Specific low affinity binding sites for gonadotropin-releasing hormone in human endometrial carcinomata

The Role of Gonadotropin-Releasing Hormone (GnRH) in Endometrial Cancer

Endometrial cancer (EC) is one of the most common gynecological malignancies. Gonadotropin releasing hormone (GnRH) is a decapeptide first described to be secreted by the hypothalamus to regulate pituitary gonadotropin secretion. In this systematic review, we analyze and summarize the data indicating that most EC express GnRH and its receptor (GnRH-R) as part of an autocrine system regulating proliferation, the cell cycle, and apoptosis. We analyze the available data on the expression and function of GnRH-II, its putative receptor, and its signal transduction. GnRH-I and GnRH-II agonists, and antagonists as well as cytotoxic GnRH-I analogs, have been shown to inhibit proliferation and to induce apoptosis in human EC cell lines in pre-clinical models. Treatment with conventional doses of GnRH-agonists that suppress pituitary gonadotropin secretion and ovarian estrogen production has become part of fertility preserving therapy of early EC or its pre-cancer (atypical endometrial hyperplasia). Conventional doses of GnRH-agonists had marginal activity in advanced or recurrent EC. Higher doses or more potent analogs including GnRH-II antagonists have not yet been used clinically. The cytotoxic GnRH-analog Zoptarelin Doxorubicin has shown encouraging activity in a phase II trial in patients with advanced or recurrent EC, which expressed GnRH-R. In a phase III trial in patients with EC of unknown GnRH-R expression, the cytotoxic GnRH doxorubicin conjugate was not superior to free doxorubicin. Further well-designed clinical trials exploiting the GnRH-system in EC might be useful.

The spatiotemporal hormonal orchestration of human folliculogenesis, early embryogenesis and blastocyst implantation

The early reproductive events starting with folliculogenesis and ending with blastocyst implantation into the uterine endometrium are regulated by a complex interplay among endocrine, paracrine and autocrine factors. This review examines the spatiotemporal integration of these maternal and embryonic signals that are required for successful reproduction. In coordination with hypothalamic-pituitary-gonadal (HPG) hormones, an intraovarian HPG-like axis regulates folliculogenesis, follicular quiescence, ovulation, follicular atresia, and corpus luteal functions. Upon conception and passage of the zygote through the fallopian tube, the contribution of maternal hormones in the form of paracrine secretions from the endosalpinx to embryonic development declines, with autocrine and paracrine signaling becoming increasingly important as instructional signals for the differentiation of the early zygote/morula into a blastocyst. These maternal and embryonic signals include activin and gonadotropin-releasing hormone 1 (GnRH1) that are crucial for the synthesis and secretion of the 'pregnancy' hormone human chorionic gonadotropin (hCG). hCG in turn signals pre-implantation embryonic cell division and sex steroid production required for stem cell differentiation, and subsequent blastulation, gastrulation, cavitation and blastocyst formation. Upon reaching the uterus, blastocyst hatching occurs under the influence of decreased activin signaling, while the attachment and invasion of the trophoblast into the endometrium appears to be driven by a decrease in activin signaling, and by increased GnRH1 and hCG signaling that allows for tissue remodeling and the controlled invasion of the blastocyst into the uterine endometrium. This review demonstrates the importance of integrative endocrine, paracrine, and autocrine signaling for successful human reproduction.

Gonadotropin-releasing hormone: GnRH receptor signaling in extrapituitary tissues

