[Hormone dependence of malignant ovarian tumors--an in vitro model].

The steroid hormone receptor content of 32 malignant ovarian tumors was compared with the in vitro effectiveness of 4 hydroxytamoxifen (OH-TAM) and medroxy-progesterone acetate (MPA) tested in the Human Tumor Colony Forming Assay (HTCFA). The sensitivity for the receptor determination was 5 fmol/mg cytosol protein. Estrogen receptors (ER) and progesterone receptors (PR) were found in 15 (47%) and 13 (41%) of the tumors respectively. As standard criteria for the HTCFA, a minimum of 30 colonies with a diameter of more than 60 microns and 100 microns was used in the control group. The in-vitro sensitivity of ovarian tumors to OH-TAM and MPA was independent on the ER or PR content, and amounted to 9% for OH-TAM and 6% for MPA. However, all 12 ER-PR-tumors proved resistant to OH-TAM and MPA. 18 ovarian tumors showed a sufficient colony growth, even in the size class exceeding 100 microns. With a minimum colony size of 60 microns and 100 microns, 17% and 33% respectively were sensitive to OH-TAM. A similar effect on the proliferative capacity of the Tumor Colony Forming Units (TCFUs), unrelated to PR, was observed with MPA. Dependent on colony size, we found an increasing sensitivity against MPA from 11% to 22%. The in-vitro effectiveness of both OH-TAM and MPA in the clonogenic assay of malignant ovarian tumors was certainly not as potent as suggested by the results obtained in biochemical steroid hormone receptor analysis. To prove the hormonal response in the HTCFA, it is necessary to determine number and size of the colonies as an expression of their proliferative potential.