title: Potential small-molecule activators of caspase-7 identified using yeast-based caspase-3 and -7 screening assays.
abstract: Caspases-3 and -7 are at the core of the execution phase of apoptosis. The search for activators of these proteases has therefore deserved particular attention in the field of anticancer drug discovery. Here, a simplified yeast-based screening approach was developed and used to search for activators of caspases-3 and -7, followed by evaluation of the activity of the selected compounds in the human tumor cell lines HL-60 (acute promyelocytic leukemia) and MCF-7 (breast adenocarcinoma). By using the yeast approach, two potential activators of caspase-7, 5,6-dihydroxy-7-prenyloxyflavone (1a) and 3-hydroxy-7-geranyloxyflavone (2a), were identified. Unlike the known caspases-3 and -7 activator, the procaspase activating compound-1 (PAC-1), these flavonoids did not interfere with the caspase-3 activity in yeast. Moreover, flavonoids 1a and 2a processed procaspase-7 to the active caspase-7 both in yeast and in vitro processing assays, and inhibited the growth of HL-60 and MCF-7 human tumor cells with higher potencies than PAC-1, particularly in the absence of caspase-3 (MCF-7 cells). In MCF-7 cells, the flavonoids processed procaspase-7, increased its activity and sensitized these cells to the effects of the cytotoxic drug, etoposide. In conclusion, the developed yeast target-based screening assays led to the identification of potential caspase-7 activators. A proof of concept is therefore provided for the effectiveness of the yeast assays in the discovery of caspase activators. Additionally, the identified compounds may pave the way for a new class of caspase activators with improved anticancer properties.
authors.affiliation: REQUIMTE, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal; Laboratório de Microbiologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal.
authors.forename: Clara
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Cancer Drug Resistance Group, IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Rua Doutor Roberto Frias, 4200 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Rua dos Bragas n° 289, 4050-123 Porto, Portugal.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Lopes-Rodrigues
authors.affiliation: REQUIMTE, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal; Laboratório de Microbiologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Coutinho
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Rua dos Bragas n° 289, 4050-123 Porto, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), and Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal.
authors.forename: Marta P
authors.initials: MP
authors.lastname: Neves
authors.affiliation: Cancer Drug Resistance Group, IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Rua Doutor Roberto Frias, 4200 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Rua dos Bragas n° 289, 4050-123 Porto, Portugal.
authors.forename: Raquel T
authors.initials: RT
authors.lastname: Lima
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Rua dos Bragas n° 289, 4050-123 Porto, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), and Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal.
authors.forename: Madalena
authors.initials: M
authors.lastname: Pinto
authors.affiliation: Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, Rua dos Bragas n° 289, 4050-123 Porto, Portugal; Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), and Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal.
authors.forename: Honorina
authors.initials: H
authors.lastname: Cidade
authors.affiliation: Laboratório de Microbiologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal; Cancer Drug Resistance Group, IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Rua Doutor Roberto Frias, 4200 Porto, Portugal.
authors.forename: M Helena
authors.initials: MH
authors.lastname: Vasconcelos
authors.affiliation: REQUIMTE, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal; Laboratório de Microbiologia, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira no. 228, 4050-313 Porto, Portugal. Electronic address: lucilia.saraiva@ff.up.pt.
authors.forename: Lucília
authors.initials: L
authors.lastname: Saraiva
mesh_terms: D001681:Biological Assay; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism*; D053179:Caspase 7 / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects*; D020536:Enzyme Activators / Q000737:chemistry / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology; D047309:Flavones / Q000737:chemistry / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D061986:MCF-7 Cells; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development
chemical_list: C000592146:3-hydroxy-7-geranyloxyflavone; C000592145:5,6-dihydroxy-7-prenyloxyflavone; D020536:Enzyme Activators; D047309:Flavones; D005047:Etoposide; D053148:Caspase 3; D053179:Caspase 7
keywords: Caspase-3; Caspase-7; Caspase-7 activators; Prenylated flavonoids; Target-based screening assays; Yeast