CircMYO10 promotes osteosarcoma progression by regulating miR-370-3p/RUVBL1 axis to enhance the transcriptional activity of β-catenin/LEF1 complex via effects on chromatin remodeling

Abstract

BackgroundCircMYO10 is a circular RNA generated by back-splicing of gene MYO10 and is upregulated in osteosarcoma cell lines, but its functional role in osteosarcoma is still unknown. This study aimed to clarify the mechanism of circMYO10 in osteosarcoma.MethodsCircMYO10 expression in 10 paired osteosarcoma and chondroma tissues was assessed by quantitative reverse transcription polymerase chain reaction (PCR). The function of circMYO10/miR-370-3p/RUVBL1 axis was assessed regarding two key characteristics: proliferation and endothelial–mesenchymal transition (EMT). Bioinformatics analysis, western blotting, real-time PCR, fluorescence in situ hybridization, immunoprecipitation, RNA pull-down assays, luciferase reporter assays, chromatin immunoprecipitation, and rescue experiments were used to evaluate the mechanism. Stably transfected MG63 cells were injected via tail vein or subcutaneously into nude mice to assess the role of circMYO10 in vivo.ResultsCircMYO10 was significantly upregulated, while miR-370-3p was downregulated, in osteosarcoma cell lines and human osteosarcoma samples. Silencing circMYO10 inhibited cell proliferation and EMT in vivo and in vitro. Mechanistic investigations revealed that miR-370-3p targets RUVBL1 directly, and inhibits the interaction between RUVBL1 and β-catenin/LEF1 complex while circMYO10 showed a contrary effect via the inhibition of miR-370-3p. RUVBL1 was found to be complexed with chromatin remodeling and histone-modifying factor TIP60, and lymphoid enhancer factor-1 (LEF1) to promote histone H4K16 acetylation (H4K16Ac) in the vicinity of the promoter region of gene C-myc. Chromatin immunoprecipitation methods showed that miR-370-3p sponge promotes H4K16Ac in the indicated region, which is partially abrogated by RUVBL1 small hairpin RNA (shRNA) while circMYO10 showed a contrary result via the inhibition of miR-370-3p. Either miR-370-3p sponge or ShRUVBL1 attenuated circMYO10-induced phenotypes in osteosarcoma cell lines. MiR-370-3p inhibition abrogated the inhibition of proliferation, EMT of osteosarcoma cells in vitro and in vivo seen upon circMYO10 suppression via Wnt/β-catenin signaling.ConclusionsCircMYO10 promotes osteosarcoma progression by regulating miR-370-3p/RUVBL1 axis to promote chromatin remodeling and thus enhances the transcriptional activity of β-catenin/LEF1 complex, which indicates that circMYO10 may be a potential therapeutic target for osteosarcoma treatment.

CircCDKN2B-AS1 Interacts with IMP3 to Stabilize Hexokinase 2 mRNA and Facilitate Cervical Squamous Cell Carcinoma Aerobic Glycolysis Progression

“…However, overexpression of circCDKN2B-AS1 lacking the binding site with IMP3 didn't have the above effects. Next, we showed that circCDKN2B-AS1 knockdown eliminated the glucose metabolism level of xenografted tumors veri ed by 18 FDG-PET/CT, and lowered the expression of both HK2 mRNA and HK2 protein of xenografted tumors.…”

“…Brie y, 4 tumor-bearing nude mice in each group were anesthetized by inhalation of iso urane gas (2-3%). Then the nude mice were injected with 7.4 MBq (200 µCi) of 18 F-FDG via the abdominal cavity and Scanned at 120 min after injection. Nude mice were subjected to a 10-min microCT scan and then to a 15-min microPET scan.…”

“…Another 4 pairs of tumor-bearing nude mice were scanned by 18 F-FDG microPET/CT imaging to assess the glucose metabolism level of xenografted tumors. And the Average SUV level in tumor tissues with circCDKN2B-AS1 knockdown was lower than that in control groups (Fig.…”

“…Recently, circRNAs are increasingly recognized as being implicated in gene regulatory networks and in uencing deseases [12,13]. The effect of circRNAs on the development in various cancers has been reported, such as breast cancer, oral cancer and hepatocellular carcinoma [14][15][16], Most of the discoveries revealed that circRNAs can function by sponging microRNAs and regulating the expression level of target genes [17][18]. Recent studies revealed that circRNAs can bind with RNA binding proteins (RBPs) [19][20][21], however, the potential value of circRNAs-RBP complex is still elusive and the biological function of most circRNAs in clinic is still unkonwn.…”

Emerging landscape of circular RNAs as biomarkers and pivotal regulators in osteosarcoma

“…As a novel circRNA generated by back‐splicing of MYO10, circMYO10 was found generally upregulated in osteosarcoma tissues comparing with paired chondroma (J. Chen, Liu, et al, 2019). Further functional investigations demonstrated that circMYO10 enhanced cell proliferation and EMT both in vitro and in vivo.…”