Next-generation sequencing reveals hsa_circ_0058092 being a potential oncogene candidate involved in gastric cancer

Emerging roles of circular RNAs in tumorigenesis, progression, and treatment of gastric cancer

With an estimated one million new cases reported annually, gastric cancer (GC) ranks as the fifth most diagnosed malignancy worldwide. The early detection of GC remains a major challenge, and the prognosis worsens either when patients develop resistance to chemotherapy or radiotherapy or when the cancer metastasizes. The precise pathogenesis underlying GC is not well understood, which further complicates its treatment. Circular RNAs (circRNAs), a recently discovered class of noncoding RNAs that originate from parental genes through "back-splicing", have been shown to play a key role in various biological processes in both eukaryotes and prokaryotes. CircRNAs have been linked to cardiovascular diseases, diabetes, hypertension, Alzheimer's disease, and the occurrence and progression of tumors. Prior studies have established that circRNAs play a crucial role in GC, impacting tumorigenesis, diagnosis, progression, and therapy resistance. This review aims to summarize how circRNAs contribute to GC tumorigenesis and progression, examine their roles in the development of drug resistance, discuss their potential as biotechnological drugs, and summarize their response to therapeutic drugs and microorganism in GC.

CircARID1A binds to IGF2BP3 in gastric cancer and promotes cancer proliferation by forming a circARID1A-IGF2BP3-SLC7A5 RNA–protein ternary complex

Background

Gastric cancer (GC) is one of the most common malignant tumors in China. Circular RNAs (circRNAs) are novel non-coding RNAs with important regulatory roles in cancer progression. IGF2BP3 has been found to play oncogenic roles in various cancers including GC, while the exact mechanism of IGF2BP3 is largely unknown.

Methods

The expression of IGF2BP3 in GC was evaluated by Western Blot and bioinformatics analysis. CircRNA expression profiles were screened via IGF2BP3 RIP-seq in GC. Sanger sequencing, RNase R digestion, nucleo-plasmic separation and RNA-FISH assays were used to detect the existence and expression of circARID1A. RNA ISH assay was employed to test the expression of circARID1A in paraffin-embedded GC tissues. Moreover, the function of circARID1A on cellular proliferation was assessed by CCK-8, plate colony formation, EdU assays and GC xenograft mouse model in vivo. Furthermore, the location or binding of circARID1A, IGF2BP3 protein and SLC7A5 in GC was evaluated by RNA-FISH/IF or RNA pull-down assays.

Results

We identified a novel circRNA, circARID1A, that can bind to IGF2BP3 protein. CircARID1A was significantly upregulated in GC tissues compared with noncancerous tissues and positively correlated with tumor length, tumor volume, and TNM stage. CircARID1A knockdown inhibited the proliferation of GC cells in vitro and in vivo and circARID1A played an important role in the oncogenic function of IGF2BP3. Mechanistically, circARID1A served as a scaffold to facilitate the interaction between IGF2BP3 and SLC7A5 mRNA, finally increasing SLC7A5 mRNA stability. Additionally, circARID1A was able to directly bind SLC7A5 mRNA through complementary base-pairing and then formed the circARID1A-IGF2BP3-SLC7A5 RNA–protein ternary complex and promoted the proliferation of GC via regulating AKT/mTOR pathway.

Conclusions

Altogether, our data suggest that circARID1A is involved in the function of IGF2BP3 and GC proliferation, and the circARID1A-IGF2BP3-SLC7A5 axis has the potential to serve as a novel therapeutic target for GC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02466-3.

