NEW YORK CITY — Insurance and investment holding company C.V. Starr & Co. has signed a long-term lease for 141,000 square feet of office space at 399 Park Ave. in New York City. The company plans to use the space as its new world headquarters. It already occupies a full floor of the building but will now occupy three full floors, relocating employees from other New York-area offices to the new space. John Picco, David Stockel, August DiRenzo and Andrew Behymer of Cushman & Wakefield represented C.V. Starr in lease negotiations. The landlord, Boston Properties, was represented in-house by Andrew Levin and by CB Richard Ellis' Peter Turchin, John Powers and Greg Rothkin.