Circ6834 suppresses non-small cell lung cancer progression by destabilizing ANHAK and regulating miR-873-5p/TXNIP axis.

BACKGROUND: Circular RNAs (circRNAs) play important roles in cancer progression and metastasis. However, the expression profiles and biological roles of circRNAs in non-small cell lung cancer (NSCLC) remain unclear. METHODS: In this study, we identified a novel circRNA, hsa_circ_0006834 (termed circ6834), in NSCLC by RNA-seq and investigated the biological role of circ6834 in NSCLC progression in vitro and in vivo. Finally, the molecular mechanism of circ6834 was revealed by tagged RNA affinity purification (TRAP), western blot, RNA immunoprecipitation, dual luciferase reporter gene assays and rescue experiments. RESULTS: Our results showed that circ6834 was downregulated in NSCLC tumor tissues and cell lines. Circ6834 overexpression inhibited NSCLC cell growth and metastasis both in vitro and in vivo, while circ6834 knockdown had the opposite effect. We found that TGF-ß treatment decreased circ6834 expression, which was associated with the QKI reduction in NSCLC cells and circ6834 antagonized TGF-ß-induced EMT and metastasis in NSCLC cells. Mechanistically, circ6834 bound to AHNAK protein, a key regulator of TGF-ß/Smad signaling, and inhibited its stability by enhancing TRIM25-mediated ubiquitination and degradation. In addition, circ6834 acted as a miRNA sponge for miR-873-5p and upregulated TXNIP gene expression, which together inactivated the TGF-ß/Smad signaling pathway in NSCLC cells. CONCLUSION: In conclusion, circ6834 is a tumor-suppressive circRNA that inhibits NSCLC progression by forming a negative regulatory feedback loop with the TGF-ß/Smad signaling pathway and represents a novel therapeutic target for NSCLC.

M2 Tumor-Associated Macrophages-Derived Exosomal MALAT1 Promotes Glycolysis and Gastric Cancer Progression.

M2-polarized tumor-associated macrophages (M2 TAMs) promote cancer progression. Exosomes mediate cellular communication in the tumor microenvironment (TME). However, the roles of exosomes from M2 TAMs in gastric cancer progression are unclear. Herein, it is reported that M2 TAMs-derived exosomes induced aerobic glycolysis in gastric cancer cells and enhanced their proliferation, metastasis, and chemoresistance in a glycolysis-dependent manner. It is identified that MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) is enriched in M2 TAM exosomes and confirmed that MALAT1 transfer from M2 TAMs to gastric cancer cells via exosomes mediates this effect. Mechanistically, MALAT1 interacted with the δ-catenin protein and suppressed its ubiquitination and degradation by ß-TRCP. In addition, MALAT1 upregulated HIF-1α expression by acting as a sponge for miR-217-5p. The activation of ß-catenin and HIF-1α signaling pathways by M2 TAM exosomes collectively led to enhanced aerobic glycolysis in gastric cancer cells. Finally, a dual-targeted inhibition of MALAT1 in both gastric cancer cells and macrophages by exosome-mediated delivery of siRNA remarkably suppressed gastric cancer growth and improved chemosensitivity in mouse tumor models. Taken together, these results suggest that M2 TAMs-derived exosomes promote gastric cancer progression via MALAT1-mediated regulation of glycolysis. The findings offer a potential target for gastric cancer therapy.

Circ1811 suppresses gastric cancer progression by regulating the miR-632/DAPK1 axis.

Compelling evidence has identified circRNAs as crucial regulators in initiation and progression of various cancers, including gastric cancer (GC). However, the function and regulatory mechanisms of circRNAs in GC remain largely unknown. In this study, attention is paid to a novel circular RNA circ1811, which exerts significant downregulated expression in GC tissues compared with adjacent non-cancerous tissues. The expression of circ1811 in GC tumor tissues is negatively correlated with the extent of lymphatic metastasis in GC patients. Overexpression of circ1811 inhibited GC cell proliferation, migration and invasion while promoting apoptosis, whereas knockdown of circ1811 led to the opposite effects. AGO2 RIP and dual luciferase reporter assays indicated that circ1811 directly sponges miR-632 to upregulate the expression of DAPK1. Collectively, circ1811 acts as a tumor-suppressor for GC progression by regulating the miR-632/DAPK1 axis. Our findings suggest the potential of circ1811 as ideal biomarker and therapeutic target for GC.

Circular RNAs as biomarkers and therapeutic targets for gastrointestinal cancers.

Circular RNAs are a class of noncoding RNAs with covalently linked 5' and 3' ends that arise from backsplicing events. The absence of a 5' cap and a 3' poly(A) tail makes circular RNAs relatively more stable than their linear counterparts. They are evolutionary conserved and tissue-specific, and some show disease-specific expression patterns. Although their biological functions remain largely unknown, circular RNAs have been shown to play regulatory roles by acting as microRNA sponges, regulators of RNA-binding proteins, alternative splicing, and parental gene expression, and they could even encode proteins. Over the past few decades, circular RNAs have attracted wide attention in oncology owing to their implications in various tumors. Many circular RNAs have been characterized as key players in gastrointestinal cancers and influence cancer growth, progression, metastasis, and therapeutic resistance. Accumulating evidence reveals that their unique characteristics, coupled with their critical roles in tumorigenesis, make circular RNAs promising non-invasive clinical biomarkers for gastrointestinal cancers. In the present review, we summarized the biological roles of the emerging circular RNAs and their potential as biomarkers and therapeutic targets, which may help better understand their clinical significance in the management of gastrointestinal cancers.

