CircRNA CDR1as/miR-641/HOXA9 pathway regulated stemness contributes to cisplatin resistance in non-small cell lung cancer (NSCLC)

Emerging roles of CircRNA-miRNA networks in cancer development and therapeutic response

The complex interplay of epigenetic factors is essential in regulating the hallmarks of cancer and orchestrating intricate molecular interactions during tumor progression. Circular RNAs (circRNAs), known for their covalently closed loop structures, are non-coding RNA molecules exceptionally resistant to enzymatic degradation, which enhances their stability and regulatory functions in cancer. Similarly, microRNAs (miRNAs) are endogenous non-coding RNAs with linear structures that regulate cellular biological processes akin to circRNAs. Both miRNAs and circRNAs exhibit aberrant expressions in various cancers. Notably, circRNAs can function as sponges for miRNAs, influencing their activity. The circRNA/miRNA interaction plays a pivotal role in the regulation of cancer progression, including in brain, gastrointestinal, gynecological, and urological cancers, influencing key processes such as proliferation, apoptosis, invasion, autophagy, epithelial-mesenchymal transition (EMT), and more. Additionally, this interaction impacts the response of tumor cells to radiotherapy and chemotherapy and contributes to immune evasion, a significant challenge in cancer therapy. Both circRNAs and miRNAs hold potential as biomarkers for cancer prognosis and diagnosis. In this review, we delve into the circRNA-miRNA circuit within human cancers, emphasizing their role in regulating cancer hallmarks and treatment responses. This discussion aims to provide insights for future research to better understand their functions and potentially guide targeted treatments for cancer patients using circRNA/miRNA-based strategies.

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.

Value of CDR1-AS as a predictive and prognostic biomarker for patients with breast cancer receiving neoadjuvant chemotherapy in a prospective Chinese cohort

BACKGROUND

Neoadjuvant chemotherapy (NAC) is an effective treatment for locally advanced breast cancer (BC). However, there are no effective biomarkers for evaluating its efficacy. CDR1-AS, well known for its important role in tumorigenesis, is a famous circular RNA involved in the chemosensitivity of cancers other than BC. However, the predictive role of CDR1-AS in the efficacy and prognosis of NAC for BC has not been fully elucidated. We herein aimed to clarify this role.

METHODS

The present study included patients treated with paclitaxel-cisplatin-based NAC. The expression of CDR1-AS was detected by real-time quantitative reverse transcription polymerase chain reaction testing. The predictive value of CDR1-AS expression was examined in pathological complete response (pCR) after NAC using logistic regression analysis. The relationship between CDR1-AS expression and survival was demonstrated using the Kaplan-Meier method, and tested by log-rank test and Cox proportional hazards regression model.

RESULTS

The present study enrolled 106 patients with BC. Multivariate logistic regression analysis revealed that CDR1-AS expression was an independent predictive factor for pCR (odds ratio [OR] = 0.244; 95% confidence interval [CI] 0.081-0.732; p = 0.012). Furthermore, pCR benefits with low CDR1-AS expression were observed across all subgroups. The Kaplan-Meier curves and log-rank test suggested that the CDR1-AS high-expression group showed significantly better disease-free survival (DFS; log-rank p = 0.022) and relapse-free survival (RFS; log-rank p = 0.012) than the CDR1-AS low-expression group. Multivariate analysis revealed that CDR1-AS expression was an independent prognostic factor for DFS (adjusted HR = 0.177; 95% CI 0.034-0.928, p = 0.041), RFS (adjusted HR = 0.061; 95% CI 0.006-0.643, p = 0.020), and distant disease-free survival (adjusted HR = 0.061; 95% CI 0.006-0.972, p = 0.047).

CONCLUSIONS

CDR1-AS may be a potential novel predictive biomarker of pCR and survival benefit in patients with locally advanced BC receiving NAC. This may help identify specific chemosensitive individuals and build personalized treatment strategies.

Role of homeobox genes in cancer: immune system interactions, long non-coding RNAs, and tumor progression

The intricate interplay between Homeobox genes, long non-coding RNAs (lncRNAs), and the development of malignancies represents a rapidly expanding area of research. Specific discernible lncRNAs have been discovered to adeptly regulate HOX gene expression in the context of cancer, providing fresh insights into the molecular mechanisms that govern cancer development and progression. An in-depth comprehension of these intricate associations may pave the way for innovative therapeutic strategies in cancer treatment. The HOX gene family is garnering increasing attention due to its involvement in immune system regulation, interaction with long non-coding RNAs, and tumor progression. Although initially recognized for its crucial role in embryonic development, this comprehensive exploration of the world of HOX genes contributes to our understanding of their diverse functions, potentially leading to immunology, developmental biology, and cancer research discoveries. Thus, the primary objective of this review is to delve into these aspects of HOX gene biology in greater detail, shedding light on their complex functions and potential therapeutic applications.

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.

Examining the evidence for mutual modulation between m6A modification and circular RNAs: current knowledge and future prospects

The resistance of cancer cells to treatment significantly impedes the success of therapy, leading to the recurrence of various types of cancers. Understanding the specific mechanisms of therapy resistance may offer novel approaches for alleviating drug resistance in cancer. Recent research has shown a reciprocal relationship between circular RNAs (circRNAs) and N6-methyladenosine (m6A) modification, and their interaction can affect the resistance and sensitivity of cancer therapy. This review aims to summarize the latest developments in the m6A modification of circRNAs and their importance in regulating therapy resistance in cancer. Furthermore, we explore their mutual interaction and exact mechanisms and provide insights into potential future approaches for reversing cancer resistance.

New insights into the potential of exosomal circular RNAs in mediating cancer chemotherapy resistance and their clinical applications

Chemotherapy resistance typically leads to tumour recurrence and is a major obstacle to cancer treatment. Increasing numbers of circular RNAs (circRNAs) have been confirmed to be abnormally expressed in various tumours, where they participate in the malignant progression of tumours, and play important roles in regulating the sensitivity of tumours to chemotherapy drugs. As exosomes mediate intercellular communication, they are rich in circRNAs and exhibit a specific RNA cargo sorting mechanism. By carrying and delivering circRNAs, exosomes can promote the efflux of chemotherapeutic drugs and reduce intracellular drug concentrations in recipient cells, thus affecting the cell cycle, apoptosis, autophagy, angiogenesis, invasion and migration. The mechanisms that affect the phenotype of tumour stem cells, epithelial-mesenchymal transformation and DNA damage repair also mediate chemotherapy resistance in many tumours. Exosomal circRNAs are diagnostic biomarkers and potential therapeutic targets for reversing chemotherapy resistance in tumours. Currently, the rise of new fields, such as machine learning and artificial intelligence, and new technologies such as biosensors, multimolecular diagnostic systems and platforms based on circRNAs, as well as the application of exosome-based vaccines, has provided novel ideas for precision cancer treatment. In this review, the recent progress in understanding how exosomal circRNAs mediate tumour chemotherapy resistance is reviewed, and the potential of exosomal circRNAs in tumour diagnosis, treatment and immune regulation is discussed, providing new ideas for inhibiting tumour chemotherapy resistance.

CircHIF1A induces cetuximab resistance in colorectal cancer by promoting HIF1α-mediated glycometabolism alteration

Epidermal growth factor receptor (EGFR)-targeted therapy is an important treatment for RAS wild-type metastatic colorectal cancer (mCRC), but the resistance mechanism remains unclear. Here, the differential expression of circRNAs between Cetuximab sensitive and resistant cell lines was analyzed using whole-transcriptome sequencing. We identified that the expression of circHIF1A was significantly higher in LIM1215-R than in LIM1215. When treated with Cetuximab, downregulation of circHIF1A level weakened the proliferation and clonal formation ability of LIM1215-R, caused more cells to enter G0-G1 phase, and significantly reduced the basal respiration, ATP production, and maximal respiration, as well as the glycolytic capacity and glycolytic reserve. The response rate and prognosis of circHIF1A-positive patients were inferior to those of negative patients. Mechanistically, circHIF1A can upregulate the level of hypoxia-inducible factor 1 A (HIF1A) by competitively binding to miR-361-5p, inducing the overexpression of enzymes such as glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA). In a xenograft model, inhibition of circHIF1A expression increased the sensitivity to Cetuximab treatment. In conclusion, circHIF1A can promote HIF1α-mediated glycometabolism alteration to induce Cetuximab resistance in CRC. It has the potential to become a screening indicator for the Cetuximab beneficial population in mCRC and a new therapeutic target for enhancing treatment efficacy.

