RESUMO
Accumulating evidence suggests that developmental chemoresistance in cancers is closely associated with the dysregulation of circular RNA transcriptions. The objective of this study is to disclose the role of circ_0001667 and provide a potential functional mechanism in breast cancer. Quantitative real-time PCR was applied for the analysis of circ_0001667, microRNA-4458 (miR-4458) and nuclear receptor coactivator 3 (NCOA3) expression. In adriamycin (ADM)-resistant cell lines, we investigated cell proliferation using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and colony formation assay. Cell migration and cell invasion were determined by transwell assay. The protein levels of multi-drug resistance-1, matrix metalloproteinases-9, cleaved-caspase3, cleaved-caspase9 and NCOA3 were detected by western blot. ADM resistance was ascertained by IC50 value using MTT assay. Cell apoptosis was checked by flow cytometry assay. The putative relationship between miR-4458 and circ_0001667 and NCOA3 was validated by pull-down assay, dual-luciferase reporter assay or RNA Immunoprecipitation assay. Circ_0001667 knockdown inhibited MCF-7/ADM and MDA-MB-231/ADM cell proliferation, migration, invasion and ADM resistance. MiR-4458 was a target of circ_0001667, and its expression was decreased in ADM-resistant tumor tissues and cells. MiR-4458 inhibition reversed the effects of circ_0001667 knockdown. In depth, NCOA3 was a target of circ_0001667, and circ_0001667 knockdown weakened NCOA3 expression by releasing miR-4458. MCF-7/ADM and MDA-MB-231/ADM cell proliferation, migration, invasion, and ADM resistance inhibited by miR-4458 restoration were recovered by NCOA3 overexpression. Circ_0001667 knockdown also repressed tumor growth and ADM resistance in vivo. Circ_0001667 knockdown blocks cancer progression and attenuates ADM resistance by depleting NCOA3 via releasing miR-4458 in breast cancer.
Assuntos
Neoplasias da Mama , MicroRNAs , RNA Circular/genética , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Proliferação de Células , Doxorrubicina/farmacologia , Feminino , Humanos , Camundongos , Camundongos Nus , MicroRNAs/metabolismo , Coativador 3 de Receptor Nuclear/genética , Coativador 3 de Receptor Nuclear/metabolismoRESUMO
BACKGROUND: Circ_0072995 is a novel identified circRNA and has been identified to involve in the metastasis of breast cancer. However, the detailed function and mechanism of circ_0072995 in the biological property of breast cancer cell remain vague. MATERIALS AND METHODS: The expression of circ_0072995, microRNA (miR)-149-5p and serine hydroxymethyltransferase 2 (SHMT2) mRNA was detected using quantitative real-time polymerase chain reaction. Western blot was used to detect the protein levels of SHMT2, hexokinase-2 (HK-2), lactate dehydrogenase a chain (LDHA), and glucose transporter 1 (GLUT1). Cell proliferation, apoptosis, migration, and invasion were analyzed using cell counting kit-8 assay, flow cytometry, caspase-3 activity analysis, cell adhesion assay and transwell assay, respectively. Glucose metabolism was calculated by measuring glucose uptake, lactate production, and adenosine triphosphate (ATP) levels. The interaction between miR-149-5p and circ_0072995 or SHMT2 was confirmed by dual-luciferase reporter assay. In vivo tumorigenesis was performed using the murine xenograft model. RESULTS: Circ_0072995 and SHMT2 were up-regulated in breast cancer tissues and cell lines, and knockdown of circ_0072995 or SHMT2 suppressed cell malignant properties and anaerobic glycolysis; importantly, SHMT2 overexpression attenuated the anticancer action of circ_0072995 knockdown in breast cancer. Besides, we also found circ_0072995 directly targeted miR-149-5p, thereby regulating its downstream gene SHMT2 by competitively binding to miR-149-5p. Additionally, xenograft analysis showed circ_0072995 silencing suppressed tumor growth via regulating SHMT2 and miR-149-5p in vivo. CONCLUSION: This study demonstrated that circ_0072995 promoted cell malignant phenotypes and anaerobic glycolysis in breast cancer via up-regulating SHMT2 through sponging miR-149-5p, indicating a promising molecular target for breast cancer treatment.