Weiss-Messer Esther, Merom Osnat, Adi Ayala, Karry Rachel, Bidosee Maslama, Ber Rosalie, Kaploun Alexander, Stein Avi, Barkey Ronnie J
Department of Pharmacology, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Technion, P.O.B. 9649, Haifa 31096, Israel.
Mol Cell Endocrinol. 2004 May 31;220(1-2):109-23. doi: 10.1016/j.mce.2004.03.004.
Various hormones and growth factors have been implicated in progression of prostate cancer, but their role and the underlying molecular mechanism(s) involved remain poorly understood. In this study, we investigated the role of human growth hormone (GH) and its receptor (GHR) in human prostate cancer. We first demonstrated mRNA expression of GHR and of its exon 9-truncated isoform (GHR(tr)) in benign prostate hyperplasia (BPH) and prostate adenocarcinoma patient tissues, as well as in LNCaP, PC3 and DU145 human prostate cancer cell lines. GHR mRNA levels were 80% higher and GHR(tr) only 25% higher, in the carcinoma tissues than in BPH. Both isoforms were also expressed in LNCaP and PC3 cell lines and somewhat less so in DU145 cells. The LNCaP cell GHR protein was further characterized, on the basis of its M(r) of 120kDa, its binding to two different GHR monoclonal antibodies, its high affinity and purely somatogenic binding to (125)I-hGH and its ability to secrete GH binding protein, all characteristic of a functional GHR. Furthermore, GH induced rapid, time- and dose-dependent signaling events in LNCaP cells, including phosphorylation of JAK2 tyrosine kinase, of GHR itself and of STAT5A (JAK2-STAT5A pathway), of p42/p44 MAPK and of Akt/PKB. No effect of GH (72h) could be shown on basal or androgen-induced LNCaP cell proliferation nor on PSA secretion. Interestingly, however, GH caused a rapid (2-12h) though transient striking increase in immunoreactive androgen receptor (AR) levels (< or =5-fold), followed by a slower (24-48h) reduction (< or = 80%), with only modest parallel changes in serine-phosphorylated AR. In conclusion, the GH-induced activation of signaling pathways, its effects on AR protein in LNCaP cells and the isoform-specific regulation of GHR in prostate cancer patient tissues, suggest that GH, most likely in concert with other hormones and growth factors, may play an important role in progression of human prostate cancer.
多种激素和生长因子与前列腺癌的进展有关，但其作用及所涉及的潜在分子机制仍了解甚少。在本研究中，我们调查了人生长激素（GH）及其受体（GHR）在人前列腺癌中的作用。我们首先证实了GHR及其外显子9截短异构体（GHR(tr)）在良性前列腺增生（BPH）和前列腺腺癌患者组织以及LNCaP、PC3和DU145人前列腺癌细胞系中的mRNA表达。癌组织中GHR mRNA水平比BPH高80%，而GHR(tr)仅高25%。两种异构体在LNCaP和PC3细胞系中也有表达，在DU145细胞中表达稍少。基于其120kDa的相对分子质量、与两种不同GHR单克隆抗体的结合、与(125)I-hGH的高亲和力和纯促生长结合以及分泌GH结合蛋白的能力，对LNCaP细胞的GHR蛋白进行了进一步表征，所有这些都是功能性GHR的特征。此外，GH在LNCaP细胞中诱导了快速、时间和剂量依赖性的信号转导事件，包括JAK2酪氨酸激酶、GHR自身以及STAT5A（JAK2-STAT5A途径）、p42/p44 MAPK和Akt/PKB的磷酸化。未显示GH（72小时）对基础或雄激素诱导的LNCaP细胞增殖以及PSA分泌有影响。然而，有趣的是，GH导致免疫反应性雄激素受体（AR）水平迅速（2-12小时）但短暂显著升高（≤5倍），随后缓慢（24-48小时）降低（≤80%），丝氨酸磷酸化AR仅有适度的平行变化。总之，GH诱导的信号通路激活、其对LNCaP细胞中AR蛋白的影响以及前列腺癌患者组织中GHR的异构体特异性调节表明，GH很可能与其他激素和生长因子协同作用，可能在人前列腺癌的进展中起重要作用。
