A new treatment for endometrial cancer with gonadotrophin releasing-hormone analogue

Comparative transcriptome analysis between patient and endometrial cancer cell lines to determine common signaling pathways and markers linked to cancer progression

The rising incidence and mortality of endometrial cancer (EC) in the United States calls for an improved understanding of the disease's progression. Current methodologies for diagnosis and treatment rely on the use of cell lines as models for tumor biology. However, due to inherent heterogeneity and differential growing environments between cell lines and tumors, these comparative studies have found little parallels in molecular signatures. As a consequence, the development and discovery of preclinical models and reliable drug targets are delayed. In this study, we established transcriptome parallels between cell lines and tumors from The Cancer Genome Atlas (TCGA) with the use of optimized normalization methods. We identified genes and signaling pathways associated with regulating the transformation and progression of EC. Specifically, the LXR/RXR activation, neuroprotective role for THOP1 in Alzheimer's disease, and glutamate receptor signaling pathways were observed to be mostly downregulated in advanced cancer stage. While some of these highlighted markers and signaling pathways are commonly found in the central nervous system (CNS), our results suggest a novel function of these genes in the periphery. Finally, our study underscores the value of implementing appropriate normalization methods in comparative studies to improve the identification of accurate and reliable markers.

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.

Chemotherapy for Endometrial Cancer in Adjuvant and Advanced Disease Settings

: Level I evidence exists for use of adjuvant chemotherapy in stage IIIC endometrial cancer (positive lymph nodes), although results of randomized trials have varied. Chemotherapy is also often recommended for high-risk subsets of stage I disease, such as serous carcinomas, although prospective trial data to validate this practice are lacking. Carboplatin plus paclitaxel is the current standard regimen, based on extrapolation of data from the metastatic setting. Several clinical trials have compared adjuvant pelvic radiotherapy alone to a combination of radiotherapy and chemotherapy with mixed results. One of the largest of these trials, Postoperative Radiation Therapy in Endometrial Carcinoma 3 (PORTEC-3), has completed accrual and is awaiting data maturation. Metastatic disease is not curable. For tumors of low-grade endometrioid histology with a prolonged time to recurrence, endocrine therapy with a progestin-based regimen is appropriate. Chemotherapy will be used in most other cases, and the standard first-line regimen is carboplatin and paclitaxel. Few chemotherapy agents have been shown to produce meaningful response rates in the second-line setting. Molecularly targeted therapies such as mTOR inhibitors and antiangiogenic agents including bevacizumab have been studied but their role in the armamentarium remains uncertain.

IMPLICATIONS FOR PRACTICE

Following surgical resection and staging for endometrial cancer, adjuvant chemotherapy with carboplatin and paclitaxel can be administered to patients with a high risk for recurrence. This includes patients with stage IIIC disease with positive lymph nodes, and high-risk subsets of stage I disease such as serous carcinomas. In the metastatic setting, endocrine therapy can be considered, particularly for patients with lower-grade disease and a prolonged time to recurrence. Combined therapy with carboplatin and paclitaxel is the standard of care used for front-line chemotherapy. Antiangiogenic agents are clearly active, but how they should be integrated into treatment is not yet determined. Immunotherapy is a promising direction for patients with mismatch repair-deficient or polymerase ε-mutated tumors.

GnRH-(1-5) transactivates EGFR in Ishikawa human endometrial cells via an orphan G protein-coupled receptor

The decapeptide GnRH is known for its central role in the regulation of the hypothalamo-pituitary-gonadal axis. In addition, it is also known to have local effects within peripheral tissues. The zinc metalloendopeptidase, EC 3.4.24.15 (EP24.15), can cleave GnRH at the Tyr(5)-Gly(6) bond to form the pentapeptide, GnRH-(1-5). The central and peripheral effect of GnRH-(1-5) is different from its parent peptide, GnRH. In the current study, we examined the effect of GnRH-(1-5) on epidermal growth factor receptor (EGFR) phosphorylation and cellular migration. Using the Ishikawa cell line as a model of endometrial cancer, we demonstrate that GnRH-(1-5) stimulates epidermal growth factor release, increases the phosphorylation of EGFR (P < .05) at three tyrosine sites (992, 1045, 1068), and promotes cellular migration. In addition, we also demonstrate that these actions of GnRH-(1-5) are mediated by the orphan G protein-coupled receptor 101 (GPR101). Down-regulation of GPR101 expression blocked the GnRH-(1-5)-mediated release of epidermal growth factor and the subsequent phosphorylation of EGFR and cellular migration. These results suggest that GPR101 is a critical requirement for GnRH-(1-5) transactivation of EGFR in Ishikawa cells.

Hormonal therapy in advanced or recurrent endometrial cancer

BACKGROUND

Endometrial cancer is a cancer of the lining of the womb and worldwide is the seventh most common cancer in women. Treatment with hormones is thought to be beneficial in patients with endometrial cancer.

OBJECTIVES

To assess the indications, effectiveness and safety of hormone therapy for advanced or recurrent epithelial endometrial cancer.

SEARCH STRATEGY

We searched the Cochrane Gynaecological Cancer Group Trials Register, MEDLINE, EMBASE up to May 2009 and and CENTRAL (Issue 2, 2009). We also searched registers of clinical trials, abstracts of scientific meetings, reference lists of included studies, and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that studied hormonal therapy in adult women diagnosed with advanced or recurrent endometrial cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data and assessed risk of bias. Comparisons were restricted to single-trial analyses so we did not synthesise data in meta-analyses.