Deciphering the impact of circRNA-mediated autophagy on tumor therapeutic resistance: a novel perspective

Cancer therapeutic resistance remains a significant challenge in the pursuit of effective treatment strategies. Circular RNAs (circRNAs), a class of non-coding RNAs, have recently emerged as key regulators of various biological processes, including cancer progression and drug resistance. This review highlights the emerging role of circRNAs-mediated autophagy in cancer therapeutic resistance, a cellular process that plays a dual role in cancer by promoting both cell survival and death. Increasing evidence suggests that circRNAs can modulate autophagy pathways, thereby influencing the response of cancer cells to therapeutic agents. In this context, the intricate interplay between circRNAs, autophagy, and therapeutic resistance is explored. Various mechanisms are discussed through which circRNAs can impact autophagy, including direct interactions with autophagy-related genes, modulation of signaling pathways, and cross-talk with other non-coding RNAs. Furthermore, the review delves into specific examples of how circRNA-mediated autophagy regulation can contribute to resistance against chemotherapy and radiotherapy. Understanding these intricate molecular interactions provides valuable insights into potential strategies for overcoming therapeutic resistance in cancer. Exploiting circRNAs as therapeutic targets or utilizing them as diagnostic and predictive biomarkers opens new avenues for developing personalized treatment approaches. In summary, this review underscores the importance of circRNA-mediated autophagy in cancer therapeutic resistance and proposes future directions for research in this exciting and rapidly evolving field.

Role of circular RNAs in lung cancer

Lung cancer remains a global public health concern with significant research focus on developing better diagnosis/prognosis biomarkers and therapeutical targets. Circular RNAs (circRNAs) are a type of single-stranded RNA molecules that covalently closed and have ubiquitous expression. These molecules have been implicated in a variety of disease mechanisms, including lung cancer, as they exhibit oncogenic or tumor suppressor characteristics. Recent research has shown an important role that circRNAs play at different stages of lung cancer, particularly in lung adenocarcinoma. In this review, we summarize the latest research on circRNAs and their roles within lung cancer diagnosis, as well as on disease mechanisms. We also discuss the knowledge gaps on these topics and possible future research directions.

Analysis of Potential Circular RNAs in Regulating Imatinib Resistance of Gastrointestinal Stromal Tumor

INTRODUCTION

Recent studies have found that circular RNA is an abundant RNA species that belongs to part of the competing endogenous RNA network (ceRNA), which was proven to play an important role in the development, diagnosis and progress of diseases. However, the function of circRNAs in imatinib resistance in Gastrointestinal stromal tumor (GIST) are poorly understood so for. The present study aimed to screen and predict the potential circRNAs in imatinib resistance of GIST using microarray analysis.

METHODS

We determined the expression of circular RNAs in paired normal gastric tissues (N), primary GIST (gastrointestinal stromal tumor) tissues (YC) and imatinib mesylate secondary resistance GIST tissues (C) with microarray and predicted 8677 dysregulated circular RNAs.

RESULTS

Compared with the YC group, we identified 15 circRNAs that were up-regulated and 8 circRNAs that were down-regulated in the C group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that these host linear transcripts that differentially express circular RNAs are involved in many key biological pathways, predicting the potential tumor-genesis and drug resistance mechanismrelated to HIF-1 pathway, later we draw the cirRNA-miRNA-mRNA network involved in the HIF-1 pathway and found several dysregulated circRNAs and the relationship between circRNA-miRNAs-mRNA, such as circRNA_06551, circRNA_14668, circRNA_04497, circRNA_08683, circRNA_09923(Green, down-regulation) and circRNA_23636, circRNA_15734 (Red, up-regulation).

CONCLUSION

Taken together, we identified a panel of dysregulated circRNAs that may be potential biomarkers even therapy relevant to the GIST, especially imatinib secondary resistance GIST.

The role of CDR1as/ciRS-7 in cardio-cerebrovascular diseases

Cerebellar degeneration-related protein 1 antisense RNA (CDR1as), also known as ciRS-7, is a circular natural antisense transcript of CDR1. It is a widely studied and powerful representative of circular RNAs. Based on its widely reported role in cancer, CDR1as is considered one of the most promising biomarkers for diagnosing and treating tumours. However, some recent studies have extensively focused on its regulatory role in cardio-cerebrovascular diseases instead of in tumours. Studies have shown that CDR1as plays a unique role in the occurrence of cardio-cerebrovascular diseases; thus, it may be a potential target for preventing and treating cardio-cerebrovascular diseases. Furthermore, CDR1as has also been found to be related to signal transduction pathways related to inflammatory response, oxidative stress, etc., which may reveal its potential mechanism in cardio-cerebrovascular diseases. However, there is no literature to summarize the role and possible mechanism of CDR1as in cardio-cerebrovascular diseases. Therefore, in the present review, we have comprehensively summarised the latest progress in the biological characteristics, development processes, regulatory mechanisms, and roles of CDR1as in cardio-cerebrovascular diseases, aiming to provide a reference and guidance for future studies.

Circ_0010235 confers cisplatin resistance in lung cancer by upregulating E2F7 through absorbing miR-379-5p

BACKGROUND

Cisplatin (DDP) treatment is one of the most predominant chemotherapeutic strategies for lung cancer patients. Circular RNAs (circRNAs) have been revealed to participate in the chemoresistance in lung cancer. Hence, the role and mechanism of circ_0010235 in cisplatin resistance in lung cancer was investigated.

METHODS

Expression levels of circ_0010235, microRNA (miR)-379-5p and E2F transcription factor 7 (E2F7) were analyzed using quantitative reverse transcription PCR (qRT-PCR) and western blot. Cell DDP sensitivity, proliferation, apoptosis, invasion, and migration were detected by cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, flow cytometry and western blot, respectively. The binding interaction was verified using dual-luciferase reporter assay. A murine xenograft model was established to investigate effects in vivo.

RESULTS

Circ_0010235 was highly expressed in DDP-resistant lung cancer tissues and cells. Knockdown of circ_0010235 elevated DDP sensitivity, constrained proliferation, invasion and migration as well as fostered apoptosis in DDP-resistant lung cancer cells. Moreover, circ_0010235 silencing boosted DDP sensitivity and impeded tumor growth in lung cancer in vivo. Mechanistically, circ_0010235 acted as a sponge for miR-379-5p to elevate the expression of its target E2F7. Rescue experiments showed that miR-379-5p inhibition attenuated circ_0010235 knockdown-evoked reduction on DDP resistance of DDP-resistant cancer cells. In addition, miR-379-5p re-expression elevated DDP sensitivity and suppressed the malignant phenotype of DDP-resistant lung cancer cells through miR-379-5p.

CONCLUSION

Circ_0010235 knockdown reduced DDP resistance and tumor growth via miR-379-5p/ E2F7 axis in lung cancer, suggesting an effective therapeutic target for lung cancer patients.

CircRBM33 promotes migration, invasion and mediates osimertinib resistance in non-small cell lung cancer cell line

Background

It has been shown that circular RNAs (circRNAs) are involved in the pathogenesis of non-small cell lung cancer (NSCLC). However, the molecular mechanisms of circRNAs in tumor malignant progression and tyrosine kinase inhibitors (TKI) resistance remain undefined. Hereby, we explored the mechanisms by which circRBM33 promotes NSCLC progression and epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) resistance.

