CircDENND2A Promotes Non-small Cell Lung Cancer Progression via Regulating MiR-34a/CCNE1 Signaling

Circular RNAs in Cell Cycle Regulation of Cancers

Cancer has been one of the most problematic health issues globally. Typically, all cancers share a common characteristic or cancer hallmark, such as sustaining cell proliferation, evading growth suppressors, and enabling replicative immortality. Indeed, cell cycle regulation in cancer is often found to be dysregulated, leading to an increase in aggressiveness. These dysregulations are partly due to the aberrant cellular signaling pathway. In recent years, circular RNAs (circRNAs) have been widely studied and classified as one of the regulators in various cancers. Numerous studies have reported that circRNAs antagonize or promote cancer progression through the modulation of cell cycle regulators or their associated signaling pathways, directly or indirectly. Mostly, circRNAs are known to act as microRNA (miRNA) sponges. However, they also hold additional mechanisms for regulating cellular activity, including protein binding, RNA-binding protein (RBP) recruitment, and protein translation. This review will discuss the current knowledge of how circRNAs regulate cell cycle-related proteins through the abovementioned mechanisms in different cancers.

CircWHSC1 serves as a prognostic biomarker and promotes malignant progression of non-small-cell lung cancer via miR-590-5p/SOX5 axis

Dysregulated circWHSC1 has been shown to play potential roles in diverse cancer types, including ovarian cancer, endometrial cancer and hepatocellular carcinoma (HCC). The objective of this study was to investigate its expression, underlying role and regulatory mechanism in non-small-cell lung cancer (NSCLC). The expression of circWHSC1 was determined by real-time PCR. After knockdown of circWHSC1 expression in NSCLC cells, the proliferation, migration, and invasion were detected using CCK-8, colony formation, and Transwell assays, and the effects of circWHSC1 on NSCLC tumorigenesis in vivo was also investigated. With the help of luciferase reporter and pull-down assays, we further explored the downstream mechanism of circWHSC1 in NSCLC cells. CircWHSC1 was highly expressed in NSCLC tissues and cell lines. The inhibition of circWHSC1 suppressed the malignant properties of NSCLC cells, as evidenced by the reduction of proliferation, migration and invasion. CircWHSC1 sponged miR-590-5p and functioned as an oncogene in NSCLC by increasing sex determining region Y-boxprotein 5 (SOX5) expression. CircWHSC1 may contribute to the oncogenicity of NSCLC via the regulation of miR-590-5p/SOX5 axis, which might be a novel therapeutic target in NSCLC.

Effect of CDK7 inhibitor on MYCN-amplified retinoblastoma

Retinoblastoma (RB) is a common malignancy that primarily affects pediatric populations. Although a well-known cause of RB is RB1 mutation, MYCN amplification can also lead to the disease, which is a poor prognosis factor. Studies conducted in various tumor types have shown that MYCN inhibition is an effective approach to impede tumor growth. Various indirect approaches have been developed to overcome the difficulty of directly targeting MYCN, such as modulating the super enhancer (SE) upstream of MYCN. The drug used in this study to treat MYCN-amplified RB was THZ1, a CDK7 inhibitor that can effectively suppress transcription by interfering with the activity of SEs. The study findings confirmed the anticancer activity of THZ1 against RB in both in vitro and in vivo experiments. Therapy with THZ1 was found to affect numerous genes in RB according to the RNA-seq analysis. Moreover, the gene expression changes induced by THZ1 treatment were enriched in ribosome, endocytosis, cell cycle, apoptosis, etc. Furthermore, the combined analysis of ChIP-Seq and RNA-seq data suggested a potential role of SEs in regulating the expression of critical transcription factors, such as MYCN, OTX2, and SOX4. Moreover, ChIP-qPCR experiments were conducted to confirm the interaction between MYCN and SEs. In conclusion, THZ1 caused substantial changes in gene transcription in RB, resulting in inhibited cell proliferation, interference with the cell cycle, and increased apoptosis. The efficacy of THZ1 is positively correlated with the degree of MYCN amplification and is likely exerted by interfering with MYCN upstream SEs.

Circular RNA Controls Tumor Occurrence and Development via Cell Cycle Regulation

Circular RNAs (circRNAs) participate in the occurrence and development of various diseases through different mechanisms, such as by acting as a microRNA (miRNA) sponge, interacting with RNA-binding proteins, and regulating gene transcription and protein translation. For example, the abnormal expression of specific circRNAs in tumor cells can alter key regulatory factors and the cell cycle network, resulting in cell cycle disorders and the development and metastasis of tumors. Here, we summarize the mechanisms involved in the circRNA-mediated processes that lead to uncontrolled cell cycle and tumor cell proliferation. Extensive studies investigating the abnormal expression of circRNAs in different cancer types have been conducted. The unique characteristics of circRNAs and their ability to regulate the cell cycle through diverse mechanisms is extremely valuable in tumor diagnosis, treatment, and prognosis. Our review may assist in further understanding the circRNA-mediated regulation of the cell cycle in tumors and provide insights for research on circRNA-based therapeutic strategies and biological diagnosis for cancer.

