Circ-HMGA2 (hsa_circ_0027446) promotes the metastasis and epithelial-mesenchymal transition of lung adenocarcinoma cells through the miR-1236-3p/ZEB1 axis

Circ_0000758 Facilitates Bladder Cancer Cell Growth, Migration and Angiogenesis Via Severing as miR-1236-3p Sponge

Circular RNA (circRNA) has been reported to regulate the development of bladder cancer (BCa). However, the role of circ_0000758 in BCa progression is unknown. Circ_0000758 and miR-1236-3p expression, as well as ZEB2 mRNA expression were determined by qRT-PCR. BCa cell biological functions were determined by MTT assay, EdU assay, flow cytometry, wound healing assay and tube formation assay. Protein expression was detected by western blot analysis. RNA pull-down assay and dual-luciferase reporter assay were used to confirm RNA interaction. Xenograft mice models were constructed to assess the effect of circ_0000758 on BCa tumor growth. Circ_0000758 had increased expression in BCa tissues and cells. Circ_0000758 silencing could inhibit BCa cell growth, migration, angiogenesis in vitro, and tumor growth in vivo. Circ_0000758 served as a molecular sponge for miR-1236-3p, and miR-1236-3p inhibitor reversed circ_0000758 knockdown-mediated the inhibition effect on BCa cell progression. ZEB2 was targeted by miR-1236-3p, and its overexpression also revoked the suppressive effect of miR-1236-3p on BCa cell growth, migration, and angiogenesis. Besides, circ_0000758 knockdown also restrained BCa tumor growth. Circ_0000758 might promote BCa cell growth, migration, and angiogenesis by regulating the miR-1236-3p/ZEB2 axis.

The emerging role and mechanism of HMGA2 in breast cancer

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

Silencing of circ_0088036 inhibits growth and invasion of lung adenocarcinoma through miR-203/SP1 axis

Lung cancer is the leading cause of cancer-related deaths worldwide. Circular RNA (circRNA) circ_0088036 is a recently discovered circRNA known for its roles in rheumatoid arthritis. The study aimed to study the function of circ_0088036 in lung adenocarcinoma (LUAD). Circ_0088036 expressions were analyzed in the Gene Expression Omnibus (GEO) database. The relationship between circ_0088036 expressions and clinicopathological data of LUAD was assessed. The messenger RNA and protein levels were analyzed by quantitative real-time polymerase chain reaction and Western blot. Cell viability, apoptosis, and invasion were tested by Cell Counting Kit-8, flow cytometry, and transwell assay. The direct interaction between microRNA-203 (miR-203) and circ_0088036 or specificity protein 1 (SP1) was confirmed by dual-luciferase reporter assay, RNA pull-down, and RNA immunoprecipitation assays. Circ_0088036 was overexpressed in LUAD from the analysis of the GEO database. The poor prognosis was found in the patients with high expressions of circ_0088036. The level of Circ_0088036 was increased in LUAD tissues and cells. In terms of function, the deletion of circ_0088036 inhibited LUAD tumorigenesis in vitro by repressing cell growth, invasion, and epithelial-mesenchymal transition (EMT). In mechanism, circ_0088036 could competitively sponge miR-203, thereby affecting the expressions of the target gene SP1. In addition, lessening of miR-203 and enlarging of SP1 could eliminate the anticancer effect of short hairpin RNA-circ_0088036 on LUAD cells. Besides, the knockout of circ_0088036 hindered the growth of xenografted tumors in vivo. Circ_0088036 promoted the LUAD cell growth, invasion, and EMT via modulating the miR-203/SP1 axis in LUAD.

Circ_0027446 promotes malignant development of glioblastoma by interacting with miR-346 to up-regulate PGK1

Circular RNAs (circRNAs) can play essential roles in tumor development, including glioblastoma (GBM). The current study was performed to explore the function and mechanism of circ_0027446 in GBM progression. Circ_0027446, microRNA-346 (miR-346) and Phosphoglycerate kinase 1 (PGK1) levels were detected using reverse transcription-quantitative polymerase chain reaction assay. Cell behaviors were examined using Cell Counting Kit-8 assay, colony formation assay, EdU assay, flow cytometry, and transwell assay. Glycolytic metabolism was analyzed by commercial kits. The protein level was determined via western blot. The target interaction was analyzed by dual-luciferase reporter assay. Circ_0027446 function in vivo was explored by tumor xenograft assay. Circ_0027446 expression was significantly up-regulated in GBM samples and cells. Circ_0027446 down-regulation suppressed proliferation, invasion, glycolytic metabolism and enhanced apoptosis of GBM cells. MiR-346 was a target of circ_0027446, and circ_0027446 promoted GBM progression by sponging miR-346. PGK1 acted as a target gene of miR-346, and circ_0027446 interacted with miR-346 to regulate PGK1 expression. Overexpression of miR-346 inhibited malignant behaviors of GBM cells through down-regulating PGK1. Circ_0027446 contributed to tumor growth in vivo via miR-346/PGK1 axis. The current evidences demonstrated that circ_0027446 facilitated malignant progression of GBM through binding to miR-346 to up-regulate PGK1.

