Complex sentence: She came into prominence in the early 2000s as a member of the ill-fated girl-group Eden's Crush and then was cast as the lead singer of the Pussycat Dolls, a burlesque troupe turned-recording group.
Split into simpler sentences: She came into prominence in the early 2000s as a member of the ill-fated girl-group Eden's Crush. She then was cast as the lead singer of The Pussycat Dolls, a burlesque troupe turned-recording group.