Effects of X-ray irradiation in combination with ascorbic acid on tumor control

Abstract

Our previous studies demonstrated that the combination of treatment with ascorbic acid (AsA) and X-ray irradiation results in increased apoptosis in HL60 cells. The present study was performed to investigate the effects of the combined use of AsA and X-ray irradiation on epithelial cancer and sarcoma cells, and its potential use in future clinical treatment. X-ray irradiation combined with AsA treatment resulted in increased suppression of cell growth of HT1080, SAS and A549 cells in vitro compared with X-ray irradiation alone. The combined treatment also suppressed tumor growth in implanted HT-1080 cells in vivo. Using annexin V/propidium iodide staining and the detection of activated caspase 3, it was found that X-ray irradiation increased the apoptotic rate of HT1080 cells and resulted in G2/M arrest. However, apoptosis in the HT1080 cells treated with 5 mM AsA remained unchanged, and no changes were observed in the G2/M fraction. By contrast, AsA treatment caused increased suppression of proliferation compared with X-ray irradiation. These results suggested that 5 mM AsA slowed the cell cycle and reduced tumor growth. Therefore, X-ray irradiation combined with AsA treatment may be effective against epithelial cancer and sarcoma cells.