Methods

Transcriptome sequencing (RNA-seq) was carried out to obtain the circRBM33 we investigated. Quantitative reverse transcriptase-polymerase chain reaction was performed to detect the expression of circRBM33. Cell counting kit-8 assay was performed to detect cell proliferation as well as flow cytometry to detect cell cycle and apoptosis. Transwell assay was performed to detect cell migration and invasion. In vivo tumourigenesis assays were performed to further validate the function of circRBM33. The transcriptome was sequenced after RNA-pulldown and knockdown of cirRBM33 to identify the proteins bound by cirRBM33 and the downstream mechanisms involved in the regulation of cirRBM33.

Results

The sequencing results revealed that cirRBM33 was highly expressed in the cell line of osimertinib resistant H1975. In vitro functional validation demonstrated that knockdown of circRBM33 inhibited H1975 proliferation, migration and invasion, changed cell cycle and promoted apoptosis. In vivo, knockdown of circRBM33 inhibited tumour growth. Mass spectrometry results and sequencing analysis of knockdown circRBM33 suggest that circRBM33 may mediate resistance to osimertinib in H1975-OR cells through regulate the DNMT1/interleukin-6 (IL-6) axis.

Conclusions

CircRBM33 is upregulated in NSCLC and that knockdown of circRBM33 inhibits the progression of NSCLC. CircRBM33 may combine with DNMT1, and regulate the resistance of H1975 osimertinib-resistant cells to osimertinib that mediated by IL6. CircRBM33 is a promising diagnostic and prognostic marker to provide effective treatment strategies for NSCLC patients.

TGF-β signaling promotes cervical cancer metastasis via CDR1as

BACKGROUND

Due to the lack of effective treatment, metastasis is the main cause of cancer related deaths. TGF-β pathway has been reported related to cervical cancer metastasis. However, mechanism is still unclear.

METHODS

After agonist of TGF-β treatment, RNA sequencing revealed the expression profiles of circRNA in cervical cancer. In situ hybridization was used to analysis relationship between CDR1as and prognosis. Real-time PCR, Western blot, RNA interference, Transwell assay, Wound healing assay, RNA pulldown assay and RIP assays were performed in vitro. And in vivo cervical cancer model (including foot pad model and subcutaneous tumor formation) was also performed.

RESULTS

CDR1as was found upregulated obviously following TGF-β activation. In situ hybridization showed CDR1as was positively correlated with lymph node metastasis and shortened survival length. Simultaneously, overexpression of CDR1as promoted cervical cancer metastasis in vitro and in vivo. It was also found that CDR1as could facilitate the orchestration of IGF2BP1 on the mRNA of SLUG and stabilize it from degradation. Silencing IGF2BP1 hampers CDR1as related metastasis in cervical cancer. Additionally, effective CDR1as has been proven to activate TGF-β signaling factors known to promote EMT, including P-Smad2 and P-Smad3.

CONCLUSIONS

Our study proved TGF-β signaling may promote cervical cancer metastasis via CDR1as.

Circular RNAs in chemotherapy resistance of lung cancer and their potential therapeutic application

Lung cancer is one of the high malignancy-related incidence and mortality worldwide, accounting for about 13% of total cancer diagnoses. Currently, the use of anti-cancer agents is still the main therapeutic method for lung cancer. However, cancer cells will gradually show resistance to these drugs with the progress of treatment. And the molecular mechanisms underlying chemotherapy agents resistance remain unclear. circRNAs are newly identified noncoding RNAs molecules with covalently closed circular structures. Previous studies have shown that circRNAs are associated with tumorigenesis and progression of various cancers, including lung cancer. Recently, growing reports have suggested that circRNAs could contribute to drug resistance of lung cancer cell through different mechanisms. Therefore, in this review, we summarized the functions and underlying mechanisms of circRNAs in regulating chemoresistance of lung cancer and discussed their potential applications for diagnosis, prognosis, and treatment of lung cancer.

The Tumorigenic Role of Circular RNA-MicroRNA Axis in Cancer

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

Circ_0048856 competes with ABCC1 for miR-193a-5p/miR-98-5p binding sites to promote the cisplatin resistance and tumorigenesis in lung cancer

Although cisplatin (DDP)-based therapy is the most predominant chemotherapeutic strategy used for lung cancer, drug resistance usually occurs after several cycle use of it. Circular RNAs (circRNAs) are found to be involved in the chemoresistance in lung cancer. Hence, this study aimed to clarify the role and mechanism of circ_0048856 in lung cancer tumorigenesis and DDP resistance. The levels of circ_0048856, miR-193a-5p, miR-98-5p and ABCC1 (ATP Binding Cassette Subfamily C Member 1) were determined by qRT-PCR and western blotting. In vitro assays were conducted by cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, flow cytometry and transwell assay, respectively. The binding interaction was verified using dual-luciferase reporter assay and RIP assay. In vivo experiment was performed by the establishment of murine xenograft model. Circ_0048856 was highly expressed in DDP-resistant lung cancer tissues and cells. Functionally, circ_0048856 silencing re-sensitized DDP-resistant lung cancer cells to DDP, as well as suppressed cell growth and invasion in lung cancer in vitro and in vivo. Mechanistically, circ_0048856 acted as the sponge for miR-193a-5p or miR-98-5p, which targeted ABCC1. Furthermore, rescue experiments showed that inhibition of miR-193a-5p or miR-98-5p reversed the effects of circ_0048856 knockdown on lung cancer cells. Besides that, overexpression of miR-193a-5p or miR-98-5p suppressed cell tumorigenesis and reduced DDP resistance in lung cancer, which were attenuated by ABCC1 up-regulation. Circ_0048856 knockdown suppressed tumor growth and reduced DDP resistance in lung cancer by miR-193a-5p/ABCC1 or miR-98-5p/ABCC1 axis, indicating a novel strategy for efficient application of DDP in lung cancer.

Circular RNA circPRDX3 mediates neuronal survival apoptosis in ischemic stroke by targeting miR-641 and NPR3

OBJECTIVE

circPRDX3 is a circular RNA (circRNA) that has received little attention yet. The purpose of this research is to elucidate circPRDX3 expression pattern and its underlying network in ischemic stroke (IS).

METHODS

Oxygen-glucose deprivation on/reoxygenation (OGD/R) and mice model of middle cerebral artery occlusion (MCAO) were used to generate IS model in N2a cells or mice, respectively. Expression levels of circPRDX3, miR-641, Natriuretic Peptide Receptor 3 (NPR3), and members of the mitogen-activated protein kinases (MAPK) pathway were determined using real-time quantitative PCR (qRT-PCR) and western blot. Cell viability was assessed by CCK-8 assay and apoptosis was evaluated using TUNEL staining and flow cytometry. Molecule-molecule interactions were verified by dual luciferase and RNA immunoprecipitation (RIP) assays. The infarcted area was depicted by Triphenyl tetrazolium chloride (TTC) staining and the level of neurological function was measured using National Institute of Health stroke scale (NIHSS).

RESULTS

CircPRDX3 and NPR3 were shown to be considerably downregulated in IS samples, as well as OGD/R cells or MCAO mice, while miR-641 was found to be significantly upregulated. A circPRDX3/miR-641/NPR3 mechinary was verified using luciferase and RIP assays. Overexpression of circPRDX3 dramatically reduced miR-641 expression and increased NPR3 expression, boosting cell survival and lowering apoptosis in an OGD/R model, either with inactivated MAPK signaling pathways. Moreover, overexpression of circPRDX3 lowered infarct volume and enhanced neurobehavioral outcomes in mice after MCAO, and these protective effects were dramatically abrogated by depletion of NPR3.

CONCLUSION

Altogether, circPRDX3 inhibited the development of IS by sponging miR-641, hence increasing NPR3 expression and inactivating MAPK pathway. These results may aid in the search of potential therapy targets for IS.

