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Figure 2 | Breast Cancer Research

Figure 2

From: The estrogen receptor influences microtubule-associated protein tau (MAPT) expression and the selective estrogen receptor inhibitor fulvestrant downregulates MAPT and increases the sensitivity to taxane in breast cancer cells

Figure 2

Downregulation of MAPT expression and alteration of cellular sensitivity to taxanes. A: Downregulation of MAPT expression with siRNA. siRNA was used to knock down MAPT expression in ZR75-1 and HCC3153 cells. Cells were harvested 72 hours after transfection for Western blot analysis. B: Cell viability determined by an MTS assay after the knockdown of MAPT. Cells were seeded 24 hr after transfection on a 96-well plate at 5 × 103 cells/well and incubated for 24 hr. The cells were then cultivated for 72 hr in the presence of various concentrations of drugs. After this treatment, four independent MTS assays were performed. The data shown are the average of these four assays. In ZR75-1 cells knockdown of MAPT significantly increased sensitivity to taxanes, but did not alter sensitivity to vinorelbine or doxorubicin. In HCC3153 cells knockdown of MAPT did not alter sensitivity to taxanes. *P < 0.05, indicates a significant difference, compared with the control (unpaired Student's test). C: Analysis of the cell cycle using flow cytometry. At 24 hr after transfection, cells were exposed to low-dose paclitaxel (25 nM) for 72 hr. Afterwards, a cell cycle analysis was performed using flow cytometry. The percentage of cells in the G2/M phase was higher in cells that had been exposed to low-dose taxanes after MAPT knockdown, compared with the controls. (The data show ZR75-1 cells with paclitaxel.) D: Analysis of cell cycle and cell proliferation using immunofluorescence. After transfection, cells were seeded on six-well plates and incubated for 24 hr. After this treatment, the cells were exposed to low-dose paclitaxel (25 nM) for 24 hr. Immunofluorescence with an anti-α-tubulin antibody was then performed. Paclitaxel caused an increase in apoptotic cells from 14/100 cells (that is, the control cells) to 29/100 cells (that is, MAPT knockdown cells). There was also repressed proliferation, compared with the controls. (The arrows indicate apoptotic ZR75-1 cells.)

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