Paclitaxel-induced inhibition of NSCLC invasion and migration via RBFOX3-mediated circIGF1R biogenesis

We previously reported that circIGF1R is significantly downregulated in non-small cell lung cancer (NSCLC) cells and tissues. It inhibits cancer cell invasion and migration, although the underlying molecular mechanisms remain elusive. The invasion and migration of NSCLC cells was analyzed by routine in vivo and in vitro functional assays. Fluorescent in situ hybridization, luciferase reporter assay, RNA pull-down assay and RNA immunoprecipitation (RIP) assay were performed to explore the molecular mechanisms. Mechanism of action of paclitaxel-induced RBFOX3-mediated inhibition of NSCLC invasion and migration was investigated through in vitro and in vivo experiments.Our study reveals that circIGF1R acts as a Competing Endogenous RNA (ceRNA) for miR-1270, thereby regulating Van-Gogh-like 2 (VANGL2) expression and subsequently inhibiting NSCLC cell invasion and migration via the Wnt pathway. We also found that RNA binding protein fox-1 homolog 3 (RBFOX3) enhances circIGF1R biogenesis by binding to IGF1R pre-mRNA, which in turn suppresses migration and invasion in NSCLC cells. Additionally, the chemotherapeutic drug paclitaxel was shown to impede NSCLC invasion and migration by inducing RBFOX3-mediated circIGF1R biogenesis.RBFOX3 inhibits the invasion and migration of NSCLC cells through the circIGF1R/ miR-1270/VANGL2 axis, circIGF1R has the potential to serve as a biomarker and therapeutic target for NSCLC.

Regulation of Cervical Cancer Development by a Novel Circ_0000212/miR-1236-3p/GREM1 ceRNA Crosstalk

Circular RNAs (circRNAs) possess important functions in cervical carcinogenesis by operating as competing endogenous RNAs (ceRNAs). Our preliminary bioinformatics predicted the potential circ_0000212/microRNA (miR)-1236-3p/gremlin 1 (GREM1) ceRNA crosstalk. Thus, we further elucidated whether the novel ceRNA crosstalk can participate in cervical cancer development. Circ_0000212, miR-1236-3p and GREM1 were quantified by real-time quantitative polymerase chain reaction (qPCR) and immunoblotting. 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and tube formation assay were performed to assess cell proliferation, apoptosis and tube formation, respectively. Transwell assay was used to detect cell migration and invasion. Mouse xenografts were established to evaluate the role of circ_0000212 in vivo. Dual-luciferase reporter assay was performed to verify the direct relationship between miR-1236-3p and circ_0000212 or GREM1. Circ_0000212 expression was elevated in human cervical cancer. Silencing of endogenous circ_0000212 hindered cancer cell proliferation, motility and invasion and induced apoptosis, as well as diminished the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. Circ_0000212 silencing also weakened tumor growth in vivo. Mechanistically, circ_0000212 directly bound to miR-1236-3p, and downregulation of miR-1236-3p reversed these effects of circ_0000212 silencing on cell malignant phenotypes and HUVEC tube formation. GREM1 was a direct miR-1236-3p target, and its expression was regulated by circ_0000212 through miR-1236-3p. Moreover, miR-1236-3p upregulation impeded cancer cell malignant phenotypes and HUVEC tube formation by targeting GREM1. Our findings identify a novel ceRNA regulatory network, circ_0000212/miR-1236-3p/GREM1 axis, in cervical carcinogenesis, and provide potential targets that can be explored for therapeutic interventions.

