[In vivo and in vitro effects of GnRH analogs on ovarian Leydig cell tumor]

A 65-year old patient, suspected to be suffering from an androgen producing ovarian tumour, was treated preoperatively with the GnRH agonist triptorelin (500 micrograms/day s.c.) for 7 days. After an initial rise, gonadotrophin levels were suppressed under this treatment. The elevated serum testosterone concentrations were reduced by approx. 50% by the triptorelin injections. After the extirpation of the tumour (histologically a Leydig cell tumour of the ovary without signs of malignancy), primary cell cultures which secreted testosterone and androstenedione were prepared. Coincubation of the tumour cells with the GnRH agonist triptorelin had no effect on their androgen secretion. Treatment of the tumour cells with high concentrations (10(-5) M) of a GnRH antagonist, however, resulted in a 100% increase of their testosterone and androstenedione secretion. GnRH-binding sites of low affinity (Ka = 0.54 x 10(5) M-1) and high capacity (B max = 1364 x 10(-12) M/mg membrane protein) were identified in the tumour. These findings suggest that GnRH analogues might modify androgen secretion of sex-cord stromal tumours of the ovary via the suppression of endogenous gonadotrophin secretion and possibly also via direct effects on the tumour cells.