circ_0007385 served as competing endogenous RNA for miR-519d-3p to suppress malignant behaviors and cisplatin resistance of non-small cell lung cancer cells

Noncoding RNA (ncRNA)-mediated regulation of TLRs: critical regulator of inflammation in tumor microenvironment

Toll-like receptors (TLRs) are central components of the innate immune system as they recognize molecular patterns associated with pathogens and cellular damage and initiate immune responses using MyD88- and TRIF-dependent pathways. In contrast to being very useful for immune defense, dysregulated TLR signaling may be involved in diseases, such as cancer and autoimmune conditions. In cancer, TLRs create an environment that supports tumorigenesis and growth. In addition to this, a class of multifunctional noncoding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, regulate gene expression without encoding proteins. MiRNAs regulate gene expression in a fine-tuned manner, while lncRNAs and circRNAs do so via diverse mechanisms. Notably, these ncRNAs interact, where lncRNAs and circRNAs function as competing endogenous RNAs and ceRNA, affecting miRNA activity. This interaction has a vital role in cancer pathology, in influencing that of various oncogenes and tumor suppressors in the tumor microenvironment; hence, modulation of ncRNAs could also be a great promising therapeutic approach. In this context, interplay between TLRs and ncRNAs is of paramount importance as they influence various parameters of the tumor microenvironment. TLR signaling works upon the expression of ncRNAs, while ncRNAs work back to regulate TLR signaling in return. An example of this includes miRNA targeting of components of the TLR; lncRNAs induced by TLR signaling possibly would favor tumor progression. Pharmacological interventions directed toward inhibiting these TLR pathways could be the model to halt malignancy by hampering pro-tumor inflammation and boosting immune responses against neoplasms. Hence, the review will highlight the complicated contrast of ncRNAs and TLRs within human cancer. By connecting the mechanisms, the researchers may study more about tumorigenesis and gather up new, innovative notions regarding therapeutic targeting.

Circular RNAs as key regulators in cancer hallmarks: New progress and therapeutic opportunities

Circular RNAs (circRNAs) have emerged as critical regulators in cancer biology, contributing to various cancer hallmarks, including cell proliferation, apoptosis, metastasis, and drug resistance. Defined by their covalently closed loop structure, circRNAs possess unique characteristics like high stability, abundance, and tissue-specific expression. These non-coding RNAs function through mechanisms such as miRNA sponging, interactions with RNA-binding proteins (RBPs), and modulating transcription and splicing. Advances in RNA sequencing and bioinformatics tools have enabled the identification and functional annotation of circRNAs across different cancer types. Clinically, circRNAs demonstrate high specificity and sensitivity in samples, offering potential as diagnostic and prognostic biomarkers. Additionally, therapeutic strategies involving circRNA mimics, inhibitors, and delivery systems are under investigation. However, their precise mechanisms remain unclear, and more clinical evidence is needed regarding their roles in cancer hallmarks. Understanding circRNAs will pave the way for novel diagnostic and therapeutic approaches, potentially improving patient outcomes.

The modulation of immune cell death in connection to microRNAs and natural products

Immunogenic cell death (ICD) spatiotemporally regulates damage-associated molecular patterns (DAMPs) derived from dying cancer cells to signal the immune response. Intriguingly, these DAMPs and cytokines also induce cellular responses in non-immune cells, particularly cancer cells. Several ICD-modulating natural products and miRNAs have been reported to regulate the DAMP, cytokine, and cell death responses, but they lack systemic organization and connection. This review summarizes the impacts of natural products and miRNAs on the DAMP and cytokine responses and cancer cell death responses (apoptosis, autophagy, ferroptosis, necroptosis, and pyroptosis). We establish the rationale that ICD inducers of natural products have modulating effects on miRNAs, targeting DAMPs and cytokines for immune and cancer cell death responses. In conclusion, DAMP, cytokine, and cell death responses are intricately linked in cancer cells, and they are influenced by ICD-modulating natural products and miRNAs.

[Predictive Value of A miRNA Signature for Distant Metastasis in Lung Cancer]

BACKGROUND

Lung cancer represents the main cause of cancer-related deaths worldwide, and non-small cell lung cancer (NSCLC) is the most main subtype. More than half of NSCLC patients have already developed distant metastasis (DM) at the time of diagnosis and have a poor prognosis. Therefore, it is necessary to find new biomarkers for predicting NSCLC DM in order to guide subsequent treatment and thus improve the prognosis of NSCLC patients. Numerous studies have shown that microRNAs (miRNAs) are abnormally expressed in lung cancer tissues and play an important role in tumorigenesis and progression. The aim of this study is to identify differentially expressed miRNAs in lung adenocarcinoma tissues with DM group compared to those with non-distant metastasis (NDM) group, and to construct a miRNA signature for predicting DM of lung adenocarcinoma.

METHODS

We first obtained miRNA and clinical data for patients with lung adenocarcinoma from The Cancer Genome Atlas (TCGA) database. Subsequently, bioinformatics analysis, which included different R packages, Kaplan-Meier analysis, receiver operating characteristic (ROC) curve, and a range of online analysis tools, was performed to analyze the data.

RESULTS

A total of 12 differentially expressed miRNAs were identified between the DM and NDM groups, and 8 miRNAs (miR-377-5p, miR-381-5p, miR-490-5p, miR-519d-5p, miR-3136-5p, miR-320e, miR-2355-5p, miR-6784-5p) were screened for constructing a miRNA signature. The efficacy of this miRNA signature in predicting DM was good with an area under the curve (AUC) of 0.831. Logistic regression analysis showed that this miRNA signature was an independent risk factor for DM of lung adenocarcinoma. Next, target genes of the eight miRNAs were predicted, and enrichment analysis showed that these target genes were enriched in a variety of pathways, including pathways in cancer, herpes simplex virus I infection, PI3K-Akt pathway, MAPK pathway, Ras pathway, etc. CONCLUSIONS: This miRNA signature has good efficacy in predicting DM of lung adenocarcinoma and has the potential to be a predictor of DM of lung adenocarcinoma.

Emerging role of competing endogenous RNA in lung cancer drug resistance

Lung cancer remains one of the most common malignant cancers worldwide, and its survival rate is extremely low. Chemotherapy, the mainstay of lung cancer treatment, is not as effective as it could be due to the development of cellular resistance. The molecular mechanisms of drug resistance in lung cancer remain to be elucidated. Accumulating evidence suggests that ceRNAs are involved in various carcinogenesis and development. CeRNA is a transcript that regulates each other through competition with miRNA. However, the relationship between ceRNAs and chemoresistance in lung cancer remains unclear. In this narrative review, we provided a summary of treatment approaches that focus on ceRNA networks to overcome drug resistance.

Role of miRNAs as epigenetic regulators of immune checkpoints in lung cancer immunity

The advent of immunotherapy in cancer has provided new avenues in the treatment of many malignancies at various stages. Specifically, immune checkpoint inhibitors (ICIs) have transformed the field of lung cancer treatment. However, since some tumors can evade the immune system, not all patients respond properly. Recent research has provided evidence showing how microRNAs (miRNAs) are involved in regulating many immune checkpoints. MiRNAs have demonstrated their ability to modulate immune evasion of tumor cells. Currently, reliable markers are being sought to predict the efficacy of immunotherapy in these types of cancers. Therefore, the association of serum miRNAs and the response of ICIs in lung cancer is under study. Many miRNA molecules and their corresponding target genes have been identified in the regulation of chemoresistance. Therefore, elucidating how these miRNAs control the function of immune checkpoints, as well as the effectiveness of therapies based on ICIs set the basis for the development of new biomarkers to predict treatment response to ICIs. This chapter delves into the molecular role of miRNAs interacting with ICs, such as PD-1 and PD-L1, and the clinical utility of miRNAs, such as miR-16, miR-146a, and miR-335, in predicting treatment response to ICI-based therapy in lung cancer. The aim is to provide a deep insight of the current landscape, serving as a cornerstone for further research.