Gonadotropin-releasing hormone (GnRH) has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in locally produced, extrapituitary GnRH. GnRH receptor (GnRHR) was found to be expressed in normal human reproductive tissues (e.g. breast, endometrium, ovary, and prostate) and tumors derived from these tissues. Numerous studies have provided evidence for a role of GnRH in cell proliferation. More recently, we and others have reported a novel role for GnRH in other aspects of tumor progression, such as metastasis and angiogenesis. The multiple actions of GnRH could be linked to the divergence of signaling pathways that are activated by GnRHR. Recent observations also demonstrate cross-talk between GnRHR and growth factor receptors. Intriguingly, the classical G(alphaq)-11-phospholipase C signal transduction pathway, known to function in pituitary gonadotropes, is not involved in GnRH actions at nonpituitary targets. Herein, we review the key findings on the role of GnRH in the control of tumor growth, progression, and dissemination. The emerging role of GnRHR in actin cytoskeleton remodeling (small Rho GTPases), expression and/or activity of adhesion molecules (integrins), proteolytic enzymes (matrix metalloproteinases) and angiogenic factors is explored. The signal transduction mechanisms of GnRHR in mediating these activities is described. Finally, we discuss how a common GnRHR may mediate different, even opposite, responses to GnRH in the same tissue/cell type and whether an additional receptor(s) for GnRH exists.

Targeting of cytotoxic luteinizing hormone-releasing hormone analogs to breast, ovarian, endometrial, and prostate cancers

Targeted chemotherapy is a modern approach aimed at increasing the efficacy of systemic chemotherapy and reducing its side effects. The peptide receptors expressed primarily on cancerous cells can serve as targets for a selective destruction of malignant tumors. Binding sites for LHRH (now known in genome and microarray databases as GNRH1), were found on 52% of human breast cancers, about 80% of human ovarian and endometrial cancers, and 86% of human prostatic carcinoma specimens. Because LHRH receptors are not expressed on most normal tissues, they represent a specific target for cancer chemotherapy with antineoplastic agents linked to an LHRH vector molecule. To test the efficacy of targeted chemotherapy based on LHRH analogs, we recently developed a cytotoxic analog of LHRH, designated AN-152, which consists of [D-Lys6]LHRH covalently linked to one of the most widely used chemotherapeutic agents, doxorubicin (DOX). In addition, we designed and synthesized a highly active derivative of DOX, 2-pyrrolino-DOX (AN-201), which is 500-1000 times more potent than DOX in vitro. AN-201 is active against tumors resistant to DOX, and noncardiotoxic. As in the case of DOX, AN-201 was coupled to carrier peptide [D-Lys6]LHRH to form a superactive targeted cytotoxic LHRH analog, AN-207. Both AN-152 and AN-207 can effectively inhibit the growth of LHRH receptor-positive human breast, ovarian, endometrial, and prostate cancers xenografted into nude mice. DOX-containing cytotoxic LHRH analog AN-152 is scheduled for clinical phase I/IIa trials in patients with advanced ovarian and breast cancers in 2005.

Evidence for different gonadotropin-releasing hormone response sites in rat ovarian and pituitary cells

The participation of type I GnRH receptor (GnRH-R) on GnRH-II-induced gonadotropin secretion in rat pituitary cells was investigated. Furthermore, we extended the study of GnRH-II action to ovarian cells. The GnRH-II was able to mobilize inositol triphosphate (IP(3)) and to induce LH and FSH release in a dose-dependent manner in pituitary cells and in a GnRH-I-like manner. The GnRH-analog 135-18 (agonist for type II GnRH-R and antagonist for type I GnRH-R) was unable to elicit any cellular response tested in these pituitary cells. The GnRH-II responses were blocked by the type I GnRH-R-antagonists CRX or 135-18, suggesting that these effects were mediated by the type I GnRH-R. In contrast to pituitary cells, GnRH-I, but not GnRH-II, elicited an IP(3) response in superovulated ovarian cells; 135-18 also had no effect. However, GnRH-II as well as GnRH-I presented antiproliferative effects on these cells. Surprisingly, 135-18 had stronger antiproliferative effects than either GnRH peptide. The 135-18 analog, but not GnRH-I or GnRH-II, increased progesterone secretion in superovulated ovarian cells. These results strongly suggest that GnRH-II is able to stimulate rat pituitary cells through the type I GnRH-R, with no evidence for the presence of type II GnRH-R. On the other hand, our results indicate a putative GnRH-R in superovulated ovarian cells with response characteristics that differ from those of the GnRH-R in the pituitary.

