Background: Hepatocellular carcinoma (HCC) has a high incidence and mortality rate despite various treatment options, including ¹²⁵I seed implantation. However, recurrence and radiation resistance remain challenging issues. Hsa_circ_0007895 (circEYA3)—derived from exons 2–6 of EYA3–facilitates the proliferation and progression of pancreatic ductal adenocarcinoma. However, the role of circEYA3 in HCC ¹²⁵I radiation resistance remains unclear. Thus, we aimed to investigate the functions and underlying molecular mechanisms of circEYA3 in HCC under ¹²⁵I and X-ray irradiation conditions. Methods: CircEYA3 was identified by RNA-seq in patients with HCC before and after ¹²⁵I seed implantation treatment, followed by fluorescence in situ hybridization and RNase R assays. The radiosensitivity of HCC cell lines irradiated with ¹²⁵I seeds or external irradiation were evaluated using the Cell Counting Kit 8, flow cytometry, γH2A.X immunofluorescence and comet assays. RNA pull-down and RNA immunoprecipitation assays were performed to explore the interactions between circEYA3 and IGF2BP2. DTX3L mRNA was identified by RNA-seq in PLC/PRF/5 cells with overexpressed circEYA3. The corresponding in vitro results were verified using a mouse xenograft model. Results: CircEYA3 decreased the radiosensitivity of HCC cells both in vitro and in vivo. Notably, using a circRNA pulldown assay and RNA-binding protein immunoprecipitation, we identified IGF2BP2 as a novel and robust interacting protein of circEYA3. Mechanistically, circEYA3 binds to IGF2BP2 and enhances its ability to stabilize DTX3L mRNA, thereby specifically alleviating radiation-induced DNA damage in HCC cells. Conclusions: Our findings demonstrate that circEYA3 increases the radioresistance of HCC to ¹²⁵I seeds and external irradiation via the IGF2BP2/DTX3L axis. Thus, circEYA3 might be a predictive indicator and intervention option for ¹²⁵I brachytherapy or external radiotherapy in HCC.

Background. 6-Phosphofructo-2-kinase/fructose-2,6-biphosphate-4 (PFKFB4) is a key factor that plays an important role in tumorigenesis. However, its role in triple-negative breast cancer (TNBC) progression needs to be further validated. We investigated whether PFKFB4 is directly involved in the oncogenic signaling networks of TNBC. Methods. First, we assessed the expression level of PFKFB4 in tumor tissue specimens by immunohistochemistry and evaluated its prognostic value. Next, the effect of PFKFB4 on TNBC cell growth and associated mechanisms were investigated. Finally, the results were further verified in vivo. Results. We found that PFKFB4 overexpression was associated with an unfavorable prognosis in TNBC patients. PFKFB4 was overexpressed in TNBC cell lines in hypoxic environments, and its overexpression promoted tumor progression in vitro and in vivo. Further analyses demonstrated that the possible mechanism might be that PFKFB4 overexpression facilitates TNBC progression by enhancing the G1/S phase transition by increasing the protein level of CDK6 and phosphorylation of Rb. Conclusions. These data suggest that PFKFB4 plays significant roles in the tumorigenesis and development of TNBC.