Circular RNAs in lung cancer: implications for preventing therapeutic resistance

LC is one of the most common malignant tumours that often presents with no distinct symptoms in the early stages, leading to late diagnoses when patients are at an advanced stage and no longer suitable for surgical treatment. Although adjuvant treatments are available, patients frequently develop tolerance to these treatments over time, resulting in poor prognoses for patients with advanced LC. Recently, circular RNAs (circRNAs), a type of non-coding RNA, have gained significant attention in LC research. Owing to their unique circular structure, circRNAs are highly stable within cells. This review systematically summarises the expression, characteristics, biological functions, and molecular regulatory mechanisms of circRNAs involved in therapy resistance as well as the potential applications in early diagnosis and gene targeting therapy in LC.

Identification of Circular RNAs as Biomarker Candidates in Lung Cancer Treatment

OBJECTIVE

Lung cancer is the most common malignancy and among the leading cause of cancer death worldwide. Therefore, there is an important need for biomarkers that can be used in the early diagnosis of the disease and in the follow-up of treatment. Circular RNAs (circRNAs) have a covalently closed circular structure that lacks 3' and 5' polar ends and is resistant to RNAase enzymes. Due to these properties, they can be stably found in body fluids. Therefore, they can serve as potential biomarkers in the diagnosis, monitoring of therapeutic response and prognosis of cancer. In our study, we aimed to investigate the expression levels of circRNA molecules in the treatment of lung cancer and to determine those that have the potential to be biomarkers.

METHODS

In this in vitro study, expression levels of 163 circRNAs were investigated in A549 cells, a non-small cell lung cancer cell line, before and after treatment with carboplatin and pemetrexed. Total RNA isolation and cDNA synthesis were performed after treatments. Expression levels of circRNA genes were determined by RT-qPCR method with the designed divergent primer sequences.

RESULTS

The study revealed the characterisation of differentially expressed circRNAs by treatment in lung cancer cells. Of them, hsa_circ_0001320 is not expressed in cancer cells, is expressed only after treatment, and increased the level of its expression in response to combination therapy.

CONCLUSION

As a result, while carboplatin, pemetrexed, and combined drug applications changed the expression levels of some circRNAs in lung cancer cells, some circRNAs were expressed only after treatment. In treatment follow-up and management, hsa_circ_0001320 has been identified as potential biomarker candidate.

Serum Exosomes-Based Biomarker circ_0008928 Regulates Cisplatin Sensitivity, Tumor Progression, and Glycolysis Metabolism by miR-488/HK2 Axis in Cisplatin-Resistant Nonsmall Cell Lung Carcinoma

Background: Nonsmall cell lung carcinoma (NSCLC) is a major cause of cancer-related death worldwide. The resistance of NSCLC to chemical drugs, such as cisplatin (CDDP), poses a heavy burden for NSCLC therapy. Herein, the effects of circular_0008928 (circ_0008928) on the CDDP sensitivity and biological behavior of CDDP-resistant NSCLC cells and underlying mechanism are revealed. Materials and Methods: The expression of circ_0008928 and microRNA-488 (miR-488) was detected by quantitative real-time polymerase chain reaction. The expression of hexokinase 2 (HK2) protein and exosome-specific proteins was determined by Western blot. The half-maximal inhibitory concentration (IC50) value of CDDP was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell proliferation and migratory and invasive abilities were illustrated by cell counting kit-8 and transwell assays. Cell glycolysis metabolism was illustrated by extracellular acidification rate assay, glucose kit and lactate kit assays and Western blot analysis. The binding sites between miR-488 and circ_0008928 or HK2 were predicted by starbase or microT-CDS online database, and identified by dual-luciferase reporter and RNA immunoprecipitation assays. Results: Circ_0008928 expression and HK2 protein expression were significantly upregulated, while miR-488 expression was obviously downregulated in NSCLC cells and CDDP-resistant NSCLC cells. Circ_0008928 expression was increased in serum exosomes of CDDP-resistant NSCLC patients compared with CDDP-sensitive NSCLC patients. In addition, circ_0008928 silencing improved CDDP sensitivity and attenuated CDDP-induced cell proliferation, migration, invasion, and glycolysis metabolism. Circ_0008928 was a sponge of miR-488, and miR-488 bound to HK2 in CDDP-resistant NSCLC cells. Furthermore, both miR-488 inhibitor and HK2 overexpression attenuated circ_0008928 absence-mediated impacts on CDDP sensitivity and tumor process in CDDP-resistant NSCLC. Conclusions: Circ_0008928 knockdown improved CDDP sensitivity and hindered cell proliferation, migration, invasion, and glycolysis metabolism by miR-488/HK2 axis in CDDP-resistant NSCLC. This finding provides a new mechanism for studying CDDP-resistant therapy in NSCLC.

Circ_0030411 aggravates cisplatin-resistance in non-small cell lung cancer by serving as a miR-495-3p sponge to enhance CCND1 expression

Circular RNAsplay important modulators in cisplatin (DDP) resistant non-small cell lung cancer (NSCLC). Herein, the role and mechanism of circ_0030411 in DDP-resistant NSCLC was explored. Circ_0030411, miR-495-3p, CCND1, PCNA, Bax, E-cadherin, and ki-67 expression were examined byqRT-PCR, western blot and IHC. DDP resistance, cell proliferation, apoptosis, and motility were assessed usingCCK, EdU flow cytometry, and transwell. Xenograft tumour model was established to explore the role of circ_0030411 in DDP-resistant NSCLC. Interaction between miR-495-3p and circ_0030411 or CCND1 wasverified via luciferase reporterand RIP. Circ_0030411 and CCND1 were increased in DDP-resistant NSCLC tissues and cells, andmiR-495-3p level was decreased. Circ_0030411 knockdown hindered cell growth, migration, invasion, in DDP-resistant NSCLC cells, and improved DDP sensitivityof NSCLC in vivo. Mechanistically, circ_0030411 acted as a sponge of miR-495-3p to affect CCND1expression. Circ_0030411 facilitated DDP resistance by regulating the miR-495-3p/CCND1 axis, highlighting a promising target for NSCLC patients.