MAIN RESULTS

We found six trials (542 participants) that met our inclusion criteria. These trials assessed the effectiveness of hormonal therapy in women with advanced or recurrent endometrial cancer as a single agent, as part of combination therapy and as low versus high dose. All comparisons were restricted to single-trial analyses, where we found no evidence that hormonal therapy as a single agent or as a combination treatment prolonged overall or five-year disease-free survival of women with advanced or recurrent endometrial cancer. However, low-dose hormonal therapy may have had a benefit in terms of overall and progression-free survival (PFS) compared to high-dose hormonal therapy (HR 1.31, 95% CI 1.04 to 1.66 and HR 1.35, 95% CI 1.07 to 1.71 for overall and PFS, respectively).

AUTHORS' CONCLUSIONS

We found insufficient evidence that hormonal treatment in any form, dose or as part of combination therapy improves the survival of patients with advanced or recurrent endometrial cancer. However, a large number of patients would be needed to demonstrate an effect on survival and none of the included RCTs had a sufficient number of patients to demonstrate a significant difference. In the absence of a proven survival advantage and the heterogeneity of patient populations, the decision to use any type of hormonal therapy should be individualised and with the intent to palliate the disease. It is debatable whether outcomes such as quality of life, treatment response or palliative measures such as relieving symptoms should take preference over overall and PFS as the major objectives of future trials.

Effect of GnRH analogues and octreotide treatment on apoptosis and the cell proliferation of endometrium adenocarcinoma cell lines

OBJECTIVE

The aim of this study was to compare apoptotic and antiproliferative effects of gonadotropin-releasing hormone analogues and their combination with octeotide on endometrioid endometrial cancer cell lines.

MATERIAL AND METHOD

Women diagnosed with endometrioid adenocarcinoma at the department of Gynecology and Obstetric of Kocaeli University Medical School were included in this research. Endometrium cancer cell lines obtained from three patients were used for this study. After trypsinization in 0.5% in calcium magnesium, free phosphate buffer solution (CMFPBS) cells were seeded on glass slides in 24-well plates containing DMEM-F12 medium and 10% fetal calf serum as culture medium. Cells were incubated for 24 hours at 37ºC in 5% CO2. GnRH agonist leuprolide (Lucrin 1 μmol/L), GnRH antagonist ganirelix (Orgalutran 1 μmol/L), leuprolide with octreotide (Sandostatin 10-6 mol/L), ganirelix with octreotide and no drug were added to the wells. Apoptosis and cells proliferations were evaluated after 12, 24, 48 and 72(th) hours of incubation. The percentage of apoptotic cells was evaluated by TdT mediated biotin-dUTP nick-end labeling (TUNEL) method; cell proliferation was assessed by bromodeoxyuridine (BrdU) incorporation.

RESULTS

Apoptotic index in grade I EEC cell line among ganirelixoctreotide treated cells and leuprolide-octreotide combination therapy were respectively higher than the untreated control (p<0.001, p=0.001). The number of apoptotic cells in grade II EEC cell line among leuprolide-octreotide and leuprolide were significantly (p<0.001, p<0.001) higher than in controls. In grade III EEC cell line, the number of TUNEL positive cells among leuprolide, ganirelix and ganirelixoctreotide therapiy groups were significantly higher than in untreated control. Time dependent antiproliferative effect was obtained with leuprolide and leuprolide-octreotide in grade I EEC (p<0.001, p<0.001). Grade II EEC cell line is not influenced by hormonotherapies. However, the antiproliferative effect was obtained with ganirelix, leuprolide and leuprolide-octreotide in grade III cell line.

CONCLUSION

GnRH analogues appears to have a direct effect, enhancing the apoptotic index and decreasing the cell proliferation in endometrial adenocancer cell lines.

Management of Recurrent Endometrioid Endometrial Carcinoma: An Overview

In this paper, an overview of the literature on the management of recurrent endometrial cancer is presented, focusing on patients with histopathologic endometrioid type of tumors. The different treatment modalities are described, and a management recommendation scheme is presented. Indications for surgical treatment depend on resectability, site and size of the tumor, and performance status of the patient. Indications for radiotherapy depend on the site of the recurrence and also on the initial therapy received. When considering systemic treatment for patients with recurrent endometrial cancer, it is important to take into account the general health status and condition of the patient as well as which prior therapy the patient has received. The treatments of choice for patients with hormone-sensitive tumors (positive receptor levels, low-grade tumors, and long disease-free interval) are progestagens as first-line treatment and tamoxifen as second-line treatment. Patients with high-grade tumors, negative hormone receptor levels, and short treatment-free interval are best treated with chemotherapy. Paclitaxel, doxorubicin, and cisplatin are the most active combination therapy for these patients but with significant toxicity. In phase II studies, the combination therapy with paclitaxel and carboplatin seems to be as effective but less toxic and can be administered in outpatient clinic. The literature on the management of patients with recurrent endometrial cancer is discussed in detail. The different sites of recurrent disease (ie, local, regional, and/or distant) are evaluated separately; management recommendations are proposed, and alternative approaches are given.

Hormonal therapies and gynaecological cancers

Hormonal therapy has an established place in the management of women with gynaecological malignancies, including first-line therapy for recurrent receptor-positive endometrial cancer and low-grade stromal sarcoma. There is no place for adjuvant hormonal treatment of these cancers after primary surgery. Primary treatment with either oral or intra-uterine progestagens to preserve fertility in younger women with endometrial carcinoma is effective in about 70% of cases. Response rates to tamoxifen in advanced/recurrent ovarian cancers approximates 10%. To the authors' knowledge, no studies that reasonably compare different progestagens, different routes of therapy, different doses and different hormonal preparations have been published.

Fertility-Preserving Treatment in Young Women with Endometrial Cancer

Nonsurgical fertility-preserving treatment of well-differentiated endometrial cancer with systemic progestins has been described for young women who desire to preserve their fertility. The overall response to progestin treatment in 9 retrospective studies is 79% with 79 subsequent live births. Recurrence can be expected in approximately 36-40% of conservatively treated patients who initially responded. Synchronous ovarian cancer has been reported in approximately 9%. However, amongst 162 receiving systemic, continuous treatment with progestins no death caused by cancer has been reported. We review guidelines for diagnosis, treatment and follow-up in young women undergoing conservative treatment for endometrial cancer.

