Effect of sildenafil on human aromatase activity: From in vitro structural analysis to catalysis and inhibition in cells.
Aromatase catalyses the conversion of androgens into estrogens and is a well-known target for breast cancer therapy. As it has been suggested that its activity is affected by inhibitors of phosphodiesterase-5, this work investigates the potential interaction of sildenafil with aromatase. This is carried out both at molecular level through structural and kinetics assays applied to the purified enzyme, and at cellular level using neuronal and breast cancer cell lines. Sildenafil is found to bind to aromatase with a KDof 0.58±0.05μM acting as a partial and mixed inhibitor with a maximal inhibition of 35±2%. Hyperfine sublevel correlation spectroscopy and docking studies show that sildenafil binds to the heme iron via its 6th axial water ligand. These results also provide information on the starting molecular scaffold for the development of new generations of drugs designed to inhibit aromatase as well as phosphodiesterase-5, a new emerging target for breast cancer therapy.
Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy.
Roberta
R
Baravalle
Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy.
Francesca
F
Valetti
Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy.
Gianluca
G
Catucci
Department of Clinical and Biological Sciences, University of Torino, Regione Gonzole, 10-10043 Orbassano, Italy.
Giovanna
G
Gambarotta
Department of Chemistry, University of Torino, via Pietro Giuria 7, 10125, Torino, Italy.
Mario
M
Chiesa
Department of Chemistry, University of Torino, via Pietro Giuria 7, 10125, Torino, Italy.
Sara
S
Maurelli
Department of Chemistry, University of Torino, via Pietro Giuria 7, 10125, Torino, Italy.
Elio
E
Giamello
Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, CS, Italy.
Ines
I
Barone
Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, CS, Italy.
Stefania
S
Catalano
Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, CS, Italy.
Sebastiano
S
Andò
Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy; CrisDi, Interdepartmental Center for Crystallography, via Pietro Giuria 7, 10125, Torino, Italy. Electronic address: giovanna.dinardo@unito.it.
Giovanna
G
Di Nardo
Department of Life Sciences and Systems Biology, University of Torino, via Accademia Albertina 13, 10123 Torino, Italy; CrisDi, Interdepartmental Center for Crystallography, via Pietro Giuria 7, 10125, Torino, Italy. Electronic address: gianfranco.gilardi@unito.it.
Gianfranco
G
Gilardi
D001141:Aromatase / Q000378:metabolism*; D047072:Aromatase Inhibitors / Q000737:chemistry*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism; D002384:Catalysis; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D006418:Heme / Q000737:chemistry; D006801:Humans; D020128:Inhibitory Concentration 50; D007501:Iron / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D061986:MCF-7 Cells; D062105:Molecular Docking Simulation; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry; D000068677:Sildenafil Citrate / Q000737:chemistry*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
D047072:Aromatase Inhibitors; D008024:Ligands; D011994:Recombinant Proteins; D014867:Water; D006418:Heme; D000068677:Sildenafil Citrate; D007501:Iron; D001141:Aromatase; C561410:CYP19A1 protein, human; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5
Aromatase inhibitors; Breast cancer; Cytochromes P450; Estrogens; Sildenafil