Stimulation of N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate of ectopic production of the free beta subunit of chorionic gonadotropin by a human brain tumor cell line.

Previous studies have favored a basic difference in the regulation of specialized protein production by cells derived from the usual tissue of origin (eutopic) and cancer cells derived from a tissue not normally producing the protein (ectopic). Thus N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate was believed to stimulate only eutopic (but not ectopic) chorionic gonadotropin production, and butyrate to stimulate only ectopic (but not eutopic). However, in CBT, a human brain tumor cell line, we find that N6,O2'-dibutyryl cyclic adenosine 3':5'-monophosphate, but not butyrate, stimulated ectopic production of the beta subunit of chorionic gonadotropin. We conclude that neither butyrate nor cyclic adenosine 3':5'-monophosphate derivatives reliably discriminate ectopic from eutopic regulation.