Chinese Herbal Mixture, Tien-Hsien Liquid, Induces G2/M Cycle Arrest and Radiosensitivity in MCF-7 Human Breast Cancer Cells through Mechanisms Involving DNMT1 and Rad51 Downregulation

Figure 7

THL decreased DNA double-strand break repair protein Rad51 in MCF-7 cells but increased the level of the protein in primary HS68 fibroblast cells. (a) (A) THL dose-dependently decreased the homologous recombination DNA repair protein Rad51 in MCF-7 cells. (B) Pretreatment with THL dose-dependently decreased the Rad51 protein level in irradiated MCF-7 cells but did not reduce the nonhomologous end joining DNA repair proteins Ku70 and Ku86. (C) In contrast to its effect on MCF-7 cells, THL increased the Rad51 protein level in HS68 human foreskin fibroblast cells. In (A) and (C), cells were treated with PBS or THL for 72 h and then harvested. In (B), cells were pretreated with THL for 24 h and then irradiated with 6 Gy of ionizing radiation. Cells were harvested 24 h after irradiation, after which cell lysates were prepared for Western blot analysis. (b) The blots were normalized to actin or tubulin, and the fold change protein level expression is reported in comparison to PBS-treated control.