CircHN1 affects cell proliferation and migration in gastric cancer

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.

Knocking Down HN1 Blocks Helicobacter pylori-Induced Malignant Phenotypes in Gastric Mucosal Cells and Inhibits Gastric Cancer Cell Proliferation, Cytoskeleton Remodeling, and Migration

Helicobacter pylori (H. pylori) is implicated in the aberrant proliferation and malignant transformation of gastric mucosal cells, heightening the risk of gastric cancer (GC). HN1 is involved in the development of various tumors. However, precise mechanistic underpinnings of HN1 promoting GC progression in H. pylori remain elusive. The study collected 79 tissue samples of GC patients, including 47 with H. pylori-positive GC and 32 H. pylori-negative controls. Using human gastric epithelial cells (GES-1) and human gastric adenocarcinoma cells (HGC-27), the effect of overexpression / knocking down of HN1 and H. pylori infection was evaluated on cell function (proliferation, migration, apoptosis), cytoskeleton, and expression of cell malignant phenotype factors that promote the malignant biological behavior of cancer cells. The expression of HN1 in GC tissues is higher than that in paracancerous tissue and is closely related to infiltration, lymphatic metastasis, distant metastasis, survival, and H. pylori infection. Downregulation of HN1 effectively hinders the ability of H. pylori strains 26695 and SS1 to promote migration of GES-1 and HGC-27 cells, while lowering the expression of key indicators associated with malignant phenotype. Downregulated GSK3B, β-catenin, and Vimentin after knockdown Integrinβ1, but HN1 expression remained largely unchanged, when HN1 and Integrinβ1 were knocked down, GSK3B, β-catenin, and Vimentin expression were considerably reduced. Our research demonstrated the crucial role of HN1 in H. pylori-induced acquisition of a malignant phenotype in GES-1 cells. Knockdown of HN1 blocked the pathogenic mechanism of H. pylori-induced GC and downregulated the expression of GSK3Β, β-catenin and Vimentin via Integrin β1.

Expression of circular RNAs in myelodysplastic neoplasms and their association with mutations in the splicing factor gene SF3B1

Mutations in the splicing factor 3b subunit 1 (SF3B1) gene are frequent in myelodysplastic neoplasms (MDS). Because the splicing process is involved in the production of circular RNAs (circRNAs), we investigated the impact of SF3B1 mutations on circRNA processing. Using RNA sequencing, we measured circRNA expression in CD34+ bone marrow MDS cells. We defined circRNAs deregulated in a heterogeneous group of MDS patients and described increased circRNA formation in higher-risk MDS. We showed that the presence of SF3B1 mutations did not affect the global production of circRNAs; however, deregulation of specific circRNAs was observed. Particularly, we demonstrated that strong upregulation of circRNAs processed from the zinc finger E-box binding homeobox 1 (ZEB1) transcription factor; this upregulation was exclusive to SF3B1-mutated patients and was not observed in those with mutations in other splicing factors or other recurrently mutated genes, or with other clinical variables. Furthermore, we focused on the most upregulated ZEB1-circRNA, hsa_circ_0000228, and, by its knockdown, we demonstrated that its expression is related to mitochondrial activity. Using microRNA analyses, we proposed miR-1248 as a direct target of hsa_circ_0000228. To conclude, we demonstrated that mutated SF3B1 leads to deregulation of ZEB1-circRNAs, potentially contributing to the defects in mitochondrial metabolism observed in SF3B1-mutated MDS.

Exosomal hsa_circ_000200 as a potential biomarker and metastasis enhancer of gastric cancer via miR-4659a/b-3p/HBEGF axis

BACKGROUND

Exosome, a component of liquid biopsy, loaded protein, DNA, RNA and lipid gradually emerges as biomarker in tumors. However, exosomal circRNAs as biomarker and function mechanism in gastric cancer (GC) are not well understood.

METHODS

Differentially expressed circRNAs in GC and healthy people were screened by database. The identification of hsa_circ_000200 was verified by RNase R and sequencing, and the expression of hsa_circ_000200 was evaluated using qRT-PCR. The biological function of hsa_circ_000200 in GC was verified in vitro. Western blot, RIP, RNA fluorescence in situ hybridization, and double luciferase assay were utilized to explore the potential mechanism of hsa_circ_000200.

