Induction of cancer stem-like cells in A549 cells after exposure to carbon ions and X-rays

Background: cancer stem-like cells (cscs) play a crucial role in the initiation, progression, and recurrence of cancer. evidence indicates that the high linear energy transfer (let) carbon ion beam is more effective against cscs than the conventional x-ray beam. carbon ion radiotherapy is considered as a promising cancer strategy, however, information about whether, or not, new cscs are induced after carcinoma cells exposed to carbon ions is limited and incomplete. materials and methods: the selected a549 cells, derived from a single colony with low cd133 expression, were irradiated by high let carbon ion beam or low let x-ray, and then the cell clonal survival fraction, cd133^+ expression subpopulations and soft agar colony formation potential were detected. results: the cell-killing ability of carbon ions was higher than that of x-rays. the fractions of cd133^+ or oct4^+ high expression cells increased in a dose-dependent manner at 12 h after both x-ray and carbon ion exposure. compared to that of carbon ion irradiation, the efficiency of transformation in a cell colony was higher in the x -ray irradiation group after 30 d; however, the amount of colonies with higher fractions of cd133^+ expression cell subpopulation in the carbon ion irradiation group was more than that in x-ray irradiation treatment group after 30 and 50 d. conclusion: our results indicate that, although high-let radiation kill more cells including cancer stem-like a549 cells, it may induce more stable stem cell-like colonies than low let radiation.