Pacific Office Properties Trust Inc., the owner of seven Honolulu office buildings, plans to sell one of them — First Insurance Center — to a Massachusetts company that owns close to 400 properties nationwide.

San Diego-based Pacific Office, which was founded by local commercial real estate investor Jay Shidler, announced today it has an agreement to sell the building to Newton, Mass.-based Senior Housing Properties Trust for $70.5 million.

The sale price includes the assumption of $52 million of debt secured by the 11-story building on the makai-ewa corner of Ward Avenue and Beretania Street.

The transaction is expected to close by June 30.