Engineering and Targeting Neutrophils for Cancer Therapy.

Neutrophils are the most abundant white blood cells in the circulation and act as the first line of defense against infections. Increasing evidence suggests that neutrophils possess heterogeneous phenotypes and functional plasticity in human health and diseases, including cancer. Neutrophils play multifaceted roles in cancer development and progression, and an N1/N2 paradigm of neutrophils in cancer is proposed, where N1 neutrophils exert anti-tumor properties while N2 neutrophils display tumor-supportive and immune-suppressive functions. Selective activation of beneficial neutrophil population and targeted inhibition or re-polarization of tumor-promoting neutrophils has shown an important potential in tumor therapy. In addition, due to the natural inflammation-responsive and physical barrier-crossing abilities, neutrophils and their derivatives (membranes and extracellular vesicles (EVs)) are regarded as advanced drug delivery carriers for enhanced tumor targeting and improved therapeutic efficacy. In this review, the recent advances in engineering neutrophils for drug delivery and targeting neutrophils for remodeling tumor microenvironment (TME) are comprehensively presented. This review will provide a broad understanding of the potential of neutrophils in cancer therapy.

Identification of differentially expressed miRNAs in plasma exosomes from patients with early-onset pre-eclampsia using next generation sequencing.

Pre-eclampsia (PE), a major cause of perinatal morbidity and mortality, accounts for up to 14 % mortality of maternal and 18 % of fetal or infant mortalities. However, the pathogenesis process of PE remains unclear. The aim of this study was to identify differentially expressed microRNAs (miRNAs) in the peripheral blood exosomes of early-onset PE patients versus healthy pregnant women using high-throughput sequencing, and to find candidate miRNAs as molecular markers. Methods: Peripheral blood samples were collected from five preeclamptic patients and five healthy women. Exosomal miRNAs were sequenced using the Illumina HiSeq4000 sequencing platform. The target gene prediction, biological function enrichment, and signaling pathway prediction of the miRNAs with significant differences were carried out using the Starbase database software, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively. Our results showed 65 significantly differentially expressed miRNAs in the exosomes of early-onset PE patients compared to control group, with 17 up-regulated and 48 down-regulated (P < 0.05). A total of 2231 target genes were predicted for all differentially expressed miRNAs. Biological functions enriched by these target genes were mainly associated with Ras protein signal transduction, GTPase-mediated signal transduction regulation, histone modification, and ß-transforming growth factor regulatory process. Key regulatory signaling pathways included TGF-ß signaling pathway, PI3K-Akt signaling pathway, MAPK signaling pathway, tumor necrosis factor signaling pathway and EGFR tyrosine kinase inhibition signaling pathways. QPCR validation in 40 independent samples for 10 miRNAs, identified three miRNAs were confirmed in the second population. MIR7151 was a most significant differentially expressed miRNAs, and predicted its downstream regulatory gene, KCNQ10T1, using Starbase software. There were significant differences in miRNA expression profiles between peripheral blood exosomes of early-onset PE patients and normal pregnant women, suggesting that these miRNAs may contribute to the pathophysiology of early-onset PE by regulating various biological functions and signaling pathways.

Exosomal miRNAs from neutrophils act as accurate biomarkers for gastric cancer diagnosis.

BACKGROUND: Gastric cancer (GC) is the third leading cause of cancer-related death worldwide. Sensitive and accurate biomarkers can greatly aid in early diagnosis and favorable prognosis. Neutrophils are the most abundant immune cells in human circulation and play a critical role in tumor progression. Neutrophil-derived exosomes (Neu-Exo) contain abundant bioactive molecules and are critically involved in disease progression. METHODS: We proposed a Dynabeads-based (CD66b antibody-coupled) separation and detection system for Neu-Exo analysis. Dual antibody-assisted fluorescent Dynabeads was established to detect Neu-Exo abundance. MiRNA signature of Neu-Exo was identified by RNA sequencing. QRT-PCR and droplet digital PCR (ddPCR) were used for candidate miRNA detection and the potential of Neu-Exo miRNAs in the diagnosis of gastric cancer was evaluated. RESULTS: Dual antibody-assisted fluorescent Dynabeads obtained a detection limit of 7.8 × 105 particles/mL of Neu-Exo and a recovery rate of 81 % under optimized conditions. ROC curve indicated that the abundance of CD66b+ Neu-Exo could well distinguish GC patients from healthy controls (HC) (AUC > 0.8). Additionally, miR-223-3p was found among the top differentially expressed miRNAs in Neu-Exo and presented superior diagnostic value in gastric cancer. Droplet digital PCR (ddPCR) significantly improved the diagnostic efficiency to differentiate GC patients from HC and benign gastric diseases (BGD) patients (AUC > 0.9). CONCLUSION: The Dynabeads-based separation and detection system, assisted with ddPCR analysis, provides a promising platform to enrich Neu-Exo and analyze miRNA profile for gastric cancer liquid biopsy.