Circular RNA circZCCHC6 contributes to tumorigenesis by regulating LPCAT1 via miR-433-3p in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-associated mortality worldwide. Circular RNA (circRNA) circZCCHC6 has been reported to be upregulated in the plasma from NSCLC patients. This study is designed to explore the role and mechanism of circZCCHC6 in NSCLC. CircZCCHC6, microRNA-433-3p (miR-433-3p), and lysophosphatidylcholine acyltransferase 1 (LPCAT1) level were determined by real-time quantitative polymerase chain reaction. Cell viability, cell cycle progression, migration, and invasion were assessed by 3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT), flow cytometry, wound healing, and transwell assays, severally. The binding relationship between miR-433-3p and circZCCHC6 or LPCAT1 was predicted by Circinteractome or Starbase, and then verified by a dual-luciferase reporter, RNA pull-down, or RNA Immunoprecipitation (RIP) assays. Protein levels of LPCAT1, Cyclin D1, E-cadherin, and Vimentin were examined by western blot assay. The biological role of circZCCHC6 on NSCLC tumor growth and epithelial-mesenchymal transition (EMT) was examined by the xenograft tumor model in vivo. CircZCCHC6 was highly expressed in NSCLC serum, tissues, and cells. Moreover, circZCCHC6 knockdown could repress cell viability, cell cycle progression, migration, invasion, and EMT in NSCLC cells in vitro. The mechanical analysis suggested that circZCCHC6 acted as a sponge of miR-433-3p to regulate LPCAT1 expression. CircZCCHC6 silencing hindered cell growth and EMT of NSCLC in vivo. CircZCCHC6 inhibited the progression of NSCLC cells partly by regulating the miR-433-3p/LPCAT1 axis, implying a promising therapeutic target for the NSCLC treatment.

Profiling Analysis of Circular RNA and mRNA in Human Temporal Lobe Epilepsy with Hippocampal Sclerosis ILAE Type 1

Hippocampal sclerosis (HS) is the most common surgical pathology associated with temporal lobe epilepsy (TLE). However, the cause of TLE with or without HS remains unknown. Our current study aimed to illustrate the essential molecular mechanism that is potentially involved in the pathogenesis of TLE-HS and to shed light on the transcriptional changes associated with hippocampal sclerosis. Compared to no-HS group, 341 mRNA transcripts and 131 circRNA transcripts were differentially expressed in ILAE type 1 group. The raw sequencing data have been deposited into sequence-read archive (SRA) database under accession number PRJNA699348.Gene Ontology analysis demonstrated that the dysregulated genes were associated with the biological processes of vesicle-mediated transport. Enrichment analysis demonstrated that dysregulated genes were involved mainly in the MAPK signal pathway. Subsequently, A total of 441 known or predicted interactions were formed among DEGs, and the most important module was detected in the PPI network using the MCODE plug-in. There were mainly four functional modules enriched: ER to Golgi transport vesicle membrane, Basal transcription factors, GABA-gated chloride ion channel activity, CENP-A containing nucleosome assembly. A circRNA-mRNA co-expression network was constructed including 5 circRNAs(hsa_circ_0025349, hsa_circ_0002405, hsa_circ_0004805, hsa_circ_0032254, and hsa_circ_0032875) and three mRNAs (FYN, SELENBP1, and GRIPAP1) based on the normalized mRNA signal intensities. This is the first to report the circRNAs and mRNAs expression profile of surgically resected hippocampal tissues from TLE patients of ILAE-1 and no-HS, and these results may provide new insight into the transcriptional changes associated with this pathology.

Circular RNAs and gastrointestinal cancers: Epigenetic regulators with a prognostic and therapeutic role

Both environmental and genetic factors are involved in the initiation and development of gastrointestinal cancer. Covalent closed circular RNAs (circRNAs) are produced by a mechanism called "back-splicing" from mRNAs. They are highly stable and show cell and tissue specific expression patterns. Although some functions such as "microRNA sponge" and "RNA binding protein sponge" have been reported for a small number of circRNAs, the function of thousands of other circRNAs is still unknown. Dysregulation of circRNAs has been reported in many GI cancers and are involved in metastasis and invasion. CircRNAs have been reported to be useful as prognostic markers and targets for developing new treatments. We first describe the properties and biogenesis of circRNAs. We then summarize recent reports about circRNA functions, expression status, and their potential to be used as biomarkers in GI cancers including, gastric cancer, colorectal cancer, esophageal cancer, hepatocellular carcinoma, gallbladder cancer and pancreatic cancer.