USP15 negatively regulates lung cancer progression through the TRAF6-BECN1 signaling axis for autophagy induction

TNF receptor-associated factor 6 (TRAF6)-BECN1 signaling axis plays a pivotal role in autophagy induction through ubiquitination of BECN1, thereby inducing lung cancer migration and invasion in response to toll-like receptor 4 (TLR4) stimulation. Herein, we provide novel molecular and cellular mechanisms involved in the negative effect of ubiquitin-specific peptidase 15 (USP15) on lung cancer progression. Clinical data of the TCGA and primary non-small cell lung cancer (NSCLC) patients (n = 41) revealed that the expression of USP15 was significantly downregulated in lung cancer patients. Importantly, USP15-knockout (USP15KO) A549 and USP15KO H1299 lung cancer cells generated with CRISPR-Cas9 gene-editing technology showed increases in cancer migration and invasion with enhanced autophagy induction in response to TLR4 stimulation. In addition, biochemical studies revealed that USP15 interacted with BECN1, but not with TRAF6, and induced deubiquitination of BECN1, thereby attenuating autophagy induction. Notably, in primary NSCLC patients (n = 4) with low expression of USP15, 10 genes (CCNE1, MMP9, SFN, UBE2C, CCR2, FAM83A, ETV4, MYO7A, MMP11, and GSDMB) known to promote lung cancer progression were significantly upregulated, whereas 10 tumor suppressor genes (FMO2, ZBTB16, FCN3, TCF21, SFTPA1B, HPGD, SOSTDC1, TMEM100, GDF10, and WIF1) were downregulated, providing clinical relevance of the functional role of USP15 in lung cancer progression. Taken together, our data demonstrate that USP15 can negatively regulate the TRAF6-BECN1 signaling axis for autophagy induction. Thus, USP15 is implicated in lung cancer progression.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

Bioinformatics Analysis Reveals the Related Role of miR-511-5p in the Progression of Breast Cancer

Breast cancer remains a dangerous disease, and delving the molecular mechanism of breast cancer is still necessary. To illustrate the role of miR-511-5p, TCGA database was used to excavate the abundance of miR-511-5p, and the miR-511-5p level was measured in the pathological tissues and tumor cell lines. Moreover, the targets of miR-511-5p were identified with miRDIP and GEPIA and then were used for functional enrichment analysis. Besides, the targets of miR-511-5p were analyzed with the protein-protein interaction (PPI) network for the hub nodes, and then the expression levels of the hub nodes were visualized with the GEPIA database. The results showed that miR-511-5p was significantly downregulated in multiple types of tumor samples in the online database, and the downregulated miR-511-5p was also found in pathological tissues and tumor cell lines. Moreover, 48 genes were identified as the potential targets of miR-511-5p by miRDIP and GEPIA databases and enriched in cell cycle, PI3K/AKT, and P53 pathways. Besides, seven genes including BRCA1, FN1, CCNE1, CCND1, CHEK1, BUB3, and CDC25A were identified as the hub nodes by the PPI network, and CCNE1 and CHEK1 were confirmed to be related with the prognostic survival of the patients with breast cancer. In conclusion, the proofs in this study suggest that reduced miR-511-5p was a biomarker event for breast cancer, and CCNE1 and CHEK1 served as potential targets of miR-511-5p to involve the progression of breast cancer.

Multiple bronchiolar adenomas with malignant transformation and CCNE1 mutation: a case report and literature review

BACKGROUND

Bronchiolar adenoma (BA) is a recently proposed diagnostic terminology, which is considered as the expansion of the concept of ciliated muconodular papillary tumors. BA is considered to be a benign neoplasm, but a few previous cases have been reported with the possibility of malignant transformation. Therefore, the genetic and histological nature of BA is controversial so far. We describe a rare case of multiple BAs with malignant transformation and CCNE1 (cyclin E1) mutation to increase the understanding of this disease.

CASE DESCRIPTION

A 56-year-old woman was admitted to our hospital due to two ground-glass nodules (GGNs) in the left lung detected by chest CT without symptom. The pure GGN located in the upper lingual segment about 6 mm in diameter and another mixed GGN located in the dorsal segment about 7 mm. The two GGNs have been found a year ago without treatment, and the mixed GGN become larger to 8 mm with vacuole sign in the next year health checkup. We performed a wedge resection of the two nodules completely by video-assisted thoracoscopy (VATS). Postoperative pathology indicated that the pure GGN was atypical bronchial adenoma, while the mixed GGN was atypical bronchial adenoma with malignant transformation which was missed in frozen section. Gene mutations analysis by next-generation sequencing (NGS) showed CCNE1 gene mutation in both lesions, and her-2 mutation was identified in the mixed GGN. The programmed cell death 1 ligand 1 (PD-L1) expression analysis of tumor cells showed 0% and less than 1% in the pure GGN and the mixed GGN, respectively.

