title: Chloroquine synergizes with FTS to enhance cell growth inhibition and cell death.
abstract: The Ras family of small GTPases transmits extracellular signals that regulate cell growth, differentiation, motility and death. Ras signaling is constitutively active in a large number of human cancers. Ras can also regulate autophagy by affecting several signaling pathways including the mTOR pathway. Autophagy is a process that regulates the balance between protein synthesis and protein degradation. It is important for normal growth control, but may be defective in diseases. Previously, we have shown that Ras inhibition by FTS induces autophagy, which partially protects cancer cells and may limit the use of FTS as an anti-cancer drug. Since FTS is a non toxic drug we hypothesized that FTS and chloroquine (an autophagy inhibitor) will synergize in cell growth inhibition and cell death. Thus, in the present study, we explored the mechanism of each individual drug and their combined action. Our results demonstrate that in HCT-116 and in Panc-1 cells, FTS induces autophagy, which can be inhibited by chloroquine. Furthermore, the combined treatment synergistically decreased the number of viable cells. Interestingly, the combined treatment enhanced apoptotic cell death as indicated by increased sub-G1 cell population, increased Hoechst staining, activation of caspase 3, decrease in survivin expression and release of cytochrome c. Thus, chloroquine treatment may promote FTS-mediated inhibition of tumor cell growth and may stimulate apoptotic cell death.
authors.affiliation: Department of Neurobiology. Tel-Aviv University, Ramat-Aviv, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Schmukler
authors.forename: Eya
authors.initials: E
authors.lastname: Wolfson
authors.forename: Roni
authors.initials: R
authors.lastname: Haklai
authors.forename: Galit
authors.initials: G
authors.lastname: Elad-Sfadia
authors.forename: Yoel
authors.initials: Y
authors.lastname: Kloog
authors.forename: Ronit
authors.initials: R
authors.lastname: Pinkas-Kramarski
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000008:administration & dosage / Q000494:pharmacology*; D005204:Farnesol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D045325:HCT116 Cells; D006801:Humans; D051381:Rats; D012459:Salicylates / Q000008:administration & dosage / Q000494:pharmacology*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
chemical_list: D012459:Salicylates; C093323:farnesylthiosalicylic acid; D005204:Farnesol; D002738:Chloroquine; D058570:TOR Serine-Threonine Kinases; D018631:ras Proteins