RESULTS

Hsa_circ_000200 up-regulated in GC tissue, serum and serum exosomes. Hsa_circ_000200 in serum exosomes showed better diagnostic ability than that of tissues and serum. Combined with clinicopathological parameters, its level was related to invasion depth, TNM staging, and distal metastasis. Functionally, knockdown of hsa_circ_000200 inhibited GC cells proliferation, migration and invasion in vitro, while its overexpression played the opposite role. Importantly, exosomes with up-regulated hsa_circ_000200 promoted the proliferation and migration of co-cultured GC cells. Mechanistically, hsa_circ_000200 acted as a "ceRNA" for miR-4659a/b-3p to increase HBEGF and TGF-β/Smad expression, then promoted the development of GC.

CONCLUSIONS

Our findings suggest that hsa_circ_000200 promotes the progression of GC through hsa_circ_000200/miR-4659a/b-3p/HBEGF axis and affecting the expression of TGF-β/Smad. Serum exosomal hsa_circ_000200 may serve as a potential biomarker for GC.

Hsa-miR-1248 suppressed the proliferation, invasion and migration of colorectal cancer cells via inhibiting PSMD10

Background

Lymph node metastasis (LNM) is a critical event during the colorectal cancer (CRC) development and is indicative of poor prognosis. Identification of molecular markers of LNM may facilitate better therapeutic decision-making.

Methods

Six pairs of CRC tissues and corresponding adjacent tissues [3 pairs diagnosed as pT1N0M0 (M_Low group) and 3 pairs diagnosed as pT4N2M0 (M_High group)] collected from CRC patients who underwent surgical resection were used. MicroRNA sequencing was performed to screen differential microRNAs involved in CRC LNM. The selected microRNAs were validated in CRC tissues and cell lines using qRT-PCR. The functions of candidate hsa-miR-1248 were evaluated by CCK-8, colony formation, and Transwell assay. The binding of hsa-miR-1248 with its target PSMD10 was confirmed by luciferase activity assay, and the expression of PSMD10 in tissues was detected by droplet digital polymerase chain reaction.

Results

Ninety-five miRNAs were downregulated in carcinoma tissues (M_Low and M_high groups) compared with the normal group. Their expression in M_High group was significantly lower compared with M_Low group. The top 3 were hsa-miR-635, hsa-miR-1248, and hsa-miR-668-3p. After validation in tissues/cell lines, only hsa- hsa-miR-1248 was decreased in high metastatic tissues or SW620 cells compared to low metastatic tissues or SW480 cells. Hsa-miR-1248 was found to inhibit CRC cell viability, proliferation, invasion, and migration. The tumor suppressor effect of has-miR-1248 in CRC cells was attenuated or enhanced by up-regulating or down-regulating PSMD10, respectively.

Conclusion

Hsa-miR-1248 may act as a tumor suppressor gene in CRC by targeting and inhibiting PSMD10, which provides a clue for CRC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10028-1.

MiR-1248: a new prognostic biomarker able to identify supratentorial hemispheric pediatric low-grade gliomas patients associated with progression

Background

Pediatric low-grade gliomas (pLGGs), particularly incompletely resected supratentorial tumours, can undergo progression after surgery. However to date, there are no predictive biomarkers for progression. Here, we aimed to identify pLGG-specific microRNA signatures and evaluate their value as a prognostic tool.

Methods

We identified and validated supratentorial incompletey resected pLGG-specific microRNAs in independent cohorts from four European Pediatric Neuro-Oncology Centres.

Results

These microRNAs demonstrated high accuracy in differentiating patients with or without progression. Specifically, incompletely resected supratentorial pLGGs with disease progression showed significantly higher miR-1248 combined with lower miR-376a-3p and miR-888-5p levels than tumours without progression. A significant (p < 0.001) prognostic performance for miR-1248 was reported with an area under the curve (AUC) of 1.00. We also highlighted a critical oncogenic role for miR-1248 in gliomas tumours. Indeed, high miR-1248 levels maintain low its validated target genes (CDKN1A (p21)/FRK/SPOP/VHL/MTAP) and consequently sustain the activation of oncogenic pathways.

