study, taking advantage of openly databases and bioinformatics analysis, we observed lots of internal complementary base-pairing sequences (ICBPS) existed in plenty of circRNAs, especially in extremely long circRNAs (el-circRNAs, > 5,000 nt). The result indicated that circRNA may not be a simple circular structure. In addition, we put forward the hypothesis of “open-close effect” in the transition for specific circRNA from normal state to morbid state. Taken together, our results not only expand the knowledge of circRNAs, but also highlight the potential molecular mechanism of circRNAs.

Drug resistance and Cancer stem cells

Therapy resistance is a major problem when treating cancer patients as cancer cells develop mechanisms that counteract the effect of therapeutic compounds, leading to fit and more aggressive clones that contribute to poor prognosis. Therapy resistance can be both intrinsic and/or acquired. These are multifactorial events, and some are related to factors including adaptations in cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), deregulation of key signaling pathways, drug efflux through ABC transporters, acquired mutations, evading apoptosis, and activation of DNA damage response among others. Among these factors, CSCs represent the major source of therapy resistance. CSCs are a subset of tumor cells that are capable of self-renewal and multilineage progenitor expansion that are known to be intrinsically resistant to anticancer treatments. Multiple clones of CSCs pre-exist, and some can adopt and expand easily to changes in the tumor microenvironment (TME) and/or in response to radio- and chemotherapy. A combination of both intrinsic and extrinsic factors contributes to CSC-mediated therapy resistance. In this review, we will focus on CSCs and therapy resistance as well as suggest strategies to eliminate CSCs and, therefore, overcome resistance. Video abstract.

The Potential Regulatory Roles of Circular RNAs in Tumor Immunology and Immunotherapy

Circular RNAs (circRNAs) are covalently closed RNA molecules in eukaryotes with features of high stability, tissue-specific and cell-specific expression. According to their biogenesis, circRNAs are mainly classified into five types, i.e. exonic circRNAs (EciRNAs), exon-intron circRNAs (EIciRNAs), intronic RNAs (CiRNAs), fusion circRNAs (f-circRNAs), and read-through circRNAs (rt-circRNAs). CircRNAs have been emerging as important non-coding regulatory RNAs in a variety of human cancers. CircRNA4s were revealed to exert regulatory function through multiple mechanisms, such as sponges/decoys of miRNAs and proteins, enhancers of protein functions, protein scaffolds, protein recruitment, or protein translation templates. Furthermore, some circRNAs are intensively associated with immune cells in tumor immune microenvironment (TIME), e.g. circARSP91 and natural killer cells. Through regulating immune checkpoint genes, circRNAs are demonstrated to modulate the immune checkpoint blockade immunotherapy, e.g. circCPA4 could up-regulate PD-L1 expression. In summary, we reviewed the molecular features of circRNAs and mechanisms how they exert functions. We further summarized functional implications of circRNA regulations in tumor immunology and immunotherapy. Further understanding of the regulatory roles of circRNAs in tumor immunology and immunotherapy will benefit tumor treatment.

microRNA in inflammatory bowel disease at a glance

Inflammatory bowel disease (IBD) as a chronic inflammation in colon and small intestine has two subtypes: ulcerative colitis (UC) and Crohn's disease (CD). Genome studies have shown that UC and CD are related to microRNAs (miRNAs) expression in addition to environmental factors. This article reviews important researches that have recently been done on miRNAs roles in CD and UC disease. First, miRNA is introduced and its biogenesis and function are discussed. Afterward, roles of miRNAs in inflammatory processes involved in IBD are showed. Finally, this review proposes some circulating and tissue-specific miRNAs, which are useful for CD and UC fast diagnosis and grade prediction. As a conclusion, miRNAs are efficient diagnostic molecules especially in IBD subtypes discrimination and can be used by microarray and real time PCR methods for disease detection and classification.

The expanding role of CDR1-AS in the regulation and development of cancer and human diseases

CircRNAs are a superabundant and highly conserved group of noncoding RNAs (ncRNAs) that are characterized by their high stability and integrity compared with linear forms of ncRNAs. Recently, their critical role in gene expression regulation has been shown; thus, it is not far-fetched to believe that their abnormal expression can be a cause of different kinds of diseases such as cancer, neurodegenerative, and autoimmune diseases. They can have a function in variety of biological processes such as microRNA (miRNA) sponging, interacting with RNA-binding proteins, or even an ability to translate to proteins. A huge challenge in finding diagnostic biomarkers is finding noninvasive biomarkers that can be detected in human fluids, especially blood samples. CircRNAs are becoming candidate biomarkers for diagnosis and prognosis of these diseases through their ability to transverse from the blood-brain barrier and their broad presence in circulating exosomes. The circRNA for miRNA-7 (ciRS-7) is newly recognized, and acknowledged to being related to human pathology and cancer progression. In this review, we first briefly summarize the latest studies about their characteristics, biogenesis, and their mechanisms of action in the regulation and development of human diseases. Finally, we provide a list of diseases that are linked to one member of this novel class of ncRNAs called ciRS-7.

Identification of KEY lncRNAs and mRNAs Associated with Oral Squamous Cell Carcinoma Progression

Background:

Oral squamous cell carcinoma (OSCC) has been the sixth most common cancer worldwide. Emerging studies showed long non-coding RNAs to play a key role in human cancers. However, the molecular mechanisms underlying the initiation and progression of OSCC remained to be further explored.

Objective:

The present study aimed to identify differentially expressed lncRNAs and mRNAs in OSCC.

Methods:

GSE30784 was analyzed to identify differentially expressed lncRNAs and mRNAs in OSCC. Protein-protein interaction network and co-expression network analyses were performed to reveal the potential roles of OSCC related mRNAs and lncRNAs.

