PITTSBURGH — Four charitable foundations have dropped their 60-day option to buy Pittsburgh's first public radio station, WDUQ-FM.

Duquesne University has owned the 90.5 FM frequency since 1949, but no longer wants to spend $500,000 annually to subsidize it. The Heinz Endowments, The Pittsburgh and Richard King Mellon foundations, and a fourth anonymous charity paid $50,000 for a 60-day option to buy the station that expires July 2.