Conclusions

Altogether, we provide a novel molecular biomarker able to successfully identify pLGG patients associated with disease progression that could support the clinicians in the decision-making strategy, advancing personalized medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-022-00389-x.

Identification of circRNA-miRNA-Immune-Related mRNA Regulatory Network in Gastric Cancer

The pathogenesis of gastric cancer (GC) is still not fully understood. We aimed to find the potential regulatory network for ceRNA (circRNA–miRNA–immune-related mRNA) to uncover the pathological molecular mechanisms of GC. The expression profiles of circRNA, miRNA, and mRNA in gastric tissue from GC patients were downloaded from the Gene Expression Omnibus (GEO) datasets. Differentially expressed circRNAs, miRNAs, and immune-related mRNAs were filtered, followed by the construction of the ceRNA (circRNA–miRNA–immune-related mRNA) network. Functional annotation and protein–protein interaction (PPI) analysis of immune-related mRNAs in the network were performed. Expression validation of circRNAs and immune-related mRNAs was performed in the new GEO and TCGA datasets and in-vitro experiment. A total of 144 differentially expressed circRNAs, 216 differentially expressed miRNAs, and 2,392 differentially expressed mRNAs were identified in GC. Some regulatory pairs of circRNA–miRNA–immune-related mRNA were obtained, including hsa_circ_0050102–hsa-miR-4537–NRAS–Tgd cells, hsa_circ_0001013–hsa-miR-485-3p–MAP2K1–Tgd cells, hsa_circ_0003763–hsa-miR-145-5p–FGF10–StromaScore, hsa_circ_0001789–hsa-miR-1269b–MET–adipocytes, hsa_circ_0040573–hsa-miR-3686–RAC1–Tgd cells, and hsa_circ_0006089–hsa-miR-5584-3p–LYN–neurons. Interestingly, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN had potential diagnostic value for GC patients. In the KEGG analysis, some signaling pathways were identified, such as Rap1 and Ras signaling pathways (involved NRAS and FGF10), Fc gamma R-mediated phagocytosis and cAMP signaling pathway (involved RAC1), proteoglycans in cancer (involved MET), T-cell receptor signaling pathway (involved MAP2K1), and chemokine signaling pathway (involved LYN). The expression validation of hsa_circ_0003763, hsa_circ_0004928, hsa_circ_0040573, FGF10, MET, NRAS, RAC1, MAP2K1, and LYN was consistent with the integrated analysis. In conclusion, the identified ceRNA (circRNA–miRNA–immune-related mRNA) regulatory network may be associated with the development of GC.

Metformin and ICG-001 Act Synergistically to Abrogate Cancer Stem Cells-Mediated Chemoresistance in Colorectal Cancer by Promoting Apoptosis and Autophagy

Simple Summary

Colorectal cancer (CRC) is one of the most frequently diagnosed and lethal malignancies. The majority of CRC patients experience disease relapse after the primary curative treatment strategy of surgery followed by 5FU-based chemotherapy. The presence of cancer stem-like cells (CSCs) is considered to be one of the contributing factors to therapy resistance and disease relapse in CRC. Previous studies implicated the role of the Wnt signaling pathway in the maintenance of the CSC phenotype. Therefore, in this study we explored a novel therapeutic strategy using metformin along with ICG-001, a Wnt signaling inhibitor, to abrogate CSC-mediated chemoresistance in CRC. We observed that metformin and ICG-001 abrogate stemness in a synergistic manner by promoting autophagy and apoptosis in 5FU-resistant CRC cells as well as in CRC patient-derived tumor organoids. Hence, metformin and ICG-001 can be used as part of a therapeutic strategy to overcome 5FU-mediated therapeutic resistance in CRC.

