Thioridazine combined with carboplatin results in synergistic inhibition of triple negative breast cancer by targeting cancer stem cells

•Thioridazine (THZ) demonstrated the capability of destroying breast cancer stem cells and this effect was amplified when combined with carboplatin (CBP) treatment.•Tumor growth and lung metastasis in 4T1-bearing mice were markedly inhibited by CBP combined with THZ.•Suppression of PI3K/AKT/mTOR pathway and activation of estrogen receptor (ER) stress are involved in CBP combined with THZ treatment group both in vitro and in vivo.