Circular RNAs are differentially expressed in liver ischemia/reperfusion injury model

Circular RNA circRHOBTB3 inhibits ovarian cancer progression through PI3K/AKT signaling pathway

BACKGROUND

Circular RNAs (circRNAs) have emerged as significant regulators in human cancers. We aimed to explore the functional role of circular RNA RHOBTB3 (circRHOBTB3) in ovarian cancer.

METHODS

The expression of circRHOBTB3 was detected by real-time quantitative PCR (RT-qPCR). Then, the localization of circRHOBTB3 in ovarian cancer cells was identified by cell fractionation assay. Cell proliferation, migration and invasion were measured by cell counting kit-8 (CCK-8), transwell migration and invasion assays, respectively. The protein expression of N-cadherin, vimentin and E-cadherin was measured by western blot. And the glucose consumption and lactate production were detected by a glucose colorimetric assay kit and a lactic acid production detection kit, respectively. The involvement mRNA and protein expression of glucose transporter 1 (GLUT1), hexokinase-2 (HK2) and lactate dehydrogenase A (LDHA) were determined by RT-qPCR and western blot, respectively. Besides, lentivectors for short hairpin RNA (shRNA) against circRHOBTB3 (sh-circRHOBTB3) or pcDNA-circRHOBTB3 were used to downregulate or upregulate circRHOBTB3 expression in an animal tumor model. The protein expression of phosphoinositide 3-kinase (PI3K), phospho-PI3K (p-PI3K), protein kinase B (AKT), phospho-AKT (p-AKT), mammalian target of rapamycin (mTOR) and phospho-mTOR (p-mTOR) was examined by western blot. The activator (740Y-P) and inhibitor (LY294002) of PI3K/AKT pathway were used to evaluate the contribution of PI3K/AKT. CircRHOBTB3 was downregulated in ovarian cancer tissues and cells.

RESULTS

Functionally, circRHOBTB3 overexpression could markedly suppress cell proliferation, metastasis, and glycolysis, whereas the opposite results could be observed in the deletion of circRHOBTB3. Additionally, xenograft experiment also identified the above results. Finally, we observed that circRHOBTB3 inhibited the progression of ovarian cancer via inactivating PI3K/AKT signaling pathway.

CONCLUSIONS

CircRHOBTB3 exerted a suppressor role and inhibited the tumorigenesis by inactivating PI3K/AKT pathway in ovarian cancer.

The effect of Moringa oleifera crude extract on liver cell line, HepG2

BACKGROUND

The liver plays a crucial role in the body's metabolic and detoxification processes. Given its importance, compromised liver function can negatively impact the body's metabolic and physiological function. Liver diseases can result from several factors, including exposure to toxins, alcohol consumption, and viral infections. Therefore, finding natural remedies for liver protection and treatment is important. Moringa oleifera is a tree known for its various medicinal properties, including hepatoprotective effects. This study aimed to investigate the potential of M. oleifera seed extract in protecting liver cells.

METHODS

In this study, dried-seed powder of M. oleifera was extracted using extraction solvents, methanol, and ethanol. HepG2 cells were cultured and treated with different concentrations of the extracts. The antioxidative activity, cell viability, and antiproliferation were assessed using the total antioxidant capacity assay (TAC) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Additionally, liver enzyme activity was determined through alkaline phosphatase and aspartate aminotransferase activity assays.

RESULTS

The extracts had varying effects on liver cells depending on the concentration and time of exposure. Lower concentrations (50 mg/l and 100 mg/l) have mild stimulatory effects/minimal impact on metabolic activity, while higher concentrations (200 mg/l and 400 mg/l) tend to decrease metabolic activity, especially at later time points. Moreover, the extracts effectively reduced the levels of the liver enzyme AST, indicating their ability to mitigate liver injury.

