2908 - Enhancing Cancer Therapy: Synergistic Effects of Withaferin A and Ionizing Radiation on Lung Cancer Cells

Y. J. Wang^1,2, S. Y. Liu³, and J. M. Lai³; ¹School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan, ²Department of Radiation Oncology, Fu Jen Catholic University Hospital, New Taipei City, Taiwan, ³Fu Jen Catholic University, New Taipei City, Taiwan

Purpose/Objective(s): This research explores the efficacy of Withaferin A (WA) as a radiosensitizer to ionizing radiation (IR) in the augmentation of cancer cell mortality, particularly focusing on lung cancer cells. Materials/

Methods: The study utilized non-small cell adenocarcinoma cell line (A549) lung cancer cell lines, subjecting them to varying degrees of ionizing radiation with and without pre-treatment of WA. The assessment of cytotoxic impacts utilized clonogenic assays, while cell cycle alterations were monitored through flow cytometry post-DAPI staining. To elucidate the mechanisms underlying cell death, we analyzed the activation of the DNA damage response, apoptotic pathways, and the formation of ?-H2AX foci through immunoblotting and immunofluorescence staining techniques.
Results: Our results delineate a dose-responsive attenuation of A549 cell proliferation attributable to IR, which is significantly augmented by WA pre-treatment. Notably, WA enhanced the IR-induced DNA damage and apoptosis, as evidenced by increased levels of p-CHK2, p-p53, ?-H2AX, p21, and cleaved-PARP. Furthermore, the observed upregulation of BiP indicates a potential role of endoplasmic reticulum (ER) stress in mediating cell death, introduced by WA in concert with IR. The increased incidence of G2/M phase cells post-treatment suggests that mitotic catastrophe may serve as a critical mechanism in the enhanced sensitivity to IR observed with WA pre-treatment.
Conclusion: Our findings propose Withaferin A as a viable radiosensitizer in the therapeutic regimen for lung cancer, enhancing the efficacy of radiation therapy through the potentiation of the DNA damage response, apoptosis induction, and mitotic catastrophe. These insights underscore the potential of WA to improve clinical outcomes in lung cancer treatment when combined with conventional radiation therapy.