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.

The emerging role of circular RNAs in drug resistance of non-small cell lung cancer

Due to the characteristics of aggressiveness and high risk of postoperative recurrence, non-small cell lung cancer (NSCLC) is a serious hazard to human health, accounting for 85% of all lung cancer cases. Drug therapies, including chemotherapy, targeted therapy and immunotherapy, are effective treatments for NSCLC in clinics. However, most patients ultimately develop drug resistance, which is also the leading cause of treatment failure in cancer. To date, the mechanisms of drug resistance have yet to be fully elucidated, thus original strategies are developed to overcome this issue. Emerging studies have illustrated that circular RNAs (circRNAs) participate in the generation of therapeutic resistance in NSCLC. CircRNAs mediate the modulations of immune cells, cytokines, autophagy, ferroptosis and metabolism in the tumor microenvironment (TME), which play essential roles in the generation of drug resistance of NSCLC. More importantly, circRNAs function as miRNAs sponges to affect specific signaling pathways, directly leading to the generation of drug resistance. Consequently, this review highlights the mechanisms underlying the relationship between circRNAs and drug resistance in NSCLC. Additionally, several therapeutic drugs associated with circRNAs are summarized, aiming to provide references for circRNAs serving as potential therapeutic targets in overcoming drug resistance in NSCLC.

Identification of a dysregulated CircRNA-associated gene signature for predicting prognosis, immune landscape, and drug candidates in bladder cancer

Increasing evidences have demonstrated that circular RNA (circRNAs) plays a an essential regulatory role in initiation, progression and immunotherapy resistance of various cancers. However, circRNAs have rarely been studied in bladder cancer (BCa). The purpose of this research is to explore new circRNAs and their potential mechanisms in BCa. A novel ceRNA-regulated network, including 87 differentially expressed circRNAs (DE-circRNAs), 126 DE-miRNAs, and 217 DE-mRNAs was constructed to better understanding the biological processes using Cytoscape 3.7.1 based on our previously high-throughput circRNA sequencing and five GEO datasets. Subsequently, five randomly selected circRNAs (upregulated circ_0001681; downregulated circ_0000643, circ_0001798, circ_0006117 and circ_0067900) in 20 pairs of BCa and paracancerous tissues were confirmed using qRT-PCR. Functional analysis results determined that 772 GO functions and 32 KEGG pathways were enriched in the ceRNA network. Ten genes (PFKFB4, EDNRA, GSN, GAS1, PAPPA, DTL, TGFBI, PRSS8, RGS1 and TCF4) were selected for signature construction among the ceRNA network. The Human Protein Atlas (HPA) expression of these genes were consistent with the above sequencing data. Notably, the model was validated in multiple external datasets (GSE13507, GSE31684, GSE48075, IMvigor210 and GSE32894). The immune-infiltration was evaluated by 7 published algorithms (i.e., TIMER, CIBERSORT, CIBERSORT-ABS, QUANTISEQ, MCPCOUNTER, XCELL and EPIC). Next, Correlations between riskscore or risk groups and clinicopathological data, overall survival, recognized immunoregulatory cells or common chemotherapeutic agents of BCa patients were performed using wilcox rank test, chi-square test, cox regression and spearman’s correlation analysis; and, these results are significant. According to R package “GSVA” and “clusterProfiler”, the most significantly enriched HALLMARK and KEGG pathway was separately the ‘Epithelial Mesenchymal Transition’ and ‘Ecm Receptor Interaction’ in the high- vs. low-risk group. Additionally, the functional experiments in vitro also revealed that the overexpression of has_circ_0067900 significantly impaired the proliferation, migration, and invasion capacities of BCa cells. Collectively, the results of the current study provide a novel landscape of circRNA-associated ceRNA-regulated network in BCa. The ceRNA-associated gene model which was constructed presented a high predictive performance for the prognosis, immunotherapeutic responsiveness, and chemotherapeutic sensitivity of BCa. And, has_circ_0067900 was originally proposed as tumor suppressor for patients with BCa.

CircRNA circ_0005273 contributes to the cisplatin resistance of cervical cancer cells by sponging miR-133b

Circular RNAs (circRNAs) have been found to play important roles in drug resistance of human neoplasms. The aim of this study was to explore the effect of circ_0005273 on cisplatin (DDP) resistance of cervical cancer (CC) cells and identify its underlying mechanism. The quantitative real-time polymerase chain reaction (qRT-PCR) was performed to analyse circ_0005273 and miR-133b expressions, and cell counting kit-8 (CCK-8), Hoechst 33258 staining and caspase-3 activity analysis were performed to evaluate cell proliferation and apoptosis. Luciferase reporter, RNA binding protein immunoprecipitation (RIP) and RNA pull down assays were applied to explore the interaction between circ_0005273 and miR-133b. Our research showed that circ_0005273 and miR-133b expressions were upregulated and downregulated in DDP-resistant CC cancer tissues and cell lines, respectively. Both of circ_0005273 and miR-133b levels were correlated with FIGO stage, DDP status and overall survival rates. Knockdown of circ_0005273 enhanced the sensitivity of DDP-resistant CC cells to DDP by inhibiting cell proliferation and promoting cell apoptosis. Furthermore, circ_0005273 acts as a competing endogenous RNA to modulate miR-133b expression. Downregulation of miR-133b partly reversed the DDP sensitivity of circ_0005273 knockdown in DDP-resistant CC cells. In summary, our study elucidated the role of circ_0005273/miR-133b axis in DDP resistance of CC cells, which might be a potential therapeutic target for DDP-resistant CC patients. Impact StatementWhat is already known on this subject? The detailed regulatory mechanisms underlying DDP chemoresistance are still unclear. Recently, literatures reported that circ_0005273 exerts a regulatory role in the tumorigenesis and progression of human cancers including thyroid carcinoma, pancreatic carcinoma, colorectal carcinoma and breast carcinoma.What do the results of this study add? Circ_0005273 contributes to the DDP resistance of CC cells via sponging miR-133b.What are the implications of these findings for clinical practice and/or further research? The results help to reverse DDP chemoresistance, and the circ_0005273/miR-133b axis might be a potential therapeutic target for DDP-resistant CC patients.

Non-coding RNA in cancer drug resistance: Underlying mechanisms and clinical applications

Cancer is one of the most frequently diagnosed malignant diseases worldwide, posing a serious, long-term threat to patients’ health and life. Systemic chemotherapy remains the first-line therapeutic approach for recurrent or metastatic cancer patients after surgery, with the potential to effectively extend patient survival. However, the development of drug resistance seriously limits the clinical efficiency of chemotherapy and ultimately results in treatment failure and patient death. A large number of studies have shown that non-coding RNAs (ncRNAs), particularly microRNAs, long non-coding RNAs, and circular RNAs, are widely involved in the regulation of cancer drug resistance. Their dysregulation contributes to the development of cancer drug resistance by modulating the expression of specific target genes involved in cellular apoptosis, autophagy, drug efflux, epithelial-to-mesenchymal transition (EMT), and cancer stem cells (CSCs). Moreover, some ncRNAs also possess great potential as efficient, specific biomarkers in diagnosis and prognosis as well as therapeutic targets in cancer patients. In this review, we summarize the recent findings on the emerging role and underlying mechanisms of ncRNAs involved in cancer drug resistance and focus on their clinical applications as biomarkers and therapeutic targets in cancer treatment. This information will be of great benefit to early diagnosis and prognostic assessments of cancer as well as the development of ncRNA-based therapeutic strategies for cancer patients.