Results:

In the present study, we identified 21 up-regulated lncRNAs and 54 down-regulated lncRNAs in OSCC progression. Next, we constructed a lncRNA related co-expression network in OSCC, which included 692 mRNAs and 2193 edges. Bioinformatics analysis showed that lncRNAs were widely co-expressed with regulating type I interferon signaling pathway, extracellular matrix organization, collagen catabolic process, immune response, ECM-receptor interaction, Focal adhesion, and PI3K-Akt signaling pathway. A key network, including lncRNA C5orf66-AS1, C21orf15, LOC100506098, PCBP1-AS1, LOC284825, OR7E14P, HCG22, and FLG-AS1, was found to be involved in the regulation of immune response to tumor cell, Golgi calcium ion transport, negative regulation of vitamin D receptor signaling pathway, and glycerol- 3-phosphate catabolic process. Moreover, we found higher expressions of CYP4F29P, PCBP1- AS1, HCG22, and C5orf66-AS1, which were associated with shorter overall survival time in OSCC samples.

Conclusions:

Our analysis can provide novel insights to explore the potential mechanisms underlying OSCC progression.

Diagnostic and Prognostic Significance of Dysregulated Expression of Circular RNAs in Osteosarcoma

OBJECTIVE

This study aimed to perform an updated meta-analysis to explore the clinical, diagnostic, and prognostic values of circRNAs in osteosarcoma.

METHODS

: PubMed, Web of Science, EMBASE, Scopus, and Cochrane Library were systematically searched up to December 15, 2020. Eligible studies regarding the relationship between circRNAs levels and clinicopathological, diagnostic, and prognostic values in osteosarcoma were included for study.

RESULTS

31 studies involving 1979 osteosarcoma patients were enrolled, with 22 studies on clinicopathological parameters, eleven on diagnosis, and 23 on prognosis. For clinical parameters, overexpression of oncogenic circRNAs was intimately correlated with larger tumor size, advanced Enneking stage, poor differentiation, and distant metastasis (DM). In contrast, the downregulated circRNAs showed negative correlation with Enneking stage and DM. For the diagnostic values, the summary area under the curve of circRNA for the discriminative efficacy between osteosarcoma patients and non-cancer counterparts was estimated to be 0.87, with a weighted sensitivity of 0.79, specificity of 0.81, respectively. For the prognostic significance, oncogenic circRNAs had poor overall survival (OS) and disease-free survival, while elevated expression of tumor-suppressor circRNAs were closely related to longer OS.

CONCLUSION

This study showed that aberrantly expressed circRNA signatures could serve as potential biomarkers in diagnosis and prognosis in osteosarcoma.

Review on circular RNAs and new insights into their roles in cancer

Circular RNAs (circRNAs) are a very interesting class of conserved single-stranded RNA molecules derived from exonic or intronic sequences by precursor mRNA back-splicing. Unlike canonical linear RNAs, circRNAs form covalently closed, continuous stable loops without a 5'end cap and 3'end poly(A) tail, and therefore are resistant to exonuclease digestion. The majority of circRNAs are highly abundant, and conserved across different species with a tissue or developmental-stage-specific expression. circRNAs have been shown to play important roles as microRNA sponges, regulators of gene splicing and transcription, RNA-binding protein sponges and protein/peptide translators. Emerging evidence reveals that circRNAs function in various human diseases, particularly cancers, and may function as better predictive biomarkers and therapeutic targets for cancer treatment. In consideration of their potential clinical relevance, circRNAs have become a new research hotspot in the field of tumor pathology. In the present study, the current understanding of the biogenesis, characteristics, databases, research methods, biological functions subcellular distribution, epigenetic regulation, extracellular transport and degradation of circRNAs was discussed. In particular, the multiple databases and methods involved in circRNA research were first summarized, and the recent advances in determining the potential roles of circRNAs in tumor growth, migration and invasion, which render circRNAs better predictive biomarkers, were described. Furthermore, future perspectives for the clinical application of circRNAs in the management of patients with cancer were proposed, which could provide new insights into circRNAs in the future.

Circular PVT1 regulates cell proliferation and invasion via miR-149-5p/FOXM1 axis in ovarian cancer

Long non-coding RNA plasmacytoma variant translocation 1 (PVT1) is a dysregulated gene in malignancy and is associated with oncogenesis. In this study, we found PVT1 RNA was an ovarian specific expressing gene, and overexpressed in multiple cancer types, including ovarian cancer (OV). Higher expression levels of PVT1 are related to shorter survival time in OV patients, especially in patients with advanced stage and grade. Recent studies indicated circular PVT1 also had an important role in cancer progression, whose roles in OV remain unclear. Knockdown of circular PVT1 significantly suppressed OV cell proliferation, migration and invasion. Bioinformatics analysis demonstrated that circular PVT1 was involved in regulating angiogenesis, osteoblast differentiation, regulation of cell growth, type B pancreatic cell proliferation, negative regulation of apoptotic process, phospholipid homeostasis, regulation of neurogenesis, definitive hemopoiesis, cell migration, regulation of glucose metabolic process, central nervous system development and type 2 immune response. Our data showed miR-149-5p targeted FOXM1, which was regulated by circular PVT1. Forkhead Box M1 (FOXM1) expression in ovarian cancer exhibited high level when compared with normal tissues, and had relation with relatively poor survival. FOXM1 promoted cell viability and reduced FOXM1 could rescue circular influence of circular PVT1-caused carcinoma induction. In conclusion, circular PVT1 increased FOXM1 level via binding to miR-149-5p and thus affected ovarian cancer cell viability and migration.

Gynecologic cancers and non-coding RNAs: Epigenetic regulators with emerging roles

Gynecologic cancers involve the female genital organs, such as the vulva, vagina, cervix, endometrium, ovaries, and fallopian tubes. The occurrence and frequency of gynecologic cancer depends on personal lifestyle, history of exposure to viruses or carcinogens, genetics, body shape, and geographical habitat. For a long time, research into the molecular biology of cancer was broadly restricted to protein-coding genes. Recently it has been realized that non-coding RNAs (ncRNA), including long noncoding RNAs (LncRNAs), microRNAs, circular RNAs and piRNAs (PIWI-interacting RNAs), can all play a role in the regulation of cellular function within gynecological cancer. It is now known that ncRNAs are able to play dual roles, i.e. can exert both oncogenic or tumor suppressive functions in gynecological cancer. Moreover, several clinical trials are underway looking at the biomarker and therapeutic roles of ncRNAs. These efforts may provide a new horizon for the diagnosis and treatment of gynecological cancer. Herein, we summarize some of the ncRNAs that have been shown to be important in gynecological cancers.

