Carbon ion irradiation-induced DNA damage evokes cell cycle arrest and apoptosis via the pRb/E2F1/c-Myc signaling pathway in p53-deficient prostate cancer PC-3 cells

Carbon ion radiotherapy has the advantages of better therapeutic effect and fewer side effects compared with those of X-rays in many kinds of tumors, including prostate cancer, and thus is an attractive treatment approach for prostate cancer. However, the biological effects and underlying mechanisms of carbon ion irradiation in prostate cancer are not yet fully understood. Therefore, this study systematically compared the effects of carbon ion irradiation with those of X-ray irradiation on DNA damage response and found that carbon ion irradiation was more effective than X-ray irradiation. Carbon ion irradiation can induce a high level of DNA double-strand break damage, reflected by the number of γ-H2A histone family member X foci, as well as by the foci lasting time and size. Moreover, carbon ion irradiation exhibited strong and long-lasting inhibitory effect on cell survival capability, induced prolonged cell cycle arrest, and increased apoptosis in PC-3 cells. As an underlying mechanism, we speculated that carbon ion irradiation-induced DNA damage evokes cell cycle arrest and apoptosis via the pRb/E2F1/c-Myc signaling pathway to enhance the radiosensitivity of p53-deficient prostate cancer PC-3 cells. Collectively, the present study suggests that carbon ion irradiation is more efficient than X-ray irradiation and may help to understand the effects of different radiation qualities on the survival potential of p53-deficient prostate cancer cells.