Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie Cancer Center, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
Int J Oncol. 2012 Jun;40(6):1889-99. doi: 10.3892/ijo.2012.1392. Epub 2012 Feb 29.
The Ets proteins are a family of transcription factors characterized by an evolutionarily conserved DNA binding domain that controls key cellular processes. Prostate-derived Ets transcription factor (PDEF), a member of the Ets family, is reported to be present in tissues with high epithelial content, notably breast and prostate. However, the role of PDEF in cancer development is not fully understood. To gain insight into the molecular mechanisms associated with prostate cancer progression, we employed iTRAQ labeling followed by mass spectrometric (MS) analysis to identify candidate proteins that are differentially expressed in prostate cancer cells with or without PDEF. To this end, we overexpressed PDEF in PC3 human prostate cells using a tetracycline inducible system (Tet-On). Many differentially expressed proteins which play important roles in various cellular and biological processes were identified. Among them, stathmin (STMN), which is a microtubule (MT)-destabilizing protein, was found to be downregulated in multiple analyses. We demonstrated that re-expression of STMN reversed the antitumor properties of PDEF in PDEF-overexpressing PC3 cells. Using in vitro functional assays, we showed that STMN overexpression counteracted PDEF's effects against cell proliferation, colony formation and tumor migration. Similar results were further confirmed with the prostate cancer cell line CWR22rv1. In conclusion, many differentially expressed proteins were identified and STMN was found to be downregulated by PDEF. These results suggest that PDEF may inhibit prostate cancer progression by transcriptional downregulation of oncogenic STMN expression. Analyzing the association among differentially expressed proteins may provide a basis to better understand the molecular mechanisms underlying the process of cancer progression and development and further aid in designing therapeutics in the future.
Ets 蛋白家族是一类转录因子，其特征是具有进化上保守的 DNA 结合结构域，可控制关键的细胞过程。前列腺衍生的 Ets 转录因子（PDEF）是 Ets 家族的一员，据报道存在于高上皮含量的组织中，特别是乳腺和前列腺。然而，PDEF 在癌症发展中的作用尚未完全了解。为了深入了解与前列腺癌进展相关的分子机制，我们采用 iTRAQ 标记结合质谱（MS）分析方法，鉴定在有或没有 PDEF 的前列腺癌细胞中差异表达的候选蛋白。为此，我们使用四环素诱导系统（Tet-On）在 PC3 人前列腺细胞中过表达 PDEF。鉴定出许多在各种细胞和生物学过程中发挥重要作用的差异表达蛋白。其中，微管（MT）解聚蛋白 stathmin（STMN）在多种分析中发现下调。我们证明，STMN 的重新表达逆转了 PDEF 在过表达 PDEF 的 PC3 细胞中的抗肿瘤特性。通过体外功能测定，我们表明 STMN 的过表达抵消了 PDEF 对细胞增殖、集落形成和肿瘤迁移的作用。在前列腺癌细胞系 CWR22rv1 中进一步证实了类似的结果。总之，鉴定出许多差异表达蛋白，发现 STMN 被 PDEF 下调。这些结果表明，PDEF 可能通过转录下调致癌 STMN 表达来抑制前列腺癌的进展。分析差异表达蛋白之间的关联可能为更好地理解癌症进展和发展的分子机制提供基础，并有助于未来设计治疗方法。