Circ_0001715 Functions as a miR-1249-3p Sponge to Accelerate the Progression of Non-small Cell Lung Cancer via Upregulating the Level of FGF5

Circular RNAs (circRNAs) have been widely involved in the malignant development of human cancers. Circ_0001715 was aberrantly upregulated in non-small cell lung cancer (NSCLC). However, circ_0001715 function has never been researched. This study was designed to investigate the role and mechanism of circ_0001715 in NSCLC. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to examine the levels of circ_0001715, microRNA-1249-3p (miR-1249-3p) and Fibroblast Growth Factor 5 (FGF5). The proliferation detection was conducted using colony formation assay and EdU assay. Cell apoptosis was analyzed via flow cytometry. Wound healing assay and transwell assay were used for determination of migration and invasion, respectively. The protein levels were measured through western blot. Target analysis was carried out via dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Xenograft tumor model was established in mice for in vivo research. The significant upregulation of circ_0001715 was detected in NSCLC samples and cells. Circ_0001715 knockdown induced the inhibitory effects on proliferation, migration and invasion but the promoting effect on apoptosis of NSCLC cells. Circ_0001715 could interact with miR-1249-3p. The regulatory role of circ_0001715 was achieved by sponging miR-1249-3p. Furthermore, miR-1249-3p targeted FGF5 and miR-1249-3p acted as a cancer inhibitor by targeting FGF5. Moreover, circ_0001715 upregulated the FGF5 level via targeting miR-1249-3p. In vivo assay showed that circ_0001715 promoted the NSCLC progression through the miR-1249-3p/FGF5 axis. The current evidence elucidated that circ_0001715 served as an oncogenic regulator in NSCLC progression by depending on the miR-1249-3p/FGF5 axis.

Effect and mechanism of circHMGA2 on ferroptosis and pyroptosis in myocardial ischemia-reperfusion model CircHMGA2 exacerbates MI/R injury

Myocardial ischemia-reperfusion (MI/R) injury is a common and serious complication following reperfusion treatment for myocardial infarction (MI). Increasing evidence has verified the crucial role of circular RNAs (circRNAs) in the MI/R injury processes. The objective of this study was to investigate the effects and potential regulatory mechanisms of circHMGA2 on MI/R injury. Hypoxia/reoxygenation (H/R) models were established using human cardiac myocytes (HCMs) and mice models were induced by MI/R. The level of circHMGA2 was detected by RT-qPCR. Myocardial function was evaluated by the hemodynamic parameters, the activity of serum myocardial enzymes, HE staining and TUNEL assays. Cell proliferation was measured by CCK-8 assay. The ferrous ion (Fe²⁺) level was determined with an iron assay kit. Ferroptosis- and pyroptosis-related proteins were determined using western blotting. The levels of oxidative stress and inflammatory factors were analyzed using DCFH-DA staining or ELISA assays. CircHMGA2 was upregulated in H/R-induced HCMs and myocardial tissues of MI/R mice. In vitro, circHMGA2 knockdown attenuated the proliferation inhibition, restrained the ferroptosis and pyroptosis in H/R-induced HCMs. This regulatory mechanism may be associated with the suppression of NLRP3 pathway. In vivo, circHMGA2 depletion attenuated myocardial tissue damage of MI/R mice through inhibiting the oxidative stress and pyroptosis. Taken together, CircHMGA2 enhanced MI/R injury via promoting ferroptosis and pyroptosis, providing new insights into the treatment of MI/R injury.

CIRCULAR RNA CIRC_0099188 CONTRIBUTES TO LPS-INDUCED HPAEpiC CELL INJURY BY TARGETING THE MIR-1236-3P/HMGB3 AXIS

ABSTRACT

Purpose: This study is designed to explore the role and mechanism of circ_0099188 in LPS-engendered HPAEpiC cells. Methods: Circ_0099188, microRNA-1236-3p (miR-1236-3p), and high mobility group box 3 (HMGB3) levels were measured using real-time quantitative polymerase chain reaction. Cell viability and apoptosis were assessed using cell counting kit-8 (CCK-8) and flow cytometry assays. Protein levels of B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), cleaved-caspase 3, cleaved-caspase 9, and HMGB3 were determined using Western blot assay. IL-6, IL-8, IL-1β, and TNF-α levels were analyzed using enzyme-linked immunosorbent assays. After predicting using Circinteractome and Targetscan, the binding between miR-1236-3p and circ_0099188 or HMGB3 was verified using a dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays. Results: Circ_0099188 and HMGB3 were highly expressed, and miR-1236-3p was decreased in LPS-stimulated HPAEpiC cells. Also, the downregulation of circ_0099188 might overturn LPS-triggered HPAEpiC cell proliferation, apoptosis, and inflammatory response. Mechanically, circ_0099188 is able to affect HMGB3 expression by sponging miR-1236-3p. Conclusion: Circ_0099188 knockdown might mitigate LPS-induced HPAEpiC cell injury by targeting the miR-1236-3p/HMGB3 axis, providing an underlying therapeutic strategy for pneumonia treatment.