CONCLUSION

The study concludes that the crude extracts of M. oleifera seeds exhibit potential as a natural remedy for liver diseases. The effects of M. oleifera extract suggest that it has potential as a preventive and therapeutic agent for liver damage. This study highlights the importance of exploring natural remedies for liver protection and treatment.

Berberine protects hepatocyte from hypoxia/reoxygenation-induced injury through inhibiting circDNTTIP2

Background

During hepatic ischemia-reperfusion injury, the excessive release of inflammatory cytokines can activate the intracellular signal transduction cascade to induce hepatocyte injury. Apoptosis is an important way of cell death after I/R injury. Berberine, a common quaternary ammonium alkaloid, has anti-inflammatory, anti-oxidative stress, and anti-apoptotic effects. An increasing number of studies have revealed the importance of non-coding RNAs, including microRNA, long non-coding RNAs and circular RNAs (circRNAs), as regulators of the effects of berberine.

Purpose

In this study, we investigated the mechanism of berberine against liver ischemia-reperfusion injury in vitro.

Study Design and Methods

In this study, hypoxia-reoxygenation (H/R)-treated L02 cells were pretreated with berberine to study the role and mechanism of berberine in resisting hepatic ischemia-reperfusion injury.

Results

The results show that berberine pre-treatment increased the cell viability of H/R-challenged cells, reduced H/R-induced apoptosis and ROS production, reversed H/R-increased on IL-6, IL-1β, TNF-α, and H/R-decreased IL-10 expression. Mechanically, berberine protect hepatocyte from H/R injury, at least partially, through circDNTTIP2. In addition, circDNTTIP2 can bind to the TATA box of caspase3 promoter, thereby promoting caspase 3-related cell apoptosis and the release of inflammatory cytokines.

Conclusion

This study found that berberine has a protective effect on H/R-induced hepatocyte damage by inhibiting a novel circRNA, circDNTTIP2. This study provides potential treatment strategies and treatment targets for liver ischemia-reperfusion injury.

Identification of circular RNA biomarkers for Pien Tze Huang treatment of CCl4‑induced liver fibrosis using RNA‑sequencing

Pien Tze Huang (PZH), a common hepatoprotective Traditional Chinese Medicine that has been found to be an effective treatment for carbon tetrachloride-induced hepatic damage, including liver fibrosis. Circular RNAs (circRNAs) serve a crucial role in regulating gene expression levels via circRNA/micro (mi)RNA/mRNA networks in several human diseases and biological processes. However, whether circRNAs are involved in the underlying mechanism of the therapeutic effects of PZH on liver fibrosis remains unclear. Therefore, the aim of the present study was to investigate these effects using circRNA expression profiles from PZH-treated fibrotic livers in model mice. A case-control study on >59,476 circRNAs from CCl₄-induced (control group, n=6) and PZH-treated (case group, n=6) mice was performed using circRNA sequencing in liver tissues. PZH treatment resulted in the differential expression of 91 circRNAs, including 58 upregulated and 33 downregulated circRNAs. Furthermore, the construction of competing endogenous networks also indicated that differentially expressed circRNAs acted as miRNA sponges. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of miRNA targets demonstrated that PZH-affected circRNAs were mainly involved in biological processes such as ‘positive regulation of fibroblast proliferation’, ‘cellular response to interleukin-1’ and ‘regulation of DNA-templated transcription in response to stress’ and in a number of important pathways, such as ‘TNF signaling pathway’, ‘PI3K-Akt signaling pathway’, ‘IL-17 signaling pathway’ and ‘MAPK signaling pathway’. To further validate the bioinformatics data, reverse transcription–quantitative PCR was performed on seven miRNA targets in a human hepatic stellate LX-2 cell model. The results suggested that seven of the miRNAs exhibited regulatory patterns that were consistent with those of the transcriptome sequencing results. Kaplan-Meier survival analysis demonstrated that the expression levels of dihydrodiol dehydrogenase and solute carrier family 7, member 11 gene were significantly associated with patient survival, 269 patients with liver hepatocellular carcinoma from The Cancer Genome Atlas database. To the best of our knowledge, this was the first study to provide evidence that PZH affects circRNA expression levels, which may serve important roles in PZH-treated fibrotic liver through the regulation of functional gene expression. In conclusion, the present study provided new insights into the mechanism underlying the pathogenesis of liver fibrosis and identified potential novel, efficient, therapeutic targets against liver injury.

