Circular RNA circFGFR1 promotes progression and anti-PD-1 resistance by sponging miR-381-3p in non-small cell lung cancer cells

PIM3 Promotes the Proliferation and Migration of Acute Myeloid Leukemia Cells

Purpose

Acute myeloid leukemia (AML) is associated with a poor overall prognosis. PIM family genes, including PIM1, PIM2, and PIM3, are proto-oncogenes that are aberrantly overexpressed in different types of human cancers. In this study, we aimed to explore and clarify the function of PIM3 in AML.

Patients and Methods

The expression of the three PIM genes in AML was detected using the Gene Expression Omnibus. The expression of PIM3 and PIM3 in patient samples and AML cell lines was measured using quantitative real-time polymerase chain reaction or Western blot analyses. The cellular behaviors of PIM3-overexpressing AML cell lines were detected using a CCK-8 assay, flow cytometry, Western blotting, immunofluorescence staining, and a cell migration assay. The interactions between PIM3 and phosphorylated CXCR4 (pCXCR4) were explored via immunoprecipitation.

Results

Higher PIM3 expression was detected in primary AML cells than in healthy donor cells. Second, PIM3 overexpression promoted AML cell proliferation and protected against spontaneous apoptosis by phosphorylating BAD (pBAD) at Ser112. Furthermore, PIM3 overexpression might promote the migration of AML cells via CXCR4. PIM3-overexpressing AML cell lines exhibited increased CXCR4 phosphorylation at Ser339, and pCXCR4 interacted with PIM3.

Conclusion

Our findings suggest that PIM3 regulates the proliferation, survival, and chemotaxis of AML cell lines. Moreover, pCXCR4 might mediate the regulation of PIM3-induced chemotaxis. Therefore, the inhibition of PIM3 expression may be a promising therapeutic target in AML.

Circular RNAs: Regulatory functions in respiratory tract cancers

Circular RNAs (circRNAs) are a class of single-stranded RNAs having a covalently closed loop structure generated from back-splicing of pre-mRNA. These novel RNAs are characterized by high stability, abundance and conservation. Accumulating evidence has revealed that circRNAs are intimately associated with the pathogenesis, development and progression of multiple human diseases, including respiratory tract cancers. CircRNAs may serve as oncogenes or tumor suppressors to influence cell proliferation, differentiation, apoptosis, invasion and metastasis. CircRNAs may act as microRNA (miRNA) sponges, interact with RNA-binding proteins (RBPs), regulate gene transcription and/or translate into mini-peptides or proteins. In this review, we discuss recent progress in understanding the pathologic roles of circRNAs in respiratory tract cancers, such as nasopharyngeal carcinoma, laryngeal squamous cell carcinoma, and especially lung adenocarcinoma. We further discuss the diagnostic, therapeutic and prognostic roles as potential biomarkers in respiratory tract cancers, providing insight into the possibilities of applying circRNAs as therapeutic targets and biomarkers in precision oncology.

Small Extracellular Vesicles Containing miR-381-3p from Keratinocytes Promote T Helper Type 1 and T Helper Type 17 Polarization in Psoriasis

T helper cells are crucial for psoriasis pathogenesis. Communication between T cells and psoriatic keratinocytes (KCs) helps drive the Th1 and Th17 response, but the underlying mechanism is not well-understood. Small extracellular vesicles (sEVs) are emerging mediators of intercellular communication. Here, we investigated the role of KC-derived sEVs in the Th1 and Th17 response in psoriasis. We isolated and characterized sEVs from KCs under normal (untreated) and psoriatic (cytokine-treated) conditions. sEVs under both conditions exhibited a cup-shaped morphology and expressed markers CD63 and CD81. sEVs from cytokine-treated KCs can be taken up by CD4⁺T cells, leading to the induction of Th1 and Th17 polarization. Small RNA sequencing revealed that miR-381-3p was significantly increased in sEVs from cytokine-treated KCs and in CD4⁺T cells from patients with psoriasis. Moreover, sEVs-containing miR-381-3p was responsible for sEVs-induced Th1 and Th17 polarization. We further found that the miR-381-3p targeted to the 3' untranslated region of E3 ubiquitin-ligase UBR5 and stabilized RORγt protein expression. It also targeted to the 3' untranslated region of FOXO1, associated with activated T-bet and RORγt transcription. Taken together, we propose that psoriatic KCs transfer miR-381-3p to CD4⁺T cells through sEVs, inducing Th1 and Th17 polarization and promoting psoriasis development. Our findings motivate future studies of KC-derived sEVs or their specific cargoes as therapeutic candidates for psoriasis.