Mutual regulation between N6-methyladenosine (m6A) modification and circular RNAs in cancer: impacts on therapeutic resistance

The resistance of tumor cells to therapy severely impairs the efficacy of treatment, leading to recurrence and metastasis of various cancers. Clarifying the underlying mechanisms of therapeutic resistance may provide new strategies for overcoming cancer resistance. N6-methyladenosine (m6A) is the most prevalent RNA modification in eukaryotes, and is involved in the regulation of RNA splicing, translation, transport, degradation, stability and processing, thus affecting several physiological processes and cancer progression. As a novel type of multifunctional non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been demonstrated to play vital roles in anticancer therapy. Currently, accumulating studies have revealed the mutual regulation of m6A modification and circRNAs, and their interaction can further influence the sensitivity of cancer treatment. In this review, we mainly summarized the recent advances of m6A modification and circRNAs in the modulation of cancer therapeutic resistance, as well as their interplay and potential mechanisms, providing promising insights and future directions in reversal of therapeutic resistance in cancer.

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.

CircRNAs in lung cancer- role and clinical application

Lung cancer holds the highest mortality rate among malignancies worldwide. Nevertheless, the potential molecular mechanisms of its tumorigenesis and evolution remain obscure. Circular RNAs (circRNAs), a broad category of covalently closed molecules, follow a malignancy-restricted expression pattern. Leading-edge studies have demonstrated the clinical application prospects of circRNAs in lung cancer. Herein, this review elucidates the biogenesis, biological functions, and pathophysiology of circRNAs. Furthermore, we underscore the forefront of the diagnostic, prognostic, and therapeutic potential of circRNAs in lung cancer as well as discuss the bottleneck that needs to be overcome to translate the basic advances of circRNAs into clinical practice.

Aberrant Nuclear Export of circNCOR1 Underlies SMAD7-Mediated Lymph Node Metastasis of Bladder Cancer

Circular RNAs (circRNA) containing retained introns are normally sequestered in the nucleus. Dysregulation of cellular homeostasis can drive their nuclear export, which may be involved in cancer metastasis. However, the mechanism underlying circRNA nuclear export and its role in lymph node (LN) metastasis of bladder cancer remain unclear. Here, we identify an intron-retained circRNA, circNCOR1, that is significantly downregulated in LN metastatic bladder cancer and is negatively associated with poor prognosis of patients. Overexpression of circNCOR1 inhibited lymphangiogenesis and LN metastasis of bladder cancer in vitro and in vivo. Nuclear circNCOR1 epigenetically promoted SMAD7 transcription by increasing heterogeneous nuclear ribonucleoprotein L (hnRNPL)-induced H3K9 acetylation in the SMAD7 promoter, leading to inhibition of the TGFβ-SMAD signaling pathway. Nuclear retention of circNCOR1 was regulated by small ubiquitin-like modifier (SUMO)ylation of DDX39B, an essential regulatory factor responsible for circRNA nuclear-cytoplasmic transport. Reduced SUMO2 binding to DDX39B markedly increased circNCOR1 retention in the nucleus to suppress bladder cancer LN metastasis. By contrast, SUMOylated DDX39B activated nuclear export of circNCOR1, impairing the suppressive role of circNCOR1 on TGFβ-SMAD cascade activation and bladder cancer LN metastasis. In patient-derived xenograft (PDX) models, overexpression of circNCOR1 and inhibition of TGFβ signaling significantly repressed tumor growth and LN metastasis. This study highlights SUMOylation-induced nuclear export of circNCOR1 as a key event regulating TGFβ-SMAD signaling and bladder cancer lymphangiogenesis, thus supporting circNCOR1 as a novel therapeutic agent for patients with LN metastatic bladder cancer.

SIGNIFICANCE

This study identifies the novel intron-retained circNCOR1 and elucidates a SUMOylation-mediated DDX39B-circNCOR1-SMAD7 axis that regulates lymph node metastasis of bladder cancer.

Circ_CDR1as: A circular RNA with roles in the carcinogenesis

Circular RNAs are a group of ancient but recently appreciated transcripts that affect carcinogenesis. An example of cancer-related circular RNAs is circ_CDR1as. It is mostly regarded as an oncogenic circular RNA, yet in bladder cancer and glioma it has the opposite effect. In gastric and ovarian cancer, both roles have been reported for this circular RNA. Circ_CDR1as has regulatory effects on miR-1270/AFP, miR-1287/Raf1, miR-7-5p/KLF4, miR-641/HOXA9, miR-219a-5p/SOX5, miR-7/HOXB13 and miR-876-5p/MAGE-A molecular axes. miR-7 is the most appreciated interacting miRNA with circ_CDR1as, since its interaction with circ_CDR1as has been validated in liver cancer, lung cancer, colorectal cancer, esophageal carcinoma, gastric cancer, pancreatic cancer, thyroid cancer, oral squamous cell carcinoma, nasopharyngeal carcinoma and osteosarcoma. The present article aims at summarization of the role of circ_CDR1as in neoplasms and its application as a biomarker in human cancers.

Emerging roles of circular RNAs in stem cells

Circular RNAs (circRNAs) are a novel class of noncoding RNAs that widely exist in eukaryotes. As a new focus in the field of molecular regulation, circRNAs have attracted much attention in recent years. Previous studies have confirmed that circRNAs are associated with many physiological and pathological processes. CircRNAs also participate in the regulation of stem cells. Stem cells have the properties of self-renewal and differentiation, which make stem cell therapy popular. CircRNAs may serve as new targets in stem cell therapy due to their regulation in stem cells. However, the underlying relationships between circRNAs and stem cells are still being explored. In this review, we briefly summarize the effects of circRNAs on stem cells, in the context of biological activities, aging and apoptosis, and aberrant changes. Moreover, we also examine the biological roles of stem cell-derived exosomal circRNAs. We believe our review will provide insights into the effects of circRNAs on stem cells.

Contribution of MicroRNAs in Chemoresistance to Cisplatin in the Top Five Deadliest Cancer: An Updated Review

Cisplatin (DDP) is a well-known anticancer drug used for the treatment of numerous human cancers in solid organs, including bladder, breast, cervical, head and neck squamous cell, ovarian, among others. Its most important mode of action is the DNA-platinum adducts formation, inducing DNA damage response, silencing or activating several genes to induce apoptosis; these mechanisms result in genetics and epigenetics modifications. The ability of DDP to induce tumor cell death is often challenged by the presence of anti-apoptotic regulators, leading to chemoresistance, wherein many patients who have or will develop DDP-resistance. Cancer cells resist the apoptotic effect of chemotherapy, being a problem that severely restricts the successful results of treatment for many human cancers. In the last 30 years, researchers have discovered there are several types of RNAs, and among the most important are non-coding RNAs (ncRNAs), a class of RNAs that are not involved in protein production, but they are implicated in gene expression regulation, and representing the 98% of the human genome non-translated. Some ncRNAs of great interest are long ncRNAs, circular RNAs, and microRNAs (miRs). Accumulating studies reveal that aberrant miRs expression can affect the development of chemotherapy drug resistance, by modulating the expression of relevant target proteins. Thus, identifying molecular mechanisms underlying chemoresistance development is fundamental for setting strategies to improve the prognosis of patients with different types of cancer. Therefore, this review aimed to identify and summarize miRs that modulate chemoresistance in DDP-resistant in the top five deadliest cancer, both in vitro and in vivo human models.

