REUTERS: Five Democratic U.S. senators, including presidential candidate Bernie Sanders, told the Justice Department and Federal Communications Commission on Thursday that they had "significant concerns" about Charter Communications Inc's planned acquisition of Time Warner Cable Inc and Bright House Networks. The senators, who also included Elizabeth Warren, Ed Markey, Ron Wyden and Al Franken, said in a letter to the agencies that are reviewing the proposal that the deal would create "a nationwide broadband duopoly," with Charter and Comcast Corp in nearly two-thirds of U.S. high-speed broadband homes.