Abstract

Colorectal cancer (CRC) remains the third most frequently diagnosed cancer in the United States. The current treatment regimens for CRC include surgery followed by 5FU-based chemotherapy. Cancer stem-like cells (CSCs) have been implicated in 5FU-mediated chemoresistance, which leads to poor prognosis. In this study, we used metformin along with ICG-001, a Wnt signaling inhibitor, to abrogate CSC-mediated chemoresistance in CRC. We observed that 5FU-resistant (5FUR) CRC cells exhibited increased expression of CSC markers and enhanced spheroid formation. Genome-wide transcriptomic profiling analysis revealed that Wnt signaling, colorectal cancer metastasis signaling, etc., were enriched in 5FUR CRC cells. Accordingly, selective targeting of Wnt signaling using ICG-001 along with metformin abrogated CSC-mediated chemoresistance by decreasing the expression of CSC markers and promoting autophagy and apoptosis in a synergistic manner. We also observed that metformin and ICG-001 exhibited anti-tumor activity in CRC patient-derived tumor organoids. In conclusion, our study highlights that metformin and ICG-001 act synergistically and can be used as part of a therapeutic strategy to overcome 5FU-mediated therapeutic resistance in CRC.

Diagnostic efficacy of circular RNAs as noninvasive, liquid biopsy biomarkers for early detection of gastric cancer

BACKGROUND

Majority of gastric cancers (GC) are diagnosed at advanced stages which contributes towards their poor prognosis. In view of this clinical challenge, identification of non-invasive biomarker for early diagnosis is imperative. Herein, we aimed to develop a non-invasive, liquid-biopsy based assay by using circular RNAs (circRNAs) as molecular biomarkers for early detection of GC.

METHODS

We performed systematic biomarker discovery and validation of the candidate circRNAs in matched tissue specimens of GC and adjacent normal mucosa. Next, we translated the discovered circRNA based biomarker panel into serum samples in a training and validation cohort of GC patients (n = 194) and non-disease controls (n = 94) and evaluated their diagnostic performance. In addition, we measured the expression of circRNAs in serum samples of pre- and post-surgical GC patients and evaluated the specificity of circRNAs biomarker panel with respect to other gastro-intestinal (GI) malignancies.

RESULTS

We identified 10-circRNAs in the discovery phase with subsequent validation in a pilot cohort of GC tissue specimens. Using a training cohort of patients, we developed an 8-circRNA based risk-prediction model for the diagnosis of GC. We observed that our biomarker panel robustly discriminated GC patients from non-disease controls with an AUC of 0.87 in the training, and AUC of 0.83 in the validation cohort. Notably, the biomarker panel could robustly identify even early-stage GC patients, regardless of their tumor histology (diffuse vs. intestinal). The decreased expression of circRNAs in post-surgery serum specimens indicated their tumor-specificity and their potential source of origin in the systemic circulation.

CONCLUSIONS

We identified a panel of 8-circRNAs as non-invasive, liquid-biopsy biomarkers which might serve as potential diagnostic biomarkers for the early detection of GC.

Circ_0006948 Contributes to Cell Growth, Migration, Invasion and Epithelial-Mesenchymal Transition in Esophageal Carcinoma

BACKGROUND

Circular RNAs (circRNAs) can act as promoters or inhibitors in cancer progression. Has_circ_0006948 (circ_0006948) was reported to aggravate the malignant behaviors of esophageal carcinoma (EC).

AIMS

This study focused on investigating the molecular mechanism of circ_0006948 in EC progression.

METHODS

The quantitative real-time polymerase chain reaction was performed to detect the expression of circ_0006948, microRNA-4262 (miR-4262) and fibronectin type III domain containing 3B (FNDC3B). Cell growth analysis was conducted by Cell Counting Kit-8 and colony formation assays. Cell migration and invasion were assessed by transwell assay. Epithelial-mesenchymal transition (EMT)-associated proteins and FNDC3B protein expression were assayed using western blot. Dual-luciferase reporter and RNA pull-down assays were performed to validate the target combination. Xenograft tumor assay was used for investigating the role of circ_0006948 in vivo.

RESULTS

Circ_0006948 was upregulated in EC tissues and cells. Downregulating the expression of circ_0006948 or FNDC3B repressed cell growth, migration, invasion and EMT in EC cells. Target analysis indicated that miR-4262 was a target for circ_0006948 and FNDC3B was a downstream gene for miR-4262. Moreover, circ_0006948 could affect the expression of FNDC3B via sponging miR-4262. The effects of si-circ_0006948#1 on EC cells were partly restored by miR-4262 inhibition or FNDC3B overexpression. In addition, circ_0006948 also facilitated EC tumorigenesis in vivo by targeting the miR-4262/FNDC3B axis.