Exosomal circ-ADRM1 promotes lung adenocarcinoma progression and induces macrophage M2 polarization through regulating MMP14 mRNA and protein

OBJECTIVE

Lung adenocarcinoma (LUAD) is one of the frequent subtypes of lung cancer, featuring high rates of incidence and mortality. Matrix metalloproteinase 14 (MMP14) is known as a regulator in multiple cancers, whereas its upstream molecular mechanism remains to be investigated. This study aims to reveal the upstream molecular mechanism of MMP14 in LUSC progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were conducted to examine the levels of MMP14 mRNA and protein in LUAD cells, respectively. Cell counting kit-8 (CCK-8), transwell assay and wound healing assay were implemented to unveil LUAD cell proliferation, migration and invasion after indicated transfections. Flow cytometry analysis was applied to evaluate macrophage polarization. Mechanism experiments such as western blot, co-immunoprecipitation (Co-IP), RNA pulldown assay, luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay were used to explore relevant molecular mechanisms.

RESULTS

MMP14 facilitated LUAD cell proliferation, invasion and migration. MMP14 is the target gene of miR-1287-5p. Circ-ADRM1 upregulates MMP14 expression through sponging miR-1287-5p. Circ-ADRM1 recruits USP12 to impede the ubiquitination of MMP14 protein, thereby enhancing the stability of MMP14 protein. LUAD-derived exosomes induced macrophage M2 polarization by delivering circ-ADRM1.

CONCLUSIONS

Circ-ADRM1 promotes LUAD cell proliferation, invasion and migration through upregulating MMP14. Additionally, circ-ADRM1 induces macrophage M2 polarization in an exosome-dependent manner.

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.

CircKRT14 upregulates E2F3 by interacting with miR-1256 to act as an oncogenic factor in esophageal cancer

BACKGROUND

A growing number of studies have focused on the regulatory role of circular RNAs (circRNAs) in a variety of cancers. The purpose of this study was to investigate the effect of circRNA Keratin 14 (circKRT14) on the progression of esophageal cancer (EC).

METHODS

The levels of circKRT14, miR-1256 and E2F transcription factor 3 (E2F3) were analyzed by real-time quantitative polymerase chain reaction (qRT-PCR) and western blot. The circular structure of circKRT14 was confirmed by RNase R digestion assay. Cell apoptosis, migration and invasion were detected by flow cytometry and transwell assay. The protein levels of related factors were determined by western blot. The relationship between miR-1256 and circKRT14 or E2F3 was verified by dual-luciferase reporter assay. The in vivo function of circKRT14 was studied by xenograft tumor assay.

RESULTS

CircKRT14 was significantly increased in EC tissues and cells. CircKRT14 silencing inhibited EC cell proliferation, migration, and invasion, but promoted EC cell apoptosis in vitro. CircKRT1 acted as a sponge for miR-1256 in EC, and in-miR-1256 abolished the inhibitory effect of circKRT14 suppression on EC cell progression. E2F3 was a target of miR-1256 and functioned as an oncogene in EC cells. MiR-1256 curbed EC progression by downregulating E2F3. CircKRT14 could affect E2F3 expression by targeting miR-1256. CircKRT14 regulated EC progression in vivo through miR-1256/E2F3 axis.

CONCLUSIONS

These results uncovered that circKRT14 up-regulated the expression of E2F3 and promoted the malignant development of EC through sponging miR-1256.

Landscape of circular RNAs in different types of lung cancer and an emerging role in therapeutic resistance (Review)

Lung cancer is one of the most common malignant tumor types and the leading cause of cancer‑associated death worldwide. Different types of lung cancer exhibit differences in terms of pathophysiology and pathogenesis, and also treatment and prognosis. Accumulating evidence has indicated that circular RNAs (circRNAs) are abnormally expressed among different types of lung cancer and confer important biological functions in progression and prognosis. However, studies comparing different circRNAs in lung cancer subtypes are scarce. Furthermore, circRNAs have an important role in drug resistance and are related to clinicopathological features in lung cancer. Summaries of the association of circRNAs with drug resistance are also scarce in the literature. The present study outlined the biological functions of circRNAs and focused on discriminating differential circRNA patterns and mechanisms in three different types of lung cancer. The emerging roles of circRNAs in the resistance to chemotherapy, targeted therapy, radiotherapy and immunotherapy were also highlighted. Understanding these aspects of circRNAs sheds light on novel physiological and pathophysiological processes of lung cancer and suggests the application of circRNAs as biomarkers for diagnosis and prognosis, as well as therapeutic resistance.