Effective treatment of experimental human endometrial cancers with targeted cytotoxic luteinizing hormone–releasing hormone analogues AN-152 and AN-207

OBJECTIVE

To treat experimental human endometrial cancers based on targeted chemotherapy with the cytotoxic luteinizing hormone-releasing hormone (LHRH) analogues AN-152 and AN-207.

DESIGN

Experimental study using athymic nude mice bearing xenografts of HEC-1A and RL-95-2 human endometrial cancers to assess the efficacy and toxicity of AN-152 and AN-207. The expression of LHRH receptors in HEC-1A and RL-95-2 cancers was determined by reverse transcription-polymerase chain reaction, Western blot analysis, and radioligand binding assays.

SETTING

Experimental laboratory research.

ANIMAL(S)

Female athymic nude mice (Ncr, nu/nu).

INTERVENTION(S)

Animals were treated with IV injections of the cytotoxic LHRH analogues AN-152 and AN-207 and their respective cytotoxic radicals doxorubicin (DOX) and AN-201 (2-pyrrolinodoxorubicin) on a control vehicle solution.

MAIN OUTCOME MEASURE(S)

Tumor volume, final tumor weight, tumor doubling time, body weight, white blood cell count, and LHRH receptor expression.

RESULT(S)

AN-152 significantly inhibited the growth of HEC-1A tumors. AN-207 also significantly suppressed the proliferation in vivo of HEC-1A and RL-95-2 cancers. The cytotoxic radicals DOX and AN-201 had no effect. Furthermore, mRNA for LHRH receptors, LHRH receptor protein, and high-affinity binding sites for LHRH were demonstrated on tumors.

CONCLUSION(S)

Targeted chemotherapy with AN-152 and AN-207 strongly inhibits the growth of human endometrial cancers, which express LHRH receptors, and could provide a new treatment modality for women with advanced endometrial carcinoma.

Detection of gonadotropin-releasing hormone receptor and its mRNA in primary human epithelial ovarian cancers

The hypothalamic neuropeptide gonadotropin-releasing hormone (GnRH) serves a key role in regulating mammalian reproductive function. An extrapituitary role for GnRH in the normal and malignant reproductive tissues has been postulated. The purpose of our study is to demonstrate the presence and levels of GnRH receptor (RGnRH) protein and its mRNA in normal and malignant tissues of ovary. Normal human ovarian tissues (n = 13), as well as epithelial ovarian cancer specimens from stages I-IV (n = 39), were obtained from appropriate patients at operation room. Monoclonal antibodies against RGnRH were used for immunohistochemical evaluation of paraffin-embedded ovarian tissue sections by methods of streptavidin-biotin immunostaining. The molecular size and levels of RGnRH were determined by enhanced chemiluminescence-Western blot assay. The amount of RGnRH mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The rate of positive immunostaining in ovarian cancers was 53.8% (21/39). The rate of positive staining in the late stage (stages III and IV) was significantly higher than that in the early stage (stages I and II). A single band of molecular weight of about 60 kDa was detected from protein extracts of ovarian cancer as well as from normal ovary. The mean values of fold increase of signal intensities of 60 kDa detected by Western blots in stages I-IV ovarian cancers were 2.39, 2.42, 2.78, and 3.62, respectively, as compared with normal ovarian tissues. The overall positive rate of Western blot analysis for ovarian cancers was 59% (23/39). The mean values of signal intensity of RT-PCR products of RGnRH mRNA in stages I-IV were 2.24, 2.58, 3.10, and 3.20, respectively. The positive rate of overexpression of RGnRH mRNA in ovarian cancer was 70% (21/30). The differences of mean values of signal intensities of Western blot staining (2.41 versus 2.85) as well as RT-PCR products (2.40 versus 3.11) between the early stage and the late stage of ovarian cancers were statistically nonsignificant. Mechanism of autocrine regulation of tumor growth in human epithelial ovarian cancer can be explained by the coexistence of GnRH, RGnRH, and its mRNA, according to our own and other studies. The level of RGnRH expressed by ovarian cancer might be used for targeting chemotherapeutic agents to those patients who harbor RGnRH-positive tumors.

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.

Fertility-preserving treatment in young patients with endometrial adenocarcinoma

BACKGROUND

Hormone therapy alone for early-stage, low-grade endometrial carcinoma arising in young women has been reported occasionally in case reports or small series. However, a comprehensive guideline for selection, treatment, and follow-up is not available as yet.

METHODS

In the current study, the authors' evaluated the outcome of a cohort of young women with clinically diagnosed endometrial adenocarcinoma Stage IA, Grade 1 who were selected for fertility-preserving treatment by stringent staging procedures and treated in a standard protocol using combinations of megestrol acetate, tamoxifen, and gonadotropin-releasing hormone analog (GnRHa).

RESULTS

Nine eligible patients were treated between 1991 and 1999. The median age of the patients was 32 years (range, 30-39 years). Of the 9 patients, 8 (88.9%) achieved complete remission after hormone therapy. Four patients had ever conceived (two patients had three term pregnancies and underwent consolidation hysterectomy after completion of family planning). Only one patient underwent hysterectomy for failure to respond, whose tumor was estrogen receptor (ER)/progesterone receptor (PgR) positive by immunostaining but negative by ligand-binding method. Another patient, whose tumor was ER negative/PgR positive, had residual carcinoma on the first assessment and achieved complete remission after replacement of tamoxifen with a GnRHa. Four responders later developed recurrent endometrial carcinoma. One underwent immediate hysterectomy. Two were successfully re-treated with hormone therapy, but the other did not respond and underwent hysterectomy. All nine patients have been alive without evidence of disease 25-113 (median, 69) months from initial diagnosis.

