Tumour Treating Fields Effect on Cell Viability is Determined by Cell Orientation and Field Direction

Engineering approaches for the treatment of cancer have gained significant interest in recent years. For brain tumours, these include the alternating current (AC) electric field therapy known as Tumour Treating Fields (TTFs)[1][2]. TTFs are believed to disrupt the mitotic spindle of tubulin during the formation of microtubules in cancerous cells. By inducing an AC electric field at specific frequencies, dipolar molecules in the cell polarise, ultimately leading to early metaphase exit and cellular death. During cytokinesis, cells dividing parallel to the direction of the electric fields experience large dielectrophoretic force at the division furrow thought to cause macromolecule movement and further cellular breakdown. There is sufficient evidence that electric fields can be used to align and pattern cells, but to date only computational models exploring TTFs and their dielectrophoretic effects have been reported with no clear experimental or <i>in vitro/vivo</i> validation.<br/>Here, we show by using photolithographic patterning and protein attaching arrangements, that adherent glioblastoma stem-like cells can be organised into parallel, perpendicular and diagonal patterns with respect to the applied electric field. The indication of whether or not a cell can commit to cell division is shown by using live cell FUCCI (fluorescence ubiquitination cell cycle indicator) transduction where cells fluoresce red in G1 and green in S/G2/M cell cycle phases. This provides visual indication of the directionality effect of TTFs in terms of cell cycle disruption. In tandem, actin filament staining confirmed by Fast Fourier transforms represent the angle at which the effect of TTFs is greatest and weakest. This work not only provides insights into the mechanism of action of TTFs, but also design considerations for electrode placement. Thus, these indications offer insights for greater therapeutic benefit and recruitment of TTFs in practice as well as improved patient outcomes for treating Glioblastoma.<br/>References:<br/>[1] doi.org/10.1158/0008-5472.can-04-0083<br/>[2] doi.org/10.1002/advs.202100978