Silencing hsa_circRNA_0008035 exerted repressive function on osteosarcoma cell growth and migration by upregulating microRNA-375

Hsa_Circ_0008035 drives immune evasion of gastric cancer via promoting EXT1-mediated nuclear translocation of PKM2

Circular RNAs (circRNAs) have been reported to be associated with the malignant phenotypes of cancer. However, the role and underlying mechanism of hsa_Circ_0008035 in colorectal cancer (CRC) remains unclear. In this study, we elucidated the pivotal role of hsa_circ_0008035 in gastric cancer progression and immune evasion. Elevated hsa_circ_0008035 levels in gastric cancer patient serum correlated positively with disease advancement, including tumor stages and lymph node metastasis. Functional analyses revealed a negative association between hsa_circ_0008035 and CD8+ T cell number and function. Mechanistically, hsa_circ_0008035 encoded the novel protein EXT1-219aa, suppressing EXT1 phosphorylation and expression. Additionally, hsa_circ_0008035 regulated pyruvate metabolism by influencing the nucleus localization of PKM2. The identified EXT1/PKM2 axis further underscored the intricate regulatory mechanisms orchestrated by hsa_circ_0008035 in gastric cancer, offering potential diagnostic and therapeutic implications in the ongoing pursuit of targeted therapies for gastric cancer patients.

Circ_0008035 Promotes Gastric Cancer Development via the miR-429/SMAD2 Cascade

The vital roles of circular RNAs (circRNAs) in human tumorigenesis have attracted more attention. Circ_0008035 is one of the most up-regulated circRNAs in gastric cancer (GC). Herein, we explored the associated mechanism of circ_0008035 in GC. EdU incorporation experiments were performed to monitor cell proliferation ability. Cell cycle progression, apoptosis, angiogenesis, migration, and invasion were analyzed using flow cytometry, Tube formation, and Transwell assays respectively. Protein expression was detected by Western blot. Dual-luciferase reporter experiments were applied to demonstrate the relationship between circ_0008035 or SMAD family member 2 (SMAD2) and microRNA-429 (miR-429). Mouse xenograft assays were conducted for evaluation of the role of circ_0008035 in vivo. Circ_0008035 content was elevated in GC tissues (P < .0001) and cell lines (P < .001), and its deficiency hindered GC cell proliferation (P < .01), HUVEC angiogenesis (P < .05), and GC cell metastasis (P < .01) and triggered apoptosis (P < .01). Circ_0008035 could sponge miR-429 to up-regulate SMAD2 expression (P < .0001). Circ_0008035 absence restrained tumor growth in vivo (P < .01). MiR429 was a mediator of circ_0008035 function, and miR-429 hindered GC cell malignant phenotypes by SMAD2. Circ_0008035 aggravates GC cell malignant progression partially by targeting the miR-429/SMAD2 axis. Considering the inhibitory effect of circ_0008035 deficiency on GC progression, targeting circ_0008035 may be a potential approach to prevent or treat GC.

Research progress on the role of lncRNA, circular RNA, and microRNA networks in regulating ferroptosis in osteosarcoma

Noncoding RNAs (ncRNAs) do not participate in protein-coding. Ferroptosis is a newly discovered form of cell death mediated by reactive oxygen species and lipid peroxidation. Recent studies have shown that ncRNAs such as microRNAs, long noncoding RNAs, circular RNAs, and ferroptosis are involved in the occurrence and development of osteosarcoma (OS). Studies have confirmed that ncRNAs participate in the development of OS by regulating the ferroptosis. However, systematic summary on this topic are still lacking. This review summarises the potential role of ncRNAs in the diagnosis, treatment, drug resistance, and prognosis of OS and the basis for diagnosing, preventing, and treating clinical OS and developing effective drugs. This review summarises the latest research progress on ncRNAs that regulate ferroptosis in OS, attempts to clarify the molecular mechanisms by which ncRNAs regulate ferroptosis in the pathogenesis of OS, and elaborates on the involvement of ferroptosis in OS from the perspective of ncRNAs.

Circular RNA circBLNK promotes osteosarcoma progression and inhibits ferroptosis in osteosarcoma cells by sponging miR‑188‑3p and regulating GPX4 expression

