Androgens regulate protein kinase Cδ transcription and modulate its apoptotic function in prostate cancer cells
Androgens regulate protein kinase Cδ transcription and modulate its apoptotic function in prostate cancer cells
复制标题
DOI：
10.1158/0008-5472.can-06-1139
复制
发表时间：
2006-12-15
期刊：
影响因子：
11.2
通讯作者：
Kazanietz, Marcelo G.
中科院分区：
文献类型：
--
作者：
Gavrielides, M. Veronica;Gonzalez-Guerrico, Anatilde M.;Kazanietz, Marcelo G.
蛋白激酶C增量(PKC Delta)是新的PKC家族成员之一，它的激活可导致多种细胞类型的凋亡。虽然PKC Delta激活的分子基础正在被揭开，但关于其表达的控制机制的信息有限。在这里，我们报告了在前列腺癌细胞中，PKC Delta在转录水平上受到雄激素的严格调控。培养上清液中的类固醇耗尽导致雄激素敏感的LNCaP前列腺癌细胞中PKC Delta蛋白和mRNA的显著下调，这一效应可被雄激素R1881以雄激素受体(AR)依赖的方式拯救。对PKC Delta启动子的分析显示，在转录起始点的上游有一个可能的雄激素反应元件(ARE)。荧光素酶报告分析表明，该元件对雄激素高度敏感，在所有结合共识中的关键核苷酸突变取消了报告活性。此外，利用染色质免疫沉淀分析，我们确定体内AR与PKC增量的结合是对雄激素刺激的反应。功能研究表明，雄激素调节佛波醇12-肉豆蔻酸酯13-醋酸酯(PMA)诱导的LNCaP细胞凋亡，这种作用依赖于PKC增量。事实上，雄激素耗竭或AR RNA干扰严重损害了PKC Delta的凋亡功能或激活了LNCaP细胞中PKC Delta的下游效应因子p38--这些效应可以通过使用腺病毒传递方法恢复PKC Delta的水平来挽救。我们的研究发现了一种新的激素机制，通过转录调控微调PKC Delta凋亡反应的幅度来控制PKC Delta的表达。
Activation of protein kinase C delta (PKC delta), a member of the novel PKC family, leads to apoptosis in several cell types. Although the molecular bases of PKC delta activation are being unfolded, limited information is available on the mechanisms that control its expression. Here, we report that in prostate cancer cells PKC delta is tightly regulated by androgens at the transcriptional level. Steroid depletion from the culture medium causes a pronounced down-regulation of PKC delta protein and mRNA in androgen-sensitive LNCaP prostate cancer cells, an effect that is rescued by the androgen R1881 in an androgen receptor (AR)-dependent manner. Analysis of the PKC delta promoter revealed a putative androgen responsive element (ARE) located 4.7 kb upstream from the transcription start site. Luciferase reporter assays show that this element is highly responsive to androgens, and mutations in key nucleotides in the All-binding consensus abolish reporter activity. Furthermore, using chromatin immunoprecipitation assays, we determined that the AR binds in vivo to the PKC delta ARE in response to androgen stimulation. Functional studies revealed that, notably, androgens modulate phorbol 12-myristate 13-acetate (PMA)-induced apoptosis in LNCaP cells, an effect that is dependent on PKC delta. Indeed, androgen depletion or AR RNA interference severely impaired the apoptotic function of PKC delta or the activation of p38, a downstream effector of PKC delta in LNCaP cells-effects that can be rescued by restoring PKC delta levels using an adenoviral delivery approach. Our studies identified a novel hormonal mechanism for the control of PKC delta expression via transcriptional regulation that fine-tunes the magnitude of PKC delta apoptotic responses.