Figure 2.

Notch pathway as a candidate therapeutic target in breast tumors. CD44‐positive and negative MCF7 cells were studied by FACS analysis and immunoblot with anti‐Notch1, Notch3, and actin antibodies. (a) siRNAs knockdown of Notch1 and Notch3. siRNAs of Notch1 (144334; NM_017617) and Notch3 (143322; NM_000435) were used (Ambion‐Applied Biosystems). (b) MTS proliferation assay (Promega, San Luis Obispo, CA, USA) of CD44⁺‐ and CD44⁻ breast cancer MCF7 cells with knockdown of Notch1 and Notch3. Cells (2 × 10³ per well) were seeded and grown in 96‐well plat bottom plates for 24 hours. After cells were treated by radiation exposure at 4 Gy, cells were allowed to grow in a 37°C incubator for indicated periods and the absorbance at 490 nm was measured. The average data was calculated in comparison with the control result and the percent inhibition is shown. Each character (* and #) indicates statistical significance (P < 0.05). (c) Schema represents CD44⁺ CD24(–/low) breast cancer stem cells (CSCs) resistant to therapy.