Laboratory for Cancer Ontogeny and Therapeutics, Department of Biological Sciences, University of Delaware, Newark, Delaware, USA.
Prostate. 2012 Sep 1;72(12):1339-50. doi: 10.1002/pros.22482. Epub 2012 Jan 6.
Elevated TGF-β levels are associated with prostate cancer progression. Although TGF-β is a tumor suppressor for normal epithelial and early-stage cancer cells, it may act paradoxically as a tumor promoter in more advanced cancers, although its effects are largely cell and context dependent. This study analyzed prostate cancer responses to TGF-β signaling in an isogenic model of androgen-sensitive and castration-resistant prostate cancer cells.
Phosphorylation and nuclear translocation of Smad2 and Smad3 were analyzed using immunoblotting. Proliferation and cell cycle responses to TGF-β1 (5 ng/ml) were assessed using growth assays and flow cytometry for DNA content, as well as Western blot and immunoprecipitation of cell cycle proteins.
Both androgen-sensitive (LNCaP) and castration-resistant (C4-2 and C4-2B) prostate cancer cell lines demonstrated TGF-β1-induced phosphorylation and nuclear translocation of Smad2/3 that was robust in metastatic lines. Smad phosphorylation was completely abrogated with inhibition of ALK-5 kinase activity using the kinase inhibitor, SB-431542. Increased sensitivity to TGF-β1-mediated growth inhibition was observed in C4-2 and C4-2B cells, as compared to LNCaP cells. This was paralleled with downregulation of Cyclin D and increased association of p15(Ink4b) or p27(Kip) with CDK's. Additionally, TGF-β1 inhibited motility and invasion of metastatic cell lines.
TGF-β-mediated suppression of growth and motility is enhanced in metastatic, castration-resistant prostate cancer cells. Enhanced TGF-β1-induced Smad2 and -3 signaling in prostate cancer cells may correlate with tumor suppressive activity. Therefore, the direct effects of TGF-β1 on prostate cancer cells post-castration may be anti-tumorigenic and growth-suppressive.
TGF-β 水平升高与前列腺癌进展有关。虽然 TGF-β 是正常上皮细胞和早期癌细胞的肿瘤抑制因子，但在更晚期的癌症中，它可能表现出矛盾的促肿瘤作用，尽管其作用在很大程度上取决于细胞和环境。本研究分析了 TGF-β 信号在雄激素敏感和去势抵抗前列腺癌细胞的同源模型中对前列腺癌的反应。
使用免疫印迹法分析 Smad2 和 Smad3 的磷酸化和核易位。使用生长测定法和用于 DNA 含量的流式细胞术以及细胞周期蛋白的 Western blot 和免疫沉淀来评估 TGF-β1（5ng/ml）对增殖和细胞周期的反应。
雄激素敏感（LNCaP）和去势抵抗（C4-2 和 C4-2B）前列腺癌细胞系均显示 TGF-β1 诱导 Smad2/3 的磷酸化和核易位，在转移性系中该作用很强。ALK-5 激酶活性的抑制剂 SB-431542 完全阻断 Smad 磷酸化。与 LNCaP 细胞相比，C4-2 和 C4-2B 细胞对 TGF-β1 介导的生长抑制更为敏感。这与 Cyclin D 的下调和 p15(Ink4b)或 p27(Kip)与 CDK 的结合增加相平行。此外，TGF-β1 抑制了转移性细胞系的迁移和侵袭。
在转移性去势抵抗前列腺癌细胞中，TGF-β 介导的生长和迁移抑制增强。增强的 TGF-β1 诱导的前列腺癌细胞中的 Smad2 和 -3 信号可能与肿瘤抑制活性相关。因此，去势后 TGF-β1 对前列腺癌细胞的直接作用可能具有抗肿瘤和生长抑制作用。