Circ_0109046 promotes the malignancy of endometrial carcinoma cells through the microRNA-105/SOX9/Wnt/β-catenin axis

Emerging evidence suggests the important involvements of circular RNAs (circRNAs) in cancer progression. This study focuses on the function of Circ_0109046 on the malignancy of endometrial carcinoma (EC) cells and the molecules involved. First, high expression of Circ_0109046 was found in EC tissues compared to the adjacent tissues, and it predicted unfavorable prognosis in patients. Similarly, high expression of Circ_0109046 was confirmed in EC cells relative to that in normal endometrial epithelial cells. Silencing of Circ_0109046 in AN3-CA cells inhibited proliferation and aggressiveness but increased apoptosis of cells. Circ_0109046 was mainly sub-localized in cytoplasm, and it mediated SOX9 expression through sponging microRNA (miR)-105. The proliferation and aggressiveness of EC cells suppressed by Circ_0109046 downregulation was recovered upon SOX9 overexpression. SOX9 activated the Wnt/β-catenin pathway. Furthermore, downregulation of Circ_0109046 reduced the growth of xenograft tumors in nude mice. This study evidenced that Circ_0109046 upregulates SOX9 expression through sponging miR105, leading to activation of Wnt/β-catenin signaling and the malignant growth of EC. This study may offer novel understanding in EC treatment.

Circular RNAs in Cardiac Regeneration: Cardiac Cell Proliferation, Differentiation, Survival, and Reprogramming

Circular RNAs (circRNAs) are classified as long non-coding RNAs (lncRNAs) that are characterized by a covalent closed-loop structure. This closed-loop shape is the result of a backsplicing event in which the 3' and 5' splice sites are ligated. Through the lack of 3' poly(A) tails and 5' cap structures, circRNAs are more stable than linear RNAs because these adjustments make the circular loop less susceptible to exonucleases. The majority of identified circRNAs possess cell- and tissue-specific expression patterns. In addition, high-throughput RNA-sequencing combined with novel bioinformatics algorithms revealed that circRNA sequences are often conserved across different species suggesting a positive evolutionary pressure. Implicated as regulators of protein turnover, micro RNA (miRNA) sponges, or broad effectors in cell differentiation, proliferation, and senescence, research of circRNA has increased in recent years. Particularly in cardiovascular research, circRNA-related discoveries have opened the door for the development of potential diagnostic and therapeutic tools. Increasing evidence links deviating circRNA expression patterns to various cardiovascular diseases including ischemic heart failure. In this mini-review, we summarize the current state of knowledge on circRNAs in cardiac regeneration with a focus on cardiac cell proliferation, differentiation, cardiomyocyte survival, and cardiac reprogramming.

Circular RNAs: Emerging Role in Cancer Diagnostics and Therapeutics

Circular RNAs (circRNAs) are rapidly coming to the fore as major regulators of gene expression and cellular functions. They elicit their influence via a plethora of diverse molecular mechanisms. It is not surprising that aberrant circRNA expression is common in cancers and they have been implicated in multiple aspects of cancer pathophysiology such as apoptosis, invasion, migration, and proliferation. We summarize the emerging role of circRNAs as biomarkers and therapeutic targets in cancer.

The novel circ_0028171/miR-218-5p/IKBKB axis promotes osteosarcoma cancer progression

Background

Recently, it has been demonstrated that circular RNA (circRNA) contributes to the production and progression in human cancer. However, the specific function and underlying mechanism of circ_0028171 in osteosarcoma (OS) still remain largely unclear and require to be investigated.

Methods

In our study, we confirmed differentially expressed circRNAs by microarray analysis in normal bone cells vs. OS cell lines. The expression of circ-0028171 in OS was measured by qRT-PCR. Nuclear-cytoplasmic fractionation was employed to identify the localization of circ-0028171, and RNase R and actinomycin D treatment were used to prove its circular characteristic. In vitro experiments, such as CCK-8 method, cell count, cell colony formation, transwell migration and invasion assays, and in vivo tumor models were adopted to evaluate the effect of circ_0028171. Further, luciferase reporter, RIP and RNA pull-down assays were conducted to confirm the binding sites of circ_0028171 with miR-218-5p.

Results

We found that circ_0028171 displayed a remarkably higher expression in both OS tissues and cell lines. Circ_0028171 mainly located in the cytoplasm as a stable cyclic transcript. Knockdown of circ_0028171 suppressed OS tumor growth in vitro and in vivo, while up-regulated circ_0028171 remarkably enhanced cell proliferation, migration and invasion abilities in OS. Several mechanistic experiments revealed that circ_0028171 served as a sponge of miR-218-5p to increase IKBKB expression.

Conclusions

our research reveals that circ_0028171 might promote the malignant behavior of OS tissues through miR-218-5p/IKBKB axis, which could be a potential novel marker for early diagnosis of OS.

Targeting of KDM5A by miR-421 in Human Ovarian Cancer Suppresses the Progression of Ovarian Cancer Cells

PURPOSE

The retinoblastoma binding protein RBP2 (KDM5A) is a histone demethylase that promotes cell growth in many human cancers. A series of functional experiments were conducted to explore the role of miR-421/KDM5A in ovarian cancer cells and their underlying molecular mechanisms.

MATERIALS AND METHODS

Public microarray databases were analyzed to assess KDM5A and miR-421 expression in ovarian cancer. KDM5A was predicted to be a target of miR-421 using software analysis. The expression of the miR-421/KDM5A regulatory axis in ovarian cancer and the mechanisms of its effects on proliferation, migration, and invasion of ovarian cancer cell lines were investigated.

