University of Coimbra, Coimbra Institute for Clinical and Biomedical Research (iCBR) area of Environment Genetics and Oncobiology (CIMAGO), Biophysics Institute of Faculty of Medicine, Coimbra, Portugal.
Center for Innovative Biomedicine and Biotechnology (CIBB), Coimbra, Portugal.
Int J Radiat Biol. 2021;97(5):714-726. doi: 10.1080/09553002.2021.1906462. Epub 2021 Apr 7.
Metastatic castration-resistant prostate cancer (mCRPC) is associated with a very unfavorable prognosis. At this advanced stage of the disease, there are several therapeutic strategies approved in recent times, being one of them Radium-223 dichloride (Radium-223). However, its mechanisms of action and the process that conducts to cell death are not fully understood. Given this, our main goal is to characterize the radiobiological effects induced by Radium-223 and to evaluate its kinetics on metastatic Prostate Cancer (mPCa) cells.
In vitro studies were conducted using two mPCa cell lines, the LNCaP and PC3, the first being derived from lymph node metastasis and the second from bone metastasis. Kinetic studies were conducted to access the capacity of these cell lines to uptake, retain and internalize the Radium-223. For the assessment of radiobiological effects, cells were first exposed to different doses of Radium-223 and the clonogenic assay was done to evaluate cell survival and to determine lethal doses (LD50). Then, the effects were also evaluated in terms of proliferation, oxidative stress, morphological changes and cell damage.
Radium-223 is uptaken by mPCa cells and reaches the nucleus, where it is retained over time. Irradiation decreases cell survival and proliferation, with LNCaP cells (LD50 = 1.73mGy) being more radiosensitive than PC3 cells (LD50 = 4.20mGy). Irradiated cells showed morphological changes usually associated with apoptosis and a dose-dependent increase in DNA damage. Moreover, activation of cell cycle checkpoints occurs through ATM/CHK2 pathway, which is involved in cell cycle arrest and cell death.
The cytotoxic and anti-proliferative effects on both cell lines showed that Radium-223 can decrease the aggressiveness of tumor cells by decreasing the cell survival and proliferation and, also, by increasing the DNA damage. The similar results observed in both cell lines indicated that Radium-223 may have the potential to be used as a therapeutic option also for mCRPC patients with lymph node metastasis. The activation of DNA Damage Response pathways allows the possibility to understand the importance of these checkpoints as targets for new combined therapies.
转移性去势抵抗性前列腺癌（mCRPC）预后极差。在疾病的这一晚期阶段，最近有几种治疗策略获得批准，其中一种是镭-223 二氯化物（镭-223）。然而，其作用机制和导致细胞死亡的过程尚不完全清楚。有鉴于此，我们的主要目标是描述镭-223 诱导的放射生物学效应，并评估其对转移性前列腺癌（mPCa）细胞的动力学。
在体外研究中，我们使用两种 mPCa 细胞系，即 LNCaP 和 PC3，前者来自淋巴结转移，后者来自骨转移。我们进行了动力学研究，以评估这些细胞系摄取、保留和内化镭-223 的能力。为了评估放射生物学效应，我们首先使细胞暴露于不同剂量的镭-223，然后进行集落形成实验以评估细胞存活并确定致死剂量（LD50）。然后，我们还从增殖、氧化应激、形态变化和细胞损伤等方面评估了这些效应。
镭-223 被 mPCa 细胞摄取并到达细胞核，在那里它随时间保留。照射降低了细胞存活和增殖，LNCaP 细胞（LD50=1.73mGy）比 PC3 细胞（LD50=4.20mGy）更敏感。照射后的细胞表现出通常与细胞凋亡相关的形态变化和 DNA 损伤的剂量依赖性增加。此外，细胞周期检查点的激活通过 ATM/CHK2 途径发生，该途径参与细胞周期阻滞和细胞死亡。
两种细胞系的细胞毒性和抗增殖作用表明，镭-223 可通过降低细胞存活和增殖以及增加 DNA 损伤来降低肿瘤细胞的侵袭性。在两种细胞系中观察到的相似结果表明，镭-223 可能有潜力作为治疗伴有淋巴结转移的 mCRPC 患者的治疗选择。DNA 损伤反应途径的激活使得这些检查点作为新的联合治疗靶点的重要性成为可能。