Circ_0005615 Regulates the Progression of Colorectal Cancer Through the miR-873-5p/FOSL2 Signaling Pathway

To determine the effects of circ_0005615 in CRC development and underneath mechanism. The expression levels of circ_0005615, microRNA-873-5p (miR-873-5p) and FOS-like antigen 2 (FOSL2) mRNA were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of exosome makers, proliferation-related makers and FOSL2 were detected by western blot or immunohistochemistry assay. Cell proliferation was evaluated by cell counting kit-8 (CCK-8) and cell colony formation assays. Cell migration and invasion were demonstrated by a transwell assay. Cell apoptosis was investigated by flow cytometry analysis. The binding relationship between miR-873-5p and circ_0005615 or FOSL2 was predicted by circular RNA interactome and targetscan online databases, respectively, and identified by dual-luciferase reporter assay. The impacts of circ_0005615 silencing on tumor formation were determined by in vivo tumor formation assay. Circ_0005615 expression was dramatically upregulated in serum exosomes of CRC patients compared with the control group. The CRC patients with a high circ_0005615 expression had a poor survival rate. Circ_0005615 and FOSL2 expressions were apparently increased, while miR-873-5p was decreased in CRC tissues or cells relative to control groups. Circ_0005615 knockdown inhibited cell proliferation, migration, and invasion, whereas promoted cell apoptosis in CRC; however, miR-873-5p inhibitor attenuated these impacts. Additionally, circ_0005615 acted as a sponge of miR-873-5p and miR-873-5p bound to FOSL2. FOSL2 overexpression restrained the effects of miR-873-5p mimic on CRC progression. Furthermore, circ_0005615 knockdown suppressed tumor growth in vivo. Circ_0005615 modulated CRC malignant progression by controlling FOSL2 expression through sponging miR-873-5p. This finding lays a foundation for the study on circRNA-mediated CRC therapy.

Deciphering the Enigmatic Influence: Non-Coding RNAs Orchestrating Wnt/β-Catenin Signaling Pathway in Tumor Progression

Dysregulated expression of specific non-coding RNAs (ncRNAs) has been strongly linked to tumorigenesis, cancer progression, and therapeutic resistance. These ncRNAs can act as either oncogenes or tumor suppressors, thereby serving as valuable diagnostic and prognostic markers. Numerous studies have implicated the participation of ncRNAs in the regulation of diverse signaling pathways, including the pivotal Wnt/β-catenin signaling pathway that is widely acknowledged for its pivotal role in embryogenesis, cellular proliferation, and tumor biology control. Recent emerging evidence has shed light on the capacity of ncRNAs to interact with key components of the Wnt/β-catenin signaling pathway, thereby modulating the expression of Wnt target genes in cancer cells. Notably, the activity of this pathway can reciprocally influence the expression levels of ncRNAs. However, comprehensive analysis investigating the specific ncRNAs associated with the Wnt/β-catenin signaling pathway and their intricate interactions in cancer remains elusive. Based on these noteworthy findings, this review aims to unravel the intricate associations between ncRNAs and the Wnt/β-catenin signaling pathway during cancer initiation, progression, and their potential implications for therapeutic interventions. Additionally, we provide a comprehensive overview of the characteristics of ncRNAs and the Wnt/β-catenin signaling pathway, accompanied by a thorough discussion of their functional roles in tumor biology. Targeting ncRNAs and molecules associated with the Wnt/β-catenin signaling pathway may emerge as a promising and effective therapeutic strategy in future cancer treatments.

CircRNA B cell linker regulates cisplatin sensitivity in nonsmall cell lung cancer via microRNA-25-3p/BarH‑like homeobox 2 axis

Cisplatin (DDP) was a commonly used drug in the treatment of nonsmall cell lung cancer (NSCLC). However, the current resistance of patients to DDP seriously affected its therapeutic effect. Circular RNAs (circRNAs) have been reported to regulate drug resistance in cells. The purpose of this paper is to study the effect of circRNA B cell linker (circ_BLNK) in DDP resistance of NSCLC. The abundances of circ_BLNK, microRNA-25-3p (miR-25-3p) and BarH‑like homeobox 2 (BARX2) were examined by quantitative real-time PCR and western blot analysis. Cell proliferation and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, EdU assay and flow cytometry. Transwell assay was applied to assess cell migration and invasion. Protein levels were quantified by western blot analysis. Dual-luciferase reporter assay was enforced to confirm the links among circ_BLNK, miR-25-3p and BARX2. The mice models were enforced to evaluate tumorigenicity. Herein, circ_BLNK and BARX2 were lower-expressed, whereas miR-25-3p was higher-expressed in A549/DDP and H1299/DDP cells than their homologous parental NSCLC cells. Circ_BLNK increases improved DDP sensitivity of NSCLC cells by promoting cell apoptosis and inhibiting proliferation, migration and invasion. Moreover, we confirmed that circ_BLNK regulated BARX2 by inhibiting miR-25-3p. Accordingly, overexpression of circ_BLNK improved DDP sensitivity of NSCLC cells via miR-25-3p/BARX2 axis. Besides, circ_BLNK reduced cell resistance to DDP, thereby inhibiting tumor development in mice. Circ_BLNK promoted the DDP sensitivity of NSCLC via regulating miR-25-3p/BARX2 axis.

Circular RNAs: New layer of complexity evading breast cancer heterogeneity

Advances in high-throughput sequencing techniques and bioinformatic analysis have refuted the "junk" RNA hypothesis that was claimed against non-coding RNAs (ncRNAs). Circular RNAs (circRNAs); a class of single-stranded covalently closed loop RNA molecules have recently emerged as stable epigenetic regulators. Although the exact regulatory role of circRNAs is still to be clarified, it has been proven that circRNAs could exert their functions by interacting with other ncRNAs or proteins in their own physiologically authentic environment, regulating multiple cellular signaling pathways and other classes of ncRNAs. CircRNAs have also been reported to exhibit a tissue-specific expression and have been associated with the malignant transformation process of several hematological and solid malignancies. Along this line of reasoning, this review aims to highlight the importance of circRNAs in Breast Cancer (BC), which is ranked as the most prevalent malignancy among females. Notwithstanding the substantial efforts to develop a suitable anticancer therapeutic regimen against the heterogenous BC, inter- and intra-tumoral heterogeneity have resulted in an arduous challenge for drug development research, which in turn necessitates the investigation of other markers to be therapeutically targeted. Herein, the potential of circRNAs as possible diagnostic and prognostic biomarkers have been highlighted together with their possible application as novel therapeutic targets.

Circ_0043256 upregulates KLF2 expression by absorbing miR-1206 to suppress the tumorigenesis of lung cancer

BACKGROUND

Circular RNAs (circRNAs) have been reported to play roles in lung cancer development. The purpose of this work was to explore the function and mechanism of circ_0043256 in lung cancer tumorigenesis.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were used for the detection of the levels of genes and proteins. Cell growth, angiogenesis ability, migration, and invasion were analyzed by using 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, tube formation assay, transwell assay, and murine xenograft model, respectively. The target between miR-1206 and circ_0043256 or Krüppel-like factor 2 (KLF2) was verified by dual-luciferase reporter assay.

RESULTS

Circ_0043256 was a stable circRNA, which was found to be decreased in lung cancer tissues and cells. Functionally, forced expression of circ_0043256 suppressed lung cancer cell growth, angiopoiesis, migration, and invasion. Mechanistically, circ_0043256 directly bound to miR-1206 and miR-1206 targeted KLF2, circ_0043256 could regulate KLF2 expression via absorbing miR-1206. Rescue assay showed that miR-1206 overexpression reversed the anticancer effects of circ_0043256 on lung cancer cells. Moreover, inhibition of miR-1206 could suppress the malignant phenotypes of lung cancer cells, which was attenuated by KLF2 knockdown. Pre-clinically, lentivirus-mediated circ_0043256 overexpression impeded lung cancer growth in nude mice.