CONCLUSION

BA is generally considered to be a benign tumor. The present study indicated that BA may be carcinogenic in atypical cases with some driver genes mutation and we should be vigilant for its potentiality of malignant transformation in clinical practice.

Biogenesis, Functions, and Role of CircRNAs in Lung Cancer

CircRNAs, a class of endogenous non-coding RNAs with closed-loop structures, have attracted increasing attention because of their good stability, high specificity of tissue expression, long half-life, and highly conserved sequence. CircRNAs have multiple biological functions, including miRNA sponge, transcription regulator, protein translation, interaction with protein, RNA maturation, and so on. These functions indicate the important role of circRNAs in tumorigenesis and malignant progression and their potential as potent diagnostic biomarkers and therapeutic molecules. In recent years, an increasing body of evidence suggests that circRNAs play a crucial role in proliferation, migration, invasion, and apoptosis of lung cancer cells. Therefore, circRNAs have gradually become a research focus in the diagnosis and treatment of lung cancer patients. This review summarizes the classification, biogenesis, and function of circRNAs, and discusses the role of circRNAs in the diagnosis, prognosis, and treatment of lung cancer patients.

A Novel circRNA-miRNA-mRNA Hub Regulatory Network in Lung Adenocarcinoma

The growing evidence suggests that circular RNAs (circRNAs) have significant associations with tumor occurrence and progression, yet the regulatory mechanism of circRNAs in lung adenocarcinoma (LUAD) remains unclear. This study clarified the potentially regulatory network and functional mechanism of circRNAs in LUAD. The expression data of circRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) were obtained from the Gene Expression Omnibus (GEO) database. Relying on GSE101586, GSE101684, and GSE112214, we identified differentially expressed circRNAs (DEcircRNAs). Depending on GSE135918 and GSE32863, we screened out differentially expressed miRNAs (DEmiRNAs) and mRNAs (DEmRNAs), respectively. Then, a novel competing endogenous RNA (ceRNA) regulatory network related to LUAD was constructed. We also revealed biological processes and signal pathways regulated by these DEcircRNAs. Based on gene expression data and survival information of LUAD patients in The Cancer Genome Atlas (TCGA) and GEO, we implemented survival analysis to select DEmRNAs related to prognosis and build a novel circRNA-miRNA-mRNA hub regulatory network. Meanwhile, quantitative real-time PCR (qRT-PCR) was utilized to validate DEcircRNAs in the ceRNA hub regulatory network. As a result, a total of 8 DEcircRNAs, 19 DEmiRNAs, and 85 DEmRNAs were identified. The novel ceRNA regulatory network included 5 circRNAs, 8 miRNAs, and 22 mRNAs. The final ceRNA hub regulatory network contained two circRNAs, two miRNAs, and two mRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that the five DEcircRNAs may affect LUAD onset and progression through Wnt signaling pathway and Hippo signaling pathway. All in all, this study revealed the regulatory network and functional mechanism of circRNA-related ceRNAs in LUAD.

Long Non-coding RNA SENP3-EIF4A1 Functions as a Sponge of miR-195-5p to Drive Triple-Negative Breast Cancer Progress by Overexpressing CCNE1

Triple-negative breast cancer (TNBC) has high malignancy and limited treatment, so novel molecular therapeutic targets are urgently needed. Cyclin E1 (CCNE1) promotes progression in breast cancer, but its role and inherent mechanisms in TNBC are yet to be elucidated. Competing endogenous RNA (ceRNA) may be a potential mechanism. CCNE1 was selected though bioinformatics and clinical samples, and cell lines were utilized to verify CCNE1 expression by qRT-PCR and western blot. Predicting tools provided potential miR-195-5p and SENP3-EIF4A1 and tested from multilevel. Functional experiments were conducted in vitro and in vivo. Luciferase reporter assay and RNA immunoprecipitation experiments were implemented to ensure the interaction between miR-195-5p and SENP3-EIF4A1/CCNE1 in TNBC. Bioinformatics found DNA hypermethylation of miR-195-5p and preliminarily verified. Mechanistically, SENP3-EIF4A1-miR-195-5p-associated ceRNA could drive TNBC progress though regulating CCNE1. DNA hypermethylation of miR-195-5p might be another reason. In summary, SENP3-EIF4A1-miR-195-5p-CCNE1 axis promotes TNBC progress and may contribute to the novel diagnosis and treatment of TNBC.