Fisetin micelles precisely exhibit a radiosensitization effect by inhibiting PDGFRβ/STAT1/STAT3/Bcl-2 signaling pathway in tumor

It is of great significance to find safe and effective radiosensitizers. A primary investigation has been made on fisetin's modification of radiation effect, but its radiosensitization and related mechanisms still need to be deeply clarified. Furthermore, fisetin with high hydrophobicity is difficult to dissolve in water, severely limiting its research and application. In this study, we fabricated a safe and soluble radiosensitizer fisetin micelle for precisely enhancing radiotherapy by inhibiting platelet-derived growth factor receptor-β (PDGFRβ)/signal transducer and activator of transcription 1 (STAT1)/signal transducer and activator of transcription 3 (STAT3)/B cell lymphoma 2 (Bcl-2) signaling pathway in the tumor. Systematic and detailed studies were performed to verify its radiosensitization effect in vitro and in vivo. On the cellular level, fisetin micelles selectively increased the radiosensitivity of tumor cells (CT26 and 4T1 cells) and had little effect on the sensitivity of normal mouse cells (L929 cells) to radiation. In the mouse models of colon and breast cancers, fisetin micelles showed an efficient radiosensitization capacity without apparent toxicity. Additionally, we first found that fisetin micelles played a radiotherapy sensitization role by inhibiting the PDGFRβ/STAT1/STAT3/Bcl-2 pathway activity. In general, this work not only confirmed that fisetin micelles precisely exhibit a radiosensitization effect in vitro and in vivo, but also profoundly explored its mechanisms underlying, to provide a theoretical and experimental basis for the clinical application of fisetin micelles.