Conservative treatment may be beneficial for young women with atypical endometrial hyperplasia or endometrial adenocarcinoma

OBJECTIVE

To evaluate whether an alternative treatment to radical hysterectomy exists for young women with endometrial adenocarcinoma.

DESIGN

A review of the literature (70 articles) plus personal results.

SETTING

University hospital.

PATIENT(S)

Women with atypical endometrial hyperplasia or adenocarcinoma.

MAIN OUTCOME MEASURE(S)

The recurrence rate and the pregnancy rate after conservative therapy.

CONCLUSION(S)

Conservative treatment of well-differentiated stage I endometrial adenocarcinoma can be considered in young patients, with close surveillance to diagnose any possible recurrence.

Goserelin acetate as treatment for recurrent endometrial carcinoma: a Gynecologic Oncology Group study

This Gynecologic Oncology Group (GOG) study was designed to estimate the activity of goserelin acetate as treatment for advanced and recurrent endometrial carcinoma. Forty evaluable patients received monthly treatment with goserelin acetate at a dose of 3.6 mg, given subcutaneously. Standard GOG response and adverse effects criteria were used. The median age of patients was 71 years. Seventy-one percent of patients had received prior radiation therapy; 18% of patients were reported to have received prior progestational therapy for endometrial cancer. One patient had received prior chemotherapy. There were two complete responses (5%) and three partial responses (7%). One response occurred in a patient who previously did not respond to progestin therapy after having achieved a response. The overall response rate was 11% (95% CI: 4-27%). Median progression-free survival was 1.9 months and median overall survival was 7.3 months. No severe or life-threatening toxicities occurred because of goserelin. Deep venous thrombosis developed in two patients. This study confirmed the limited activity of goserelin acetate in endometrial carcinoma, with only one response in a patient previously treated with hormonal therapy. The activity is insufficient to warrant further study of the single agent at this time. Elucidation of the mechanism of action of this drug may allow more effective use in conjunction with other agents in the future.

Expression of the second isoform of gonadotrophin-releasing hormone (GnRH-II) in human endometrium throughout the menstrual cycle

We examined the expression of the protein and mRNA of the newly cloned isoform of human gonadotrophin-releasing hormone (GnRH-II) in the normal human endometrium during the menstrual cycle. Nested RT-PCR and sequence analysis revealed that two spliced variants of GnRH-II mRNA were expressed during the entire menstrual cycle, with the shorter transcript having a 21 nucleotide deletion in the region coding for GnRH-associated peptide. Using immunohistochemistry, we identified immunoreactive GnRH-II in both stromal and glandular epithelial cells during the entire menstrual phase. The immunostaining intensity was stronger during the early and mid-secretory phase compared with the proliferative and late-secretory phase. A large amount of immunoreactive GnRH-II was localized in the apical pole of the glandular lumen. Our results show that the second isoform of GnRH (GnRH-II) is expressed in the human endometrium during the entire menstrual phase. We also suggest that an increased expression of endometrial GnRH-II peptide, noted during the early and mid-secretory phase, may play an important role in human embryo implantation.

Inhibitory effect of luteinising hormone-releasing hormone analogues on human endometrial cancer in vitro

We studied the effects of luteinising hormone-releasing hormone (LHRH) agonist leuproreline (1 microM for 96 h) and LHRH antagonist cetrorelix on the cell growth of primary cultures from nine human endometrial cancers using the sulphorhodamine colorimetric test. Histological examinations and reverse transcription and polymerase chain reaction amplification (RT-PCR) for LHRH receptors were also performed. The endometrial cancers examined had a medium to high degree of proliferative activity and a low degree of apoptotic power; furthermore, they expressed the LHRH receptor RNA variably, detectable in 71% of cases. The addition of leuproreline or cetrorelix to cell cultures inhibited growth in a statistically significant way compared to untreated control cells; nevertheless, the percentage of cell growth inhibition obtained was very variable. These data suggest that LHRH analogues can exert differential inhibitory effects on the growth of endometrial cancer, which seems to be independent of the expression of specific LHRH receptors.