circ_0084927 promotes cervical carcinogenesis by sponging miR-1179 that suppresses CDK2, a cell cycle-related gene

Background

Cervical cancer (CC) is a malignant tumor found in the lowermost part of the womb. Evolving studies on CC have reported that circRNA plays a crucial role in CC progression. In this study, we investigated the main function of a novel circRNA, circ_0084927, and its regulatory network in CC development.

Methods

qRT-PCR was applied to evaluate the expression of circ_0084927, miR-1179, and CDK2 mRNA in CC tissues and cells. Dual-luciferase reporting experiments and RNA immunoprecipitation (RIP) assay were conducted to validate the target relationship of miR-1179 with circ_0084927 and CDK2 mRNA. CCK-8 and BrdU assays were also used to evaluate CC cell proliferation. The adhesion and apoptosis phenotypes of CC cells were measured using cell–matrix adhesion and caspase 3 activation assay. Flow cytometry was also employed to detect the CC cell cycle.

Results

Our results indicated that circ_0084927 was up-regulated in CC tissues and cells. Findings also revealed that circ_0084927 silence inhibited CC cell proliferation and adhesion while facilitating apoptosis and triggering cell cycle arrest. However, miR-1179 down-regulation appeared in CC tissues. Apart from observing that circ_0084927 abolished miR-1179’s inhibitory effects on cell proliferation and adhesion, it was found that CDK2 was up-regulated in CC tissues and was instrumental in cancer promotion. Also observed was that miR-1179 directly targeted CDK2, thereby inhibiting CDK2’s promotion on the malignant phenotypes of CC cells. Lastly, results indicated that circ_0084927 revoked the inhibitory effect of miR-1179 on CDK2 by sponging miR-1179.

Conclusion

circ_0084927 promoted cervical carcinogenesis by sequestering miR-1179, which directly targeted CDK2. Our results also provided novel candidate targets for CC treatment in that it revealed the circ_0084927/miR-1179/CDK2 regulatory network that strengthened CC aggressiveness.

Value of circular RNA 0007385 in disease monitoring and prognosis estimation in non-small-cell lung cancer patients

Objective

This study aimed to assess the circular RNA_0007385 (hsa_circ_0007385) expression in tumor/adjacent non‐tumor tissues, and the correlation of its tumor expression with clinicopathological features as well as survival in non–small‐cell lung cancer (NSCLC) patients.

Methods

210 NSCLC patients who underwent tumor resection were reviewed in this retrospective study. 210 tumor specimens and 81 paired adjacent specimens were collected, in which the hsa_circ_0007385 expression was detected by reverse transcription‐quantitative polymerase chain reaction assay. Disease‐free survival (DFS) and overall survival (OS) were recorded, and the last follow‐up date was June 30, 2019.

Results

Hsa_circ_0007385 was upregulated in tumor tissue compared with adjacent non‐tumor tissue (P < .001), and ROC curve analysis revealed that hsa_circ_0007385 expression had an excellent value in distinguishing tumor tissue from adjacent non‐tumor tissue with an area under curve of 0.922 (95% CI: 0.890‐0.953). Tumor hsa_circ_0007385 high expression correlated with lymph node metastasis (P = .007) and higher TNM stage (P = .004). In addition, DFS (P = .028) and OS (P = .008) were both less favorable in patients with tumor hsa_circ_0007385 high expression compared to patients with tumor hsa_circ_0007385 low expression. Besides, the DFS (P = .008) and OS (P = .012) were also the worst in patients with tumor hsa_circ_0007385 high+++ expression, followed by patients with tumor hsa_circ_0007385 high++ expression and patients with tumor hsa_circ_0007385 high + expression, and the best in patients with tumor hsa_circ_0007385 low expression. Multivariate regression analysis elucidated that tumor hsa_circ_0007385 high expression independently predicted worse OS (P = .033).

Conclusion

Tumor hsa_circ_0007385 could be a novel biomarker for disease monitoring and prognosis prediction in NSCLC patients.

