Cessation of steroidogenesis in leydig cell tumors after removal of luteinizing hormone and adenosine cyclic 3',5'-monophosphate

Abstract

Luteinizing hormone (LH), but not follicle-stimulating hormone or prolactin, was shown to enhance steroid synthesis of Leydig tumor cells in vitro. Adenosine cyclic 3',5'-monophosphate (cAMP) duplicated the effect of LH. Removal of LH from the medium within 1 hour of incubation by washing the cells had no effect on the rate of steroid synthesis previously stimulated by LH. Under these conditions, addition of LH antiserum was required to reduce steroid synthesis. In contrast, removal of cAMP by washing the tumor cells caused a rapid termination of the previously induced steroidogenesis. Cycloheximide reduced the steroid synthesis initiated by LH. These results suggest that (a) steroidogenesis may be controlled by short lived factors (proteins), (b) LH may be required continually to elevate cAMP levels to maintain steroid synthesis at stimulated rates, and (c) that LH is probably bound to the tumor cells.