Abstract: Objective To study the effect of thioridazine on the proliferation and apoptosis of human colorectal cancer SW480
cells. Methods SW480 cells were treated with different concentrations of thioridazine, and MTT assay was used to evaluate the
cell inhibition rate. Hoechst 33342 staining was performed to demonstrate the cell morphology changes. Flow cytometry was
used to determine the cell apoptosis and cell cycle changes. RT-qPCR was used to detect PDCD4, c-MYC, BCL2, CCND1,
CASPASE3, PARP1, CDK4 and EIF4A mRNA expressions, and Western blotting was employed to assay AKT, p-AKT, and
PDCD4 protein expression levels. Results MTT results showed that thioridazine inhibits the proliferation of SW480 cells.
SW480 cells treated with thioridazine presented with such typical features of apoptosis of karyopyknosis, chromatin
condensation and nuclear fragmentation. Flow cytometry showed that thioridazine was a cell cycle-specific drug and caused
cell cycle arrest at G1/G0 phase and an increased cell apoptosis rate. Thioridazine treatment of the cells resulted in up-regulated
PDCD4 mRNA expression and down-regulated mRNA expressions of CCND1, CDK4, c-MYC, BCL2, CASPASE3, PARP1 and
EIF4A, increased PDCD4 protein expression and reduced p-AKT protein expression. Conclusion Thioridazine inhibits the
proliferation and induces apoptosis of SW480 cells by up-regulating PDCD4 and inhibiting PI3K/Akt pathway.