Circular RNA circMBOAT2 promotes prostate cancer progression via a miR-1271-5p/mTOR axis

Patients with advanced prostate cancer (PCa) have poor prognosis. Circular RNAs (circRNAs) regulate biological processes in a variety of cancers, but the precise roles of circRNAs in PCa are poorly understood. Herein, we identified a novel circRNA, termed circMBOAT2 (has_circ_0007334), which was significantly overexpressed in PCa tissues and cell lines. Overexpression of circMBOAT2 was associated with high Gleason score, advanced pathological T stage, and poor prognosis. Overexpression of circMBOAT2 promoted proliferation, migration, and invasion of PCa cells in vitro, and enhanced tumorigenesis and metastasis in vivo. Mechanistically, circMBOAT2 overexpression upregulated the expression of mTOR by acting as a decoy for miR-1271-5p, resulting in the activation of the PI3K/Akt pathway, ultimately promoting the progression of PCa. Importantly, application of an inhibitor of mTOR significantly antagonized circMBOAT2-mediated PCa tumorigenesis in vivo. circMBOAT2 promotes proliferation and metastasis of PCa through miR-1271-5p/mTOR axis-mediated activation of the PI3K/Akt pathway. In summary, our findings uncover a molecular mechanism in the progression of PCa and indicate that circMBOAT2 may be a useful prognostic biomarker and therapeutic target in PCa.

Identification of epithelial-mesenchymal transition-related circRNA-miRNA-mRNA ceRNA regulatory network in breast cancer

BACKGROUND

Circular RNAs (circRNAs) have attracted lots of attention in tumorigenesis and progression. However, circRNAs as crucial regulators in epithelial-mesenchymal transition have not been systematically identified in breast cancer. The purpose of our research was to investigate the circRNA network associated with epithelial-mesenchymal transition in breast cancer.

METHODS

Expression profiling data of circRNAs were identified by circRNA microarray in transfected ZEB1 and control breast cancer cells. The differentially expressed circRNAs, miRNAs, and mRNAs were determined via fold change filtering. The competing endogenous RNAs (ceRNAs) network was established on the foundation of the relationship between circular RNAs, miRNAs and mRNAs. The CytoHubba was used to determine the hub genes from the protein-protein interaction (PPI) regulatory network. The GEPIA database was used to observe the expression of the hub genes mRNA between breast cancer tissues and normal tissues. The HPA database was applied to investigate the expression of six hub genes at the protein level. Morever, we further used Kaplan-Meier plotter to perform survival analysis of these hub genes.

RESULTS

The top three up-regulated differential expressed circRNAs were identified by circRNA microarray. Following the Real-time PCR validation of the three circRNAs, two circRNAs (hsa_circRNA_002082 and hsa_circRNA_400031) were selected for further analysis. After the predicted target miRNA, ten circRNA-miRNA interactions including two circRNAs and ten miRNAs were determined. Furthermore, the Venn diagram was used to intersect the predicted target genes and the differentially expressed genes, and screened 174 overlapped genes. Subsequently, we constructed a PPI network, and selecting six hub genes, containing KIF4A, CENPF, OIP5, ZWINT, DEPDC1, BUB1B. The mRNA expression levels of the six hub genes were obviously up-regulated in breast cancer. The protein expression levels of KIF4A, CENPF, OIP5, and DEPDC1 were significantly increased in breast cancer tissues. Moreover, the survival analysis results revealed that high expression of the six hub genes were obviously correlated with poor prognosis of breast cancer patients.

CONCLUSIONS

Our study constructed and analyzed a circRNA-associated ceRNA regulatory network and discovered that hsa_circRNA_002082 and hsa_circRNA_400031 may mechanism as ceRNAs to serve key roles in breast cancer epithelial-mesenchymal transition.

Cancer cell-derived exosomal circUHRF1 induces natural killer cell exhaustion and may cause resistance to anti-PD1 therapy in hepatocellular carcinoma

Objective

Natural killer (NK) cells play a critical role in the innate antitumor immune response. Recently, NK cell dysfunction has been verified in various malignant tumors, including hepatocellular carcinoma (HCC). However, the molecular biological mechanisms of NK cell dysfunction in human HCC are still obscure.

