Sánchez Catherine, Clementi Marisa, Benitez Dixan, Contreras Héctor, Huidobro Christian, Castellón Enrique
Physiology and Biophysics Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile.
Prostate. 2005 Nov 1;65(3):195-202. doi: 10.1002/pros.20281.
GnRH analogs have antiproliferative and/or apoptotic effects on prostate cancer cells. Also, neurotrophin receptors TrkA and p75 have been reported in normal prostate suggesting a role in the gland growth control. In prostate cancer, TrkA receptors seem to be overexpressed and p75 receptors show a decreased expression. These changes in neurotrophin receptors may be related with unbalanced growth in malignant cells. In the present study we investigate the effects of GnRH analogs (leuprolide and cetrorelix) on the expression of TrkA and p75 neurotrophin receptors in primary cultures of human prostate cancer cells.
Tissue was obtained from radical prostatectomies due to prostate adenocarcinoma. Cells were isolated after sequential enzyme digestion and cultured in defined media. Nerve growth factor (NGF) receptors in untreated cultures were estimated by immunofluorescence. Cultures were treated with leuprolide (agonist) or cetrorelix (antagonist) and expression of TrkA and p75 receptors were evaluated by semi quantitative RT-PCR (polymerase chain reaction) and western blot. Cell proliferation was estimated by MTT method and apoptosis through COMET assay.
Both leuprolide and cetrorelix induced a significant increase in p75 receptor gene and protein expression at a concentration that induce apoptosis and decrease proliferation. TrkA receptors showed no changes in presence of GnRH analogs.
GnRH analogs, leuprolide, and cetrorelix, change the ratio between neurotrophin receptors TrkA and p75 by increasing gene and protein expression of p75 receptor. Considering that TrkA receptor is related with proliferation and p75 with apoptosis, we suggest that our findings may explain, in part, the effect of GnRH analogs on prostate cancer growth.
促性腺激素释放激素（GnRH）类似物对前列腺癌细胞具有抗增殖和/或凋亡作用。此外，已报道在正常前列腺中存在神经营养因子受体TrkA和p75，提示其在腺体生长控制中发挥作用。在前列腺癌中，TrkA受体似乎过度表达，而p75受体表达降低。神经营养因子受体的这些变化可能与恶性细胞生长失衡有关。在本研究中，我们调查了GnRH类似物（亮丙瑞林和西曲瑞克）对人前列腺癌细胞原代培养物中TrkA和p75神经营养因子受体表达的影响。
组织取自因前列腺腺癌而行根治性前列腺切除术的患者。经序贯酶消化后分离细胞，并在特定培养基中培养。通过免疫荧光法评估未处理培养物中的神经生长因子（NGF）受体。用亮丙瑞林（激动剂）或西曲瑞克（拮抗剂）处理培养物，并通过半定量逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法评估TrkA和p75受体的表达。通过MTT法评估细胞增殖，通过彗星试验评估细胞凋亡。
亮丙瑞林和西曲瑞克均在诱导凋亡和降低增殖的浓度下，使p75受体基因和蛋白表达显著增加。在GnRH类似物存在的情况下，TrkA受体未发生变化。
GnRH类似物亮丙瑞林和西曲瑞克通过增加p75受体的基因和蛋白表达，改变了神经营养因子受体TrkA和p75之间的比例。鉴于TrkA受体与增殖相关，而p75与凋亡相关，我们认为我们的发现可能部分解释了GnRH类似物对前列腺癌生长的影响。
