Three-Dimensional Proteome-Wide Scale Screening for the 5‑Alpha Reductase Inhibitor Finasteride: Identification of a Novel Off-Target

Finasteride, a 5-alpha
reductase (5α-R) inhibitor, is a widely
used drug for treating androgen-dependent conditions. However, its
use is associated with sexual, psychological, and physical complaints,
suggesting that other mechanisms, in addition to 5α-R inhibition,
may be involved. Here, a multidisciplinary approach has been used
to identify potential finasteride off-target proteins. SPILLO-PBSS
software suggests an additional inhibitory activity of finasteride
on phenylethanolamine N-methyltransferase (PNMT),
the limiting enzyme in formation of the stress hormone epinephrine.
The interaction of finasteride with PNMT was supported by docking
and molecular dynamics analysis and by in vitro assay,
confirming the inhibitory nature of the binding. Finally, this inhibition
was also confirmed in an in vivo rat model. Literature
data indicate that PNMT activity perturbation may be correlated with
sexual and psychological side effects. Therefore, results here obtained
suggest that the binding of finasteride to PNMT might have a role
in producing the side effects exerted by finasteride treatment.