Abstract
AIMS
Develop and validate a comprehensive understanding of CLIC1 and its prognostic significance, coupled with a functional analysis in pHGG cells.
To develop electrical and pharmacological methods of manipulating CLIC1 for combination with TTFields
METHOD
Chloride Intracellular Channel (CLIC) channel expression patterns were identified via RNA sequencing of in- house patient tissues. siRNA depletion of CLIC1 and CLIC4 was assessed using functional assays, alone and in combination with TTFields and or CLIC inhibitor. Whole transcriptome gene expression analysis (Human Clairom™ Array) of pGBM cells treated with TTFields was carried out. Whole cell and cell attached patch clamp protocols were used to assess ion channel activity in pHGG.
RESULTS
CLIC1 deficiency was associated with increased overall survival(p=<0.003). siRNA depletion propagates a re- duction in the proliferation, migration and invasion of pHGG cells, associated with cell cycle arrest. CLIC1 deficiency exacerbated the effect of TTFields, reducing clonogenic and proliferative capabilities. Combination of metformin and TTFields increased the sensitivity of cells to TTFields. Whole transcriptome gene expression analysis found that cells treated with TTFields exhibited a down-regulation in CLIC1 compared to untreated cells, with tolerance to long-term TTFields treatment being associated with recovery of CLIC1 expression.
CONCLUSIONS
These data provide rationale that genetic, electrical, and pharmacological manipulation of CLIC1 can reduce the capacity of childhood brain tumours to proliferate and invade. TTFields treatment results in a dysregulation of CLIC channel expression and function, and combination with CLIC inhibitions demonstrates a synergistic effect. CLIC channels may be a suitable target for combination therapy to enhance the treatment effcacy of TTFields.