RESULTS

Compared with normal ovarian tissues, the expression of KDM5A mRNA and protein was elevated (P<0.05), and miR-421 expression was reduced in ovarian cancer tissue (P<0.05). miR-421 was found to bind specifically to the KDM5A gene. Silencing KDM5A or overexpressing miR-421 significantly inhibited proliferation, migration, and invasion of OVCAR-8 and SKOV-3 cells. Similarly, compared with nude mice injected with cells transfected with empty capsids, the in vivo proliferation rate of OVCAR-8 cells after miR-421 overexpression was reduced significantly.

CONCLUSION

The miR-421/KDM5A regulatory axis plays an important role in the development and progression of ovarian cancer cells.

Circular RNA CircHIPK3 Elevates CCND2 Expression and Promotes Cell Proliferation and Invasion Through miR-124 in Glioma

As a malignant tumor of the central nervous system, glioma exhibits high incidence and poor prognosis. Circular RNA HIPK3 (circHIPK3) is a circular RNA (circRNA) related to cancer progression. However, the role of circHIPK3 in gliomas remains unclear. The purpose of this study was to investigate the role of circHIPK3 in gliomas and its mechanism. The qRT-PCR method was used to determine the expression pattern of circHIPK3 in glioma cell lines. CCK-8 assay was used to detect cell proliferation. Cell migration and invasion were evaluated using the Transwell assay. Our results showed that circHIPK3 expression was significantly up-regulated in glioma tissues and cell lines. In vitro, the down-regulation of circHIPK3 significantly inhibited the proliferation, migration and invasion of glioma cells. Besides, we demonstrated that circHIPK3 acted as a sponge to absorb miR-124 and promoted CCND2 expression. In summary, our results indicated that circHIPK3 had carcinogenic effects by regulating the expression of CCND2 in glioma by sponging miR-124. These findings provided favorable evidence to reveal the role of circHIPK3 in the development of gliomas.

Circ_0079593 facilitates proliferation, metastasis, glucose metabolism and inhibits apoptosis in melanoma by regulating the miR-516b/GRM3 axis

Many studies confirm that circular RNA (circRNA) plays an important regulatory role in the malignant progression of cancer, including melanoma. However, the role of a novel circRNA, circ_0079593, in melanoma is unclear. The expression levels of circ_0079593 and miR-516b were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was measured by cell counting kit-8 (CCK-8) assay, and cell migration and invasion were evaluated using transwell assay. Meanwhile, western blot (WB) analysis was employed to determine the levels of proliferation and metastasis-related proteins, as well as metabotropic glutamate receptor 3 (GRM3) protein. Furthermore, cell apoptosis was tested by detecting the cell apoptosis rate and Caspase-3 activity. The glucose consumption and lactate production of cells were measured to evaluate cell glucose metabolism. Moreover, dual-luciferase reporter assay and biotin-labeled RNA pull-down assay were used to confirm the interaction between miR-516b and circ_0079593 or GRM3. In addition, mice xenograft models were constructed to explore the effect of circ_0079593 on melanoma tumor growth in vivo. Our results discovered that circ_0079593 was highly expressed in melanoma, and its silencing suppressed melanoma cell proliferation, migration, invasion, glucose metabolism and promoted apoptosis. Moreover, we found that circ_0079593 could serve as a sponge of miR-516b, and miR-516b could target GRM3 in melanoma. The rescue experiments revealed that both miR-516b inhibitor and GRM3 overexpression could reverse the inhibition effect of circ_0079593 knockdown on melanoma progression. Additionally, in vivo experiments also revealed that circ_0079593 interference suppressed melanoma tumor growth. Our study concluded that circ_0079593 accelerated melanoma progression via upregulating GRM3 by sponging miR-516b, which suggested that circ_0079593 had the potential to be a new therapeutic biomarker for melanoma.

Chemotherapy and chemo-resistance in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is closely associated with Epstein-Barr virus (EBV) and occurs frequently in the south of China and Southeast Asian countries. Concurrent chemo-radiotherapy is one of the main treatments for NPC. Although, the combined treatment of chemo-radiotherapy produces a satisfying survival rate, the chemo-resistance arises as a big obstacle in curing recurrent NPC patients. The acquirement of chemo-resistance is usually along with a poor prognosis. So far, the mechanism of chemo-resistance in NPC has not been fully elucidated and there have not been a comprehensive review on this issue. Thus, it is of great significance to summarize the mechanisms involved in NPC chemo-resistance. In this review, the importance and limitations of chemotherapy and the mechanisms of chemo-resistances in NPC were discussed.

FOXA1-induced circOSBPL10 potentiates cervical cancer cell proliferation and migration through miR-1179/UBE2Q1 axis

Background

Recently, extensive evidence has clarified the crucial role of circular RNAs (circRNAs) as a pro-tumor or anti-cancer participant in human malignancies. A new circRNA derived from oxysterol binding protein like 10 (OSBPL10) (circOSBPL10) has not been researched in cervical cancer (CC) yet.

Methods

The expression of molecules was analyzed by RT-qPCR or western blot. Several functional assays were applied to explore the biological influence of circOSBPL10 on CC. The interaction between RNAs was estimated via luciferase reporter, RNA immunoprecipitation and RNA pull-down assays.

Results

CircOSBPL10 characterized with cyclic structure was revealed to possess elevated expression in CC cells. CircOSBPL10 downregulation elicited suppressive impacts on CC cell proliferation and migration. Interestingly, circOSBPL10 regulated CC progression by interacting with microRNA-1179 (miR-1179). Moreover, ubiquitin conjugating enzyme E2 Q1 (UBE2Q1) targeted by miR-1179 was positively regulated by circOSBPL10 in CC. Furthermore, enhanced UBE2Q1 expression or suppressed miR-1179 level countervailed the repressive effect of circOSBPL10 depletion on the malignant phenotypes of CC cells. Moreover, forkhead box A1 (FOXA1) was confirmed to induce circOSBPL10 expression in CC cells.

