Doxorubicin Promotes Migration and Invasion of Breast Cancer Cells through the Upregulation of the RhoA/MLC Pathway

Figures

• 

  Figure 1. Effects of brief treatment with cytotoxic drugs on the phenotype of MCF7 breast cancer cells. Colony formation (A), cell migration (B) and invasion (C) assays were performed in MCF7 cells treated briefly with paclitaxel (30 nM) for 1 hour, doxorubicin (200 nM) for 3 hours, or vehicle control. (D) Invasion assay of MCF7 cells treated with paclitaxel (30 nM) for 1 hour, doxorubicin (200 nM) for 3 hours, or a combination of both in different sequences. *p < 0.05 versus control; †p < 0.01; ‡p < 0.001.

• 

  Figure 2. Effects of brief treatment with doxorubicin or paclitaxel on cell migration (A, C) and invasion (B, D) in BT-474 breast cancer cells (A, B) and ES-2 ovarian cancer cells (C, D). Cells were pretreated with paclitaxel (30 nM) for 1 hour, doxorubicin (200 nM or 800 nM) for 3 hours, or vehicle control and migration and invasion assays were performed. *p < 0.05 versus control; †p < 0.01.

• 

  Figure 3. Effects of brief treatment with cytotoxic drugs on the expression of cell motility factors and RhoA activity in MCF7 breast cancer cells. (A) Cells were treated with paclitaxel (30 nM) for 1 hour or doxorubicin (200 nM) for 3 hours. The media were replaced, and cells were maintained in standard culture medium further for 24 to 48 hours. Cell lysates were prepared and western blotting was performed. (B) Cells were treated with paclitaxel (30 nM) or doxorubicin (200 nM) for 30 minutes. Cell lysates were prepared and RhoA activity was determined. IKK = IκB kinase; MLC = myosin light chain. *p < 0.01 versus control.

• 

  Figure 4. Rescue effects of RhoA inhibitors on cell migration and invasion promoted by doxorubicin in breast cancer cells. MCF7 (A, C) and BT-474 (B, D) cells were pretreated with or without Y16 (50 μM) or rhosin/G04 (50 μM) for 24 hours and incubated with doxorubicin (MCF7, 200 nM; BT-474, 800 nM) or vehicle control for an additional 3 hours. Then, cells were re-suspended and migration and invasion assays were performed. *p < 0.05 versus control; †p < 0.01; ‡p < 0.05 versus doxorubicin only; §p < 0.01.