Circ_0000808 promotes the development of non-small cell lung cancer by regulating glutamine metabolism via the miR-1827/SLC1A5 axis

Background

Circular RNA (circRNA) has been proved to be an important molecular target for cancer treatment. However, the function and molecular mechanism of circ_0000808 in non-small cell lung cancer (NSCLC) are still unclear.

Methods

Quantitative real-time PCR was used to detect the expression of circ_0000808, miR-1827, and solute carrier family 1 member 5 (SLC1A5). Cell proliferation, apoptosis, migration, and invasion were measured by cell counting kit 8 assay, colony formation assay, EdU staining, flow cytometry, wound healing assay, and transwell assay. The protein expression was measured by Western blot analysis. Dual-luciferase reporter assay and RIP assay were used to investigate the interactions between miR-1827 and circ_0000808 or SLC1A5. Cell glutamine metabolism was assessed by determining glutamine uptake, glutamate production, and α-ketoglutarate production. Xenograft mouse model was used to assess the in vivo effects of circ_0000808.

Results

Circ_0000808 expression was upregulated in NSCLC tissues and cancer cells, and its silencing inhibited NSCLC cell proliferation, migration, and invasion and led to apoptosis. Further results confirmed that circ_0000808 interacted with miR-1827 to positively regulate SLC1A5. The rescue experiments showed that miR-1827 inhibitor reversed the suppressive effect of circ_0000808 knockdown on the malignant behaviors of NSCLC cells. Also, SLC1A5 overexpression abolished the inhibition effect of miR-1827 on NSCLC cell progression. In addition, circ_0000808/miR-1827/SLC1A5 axis positively regulated the glutamine metabolism process in NSCLC cells. Moreover, circ_0000808 knockdown reduced the NSCLC tumor growth in vivo.

Conclusion

In summary, our data showed that circ_0000808 enhanced the progression of NSCLC by promoting glutamine metabolism through the miR-1827/SLC1A5 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02777-x.

Circ_0027446 induces CLDN1 expression to promote papillary thyroid cancer cell malignancy by binding to miR-129-5p

BACKGROUND

Previous data have shown that circular RNA (circRNA) is a key regulator in papillary thyroid cancer (PTC). However, the role and the detailed mechanism of circ_0027446 in PTC progression have not been reported.

METHODS

Circ_0027446, miR-129-5p, claudin 1 (CLDN1), C-myc and MMP2 expression were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR), Western Blot or immunohistochemistry (IHC) assay. Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. Cell proliferation was investigated by 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell colony formation assay. Cell apoptosis, invasion and migration were assessed by flow cytometry analysis, transwell assay and wound-healing assay, respectively. Dual-luciferase reporter assay was conducted to identify the associations among circ_0027446, miR-129-5p and CLDN1. The effect of circ_0027446 on PTC cell malignancy in vivo was revealed by a xenograft mouse model assay.

RESULTS

Circ_0027446 and CLDN1 expression were significantly upregulated, while miR-129-5p expression was downregulated in PTC tissues and cells. High circ_0027446 expression was closely associated with the poor prognosis of PTC patients. Circ_0027446 depletion inhibited PTC cell proliferation, migration and invasion but increased cell apoptosis. In addition, circ_0027446 acted as a miR-129-5p sponge, and miR-129-5p bound to CLDN1. Moreover, miR-129-5p inhibitors attenuated circ_0027446 depletion-induced effects in PTC cells. CLDN1 also participated in the regulation of miR-129-5p in PTC cell tumor properties. Importantly, circ_0027446 mediated CLDN1 expression by interacting with miR-129-5p. In vivo data showed that the decreased expression of circ_0027446 led to delayed tumor formation.

CONCLUSION

Circ_0027446 contributed to PTC cell tumor properties by regulating the miR-129-5p/CLDN1 pathway, showing circ_0027446 might be a therapeutic target in PTC.

