Jobson Isobel, Vo Nguyen T N, Kujawinski Edward, Denning Chris, Stolnik Snow, Chauhan Veeren M, Rawson Frankie
School of Pharmacy, Biodiscovery Institute & Boots Science Building, University of Nottingham, Nottingham, NG7 2RD, UK.
Division of Cancer & Stem Cells, Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK.
Bioelectron Med. 2025 Jan 30;11(1):2. doi: 10.1186/s42234-024-00164-3.
In glioblastoma (GBM) therapy research, tumour treating fields by the company Novocure™, have shown promise for increasing patient overall survival. When used with the chemotherapeutic agent temozolomide, they extend median survival by five months. However, there is a space to design alternative systems that will be amenable for wider use in current research. Therefore, we sought to establish a custom-built alternating electric field device to investigate the effect of electrode design on the responsiveness of cancer cells to this therapy.
A 96-well microtiter plate modified with an electrode array was fabricated to investigate its application as an in vitro alternating electric field device. This was initially performed with patient-derived GCE 31 and GIN 31 cell lines found in the core and invasive margin of the GBM tumour, respectively. We sought to establish the effect of the application of low-intensity (3 V/ cm) electric fields with an application duration of 4-48 h, using intermediate frequency (300 kHz) alternating currents (AC). To demonstrate that electric fields were entering the cell, GCE 31 and GIN 31 cells were treated with the inorganic, non-conductive zinc oxide (ZnO) nanoparticles (NP), previously demonstrated to enhance the efficacy of TTFs. After a 4-h exposure to NP, cells were then exposed to alternating electric fields or currents and their metabolic activity was assessed. To better understand how the position and morphology of cells can affect cell therapy responsiveness to alternating electric fields or currents, GBM results were compared to those from the semi-adherent brain tumour cell line, D425.
Contrary to previous findings, there was no significant difference between the GIN 31 and GCE 31 cells exposed to alternating electric fields or currents treated with or without NP compared to cells untreated and unstimulated. D425 cells exposed to alternating electric fields exhibited a pronounced metabolic increase (1.8-fold), while those exposed to alternating electric currents with or without ZnO had a reduced metabolism relative to the untreated control.
The initial hypothesis for the lack of effect of electrical stimulation on the adherent cells was that, due to only a single pair of electrodes being used, the proportion of cells that were in the correct orientation for electric field effects was limited. However, the dramatic shift in cell behaviour of the semi-adherent cells shows that cell morphology plays an important role in the responsiveness of cancer cells to AC electric fields. This study highlights the lack of understanding of the complex mechanisms by which electric fields exert effects on cancer cells. We propose that, for the therapy to be enhanced for patients, research should first focus on the underlying mechanisms of action, specifically on how individual cancer cell types respond to this therapy.
在胶质母细胞瘤（GBM）治疗研究中，Novocure™公司的肿瘤治疗电场已显示出提高患者总生存期的前景。与化疗药物替莫唑胺联合使用时，可将中位生存期延长五个月。然而，仍有空间设计可供当前研究更广泛应用的替代系统。因此，我们试图建立一种定制的交变电场装置，以研究电极设计对癌细胞对该疗法反应性的影响。
制作了一个用电极阵列修饰的96孔微量滴定板，以研究其作为体外交变电场装置的应用。最初使用分别在GBM肿瘤核心和侵袭边缘发现的患者来源的GCE 31和GIN 31细胞系进行实验。我们试图确定施加低强度（3V/cm）电场、持续时间为4 - 48小时、使用中频（300kHz）交流电（AC）的效果。为了证明电场进入细胞，用无机、非导电的氧化锌（ZnO）纳米颗粒（NP）处理GCE 31和GIN 31细胞，此前已证明该纳米颗粒可增强肿瘤治疗电场的疗效。在NP处理4小时后，然后将细胞暴露于交变电场或电流中，并评估其代谢活性。为了更好地理解细胞的位置和形态如何影响细胞疗法对交变电场或电流的反应性，将GBM的结果与半贴壁脑肿瘤细胞系D425的结果进行比较。
与之前的研究结果相反，与未处理和未刺激的细胞相比，暴露于交变电场或电流且用或不用NP处理的GIN 31和GCE 31细胞之间没有显著差异。暴露于交变电场的D425细胞代谢明显增加（1.8倍），而暴露于有或没有ZnO的交变电流的细胞相对于未处理的对照代谢降低。
关于电刺激对贴壁细胞无效的最初假设是，由于仅使用了一对电极，处于电场效应正确方向的细胞比例有限。然而，半贴壁细胞的细胞行为的显著变化表明，细胞形态在癌细胞对交流电场的反应性中起重要作用。本研究突出了对电场作用于癌细胞的复杂机制缺乏了解。我们建议，为了增强对患者的治疗效果，研究应首先关注其潜在作用机制，特别是个体癌细胞类型对该疗法的反应方式。
