Targeted inhibition of Notch1 gene enhances the killing effects of paclitaxel on triple negative breast cancer cells.

Objective: To study the influence of targeted inhibition of Notch1 gene on the killing effects of paclitaxel on triple negative breast cancer cells.

Methods: The triple negative [estrogen receptor (ER)/progesterone receptor (PR)/human epidermal growth factor receptor 2 (Her2)] breast cancer cell line MDA-MB-231 and ER/PR/HER-2-positive breast cancer cell line MCF-7 were cultured, transfected with Notch1-siRNA-overexpression plasmid and blank plasmid, and treated with different concentrations of paclitaxel, and then the cell proliferation activity and apoptosis rate as well as the mRNA expression of Caspase-3, Caspase-9 and Bcl-2 were determined.

Results: Paclitaxel could decrease the MDA-MB-231 and MCF-7 cell proliferation activity as well as Bcl-2 mRNA expression, and increase MDA-MB-231 and MCF-7 cell apoptosis rate as well as Caspase-3 and Caspase-9 mRNA expression in dose-dependent manners; with the same dose of paclitaxel treatment, the inhibitory effects on MDA-MB-231 cell proliferation activity and Bcl-2 mRNA expression as well as the promoting effects on MDA-MB-231 cell apoptosis and mRNA expression of Caspase-3 and Caspase-9 were weaker than those on MCF-7 cell; after 0.5 μM paclitaxel combined with Notch1-siRNA treatment, MDA-MB-231 cell proliferation activity and Bcl-2 mRNA expression were significantly lower than those after 0.5 μM paclitaxel combined with control plasmid treatment while cell apoptosis rate and mRNA expression of Caspase-3 and Caspase-9 were higher than those after 0.5 μM paclitaxel combined with control plasmid treatment.

Conclusions: Targeted inhibition of Notch1 gene may enhance the killing effects of paclitaxel on triple negative breast cancer cells by up-regulating the expression of Caspase-3 and Caspase-9 and inhibiting the expression of Bcl-2.