The pivotal regulatory factor circBRWD1 inhibits arsenic exposure-induced lung cancer occurrence by binding mRNA and regulating its stability

Multiple studies have indicated that circular RNAs (circRNAs) play a regulatory role in different stages of tumors by interacting with various molecules. With continuous in-depth research on the biological functions of circRNAs, increasing evidence has shown that circRNAs play important roles in carcinogenesis caused by environmental pollutants. However, the function and mechanism of circRNAs in arsenic exposure-induced lung cancer occurrence have not been reported. In this study, RNA sequencing and qPCR assays revealed that the expression of circBRWD1 was decreased in BEAS-2B-As cells and multiple lung cancer cell lines. Silencing circBRWD1 promoted cell viability and proliferation, inhibited cell apoptosis, and accelerated the G0/G1 phase transition in BEAS-2B-As cells; however, these functions were abrogated by circBRWD1 overexpression. Mechanistically, under arsenic exposure, expression of decreased circBRWD1 led to enhanced stability of the mRNA to which it directly binds (c-JUN, c-MYC, and CDK6 mRNA), increasing its expression. This mechanism promotes the malignant transformation of lung cells and ultimately leads to lung cancer. Our findings thus reveal the molecular mechanism of arsenic carcinogenesis.

miR-17-5p/HOXA7 Is a Potential Driver for Brain Metastasis of Lung Adenocarcinoma Related to Ferroptosis Revealed by Bioinformatic Analysis

Objectives

Present study aims to identify the essential mRNAs responsible for the development of brain neurovascular-related metastases (BNM) among lung adenocarcinoma (LUAD) patients. Further, we attempted to predict brain metastases more accurately and prevent their development in LUAD patients.

Methods

Transcriptome data analysis was used to identify differentially expressed mRNAs (DEMs) associated with brain metastasis, and thereby the ferroptosis index (FPI) is calculated using a computational model. Meanwhile, the DEmRNAs linked with FPI, and brain metastasis were derived by the intersection of these two groups of DEMs. We also constructed a ceRNA network containing these DEmRNAs, identifying the HCP5 /hsa-miR-17-5p/HOXA7 axis for analysis. Further, a clinical cohort was employed to validate the regulatory roles of molecules involved in the ceRNA regulatory axis.

Results

Here we report the development of a ceRNA network based on BNM-associated DEMs and FPI-associated DEmRNAs which includes three core miRNAs (hsa-miR-338-3p, hsa-miR-429, and hsa-miR-17-5p), three mRNAs (HOXA7, TBX5, and TCF21), and five lncRNAs (HCP5, LINC00460, TP53TG1). Using gene set enrichment analysis (GSEA) and survival analysis, the potential axis of HCP5 /hsa-miR-17-5p/HOXA7 was further investigated. It is found that HOXA7 and ferroptosis index are positively correlated while inhibiting tumor brain metastasis. It may be that HCP5 binds competitively with miR-17-5p and upregulates HOXA7 to increase iron death limiting brain cancer metastases.

Conclusions

The expression of both HOXA7 and HCP5 is positively correlated with FPI, indicating a possible link between ferroptosis and BNM. According to the results of our study, the ferroptosis-related ceRNA HCP5 /hsa-miR-17-5p/HOXA7 axis may contribute to the development of BNM in LUAD patients.

Circular RNA and Its Roles in the Occurrence, Development, Diagnosis of Cancer

Circular RNAs (circRNAs) are non-coding single-stranded covalently closed circular RNA, mainly produced by reverse splicing of exons of precursor mRNAs (pre-mRNAs). The characteristics of high abundance, strong specificity, and good stability of circRNAs have been discovered. A large number of studies have reported its various functions and mechanisms in biological events, such as the occurrence and development of cancer. In this review, we focus on the classification, characterization, biogenesis, functions of circRNAs, and the latest advances in cancer research. The development of circRNAs as biomarkers in cancer diagnosis and treatment also provides new ideas for studying circRNAs research.

Circular RNA circ_0061140 accelerates hypoxia-induced glycolysis, migration, and invasion in lung adenocarcinoma through the microRNA-653/hexokinase 2 (HK2) axis

Circular RNA (circRNA) is considered to be an essential regulator of multiple human malignancies. However, the role and molecular mechanism of circ_0061140 in lung adenocarcinoma ((LUAD) remain elusive. The levels of circ_0061140, microRNA (miR)-653 and hexokinase 2 (HK2) were examined by RT-qPCR. Downstream targets of circ_0061140 were predicted by circinteractome website and verified by luciferase reporter and RIP assays. HK2 protein level was assessed via Western blotting. The migratory and invasive abilities of LUAD cells were assessed via wound healing and transwell assays. It was uncovered that circ_0061140 level was elevated in LUAD samples, and the high level of circ_0061140 was related to poor survival rate of LUAD patients. Circ_0061140 deletion inhibited glycolysis, migration and invasion of hypoxia-treated LUAD cells. Moreover, circ_0061140 could modulate HK2 level by absorbing miR-653. Furthermore, miR-653 silence or HK2 addition neutralized the effects of circ_0061140 knockdown on LUAD progression under hypoxia. This study elaborated that circ_0061140 accelerated hypoxia-triggered glycolysis, migration and invasion in LUAD cells via downregulating miR-653 and increasing HK2 expression.

