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Cancers 2019, 11(1), 110;

Alternating Electric Fields (TTFields) Activate Cav1.2 Channels in Human Glioblastoma Cells

Department of Radiation Oncology, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany
Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
German Cancer Consortium (DKTK) partnersite Tübingen, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
Author to whom correspondence should be addressed.
E.N. and L.Z. contributed equally to this work and, thus, share first-authorship.
Received: 25 October 2018 / Revised: 16 December 2018 / Accepted: 15 January 2019 / Published: 18 January 2019
(This article belongs to the Special Issue Ion Channels in Cancer)
Full-Text   |   PDF [4573 KB, uploaded 18 January 2019]   |  


Tumor treating fields (TTFields) represent a novel FDA-approved treatment modality for patients with newly diagnosed or recurrent glioblastoma multiforme. This therapy applies intermediate frequency alternating electric fields with low intensity to the tumor volume by the use of non-invasive transducer electrode arrays. Mechanistically, TTFields have been proposed to impair formation of the mitotic spindle apparatus and cytokinesis. In order to identify further potential molecular targets, here the effects of TTFields on Ca2+-signaling, ion channel activity in the plasma membrane, cell cycle, cell death, and clonogenic survival were tested in two human glioblastoma cell lines in vitro by fura-2 Ca2+ imaging, patch-clamp cell-attached recordings, flow cytometry and pre-plated colony formation assay. In addition, the expression of voltage-gated Ca2+ (Cav) channels was determined by real-time RT-PCR and their significance for the cellular TTFields response defined by knock-down and pharmacological blockade. As a result, TTFields stimulated in a cell line-dependent manner a Cav1.2-mediated Ca2+ entry, G1 or S phase cell cycle arrest, breakdown of the inner mitochondrial membrane potential and DNA degradation, and/or decline of clonogenic survival suggesting a tumoricidal action of TTFields. Moreover, inhibition of Cav1.2 by benidipine aggravated in one glioblastoma line the TTFields effects suggesting that Cav1.2-triggered signaling contributes to cellular TTFields stress response. In conclusion, the present study identified Cav1.2 channels as TTFields target in the plasma membrane and provides the rationale to combine TTFields therapy with Ca2+ antagonists that are already in clinical use. View Full-Text
Keywords: glioma; alternating electric field therapy; Ca2+ signaling; programmed cell death; clonogenicity; L-type Ca2+ channel; benidipine glioma; alternating electric field therapy; Ca2+ signaling; programmed cell death; clonogenicity; L-type Ca2+ channel; benidipine

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Neuhaus, E.; Zirjacks, L.; Ganser, K.; Klumpp, L.; Schüler, U.; Zips, D.; Eckert, F.; Huber, S.M. Alternating Electric Fields (TTFields) Activate Cav1.2 Channels in Human Glioblastoma Cells. Cancers 2019, 11, 110.

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