CONCLUSIONS

The treatment strategy described in the current study is feasible. A larger multicenter trial of fertility-preserving treatment is warranted for nulliparous young patients with well selected Stage I, Grade 1, endometrial adenocarcinoma.

Hormonal treatment of endometrial carcinoma

Endometrial cancer has typically been regarded as a relatively benign disease. However, survival rates for patients with advanced-stage or recurrent disease are very poor and more adequate systemic treatment is certainly needed. Being a tumor that arises from a hormone responsive tissue, endometrial cancer is a logical target for endocrine manipulation. This article gives an overview of our current knowledge on hormonal therapy and highlights the large potential for improvement in results of such therapy. Target areas for future research are described.

Hypothalamic hormones and cancer

The use of peptide analogs for the therapy of various cancers is reviewed. Inhibition of the pituitary-gonadal axis forms the basis for oncological applications of luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists, but direct effects on tumors may also play a role. Analogs of somatostatin are likewise used for treatment of various tumors. Radiolabeled somatostatin analogs have been successfully applied for the localization of tumors expressing somatostatin receptors. Studies on the role of tumoral LH-RH, growth hormone-releasing hormone (GH-RH), and bombesin/GRP and their receptors in the proliferation of various tumors are summarized, but the complete elucidation of all the mechanisms involved will require much additional work. Human tumors producing hypothalamic hormones are also discussed. Treatment of many cancers remains a major challenge, but new therapeutic modalities are being developed based on antagonists of GH-RH and bombesin, which inhibit growth factors or their receptors. Other approaches consist of the use of cytotoxic analogs of LH-RH, bombesin, and somatostatin, which can be targeted to receptors for these peptides in various cancers and their metastases. These new classes of peptide analogs should lead to a more effective treatment for various cancers.

Longstanding survival without cancer progression in a patient affected by endometrial carcinoma treated primarily with leuprolide

We report here a case of a patient affected by endometrial cancer and treated primarily with leuprolide, the surgical approach being unfeasible due to her compromised conditions. The therapy was continued for more than 6 years, and no progression of the disease was observed. During this period, some histological and immunohistochemical evaluations of the tumour (morphology, grading, proliferation and apoptotic index, E-cadherin expression) were performed. Furthermore, the expression of m-RNA for luteinizing-hormone releasing hormone (LHRH) receptors was determined. The results showed a discrepancy between some biological parameters of the tumour and its clinical characteristics. In fact, despite features suggestive of a progression of the cancer (such as the increase of both tumour grading and proliferating capacity (MIB-1), and a fall in the reparative process (appearance of mutated p53, reduced expression of both bcl-2 and c-erb-2) being detected, neither local invasion nor metastatic lesions were clinically observed. This discrepancy might be due to the maintenance of high levels of E-cadhezin. Moreover, since this tumour was shown to express mRNA for LHRH receptors, new evidence is provided about the favourable impact of LHRH analogue treatment in patients affected by endometrial cancer.

Hormonal treatment of endometrial cancer: past, present and future

The concept that hormonal therapy may be useful in the treatment of endometrial cancer antedated the pharmaceutical availability of progestational compounds. By 1959, initial studies demonstrated the ability of progestins to reverse endometrial hyperplasias. Thereafter, progestins and other hormonal agents have been used in various roles as treatment for endometrial cancers. This chapter reviews the use of hormonal agents for the treatment of primary and metastatic/recurrent endometrial cancer, as well as such treatment in an adjuvant setting. Major problems in enhancing the efficacy of endocrine therapy of cancers arising from hormonally responsive tissues are also considered. The regulations of steroid-hormone receptor expression in endometrial and breast cancers continues to be an active area of research interest.

Ovarian surface epithelium: biology, endocrinology, and pathology

The epithelial ovarian carcinomas, which make up more than 85% of human ovarian cancer, arise in the ovarian surface epithelium (OSE). The etiology and early events in the progression of these carcinomas are among the least understood of all major human malignancies because there are no appropriate animal models, and because methods to culture OSE have become available only recently. The objective of this article is to review the cellular and molecular mechanisms that underlie the control of normal and neoplastic OSE cell growth, differentiation, and expression of indicators of neoplastic progression. We begin with a brief discussion of the development of OSE, from embryonic to the adult. The pathological and genetic changes of OSE during neoplastic progression are next summarized. The histological characteristics of OSE cells in culture are also described. Finally, the potential involvement of hormones, growth factors, and cytokines is discussed in terms of their contribution to our understanding of the physiology of normal OSE and ovarian cancer development.

Gene expression of gonadotropin-releasing hormone and its receptor in rat pancreatic cancer cell lines

The regression of experimental and clinical pancreatic cancers by treatment with gonadotropin-releasing hormone (GnRH) agonists or antagonists has been repeatedly reported and is usually presumed to result from the creation of a sex steroid deficiency. There are, however, indications that GnRH analogs can also suppress the growth of the tumor cells in vitro and that specific binding sites for GnRH are present on membranes of these cells. The regulatory role of GnRH in rat pancreatic adenocarcinoma was investigated by examining the gene for GnRH and GnRH receptor (GnRH-R) in two pancreatic tumor cell lines (AR42J and ARIP). Reverse transcriptase polymerase chain reaction and Southern blot analysis indicated both GnRH-mRNA and GnRH-R-mRNA transcripts in the two cell lines. This is the first report raising the possibility of an autocrine/paracrine role for GnRH in rodent malignant pancreas.