A multicenter phase II study with triptorelin (sustained-release LHRH agonist) in advanced or recurrent endometrial carcinoma: a French anticancer federation study

The objective of this phase II multicenter study was to assess the efficacy and tolerance of triptorelin (a sustained-release LHRH agonist) in advanced or recurrent endometrial cancer. A total of 101 monthly intramuscular injections were administered to 24 eligible patients (median number/patient = 3; range 1-12). Mainly due to progression, only 16 patients received 3 or more injections. Among the 23 evaluable patients, 1 complete and 1 partial response (response rate of 8.7%) and 5 disease stabilizations were observed, often of long duration, but never in an irradiated area or after progestogens treatment failure. Median survival for eligible patients was 7.2 months (range: 1-36 months). Only grade 1 toxicities possibly related to the treatment were observed in 4 patients. In conclusion, triptorelin was safe, well tolerated, and easily manageable, and the very low toxicity did not impair the quality of life in these patients with a very poor prognosis. Although the response rate was disappointing, several patients showed early evidence of efficacy which may be of long duration. Response rates range between 0 and 45% in different published studies. Additional studies with stricter inclusion criteria and a larger sample size are necessary to better evaluate the role of LHRH agonists in endometrial adenocarcinomas.

Independent regulation of matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-3 in human endometrial stromal cells by gonadotropin-releasing hormone: implications in early human implantation

Early human trophoblast shows dramatic invasive properties during early pregnancy. The simultaneous synthesis of matrix metalloproteinases (MMPs) and their specific tissue inhibitors (TIMPs) in both human trophoblast and decidual membranes suggests that their controlled and balanced expression is crucial for the rapid matrix remodeling and controlled invasion during early pregnancy. Recently, we have described the presence of an extrahypothalamic GnRH immunologically, biologically and chemically identical to the hypothalamic hormone in periimplantation human embryos. Moreover, the production of this decapeptide by the human trophoblast during the early stages of placentation is well documented. TIMP-1 and -3 messenger ribonucleic acid (mRNA) expression in cultured stromal cells and protein secretion into the medium were significantly decreased by GnRH agonist compared to that in control groups. Moreover, expression of TIMP-1 was affected to a greater extent than that of TIMP-3. GnRH antagonist ablated the down-regulation of TIMPs by the GnRH agonist. MMP-9 mRNA expression was not detected in the control groups or in the groups treated with GnRH analogs. Our results provide evidence that trophoblastic GnRH may play an important role in placental tissue organization and in the early embryo-maternal dialogue by enhancing trophoblast invasion through the specific inhibition of TIMPs.

Quantitative gonadotropin-releasing hormone gene expression and immunohistochemical localization in human endometrium throughout the menstrual cycle

GnRH is one of the paracrine/autocrine regulators of hCG secretion produced by the human trophoblast during pregnancy. We hypothesized that GnRH may play a role in the embryonic/endometrial dialogue during early implantation. To examine this hypothesis, we assessed GnRH and GnRH-receptor mRNA and protein expression in human endometrium throughout the menstrual cycle of premenopausal fertile patients. Quantitation of the mRNA was performed by reverse transcription (RT)-competitive polymerase chain reaction (PCR) in the presence of a competitive cDNA fragment. RT-PCR revealed that unfractioned endometrium and isolated endometrial stromal and epithelial cells express GnRH and GnRH-receptor mRNA throughout all phases of the menstrual cycle. Quantitative PCR showed a dynamic pattern in the GnRH mRNA expression throughout the cycle, with a significant increase (p < 0.05) in the secretory phase as compared to the proliferative phase. Furthermore, quantitative competitive PCR of isolated glandular and stromal cells showed higher mRNA levels (p < 0.05) in the luteal phase in both compartments. GnRH immunostaining was localized in all major compartments, with the most intense staining during the luteal phase. On the basis of these data, we suggest that during reproductive life, endometrial GnRH may play a paracrine/autocrine role in the early stages of implantation by modulating embryonic trophoblastic secretion of hCG.

