LONDON (AP) — Filmmaker James Cameron and Titanic discoverer Robert Ballard are backing a bid by a group of British museums to acquire a collection of 5,500 artifacts from the sunken vessel. The campaign announced Tuesday aims to raise $20 million (15 million pounds) to buy the items from a private American company that salvaged them from the wreck. The director of the 1997 blockbuster "Titanic," starring Leonardo DiCaprio and Kate Winslet, said there are grave concerns that the collection will be broken up and sold privately because that company has filed for bankruptcy.