CONCLUSION

Taken together, circ_0006948 functioned as an oncogenic factor in EC by the miR-4262-mediated FNDC3B expression regulation.

Circ_PGPEP1 Serves as a Sponge of miR-1297 to Promote Gastric Cancer Progression via Regulating E2F3

BACKGROUND

Circular RNA (circRNA) is a special kind of noncoding RNA that plays a vital function in the progression of gastric cancer (GC). However, the role of a new circRNA, circ_PGPEP1, in GC is unclear.

AIMS

Exploring the role and mechanism of circ_PGPEP1 in GC progression.

METHODS

The expression levels of circ_PGPEP1, miR-1297, and E2F transcription factor 3 (E2F3) were determined using quantitative real-time PCR. Flow cytometry, colony formation assay, MTT assay, and transwell assay were used to evaluate cell cycle, apoptosis, proliferation, migration, and invasion. The protein levels of apoptosis-related markers and E2F3 were measured by western blot analysis. The interaction between circ_PGPEP1 and miR-1297 or miR-1297 and E2F3 was confirmed by dual-luciferase reporter assay. In addition, animal experiments were performed to assess the effect of circ_PGPEP1 on GC tumor growth in vivo.

RESULTS

Circ_PGPEP1 was a highly expressed circRNA in GC. Loss-of-function experiment indicated that circ_PGPEP1 silencing could induce cell cycle arrest and apoptosis, while inhibit proliferation, migration, and invasion in GC cells. MiR-1297 could be sponged by circ_PGPEP1, and its expression was downregulated in GC. MiR-1297 inhibitor could reverse the negatively regulation of circ_PGPEP1 knockdown on GC progression. Furthermore, we also found that E2F3 could be targeted by miR-1297, and its expression was positively regulated by circ_PGPEP1. Overexpression of E2F3 could invert the inhibitory effect of miR-1297 on GC progression. Animal experiments suggested that silenced circ_PGPEP1 could reduce GC tumor growth.

CONCLUSION

Our research showed that circ_PGPEP1 might serve as a potential biomarker for GC.

Downregulation of circular RNA circ-HN1 suppressed the progression of gastric cancer through the miR-485-5p/GSK3A pathway

Gastric cancer (GC) is a malignancy with high incidence and mortality globally. Circular RNAs (circRNAs) are reported to regulate cellular processes in human diseases, including GC. Herein, the functions of circ-HN1 and its molecular mechanisms were investigated. circ-HN1, miR-485-5p, and GSK3A levels in GC were measured using Real time-quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was analyzed using cell counting kit-8 (CCK-8) and colony formation assays. Meanwhile, the migration and invasion abilities were analyzed using the transwell assay. The targeted relationship was confirmed using a luciferase reporter assay and an RNA pull-down assay. In both GC tissues and cells, circ-HN1 expression was upregulated, and its silencing suppressed cellular processes. Moreover, circ-HN1 served as a sponge of miR-485-5p, which was reduced in patients with GC and negatively regulated by circ-HN1 in GC cells. Inhibition of miR-485-4p abolished the biological functions induced by the silencing of circ-HN1. Additionally, miR-485-5p targeted GSK3A in GC, whose expression was elevated in tumor tissues and was negatively correlated with miR-485-5p in tumor cells. GSK3A rescued the inhibition of miR-485-5p in the cellular processes. In conclusion, silencing of the circ-HN1–miR-485-5p–GSK3A regulatory network inhibited GC cell proliferation, migration, and invasion, suggesting that circ-HN1 is a potential target for GC therapy.

Reduced expression of circRNA hsa_circ_001888 in gastric cancer and its clinical significance

Background

Circular RNAs (circRNAs) are a novel family of endogenous RNAs. Recent studies have demonstrated that circRNAs are potential novel biomarkers for diagnosing cancers. However, little is known about the role of circRNAs in gastric cancer (GC). This study aimed to identify the relationship between GC and a new circRNA named hsa_circ_001888.