Immunoreactive gonadotropin-releasing hormone expression in cycling human endometrium of fertile patients

OBJECTIVE

To investigate the protein expression of GnRH in the endometrium of fertile patients throughout the menstrual cycle.

DESIGN

Prospective longitudinal study.

SETTING

Department of Gynecology and Obstetrics, Reproductive Immunology Laboratory, Stanford University Medical Center.

PATIENT(S)

Twenty-two fertile premenopausal women submitted to laparoscopic surgery for benign gynecologic indications. None of the 22 women had endometriosis or pelvic inflammatory disease.

INTERVENTION(S)

An endometrial biopsy specimen using the Novak curette was obtained at the time of surgery.

MAIN OUTCOME MEASURE(S)

Protein expression and localization from unfractioned endometrial tissue was analyzed by immunohistochemistry.

RESULT(S)

Gonadotropin-releasing hormone is expressed at the protein level in both the endometrial stroma and epithelium throughout the entire menstrual cycle of fertile women. Immunostaining in the human epithelium reached maximal levels in the midluteal phase and was elevated in the stroma throughout the entire luteal phase.

CONCLUSION(S)

Our results demonstrate the presence of GnRH in the human endometrium at the protein level throughout the entire menstrual cycle of fertile women, with an increase in the luteal phase compared with the preovulatory endometrium.

Effects of LHRH-analogues on mitogenic signal transduction in cancer cells

The expression of luteinizing hormone-releasing hormone (LHRH) and its receptors has been demonstrated in a number of human malignant tumors, including cancers of the breast, ovary, endometrium and prostate. These findings suggest the presence of an autocrine regulatory system based on LHRH. Recent studies in our laboratory have demonstrated that the function of LHRH produced by ovarian cancer cells is the inhibition of their proliferation. Dose-dependent antiproliferative effects of LHRH-agonists have been observed by several laboratories in cell lines derived from the above cancers. Interestingly, also LHRH-antagonists have marked antiproliferative activity in most of the ovarian, breast and endometrial cancer cell lines tested so far, indicating that the dichotomy of LHRH-agonists/LHRH-antagonists is not valid for the LHRH-system in cancer cells. In addition, our data suggest that the classical LHRH receptor signal transduction mechanisms known from the pituitary (phospholipase-C, protein kinase C, adenylyl cyclase) are not involved in the mediation of LHRH effects in cancer cells. Data obtained by several groups, including ours, rather suggest that LHRH analogs interfere with the signal transduction of growth-factor receptors and related oncogene products associated with tyrosine-kinase activity. The mechanism of action is probably an LHRH-induced activation of a phosphotyrosine phosphatase, counteracting the effects of receptor associated tyrosine kinase. In our hands, LHRH analogs virtually blocked the EGF-induced MAP-kinase activity of ovarian and endometrial cancer cells. The pharmacological exploitation of this mechanism might provide promising new therapies for these cancers.

Involvement of annexin V in antiproliferative effects of gonadotropin-releasing hormone agonists on human endometrial cancer cell line

We studied the involvement of annexin V in the antiproliferative effects of gonadotropin-releasing hormone (GnRH) agonists on human endometrial cancer cell line HHUA. HHUA cell line expressed mRNA for GnRH receptors as assessed by reverse transcriptase-PCR with oligonucleotide primers. In the presence of buserelin, the proliferation of this cell line was significantly (P < 0.01) reduced to 60% of control after 72 hr. Peak intracellular concentrations of annexin V, equivalent to about twice the control value, were obtained after 48 hr exposure to buserelin. Intracellular annexin V concentration was increased not only by buserelin, but also by protein kinase C (PKC) activator. However, there was no increase in intracellular annexin V concentration when cells were incubated with PKC inhibitor before the addition of buserelin. The results suggest that GnRH agonists inhibit cell proliferation by increasing intracellular concentrations of annexin V, an effect mediated by the activation of PKC.

