A new laboratory building shared by the Harvard Medical School, a Harvard-affiliated hospital and a private medical research institute was named in honor of a former Med School professor at ceremonies last night.

The Med School, Brigham and Women's Hospital and the Howard Hughes Medical Institute began planning the George W. Thorn Building for Medical Research in 1980. Construction on the 16-story medical area structure began in 1983 and was opened in October.

"The philosophy behind the joint project was that the three organizations would collaborate to construct the building so that their researchers could then collaborate with each other," according to a statement released yesterday by the Medical School.

The building was dedicated last night in Boston at a formal dinner hosted by the Hughes Institute. Thorn, an endocrinologist, is also a retired chief of medicine at Brigham and Women's and the chairman of the Hughes Institute board of trustees.

The Med School Genetics Department, chaired by Dr. Philip Leder, occupies four floors of the new building. Leder's research currently focusses on the role genes play in causing cancer.

One Dozen Researchers

The Hughes Institute, which was founded in 1953 by industrialist Howard Hughes, has space in the new building for about a dozen investigators studying hematology and endocrinology. Brigham and Women's occupies nine and one-half floors.