Identification of penfluridol as potential treatment for pancreatic cancer cells

Abstract

Tyrosine kinase inhibitors (TKIs) have provided promising anti-cancer activities, but intrinsic or acquired resistance to these drugs is a major problem. To overcome this resistance, we have used microarray analysis to identify a signature of intrinsic drug resistance in human pancreatic cancer cells, and applied this gene expression profile to silico drug screening for potential drugs for pancreatic cancer therapy. The potency of dasatinib (a multiple family TKI) was assessed against a panel of 14 human pancreatic cancer cell lines. This drug is undergoing clinical trials for pancreatic cancers. Nine of fourteen pancreatic cell lines were growth inhibited by dasatinib. Three dasatinib-resistant (MiaPaCa2, Panc1, SU8686) and three -sensitive (Panc0504, Panc1005, Panc0403) pancreatic cancer cell lines were used in microarray analysis to compare the gene expression profiles. A total of 598 genes were differentially expressed in dasatinib-resistant cell lines compared to the sensitive cell lines. To discover therapeutic drugs that sensitize pancreatic cancer cells to dasatinib, we performed in silico drug screening using the Connectivity Map database (CMAP). The gene signature induced by thioridazine in CMAP showed a �glove in hand� pattern to that found in dasatinib-resistant versus -sensitive pancreatic cancer cell lines. Thioridazine belongs to the phenothiazine family including chlorpromazine, perphenazine, penfluridol, and pimethixene. Each was examined. Assays of cell proliferaton, cell cycle, and Annexin V showed that each was effective at inhibiting the cell cycle and inducing apoptosis. Penfluridol (a calcium channel inhibitor) was the most potent against both the dasatinib-resistant and -sensitive pancreatic cancer cell lines. Drug combination studies of penfluridol and either dasatinib or gemcitabine (FDA-approved for pancreatic cancer) showed synergistic enhancement of cytotoxicity. Mechanistic investigations suggested that multiple signaling pathways were suppressed by penfluridol. These studies suggest a potential novel class of drugs for treatment of pancreatic cancers.