CONCLUSION

Forced expression of circ_0043256 could impede the tumorigenesis of lung cancer via miR-1206/KLF2 axis, indicating a potential therapeutic approach for lung cancer.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Anesthetic propofol suppresses growth and metastasis of lung adenocarcinoma in vitro through downregulating circ-MEMO1-miR-485-3p-NEK4 ceRNA axis

BACKGROUND

Recently, circular RNAs (circRNAs) have been emerging as new regulators in the propofol-induced tumor-suppressive role. Here, we intended to investigate the involvement of circRNA-Mediator of cell motility 1 (circ-MEMO1; hsa_circ_0007385) in propofol role in cancer hallmarks of lung adenocarcinoma (LUAD).

METHODS

Real-time quantitative PCR and western blotting examined transcriptional and translational levels of circ-MEMO1, microRNA (miR)-485-3p, and NIMA-related kinase-4 (NEK4), and markers of growth and metastasis including E-cadherin, CyclinD1, and Vimentin. Cancer hallmarks were measured by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, 5-ethynyl-2-deoxyuridine assay, and transwell assay. The interaction among circ-MEMO1, miR-485-3p, NEK4 was determined by dual-luciferase reporter assay and Pearson's correlation analysis.

RESULTS

Circ-MEMO1 and NEK4 were high-expressed, and miR-485-3p was low-expressed in LUAD patients and cells; moreover, circ-MEMO1 and NEK4 expression in LUAD cells could be suppressed, whereas miR-485-3p could be elevated with propofol anesthesia. Functionally, propofol restrained cell viability, cell cycle entrance, cell proliferation, migration, and invasion of LUAD cells, accompanied by promoted E-cadherin and depressed CyclinD1 and Vimentin. Coincidently, high circ-MEMO1 was associated with low overall survival of LUAD patients, and overexpressing circ-MEMO1 could overall attenuate propofol effects in LUAD cells. Of note, upregulating miR-485-3p and/or interfering NEK4 could partially countermand the adverse impacts of circ-MEMO1 on propofol's role in LUAD cells. Importantly, circ-MEMO1 acted as a sponge for miR-485-3p to modulate the expression of miR-485-3p-targeted oncogene NEK4.

CONCLUSION

Promoting the circ-MEMO1-miR-485-3p-NEK4 axis might halt the tumor-inhibiting role of propofol in LUAD cells in vitro, suggesting a potential epigenetic pathway of propofol.

Circ_0008285 knockdown represses tumor development by miR-384/RRM2 axis in hepatocellular carcinoma

INTRODUCTION AND OBJECTIVES

Circular RNA (circRNA) has attracted extensive attention in studies related to the malignant progression of cancer, including hepatocellular carcinoma (HCC). Therefore, its molecular mechanism in HCC needs to be further explored.

MATERIALS AND METHODS

The expression levels of circ_0008285, microRNA (miR)-384 and ribonucleotide reductase subunit M2 (RRM2) mRNA were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was analyzed using cell counting kit-8 assay and 5-ethynyl-2'-deoxyuridine assay, cell apoptosis was analyzed by flow cytometry, and cell migration and invasion were detected by transwell assay. Protein level was detected by western blot. The relationships between miR-384 and circ_0008285 or RRM2 were predicted by bioinformatics software and validated by dual luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

RESULTS

Circ_0008285 expression is elevated to HCC tissues and cell lines. Silencing of circ_0008285 inhibited the proliferation, migration and invasion of HCC cells but accelerated cell apoptosis in vitro and impeded HCC tumorigenesis in vivo. Mechanistically, circ_0008285 directly interacted with miR-384, and miR-384 silencing attenuated the effects of circ_0008285 interference on cell proliferation, migration, invasion, and apoptosis. RRM2 was a direct target of miR-384, and RRM2 overexpression reversed the effects of miR-384 overexpression on cell proliferation, migration, invasion, and apoptosis. In addition, circ_0008285 regulated RRM2 expression by sponging miR-384.

CONCLUSION

In this study, circ_0008285 could promote the malignant biological behaviors of HCC cells through miR-384/RRM2 axis and has the potential to become a therapeutic target for HCC, providing a new idea for targeted therapy of HCC.

The function and clinical implication of circular RNAs in lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide. Despite the recent advent of promising new targeted therapies, lung cancer diagnostic strategies still have difficulty in identifying the disease at an early stage. Therefore, the characterizations of more sensible and specific cancer biomarkers have become an important goal for clinicians. Circular RNAs are covalently close, endogenous RNAs without 5' end caps or 3'poly (A) tails and have been characterized by high stability, abundance, and conservation as well as display cell/tissue/developmental stage-specific expressions. Numerous studies have confirmed that circRNAs act as microRNA (miRNA) sponges, RNA-binding protein, and transcriptional regulators; some circRNAs even act as translation templates that participate in multiple pathophysiological processes. Growing evidence have confirmed that circRNAs are involved in the pathogenesis of lung cancers through the regulation of proliferation and invasion, cell cycle, autophagy, apoptosis, stemness, tumor microenvironment, and chemotherapy resistance. Moreover, circRNAs have emerged as potential biomarkers for lung cancer diagnosis and prognosis and targets for developing new treatments. In this review, we will summarize recent progresses in identifying the biogenesis, biological functions, potential mechanisms, and clinical applications of these molecules for lung cancer diagnosis, prognosis, and targeted therapy.

Role of circular RNAs in the diagnosis, regulation of drug resistance and prognosis of lung cancer (Review)

Lung cancer is one of the most common malignant tumors in China and is the highest cause of mortality among male and female patients, both in urban and rural areas. A subset of patients with lung cancer only display chest tightness without any other obvious symptoms. This is because most symptoms do not manifest during the early stages of disease development. Consequently, most patients with lung cancer are diagnosed when the disease is in the advanced stages, when they are already unfit for surgical treatment. Furthermore, the prognosis of patients with lung cancer is poor. The 5-year survival rate of patients with stage IA lung cancer is 85%, compared with 6% in those with stage IV. This requires the development of strategies for early diagnosis, treatment and prognosis to improve the management of lung cancer. Circular RNAs (circRNAs) belong to a class of closed circular non-coding RNAs formed by reverse splicing of a precursor mRNA. These RNAs are highly stable, ubiquitously expressed, conserved, and show high specificity. CircRNAs regulate biological processes, such as the proliferation, differentiation and invasion of lung cancer cells. Therefore, they can be used as biomarkers for the early diagnosis and prognosis prediction of lung cancer, as well as novel targets for therapy design. In the present review, the biological characteristics and functions of circRNAs, as well as their application in the diagnosis, control of drug resistance and effect on the prognosis of patients with lung cancer, will be discussed.