Circular RNA as An Epigenetic Regulator in Chronic Liver Diseases

Circular RNA (circRNA) is a type of non-coding RNA characterized by a covalently closed continuous loop. CircRNA is generated by pre-mRNA through back-splicing and is probably cleared up by extracellular vesicles. CircRNAs play a pivotal role in the epigenetic regulation of gene expression at transcriptional and post-transcriptional levels. Recently, circRNAs have been demonstrated to be involved in the regulation of liver homeostasis and diseases. However, the epigenetic role and underlying mechanisms of circRNAs in chronic liver diseases remain unclear. This review discussed the role of circRNAs in non-neoplastic chronic liver diseases, including alcoholic liver disease (ALD), metabolic-associated fatty liver disease (MAFLD), viral hepatitis, liver injury and regeneration, liver cirrhosis, and autoimmune liver disease. The review also highlighted that further efforts are urgently needed to develop circRNAs as novel diagnostics and therapeutics for chronic liver diseases.

Circular RNA Microarray Analyses in Hepatic Ischemia-Reperfusion Injury With Ischemic Preconditioning Prevention

Ischemic preconditioning (IPC) represents an effective intervention to relieve hepatic ischemia-reperfusion injury (IRI). Systematic detection of circRNA expression revealing the protection effect of IPC still remains to be elucidated. Here, we applied a microarray to detect circRNA and mRNA expression in ischemic liver with and without IPC (n = 3 in each group). Compared with the sham group, there were 39 circRNAs and 432 mRNAs increased and 38 circRNAs and 254 mRNAs decreased (fold change ≥1.5, P < 0.05) in the group of hepatic IRI. As the result of IPC intervention, 43 circRNAs and 64 mRNAs were increased, and 7 circRNAs and 31 mRNAs were decreased in the IPC group when compared with IRI. We then identified circRNA_017753 as the most possible target that may closely relate to IPC protective signaling and predicted Jade1 as the target related to circRNA_017753. Three possible circRNA-miRNA-mRNA axes were constructed that may play a vital role in protective mechanisms in IPC. The study for the first time systematically detects the dysregulated circRNAs and mRNAs in response to hepatic IRI and IPC intervention. Our profile and bioinformatic analysis provide numerous novel clues to understanding the pathophysiologic mechanism of IPC protection against hepatic IRI.

Comprehensive analysis of circular RNAs from steatotic livers after ischemia and reperfusion injury by next-generation RNA sequencing

Global organ shortage has led to the acceptance of steatotic livers for transplantation, taking the risk of graft dysfunction associated with the higher sensitivity of steatotic livers to ischemia and reperfusion injury (IRI). Data about circular RNAs (circRNAs) in steatotic livers following IRI are practically nonexistent. In our study, a high-fat diet-fed mouse model of hepatic steatosis was generated, and RNA sequencing was performed both on IRI and on sham liver tissues of these mice to screen for circRNAs with significant differential expression. To further validate our bioinformatics data, one upregulated circRNA and four downregulated circRNAs were examined. The circularity of these circRNAs was demonstrated using RNaseR digestion and Sanger sequencing. The expression of four stable circRNAs undigested by RNaseR was further validated by quantitative PCR. In summary, this study unearths several circRNAs as novel and potentially effective targets involved in the more severe damage of steatotic livers following IRI.