Methods

The expression of circular ubiquitin-like with PHD and ring finger domain 1 RNA (circUHRF1) in HCC tissues, exosomes, and cell lines was detected by qRT-PCR. Exosomes were isolated from the culture medium of HCC cells and plasma of HCC patients using an ultracentrifugation method and the ExoQuick Exosome Precipitation Solution kit and then characterized by transmission electronic microscopy, NanoSight and western blotting. The role of circUHRF1 in NK cell dysfunction was assessed by ELISA. In vivo circRNA precipitation, RNA immunoprecipitation, and luciferase reporter assays were performed to explore the molecular mechanisms of circUHRF1 in NK cells. In a retrospective study, the clinical characteristics and prognostic significance of circUHRF1 were determined in HCC tissues.

Results

Here, we report that the expression of circUHRF1 is higher in human HCC tissues than in matched adjacent nontumor tissues. Increased levels of circUHRF1 indicate poor clinical prognosis and NK cell dysfunction in patients with HCC. In HCC patient plasma, circUHRF1 is predominantly secreted by HCC cells in an exosomal manner, and circUHRF1 inhibits NK cell-derived IFN-γ and TNF-α secretion. A high level of plasma exosomal circUHRF1 is associated with a decreased NK cell proportion and decreased NK cell tumor infiltration. Moreover, circUHRF1 inhibits NK cell function by upregulating the expression of TIM-3 via degradation of miR-449c-5p. Finally, we show that circUHRF1 may drive resistance to anti-PD1 immunotherapy in HCC patients.

Conclusions

Exosomal circUHRF1 is predominantly secreted by HCC cells and contributes to immunosuppression by inducing NK cell dysfunction in HCC. CircUHRF1 may drive resistance to anti-PD1 immunotherapy, providing a potential therapeutic strategy for patients with HCC.

Circular RNA circSLC25A16 contributes to the glycolysis of non-small-cell lung cancer through epigenetic modification

Growing evidence has highlighted the roles of circular RNAs (circRNAs) in non-small-cell lung cancer (NSCLC), however, their roles in NSCLC glycolysis remains poorly understood. CircRNAs microarray profiles discovered a novel exon-derived circRNA, circSLC25A16 (hsa_circ_0018534), in NSCLC tissue samples. In NSCLC samples, high-expression of circSLC25A16 was associated with unfavorable prognosis. Cellular experiments revealed that circSLC25A16 accelerated the glycolysis and proliferation of NSCLC cells. Besides, circSLC25A16 knockdown repressed the in vivo growth by xenograft assays. RNA-fluorescence in situ hybridization (RNA-FISH) illustrated that circSLC25A16 and miR-488-3p were both located in cytoplasm. Mechanistic experiments demonstrated that circSLC25A16 interacts with miR-488-3p/HIF-1α, which activates lactate dehydrogenase A (LDHA) by facilitating its transcription. Collectively, present research reveals the crucial function of circSLC25A16 on NSCLC glycolysis through miR-488-3p/HIF-1α/LDHA, suggesting the underlying pathogenesis for NSCLC and providing a therapeutic strategy for precise treatment.

Hsa_circ_0018818 knockdown suppresses tumorigenesis in non-small cell lung cancer by sponging miR-767-3p

To identify potential therapeutic targets in non-small cell lung cancer NSCLC, we conducted a bioinformatics analysis of circRNAs differentially expressed between NSCLC tissues and adjacent normal tissues. Cell proliferation and apoptosis was assessed using CCK-8 and flow cytometry, respectively. A connection between hsa_circ_0018818 and miR-767-3p was confirmed in dual luciferase reporter assays. Gene and protein expression in NSCLC cells were measured using quantitative PCR and Western-blotting, respectively. And a xenograft tumor model was established to assess the function of hsa_circ_0018818 in NSCLC in vivo. Hsa_circ_0018818 was greatly upregulated in NSCLC tumor tissues. Knocking down hsa_circ_0018818 using a targeted shRNA inhibited the proliferation and invasiveness of NSCLC cells and induced their apoptosis via the miR-767-3p/Nidogen 1 (NID1) signaling axis. Hsa_circ_0018818 knockdown also inactivated Epithelial-mesenchymal transition (EMT) process and PI3K/Akt signaling. In summary, hsa_circ_0018818 knockdown inhibited NSCLC tumorigenesis in vitro and in vivo, which suggests it could potentially serve as a target for the treatment of NSCLC.

