New pyrrole-based histone deacetylase inhibitors: binding mode, enzyme- and cell-based investigations.
Aroyl-pyrrolyl-hydroxy-amides (APHAs) are a class of synthetic HDAC inhibitors described by us since 2001. Through structure-based drug design, two isomers of the APHA lead compound 1, the 3-(2-benzoyl-1-methyl-1H-pyrrol-4-yl)-N-hydroxy-2-propenamide 2 and the 3-(2-benzoyl-1-methyl-1H-pyrrol-5-yl)-N-hydroxy-2-propenamide 3 (iso-APHAs) were designed, synthesized and tested in murine leukemia cells as antiproliferative and cytodifferentiating agents. To improve their HDAC activity and selectivity, chemical modifications at the benzoyl moieties were investigated and evaluated using three maize histone deacetylases: HD2, HD1-B (class I human HDAC homologue), and HD1-A (class II human HDAC homologue). Docking experiments on HD1-A and HD1-B homology models revealed that the different compounds selectivity profiles could be addressed to different binding modes as observed for the reference compound SAHA. Smaller hydrophobic cap groups improved class II HDAC selectivity through the interaction with HD1-A Asn89-Ser90-Ile91, while bulkier aromatic substituents increased class I HDAC selectivity. Taking into account the whole enzyme data and the functional test results, the described iso-APHAs showed a behaviour of class I/IIb HDACi, with 4b and 4i preferentially inhibiting class IIb and class I HDACs, respectively. When tested in the human leukaemia U937 cell line, 4i showed altered cell cycle (S phase arrest), joined to high (51%) apoptosis induction and significant (21%) differentiation activity.
Dipartimento di Studi Farmaceutici, Sapienza Università di Roma, 00185 Roma, Italy. antonello.mai@uniroma1.it
Antonello
A
Mai
Sergio
S
Valente
Angela
A
Nebbioso
Silvia
S
Simeoni
Rino
R
Ragno
Silvio
S
Massa
Gerald
G
Brosch
Floriana
F
De Bellis
Fabio
F
Manzo
Lucia
L
Altucci
D017209:Apoptosis; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000737:chemistry* / Q000494:pharmacology*; D008958:Models, Molecular; D011487:Protein Conformation; D011758:Pyrroles / Q000737:chemistry* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D020298:U937 Cells
D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D011758:Pyrroles; D006655:Histone Deacetylases