Conclusions

FOXA1-induced circOSBPL10 facilitates CC progression through miR-1179/UBE2Q1 axis, highlighting a strong potential for circOSBPL10 to serve as a promising therapeutic target in CC.

CircUBAP2 promotes SEMA6D expression to enhance the cisplatin resistance in osteosarcoma through sponging miR-506-3p by activating Wnt/β-catenin signaling pathway

The occurrence of chemo-resistance is an essential reason for the high morbidity of osteosarcoma (OS) patients. Circular RNAs (circRNAs) have been involved in the regulation of chemo-resistance in cancers. Semaphorins 6D (SEMA6D) is abnormally expressed in many cancers. However, the roles of circUBAP2 and SEMA6D in the chemo-resistance of OS are still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of circUBAP2, SEMA6D and microRNA-506-3p (miR-506-3p). The cisplatin resistance and proliferation of cells were evaluated by 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay. Western blot analysis was performed to measure the protein levels of Wnt/β-catenin signaling pathway biomarkers and SEMA6D. Also, the apoptosis, migration and invasion of cells were assessed by Flow cytometry and Transwell assays, respectively. Besides, Dual-luciferase reporter assay was used to verify the interaction between miR-506-3p and circUBAP2 or SEMA6D. We found that the expression levels of circUBAP2 and SEMA6D were increased in cisplatin-resistant OS tissues and cells. Knockdown of circUBAP2 inhibited the cisplatin resistance, silenced Wnt/β-catenin signaling pathway, hindered cell proliferation, migration and invasion, and promoted apoptosis in cisplatin-resistant OS cells, all of which could be reversed by overexpression of SEMA6D. MiR-506-3p could be sponged by circUBAP2 and could target SEMA6D. The suppression of miR-506-3p overexpression on the progression of OS cisplatin resistance could be reversed by SEMA6D overexpression, while miR-506-3p inhibitor also could invert the inhibitory effect of circUBAP2 silencing on the progression of OS cisplatin resistance. In conclusion, CircUBAP2 and SEMA6D played active roles in the progression of OS cisplatin resistance through miR-506-3p, which might provide some new ideas for studying the countermeasures of OS resistance.

Circular RNA MTO1 Inhibits the Proliferation and Invasion of Ovarian Cancer Cells Through the miR-182-5p/KLF15 Axis

Circular RNAs (circRNAs) are a novel class of endogenous noncoding RNAs and have been shown to play important roles in a variety of physiological processes. Recently, dysregulation of circRNAs has been identified in many types of cancers. In this study, we analyzed the expression profile and biological functions of circMTO1 in ovarian cancer. We demonstrated that circMTO1 was downregulated in ovarian cancer tissues and cell lines. Upregulation of circMTO1 inhibited proliferation and invasion of ovarian cancer cells while downregulation of circMTO1 promoted these processes. Mechanistically, we showed that circMTO1 sponged miR-182-5p to support KLF15 expression, eventually leading to inhibition of ovarian cancer progression. In conclusion, our study suggested circMTO1 as a novel biomarker and therapeutic target for ovarian cancer treatment.

Cardiac complications in inherited mitochondrial diseases

Maternally mitochondrial dysfunction includes a heterogeneous group of genetic disorders which leads to the impairment of the final common pathway of energy metabolism. Coronary heart disease and coronary venous disease are two important clinical manifestations of mitochondrial dysfunction due to abnormality in the setting of underlying pathways. Mitochondrial dysfunction can lead to cardiomyopathy, which is involved in the onset of acute cardiac and pulmonary failure. Mitochondrial diseases present other cardiac manifestations such as left ventricular noncompaction and cardiac conduction disease. Different clinical findings from mitochondrial dysfunction originate from different mtDNA mutations, and this variety of clinical symptoms poses a diagnostic challenge for cardiologists. Heart transplantation may be a good treatment, but it is not always possible, and other complications of the disease, such as mitochondrial encephalopathy, lactic acidosis, and stroke-like syndrome, should be considered. To diagnose and treat most mitochondrial disorders, careful cardiac, neurological, and molecular studies are needed. In this study, we looked at molecular genetics of MIDs and cardiac manifestations in patients with mitochondrial dysfunction.

Circular RNAs serve as miRNA sponges in breast cancer

Circular RNAs are a large group of non-coding RNAs with a closed-loop structure. circRNAs play significant roles in many biological processes as miRNA sponges, regulators for gene transcription, combining with RNA-binding proteins and translation of protein. Nowadays, circRNAs have become a research hotspot in the field of cancer and molecular biology. Accumulating evidences have indicated that circRNAs participate in the initiation and development of various cancers such as breast cancer. Breast cancer is a heterogeneous disease, which is the most common malignancy in women. The incidence and mortality rates of breast cancer indicate that it is the leading cause of cancer-related deaths. The goal of the present review is to introduce biogenesis, function characteristics and types of circRNAs, and also their biological functions on breast cancer, especially as miRNA sponges. Additionally, we discuss their use as a new therapeutic target for the treatment of breast cancer.

Circular RNA circHIPK3 Promotes Cell Metastasis through miR-637/STAT3 Axis in Osteosarcoma

Recent studies have suggested that circular RNAs play an important role in the progression of various cancers. However, few studies have revealed the great value of circRNAs in the diagnosis and prognosis prediction of osteosarcoma (OS). In this study, we performed experiments with the human OS cell lines and the results showed that the expression of circHIPK3 in OS cell lines was significantly upregulated compared to that in the normal cell line. In addition, the results showed that circHIPK3 could promote the migration, invasion, and growth of OS cells. Furthermore, miR-637 was identified as a target of circHIPK3, while STAT3 was targeted by miR-637. circHIPK3 could promote STAT3 expression via interacting with miR-637 in OS cells. In conclusion, our research uncovered an important role of the circHIPK3/miR-637/STAT3 pathway in the migration and invasion of OS cells and suggested that circHIPK3 may be a prognostic marker and a promising therapeutic target for OS.

