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 4

THL downregulated DNMT1 and DNMT3A accompanied by the induction of cyclin-dependent kinase inhibitors (p21 and p15) and the reduction of pRb phosphorylation in MCF-7 cells. THL also diminished the DNMT1 protein level in BT-474 cells. (a) (A) THL dose-dependently decreased the protein levels of DNMT1 and DNMT3A in MCF-7 cells. (B) THL dose-dependently increased the protein level of p21. (C) THL dose-dependently increased the protein level of p15. (D) THL dose-dependently decreased the phosphorylation (inactivation) of Rb protein (pRb) in MCF-7 cells. (E) THL dose-dependently diminished the protein level of DNMT1 in BT-474 cells. Cells were treated with PBS (control) or THL for 72 h and then harvested. Cell lysates were then prepared for Western blot analysis. (b) The blots were normalized to tubulin or GAPDH, and the fold change protein level expression is reported in comparison to PBS-treated control.