Fig. 4. Effect of SB and IR on induction of DNA damage in EGFR-knockdown DU145 cells. At the end of the treatments, cells were trypsinized briefly and fifteen thousand cells/0.5 mL in low melting point agarose were coated on the surface of a microscopic slide and processed in single cell gel electrophoresis. Slides were further stained with ethidium bromide (4 µg/mL) and subsequently visualized with fluorescent microscope for the images. (A) Representative fluorescent images for various treatments taken at ×100 magnification. Quantitative data represented as (B) comet tail length, and (C) percent content of DNA in tail in respective treatments. Quantitative data presented as mean ± SE of triplicate for each treatment group. Results are representative of three independent experiments. SB, silibinin; IR, ionizing radiation; EGFR, EGF receptor; shEGFR, short hairpin EGF receptor; Gy, gray; SE, standard error; ns, not significant. *P < 0.05, **P < 0.01, ***P < 0.001.

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