Effect of leuprolide and cetrorelix on cell growth, apoptosis, and GnRH receptor expression in primary cell cultures from human prostate carcinoma.
Contradictory data have been reported regarding the effect of GnRH agonists and antagonists on cell growth and survival, using prostate cancer-derived cell lines expressing either endogenous or exogenous GnRH receptors. We addressed the issue studying the effect of leuprolide (agonist) and cetrorelix (antagonist) on cell growth, apoptosis and GnRH receptor expression using a primary cell coculture system. Also, binding characteristics of prostate GnRH receptor in this culture system are described. Epithelial and stromal cells were obtained from prostate adenocarcinoma samples and cocultured in a bicameral system. Expression of GnRH receptors was evaluated by semiquantitative RT-PCR (transcript level) and Western blot (protein level). Cell growth was estimated by MTT method and apoptosis by DNA fragmentation using COMET assay. Saturation and competition binding studies were carried out using 125I-GnRH as radioligand. GnRH receptors from cell cultures of prostate cancer exhibited a single class of binding sites with a Kd of 1.11 +/- 0.28 nM and a Bmax of 2.81 +/- 0.37 pmol/mg of membrane protein for GnRH. Leuprolide and cetrorelix showed no effect on GnRH receptor expression. Both analogues showed a significant reduction in cell growth rate and an increase in DNA-fragmented cell number. These effects were dependent on the analogue concentrations (from 5-20 ng/mL). Considering that the culture system used in this work represents more closely the in vivo conditions of tumor cells than metastatic derived cell lines, we conclude that GnRH analogues have a significant inhibitory effect on cell viability of cells expressing GnRH receptors. In addition, GnRH receptors expressed in tumor prostatic cells seem not discriminate between agonist and antagonist, both analogues activating these receptors. Also, leuprolide and cetrorelix treatments did not influence GnRH receptor expression in our culture system. These differences with pituitary receptors may be explained by differences in affinity, transduction mechanism and molecular context in prostatic tissue.
Castellón
Enrique
E
Physiology and Biophysics Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile. ecastell@med.uchile.cl
Clementi
Marisa
M
Hitschfeld
Catalina
C
Sánchez
Catherine
C
Benítez
Dixan
D
Sáenz
Leonardo
L
Contreras
Héctor
H
Huidobro
Christian
C
D000230:Adenocarcinoma / Q000188:drug therapy*; D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D020552:Comet Assay; D004847:Epithelial Cells / Q000187:drug effects; D006727:Hormone Antagonists / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D016729:Leuprolide / Q000494:pharmacology*; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D011966:Receptors, LHRH / Q000096:biosynthesis / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000187:drug effects
D018931:Antineoplastic Agents, Hormonal; D006727:Hormone Antagonists; D011966:Receptors, LHRH; D016729:Leuprolide