Circ_0009035 regulates the progression of cervical cancer by targeting miR-1305/CREBRF axis

Circular RNAs (circRNAs) have a crucial role in the occurrence of many diseases, such as tumors. Yet the roles of circ_0009035 (circRACGAP1) in cervical cancer are not fully characterized. The expression levels of circRACGAP1, miR-1305 and cAMP-responsive element-binding protein 3 regulatory factor (CREBRF) were detected by using real-time quantitative PCR or western blot. Cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine, colony formation assay, transwell assay and tube formation assay were used to detect cell proliferation, migration and invasion and angiogenesis, respectively. Flow cytometry assay was used to analyze the cell apoptosis. Dual-luciferase reporter assay and RNA immunoprecipitation assay were performed to analyze the targeting about miR-1305 and circ_0009035 or CREBRF. Xenograft model was built to study the role of circ_0009035 in vivo. Immunohistochemistry was used to detect the expression of Ki67, epithelial cadherin and vimentin. First, we found that circ_0009035 expression was significantly upregulated in tumor cells and tissues; second, knockdown of circ_0009035 could inhibit cell proliferation, migration and invasion and promote cell apoptosis. Subsequently, circ_0009035 was found to be able to target miR-1305, and the expression of miR-1305 in tumor tissues and cells was significantly lower. MiR-1305 inhibitor could restore cell-related progression of cervical cancer inhibited by si-circ_0009035. Finally, miR-1305 could target CREBRF, and circ_0009035 could regulate CREBRF expression by targeting miR-1305, thereby affecting cervical cancer tumorigenesis. In summary, our study confirmed that circ_0009035 could influence the development of cervical cancer through the targeted regulation of miR-1305/CREBRF.

Advances in the Study of CircRNAs in Tumor Drug Resistance

Recent studies have revealed that circRNAs can affect tumor DNA damage and repair, apoptosis, proliferation, and invasion and influence the transport of intratumor substances by acting as miRNA sponges and transcriptional regulators and binding to proteins in a variety of ways. However, research on the role of circRNAs in cancer radiotherapy and chemoresistance is still in its early stages. Chemotherapy is a common approach to oncology treatment, but the development of tumor resistance limits the overall clinical efficacy of chemotherapy for cancer patients. The current study suggests that circRNAs have a facilitative or inhibitory effect on the development of resistance to conventional chemotherapy in a variety of tumors, suggesting that circRNAs may serve as a new direction for the study of antitumor drug resistance. In this review, we will briefly discuss the biological features of circRNAs and summarize the recent progression of the involvement of circRNAs in the development and pathogenesis of cancer chemoresistance.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

Knockdown of circRNA Paralemmin 2 Ameliorates Lipopolysaccharide-induced Murine Lung Epithelial Cell Injury by Sponging miR-330-5p to Reduce ROCK2 Expression

Previous data have reported the high expression of circRNA paralemmin 2 (circPALM2) in mice with acute lung injury (ALI). However, the role of circPALM2 in ALI pathogenesis remains unclear. The study aims to reveal the function of circPALM2 in ALI and the underlying mechanism. C57BL/6 J mice and murine lung epithelial-12 (MLE-12) cells were treated with lipopolysaccharide (LPS) to simulate ALI mouse and ALI cell models, respectively. Lung injury score and lung wet-to-dry ratio assays were used to evaluate the ALI mouse model. Quantitative real-time polymerase chain reaction and Western blot assays were implemented to analyze the expressions of circPALM2, microRNA-330-5p (miR-330-5p), rho-associated coiled-coil containing protein kinase 2 (ROCK2), and apoptosis-related markers. Cell viability, apoptosis, and the production of inflammatory cytokines were investigated by cell counting kit-8, flow cytometry, and enzyme-linked immunosorbent assays. The expressions of circPALM2 and ROCK2 were significantly increased, while miR-330-5p was decreased in ALI mice and LPS-induced MLE-12 cells compared with controls. LPS treatment inhibited cell viability but induced apoptosis, inflammatory cytokine production, and oxidative stress; however, these effects were attenuated after the combination of circPALM2 knockdown and LPS. CircPALM2 regulated LPS-caused MLE-12 cell damage by targeting miR-330-5p. Additionally, ROCK2, a target gene of miR-330-5p, participated in LPS-induced MLE-12 cell injury. Further, circPALM2 activated ROCK2 by associating with miR-330-5p. CircPALM2 modulated LPS-caused murine lung epithelial cell injury by the miR-330-5p/ROCK2 pathway, providing a therapeutic target for ALI.

The Role of Circular RNAs in the Drug Resistance of Cancers

Cancer is a major threat to human health and longevity. Chemotherapy is an effective approach to inhibit cancer cell proliferation, but a growing number of cancer patients are prone to develop resistance to various chemotherapeutics, including platinum, paclitaxel, adriamycin, and 5-fluorouracil, among others. Significant progress has been made in the research and development of chemotherapeutic drugs over the last few decades, including targeted therapy drugs and immune checkpoint inhibitors; however, drug resistance still severely limits the application and efficacy of these drugs in cancer treatment. Recently, emerging studies have emphasized the role of circular RNAs (circRNAs) in the proliferation, migration, invasion, and especially chemoresistance of cancer cells by regulating the expression of related miRNAs and targeted genes. In this review, we comprehensively summarized the potential roles and mechanisms of circRNAs in cancer drug resistance including the efflux of drugs, apoptosis, intervention with the TME (tumor microenvironment), autophagy, and dysfunction of DNA damage repair, among others. Furthermore, we highlighted the potential value of circRNAs as new therapeutic targets and prognostic biomarkers for cancer.

Circ_0007385 regulates cell proliferation, apoptosis and stemness via targeting miR-493-3p/RAB22A axis in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a common cancer in the United States. Previous studies have shown that circular RNAs (circRNAs) can affect NSCLC progression, but its regulatory mechanism is still indistinct. In this study, we unfold the roles of circular RNA_0007385 in NSCLC tissues and cells.

METHODS

Expression levels of circ_0007385, microRNA-493-3p (miR-493-3p) and Ras-related protein Rab-22A (RAB22A) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in NSCLC tissues and cells. Cell proliferation, apoptosis and stemness were examined by cell counting kit 8 (CCK8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry analysis and sphere-formation assay. The interaction between miR-493-3p and circ_0007385 or RAB22A was forecasted by bioinformatic analysis and detected by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and RNA pulldown assays. In vivo experiments were implemented to verify the effect of circ_0007385 in vivo.

RESULTS

Expression of circ_0007385 and RAB22A increased, whereas miR-493-3p level was decreased in NSCLC tissues in contrast to that in normal tissues. For functional analysis, circ_0007385 deficiency inhibited cell proliferation and stemness, whereas it promoted cell apoptosis in NSCLC cells. Mechanically, circ_0007385 acted as a miR-493-3p sponge to modulate RAB22A expression. Moreover, circ_0007385 could regulate the development of NSCLC by sponging miR-493-3p to regulate the expression of RAB22A. In addition, circ_0007385 silence also attenuated tumor growth in vivo.

CONCLUSIONS

Circ_0007385 promoted NSCLC progression by sponging miR-493-3p to increase RAB22A expression, which also offered an underlying targeted therapy for NSCLC treatment.