Mechanism of RNA circHIPK3 Involved in Resistance of Lung Cancer Cells to Gefitinib

To study the mechanism of circular ribonucleic acid (RNA) circHIPK3 involved in the resistance of lung cancer cells to gefitinib, 110 patients with lung cancer were recruited as the research objects, and the tumor tissue and para-cancerous tissue of each patient's surgical specimens were collected and paraffinized to detect the expression of circHIPK3 in different tissues. Gefitinib drug-resistant cell line of lung cancer was constructed with gefitinib to detect cell apoptosis under different conditions. As a result, the relative expression of circHIPK3 in patients with tumor diameter no less than 3 cm was dramatically inferior to that in patients with tumor diameter less than 3 cm (P < 0.05). The relative expression of circHIPK3 in patients with TNM stage II/III was dramatically inferior to that in patients with tumor, node, and metastasis (TNM) stage I (P < 0.05). Expression of circHIPK3 in patients with lymph node metastasis was dramatically inferior to that in patients without lymph node metastasis (P < 0.05). Of the lung cancer tissues of patients with different TNM stages, only six patients had high expression, and the remaining 104 patients had low expression. Moreover, electrophoresis revealed that circHIPK3 can only be amplified in cDNA, but not in gDNA. Gefitinib-mediated apoptosis rate of lung cancer drug-resistant cell lines decreased notably. In summary, the circular RNA circHIPK3 may have a notably low expression in lung cancer tissues, whose low expression had a certain enhancement effect on the drug resistance of lung adenocarcinoma cells to gefitinib.

hsa_circ_0077837 Alleviated the Malignancy of Non-Small Cell Lung Cancer by Regulating the miR-1178-3p/APITD1 Axis

Objective

circRNAs were a group of the most promising molecular biomarkers for clinical prognosis and diagnosis of non-small cell lung cancer (NSCLC). It was a pity that academic circle still struggled to figure out how circRNAs acted on NSCLC. This article aimed to study the function and mechanism of hsa_circ_0077837 in NSCLC progression.

Methods

Cell viability was measured via CCK-8, while apoptosis was evaluated with flow cytometry. The transwell assay and scratch test were used to detect invasion and migration, respectively. The dual-luciferase reporter gene assay verified the regulatory effect of miR-1178-3p on hsa_circ_0077837 and miR-1178-3p on apoptosis-inducing, TAF9-like domain 1 (APITD1). The TUNEL assay and immunohistochemistry were used to assess cells apoptosis and proliferation in lung tumor tissues in mice.

Results

Hsa_circ_0077837 and APITD1 expression were suppressed in NSCLC tissues and cells, and miR-1178-3p level was promoted. High amount of hsa_circ_0077837 intensely prevented cell proliferation, migration, and invasion, promoted cell apoptosis in vitro, and delayed tumor growth in mice. Further analysis indicated that hsa_circ_0077837 acted as a miR-1178-3p sponge to stabilize APITD1, the target of miR-1178-3p. Mechanistically, we discovered that hsa_circ_0077837 could prevent proliferation, viability, migration, and invasion of NSCLC cells through stimulating the miR-1178-3p/APITD1 pathway.

Conclusion

Collectively, our findings validated that hsa_circ_0077837 served as a miR-1178-3p sponge by targeting APITD1 that alleviated NSCLC progression.

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.

Circular RNA CDR1as Alleviates Cisplatin-Based Chemoresistance by Suppressing MiR-1299 in Ovarian Cancer

Cisplatin (CDDP) chemoresistance seriously affects the prognosis and survival of patients with ovarian cancer (OC). Previous research has shown that circular RNA CDR1as is biologically associated with a large number of cancers. However, the molecular mechanism underlying the role of CDR1as in CDDP chemoresistance in OC remains unclear. Here, we investigated the mechanism of CDR1as in CDDP-resistant OC. First, we employed bioinformatics analysis and quantitative real-time PCR (qRT-PCR) to determine the expression of CDR1as and related RNAs in CDDP-sensitive and -resistant OC tissues and cells. Then, functional experiments were used to determine cell proliferation, invasion, migration, and apoptosis in CDDP chemoresistance and parent OC cells in vitro. The effect of CDR1as in CDDP chemoresistance OC progression was tested in nude mice in vivo. Moreover, dual-luciferase assays and RNA immunoprecipitation (RIP) were performed to confirm the interactions of CDR1as and related RNAs. Finally, we used Western blotting to determine protein expression levels. Our findings interpret the underlying mechanisms of the CDR1as/miR-1299/PPP1R12B axis and shed light on the clinical applications for CDDP-chemoresistant OC.

Circular RNAs and Drug Resistance in Genitourinary Cancers: A Literature Review

In recent years, systematic treatment has made great progress in genitourinary tumors. However, some patients develop resistance to the treatments, resulting in an increase in mortality. Circular RNAs (circRNAs) form a class of non-coding RNAs with high stability and significant clinical relevance. Accumulating evidence indicates that circRNAs play a vital role in cancer development and tumor chemotherapy resistance. This review summarizes the molecular and cellular mechanisms of drug resistance mediated by circRNAs to common drugs used in the treatment of genitourinary tumors. Several circRNAs were identified to regulate the responsiveness to systemic treatments in genitourinary tumors, including chemotherapies such as cisplatin and targeted therapies such as enzalutamide. Canonically, cicrRNAs participate in the competing endogenous RNA (ceRNA) network, or in some cases directly interact with proteins, regulate downstream pathways, and even some circRNAs have the potential to produce proteins or polypeptides. Several cellular mechanisms were involved in circRNA-dependent drug resistance, including autophagy, cancer stem cells, epithelial-mesenchymal transition, and exosomes. The potential clinical prospect of circRNAs in regulating tumor drug resistance was also discussed.

Circ-SNAP47 (hsa_circ_0016760) and miR-625-5p are regulators of WEE1 in regulation of chemoresistance, growth and invasion of DDP-tolerant NSCLC cells via ceRNA pathway

Circular RNA-synaptosome associated protein 47 (circ-SNAP47; Hsa_circ_0016760) is oncogenic in non-small-cell lung cancer (NSCLC); however, its role is undescribed in cis-diamminedichloroplatinum II (DDP) resistance. We attempted to investigate its expression, role and mechanism in DDP-tolerant NSCLC. As a result, circ-SNAP47 expression was upregulated in human DDP-tolerant NSCLC tissues and cells, accompanied with WEE1 G2 checkpoint kinase (WEE1) upregulation and microRNA (miR)-625-5p downregulation. Functionally, interfering circ-SNAP47 and/or restoring miR-625-5p curbed the 50% inhibitory concentration of DDP, colony formation, cell proliferation and invasion, accompanied with apoptotic rate promotion and depressions of multidrug resistance (MDR) markers MDR1 and MRP1, anti-apoptosis protein Bcl-2, and pro-invasion protein MMP9. Notably, circ-SNAP47 interference suppressed xenograft tumor growth of DDP-tolerant NSCLC cells by elevating miR-625-5p and descending WEE1. Mechanistically, circ-SNAP47 directly targeted miR-625-5p, and miR-625-5p further targeted WEE1. Therefore, circ-SNAP47-miR-625-5p-WEE1 axis might participate in chemoresistance and progression of DDP-tolerant NSCLC.

CircularRNA circ_0071269 knockdown protects against from diabetic cardiomyopathy injury by microRNA-145/gasdermin A axis

Circular RNAs (circRNAs) are involved in the development and progression of diabetic cardiomyopathy (DCM). However, the specific function and underlying mechanism of circ_0071269 in DCM remains unclear. In our study, mRNA and miRNA expression was detected by real-time quantitative PCR (qRT-PCR). RNase R and actinomycin D treatment were applied to test the characteristics of circ_0071269. Cell Counting Kit-8 (CCK-8) assay, lactate dehydrogenase (LDH) and enzyme-linked immunosorbent assay (ELISA) kits were performed to determine the cell viability, cell LDH content and interleukin (IL)-1β and IL-18 levels, respectively. Cell death rate was determined by Flow cytometry, and Western blotting was for the protein expression levels. In addition, luciferase reporter and RNA pull-down assays were performed to confirm the binding relationship between miR-145 and circ_0071269 or gasdermin A (GSDMA). Echocardiography, Hematoxylin and Eosin (HE) Staining, and Immunohistochemical (IHC) Staining were performed to evaluate myocardial damage in vivo. We found that circ_0071269 was significantly overexpressed in H9c2 cells upon treatment with high glucose. Knockdown of circ_0071269 promoted cell viability and inhibited the inflammatory response, cytotoxicity, and pyroptosis of H9c2 cells in vitro. Moreover, circ_0071269 sponges miR-145 to upregulate GSDMA. A miR-145 inhibitor antagonized the effects of circ_0071269 knockdown on the cellular functions of H9c2 cells, while the effects of miR-145 were abrogated by the overexpression of GSDMA. Meanwhile, knockdown of circ_0071269 attenuated cardiac dysfunction of DM mice. Hence, circ_0071269 may promote the development of DCM through the miR-145/GSDMA axis and thus provide a novel marker for the treatment of DCM.

circ_ZFR Is Linked to Paclitaxel Resistance in Cervical Cancer via miR-944 Sponging and IL-10 Upregulation

Objective

Cervical cancer (CC) has an elevated rate of invasion and death despite surgical treatment, radiotherapy, and chemotherapy. Several studies revealed that circRNAs have a key contribution to the resistance of drugs against different types of carcinomas. The goal of the existing study was to figure out what role circ_ZFR plays in paclitaxel (PTX) resistance in cervical cancer (CC) patients.