Methods

Hsa_circ_001888 expression levels were measured by quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) in GC cell lines, tissues, and plasma samples. Then, the associations between the expression level of hsa_circ_001888 and the clinicopathological features of patients with GC were further investigated. A receiver operating characteristic (ROC) curve was generated to evaluate the diagnostic value of hsa_circ_001888.

Results

In this study, hsa_circ_001888 was first found to be significantly downregulated in GC cell lines (AGS and MKN‐45), tissues, and plasma samples compared to control samples. Clinicopathological features showed that the expression of hsa_circ_001888 in GC tissues was associated with differentiation and in GC plasma linked with serum CEA and CA19‐9 levels. The areas under the ROC curves of hsa_circ_001888 in tissues and plasma were 0.654 and 0.66, respectively.

Conclusions

Hsa_circ_001888 may serve as a potential biomarker in the diagnosis of GC and may be involved in GC development.

Circular RNA hsa_circ_0001874 is an indicator for gastric cancer

BACKGROUND

Recent studies have indicated that circular RNAs (circRNAs) are novel endogenous RNAs whose 5' and 3' ends are covalently linked and play critical roles in gastric carcinogenesis. However, the significance of circRNA hsa_circ_0001874 in gastric cancer (GC) is still unclear.

METHODS

Therefore, we first detected hsa_circ_0001874 levels in GC cell lines and tissues and analyzed their potential correlation with clinicopathological factors. Then, a receiver operating characteristic (ROC) curve was established to evaluate its clinical value. Finally, we further predicted the biological functions of this molecule by bioinformatics analysis.

RESULTS

Our data showed that as an indicator, hsa_circ_0001874 expression was significantly decreased in 78.02% (71/91) of the GC patients. Combined with clinicopathological factors, the hsa_circ_0001874 level was strongly associated with cell differentiation (p < 0.001), tumor stage (p = 0.005), invasion (p = 0.024), lymphatic metastasis (p = 0.023), and CEA level (p < 0.001) in GC tissues. The area under the curve (AUC) was up to 0.673, with a sensitivity and specificity of 61.54% and 68.13%, respectively. Bioinformatics analysis showed that hsa_circ_0001874 harbors miR-593-5p, miR-103a-3p, and miR-107 seed sequences to regulate these three miRNAs and downstream target genes and exert its various biological functions in the carcinogenesis and progression of GC.

CONCLUSION

In summary, these data suggest that hsa_circ_0001874 is an indicator of GC and plays a significant role in gastric carcinogenesis and progression.

Circ-PITX1 Promotes the Progression of Non-Small Cell Lung Cancer Through Regulating the miR-1248/CCND2 Axis

Background

Circular RNA (circRNA) is a key regulator of cancer, and it has been proved to be involved in the regulation of cancer progression including non-small cell lung cancer (NSCLC). Circ-PITX1 was found to be a significantly upregulated circRNA in NSCLC, and its role and potential mechanism in NSCLC progression deserve further investigation.

Methods

The expression levels of circ-PITX1, microRNA (miR)-1248 and cyclin D2 (CCND2) were examined by quantitative real-time PCR (qRT-PCR). Cell proliferation, apoptosis, cell cycle process, migration and invasion were determined using cell counting kit 8 (CCK8) assay, colony formation assay, flow cytometry, wound healing assay and transwell assay. Xenograft models were built to explore the role of circ-PITX1 in NSCLC tumor growth in vivo. The glycolysis and glutamine metabolism of cells were assessed by detecting the consumptions of glucose and glutamine, cell extracellular acidification rate (ECAR), and the productions of lactate, α-ketoglutaric acid (α-KG) and ATP. The protein levels of hexokinase 2 (HK-2), glutaminase 1 (GLS1) and CCND2 were tested by Western blot (WB) analysis. Dual-luciferase reporter assay and RIP assay were employed to verify the interaction between miR-1248 and circ-PITX1 or CCND2.