Exosomal circ_0007385 enhances non-small cell lung cancer cell proliferation and stemness via regulating miR-1253/FAM83A axis

Exosomes are critical mediators of intercellular communication in the tumor microenvironment. Exosomal circular RNAs (circRNAs) can act as biomarkers and play crucial roles in many cancers, including non-small cell lung cancer (NSCLC). The aim of this study was to explore the functions and regulatory mechanism of exosomal circ_0007385 in NSCLC. The expression levels of circ_0007385, microRNA-1253 (miR-1253), family with sequence similarity 83, member A (FAM83A) mRNA were determined by quantitative real-time PCR (qRT-PCR). Cell Counting Kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (Edu), and colony formation assays were utilized to determine cell proliferation ability. Sphere formation efficiency was determined by sphere formation assay. All protein levels were detected by western blot assay. Exosomes were detected using transmission electron microscopy analysis. Size distribution of exosomes was analyzed by nanoparticle tracking analysis. The interaction between miR-1253 and circ_0007385 or FAM83A was confirmed by dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays. Mice xenograft model was established to verify the function of circ_0007385 in vivo. Circ_0007385 was upregulated in NSCLC tissues and cells. Knockdown of circ_0007385 inhibited NSCLC cell proliferation and stemness, while exosomal circ_0007385 facilitated NSCLC cell proliferation and stemness. In addition, miR-1253 was a direct target of circ_0007385, and miR-1253 reversed the inhibitory effects of circ_0007385 on cell proliferation and stemness in NSCLC cells. Moreover, FAM83A was a direct target of miR-1253, and miR-1253 suppressed NSCLC cell proliferation and stemness by targeting FAM83A. Furthermore, circ_0007385 knockdown inhibited tumor growth in vivo. Exosomal circ_0007385 promoted NSCLC cell proliferation and stemness by regulating miR-1253/FAM83A axis.

MicroRNA-519d-3p antagonizes osteosarcoma resistance against cisplatin by targeting PD-L1

Accumulating evidence indicates that a ligand of programmed cell death receptor-1 (PD-L1) participates in the progression and recurrence of multiple malignancies, including osteosarcoma. Nevertheless, the role of PD-L1 in chemoresistance development is not fully understood. In the current study, we aim to clarify the interaction of miR-519d-3p and PD-L1 in the development of cisplatin resistance. Immunohistochemistry, quantitative reverse-transcription polymerase reaction, and Western blot were used to evaluate PD-L1 expression. MTT and transwell migration assays were used to measure cell growth and motility, respectively. ENCORI, miRCode, and miRDB databases were recruited to predict candidate miRNAs targeting PD-L1. The binding sequences of miR-519d-3p and PD-L1 3' untranslated region were identified by dual-luciferase reporter and RNA immunoprecipitation assays. Flow cytometric analysis was conducted to measure the cycle distribution and cell apoptosis. Metastatic mouse models were generated with cisplatin-resistant sublines by intravenous injection. We found that PD-L1 expression was positively correlated to cisplatin resistance and metastasis, whereas miR-519d-3p expression was reduced in cisplatin-resistant specimens and was negatively correlated to cisplatin resistance and metastasis of osteosarcoma. We demonstrated that miR-519d-3p overexpression reversed cisplatin resistance, induced G1/S phase arrest and apoptosis. In addition, we proved that miR-519d-3p inhibited lung metastasis by establishing cisplatin-resistant MG63 metastatic xenograft models. The present findings suggest that miR-519d-3p/PD-L1 axis is a novel signaling pathway contributing to cisplatin resistance. Our study provides new clues for curing refractory osteosarcoma beyond immune checkpoint inhibitors.

circ_CHFR regulates ox-LDL-mediated cell proliferation, apoptosis, and EndoMT by miR-15a-5p/EGFR axis in human brain microvessel endothelial cells

Oxidized low-density lipoprotein (ox-LDL) is a significant risk factor for various brain vascular diseases. Circular RNA (circRNA) is involved in the pathogenesis of brain vascular diseases. This study revealed the roles of circ_CHFR in ox-LDL-mediated cell proliferation, apoptosis, and endothelial-to-mesenchymal transition (EndoMT). Our results showed that circ_CHFR and EGFR expressions were dramatically upregulated, while miR-15a-5p expression was downregulated in ox-LDL-induced human brain microvessel endothelial cells (HBMECs) relative to control groups. circ_CHFR knockdown hindered the effects of ox-LDL exposure on cell proliferation, cell cycle, apoptosis, and EndoMT in HBMECs, whereas these impacts were abolished by miR-15a-5p inhibitor. In addition, circ_CHFR functioned as a sponge of miR-15a-5p and miR-15a-5p bound to EGFR. Thus, we concluded that circ_CHFR silencing hindered ox-LDL-mediated cell proliferation, apoptosis, and EndoMT by downregulating EGFR expression through sponging miR-15a-5p in HBMECs. Our findings provide a new mechanism for studying circRNA-directed therapy in ox-LDL-induced human brain vascular diseases.

Circular RNA erythrocyte membrane protein band 4.1 assuages ultraviolet irradiation-induced apoptosis of lens epithelial cells by stimulating 5'-bisphosphate nucleotidase 1 in a miR-24-3p-dependent manner

Apoptosis of lens epithelial cells contributed to the formation of age-related cataract (ARC), and previous data revealed that circular RNA (circRNA) was responsible for the underneath mechanism. The study was organized to explore the role of circular RNA erythrocyte membrane protein band 4.1 (circ_EPB41) in ultraviolet (UV) irradiation-induced apoptosis of lens epithelial cells. SRA01/04 cells were irradiated with UV to mimic the ARC cell model. The RNA levels of circ_EPB41, microRNA-24-3p (miR-24-3p), and 3ʹ(2ʹ), 5ʹ-bisphosphate nucleotidase 1 (BPNT1) were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. 5-Ethynyl-29-deoxyuridine, 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide and DNA content quantitation assays were performed to investigate cell proliferation. Flow cytometry was conducted to analyze cell apoptosis. Dual-luciferase reporter assay was implemented to confirm the interaction among circ_EPB41, miR-24-3p, and BPNT1. Our data showed that circ_EPB41 and BPNT1 expression were downregulated in ARC tissues and UV-irradiated SRA01/04 cells as compared with normal anterior lens capsules and untreated SRA01/04 cells. Circ_EPB41 overexpression ameliorated the effects of UV irradiation on the proliferation and apoptosis of SRA01/04 cells. Besides, miR-24-3p, a target miRNA of circ_EPB41, attenuated circ_EPB41 introduction-mediated proliferation, and apoptosis of UV-irradiated SRA01/04 cells. MiR-24-3p regulated UV irradiation-induced effects by targeting BPNT1. Importantly, it was found that circ_EPB41 stimulated BPNT1 production by miR-24-3p. Taken together, the enforced expression of circ_EPB41 ameliorated UV irradiation-induced apoptosis of lens epithelial cells by miR-24-3p/BPNT1 pathway, providing us with a potential target for the therapy of UV-caused ARC.

Long non-coding RNA PROX1-AS1 knockdown upregulates microRNA-519d-3p to promote chemosensitivity of retinoblastoma cells via targeting SOX2

OBJECTIVE

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) participate in tumor progression, while the role of PROX1-antisense RNA1 (PROX1-AS1) sponging miR-519d-3p in retinoblastoma (RB) remains largely unknown. We aim to explore the effect of the PROX1-AS1/miR-519d-3p/sex determining region Y-box 2 (SOX2) in chemosensitivity of RB cells.

METHODS

Expression of PROX1-AS1, miR-519d-3p and SOX2 in RB tissues and cells was determined. The drug-resistant cell lines were established and respectively intervened with PROX1-AS1 or miR-519d-3p expression to explore their roles in drug resistance and malignant behaviors of the drug-resistant cells. The binding relationships between PROX1-AS1 and miR-519d-3p, and between miR-519d-3p and SOX2 were evaluated.

