Circ-ZNF609 Accelerates the Radioresistance of Prostate Cancer Cells by Promoting the Glycolytic Metabolism Through miR-501-3p/HK2 Axis.

Background: The development of radioresistance remains the obstacle for prostate cancer (PCa) treatment. Here, we explored the role and potential mechanism of circular RNA zinc finger protein 609 (circ-ZNF609) in the radioresistance of PCa cells. Materials and Methods: Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of circ-ZNF609, microRNA-501-3p (miR-501-3p) and hexokinase 2 (HK2) messenger RNA (mRNA). The viability, apoptosis, metastasis and radioresistance of PCa cells were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry, transwell assays and colony formation assay. The glycolytic rate was assessed through measuring the glucose consumption and lactate production using fluorescence-based glucose and lactate assay kits. The target interaction between miR-501-3p and circ-ZNF609 or HK2 was predicted by StarBase software and confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The protein level of HK2 was detected by Western blot assay. In vivo tumor growth assay was used to explore the role of circ-ZNF609 in the radioresistance of PCa in vivo. Results: Circ-ZNF609 was abnormally up-regulated in PCa tissues and cell lines. Circ-ZNF609 silencing hampered the viability, metastasis, radioresistance and promoted the apoptosis through suppressing cell glycolysis. MiR-501-3p was a direct target of circ-ZNF609, and si-circ-ZNF609-induced influence in PCa cells was partly alleviated by the addition of anti-miR-501-3p. MiR-501-3p functioned through directly interacting with and down-regulating HK2. HK2 was modulated by circ-ZNF609/miR-501-3p axis in PCa cells. Circ-ZNF609 silencing enhanced the radiosensitivity of PCa cells in vivo. Conclusion: Circ-ZNF609 promoted the progression and radioresistance of PCa cells through accelerating the glycolysis via miR-501-3p/HK2 axis, providing promising targets for improving the prognosis of PCa patients.