Regulation of endometrial cancer cell growth by luteinizing hormone (LH) and follicle stimulating hormone (FSH)

Gonadotrophin releasing hormone analogues (GnRHa) have been used to treat recurrent endometrial cancer. However, the mode of action is uncertain. Our previous studies showed no direct effect of GnRHa on endometrial cancer cell growth in vitro. We have now examined the effect of luteinizing hormone (LH) and follicle stimulating hormone (FSH) on endometrial cancer cell growth. The aim was to determine whether suppression of pituitary LH and FSH by GnRHa could explain the tumour regression seen in up to 44% of patients treated with this drug. We show that recombinant human LH and FSH (rhLH and rhFSH) produce a concentration dependent stimulation of the endometrial cancer cell line HEC-1A, in serum-free medium (maximum increase of 62 and 50% respectively relative to untreated controls). This increase is equivalent to that obtained by addition of 10% newborn calf serum. Growth of the Ishikawa cell line in culture increases in the presence of rhLH (maximum increase of 67%) but not with rhFSH. Using RT-PCR, we show that the Ishikawa cell line intermittently expresses receptor mRNA of LH but not of FSH; there is no expression of either mRNA by HEC-1A. Classically, both LH and FSH act via cAMP linked membrane receptors. However, neither rhLH nor rhFSH elicit cAMP production in either of our endometrial cancer cell lines. Thus, although a growth response to LH and FSH can be shown, and some cells express the LH receptor, stimulation appears to be via a pathway separate from that of the classical gonadotrophin receptor.

Novel strategies for systemic treatment of endometrial cancer

The median survival of women with advanced or recurrent endometrial cancer is less than one year. Of the women with early stage endometrial cancer and poor prognostic factors like high grade or deep myometrial invasion, 40% will recur. Over the last decade, incredible strides have been taken in evaluating systemic therapy for this disease, however, survival rates remain poor. Progestin therapy offers a 10 - 20% response rate and survival of less than one year. Progestins are most effective in women with well-differentiated tumours and long disease-free interval. There is no role for adjuvant progestin therapy in early stage disease. Single-agent chemotherapy with most activity include ifosfamide, cisplatin/carboplatin, doxorubicin and paclitaxel. Combination chemotherapy provides a response rate of 40 - 60%, however, median survival is still less than a year. New areas of research include the identification and evaluation of new active endocrine therapies (i.e., LY-353381.HCl and letrozole), chemotherapeutics (i.e., paclitaxel), evaluating chemotherapeutic agents in combination (i.e., paclitaxel, doxorubicin and platinum), in addition to radiation or instead of radiation. New avenues under development involve the specific molecules and pathways responsible for the initiation and growth of endometrial carcinoma (i.e., Herceptintrade mark). Exciting developments in the understanding of the molecules involved in tumour development and metastasis will allow the development of specific and selective inhibitors.

GnRH receptor and apoptotic signaling

In addition to its hypophysiotropic action, gonadotropin-releasing hormone (GnRH) can modify activity in extrapituitary organs and peripheral tumors. GnRH analogs are the preferred treatment for advanced and even metastatic or recurring carcinomas in vivo and in vitro. Hormone-responsive tumors undergo apoptosis with the appropriate stimulus; GnRH-induced tumor growth arrest may result from stimulated apoptotic cell death. The sensitivity of tumors and normal tissue to GnRH is strongly associated with the possession of receptors for GnRH as well as other hormonal control. Despite the lack of a precise apoptotic signaling cascade through GnRH receptors, biochemical events observed within a plasma membrane appear to constitute the most convincing evidence that the membrane event is primarily stimulated during cell activation by GnRH. GnRH receptors in tumors differ from those in pituitary gonadotrophs in some aspects, in particular with regard to the transmembrane signaling cascade. The intramembranous phenomena that occur independently of the contribution of other organelles upon tumoral GnRH receptor engagement include (i) activation of phosphotyrosine phosphatase and loss of phosphotyrosine from the endogenous membrane protein and (ii) phosphoinositide and perhaps sphingomyelin cleavage producing lipid-originated second messengers. GnRH has also been demonstrated to increase Fas ligand expression within plasma membrane, which is known to promote apoptotic cell death through attack on Fas-positive cells within tumors. The Fas-Fas ligand complex might, at least in part, account for the antiproliferative action of the hormone. An understanding of the relationship between the extracellular (hormonal) stimuli that leads to cell death and the intracellular events regulating growth arrest on GnRH action may fundamentally help clarify the therapeutic approach to all hormone-dependent carcinomas that respond to stimuli that lead to apoptosis. In this chapter, we review the recent literature and the results of our studies on GnRH-induced membrane events and summarize what is currently known about this promising antiproliferative function.

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.

Cell cycle arrest in endometrial carcinoma cells exposed to gonadotropin-releasing hormone analog

Gonadotropin-releasing hormone (GnRH) has been shown to have an inhibitory effect on the growth of several hormone-dependent human tumors. We have treated a human endometrial cancer cell line which expresses GnRH receptor with GnRH analog, D-Trp6-LHRH, in order to study whether there are differences in cell cycle kinetic response. Flow cytometric analysis revealed that cultured carcinoma cells showed a cell cycle arrest at the G1-S transition after treatment with 10 microM D-Trp6-LHRH for 36 h. Western blot analysis showed that the level of p16 protein was obvious following 24 h of D-Trp6-LHRH treatment. These results suggest that the mechanism by which GnRH inhibits the growth of endometrial carcinoma cells may include effects on cell cycle arrest.

