Department of Urology, University Medicine Greifswald, Greifswald, Germany.
Department of Psychiatry, Psychosomatics and Psychotherapy, University Hospital of Frankfurt, Frankfurt, Germany.
J Cell Biochem. 2019 Oct;120(10):16711-16722. doi: 10.1002/jcb.28929. Epub 2019 Jul 11.
Enzalutamide's accepted mode of action is by targeting the androgen receptor's (AR) activity. In clinical practice, enzalutamide demonstrates a good benefit-risk profile for the treatment of advanced prostate cancer (PC), even after poor response to standard antihormonal treatment. However, since both, well-established antiandrogens and enzalutamide, target AR functionality, we hypothesized that additional unknown mechanisms might be responsible for enzalutamide's superior anticancer activity. In the current study, PC cells were incubated with enzalutamide and enzalutamide-dependent modulation of apoptotic mechanisms were assessed via Western blot analysis, TDT-mediated dUTP-biotin nick end-labeling assay, and nuclear morphology assay. Alterations of heat shock protein (HSP), AR, and estrogen receptor (ER) expression were examined by Western blot analysis. Enzalutamide attenuated the proliferation of PC cells in a time- and dose-dependent manner. In the presence of enzalutamide, apoptosis occurred which was shown by increased BAX expression, decreased Bcl-2 expression, nuclear pyknosis, and genomic DNA fragmentation. Moreover, enzalutamide inhibited the expression of HSPs primarily involved in steroid receptor stabilization and suppressed AR and ERβ1 expression. This study demonstrates for the first time that enzalutamide treatment of PC cells triggers varying molecular mechanisms resulting in antiproliferative effects of the drug. In addition to the well-characterized antagonistic inhibition of AR functionality, we have shown that enzalutamide also affects the intracellular synthesis of steroid receptor-associated HSPs, thereby diminishing the expression of AR and ERβ1 proteins and inducing apoptotic pathways. According to an indirect attenuation of HSP-associated factors such as steroid receptors, endometrial carcinoma, uterine leiomyosarcoma, and mamma carcinoma cells also demonstrated inhibited cell growth in the presence of enzalutamide. Our data, therefore, suggest that enzalutamide's high efficacy is at least partially independent of AR and p53 protein expression, which are frequently lost in advanced PC.
恩杂鲁胺的作用模式是通过靶向雄激素受体 (AR) 的活性。在临床实践中，即使在对标准抗激素治疗反应不佳的情况下，恩杂鲁胺在治疗晚期前列腺癌 (PC) 方面也具有良好的获益风险比。然而，由于已确立的抗雄激素药物和恩杂鲁胺均靶向 AR 功能，我们假设可能存在其他未知机制负责恩杂鲁胺的优越抗癌活性。在本研究中，将 PC 细胞与恩杂鲁胺孵育，并通过 Western blot 分析、TDT 介导的 dUTP-生物素 nick 末端标记测定和核形态测定评估恩杂鲁胺依赖性凋亡机制的调节。通过 Western blot 分析检测热休克蛋白 (HSP)、AR 和雌激素受体 (ER) 的表达变化。恩杂鲁胺呈时间和剂量依赖性方式减弱 PC 细胞的增殖。在恩杂鲁胺存在的情况下，发生凋亡，这表现为 BAX 表达增加、Bcl-2 表达减少、核固缩和基因组 DNA 片段化。此外，恩杂鲁胺抑制主要参与类固醇受体稳定的 HSPs 的表达，并抑制 AR 和 ERβ1 的表达。本研究首次证明，恩杂鲁胺治疗 PC 细胞会触发多种分子机制，从而导致药物的抗增殖作用。除了众所周知的拮抗 AR 功能抑制作用外，我们还表明，恩杂鲁胺还影响与类固醇受体相关的 HSP 的细胞内合成，从而减少 AR 和 ERβ1 蛋白的表达并诱导凋亡途径。根据 HSP 相关因子（如类固醇受体）的间接衰减，在恩杂鲁胺存在的情况下，子宫内膜癌、子宫平滑肌肉瘤和乳腺癌细胞的生长也受到抑制。因此，我们的数据表明，恩杂鲁胺的高疗效至少部分独立于 AR 和 p53 蛋白表达，这些蛋白在晚期 PC 中经常丢失。
