Monroe 's star grew with her acting in films such as Gentlemen Prefer Blondes , How to Marry a Millionaire , Some Like It Hot , and The Seven Year Itch . Her `` dumb blonde '' persona was used to comedic effect in such films as Gentlemen Prefer Blondes ( 1953 ) , How to Marry a Millionaire ( 1953 ) and The Seven Year Itch ( 1955 ) .