Circ_0022587 Regulates Tumor Properties of Human Breast Cancer Cells by Targeting miR‐335‐5p/Phosphoglycerate Kinase 1 Pathway

Increasing research indicates that circular RNAs (circRNAs) affect the development of breast cancer (BC) through specific molecular mechanisms. However, there is no data regarding the role of circ_0022587 in BC progression. This investigation aims to reveal the mechanism of circ_0022587 in regulating the malignant progression of BC. The study recruited 27 BC patients undergoing a surgical operation in Nantong First People's Hospital, Affiliated Hospital 2 of Nantong University. Quantitative real-time polymerase chain reaction and RNase R degradation assay were used to verify the circular structure of circ_0022587. 3-(4,5-Dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide, 5-Ethynyl-2'-deoxyuridine, flow cytometry analysis, transwell and tube formation assays were used to detect the viability, proliferation, apoptosis, invasion and tumor angiogenesis of BC cells, respectively. Glycolysis was evaluated by glycolysis metabolism assays. The associations among miR-335-5p, circ_0022587 and phosphoglycerate kinase 1 (PGK1) were identified by dual-luciferase reporter assays and RNA immunoprecipitation. The effects of circ_0022587 knockdown on tumor growth were evaluated by xenograft nude mouse model assays. The positive expression rates of PGK1, nuclear proliferation marker and matrix metalloprotein 9 were analyzed by immunohistochemistry assays. The results showed that circ_0022587 expression was upregulated in BC tumor tissues and BC cells. Downregulation of circ_0022587 inhibited cell viability, proliferation, invasion ability, tube angiogenesis and glycolysis, and promoted cell apoptosis. Overexpression of circ_0022587 relieved the effect of glycolysis inhibitor (2-Deoxy-D-glucose, 2-DG) on glucose consumption, lactate production, and ATP/ADP ratios. In addition, circ_0022587 interacted with miR-335-5p, and miR-335-5p inhibitors attenuated circ_0022587 silencing-induced effects in BC cells. miR-335-5p bound to PGK1, and PGK1 overexpression relieved miR-335-5p mimics-induced effects in BC cells. Further, circ_0022587 knockdown inhibited tumor formation in vivo. The above results demonstrate that circ_0022587 regulates PGK1 expression by absorbing miR-335-5p, thereby affecting BC development, which may provide a new therapeutic strategy for BC. The study's novelty and innovative potential lie in its discovery of a new regulatory mechanism involving circ_0022587 in the miR-335-5p/PGK1 pathway and its potential clinical relevance. These aspects contribute to the expanding knowledge base of breast cancer research and could potentially lead to improved therapeutic strategies in the future.