RESULTS

PROX1-AS1 and SOX2 were upregulated while miR-519d-3p was downregulated in RB tissues and cells, especially in drug-resistant cells. The PROX1-AS1 inhibition or miR-519d-3p elevation suppressed the drug resistance, proliferation, migration and invasion, and promoted apoptosis of the drug-resistant RB cells. Moreover, PROX1-AS1 sponged miR-519d-3p and miR-519d-3p targeted SOX2.

CONCLUSION

PROX1-AS1 knockdown upregulates miR-519d-3p to promote chemosensitivity of RB cells via targeting SOX2.

Research Progress on the Functions and Mechanism of circRNA in Cisplatin Resistance in Tumors

Cisplatin is a common chemotherapeutic drug that has been used to treat of numerous tumors, including testicular, lung, bladder, ovarian, liver and head and neck cancers. Although clinical chemotherapy based on cisplatin has shown a remarkable therapeutic effect, the resistance to cisplatin becomes increasingly obvious as a patient uses it for a prolonged period. It not only affects the prognosis of these tumors, but also causes the recurrence of cancer and decreases the overall survival rate. The development of cisplatin resistance involves several mechanisms, including DNA damage repair, ATP-binding cassette (ABC) transporter, autophagy, cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), and other related signaling pathways. Interestingly, these mechanisms have been found to be influenced by circular RNAs (circRNAs) to regulate tumor proliferation, invasion, chemosensitivity, and other biological behaviors in the tumor microenvironment (TME). In recent years, circRNAs in cisplatin resistance in tumors, especially lung cancer and gastric cancer, have gradually drawn peoples' attention. This review summarizes recent studies on the functions and mechanisms of circRNAs in cisplatin resistance. We emphasize that circRNA can be used as a promising target gene to improve drug resistance and therapeutic efficacy.

CircASXL1 knockdown represses the progression of colorectal cancer by downregulating GRIK3 expression by sponging miR-1205

BACKGROUND

Colorectal cancer (CRC) is a common aggressive tumor that poses a heavy burden to human health. An increasing number of studies have reported that circular RNA (circRNA) is involved in the progression of CRC. In this study, the special profiles of circASXL1 (circ_0001136) in CRC progression were revealed.

METHODS

The expression of circASXL1, microRNA-1205 (miR-1205), and glutamate ionotropic receptor kainate type subunit 3 (GRIK3) mRNA was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression was determined by Western blot or immunohistochemistry. Cell colony-forming ability was investigated by colony formation assay. Cell cycle and apoptosis were demonstrated using cell-cycle and cell-apoptosis analysis assays, respectively. Cell migration and invasion were detected by wound-healing and transwell migration and invasion assays, respectively. The binding sites between miR-1205 and circASXL1 or GRIK3 were predicted by circBank or miRDB online database, and identified by dual-luciferase reporter assay. The impact of circASXL1 on tumor formation in vivo was investigated by in vivo tumor formation assay.

RESULTS

CircASXL1 and GRIK3 expression were apparently upregulated, and miR-1205 expression was downregulated in CRC tissues and cells relative to control groups. CircASXL1 knockdown inhibited cell colony-forming ability, migration and invasion, whereas induced cell arrest at G0/G1 phase and cell apoptosis in CRC cells; however, these effects were attenuated by miR-1205 inhibitor. Additionally, circASXL1 acted as a sponge for miR-1205, and miR-1205 was associated with GRIK3. Furthermore, circASXL1 silencing hindered tumor formation by upregulating miR-1205 and downregulating GRIK3 expression.

CONCLUSION

CircASXL1 acted an oncogenic role in CRC malignant progression via inducing GRIK3 through sponging miR-1205. Our findings provide a theoretical basis for studying circASXL1-directed therapy for CRC.

Damage-Associated Molecular Patterns Modulation by microRNA: Relevance on Immunogenic Cell Death and Cancer Treatment Outcome

Simple Summary

Inside the cell, damage-associated molecular pattern molecules (DAMPs) play several physiological functions, but when they are released or translocated to the extracellular space, they gain additional immunogenic roles. Thus, DAMPs are considered key hallmarks of immunogenic cell death (ICD) in cancer, a functionally unique regulated form of stress-mediated cell death that activates the immune system response against tumor cells. Several epigenetic modulators of DAMPs have been reported. In this review, we aimed to provide an overview of the effects of microRNAs (miRNAs) on the expression of DAMPs and the putative link between miRNA, DAMPs, and cell death, focused on ICD. Overall, we propose that miRNAs, by targeting DAMPs, play critical roles in the regulation of both cell death and immune-associated mechanisms in cancer, while evidence of their potential involvement in ICD is limited. Finally, we discuss emerging data regarding the impact of miRNAs’ modulation on cancer treatment outcome.

Abstract

Immunogenic cell death (ICD) in cancer is a functionally unique regulated form of stress-mediated cell death that activates both the innate and adaptive immune response against tumor cells. ICD makes dying cancer cells immunogenic by improving both antigenicity and adjuvanticity. The latter relies on the spatiotemporally coordinated release or exposure of danger signals (DAMPs) that drive robust antigen-presenting cell activation. The expression of DAMPs is often constitutive in tumor cells, but it is the initiating stressor, called ICD-inducer, which finally triggers the intracellular response that determines the kinetics and intensity of their release. However, the contribution of cell-autonomous features, such as the epigenetic background, to the development of ICD has not been addressed in sufficient depth. In this context, it has been revealed that several microRNAs (miRNAs), besides acting as tumor promoters or suppressors, can control the ICD-associated exposure of some DAMPs and their basal expression in cancer. Here, we provide a general overview of the dysregulation of cancer-associated miRNAs whose targets are DAMPs, through which new molecular mediators that underlie the immunogenicity of ICD were identified. The current status of miRNA-targeted therapeutics combined with ICD inducers is discussed. A solid comprehension of these processes will provide a framework to evaluate miRNA targets for cancer immunotherapy.

NSL2CD: identifying potential circRNA-disease associations based on network embedding and subspace learning

Many studies have evidenced that circular RNAs (circRNAs) are important regulators in various pathological processes and play vital roles in many human diseases, which could serve as promising biomarkers for disease diagnosis, treatment and prognosis. However, the functions of most of circRNAs remain to be unraveled, and it is time-consuming and costly to uncover those relationships between circRNAs and diseases by conventional experimental methods. Thus, identifying candidate circRNAs for human diseases offers new opportunities to understand the functional properties of circRNAs and the pathogenesis of diseases. In this study, we propose a novel network embedding-based adaptive subspace learning method (NSL2CD) for predicting potential circRNA-disease associations and discovering those disease-related circRNA candidates. The proposed method first calculates disease similarities and circRNA similarities by fully utilizing different data sources and learns low-dimensional node representations with network embedding methods. Then, we adopt an adaptive subspace learning model to discover potential associations between circRNAs and diseases. Meanwhile, an integrated weighted graph regularization term is imposed to preserve local geometric structures of data spaces, and L1,2-norm constraint is also incorporated into the model to realize the smoothness and sparsity of projection matrices. The experiment results show that NSL2CD achieves comparable performance under different evaluation metrics, and case studies further confirm its ability to discover potential candidate circRNAs for human diseases.