Microarray Analysis For Expression Profiles of lncRNAs and circRNAs in Rat Liver after Brain-Dead Donor Liver Transplantation

The mechanisms underlying severe liver injury after brain-dead (BD) donor liver transplantation (BDDLT) remain unclear. In this study, we aimed to explore the roles of lncRNAs and circRNAs in liver injury after BDDLT. Rat liver injury was detected in the sham, BD, control, and BDDLT groups. We examined the expression profiles of lncRNAs and circRNAs in the livers of the BDDLT and control group using microarray analysis. The main functions of the differentially expressed genes were analyzed by gene ontology (GO) and KEGG pathway enrichment analysis. In addition, we used bioinformatic analyses to construct related expression networks. Liver injury was aggravated in the BD and BDDLT groups. We found various mRNAs, lncRNAs, and circRNAs that were differentially expressed in the BDDLT group compared with those in the control group. Coding-noncoding gene co-expression (CNC) network analysis showed that expression of the lncRNA LOC102553657 was associated with that of the apoptosis-related genes including HMOX1 and ATF3. Furthermore, competing endogenous RNAs (ceRNAs) network analysis revealed that the lncRNA LOC103692832 and rno_circRNA_007609 were ceRNAs of rno-miR-135a-5p targeting Atf3, Per2, and Mras. These results suggest that lncRNAs and circRNAs play important roles in the pathogenesis and development of liver injury during BDDLT.

The emerging importance of noncoding RNAs in the insecticide tolerance, with special emphasis on Plutella xylostella (Lepidoptera: Plutellidae)

Recently generated high-throughput sequencing data sets have shed light on the important regulatory roles of noncoding RNA (ncRNA) molecules in the development of higher organisms. Nowadays it is well-known that regulatory ncRNAs can bind complementary RNA or DNA sequences and recruit chromatin remodelers to selectively modulate gene expression. Consequently, genome sequencing and transcriptomics technologies are now being used to reveal hidden associations among ncRNAs and distinct biological mechanisms. This is the case for the diamondback moth Plutella xylostella, a worldwide pest known to infest cruciferous crops and to display resistance to most insecticides, including Bacillus thuringiensis (Bt) based biopesticides. In P. xylostella, it is thought that ncRNAs could play important roles in both development and insecticide resistance. This review will highlight recent insights into the roles of ncRNAs in P. xylostella and related lepidopterans, and will outline genetic engineering technologies which might be used to design efficient ncRNA-based pest control strategies. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

Overexpression of hsa_circ_0007534 predicts unfavorable prognosis for osteosarcoma and regulates cell growth and apoptosis by affecting AKT/GSK-3β signaling pathway

Accumulating evidence demonstrated the pivotal roles of circular RNAs (circRNAs) in several types of cancers. However, the study relevant to the biological functions of circRNAs in osteosarcoma (OS) is still very limited. Recently, hsa_circ_0007534 has been proved to play key roles in colorectal carcinoma and glioma. In this study, qRT-PCR was used to determine hsa_circ_0007534 expression in OS tissues and cells. The clinical value of hsa_circ_0007534 was further explored. Additionally, cell growth, clone formation ability and cell apoptosis were assessed after hsa_circ_0007534 silenced. The xenograft study was further induced to investigate the roles of hsa_circ_0007534 in vivo. Moreover, AKT/GSK-3β pathway was measured to illustrate the mechanism of hsa_circ_0007534 exerts in OS progression. The data demonstrated that hsa_circ_0007534 is overexpressed in OS tissue samples and cells and this up-regulation is related with larger tumor size and poorer differentiation degree. Moreover, hsa_circ_0007534 is a dismal prognostic biomarker for OS patients. For the functional assays, knockdown of hsa_circ_0007534 suppresses OS cell growth in vitro and in vivo. In addition, hsa_circ_0007534 protects against cell apoptosis via Bcl-2/caspase-3 pathway. Furthermore, AKT/GSK-3β pathway could be activated by hsa_circ_0007534 to facilitate OS progression. In summary, hsa_circ_0007534 may be a rational predictive marker and therapeutic target for OS.