Regression of endometrial hyperplasia after treatment with the gonadotrophin-releasing hormone analogue triptorelin: a prospective study

Endometrial hyperplasia is thought to be caused by the prolonged, unopposed oestrogenic stimulation of the endometrium. The regression of hyperplastic back to normal endometrium is the main purpose of any conservative treatment in order to prevent development of adenocarcinoma. The aim of this study was to evaluate the regression of hyperplastic to normal endometrium in patients with various forms of endometrial hyperplasia after treatment with the gonadotrophin-releasing hormone analogue (GnRHa) triptorelin for 6 months. Fifty-six patients with endometrial hyperplasia were enrolled in this trial; 39 patients (group I) presented simple hyperplasia, 14 (group II) complex hyperplasia and three (group III) atypical complex hyperplasia. All patients were treated with triptorelin for 6 months. Bleeding control during treatment was excellent. A post-treatment curettage for estimation of endometrial histology was performed on 54 out of 56 patients 100.1 +/- 44.7 days after the last triptorelin dose, following the restoration of pituitary function. Regression of hyperplastic to normal endometrium was observed in 32 (86.5%) out of 37 patients in group I and in 12 (85.7%) out of 14 in group II. Persistence of simple hyperplasia was found in five (14.5%) out of 37 patients in group I. Persistence of complex hyperplasia was found in 1 (7.1%) out of 14 patients and progression to atypical complex hyperplasia in another one (7.1%) woman in group II. In some of these cases, the presence of risk factors such as obesity, diabetes mellitus and ovulatory disturbances may contribute to the disease persistence despite therapy. On the other hand, in group III, none of the three patients had normal post-treatment endometrial histology. It seems, therefore, that in cases of endometrial hyperplasia without atypia, the administration of the GnRHa triptorelin is associated with high regression rates to normal endometrium. Conversely, the presence of atypia seems to be a poor prognostic factor. Treatment tolerance and bleeding control during therapy is excellent.

Luteinizing hormone-releasing hormone analogs: their impact on the control of tumorigenesis

The development of the luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists and the principles of their clinical use were reviewed. In the 28 years that have elapsed since the elucidation of the structure of LH-RH, various applications in gynecology, reproductive medicine, and oncology have been established for LH-RH agonists and antagonists. These clinical applications are based on inhibition of the pituitary and the gonads. The advantage of the LH-RH antagonists is due to the fact that they inhibit the secretion of gonadotropins and sex steroids immediately after the first injection and thus achieve rapid therapeutic effects in contrast to the agonists, which require repeated administration. LH-RH antagonists should find applications in the treatment of benign gynecologic disorders and benign prostatic hypertrophy and in assisted reproduction programs. The primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists, but antagonists like Cetrorelix already have been tried successfully. Antagonists of LH-RH might be more efficacious than agonists in treatment of patients with breast cancer as well as ovarian and endometrial cancer. Recently, practical cytotoxic analogs of LH-RH that can be targeted to LH-RH receptors on tumors have been synthesized and successfully tested in experimental cancer models. Targeted cytotoxic LH-RH analogs show a great promise for therapy of prostate, breast, and ovarian cancers.

Rational use of agonists and antagonists of luteinizing hormone-releasing hormone (LH-RH) in the treatment of hormone-sensitive neoplasms and gynaecologic conditions

Analogues of luteinizing hormone-releasing hormone (LH-RH) have made possible new approaches to the treatment of some hormone-dependent cancers and diseases and conditions which result from inappropriate sex hormone levels. In the fields of both gynaecology and oncology, the development of sustained delivery depot systems has played a key role in the clinical use of LH-RH agonists and will be also essential for the LH-RH antagonists. Clinical results show that therapy with agonists of LH-RH is the preferred method of treatment for men with advanced prostate cancer. For prostate cancer and other indications, the new LH-RH antagonists such as Cetrorelix may offer an advantage based on the fact that they inhibit LH, FSH and sex-steroid secretion from the start of the administration and thus reduce the time of the onset of therapeutic effects. The use of antagonists would avoid the temporary clinical "flare-up" of the disease which can occur with the agonists in men with prostate cancer. The rapid shrinkage of the prostate and improvement in urinary symptoms obtained with Cetrorelix in men with benign prostatic hyperplasia (BHP) suggests that LH-RH antagonists offer a therapeutic alternative in patients who are considered poor surgical risks. Various experimental and clinical studies suggest that analogues of LH-RH might be useful for treatment of premenopausal women with oestrogen-dependent breast cancer. LH-RH antagonists such as Cetrorelix could be also considered for hormonal therapy of epithelial ovarian cancer which responds only marginally to the agonists, and for treatment of endometrial cancer. Many investigators have reported beneficial effects of LH-RH agonists in the treatment of patients with leiomyomas. LH-RH antagonists also appear to be promising for therapy of uterine leiomyomas, and in addition might be useful for treatment of endometriosis and polycystic ovarian disease (PCOD). LH-RH agonists have been employed in in vitro fertilization and embryo transfer (IVF-ET) programs to prevent a premature rise in LH and various results suggest that the use of antagonist Cetrorelix in assisted reproduction procedures, could be even more advantageous. For most of these indications, the use of sustained release depot preparations will be required.

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.

Adenocarcinoma cells are targeted by the new GnRH-PE66 chimeric toxin through specific gonadotropin-releasing hormone binding sites

Luteinizing hormone-releasing hormone, also termed gonadotropin-releasing hormone (GnRH), accounts for the hypothalamic-pituitary gonadal control of human reproduction. The involvement of GnRH has been demonstrated in several carcinomas of hormone-responsive tissues. Exploiting this common feature, we constructed a Pseudomonas exotoxin (PE)-based chimeric toxin (GnRH-PE66) aimed at targeting those cancer cells bearing GnRH binding sites. We report here the strong growth inhibition and killing of a surprisingly wide variety of cancers, confined to the adenocarcinoma type. These cancer cells arising from hormone-responsive tissues, as well as non-responsive ones, express specific GnRH binding sites as indicated by the marked killing of ovarian, breast, endometrial, cervical, colon, lung, hepatic, and renal adenocarcinoma. This cytotoxicity is specific as it could be blocked upon addition of excess GnRH. The specificity of GnRH-PE66 chimeric toxin was also confirmed by GnRH binding assays, and its ability to prevent the formation of colon cancer xenografts in nude mice is presented. Although the functional role of specific GnRH binding sites in human carcinomas remains obscure, GnRH-PE66 displays considerable targeting potential and its use as a therapeutic agent for cancer should be considered.