Circular RNAs: new biomarkers of chemoresistance in cancer

Chemotherapeutics are validated conventional treatments for patients with advanced cancer. However, with continual application of chemotherapeutics, chemoresistance, which is often predictive of poor prognosis, has gradually become a concern in recent years. Circular RNAs (circRNAs), a class of endogenous noncoding RNAs (ncRNAs) with a closed-loop structure, have been reported to be notable targets and markers for the prognosis, diagnosis, and treatment of many diseases, particularly cancer. Although dozens of studies have shown that circRNAs play major roles in drug-resistance activity in tumors, the mechanisms by which circRNAs affect chemoresistance have yet to be explored. In this review, we describe the detailed mechanisms of circRNAs and chemotherapeutics in various cancers and summarize potential therapeutic targets for drug-resistant tumors.

LncRNA BLACAT1/miR-519d-3p/CREB1 Axis Mediates Proliferation, Apoptosis, Migration, Invasion, and Drug-Resistance in Colorectal Cancer Progression

BACKGROUND

Colorectal cancer (CRC) is a common severe disease around the world. The merging papers reported that long noncoding RNAs (lncRNAs) took part in the diversified pathological processes of CRC. This study aimed to uncover the role and the potential mechanism of lncRNA bladder cancer-associated transcript 1 (BLACAT1) in CRC progression.

METHODS

LncRNA BLACAT1, micro-519d-3p (miR-519d-3p), and cAMP-responsive element binding protein 1 (CREB1) levels were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in CRC tissues and cells. The bio-functional effects were examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry assay, and transwell assay. The susceptibility testing was determined by oxaliplatin (OXA) administration. The potential binding sites between miR-519d-3p and BLACAT1 or CREB1 were predicted by online software starBase and confirmed by dual-luciferase reporter analysis. The relative proteins expression in CRC cells was determined by Western blot analysis. Xenograft tumor model was used to evaluate biological function of BLACAT1 in vivo.

RESULTS

The expression of BLACAT1 was promoted in CRC tissues and cells, and correlated to the TNM (tumor, node, metastasis) stage, distant metastasis, and overall survival rate. Silencing of BLACAT1 limited the proliferation, migration, and invasion, facilitated the apoptosis, and re-sensitized OXA-resistance in CRC cells. MiR-519d-3p was a target of BLACAT1. Furthermore, miR-519d-3p deletion reversed the positive effects of BLACAT1 deletion on CRC cells. Moreover, our data showed that miR-519d-3p directly targeted CREB1 and BLACAT1 sponged miR-519d-3p to regulate CREB1 expression. Besides, CREB1 disrupted the bio-functional results above from BLACAT1 suppression. Additionally, BLACAT1 knockdown promoted CRC cells sensitivity to OXA in vivo.

CONCLUSION

BLACAT1 mediated the progression of CRC and OXA-resistance by miR-519d-3p/CREB1 axis.

Long Noncoding RNA LINC01426 Sequesters microRNA-519d-5p to Promote Non-Small Cell Lung Cancer Progression by Increasing ETS1 Expression

PURPOSE

Recent studies have identified important roles for long intergenic non-protein coding RNA 1426 (LINC01426) in glioma and clear cell renal cell carcinoma. The present study evaluated the expression profile of LINC01426 in non-small cell lung cancer (NSCLC) tissues and cell lines. Furthermore, the function of LINC01426 in NSCLC and the molecular mechanisms involved were extensively studied.

METHODS

The abundance of LINC01426 in NSCLC tissues and cell lines was determined using quantitative reverse transcription-polymerase chain reaction. The cell counting kit-8 assay, flow cytometry, transwell experiments for migration and invasion, and xenograft tumor model were used to assess the function of LINC01426 in NSCLC cells. Mechanistic studies were performed using the luciferase reporter assay and RNA immunoprecipitation.

RESULTS

Significant LINC01426 upregulation was observed in NSCLC tissues and cell lines. Silencing LINC01426 inhibited proliferation, migration, and invasion of NSCLC cells and facilitated cell apoptosis in vitro. Furthermore, interference of LINC01426 restricted tumor growth of NSCLC cells in vivo. In addition, LINC01426 showed the ability to directly bind to microRNA-519d-5p (miR-519d-5p) and act as a molecular sponge for miR-519d-5p in NSCLC cells. Furthermore, the ETS proto-oncogene 1 (ETS1) was identified as a direct target of miR-519d-5p and LINC01426 could indirectly upregulate ETS1 expression by sponging miR-519d-5p. Moreover, the cancer-inhibiting activities of LINC01426 knockdown in NSCLC cells were partially offset by miR-519d-5p inhibition.

CONCLUSION

LINC01426 increases ETS1 expression by sequestering miR-519d-5p, thereby aggravating the malignant progression of NSCLC. The LINC01426/miR-519d-5p/ETS1 competing endogenous RNA pathway may provide a target for designing therapeutic agents for NSCLC treatment.

LncRNA HCP5 Promotes Cell Invasion and Migration by Sponging miR-29b-3p in Human Bladder Cancer

BACKGROUND

Bladder cancer (BC) is one of the most common malignant tumors in the urinary system. In this study, the roles of lncRNA HCP5 (human major histocompatibility complex p5) and miR-29b-3p in human BC were investigated. Their regulations involved in cell invasion and migration were also evaluated.

METHODS

Luciferase reporter assay was performed to detect the binding between miR-29b-3p and HCP5 or high-mobility group box 1 (HMGB1). Cell viability, migration, invasion and apoptosis were assessed by CCK-8, colony formation, transwell assay and flow cytometry, respectively. Expression levels of HMGB1/toll-like receptor 4 (TLR4) proteins were measured by Western blot. Xenograft model was built, and tumor volumes and weights were calculated.

RESULTS

The results revealed dysregulation of HCP5 and miR-29b-3p in BC samples and cells. HCP5 negatively regulated the expression of miR-29b-3p and enhanced cell viability, migration and invasion. MiR-29b-3p mediated the effect of HCP5 on cell viability, proliferation, migration and invasion in RT4 cells. In addition, miR-29b-3p could regulate the expression of HMGB1 through interaction with HMGB1.

CONCLUSION

The findings in this study supported that lncRNA HCP5 could promote cell invasion and migration by sponging miR-29b-3p in human BC.

Knockdown of hsa_circ_0037658 inhibits the progression of osteoarthritis via inducing autophagy

Osteoarthritis (OA) is a chronic musculoskeletal degeneration disease that can result in chronic pain and functional disability. Circular RNAs (CirRNAs) are known to be involved in OA. It was reported that hsa_circ_0037658 was notably upregulated in OA tissues; however, the biological role of hsa_circ_0037658 in OA remains unclear. To investigate the function of hsa_circ_0037658 in OA, CHON-001 cells were treated with IL-1β. The effect of hsa_circ_0037658 knockdown on cell growth was tested by CCK-8 and immunofluorescence staining. In addition, the correlation between hsa_circ_0037658 and autophagy was explored by LC3 staining and western blot. The results indicated that hsa_circ_0037658 was significantly upregulated in IL-1β-treated CHON-001 cells. The silencing of hsa_circ_0037658 could protect CHON-001 cell injury against IL-1β. Moreover, hsa_circ_0037658 shRNA reversed IL-1β-induced cell growth inhibition via inducing cell autophagy. Furthermore, knockdown of hsa_circ_0037658 notably alleviated the symptom of OA in vivo. To sum up, knockdown of hsa_circ_0037658 suppressed the progression of OA via inducing autophagy. Thus, hsa_circ_0037658 might serve as a potential target for the treatment of OA.