Downregulation of circular RNA hsa_circ_0000735 boosts prostate cancer sensitivity to docetaxel via sponging miR-7

Background

One of the main reasons for the failure of prostate cancer (PCa) treatment is the generation of chemoresistance. Circular RNA hsa_circ_0000735 (hsa_circ_0000735) is connected with the progression of cancer. Nevertheless, the role and regulatory mechanism of hsa_circ_0000735 in the resistance of PCa to docetaxel (DTX) are unclear.

Methods

Expression levels of hsa_circ_0000735 and miR-7-5p (miR-7) in tissue samples and cells were examined via quantitative real-time polymerase chain reaction (qRT-PCR). The DTX sensitivity, viability, colony formation, cell cycle progression, and apoptosis of DTX-resistant PCa cells were determined via Cell Counting Kit-8 (CCK-8), cell colony formation, or flow cytometry assays. The levels of multidrug resistance protein 1 (MDR1) protein, cyclinD1, and B cell lymphoma 2 (bcl-2) were detected by western blotting. The interaction between hsa_circ_0000735 and miR-7 was verified via dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays. The role of hsa_circ_0000735 in vivo was validated through tumor formation experiments.

Results

Hsa_circ_0000735 was upregulated and miR-7 was downregulated in DTX-resistant PCa tissues and cells. High hsa_circ_0000735 expression had a shorter overall survival. Both hsa_circ_0000735 knockdown and miR-7 mimic boosted DTX sensitivity, constrained viability, colony formation, cell cycle progression, and fostered apoptosis of DTX-resistant PCa cells. Also, hsa_circ_0000735 silencing elevated DTX sensitivity and repressed tumor growth in PCa in vivo. Mechanistically, hsa_circ_0000735 served as a sponge for miR-7. MiR-7 inhibition overturned hsa_circ_0000735 silencing-mediated impacts on DTX sensitivity and the malignant behaviors of DTX-resistant PCa cells.

Conclusion

Hsa_circ_0000735 downregulation boosted PCa sensitivity to DTX and reduced tumor growth via sponging miR-7, providing a promising prognostic biomarker and therapeutic target for PCa.

Circular RNA-9119 suppresses in ovarian cancer cell viability via targeting the microRNA-21-5p-PTEN-Akt pathway

We aimed to assess the regulatory role of circular RNA (circRNA)-9119 (circ9119) in ovarian cancer (OC) cell viability. The expression of circ9119 was clearly reduced in OC tissues and cell lines, whereas the microRNA-21-5p (miR-21) levels were elevated compared with those in normal healthy control tissues and immortalized fallopian epithelial cell line FTE187. Further, circ9119 was overexpressed, causing a notable decrease in the viability and proliferation of OC cells and an increase in apoptosis. Further study showed that circ9119 upregulation resulted in a decrease in miR-21 levels. Bioinformatics forecasting (starBase and TargetScan) and dual luciferase reporter assay demonstrated that circ9119 acts as an miR-21 sponge. Recovery of miR-21 expression in circ9119-overexpressing OC cells showed that miR-21 exhibited the opposite effect on circ9119; moreover, its recovery could suppress the effects of circ9119 overexpression, recover cell proliferation, and reduce apoptosis. Furthermore, miR-21 was found to target phosphatase and tensin homologue (PTEN) 3′ untranslated region. PTEN protein and mRNA expression was reduced in OC tissues and cells, whereas it was increased on transfection with an miR-21 inhibitor. Thus, circ9119 could regulate cell proliferation and apoptosis of OC cells via by acting as an miR-21 sponge and targeting the PTEN–Akt pathway.

Circ_001569 regulates FLOT2 expression to promote the proliferation, migration, invasion and EMT of osteosarcoma cells through sponging miR-185-5p

Osteosarcoma (OS) is a common malignant tumor in the world. Circular RNAs are endogenous non-coding RNAs that have been linked to the development of cancer. However, the role of circ_001569 in OS progression is still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of circ_001569, microRNA-185-5p (miR-185-5p) and flotillin-2 (FLOT2). The abilities of cell proliferation, migration and invasion were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and Transwell assays, respectively. Also, western blot analysis was performed to assess the levels of epithelial-mesenchymal transition (EMT)-related proteins and FLOT2 protein. Besides, the dual-luciferase reporter assay was used to verify the interactions among circ_001569, miR-185-5p and FLOT2. Circ_001569 expression was increased in OS tissues and cells, and its knockdown reduced the proliferation, migration, invasion and EMT of OS cells. MiR-185-5p could interact with circ_001569. Inhibition of miR-185-5p could recover the suppression effects of silenced-circ_001569 on the proliferation and metastasis of OS cells. Furthermore, FLOT2 was a target of miR-185-5p. Overexpressed FLOT2 could restore the inhibition effects of miR-185-5p mimic on the proliferation and metastasis of OS cells. Also, FLOT2 expression was regulated by circ_001569 and miR-185-5p. In addition, circ_001569 knockdown also reduced the OS tumor growth in vivo. Circ_001569 might act as an oncogene in OS progression by regulating the miR-185-5p/FLOT2 axis, which provided a reliable new approach for the treatment of OS patients.

Dysregulated circRNA_100876 contributes to proliferation and metastasis of colorectal cancer by targeting microRNA-516b (miR-516b)

Colorectal cancer (CRC) is globally one of the most common malignant tumors. Increasing number of studies indicate that circular RNAs (circRNAs) play a significant role in the initiation and progression of CRC. However, the role of circRNA_100876 in CRC progression remains unclear. In this study, we investigated the expression and function of circRNA_100876 in CRC progression. The expression of circRNA_100876 and microRNA-516b (miR-516b) was compared in normal and CRC tissues using quantitative real-time polymerase chain reaction (RT-qPCR). In addition, proliferation, metastasis, and apoptosis of the cells were analyzed using Cell Counting Kit-8 (CCK-8) assay, Transwell assay, and flow cytometry, respectively. The relationship between circRNA_100876 and miR-516b was further verified using dual-luciferase reporter assay. Our data showed that circRNA_100876 was highly expressed in CRC tumor tissues, and the high expression gtransition (EMT)-related proteins. Furthermore, we found that the addition of miR-516b reversed the anti-tumor effect induced by the downregulation of circRNA_100876. In conclusion, this study revealed that circRNA_100876 is overexpressed in CRC tissues and represents a promising therapeutic target for CRC.

