Circ-FOXM1 knockdown suppresses non-small cell lung cancer development by regulating the miR-149-5p/ATG5 axis

Circular RNAs (circRNAs) have been reported to be related to the development of human cancers. However, the function of circ-FOXM1 in non-small cell lung cancer (NSCLC) was largely unknown. Here, we revealed the role and functional mechanism of circ-FOXM1 in NSCLC progression. The relative expression of circ-FOXM1, microRNA-149-5p (miR-149-5p), and autophagy-related 5 (ATG5) was determined by quantitative real-time polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8), flow cytometry, and transwell assay were employed to assess cell viability, apoptosis, and migration, respectively. The relative protein expression was detected by western blot. Furthermore, mouse xenograft was carried out to analyze the effect of circ-FOXM1 on tumor growth in vivo. In addition, the interaction between miR-149-5p and circ-FOXM1 or ATG5 was predicted by Starbase3.0 and confirmed by the dual-luciferase reporter assay and RNA pull-down assay. Circ-FOXM1 and ATG5 levels were upregulated, while the miR-149-5p level was downregulated in NSCLC tissues and cells. Circ-FOXM1 knockdown suppressed NSCLC cell viability, migration, and autophagy, and induced cell apoptosis. Interestingly, circ-FOXM1 targeted miR-149-5p to upregulate the ATG5 level. Moreover, circ-FOXM1 exerted function through repressing miR-149-5p expression, and miR-149-5p exerted function via inhibiting ATG5 expression. Our results suggested that circ-FOXM1 knockdown attenuated the development of NSCLC through modulating the miR-149-5p/ATG5 axis, providing a theoretical basis for the therapy of NSCLC.

Circ-FOXM1 contributes to cell proliferation, invasion, and glycolysis and represses apoptosis in melanoma by regulating miR-143-3p/FLOT2 axis

Background

Numerous literatures have demonstrated that circular RNAs (circRNAs) are involved in multiple types of tumors. However, the effects of circRNAs in melanoma are not very clear. In this study, we aimed to investigate the roles and mechanisms of circ-FOXM1 in melanoma.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the expression of circ-FOXM1, microRNA-143-3p (miR-143-3p), and Flotillin 2 (FLOT2) mRNA. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, flow cytometry analysis, and transwell assay were employed to test cell proliferation, apoptosis, and invasion, respectively. The glucose consumption and lactate production were examined by specific kits. Western blot assay was utilized for the detection of hexokinase2 (HK2), pyruvate kinase isozyme type M2 (PKM2), and FLOT2. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were employed to verify the targeting association between miR-143-3p and circ-FOXM1 or FLOT2. A murine xenograft model was established to explore the effect of circ-FOXM1 in vivo.

Results

Circ-FOXM1 was elevated and miR-143-3p was reduced in melanoma tissues and cells. Circ-FOXM1 deficiency impeded cell proliferation, invasion, and glycolysis and facilitated cell apoptosis in melanoma in vitro and tumorigenesis in vivo. Circ-FOXM1 acted as a sponge of miR-143-3p and the impacts of circ-FOXM1 silencing on cell proliferation, apoptosis, invasion, and glycolysis were overturned by miR-143-3p deletion. Moreover, FLOT2 was a target gene of miR-143-3p and FLOT2 overexpression rescued the inhibitory effect of miR-143-3p on melanoma progression.

Conclusion

Circ-FOXM1 facilitated the development of melanoma by upregulating FLOT2 through miR-143-3p.

Circ-FOXM1 promotes the proliferation, migration and EMT process of osteosarcoma cells through FOXM1-mediated Wnt pathway activation

BACKGROUND

Osteosarcoma (OS) is a malignant bone tumor that commonly occurs in adolescents with a high mortality rate and frequent pulmonary metastasis. Emerging evidence has suggested that circular RNAs (circRNAs) are important regulators in multiple biological activities of carcinomas. Nevertheless, the role of circRNAs derived from forkhead box M1 (FOXM1), a well-accepted modulator of OS progression, has not been discussed in OS.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to test circ-FOXM1 (hsa_circ_0025033) expression in OS cell lines. Cell counting kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), transwell assays and western blot analysis of epithelial-mesenchymal transition (EMT) markers were conducted to evaluate cell proliferation, apoptosis, migration, and EMT process. Luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) assay were utilized to detect the interaction of circ-FOXM1 and RNAs.

RESULTS

High expression of circ-FOXM1 was detected in OS cell lines. Functionally, circ-FOXM1 knockdown inhibited the proliferation, migration and EMT process, whereas induced the apoptosis of OS cells. From the aspect of molecular mechanism, circ-FOXM1 was discovered to upregulate FOXM1 expression via sponging miR-320a and miR-320b, therefore activating Wnt signaling pathway. Besides, rescue experiments elucidated that circ-FOXM1 regulated cellular activities of OS cells via FOXM1. Further, in vivo assays supported that loss of circ-FOXM1 restrained OS tumor growth.

CONCLUSION

Circ-FOXM1 facilitated the malignant phenotypes of OS cells through FOXM1-mediated Wnt pathway activation, revealing circ-FOXM1 as a potential biomarker for OS treatment.