Treatment of endometrial hyperplasias with gonadotropin-releasing hormone agonists: pathological, clinical, morphometric, and DNA-cytometric data

On the basis of the recently reported observation that gonadotropin-releasing hormone agonists (GnRH-a) can affect endometrial cell proliferation, both indirectly, through the hormonal axis, and directly, by acting on the GnRH-a receptors, we investigated how far GnRH-a can be used as a new treatment mode for endometrial hyperplasias. Forty-two women, aged 28-60 years, with histologically confirmed simple (n = 30) or complex (n = 12, 2 with atypias) hyperplasia of the endometrium were involved in the study. According to the protocol they were treated for 6 months with GnRH-a (leuprolide acetate or triptorelin), and each patient underwent uterine curettage in the third and the sixth month of treatment, and 6 and at least 12 months after cessation of the treatment, for histological examination and morphometric and DNA-cytometric evaluation of the endometrium (mean pathological follow-up, 19.2 months; mean clinical follow-up, 30.7 months). During treatment, most of the women first revealed endometrial atrophy, and, after cessation of the treatment, again an atrophic or mainly functional endometrium; in 7 women, all with initial diagnosis of simple hyperplasia, the endometrial hyperplasia reappeared, which led in all 7 cases to hysterectomy. The mean values of almost all morphometric and DNA-cytometric parameters during and after treatment showed statistically significant changes in relation to pretreatment values, indicating a decrease in the proliferative activity of the endometrial cells; the GnRH-a antiproliferative effect was still active for a long time after cessation of the therapy. Our results, based for the first time not only on histological but also on serial nuclear morphometric and DNA-cytometric examinations of the endometrial cells and on the longest follow-up time, support the view that in cases of endometrial hyperplasia, especially of complex type, the use of GnRH agonists, which decrease the proliferative tendency of endometrial cells, could represent an alternative conservative therapeutic approach, which, however, requires close monitoring of the endometrium.

Gi protein activation of gonadotropin-releasing hormone-mediated protein dephosphorylation in human endometrial carcinoma

OBJECTIVE

Gonadotropin-releasing hormone receptor is demonstrated in uterine endometrial carcinomas. This study was performed to determine gonadotropin-releasing hormone receptor-mediated membrane events and to identify the guanosine triphosphate binding protein (G protein) subtypes linked to gonadotropin-releasing hormone receptor in the tumors.

STUDY DESIGN

Endometrial carcinomas surgically removed had been screened for gonadotropin-releasing hormone receptor expression before plasma membrane isolation. The phosphoprotein level was observed in the phosphorus 32-labeled incorporation from [gamma-32P]adenosine triphosphate into the isolated plasma membranes. The Gi (alpha subunit) protein was detected by immunoblotting and pertussis toxin-catalyzed adenosine diphosphate ribosylation.

RESULTS

Incubation of phosphorus 32-labeled membranes with a gonadotropin-releasing hormone analog in the presence of guanosine thiotriphosphate caused a remarkable loss of phosphoprotein from 35 kd protein. This dephosphorylation action was dose dependent of the gonadotropin-releasing hormone analog, and the maximal effect (90% loss) occurred at 100 nmol/L. Pertussis toxin brought about adenosine diphosphate ribosylation of an immunodetected G alpha i. Gonadotropin-releasing hormone analog alone or guanosine thiotriphosphate alone had no effect. Pretreatment of the membrane with the pertussis toxin completely inhibited gonadotropin-releasing hormone-mediated dephosphorylation of the 35 kd protein.

CONCLUSION

These data demonstrate the coupling of gonadotropin-releasing hormone receptor to protein dephosphorylation through Gi, raising the possibility that the antimitogenic action of gonadotropin-releasing hormone may occur by release of the action of protein phosphorylation to promote cell growth.

LHRH agonist treatment of breast cancer and gynecological malignancies: a review

Since 1982 LHRH agonists have been used as a treatment modality in patients with disseminated breast cancer and gynecologic malignancies, based on the assumption of steroid dependence of these cancers. They have been successfully used in the treatment of premenopausal women with breast cancer; response rates reported are 31-63%. Less optimistic results have been reported in postmenopausal breast cancer patients as well as in the treatment of women suffering from ovarian cancer. Response rates for treatment of postmenopausal breast- and ovarian cancer patients appear to be up to 22% and 29%, respectively. Studies using LHRH agonists to treat endometrial and cervical intra-epithelial neoplasia are still rare and, until now, no data about the efficacy of LHRH agonists in treating these malignancies have been reported. This paper reviews clinically important studies of LHRH agonists, including a rationale for the use of LHRH agonists in breast cancer and gynecological cancer treatment. In view of the changed endocrine state in postmenopausal women on the one hand and alterations in endocrine metabolism in breast cancer tissue on the other hand, it is concluded that it might be more effective to use a combination of LHRH agonists and other endocrine modalities to treat disseminated breast cancer and gynecological malignancies.

