New York (Reuters) - Dubai World said on Wednesday it will invest up to USD 5.2 billion in MGM Mirage by buying shares and half of a major Las Vegas project, making the state-owned investment firm a major player in the biggest gambling destination in the United States. MGM shares jumped as much as 10.5 percent and its bonds rallied on the pending USD 3.9 billion cash infusion stemming from the deal, as well as the premium Dubai offered for the shares.