lhrh--his(5)-trp(7)-tyr(8)- and Endometrial-Neoplasms

Type I gonadotropin-releasing hormone (GnRH-I) agonists have been applied for the treatment of steroid-dependent tumors such as breast carcinoma, ovarian cancer and prostatic carcinoma. But the mechanism has not been clarified yet. There are few reports about the treatment of endometrial carcinoma using GnRH-I agonists. Type II GnRH (GnRH-II) is a new subtype of GnRH. Our aim was to investigate the effects of GnRH-I agonists and GnRH-II on estrogen receptor-negative human endometrial carcinoma cells and the effect from phosphatase and tensin homolog gene (PTEN) to them.. A lentiviral vector-mediated RNAi method was used to establish a PTEN-negative HEC-1A cell clone (HEC-1A-ND). MTT and flow cytometry were used to detect the cell proliferation, cell cycle and apoptosis of HEC-1A, HEC-1A-NC and HEC-1A-ND cells after treatment with GnRH-I agonist Triptorelin (10(-11) mol/L to 10(-5) mol/L) or GnRH-II (10(-11) mol/L to 10(-5) mol/L). Western blotting was used to detect AKT and ERK1/2 activation after treatment with different concentrations of Triptorelin or GnRH-II for 30 minutes in the above mentioned three kinds of cells.. Triptorelin and GnRH-II induced apoptosis and inhibited proliferation of HEC-1A, HEC-1A-ND and HEC-1A-NC in a dose-dependent manner. This effect was augmented in HEC-1A-ND cells in which PTEN gene was knocked-down. Furthermore, Triptorelin and GnRH-II inhibited the AKT and ERK activity in HEC-1A-ND cells.. Triptorelin and GnRH-II can promote apoptosis rate and inhibit cell proliferation of estrogen receptor-negative endometrial carcinoma cells in a dose-dependent manner. PTEN gene can inhibit the effects of Triptorelin or GnRH-II on human endometrial carcinoma cells.

Topics: Apoptosis; Blotting, Western; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Endometrial Neoplasms; Female; Gonadotropin-Releasing Hormone; Humans; PTEN Phosphohydrolase; RNA Interference; Triptorelin Pamoate

Gonadotropin-releasing hormone type II (GnRH-II) has an antiproliferative effect on human endometrial cancer cells. Apoptosis in cancer cells may play a critical role in regulating cell proliferation. However, more studies are necessary to elucidate the underlying molecular mechanisms and develop potential applications of GnRH-II. Therefore, we explored the mechanisms of GnRH-II-induced apoptosis and the effects of GnRH-II on GADD45alpha activation in human endometrial cancer cell lines. GnRH-II decreased cell viability in a dose- and time-dependent manner. Apoptosis was induced with increased terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling apoptotic cells after GnRH-II treatment. Knockdown of the endogenous GnRH-I receptor with small interfering RNA (siRNA) rescued the cells from GnRH-II-mediated cell growth inhibition and abolished the induction of apoptosis. GnRH-II activated extracellular signal-regulated kinase (ERK)-1/2 and p38 mitogen-activated protein kinase (MAPK) in a time-dependent manner, and the activation was abolished by GnRH-I receptor siRNA and MAPK inhibitors. Cells pretreated with MAPK inhibitors were rescued from GnRH-II-mediated cell growth inhibition. Moreover, both inhibitors abolished GnRH-II-induced apoptosis. GnRH-II induced GADD45alpha expression, which was abolished by knockdown of endogenous GnRH-I receptors and MAPK inhibitors. GnRH-II-stimulated cell growth inhibition was rescued by knockdown of endogenous GADD45alpha with siRNA. Cells treated with GADD45alpha siRNA were refractory to GnRH-II-induced apoptosis. Thus, GnRH-II inhibits cell growth by inducing apoptosis through binding of the GnRH-I receptor, activation of the ERK1/2 and p38 MAPK pathways, and induction of GADD45alpha signaling. This finding may provide a new concept relating to the mechanism of GnRH-II-induced antiproliferation and apoptosis in endometrial cancer cells, indicating the possibility of GnRH-II as a promising therapeutic intervention for human endometrial cancer.