Exosomal circSHKBP1 participates in non-small cell lung cancer progression through PKM2-mediated glycolysis

Non-small cell lung cancer (NSCLC) has a high morbidity and mortality, and it is imperative to explore the latent pathogenesis mechanism of NSCLC progression to find potential prognostic biomarkers and therapeutic targets. The present study aimed to explore the biological function of circSHKBP1 in NSCLC. circSHKBP1 was found to be upregulated in NSCLC tissues and cell lines and was enriched in exosomes derived from NSCLC cells. Exosomal circSHKBP1 enhanced the proliferation, migration, invasion, and stemness of NSCLC cells. miRNA-1294 was identified as a target for circSHKBP1, and circSHKBP1 upregulated PKM2 expression by sponging miR-1294. Exosomal circSHKBP1 regulated glycolysis through PKM2 in a HIF-1α-dependent manner in NSCLC cells and promoted M2 polarization and macrophage recruitment. Moreover, exosomal circSHKBP1 promoted NSCLC cell growth, metastasis, and M2 infiltration in vivo. Thus, exosomal circSHKBP1 participated in the progression of NSCLC via the miR-1294/PKM2 axis. circSHKBP1 may be potential biomarker for the diagnosis and treatment of NSCLC.

A Novel Circular RNA CircRFX3 Serves as a Sponge for MicroRNA-587 in Promoting Glioblastoma Progression via Regulating PDIA3

An increasing number of studies have indicated that circular RNAs (circRNAs) participate in the progression of numerous tumors. However, the functions of circRNAs in glioblastoma (GBM) remain largely unknown. In this study, we focused on a novel circRNA (hsa_circRFX3_003) that was spliced from RFX3, which we named circRFX3. We confirmed that the expression of circRFX3 was substantially increased in GBM cell lines and clinical GBM tissues. The results of a series of overexpression and knockdown assays indicated that circRFX3 could boost the proliferation, invasion, and migration of GBM cells. By performing dual-luciferase reporter gene and RNA pull-down assays, we verified that circRFX3 could sponge microRNA-587 (miR-587) to exercise its function as a competing endogenous RNA (ceRNA) in the development of GBM. In addition, PDIA3 was proven to be a downstream target of miR-587 and to regulate the Wnt/β-catenin pathway. In conclusion, circRFX3 could act as a cancer-promoting circRNA to boost the development of GBM and regulate the miR-587/PDIA3/β-catenin axis. This study might provide a novel target for the treatment of GBM with molecular therapy.

CircRNA_103948 inhibits autophagy in colorectal cancer in a ceRNA manner

Circular RNA (circRNA) is implicated in many types of cancer; however, the expression and role of circRNAs in colorectal cancer (CRC) remains poorly understood. In this study, a circRNA microarray assay was performed to detect abnormally expressed circRNAs in CRC, and tissue arrays were used to determine the prognosis for CRC patients. Cell counting kit-8, clone formation, wound healing, and transwell assays were used to evaluate cell functions in vitro, and a mouse subcutaneous tumor model was designed for in vivo analysis. Autophagy was observed using confocal laser scanning and transmission electron microscopy. The expression of circRNA, miRNA, and mRNA was detected using qPCR; western blot, RNA pull-down assay, RNA immunoprecipitation, and dual luciferase assessment were applied for mechanistic studies. We found that circRNA_103948 expression is upregulated in CRC tissues, compared with adjacent normal tissues, and associated with poor prognosis. Knockdown of circRNA_103948 suppressed CRC both in vitro and in vivo. Mechanistically, circRNA_103948 could directly bind to miR-1236-3p and relieve suppression of the target TPT1. Furthermore, circRNA_103948 inhibited autophagy of CRC cells. Taken together, circRNA_103948 knockdown inhibited CRC cell growth by targeting miR-1236-3p/TPT1 axis-mediated autophagy. Thus, the circRNA_103948/miR-1236-3p/TPT1 axis affects CRC progression via modulation of autophagy.