Gonadotropin-releasing hormone receptor in gynecologic tumors. Frequent expression in adenocarcinoma histologic types

BACKGROUND

Gonadotropin-releasing hormone (Gn-RH) analogs have been used in the therapy of the endocrine-dependent cancers. The authors attempted to determine the frequency with which Gn-RH receptor (Gn-RHR) is present in gynecological cancers.

METHODS

Experiments were performed on gynecologic tumors that had been surgically removed and their cloned cell lines. Gn-RHR was characterized by [3H]Gn-RH binding to plasma membrane preparations. Gn-RHR messenger ribonucleic acid was determined by reverse transcription-polymerase chain reaction using oligonucleotide primers synthesized according to the published human Gn-RHR sequence.

RESULTS

High affinity binding sites with nanomolar range of Kd and Gn-RHR mRNA were detected in a high proportion (over 90%) of the specimens from endometrium (6 of 6) and endometrial carcinomas (16 of 17), myometrium (6 of 6) and myomas (4 of 5), epithelial carcinoma (21 of 23), and stromal tumors (3 of 3) of the ovary. There was no substantial Gn-RHR in cervical carcinomas or germ cell-derived tumors of the ovary. Cloned cell lines gave identical results to those obtained in their respective mother tumors.

CONCLUSIONS

We detected Gn-RHR in a wide range of the carcinomas and tissues originating from the endometrium and ovary, but not in the uterine cervix or germ cell-derived tumors. The expression of Gn-RH receptor raises the possibility that Gn-RH may play a direct regulatory role in the growth of these carcinomas, and provides a possible point of attack for therapeutic approaches using Gn-RH analogs in these malignancies.

Direct growth inhibition of human endometrial cancer cells by the gonadotropin-releasing hormone antagonist SB-75: role of apoptosis

OBJECTIVE

Our objective was to study the direct action of the gonadotropin-releasing hormone antagonist SB-75 and the agonist buserelin on the proliferation of endometrial cancer cells.

STUDY DESIGN

Two human endometrial cell lines that differ in histologic subtype and estrogen receptor content were treated with gonadotropin-releasing hormone analog. We measured the number of viable cells, cell cycle parameters, and apoptotic processes.

RESULTS

Growth of the Ishikawa cells was inhibited by SB-75 in a dose-dependent manner. 17 beta-Estradiol partially abolished the inhibitory effect of SB-75. The growth of the HEC-1A cells was not affected by the antagonist. Neither endometrial cancer cell line showed significant sensitivity to the agonist buserelin. Tenfold concentration of the gonadotropin-releasing hormone agonist did not abolish the inhibitory effect of the antagonist on cell growth. The growth inhibition was not associated with any change in cell cycle parameters but was associated with an induction of apoptosis.

CONCLUSION

The gonadotropin-releasing hormone antagonist SB-75 directly inhibits the growth of some human endometrial cancer cells and thus may be suitable for the treatment of endometrial tumors.

Failure to detect gonadotrophin-releasing hormone receptors in human benign and malignant breast tissue and in MCF-7 and MDA-MB-231 cancer cells