Topics: Apoptosis; Cell Division; Cell Line, Tumor; Cell Survival; Endometrial Neoplasms; Female; Gonadotropin-Releasing Hormone; Humans; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Receptors, LHRH; RNA, Small Interfering; Transfection

Recently, we could show that gonadotropin-releasing hormone (GnRH)-II antagonists induce apoptosis in human endometrial, ovarian, and breast cancer cells in vitro and in vivo. In the present study, we have ascertained receptor binding and effects of GnRH-II antagonists on mitogenic signal transduction and on activation of proapoptotic protein Bax. The GnRH-II antagonists tested showed EC50 values for GnRH-I receptor binding in the range of 1 to 2 nmol/L. The GnRH-II agonist [D-Lys6]GnRH-II showed an EC50 value for GnRH-I receptor binding of approximately 1,000 nmol/L. Agonistic activity on GnRH-I receptor function with an EC50 of 13 nmol/L has been determined for [D-Lys6]GnRH-II. Antagonistic activities with EC50 values in the range of 1 nmol/L were determined for the GnRH-II antagonists. Treatment of human endometrial, ovarian, and breast cancer cells with GnRH-II antagonists resulted in time-dependent activation of stress-induced mitogen-activated protein kinases p38 and c-Jun NH2-terminal kinase. In addition, treatment with GnRH-II antagonists induced time-dependent activation of proapoptotic protein Bax. GnRH-II antagonists are not involved in activation of protein kinase B/Akt or extracellular signal-regulated kinase 1/2. The GnRH-II antagonists tested had similar binding affinities to the GnRH-I receptor comparable with that of GnRH-I antagonist Cetrorelix. Referring to the cyclic AMP response element reporter gene activation assay, the GnRH-II agonist [D-Lys6]GnRH-II has to be classified as an agonist at the GnRH-I receptor, whereas the GnRH-II antagonists tested are clear antagonists at the GnRH-I receptor. GnRH-II antagonists induce apoptotic cell death in human endometrial, ovarian, and breast cancer cells via activation of stress-induced mitogen-activated protein kinases p38 and c-Jun NH2-terminal kinase followed by activation of proapoptotic protein Bax.

Topics: Antineoplastic Agents, Hormonal; Apoptosis; bcl-2-Associated X Protein; Breast Neoplasms; Endometrial Neoplasms; Enzyme Activation; Female; Gonadotropin-Releasing Hormone; Hormone Antagonists; Humans; JNK Mitogen-Activated Protein Kinases; Ovarian Neoplasms; p38 Mitogen-Activated Protein Kinases; Protein Binding; Receptors, LHRH; Tumor Cells, Cultured

Endometrial carcinoma is the most common neoplasm of the female genital tract, accounting for nearly one half of all gynecologic cancers in the Western world. Although intensive research on pathological phenomena of endometrial cancer is currently going on, but exact cause and biological aspects of this disease are not well described yet. In addition to well-documented roles of gonadotropin-releasing hormone (GnRH) in hypopituitary ovarian (HPO) axis, the agonistic or antagonistic analogs (or both) of GnRH have been shown to inhibit the proliferation of a variety of human gynecologic cancers. Thus, in the present study, we further examined the possibility that GnRH induces integrin beta3 and activation of focal adhesion kinase (FAK) through mitogen-activated protein kinases (MAPKs), ERK1/2 and p38, to inhibit the growth of HEC1A endometrial cancer cell line. As a result, both GnRH-I and GnRH-II resulted in a significant increase in integrin beta3 expression and evoked the activation of FAK in a time-dependent manner in these cells. In addition, these analogs induced an activation of ERK1/2 and p38 MAPK in a time-dependent manner as downstream pathways of FAK. It appears that GnRH-II has much greater effect on the activation of FAK, ERK1/2 and p38 compared to GnRH-I in these cells. Further, we demonstrated that the growth inhibition of HEC1A cells by GnRH-I or GnRH-II is involved in the activation of integrin-FAK and ERK1/2 and p38 MAPK pathways. Taken together, these results suggest that GnRH may be involved in the inhibition of endometrial cancer cell growth via activation of integrin beta3 and FAK as a direct effect. This knowledge could contribute to a better understanding of the mechanisms implicated in the therapeutic action of GnRH and its biomedical application for the treatment against endometrial cancer.

