Horvath Lisa G, Henshall Susan M, Kench James G, Saunders Darren N, Lee C-Soon, Golovsky David, Brenner Phillip C, O'Neill Gordon F, Kooner Raji, Stricker Phillip D, Grygiel John J, Sutherland Robert L
Cancer Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Darlinghurst, Sydney, New South Wales, Australia.
Clin Cancer Res. 2004 Jan 15;10(2):615-25. doi: 10.1158/1078-0432.ccr-0707-03.
Activation of the Wnt-signaling pathway is implicated in aberrant cellular proliferation in a variety of cancers. Secreted frizzled-related protein 4 (sFRP4) is a secreted protein with putative inhibitory activity of the Wnt-signaling cascade through binding and sequestering Wnt ligands. Because sFRP4 mRNA is overexpressed in prostate cancers (PCs), the aim of this study was to define the pattern of sFRP4 protein expression in normal and malignant human prostate tissue and to determine whether changes in expression were associated with disease progression and prognosis, as well as to define the phenotype of sFRP4-overexpression in an in vitro model of PC.
Polyclonal antibodies were raised against a COOH-terminal peptide of sFRP4, characterized and used to assess sFRP4 protein expression in benign prostate tissue and 229 patients with clinically localized PC (median follow-up 77 months, range 1-156). In vitro studies of the function of sFRP4 overexpression were performed using PC3 cells transfected with sFRP4.
Benign and malignant prostate tissue demonstrated cytoplasmic sFRP4 immunoreactivity, but there was a decrease in the expression of membranous sFRP4 in PCs compared with the hyperplastic lesions (P < 0.0001). Kaplan-Meier analysis revealed that patients whose PC expressed membranous sFRP4 in >20% of cells had improved relapse-free survival compared with those with </=20% membranous expression (P = 0.002). Moreover, membranous sFRP4 expression (P = 0.04) was an independent predictor of relapse when modeled with Gleason score (P = 0.006), pathological stage (P = 0.002), and pre-operative prostate-specific antigen levels (P = 0.004). In addition, in vitro studies demonstrated a decrease in the proliferation rate of PC3 cells transfected with sFRP4 when compared with the control PC3-empty vector cells (P < 0.0001). Decreased levels of phosphorylated glycogen synthase kinase 3beta in PC3-sFRP4 cells suggested that this phenotype is mediated by the "Wnt/beta-catenin" pathway.
These data suggest that sFRP4 expression may be prognostic for localized PC, potentially as a consequence of an inhibitory effect on PC cell proliferation.
Wnt信号通路的激活与多种癌症中异常的细胞增殖有关。分泌型卷曲相关蛋白4（sFRP4）是一种分泌蛋白，通过结合和隔离Wnt配体对Wnt信号级联反应具有假定的抑制活性。由于sFRP4 mRNA在前列腺癌（PC）中过表达，本研究的目的是确定sFRP4蛋白在正常和恶性人前列腺组织中的表达模式，确定表达变化是否与疾病进展和预后相关，并在PC的体外模型中确定sFRP4过表达的表型。
制备针对sFRP4羧基末端肽的多克隆抗体，对其进行表征并用于评估良性前列腺组织和229例临床局限性PC患者（中位随访77个月，范围1 - 156个月）中sFRP4蛋白的表达。使用转染了sFRP4的PC3细胞进行sFRP4过表达功能的体外研究。
良性和恶性前列腺组织均显示细胞质sFRP4免疫反应性，但与增生性病变相比，PC中膜性sFRP4的表达降低（P < 0.0001）。Kaplan-Meier分析显示，PC中膜性sFRP4在>20%的细胞中表达的患者与膜性表达≤20%的患者相比，无复发生存率有所提高（P = 0.002）。此外，当与Gleason评分（P = 0.006）、病理分期（P = 0.002）和术前前列腺特异性抗原水平（P = 0.004）一起建模时，膜性sFRP4表达（P = 0.04）是复发的独立预测因子。此外，体外研究表明，与对照PC3空载体细胞相比，转染了sFRP4的PC3细胞的增殖率降低（P < 0.0001）。PC3 - sFRP4细胞中磷酸化糖原合酶激酶3β水平降低表明该表型由“Wnt/β-连环蛋白”途径介导。
这些数据表明sFRP4表达可能对局限性PC具有预后价值，这可能是对PC细胞增殖产生抑制作用的结果。
