Cancer-Targeted Selenium Nanoparticles Sensitize Cancer Cells to Continuous γ Radiation to Achieve Synergetic Chemo-Radiotherapy.

Cancer radiotherapy with 125 I seeds demonstrates higher long-term efficacy and fewer side effects than traditional X-ray radiotherapy owing to its low-dose and continuous radiation but is still limited by radioresistance in clinical applications. Therefore, the design and synthesis of sensitizers that could enhance the sensitivity of cancer cells to 125 I seeds is of great importance for future radiotherapy. Selenium nanoparticles (SeNPs) have been found to exhibit high potential in cancer chemotherapy and as drug carriers. In this study, we found that, based on the Auger-electron effect and Compton effect of Se atoms, cancer-targeted SeNPs in combination with 125 I seeds achieve synergetic effects to inhibit cancer-cell growth and colony formation through the induction of cell apoptosis and cell cycle arrest. Detailed studies on the action mechanisms reveal that the combined treatments effectively activate intracellular reactive oxygen species (ROS) overproduction to regulate p53-mediated DNA damage apoptotic signaling pathways and mitogen-activated protein kinase (MAPK) phosphorylation and to prevent the self-repair of cancer cells simultaneously. Taken together, the combination of SeNPs with 125 I seeds could be further exploited as a safe and effective strategy for next-generation cancer chemo-radiotherapy in clinical applications.