Identification and Characterization of the Roles of circCASP9 in Gastric Cancer Based on a circRNA-miRNA-mRNA Regulatory Network

The study on circRNA profiling uncovers the regulatory function of the hsa_circ_0059665/miR-602 pathway in breast cancer

Abnormal expression of circRNAs has been observed in different types of carcinomas, and they play significant roles in the biology of these cancers. Nevertheless, the clinical relevance and functional mechanisms of the majority of circRNAs implicated in breast cancer progression remain unclear. The primary objective of our investigation is to uncover new circRNAs in breast cancer and elucidate the underlying mechanisms by which they exert their effects. The circRNA expression profile data for breast cancer and RNA-sequencing data were acquired from distinct public databases. Differentially expressed circRNAs and mRNA were identified through fold change filtering. The establishment of the competing endogenous RNAs (ceRNAs) network relied on the interplay between circular RNAs, miRNAs, and mRNAs. The hub genes were identified from the protein-protein interaction (PPI) regulatory network using the CytoHubba plugin in Cytoscape. Moreover, the expression levels and prognostic value of these hub genes in the PPI network were assessed using the GEPIA and Kaplan-Meier plotter databases. Fluorescence in situ hybridization (FISH) was used to identified the expression and intracellular localization of hsa_circ_0059665 by using the tissue microarray. Transwell analysis and CCK-8 analysis were performed to assess the invasion, migration, and proliferation abilities of breast cancer cells. Additionally, we investigated the interactions between hsa_circ_0059665 and miR-602 through various methods, including FISH, RNA-binding protein immunoprecipitation (RIP), and luciferase reporter assay. Rescue experiments were conducted to determine the potential regulatory role of hsa_circ_0059665 in breast cancer progression. A total of 252 differentially expressed circRNAs were identified. Among them, 246 circRNAs were up-regulated, while 6 circRNAs were down-regulated. Based on prediction and screening of circRNA-miRNA and miRNA-mRNA binding sites, we constructed a network consisting of circRNA-miRNA-mRNA interactions. In addition, we constructed a Protein-Protein Interaction (PPI) network and identified six hub genes. Moreover, the expression levels of these six hub genes in breast cancer tissues were found to be significantly lower. Furthermore, the survival analysis results revealed a significant correlation between low expression levels of KIT, FGF2, NTRK2, CAV1, LEP and poorer prognosis in breast cancer patients. The FISH experiment results indicated that hsa_circ_0059665 exhibits significant downregulation in breast cancer, and its decreased expression is linked to poor prognosis in breast cancer patients. Functional in vitro experiments revealed that overexpression of hsa_circ_0059665 can inhibit proliferation, migration and invasion abilities of breast cancer cells. Further molecular mechanism studies showed that hsa_circ_0059665 exerts its anticancer gene role by acting as a molecular sponge for miR-602. In our study, we constructed and analyzed a circRNA-related ceRNA regulatory network and found that hsa_circ_0059665 can act as a sponge for miR-602 and inhibit the proliferation, invasion and migration of breast cancer cells.

Helicobacter pylori upregulates circPGD and promotes development of gastric cancer

PURPOSE

Helicobacter pylori (H. pylori) has unique biochemical traits and pathogenic mechanisms, which make it a substantial cause of gastrointestinal cancers. Circular RNAs (circRNAs) have concurrently been identified as an important participating factor in the pathophysiology of several different cancers. However, the underlying processes and putative interactions between H. pylori and circRNAs have received very little attention. To address this issue, we explored the interaction between H. pylori and circRNAs to investigate how they might jointly contribute to the occurrence and development of gastric cancer.

METHODS

Changes in circPGD expression in H. pylori were detected using qRT-PCR. Cell proliferation and migration changes were assayed by colony formation, the CCK-8 assay and the transwell assay. Apoptosis was measured by flow cytometry. Western blot was conducted to detect changes in cell migration, apoptosis, proliferation and inflammation-associated proteins. QRT-PCR was used to measure changes in circPGD and inflammation-associated factors.

RESULTS

We found that H. pylori induced increased circPGD expression in infected human cells and facilitated gastric cancer progression in three ways by promoting cell proliferation and migration, enhancing the inflammatory response, and inhibiting apoptosis.

CONCLUSIONS

CircPGD appears to play a role in H. pylori-related gastric cancer and may thus be a viable, novel target for therapeutic intervention.

Circular RNA circTRPS1-2 inhibits the proliferation and migration of esophageal squamous cell carcinoma by reducing the production of ribosomes

Circular RNAs play important roles in many cancers, including esophageal squamous cell carcinoma (ESCC), but the precise functions of most circular RNAs are poorly understood. Here we detected significant downregulation of circTRPS1-2 in ESCC based on high-throughput sequencing of three pairs of ESCC tissue and adjacent normal tissue, followed by PCR validation with another 30 tissue pairs. Patients with ESCC whose circTRPS1-2 expression was below the median level for the sample showed significantly shorter median overall survival (13 months) than patients whose circTRPS1-2 expression was above the median (36 months). Overexpressing circTRPS1-2 in the human ESCC cell lines K150 and E109, which express low endogenous levels of circTRPS1-2, inhibited cell proliferation and migration. Conversely, knocking down circTRPS1-2 using short interfering RNA promoted cell proliferation and migration. Similar results were observed in mice bearing K150 xenografts in which circTRPS1-2 was overexpressed or knocked down. Several ribosomal proteins co-immunoprecipitated with circTRPS1-2 from K150 cells in culture, and K150 cells overexpressing circTRPS1-2 showed reduced numbers of ribosomes by A260 absorbance measure and electron microscopy. Our results suggest that circTRPS1-2 can inhibit ESCC proliferation and migration by reducing the production of ribosomes, establishing its potential usefulness in ESCC treatment and prediction of prognosis.

circ_0052184 Promotes Colorectal Cancer Progression via Targeting miR-604/HOXA9 Axis

Background

The mortality rate of colorectal cancer (CRC) ranks second. circRNAs are abnormal expression in some diseases, and their dysregulation is associated with cancer progression. Recent studies have shown that the malignant progression of colorectal cancer is inseparable from the abnormal expression of circRNAs.

Methods

First, the circ_0052184 expression in clinical tissue and cell samples was analyzed by qRT-PCR. Then, we constructed circ_0052184-silenced CRC cells and detected by qRT-PCR. Furthermore, the proliferation ability of cells was detected by colony formation assay. Cell migration ability was tested by wound healing assay and transwell assay. Cell invasion ability was detected by transwell assay.

Results

Expression of circ_0052184 was significantly increased in colorectal cancer cell lines and tissues. Silencing circ_0052184 affected the proliferation, migration, and invasion of colorectal cancer cells. miR-604 was targeted by circ_0052184. The downstream target of miR-604 was HOXA9, and silencing circ_0052184 inhibited HOXA9 expression. The existence of the circ_0052184/miR-604/HOXA9 regulatory network in colorectal cancer was validated. circ_0052184 promoted the occurrence and development of colorectal cancer by targeting the miR-604/HOXA9 axis.

Conclusions

Our study revealed that the molecular mechanism of circ_0052184 regulated the miR-604/HOXA9 axis, which might promote the malignant progression of colorectal cancer cells.