Circ-ABCC4 contributes to prostate cancer progression and radioresistance by mediating miR-1253/SOX4 cascade

Circular RNAs (circRNAs) exert pivotal functions in many malignancies. However, the roles of circ-ABCC4 in prostate cancer (PCa) radioresistance and progression remain largely unclear. Cell viability, proliferation, apoptosis, invasion, and radioresistance were evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, 5-ethynyl-2'-deoxyuridine, flow cytometry, transwell invasion, and colony formation assays. Tumor xenograft experiment was conducted to assess circ-ABCC4 role in xenograft growth in vivo. Dual-luciferase reporter assay was implemented to test the target relation of microRNA-1253 (miR-1253) and circ-ABCC4 or SRY-box transcription factor 4 (SOX4). Circ-ABCC4 enrichment was prominently raised in PCa tissue specimens and cells. Circ-ABCC4 depletion blocked PCa cell viability, proliferation, invasion, and radioresistance and triggered apoptosis. Circ-ABCC4 silencing aggravated irradiation-induced inhibitory effect on xenografts growth. miR-1253 was a downstream molecule of circ-ABCC4, and circ-ABCC4 depletion-mediated anti-cancer impacts in PCa cells were partly counteracted by decreasing miR-1253 abundance. miR-1253 targeted SOX4 mRNA, and miR-1253 blocked PCa cell malignant phenotypes partly by targeting SOX4. Circ-ABCC4 could enhance SOX4 abundance by absorbing miR-1253. Circ-ABCC4 exerted a pro-tumor activity by facilitating PCa cell viability, proliferation, invasion, and radioresistance and suppressing apoptosis.