Non-Coding RNAs in Lung Tumor Initiation and Progression

Lung cancer is one of the deadliest forms of cancer affecting society today. Non-coding RNAs, such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), through the transcriptional, post-transcriptional, and epigenetic changes they impose, have been found to be dysregulated to affect lung cancer tumorigenesis and metastasis. This review will briefly summarize hallmarks involved in lung cancer initiation and progression. For initiation, these hallmarks include tumor initiating cells, immortalization, activation of oncogenes and inactivation of tumor suppressors. Hallmarks involved in lung cancer progression include metastasis and drug tolerance and resistance. The targeting of these hallmarks with non-coding RNAs can affect vital metabolic and cell signaling pathways, which as a result can potentially have a role in cancerous and pathological processes. By further understanding non-coding RNAs, researchers can work towards diagnoses and treatments to improve early detection and clinical response.

The role of cancer-derived microRNAs in cancer immune escape

During malignant transformation, accumulated somatic mutations endow cancer cells with increased invasiveness and immunogenicity. Under selective pressure, these highly immunogenic cancer cells develop multiple strategies to evade immune attack. It has been well established that cancer cells could downregulate the expression of major histocompatibility complex, acquire alterations in interferon pathway, and upregulate the activities of immune checkpoint pathways. Besides, cancer cells secret numerous cytokines, exosomes, and microvesicles to regulate the functions and abundances of components in the tumor microenvironment including immune effector cells and professional antigen presentation cells. As the vital determinant of post-transcriptional regulation, microRNAs (miRNAs) not only participate in cancer initiation and progression but also regulate anti-cancer immune response. For instance, some miRNAs affect cancer immune surveillance and immune escape by interfering the expression of immune attack-associated molecules. A growing body of evidence indicated that cancer-derived immune modulatory miRNAs might be promising targets to counteract cancer immune escape. In this review, we summarized the role of some miRNAs in cancer immune escape and discussed their potential clinical application as treatment targets.

Critical function of circular RNAs in lung cancer

Lung cancer is one of the main causes of cancer-related death in the world, especially due to its frequency and ineffective therapeutically approaches in the late stages of the disease. 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 (circRNAs), a type of RNA with covalently closed continuous loop structures that display high structural resistance and tissue specificity pointed toward a potential biomarker role. Current investigations have identified that circRNAs have a prominent function in the regulation of oncogenic pathways, by regulating gene expression both at transcriptional and post-transcriptional level. The aim of this review is to provide novel information regarding the implications of circRNAs in lung cancer, with an emphasis on the role in disease development and progression. Initially, we explored the potential utility of circRNAs as biomarkers, focusing on function, mechanisms, and correlation with disease progression in lung cancer. Further, we will describe the interaction between circRNAs and other non-coding species of RNA (particularly microRNA) and their biological significance in lung cancer. Describing the nature of these interactions and their therapeutic potential will provide additional insight regarding the altered molecular landscape of lung cancer and consolidate the potential clinical value of these circular transcripts. This article is categorized under: RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA in Disease and Development > RNA in Disease RNA in Disease and Development > RNA in Development.

Functions and mechanisms of circular RNAs in cancer radiotherapy and chemotherapy resistance

Circular RNAs (circRNAs), one type of non-coding RNA, were initially misinterpreted as nonfunctional products of pre-mRNA mis-splicing. Currently, circRNAs have been proven to manipulate the functions of diverse molecules, including non-coding RNAs, mRNAs, DNAs and proteins, to regulate cell activities in physiology and pathology. Accumulating evidence indicates that circRNAs play critical roles in tumor genesis, development, and sensitivity to radiation and chemotherapy. Radiotherapy and chemotherapy are two primary types of intervention for most cancers, but their therapeutic efficacies are usually retarded by intrinsic and acquired resistance. Thus, it is urgent to develop new strategies to improve therapeutic responses. To achieve this, clarification of the underlying mechanisms affecting therapeutic responses in cancer is needed. This review summarizes recent progress and mechanisms of circRNAs in cancer resistance to radiation and chemotherapy, and it discusses the limitations of available knowledge and potential future directions.