Overview of biological effects of Quercetin on ovary

Over the last few decades, using natural products has been increased to treat different diseases. Today, great attention has been pointed toward the usage of natural products such as flavonoids, especially Quercetin (QUR), in the treatment of diseases. QUR as a natural antioxidant has been traditionally used to prevent or treat a variety of diseases such as cancer, cardiovascular disease, polycystic ovary syndrome (PCOS), obesity, chronic inflammation, and reproductive system dysfunction. Several studies demonstrated that QUR acts as an anti-inflammatory, anti-apoptotic, antioxidant, and anticancer agent. With this in view, in this study, we intended to describe an overview of the biological effects of QUR on the ovary. QUR improves the quality of oocytes and embryos. It affects the proliferation and apoptosis and decreases the oxidative stress in granulosa cells (GCs). Furthermore, QUR can be used as a complementary and alternative therapy in ovarian cancer and it has beneficial effects in the treatment of PCOS patients. It seems that QUR as a supplementary factor has different activities for the treatment of different disorders and it also has bidirectional activities. However, further investigations are needed for understanding the efficacy of QUR in the treatment and improvement of gynecological patients.

Versatile role of curcumin and its derivatives in lung cancer therapy

Lung cancer is a main cause of death all over the world with a high incidence rate. Metastasis into neighboring and distant tissues as well as resistance of cancer cells to chemotherapy demand novel strategies in lung cancer therapy. Curcumin is a naturally occurring nutraceutical compound derived from Curcuma longa (turmeric) that has great pharmacological effects, such as anti-inflammatory, neuroprotective, and antidiabetic. The excellent antitumor activity of curcumin has led to its extensive application in the treatment of various cancers. In the present review, we describe the antitumor activity of curcumin against lung cancer. Curcumin affects different molecular pathways such as vascular endothelial growth factors, nuclear factor-κB (NF-κB), mammalian target of rapamycin, PI3/Akt, microRNAs, and long noncoding RNAs in treatment of lung cancer. Curcumin also can induce autophagy, apoptosis, and cell cycle arrest to reduce the viability and proliferation of lung cancer cells. Notably, curcumin supplementation sensitizes cancer cells to chemotherapy and enhances chemotherapy-mediated apoptosis. Curcumin can elevate the efficacy of radiotherapy in lung cancer therapy by targeting various signaling pathways, such as epidermal growth factor receptor and NF-κB. Curcumin-loaded nanocarriers enhance the bioavailability, cellular uptake, and antitumor activity of curcumin. The aforementioned effects are comprehensively discussed in the current review to further direct studies for applying curcumin in lung cancer therapy.

Pregnancy-associated changes in cervical noncoding RNA

Aim: To identify pregnancy-associated changes in cervical noncoding RNA (ncRNA), including miRNA and long noncoding RNA (lncRNA), and their potential effects on biologic processes. Materials & methods: We enrolled 21 pregnant women with term deliveries (≥37 weeks' gestation) in a prospective cohort and collected cervical swabs before 28 weeks' gestation. We enrolled 21 nonpregnant controls. We analyzed miRNA, lncRNA and mRNA expression, applying a Bonferroni correction. Results: Five miRNA and three lncRNA were significantly differentially (>twofold change) expressed. Putative miRNA targets are enriched in genes mediating organogenesis, glucocorticoid signaling, cell adhesion and ncRNA machinery. Conclusion: Differential cervical ncRNA expression occurs in the setting of pregnancy. Gene ontology classification reveals biological pathways through which miRNA may play a biologic role in normal pregnancy physiology.

CircUBAP2 promotes SEMA6D expression to enhance the cisplatin resistance in osteosarcoma through sponging miR-506-3p by activating Wnt/β-catenin signaling pathway

The occurrence of chemo-resistance is an essential reason for the high morbidity of osteosarcoma (OS) patients. Circular RNAs (circRNAs) have been involved in the regulation of chemo-resistance in cancers. Semaphorins 6D (SEMA6D) is abnormally expressed in many cancers. However, the roles of circUBAP2 and SEMA6D in the chemo-resistance of OS are still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of circUBAP2, SEMA6D and microRNA-506-3p (miR-506-3p). The cisplatin resistance and proliferation of cells were evaluated by 3-(4, 5-dimethyl-2 thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay. Western blot analysis was performed to measure the protein levels of Wnt/β-catenin signaling pathway biomarkers and SEMA6D. Also, the apoptosis, migration and invasion of cells were assessed by Flow cytometry and Transwell assays, respectively. Besides, Dual-luciferase reporter assay was used to verify the interaction between miR-506-3p and circUBAP2 or SEMA6D. We found that the expression levels of circUBAP2 and SEMA6D were increased in cisplatin-resistant OS tissues and cells. Knockdown of circUBAP2 inhibited the cisplatin resistance, silenced Wnt/β-catenin signaling pathway, hindered cell proliferation, migration and invasion, and promoted apoptosis in cisplatin-resistant OS cells, all of which could be reversed by overexpression of SEMA6D. MiR-506-3p could be sponged by circUBAP2 and could target SEMA6D. The suppression of miR-506-3p overexpression on the progression of OS cisplatin resistance could be reversed by SEMA6D overexpression, while miR-506-3p inhibitor also could invert the inhibitory effect of circUBAP2 silencing on the progression of OS cisplatin resistance. In conclusion, CircUBAP2 and SEMA6D played active roles in the progression of OS cisplatin resistance through miR-506-3p, which might provide some new ideas for studying the countermeasures of OS resistance.

