Thioridazine has potent antitumor effects on lung cancer stem-like cells

Abstract

Thioridazine (TDZ), originally an anti-psychotic drug, suppresses several types of cancer and has specificity for leukemia stem cells. The present study was performed to assess its effect on lung cancer stem‑like cells, as its effect remains unknown. TDZ was utilized to treat lung cancer stem‑like cells (A549 sphere cells) and its cytotoxic effect and mechanism were evaluated in vitro and in vivo. TDZ elicited cytotoxicity in A549 sphere cells and inhibited their proliferation in a dose‑dependent pattern. A549 sphere cells treated with TDZ showed nuclear fragmentation, increased G0/G1 phase distribution, positive Annexin V staining, and a change in the expression of caspase family and cell cycle‑associated proteins. These results suggest the induction of caspase‑dependent apoptosis and cell cycle arrest. In addition, TDZ treatment resulted in significant inhibitory effect on mice xenografts established by A549 sphere cells. TDZ repressed growth of lung cancer stem‑like cells in vitro and in vivo, indicating its potential application in targeting lung cancer stem‑like cells.