The
antipsychotic drug pimozide has been demonstrated to inhibit
cancer. However, the precise anti-
cancer mechanism of
pimozide remains unclear. The purpose of this study was to investigate the effects of
pimozide on human MCF-7 and MDA-MB-231
breast cancer cell lines, and the potential involvement in the RAF/ERK signaling. The effects of
pimozide on cells were examined by 4,5-dimethylthiazol-2-yl-3,5-diphenylformazan, wound healing, colony formation, transwell assays, and
caspase activity assay. Flow cytometry and
acridine orange and
ethidium bromide staining were performed to assess changes in cells. Transmission electron microscopy and
monodansylcadaverine staining were used to observe autophagosomes. The cyclic
adenosine monophosphate was evaluated using the FRET system. Immunohistochemistry, immunofluorescence, RNA interference, and western blot investigated the expression of
proteins. Mechanistically, we focus on the RAF1/ERK signaling. We detected
pimozide was docked to RAF1 by Schrodinger software.
Pimozide down-regulated the phosphorylation of RAF1, ERK 1/2, Bcl-2, and Bcl-xl, up-regulated Bax, and cleaved
caspase-9 to induce apoptosis.
Pimozide might promote autophagy by up-regulating cAMP. The enhancement of autophagy increased the conversion of LC3-I to LC3-II and down-regulated p62 expression. But mTOR signaling was not involved in promoting autophagy. The knockdown of RAF1 expression induced autophagy and apoptosis in
breast cancer cells, consistent with the results of
pimozide or
sorafenib alone. Blocked autophagy by
chloroquine resulted in the impairment of
pimozide-induced apoptosis. These data showed that
pimozide inhibits
breast cancer by regulating the RAF/ERK signaling pathway and might activate cAMP-induced autophagy to promote apoptosis and it may be a potential drug for
breast cancer treatment.