The Radiosensitive Study Of CD133-positive Glioma Stem Cells In Vitro

Objective: To investigate the differences of radiosensitivity and DNA double-strandbreaks (DSBs) damage between CD133-positive (CD133+) glioma stem cells andCD133-negative (CD133-) non-stem cells in vitro.Methods: CD133+and CD133-cells were isolated from glioma U251and U87celllines by flow cytometry sorter system. The radiosensitivity of CD133+and CD133-cellswere measured by clone forming assay. The DSBs damage of CD133+and CD133-cellswere determined by immunofluorescence of γ-H2AX foci.Results: For glioma U251and U87cell lines, The clone forming rate of CD133+cells was higher than CD133-cells (t=3.339, p=0.003；t=3.721，p=0.004). After receiving4Gy irradiation, for U251cell line，the clone forming rates of CD133+and CD133-decreased by25%and38%compared to non-irradiation, respectively (t=2.837, p=0.011;t=4.717, p=0.000);for U87cell line, the clone forming rates of CD133+decreased by16%compared to non-irradiation.(t=0.65， p=0.55). The clone forming rates of CD133-decreased by50%compared to non-irradiation.(t=3.162，p=0.025). For both U251andU87cell lines, compared to non-irradiation, the expression of γ-H2AX foci for bothCD133+and CD133-cells increased significantly at0.5h and6h after receiving4Gyirradiation, and the expression level of γ-H2AX foci was no significant difference betweenCD133+and CD133-cells (U251:t=0.038, p=0.973; t=0.764, p=0.524.U87: t=0.119，p=0.911；t=0.378，p=0.991). The expression of γ-H2AX foci decreased at24h compared toat0.5h and6h. Moreover, for U251and U87cell lines, the expression level of γ-H2AXfoci for CD133+cells was lower than CD133-cells significantly (t=22.69, p=0.002;t=4.989，p=0.008). Conclusions: Glioma stem cells are more radioresistance than glioma non-stem cells.The probable mechanism is that the DSBs repair capacity of glioma stem cells is morepowerful than non-stem cells.