We have measured the binding of radiolabelled analogues of gonadotrophin-releasing hormone (GnRH) to homogenates of human breast cancer and benign breast tissue, and to MCF-7 and MDA-MB-231 cell lines. Although incubation of breast cancer homogenates with the 125I-labelled GnRH agonist analogues, buserelin [(D-Ser tBU6)GnRH 1-9 ethylamide] and tryptorelin [(D-Trp6) GnRH 1-9 ethylamide] appeared to show significant though low, specific GnRH agonist binding in a high proportion of breast cancers (32/42 for buserelin; 15/32 for tryptorelin) and benign breast tissues (13/16 for buserelin; 10/12 for tryptorelin), after correction for displaceable binding in control assay tubes, GnRH agonist binding to breast tissue was no longer apparent. The lack of specific binding was not due to inactivation of GnRH agonist tracers, as > 86% of the unbound tracer was still capable of rebinding to fresh placental membranes after incubation with breast cancer homogenates. GnRH agonist did not bind to MCF-7 and MDA-MB-231 cells, however GnRH agonist tracer inactivation following exposure to these cells was very high. We have shown recently that human placental receptors bound salmon GnRH and chicken GnRH II as well as GnRH agonists, but not other isoforms of GnRH. However, no isoform of GnRH bound significantly to human breast tumour tissue. In summary, we could not confirm the presence of specific GnRH binding sites in homogenates and membranes from human breast tissues in this study. Low levels of apparently specific binding of GnRH agonist tracers could be accounted for entirely by displacement of tracer from assay tubes. Inability to demonstrate specific binding was not due to extensive inactivation of GnRH tracers (although this may be a factor in the failure to demonstrate GnRH binding to MCF-7 and MDA-MB-231 cell lines).

Intracellular actions of gonadotropic and peptide hormones and the therapeutic value of GnRH-agonists in ovarian cancer

During the last two decades, considerable experimental evidence has been collected indicating that epithelial ovarian cancer might be gonadotropin dependent. LH and FSH receptors have been described in some of these tumors. The proliferation of ovarian cancer cells could be stimulated in vitro by gonadotropins. Suppression of endogenous LH and FSH secretion by GnRH-agonist treatment inhibited the growth of experimental or heterotransplanted ovarian cancers in various animal models. A number of recent phase II clinical trials have shown that the application of GnRH-agonists can lead to remission or stable disease in patients with relapsed advanced ovarian cancer. At present, prospective controlled clinical studies are being performed to assess the efficacy of GnRH-agonist treatment in addition to conventional surgical and cytostatic therapy in ovarian cancer in FIGO stages III and IV. Also, direct effects of GnRH analogues on ovarian cancer seem possible: a GnRH-like protein has been found in the human ovary. Our group discovered and partially characterized a specific GnRH-binding site (mol. wt 63.2 kDa) in ovarian cancer which is very similar to other human extrapituitary GnRH-binding sites of the low affinity, high capacity type, e.g. in breast cancer or the placenta. Recently, other groups have described also high affinity GnRH-agonist binding sites in ovarian cancer as well as in other extrapituitary tissues. First results from our laboratory indicate that the proliferation of certain ovarian cancer cell lines in vitro is reduced by both agonistic and antagonistic analogues of GnRH. Other authors were able to inhibit gonadotropin-induced in vitro proliferation of ovarian cancer cell lines by co-incubation with a GnRH-agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of endometrial cancer with GnRH analogs

Given the small number of side effects, GnRH may be a useful and ideal drug for new therapeutic hormonal approaches in many cases of both invasive and noninvasive endometrial cancer. The hypoestrogenic state thus induced as well as a local effect may lead to pronounced regression of the tumor. Any future therapy should, however, always be tailored to meet individual needs. The use of GnRH agonists may be advocated in the following circumstances: 1. In pronounced endometrial hyperplasia and adenomatous hyperplasia (particularly relevant in those cases where hysterectomy is not desirable, e.g., in young patients who have not yet completed their families). 2. In patients with endometrial cancer where surgery is contraindicated or refused. 3. In addition to or as a substitute for radium treatment preoperatively to reduce uterine volume (myomas) to make surgery technically easier; to devitalize the tumor, stop menorrhagia, and improve anemia. 4. In advanced cases as an adjunct to radiotherapy and gestagens. It is possible that this will produce synergistic effects. 5. As adjuvant treatment (replacing gestagens?) in primary stages. 6. In relapses of endometrial cancer, refractory to conventional therapy, and in pulmonary metastases.