Rounding of cultured human carcinoid tumor cells by forskolin.

A primary culture of carcinoid cells obtained from a metastasized brain tumor of a 30 year old man was established. Rounding of carcinoid cells was induced by the addition of 20 microM forskolin or 1 mM dibutyryl cyclic AMP to the culture medium. The cyclic AMP content in carcinoid cells was increased thirtyfold by the addition of 20 microM forskolin. The results provided evidence that cyclic AMP might also be involved in rounding of human malignant carcinoid cells.