Identification of Potential Diagnostic and Prognostic Pseudogenes in Hepatocellular Carcinoma Based on Pseudogene-miRNA-mRNA Competitive Network

Background

It is widely known that hepatocellular carcinoma (HCC) has high rates of morbidity and mortality. A large number of studies have indicated that pseudogenes have an important effect on the carcinogenesis of HCC. Pseudogenes can play a role through the ceRNA network. There have been numerous studies on lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA networks. However, the pseudogene-miRNA-mRNA network in HCC has rarely been researched or reported on.

Material/Methods

The Cancer Genome Atlas (TCGA) database was researched and differences between selected genes were studied. A pseudogene-miRNA-mRNA network was then constructed and clustering of pseudogenes was studied. The diagnostic value of the selected pseudogenes, their functions, and pathways were investigated using available databases to understand their possible pathogenic mechanism in HCC. The protein-protein interaction network of target genes was found and the top 10 hub genes were identified. Expression of hub genes in HCC tissues was then detected by RT-qPCR.

Results

By analyzing the gene difference and clinical data of HCC, we constructed a ceRNA network composed of 4 pseudogenes, 8 miRNAs, and 30 mRNAs. The pseudogenes AP000769.1, KRT16P1, KRT16P3, and RPLP0P2 were all correlated with the diagnosis and prognosis of HCC. Functional analyses through the Kyoto Encyclopedia of Genes and Genomes and the Gene Ontology databases indicated that pseudogenes can affect the physiological process of HCC through the p53 pathway. The top 10 hub genes identified were all highly expressed in HCC tissues and affected the patient survival rate.

Conclusions

In this study, 4 pseudogenes related to the diagnosis and prognosis of liver cancer were found through the construction of a ceRNA network. These 4 pseudogenes might constitute new therapeutic targets for liver cancer patients.

The circular RNA circMAST1 promotes hepatocellular carcinoma cell proliferation and migration by sponging miR-1299 and regulating CTNND1 expression

Circular RNAs (circRNAs) are a class of non-coding RNAs with a loop structure; however, their functions remain largely unknown. Growing evidence suggests that circRNAs play a pivotal role in the progression of malignant diseases. However, the expression profiles and function of circRNAs in hepatocellular carcinoma (HCC) remain unclear. We investigated the expression of microtubule-associated serine/threonine kinase 1 (MAST1) circRNA (circMAST1) in HCC and healthy tissues using bioinformatics, quantitative real-time PCR (qRT-PCR), and fluorescence in situ hybridization. Luciferase reporter assays were performed to assess the interaction between circMAST1 and miR-1299. Proliferation assays, colony formation assays, flow cytometry, transwell assays, and western blotting were also performed. A mouse xenograft model was also used to determine the effect of circMAST1 on HCC growth in vivo. CircMAST1 was upregulated in HCC tissues and cell lines; silencing via small interfering RNA inhibited migration, invasion, and proliferation of HCC cell lines in vitro as well as tumor growth in vivo. Furthermore, the expression of circMAST1 was positively correlated with catenin delta-1 (CTNND1) and negatively correlated with microRNA (miR)-1299 in HCC clinical samples. Importantly, circMAST1 sponged miR-1299 to stabilize the expression of CTNND1 and promoted tumorigenic features in HCC cell lines. We found that circMAST1 may serve as a novel biomarker for HCC. Moreover, circMAST1 elicits HCC progression by sponging miRNA-1299 and stabilizing CTNND1. Our data provide potential options for therapeutic targets in patients with HCC.

microRNAs as biomarkers of ovarian cancer

Introduction: Ovarian carcinoma (OC) is the leading cause of death in women with gynecologic cancers. Most patients are diagnosed at an advanced stage with a low five-year survival rate of 20-30%. Discovering novel biomarkers for early detection and outcome prediction of OC is an urgent medical need. miRNAs, a group of small non-coding RNAs, play critical roles in multiple biologic processes and cancer pathogenesis.Areas covered: We provide an in-depth look at the functions of miRNAs in OC, particularly focusing on their roles in chemoresistance and metastasis in OC. We also discuss the biological and clinical significance of miRNAs in exosomes and expand on long non-coding RNA which acts as ceRNA of miRNAs.Expert opinion: miRNAs participate in many biological processes including proliferation, apoptosis, chemoresistance, metastasis, epithelial-mesenchymal transition, and cancer stem cell. They will substantially contribute to our understanding of OC pathogenesis. Given their resistance to the degradation of ribonucleases and availability in plasma exosomes, miRNAs may serve as emerging biomarkers for cancer detection, therapeutic assessment, and prognostic prediction. Being a messenger, exosomal miRNAs are crucial for the crosstalk between cancer cells and stromal cells in tumor microenvironment.

Therapeutic potentials of curcumin in the treatment of non-small-cell lung carcinoma

Non-small-cell lung carcinoma (NSCLC) is one of the most lethal malignancies that include more than 80% of lung cancer cases worldwide. During the past decades, plants and plant-derived products have attracted great interest in the treatment of various human diseases. Curcumin, the turmeric isolated natural phenolic compound, has shown a promising chemo-preventive and anticancer agent. Numerous studies have shown that curcumin delays the initiation and progression of NSCLC by affecting a wide range of molecular targets and cell signalling pathways including NF-kB, Akt, MAPKS, BCL-2, ROS and microRNAs (miRNAs). However, the poor oral bioavailability and low chemical stability of curcumin remain as major challenges in the utilisation of this compound as a therapeutic agent. Different analogs of curcumin and new delivery systems (e.g., micelles, nanoparticles and liposomes) provided promising solutions to overcome these obstacles and improve curcumin pharmacokinetic profile. The present review focuses on current reported studies about anti-NSCLC effects of curcumin. NSCLC involved miRNAs whose expression is regulated by curcumin has also been discussed. Furthermore, recent researches on the use of curcumin analogs and delivery systems to enhance the curcumin benefits in NSCLC are also described.