Topics: Blotting, Western; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Endometrial Neoplasms; Enzyme Activation; Enzyme Inhibitors; Female; Focal Adhesion Protein-Tyrosine Kinases; Gonadotropin-Releasing Hormone; Humans; Imidazoles; Integrin beta3; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; p38 Mitogen-Activated Protein Kinases; Protein Precursors; Pyridines; Signal Transduction

In human endometrial and ovarian cancers, gonadotropin-releasing hormone type I (GnRH-I), GnRH-II, and their receptors are parts of a negative autocrine regulatory system of cell proliferation. Based on a tumor-specific signal transduction, GnRH-I and GnRH-II agonists inhibit the mitogenic signal transduction of growth factor receptors and related oncogene products associated with tyrosine kinase activity via activation of a phosphotyrosine phosphatase resulting in down-regulation of cancer cell proliferation. Induction of apoptosis is not involved. In this study, we show that treatment of human endometrial and ovarian cancer cells with GnRH-II antagonists results in apoptotic cell death via dose-dependent activation of caspase-3. The antitumor effects of the GnRH-II antagonists could be confirmed in nude mice. GnRH-II antagonists inhibited the growth of xenotransplants of human endometrial and ovarian cancers in nude mice significantly, without any apparent side effects. Thus, GnRH-II antagonists seem to be suitable drugs for an efficacious and less toxic endocrine therapy for endometrial and ovarian cancers.

Topics: Animals; Apoptosis; Caspase 3; Cell Growth Processes; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Interactions; Endometrial Neoplasms; Enzyme Activation; Female; Gonadotropin-Releasing Hormone; Humans; Membrane Potential, Mitochondrial; Mice; Mice, Nude; Ovarian Neoplasms; Pertussis Toxin; Receptors, LHRH; Xenograft Model Antitumor Assays

The majority of human endometrial and ovarian cancer cell lines express receptors for GnRH. Their proliferation is time- and dose-dependently reduced by GnRH-I and its superagonistic analogues. Recently, we have demonstrated that, in human endometrial and ovarian cancer cell lines except for the ovarian cancer cell line EFO-27, the GnRH-I antagonist cetrorelix has antiproliferative effects comparable to those of GnRH-I agonists, indicating that the dichotomy between GnRH-I agonists and antagonists might not apply to the GnRH system in cancer cells. We were also able to show that the proliferation of human endometrial and ovarian cancer cells was dose- and time-dependently reduced by GnRH-II to a greater extent than by GnRH-I agonists.. In this study we have assessed whether or not the antiproliferative effects of the GnRH-I antagonist cetrorelix in endometrial and ovarian cancer cells are mediated through the GnRH-I receptor.. We analysed the antiproliferative effects of the GnRH-I agonist triptorelin, the GnRH-I antagonist cetrorelix and GnRH-II in a panel of endometrial and ovarian cancer cell lines expressing GnRH-I receptors, in the SK-OV-3 ovarian cancer cell line that does not express GnRH-I receptors, and in four GnRH-I receptor positive GnRH-I receptor knockout cell lines.. We found that, after knockout of the GnRH-I receptor, the antiproliferative effects of the GnRH-I agonist triptorelin were abrogated, whereas those of the GnRH-I antagonist cetrorelix and of GnRH-II persisted.. These data suggest that, in endometrial and ovarian cancer cells, the antiproliferative effects of cetrorelix and of GnRH-II are not mediated through the GnRH-I receptor.

Topics: Antineoplastic Agents, Hormonal; Cell Division; Cell Line, Tumor; Endometrial Neoplasms; Female; Gonadotropin-Releasing Hormone; Hormone Antagonists; Humans; Mutagenesis; Ovarian Neoplasms; Receptors, LHRH; Triptorelin Pamoate

Recently it was shown that a second GnRH system exists in primates. This study was conducted to investigate whether or not the receptor specific for GnRH type II is expressed in human endometrial and ovarian cancer cells and whether or not GnRH-II has effects on tumor cell proliferation. Expression of GnRH-II receptor mRNA in endometrial and ovarian cancer cell lines was demonstrated using RT-PCR and Southern blot analysis. The proliferation of these cell lines was dose- and time-dependently reduced by native GnRH-II. These effects were significantly more potent than the anitproliferative effects of equimolar doses of GnRH-I agonist Triptorelin (p<0.001). In the GnRH-II receptor positive but GnRH-I receptor negative ovarian cancer cell line SK-OV-3 native GnRH-II but not GnRH-I agonist Triptorelin had antiproliferative effects.

Topics: Cell Division; Endometrial Neoplasms; Female; Gonadotropin-Releasing Hormone; Humans; Ovarian Neoplasms; Receptors, LHRH; Triptorelin Pamoate; Tumor Cells, Cultured