Results

Circ-PITX1 was upregulated in NSCLC and its silencing could inhibit the proliferation, migration, invasion, cell cycle process, glycolysis, glutamine metabolism, and promote the apoptosis of NSCLC cells in vitro, as well as reduced tumor growth in vivo. In the terms of mechanism, we found that circ-PITX1 could act as a sponge of miR-1248, and miR-1248 could target CCND2. In addition, miR-1248 inhibitor reversed the inhibitory effect of circ-PITX1 knockdown on NSCLC progression. Similarly, CCND2 overexpression also reversed the suppressive effect of miR-1248 on NSCLC progression. Moreover, circ-PITX1 positively regulated CCND2 expression by sponging miR-1248.

Conclusion

Circ-PITX1 served as a sponge of miR-1248 to promote NSCLC progression by upregulating CCND2.

Circular RNA circ_HN1 facilitates gastric cancer progression through modulation of the miR-302b-3p/ROCK2 axis

Gastric cancer (GC) is a malignant tumor with high morbidity and mortality in the world. Circular RNA hsa_circHN1_005 (circ_HN1), also termed as hsa_circ_0045602, is reported as an oncogene in GC. However, the molecular mechanism of circ_HN1 in GC development has not been fully explored. Here, we surveyed the regulatory mechanism of circ_HN1 in GC progression. The levels of circ_HN1, miR-302b-3p, and rho-associated coiled-coil containing protein kinase 2 (ROCK2) mRNA were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, apoptosis, colony formation, cell cycle progresion, migration, and invasion were determined by using cell counting, flow cytometry, colony formation, or transwell assays. Protein levels were detected with Western blotting. The relationship between circ_HN1 or ROCK2 and miR-302b-3p was verified via dual luciferase reporter or RNA immunoprecipitation (RIP) assays. The role of circ_HN1 in vivo was confirmed by xenograft assay. We observed that circ_HN1 and ROCK2 were upregulated while miR-302b-3p was downregulated in GC tissues and cells. Circ_HN1 silencing slowed tumor growth in vivo and impeded cell proliferation migration, invasion, and facilitated cell apoptosis in GC cells in vitro. Circ_HN1 sponged miR-302b-3p to regulate ROCK2 expression. MiR-302b-3p inhibitor reversed circ_HN1 silencing-mediated influence on the malignant behaviors of GC cells. Furthermore, ROCK2 overexpression restored miR-302b-3p mimic-mediated impacts on cell malignant behaviors in GC cells. In conclusion, circ_HN1 exerted an oncogenic role in GC through upregulating ROCK2 via sponging miR-302b-3p, offering evidence that circ_HN1 is a potential target for GC therapy.

CircHN1 affects cell proliferation and migration in gastric cancer

Background

Increasing evidence indicates that circular RNAs (circRNAs) are dysregulated in human cancers. The biological roles of circRNAs in gastric cancer (GC) have not been well‐characterized.

Methods

The GEO database was used to analyze circRNA expression profile in GC. The expression level of target circRNA in tumor tissues and adjacent non‐tumor tissues was detected by reverse transcription‐quantitative PCR. Gene transfection was used to manipulate the expression of circRNAs. The biological roles of circRNAs in cell proliferation, migration, and invasion were determined by cell counting, colony formation, transwell migration, Matrigel invasion, and mouse xenograft tumor assays. The interactions between circRNAs and miRNAs were verified by RNA immunoprecipitation and luciferase reporter assays.

Results

We found that circHN1 was upregulated in GC tissues and cell lines compared to adjacent non‐tumor tissues and normal gastric epithelial cells. Additionally, circHN1 silencing significantly promoted GC cell growth, colony formation, migration, and invasion, whereas circHN1 overexpression had the opposite effects. CircHN1 overexpression also suppressed gastric cancer growth in the mouse xenograft tumor model. CircHN1 was mainly localized in the cytoplasm of GC cells and could bind to AGO2. MiR‐1248 and miR‐375 were predicted to interact with circHN1 by bioinformatic analyses. MiR‐1248 and miR‐375 overexpression inhibited the activity of the circHN1 luciferase reporter.

Conclusion

CircHN1 is aberrantly expressed in GC and affects the proliferation and migration of gastric cancer cells by acting as miRNA sponge.