  We calculate differential energy spectra ($x_F$-distributions) of charmed
particles produced in proton-nucleus collisions, assuming the existence of
intrinsic heavy quark components in the proton wave function. For the
calculation, the recently proposed factorization scheme is used, based on the
Color Glass Condensate theory and specially suited for predictions of a
production of particles with large rapidities. It is argued that the intrinsic
charm component can, if it exists, dominate in a sum of two components,
intrinsic + extrinsic, of the inclusive spectrum of charmed particles produced
in proton-nucleus collisions at high energies, in the region of medium $x_F$,
$0.15 < x_F < 0.7$, and can give noticeable contribution to atmospheric fluxes
of prompt muons and neutrinos.
