Laser-Generated Ultrashort Pulsed Electron Beams Induce p53-Related Alteration of DNA Repair and Cell Death Pathways...

Laser-driven accelerated particle beams have significantly advanced cancer treatment by facilitating the delivery of exceptionally high dose rates of radiation to solid tumors within femto- to picosecond timescales. This investigation compared the radiobiological effectiveness of ultrashort pulsed electron beams, generated by the Advanced Research Electron Accelerator Laboratory (AREAL) accelerator, with conventional X-rays on two non-small cell lung cancer (NSCLC) cell lines: A549 (wild-type p53) and H1299 (p53-deficient). NSCLC cells were irradiated using either the AREAL accelerator (with a peak dose rate of 1.6 × 10¹⁰ Gy/s, a pulse duration of 4.5 × 10^-13 s, and a repetition rate of 20 Hz) or an X-ray unit at an absorbed dose rate of 0.85 Gy/min. Clonogenic survival analysis, γH2AX foci enumeration, and genome-wide transcriptome analysis were conducted. Clonogenic survival curves showed increased radiosensitivity of A549 cells following AREAL exposure compared to X-rays (RBE = 1.2), whereas H1299 radiosensitivity remained unchanged. In both cell lines, AREAL exposure resulted in a greater dose-dependent accumulation of residual γH2AX foci 24 h after irradiation than conventional X-rays, suggesting more persistent DNA damage signaling. Transcriptomic analyses revealed broader gene expression changes after AREAL irradiation and suggested distinct p53-related responses. Pathway-level analysis demonstrated that A549 cells exhibited reduced DNA repair activity, accompanied by dysregulation of cell cycle progression and apoptosis, whereas H1299 cells displayed transcriptomic signatures consistent with enhanced homologous recombination activity. Overall, these findings indicate that ultrashort pulsed electron beams induce p53-related responses distinct from those of conventional X-rays and warrant further investigation of this technology as a potential radiotherapy modality.