As a newly identified circular RNA (circRNA), the role of circBLNK in cancer progression has not been probed. The objective of the present study was to functionally dissect the role of circBLNK in osteosarcoma (OS) tumorigenesis and progression. With regards of the experimental procedure, the levels of mRNAs and proteins were assessed using reverse transcription‑quantitative PCR and western blot analysis, respectively. The subcellular location of circBLNK in OS cells was determined by cell cytosolic/nuclear fractionation assay. Cell ferroptosis ability was assessed through MTT assay. Cell proliferative abilities were assessed by clonogenic and Cell Counting Kit‑8 assays, and cell apoptosis was measured using flow cytometry. The relationships among circBLNK, miR‑188‑3p, and glutathione peroxidase 4 (GPX4) were validated by luciferase reporter and RNA pull‑down assays, as well as RNA immunoprecipitation. The stability of circBLNK and linear BLNK was confirmed using RNase R treatment assay. The association between circBLNK expression and overall survival rate was assessed by Kaplan‑Meier plot. The correlation between the expression levels of circBLNK, miR‑188‑3p, and GPX4 in OS tissues was assessed by Pearson's χ2 test. The results revealed that CircBLNK and GPX4 were significantly upregulated in OS tissues, which predicted the poor prognosis. CircBLNK knockdown led to suppressed cell proliferation and enhanced cell apoptosis, an effect that could be reversed by the inhibition of miR‑188‑3p. In an in vivo circBLNK deficiency model, tumor growth was observed to be markedly suppressed. Moreover, circBLNK deficiency elevated levels of intracellular free iron (Fe2+), malondialdehyde, lipid reactive oxygen species and mitochondrial superoxide, while diminishing mitochondrial membrane potential in Erastin‑treated OS cells, which were eliminated by overexpressing GPX4. Furthermore, mechanistic investigations revealed that circBLNK sponged miR‑188‑3p to regulate the expression of GPX4, thereby affecting OS progression. In conclusion, the present study delineated a new regulatory axis involving circBLNK/miR‑188‑3p/GPX4 in OS progression, adding to the growing evidence that circRNAs are critical gene regulators in cancer progression.

CircPVT1 promotes the tumorigenesis and metastasis of osteosarcoma via mediation of miR-26b-5p/CCNB1 axis

INTRODUCTION

Osteosarcoma (OS) is the most aggressive malignancy among the bone tumors in the world. Circular RNAs (circRNAs) have been reported to be participated in multiple cancers, including OS. Meanwhile, circPVT1 has been proved to be upregulated in OS. However, the mechanism by which circPVT1 mediates the tumorigenesis of OS remains to be further explored.

MATERIALS AND METHODS

Protein and gene expressions in OS cells were measured by western blot and RT-qPCR, respectively. Cell growth was assessed by flow cytometry and colony formation, respectively. In addition, cell migration was assessed by wound healing, and invasion was evaluated by Transwell assay. Meanwhile, the correlation among circPVT1, miR-26b-5p and CCNB1 was explored by RNA pull-down and dual luciferase assay. Finally, in vivo model was established to explore the role of circPVT1 in OS in vivo.

RESULTS

CircPVT1 and CCNB1 were significantly upregulated in OS cells, while miR-26b-5p was downregulated. Knockdown of circPVT1 notably inhibited proliferation and induced apoptosis of OS cells. CircPVT1 shRNA significantly suppressed the OS cell invasion and migration. Meanwhile, circPVT1 sponged miR-26b-5p and CCNB1 was found to be the direct target of miR-26b-5p. Furthermore, silencing of circPVT1 inhibited the growth and metastasis of OS in vivo.

CONCLUSION

Silencing of circPVT1 notably suppressed the tumorigenesis and metastasis of OS via miR-26b-5p/CCNB1 axis. Therefore, circPVT1 might be used as a target for OS treatment.

Hsa_circ_0001017 promotes cell proliferation, migration and invasion in osteosarcoma by sponging miR-145-5p

BACKGROUND

Circular RNAs (circRNAs) have displayed important roles in the development and progression of various cancers. However, the functions of the majority of circRNAs in osteosarcoma (OS) remain unknown.

METHODS

Circular RNA microarray analysis was performed in three OS cell lines (Saos-2, U2OS and MG63) and normal vascular endothelial cells. The co-differentially expressed circRNAs (CDECs) were identified in OS cell lines with the criterion of FDR (false discovery rate) < 0.05 and |fold change (FC)|> 2. Quantitative real-time PCR was used to validate the expression levels of selected CDECs. A series of functional assays, including MTT assay, flow cytometry and transwell assay were conducted in OS cells. The interaction between circRNA and miRNAs was confirmed by luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

A total of 241 CDECs, including 75 upregulated and 166 downregulated CDECs, were identified in three OS cell lines compared with normal vascular endothelial cells. PCR validation showed that hsa_circ_0000704, hsa_circ_0001017 and hsa_circ_0005035 were all highly expression in the three OS cell lines, compared with osteoblast cell lines (HECC, hFOB1.19 and HFF-1). Functionally, overexpression of circ_0001017 significantly promoted the cell proliferation, migration and invasion and decreased apoptosis in U2OS cells. Knockdown of circ_0001017 obtained the opposite results. Circ_0001017 may downregulate miR-145-5p through direct binding. Furthermore, the expression of miR-145-5p was negatively regulated by circ_0001017 in OS cells. In addition, further functional studies indicated that miR-145-5p inhibitor eliminated the effects caused by si-circ_0001017 in OS cells.

CONCLUSIONS

In conclusion, our study suggested that circ_0001017 may be a novel oncogenic factor during the progression and development of OS by targeting miR-145-5p.