Binding of [3H] monohydroxytamoxifen in ovarian carcinoma

Intracellular actions of steroid hormones and their therapeutic value, including the potential of radiohalosteroids against ovarian cancer

The biological activities of steroid hormones are effected via intracellular receptors. The receptors are part of a ligand-activated family of transcription regulator proteins that are critical for steroid-regulated cell differentiation. With recombinant cDNA technology, yeast and cultured animal cells can be made to express mammalian cDNA steroid receptors from cDNA clones that contain deletions and substitutions. Among the leading problems addressed in these models is the characterization of sequences that promote association or interaction with other transcription regulating molecules, including oncogene products. Recently it has been found that heat shock proteins may serve not only to stabilize the receptor proteins but also to precondition the activation imparted by ligand binding. Aberrant receptor proteins can be found in ovarian cancer. Whether aberrant receptor proteins are associated with transformation in general or with a variable clinical response to steroidal or anti-steroidal therapy is not known. Even after chemotherapy, steroid receptors are expressed in the metastases of ovarian cancers seen clinically, and they may have potential uses for localization and treatment of receptor-rich cancers. Radioligand pharmaceuticals appropriate for imaging or for site-directed radiocytotoxicity can be sequestered to the nuclei of receptor-rich cancers. Initial clinical imaging and therapy trials with such pharmaceuticals have been approved and begun. In the use of halogenated estrogen radiopharmaceuticals, liver metabolism and enterohepatic recirculation are important considerations. Ascites prolongs retention of a radiohalogenated estrogen in the abdominal cavity. Distant metastases have been localized with [123I]-estrogen in breast cancer patients in pre-operative procedures. Receptor-mediated cytotoxicity occurs when estrogen receptor radioligand pharmaceuticals that are Auger electron emitters are used in vitro.

Biodistribution, with high uptake by the reproductive tract, of an intraperitoneally infused radiohalogenated steroidal estrogen-receptor ligand

We infused [123I]16 alpha-(123I)-iodo-estradiol ([123I]E2) intraperitoneally (i.p.) into swine to study its biodistribution and to explore the i.p. use of radiohalogenated steroid estrogen-receptor (ER) ligands as a potential option for diagnosing and treating intra-abdominal, retroperitoneal, and distant sites of advanced ER-rich malignancies. Fifty to 80% of the radiolabel was absorbed from the peritoneal cavity within 30 minutes, and 30 to 50% of the infused radiolabel was excreted in the urine within 2 hr. The rate of biliary clearance was maximal within 25 minutes. At 3 hr, the ER-rich reproductive tract had greater than 63 times the concentration of radiolabel in blood; the former was blocked by non-labeled competitors for ER. Uptake by non-ER-rich tissues, compared to blood, ranged from 0.7:1 (heart and lungs) to 16:1 (spleen); the omentum, however, exhibited a concentration as high as 64:1, which was not blocked by non-labeled ER ligands. Uptake by ER-rich target tissue remained high when charcoal was used to prevent reabsorption of radiolabel from the digestive tract after its biliary excretion, and when the products of biliary excretion were removed by catheterization of the common bile duct. Neither charcoal nor exteriorization of bile appeared to affect urinary clearance of the radiolabel over the time course of the experiments. Taken together with the recent development of syntheses that yield radiohalogenated sex steroid receptor ligands of high specific activity, our findings are encouraging for the potential application of radiolabeled ligands as i.p. administered pharmaceuticals. The advantage of the i.p. route is that it provides direct uptake of the pharmaceutical by free-floating clusters and individual cancer cells in ascitic fluid, as well as delivery via the circulation to vascularized intra- and/or extraperitoneal metastases.

Characterization of a human ovarian carcinoma cell line with estrogen and progesterone receptors

The potential significant therapeutic and prognostic roles for the sex steroid receptors in ovarian cancer are recognized. The authors present in detail the biochemical, morphologic, cytogenetic, and growth characteristics of an ovarian carcinoma cell line, BG-1, which has functional estrogen and progesterone receptors (23 and 300 fmol/mg protein, respectively) in clinically significant levels. In particular, BG-1 has a DNA index of 1.14, a stable karyotype with specific translocations, and produces and secretes CA 125 into the media.

Growth patterns and hormonal sensitivity of primary tumor, abdominal metastasis and ascitic fluid from human epithelial ovarian carcinomas in the tumor colony-forming assay

The human tumor colony forming assay was used to evaluate the response of ovarian carcinoma cells from primary tumors, ascitic fluids and metastasis to hormonal treatment. In 12/35 patients a sufficient colony formation (greater than 30 colonies/dish) was obtained in order to perform a simultaneous drug testing. The plating efficiency of the metastatic samples (0.12%) was significantly higher (P less than 0.053) than those from the primary tumor (0.076%) or those that were derived from the ascitic fluid (0.082%). Colonies from the metastatic tissues could be evaluated 2-4 days earlier than those from primary tumors. These discrepancies may be due to a heterogeneity in the clonable tumor cell compartment of primary tumor and metastasis. The antiproliferative properties of the antiestrogen tamoxifen and the progestin gestoneron were studied. In 9/12 cases a significant, dose-dependent reduction of colony formation (greater than 70-90% of the controls) was observed after continuous exposure to 1 mumole tamoxifen. No correlation between the dose response and the content of steroid receptors was found. Even estrogen receptor negative tumor samples showed a maximal antiproliferative effect of tamoxifen.