CircHAS2 promotes the proliferation, migration, and invasion of gastric cancer cells by regulating PPM1E mediated by hsa-miR-944

Gastric cancer (GC) is considered one of the most common gastrointestinal malignancies worldwide. Circular RNAs (circRNAs) are a new class of endogenous noncoding RNAs, which can be used as biomarkers and therapeutic targets for many tumors. However, the role and potential regulatory mechanisms of circRNAs in GC remain unclear. In this study, we demonstrated that a specific circRNA, circHAS2, was upregulated in GC tissues and cells and was positively correlated with tumor metastasis. In vitro experiments demonstrated that circHAS2 knockdown or the addition of hsa-miR-944 mimics inhibited the proliferation, migration, and invasion ability of GC cells and affected the epithelial-mesenchymal transition. In addition, hsa-miR-944 interacted with protein phosphatase, Mg2+/Mn2+-dependent 1E (PPM1E), and was found to be a target gene of circHAS2. The upregulation of PPM1E reversed the effects of circHAS2 knockout on GC cells. The circHAS2/hsa-miR-944/PPM1E axis may be involved in the progression of GC; thus, circHAS2 may be a potential biomarker and therapeutic target for GC.

Circular RNA Circ_0000677 promotes cell proliferation by regulating microRNA-106b-5p/CCND1 in non-small cell lung cancer

Recently, circular RNAs (circRNAs) have become an intense focus of research and large numbers of circRNAs have been identified, awaiting functional elucidation. Thus, the present study aims to examine the regulation of circRNAs and its molecular mechanism in lung cancer growth. Here, we show that circular RNA circ_0000677 was overexpressed and correlated with poor prognosis in non‐small cell lung cancer (NSCLC) patients. Functionally, circ_0000677 knockdown markedly inhibited proliferation of NSCLC cells by observing of immunofluorescence staining of Ki67, clone formation assay, and xenograft experiments. In mechanism, circ_0000677 acted as a sponge of microRNA-106b and further regulated CCDND1 gene expression in NSCLC cells by dual luciferase activity assay and their expression examination. Taken together, these findings suggest a role for circ_0000677/miR-106b/CCND1 regulation axis in promoting NSCLC growth and progression.

circ_0101802 functions as a sponge of miR-1236-3p to facilitate the proliferation, migration and invasion of colorectal cancer via regulating MACC1

Circular RNAs (circRNAs) have been shown to be involved in the progression of many diseases, including cancer. However, the role of circ_0101802 in the proliferation, migration and invasion of colorectal cancer (CRC) has not been studied. Our results showed that circ_0101802 was highly expressed in CRC tumor tissues and cells. Functional experiments suggested that circ_0101802 knockdown could inhibit the proliferation, migration and invasion of CRC cells in vitro and CRC tumorigenesis in vivo. In the terms of mechanism, we discovered that circ_0101802 could act as a sponge of miR-1236-3p, and miR-1236-3p could target MACC1. The rescue experiments revealed that miR-1236-3p inhibitor could reverse the inhibition effect of circ_0101802 silencing on CRC proliferation, migration and invasion, and MACC1 overexpression also could abolish the negative regulation of miR-1236-3p on CRC proliferation, migration and invasion. More important, our data confirmed that circ_0101802 sponged miR-1236-3p to positively regulate MACC1. In summary, our results revealed that circ_0101802 functioned as a tumor promoter in CRC, which could facilitate CRC proliferation, migration and invasion via regulating the miR-1236-3p/MACC1 axis.

hsa_circ_0008234 inhibits the progression of lung adenocarcinoma by sponging miR-574-5p

circRNAs are a novel type of noncoding RNA (ncRNA) that have been identified as an important regulator of gene expression and play a part in the progression of various diseases. However, the function of circ_0008234 in lung adenocarcinoma (LUAC) remains unknown. Through the GEO (Gene Expression Omnibus) database, circ_0008234 was first found to be downregulated in LUAC tissues. It could inhibit cell growth and accelerate apoptosis in vitro and in vivo. In terms of its possible mechanism, circ_0008234 mainly was present in the cytoplasm and competed with miR-574-5p to regulate RND3 (Rho family GTPase 3). Our results revealed that circ_0008234 inhibited the progression of LUAC through a competing endogenous RNA (ceRNA)-based mechanism and provided potential biomarkers and therapeutic targets for LUAC treatment.