11 research outputs found
Unveiling a novel transient druggable pocket in BACE-1 through molecular simulations: conformational analysis and binding mode of multisite inhibitors
The critical role of BACE-1 in the formation of neurotoxic Ă-amyloid peptides in the brain makes it an attractive target for an efficacious treatment of Alzheimerâs disease. However, the development of clinically useful BACE-1 inhibitors has proven to be extremely challeng- ing. In this study we examine the binding mode of a novel potent inhibitor (compound 1, with IC50 80 nM) designed by synergistic combination of two fragmentsâhuprine and rheinâ that individually are endowed with very low activity against BACE-1. Examination of crystal structures reveals no appropriate binding site large enough to accommodate 1. Therefore we have examined the conformational flexibility of BACE-1 through extended molecular dynamics simulations, paying attention to the highly flexible region shaped by loops 8â14, 154â169 and 307â318. The analysis of the protein dynamics, together with studies of pocket druggability, has allowed us to detect the transient formation of a secondary binding site, which contains Arg307 as a key residue for the interaction with small molecules, at the edge of the catalytic cleft. The formation of this druggable âfloppyâ pocket would enable the bind- ing of multisite inhibitors targeting both catalytic and secondary sites. Molecular dynamics simulations of BACE-1 bound to huprine-rhein hybrid compounds support the feasibility of this hypothesis. The results provide a basis to explain the high inhibitory potency of the two enantiomeric forms of 1, together with the large dependence on the length of the oligo- methylenic linker. Furthermore, the multisite hypothesis has allowed us to rationalize the inhibitory potency of a series of tacrine-chromene hybrid compounds, specifically regarding the apparent lack of sensitivity of the inhibition constant to the chemical modifications intro- duced in the chromene unit. Overall, these findings pave the way for the exploration of novel functionalities in the design of optimized BACE-1 multisite inhibitors
The role of stem cell transplantation in the management of relapsed follicular lymphoma in the era of targeted therapies
Patients with relapsed follicular lymphoma (FL) following first-line therapy have an increasing number of management strategies ranging from observation through to stem cell transplantation. There has been an exciting expansion in novel agents to treat FL, but at present there is not a universally accepted standard of care in the relapse setting. Decision-making can be difficult for the clinician as there is a paucity of data to compare the various relapse therapies available. This review will discuss conventional therapy for relapsed FL, consider the use of novel agents and explore the role and timing of autologous and allogeneic stem cell transplantation