Simplify the following text for a Grade 8 native English-speaking person.
Original: Cecil B. DeMille cast her as the Roman empress Poppaea in his historical epic , The Sign of the Cross ( 1932 ) , opposite Fredric March .
Simplified: Colbert 's career got a huge boost when Cecil B. DeMille cast her as the Roman empress Poppaea in his historical epic The Sign of the Cross ( 1932 ) , opposite Fredric March and Charles Laughton ( as Nero ) .