Materials and Methods

Herein, two types of CC cells (SiHa/PTX and Hela/PTX) were utilized. The levels of IL-10 mRNA, miR-944, and circ_ZFR were measured using qRT-PCR analyses. The CCK-8 assay was used to determine PTX resistance. The IL-10 expression was measured via the ELISA technique. The combination of miR-944 and circ_ZFR or IL-10 was validated using a dual-luciferase reporter (DLR) assay.

Results

The amount of circ_ZFR was increased in PTX-resistant CC cells and tissues. In PTX-resistant CC cells, knocking down circ_ZFR expression decreased PTX resistance. circ_ZFR knockdown significantly reduced IL-10 expression via sponging miR-944, increasing PTX sensitivity in PTX-resistant CC cells.

Conclusion

circ_ZFR knockdown has a considerable role in overwhelming CC-associated PTX resistance by modifying the axis of miR-944/IL-10 axis, suggesting that developing a circRNA target-based treatment could be considered prevent CC progression.

Circ-CUL2/microRNA-888-5p/RB1CC1 axis participates in cisplatin resistance in NSCLC via repressing cell advancement

Elevated evidences manifest that circular RNAs (circRNAs) are vital in human tumor advancement and chemotherapy resistance. The study was to explore the character of Circ-CUL2 in non-small cell lung cancer (NSCLC). Firstly, the expression of circ-CUL2, microRNA (miR)-888-5p and RB1CC1 was detected in human NSCLC tissues and cell lines by reverse transcription quantitative polymerase chain reaction or Western blot. Then, cell counting kit (CCK)-8, plate clone, Transwell assays, and flow cytometry were applied to separately detect the impacts of circ-CUL2 on proliferation, migration, invasion, apoptosis and cisplatin (DDP) resistance of A549/DDP cells. In this study, exploration of the biological function of Circ-CUL2 was via the Circ-CUL2/miR-888-5p/RB1CC1 axis. The results manifested circ-CUL2 and RB1CC1 were down-regulated in NSCLC tissues and cell lines, while miR-888-5p was up-regulated. Elevated Circ-CUL2 or refrained miR-888-5p repressed A549/DDP cell progression with depressive DDP resistance. Circ-CUL2 curbed miR-888-5p, which targeted RB1CC1. Restrained RB1CC1 turned around the impacts of Circ-CUL2 on the cells. All in all, Circ-CUL2 is anti-NSCLC via miR-888-5p/RB1CC1 axis, enhancing the sensitivity of A549/DDP cells to DDP. Hence, Circ-CUL2 is supposed to be a novel biomarker offering a brand-new strategy for NSCLC therapy.

Biomedical Applications of Non-Small Cell Lung Cancer Spheroids

Lung malignancies accounted for 11% of cancers worldwide in 2020 and remained the leading cause of cancer deaths. About 80% of lung cancers belong to non-small cell lung cancer (NSCLC), which is characterized by extremely high clonal and morphological heterogeneity of tumors and development of multidrug resistance. The improvement of current therapeutic strategies includes several directions. First, increasing knowledge in cancer biology results in better understanding of the mechanisms underlying malignant transformation, alterations in signal transduction, and crosstalk between cancer cells and the tumor microenvironment, including immune cells. In turn, it leads to the discovery of important molecular targets in cancer development, which might be affected pharmaceutically. The second direction focuses on the screening of novel drug candidates, synthetic or from natural sources. Finally, "personalization" of a therapeutic strategy enables maximal damage to the tumor of a patient. The personalization of treatment can be based on the drug screening performed using patient-derived tumor xenografts or in vitro patient-derived cell models. 3D multicellular cancer spheroids, generated from cancer cell lines or tumor-isolated cells, seem to be a helpful tool for the improvement of current NSCLC therapies. Spheroids are used as a tumor-mimicking in vitro model for screening of novel drugs, analysis of intercellular interactions, and oncogenic cell signaling. Moreover, several studies with tumor-derived spheroids suggest this model for the choice of "personalized" therapy. Here we aim to give an overview of the different applications of NSCLC spheroids and discuss the potential contribution of the spheroid model to the development of anticancer strategies.

Diverse Roles and Therapeutic Potentials of Circular RNAs in Urological Cancers

Circular RNAs (circRNAs) are a novel class of noncoding RNAs, which are mainly formed as a loop structure at the exons caused by noncanonical splicing; they are much more stable than linear transcripts; recent reports have suggested that the dysregulation of circRNAs is associated with the occurrence and development of diseases, especially various human malignancies. Emerging evidence demonstrated that a large number of circRNAs play a vital role in a series of biological processes such as tumor cell proliferation, migration, drug resistance, and immune escape. Additionally, circRNAs were also reported to be potential prognostic and diagnostic biomarkers in cancers. In this work, we systematically summarize the biogenesis and characteristics of circRNAs, paying special attention to potential mechanisms and clinical applications of circRNAs in urological cancers, which may help develop potential therapy targets for urological cancers in the future.

Cell Behavior of Non-Small Cell Lung Cancer Is at EGFR and MicroRNAs Hands

Lung cancer is a complex disease associated with gene mutations, particularly mutations of Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) and epidermal growth factor receptor (EGFR). Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the two major types of lung cancer. The former includes most lung cancers (85%) and are commonly associated with EGFR mutations. Several EGFR-tyrosine kinase inhibitors (EGFR-TKIs), including erlotinib, gefitinib, and osimertinib, are effective therapeutic agents in EGFR-mutated NSCLC. However, their effectiveness is limited by the development (acquired) or presence of intrinsic drug resistance. MicroRNAs (miRNAs) are key gene regulators that play a profound role in the development and outcomes for NSCLC via their role as oncogenes or oncosuppressors. The regulatory role of miRNA-dependent EGFR crosstalk depends on EGFR signaling pathway, including Rat Sarcoma/Rapidly Accelerated Fibrosarcoma/Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase 1/2 (Ras/Raf/MEK/ERK1/2), Signal Transducer and Activator of Transcription (STAT), Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-kB), phosphoinositide 3-kinase/protein kinase B (PI3K/AKT), Janus kinase 1 (JAK1), and growth factor receptor-bound protein 2 (GRB2). Dysregulated expression of miRNAs affects sensitivity to treatment with EGFR-TKIs. Thus, abnormalities in miRNA-dependent EGFR crosstalk can be used as diagnostic and prognostic markers, as well as therapeutic targets in NSCLC. In this review, we present an overview of miRNA-dependent EGFR expression regulation, which modulates the behavior and progression of NSCLC.

Circular RNA-CDR1as is involved in lung injury induced by long-term formaldehyde inhalation

OBJECTIVE

Formaldehyde (FA) is known to induce lung injury, but the underlying molecular mechanism remains largely unclear. CDR1as is an important member of the circular RNAs (circRNAs) family and functions as miRNA sponges with gene-regulatory potential. Our earlier circRNA microarray data showed CDR1as was highly expressed in lung tissue exposed to FA. However, the mechanism of circRNA-CDR1as mediates the FA-exposed lung injury is still unclear. This study aimed to explore the role of CDR1as in lung injury.

