title: Anti-malaria drug blocks proteotoxic stress response: anti-cancer implications.
abstract: The number of physical conditions and chemical agents induce accumulation of misfolded proteins creating proteotoxic stress. This leads to activation of adaptive pro-survival pathway, known as heat shock response (HSR), resulting in expression of additional chaperones. Several cancer treatment approaches, such as proteasome inhibitor Bortezomib and hsp90 inhibitor geldanamycin, involve activation of proteotoxic stress. Low efficacy of these therapies is likely due to the protective effects of HSR induced in treated cells, making this pathway an attractive target for pharmacological suppression. We found that the anti-malaria drugs quinacrine (QC) and emetine prevented HSR in cancer cells, as judged by induction of hsp70 expression. As opposed to emetine, which inhibited general translation, QC did not affect protein synthesis, but rather suppressed inducible HSF1-dependent transcription of the hsp70 gene in a relatively selective manner. The treatment of tumor cells in vitro with a combination of non-toxic concentrations of QC and proteotoxic stress inducers resulted in rapid induction of apoptosis. The effect was similar if QC was substituted by siRNA against hsp70, suggesting that the HSR inhibitory activity of QC was responsible for cell sensitization to proteotoxic stress inducers. QC was also found to enhance the antitumor efficacy of proteotoxic stress inducers in vivo: combinatorial treatment with 17-DMAG + QC resulted in suppression of tumor growth in two mouse syngeneic models. These results reveal that QC is an inhibitor of HSF1-mediated HSR. As such, this compound has significant clinical potential as an adjuvant in therapeutic strategies aimed at exploiting the cytotoxic potential of proteotoxic stress.
authors.affiliation: Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY, USA.
authors.forename: Nickolay
authors.initials: N
authors.lastname: Neznanov
authors.forename: Anton V
authors.initials: AV
authors.lastname: Gorbachev
authors.forename: Lubov
authors.initials: L
authors.lastname: Neznanova
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Komarov
authors.forename: Katerina V
authors.initials: KV
authors.lastname: Gurova
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Gasparian
authors.forename: Amiya K
authors.initials: AK
authors.lastname: Banerjee
authors.forename: Alexandru
authors.initials: A
authors.lastname: Almasan
authors.forename: Robert L
authors.initials: RL
authors.lastname: Fairchild
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Gudkov
mesh_terms: D000962:Antimalarials / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D016227:Benzoquinones / Q000494:pharmacology; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D004268:DNA-Binding Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000187:drug effects*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D009369:Neoplasms / Q000188:drug therapy; D011719:Pyrazines / Q000494:pharmacology; D011796:Quinacrine / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D000962:Antimalarials; D000970:Antineoplastic Agents; D016227:Benzoquinones; D001897:Boronic Acids; D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D047029:Lactams, Macrocyclic; D011719:Pyrazines; D034741:RNA, Small Interfering; D014157:Transcription Factors; D000069286:Bortezomib; D011796:Quinacrine; C001277:geldanamycin