Several clonal lines of cultured Leydig
tumor cells have been established and characterized in terms of
gonadotropin receptors and
steroid production. Although freshly isolated cells derived from the M5480P
tumor have functional
hCG receptors, only two of the five clonal lines established were shown to bind significant quantities of hCG. In these clones,
steroid production can be stimulated to the same extent by hCG,
cholera toxin, and 8-Br-cAMP. The other three clones bind a small amount of hCG and respond to the
hormone with a marginal increase in steroidogenesis.
Steroid production, however, is significantly stimulated by
cholera toxin or 8-Br-cAMP. A comparison of the
steroids produced by freshly isolated cells and two of the clones revealed some changes in the steroidogenic pathway. The most obvious change is an increase in the ability of the cultured cells to synthesize
20 alpha-dihydroprogesterone (20 alpha-hydroxypregn-4-en-3-one). These clonal lines may provide a suitable model system for the study of
gonadotropin actions and regulation of the expression of differentiated functions of Leydig cells.