Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA.
Prostate. 2011 Dec;71(16):1723-35. doi: 10.1002/pros.21389. Epub 2011 Mar 28.
Ets is a large family of transcriptional regulators with functions in most biological processes. While the Ets family gene, prostate-derived epithelial factor (PDEF), is expressed in epithelial tissues, PDEF protein expression has been found to be reduced or lost during cancer progression. The goal of this study was to examine the mechanism for and biologic impact of altered PDEF expression in prostate cancer.
PDEF protein expression of prostate specimens was examined by immunohistochemistry. RNA and protein expression in cell lines were measured by q-PCR and Western blot, respectively. Cellular growth was determined by quantifying viable and apoptotic cells over time. Cell cycle was measured by flow cytometry. Migration and invasion were determined by transwell assays. PDEF promoter occupancy was determined by chromatin immunoprecipitation (ChIP).
While normal prostate epithelium expresses PDEF mRNA and protein, tumors show no or decreased PDEF protein expression. Re-expression of PDEF in prostate cancer cells inhibits cell growth. PDEF expression is inversely correlated with survivin, urokinase plasminogen activator (uPA) and slug expression and ChIP studies identify survivin and uPA as direct transcriptional targets of PDEF. This study also shows that PDEF expression is regulated via a functional microRNA-204 (miR-204) binding site within the 3'UTR. Furthermore, we demonstrate the biologic significance of miR-204 expression and that miR-204 is over-expressed in human prostate cancer specimens.
Collectively, the reported studies demonstrate that PDEF is a negative regulator of tumor progression and that the miR-204-PDEF regulatory axis contributes to PDEF protein loss and resultant cancer progression.
Ets 是一个具有多种生物学功能的转录调控因子家族。虽然 Ets 家族基因前列腺衍生的上皮因子（PDEF）在上皮组织中表达，但在癌症进展过程中发现 PDEF 蛋白表达减少或丢失。本研究的目的是研究前列腺癌中 PDEF 表达改变的机制及其生物学影响。
通过免疫组织化学检测前列腺标本中的 PDEF 蛋白表达。通过 q-PCR 和 Western blot 分别测量细胞系中的 RNA 和蛋白质表达。通过随时间定量活细胞和凋亡细胞来确定细胞生长。通过流式细胞术测量细胞周期。通过 Transwell 测定法测定迁移和侵袭。通过染色质免疫沉淀（ChIP）测定 PDEF 启动子占有率。
虽然正常前列腺上皮表达 PDEF mRNA 和蛋白，但肿瘤中 PDEF 蛋白表达缺失或减少。在前列腺癌细胞中重新表达 PDEF 可抑制细胞生长。PDEF 表达与 survivin、尿激酶型纤溶酶原激活物（uPA）和 slug 表达呈负相关，ChIP 研究表明 survivin 和 uPA 是 PDEF 的直接转录靶标。本研究还表明，PDEF 表达通过 3'UTR 内的功能性 microRNA-204（miR-204）结合位点进行调节。此外，我们证明了 miR-204 表达的生物学意义，并且 miR-204 在人前列腺癌标本中过表达。
综上所述，报告的研究表明 PDEF 是肿瘤进展的负调节剂，miR-204-PDEF 调节轴有助于 PDEF 蛋白丢失和由此导致的癌症进展。