Leuprorelin. A review of its pharmacology and therapeutic use in prostatic cancer, endometriosis and other sex hormone-related disorders

Leuprorelin (leuprolide acetate) is a gonadotrophin-releasing hormone (GnRH) analogue used to treat a wide range of sex hormone-related disorders including advanced prostatic cancer, endometriosis and precocious puberty. It acts primarily on the anterior pituitary, inducing a transient early rise in gonadotrophin release. With continued use, leuprorelin causes pituitary desensitisation and/or down-regulation, leading to suppressed circulating levels of gonadotrophins and sex hormones. Clinical trials in men with advanced prostatic cancer demonstrate that leuprorelin (usually monthly depot injections of 3.75 or 7.5 mg) is less likely to cause serious adverse cardiovascular effects than diethylstilbestrol, and has comparable efficacy to bilateral orchiectomy or other GnRH analogues. Therefore, the choice between leuprorelin and orchiectomy may be made on the basis of the patient's treatment preference, along with specific patient characteristics and cost implications. Monthly intramuscular or subcutaneous administration of depot leuprorelin 3.75 mg was superior to placebo, and comparable to oral danazol 800 mg/day or intranasal buserelin 900 micrograms/day, in achieving objective and subjective responses in women with endometriosis. Thus, leuprorelin is an effective alternative to other treatments for women with endometriosis, but the recommended duration of its use in this clinical setting is limited to 6 months because it reduces bone mineral density. In children with central precocious puberty, leuprorelin (usually monthly intramuscular or subcutaneous injections of depot leuprorelin 3.75 to 15mg) decreases mean growth velocity and signs of sexual maturation and increases predicted adult height compared with baseline measurements. Although effects on final adult height are predicted from available data and require confirmation in long term follow-up studies, the absence of effective alternatives to GnRH analogues makes leuprorelin a first-line therapy for children with this rare disease. In women with uterine leiomyomata, monthly intramuscular administration of depot leuprorelin 3.75 mg for 6 months markedly reduces uterine volume and fibroid-related symptoms, but, as with other GnRH analogues, these effects dissipate following discontinuation of the drug. As adjuvant therapy in women undergoing in vitro fertilisation or gamete intrafallopian transfer, leuprorelin (usually 0.5 to 1 mg/day subcutaneously) reduces the risk of cancelled cycles for oocyte retrieval by preventing premature luteinisation. While some studies demonstrate an improvement in intermediate end-points such as increased number of mature oocytes retrieved and embryos available for transfer, a significant effect has not been demonstrated on the rate of live births per stimulated cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Clinical response of abnormal endometrial growth to hormonal treatment

The diverse types of abnormal endometrial tissue growth have received different forms of treatment, with a particular emphasis on the use of hormonal agents. Hyperplastic endometria have benefited from progesterone or progestin therapies, with good results. Endometrial cancer is a disease with a major indication for surgical treatment. However, advanced clinical stages have been shown to improve as a result of different medical treatments. This presentation reviews the literature on this subject, includes some considerations on the role of some antiestrogens as endometrial tumor promoters in certain patients undergoing adjuvant therapy, and discusses the possibilities of Gn-RH analogs, one of the recent proposals in the treatment of adenocarcinomas and endometrial hyperplasia, including morphological observations of an investigation currently in progress in our department.

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.

Regulation of endometrial cancer cell growth by insulin-like growth factors and the luteinizing hormone-releasing hormone antagonist SB-75

The involvement of IGFs in growth regulation of the Ishikawa endometrial tumor cell line and the possible interference of LH-RH analogues with a potential autocrine or paracrine loop involving IGFs was evaluated. The mitogenic effects of IGF-I, IGF-II, and insulin were compared. IGF-I was found to be 3-fold more potent than IGF-II and 30-fold more potent than insulin, suggesting that the effects of these growth factors are mediated by the IGF-I receptor. Ishikawa endometrial cancer cells secrete IGF-II, but not IGF-I, and insulin (1 microM) stimulates IGF-II release. The LH-RH antagonist [Ac-D-Nal(2)1, D-Phe(4Cl)2, D-Pal(3)3, D-Cit6, D-Ala10]-GnRH (SB-75, CETRORELIX) inhibited basal and IGF-induced growth. Moreover, this antagonist almost completely inhibited IGF-II release from Ishikawa cells, while having no significant effect on the number or affinity of IGF-I binding sites. Inhibition of IGF-II release occurred at a lower SB-75 concentration than that needed for a reduction in cell number. The ED50 of SB-75 for IGF-II release was 0.3 microM as compared to 1.5 microns concentration which is required for reduction in cell number, suggesting that inhibition of growth factor release precedes cell growth inhibition. We conclude that the LH-RH antagonist SB-75 can inhibit the growth of endometrial cancer cells by interfering with the autocrine action of IGF-II and also by directly inhibiting the growth-stimulatory effects of IGFs, probably through effects on a post-receptor mechanism.

Systemic treatment in disseminated endometrial cancer

Both hormonal agents and chemotherapy are of value in the treatment of selected patients with endometrial cancer. In unselected patients with advanced disease about 25% respond to progestational agents and 40% to combination chemotherapy. The choice between the two treatments is made on the basis of a number of prognostic factors, such as receptor status, tumour grade, performance status and tumour burden. Further improvement of treatment outcome is to be expected from new agents such as gonadotrophin releasing hormone analogues, taxol and modulation of 5-fluorouracil.

GnRH analogs in gynecological oncology: a review

Chronic GnRH analogs (GnRH-A) administration has proven to be effective for the control of some hormone-dependent tumors. GnRH-A are now in the standard treatment of prostatic cancer. In the present paper experimental and clinical data on the use of GnRH-A in gynecologic oncology are reviewed in order to identify a possible role in the therapy of breast, endometrial and ovarian cancer. Besides the indirect hormonal effect of GnRH-A, mediated by the suppression of gonadal steroidogenesis, in vitro evidence suggests a direct anti-proliferative action involving autocrine-paracrine regulation of cellular function. In advanced or recurrent breast cancer objective responses were observed in 157 out of 378 premenopausal patients (41%) and in 18 out of 166 postmenopausal women (10%). In ovarian cancer complete and partial responses were observed in 14 out of 121 (11%). At present, data on advanced endometrial carcinoma are limited: only 18 treated patients are reported, of whom 7 responded (38.8%). However, in general, most of the responses observed were transient. Thus, so far, the use of GnRH-A in gynecologic oncology has to be considered for palliation, after the failure of other better understood treatment modalities. The possible use of GnRH-A as an adjuvant is still under investigation.