MATERIALS AND METHODS

In this study, FA was inhaled at doses of 0.5, 2.46, and 5 mg/m3, respectively. After exposure 8 weeks, lung histopathological examination, lung injury score, and IL-1β in bronchoalveolar lavage fluid (BALF) were determined. The expressions of CDR1as, rno-miR-7b and Atg7 were detected and the potential interaction of circRNA/miRNA/mRNA was predicted by bioinformatics analysis, including drawing circRNA/miRNA/mRNA interaction network, GO and KEGG analysis.

RESULTS

Our results indicated FA inhalation upregulated the expression of CDR1as in lung tissues in a dose-dependent manner while the expression of rno-miR-7b decreased and Atg7 increased. Moreover, the alteration of CDR1as was positively correlated with lung injury.

DISCUSSION AND CONCLUSIONS

CircRNA/miRNA/mRNA prediction further explained the possible effect mechanisms of CDR1as. These data implicated that CDR1as might be a critical regulator involved in lung injury induced by FA.

miR-381-3p attenuates doxorubicin resistance in human anaplastic thyroid carcinoma via targeting homeobox A9

Abnormal microRNA (miR) expression has frequently been reported to be implicated in cancer-related drug resistance. Herein, we planned to investigate whether miR-381-3p contributes to doxorubicin (DOX) resistance in anaplastic thyroid carcinoma (ATC). DOX-resistant ATC tissues and cell lines were prepared to detect miR-381-3p and homeobox A9 (HOXA9) expression. CCK8, transwell and TUNEL assays were performed to evaluate cell proliferation, migration and invasion, and apoptosis in in vitro experiments. HOXA9 expression is intensively expressed in ATC tissues compared with benign thyroid tissues. Compared with parental ATC cell lines, HOXA9 protein expression is significantly up-regulated in DOX-resistant SW1736 and CAL62 cells. The knockdown of HOXA9 leads to growth inhibition and apoptosis of DOX-resistant SW1736 and CAL62 cells. Our results also indicate a significant decrease in miR-381-3p expression levels in DOX-resistant ATC tissues and cell lines. miR-381-3p may function as a tumour suppressor to impede proliferation, migration and invasion and induce apoptosis of DOX-resistant SW1736 and CAL62 cells by inhibiting HOXA9 protein expression. Our results present a novel signalling axis miR-381-3p/HOXA9 that mediates DOX resistance in ATC. miR-381-3p and HOXA9 may be promising molecular targets for preventing ATC progression and drug resistance.

Circular RNA FOXO3 accelerates glycolysis and improves cisplatin sensitivity in lung cancer cells via the miR-543/Foxo3 axis

Non-small cell lung cancer (NSCLC) is the most common cause of cancer-associated mortality worldwide. Our previous study revealed that circular RNA (circRNA)-FOXO3 is highly expressed in lung cancer and inhibits cell proliferation. However, to the best of our knowledge, at present, no study has focused on the specific mechanism of circRNA-FOXO3 in drug resistance. Therefore, the present study aimed to provide novel perspectives on the role of circRNA-FOXO3 in cisplatin (DDP) resistance in NSCLC. A Cell Counting Kit-8 assay was used to determine the viability of cells overexpressed with circRNA-FOXO3 and under DDP treatment. Glycolysis was analyzed by measuring glucose consumption and lactate production. The interaction of circRNA-FOXO3, microRNA 543 (miR-543) and Foxo3 was confirmed using a dual-luciferase reporter assay. It was revealed that circRNA-FOXO3 improved cell sensitivity to DDP and repressed glycolysis in DDP-sensitive and DDP-resistant NSCLC cells. Bioinformatics analysis, luciferase reporter assays, quantitative PCR and RNA pull-down assays were employed to verify the binding of circRNA-FOXO3 to miR-543. Functionally, inhibition of miR-543 could sensitize NSCLC cells to DDP, and overexpression of miR-543 at least partially abolished the circRNA-FOXO3-induced decrease in chemoresistance. Furthermore, it was revealed that Foxo3 was a direct target of miR-543. Notably, the inhibitory action of miR-543 silencing on DDP resistance and glycolysis was reversed by overexpression of Foxo3 in DDP-sensitive and DDP-resistant NSCLC cells. In conclusion, the present study demonstrated that circRNA-FOXO3 promoted DDP sensitivity in NSCLC cells by regulating the miR-543/Foxo3 axis-mediated glycolysis balance. The present findings may provide novel perspectives for the treatment of patients with NSCLC resistant to DDP.

CiRS-7/CDR1as; An oncogenic circular RNA as a potential cancer biomarker

Circular RNAs (circRNAs) as a new class of non-coding RNAs (ncRNAs) play role in gene regulation in multicellular organisms via various interactions with nucleic acids, proteins and particularly microRNAs. They have been found to be involved in a number of biological functions particularly in regulation of cell cycle, and extracellular interactions. Thus, dysregulation of circRNAs is found to be associated with several human diseases and especially numerous types of cancers. ciRS-7 is an example of circRNAs which have been studied in a number of human diseases like neurological diseases, diabetes mellitus, and importantly different malignancies. It has been found to regulate cell proliferation and malignant features in cancer cells. CiRS-7 is upregulated in several cancers and its overexpression promoted malignant phenotype of cancer cells via enhancing cell proliferation, migration, and invasion in vitro and in vivo. As a competing endogenous RNA (ceRNA), ciRS-7 is found to sponge miR-7 as the most common miRNA target in interaction together. Functional analyses show role of ciRS-7 in downregulation of miR-7 and involvement of a series of signaling pathways in turn through them it is believed that ciRS-7 regulates malignant behaviors of cancer cells. Clinical studies demonstrate upregulation of ciRS-7 in cancer tissues compared to their non-cancerous adjacent tissues, correlation with worse clinicopathological features in cancerous patients and an independent prognostic factor. In this review, we have an overview to the role of ciRS-7 in development and progression of cancer and also assess its potentials as a diagnostic and prognostic biomarker in human cancers.

N1, N12-Diacetylspermine Is Elevated in Colorectal Cancer and Promotes Proliferation through the miR-559/CBS Axis in Cancer Cell Lines

N1, N12-Diacetylspermine (DiAcSpm) has been reported to be upregulated in the urine of cancer patients. Mass spectrometry has shown elevated DiAcSpm expressions in colorectal cancer (CRC) tissues. However, the diagnostic application of DiAcSpm is not available due to a lack of diagnostic grade antibodies. Also, its biological roles in CRC cells remain unexplored. In the present study, we developed an antibody that directly detected DiAcSpm expression in paraffin-embedded tissues. We also characterized its biological characteristics and underlying mechanisms. Polyclonal antibodies were generated by immunizing animals with a synthetic product of DiAcSpm. Antibody DAS AB016 showed strong sensitivity against DiAcSpm in CRC tissues. Immunohistochemistry results showed that DiAcSpm expression was significantly elevated in CRC tissues. High levels of DiAcSpm correlated with the clinical stage and Ki67 index. DiAcSpm treatment increased levels of proliferation, cell cycle progression, and cyclin D1 and cyclin E proteins in CRC cell lines, SW480 and Caco-2. DiAcSpm also upregulated ATP production in these two cell lines. RNA-sequencing showed that DiAcSpm downregulated miR-559, which was confirmed using RT-qPCR. The luciferase reporter assay, western blotting, and RT-qPCR showed that cystathionine β-synthase (CBS) was the target of miR-559. miR-559 inhibited, while CBS accelerated, CRC proliferation. In addition, CBS siRNA knockdown blocked the biological effects of DiAcSpm on CRC cells. In conclusion, DiAcSpm was found to be increased in CRC tissues using a newly developed antibody. DiAcSpm accelerated CRC proliferation by regulating the miR-559/CBS axis.