пиар IS direct sounding of "PR (public relations)".
пиар (noun) (PR, example: "черный пиар")
пиарить (imperfect verb) (to promote)
попиарить (perfect verb) (to do promotion some time (action has beginning and ending))
пропиарить (perfect verb) (to make promotion (complete/successful action))
пропиаренный (adjective) (promoted)