Conclusions
As the main potential target of CS-6, ATP1A3 activation critically depends on the hydrogen bonding of Thr794 with CS-6. The combination of CS-6 and TMZ could significantly reduce the therapeutic doses and promote the anti-cancer efficacy of CS-6/TMZ monotherapy.
Methods
Target fishing experiment, Western blotting, PCR, confocal immunofluorescence and molecular cloning techniques were performed to search for possible downstream signalling pathways. In addition, GBM xenografts were used to further determine the potential molecular mechanisms of the synergistic effects of CS-6 and TMZ in vivo.
Results
Mechanistic research revealed a negative feedback loop between ATP1A3 and AQP4 through which CS-6 inhibited GBM growth and mediated the synergistic treatment effect of CS-6 and TMZ. In addition, by mutating potential amino acid residues of ATP1A3, which were predicted by modelling and docking to interact with CS-6, we demonstrated that abrogating hydrogen bonding of the amino acid Thr794 interferes with the activation of ATP1A3 by CS-6 and that the Thr794Ala mutation directly affects the synergistic treatment efficacy of CS-6 and TMZ. Conclusions: As the main potential target of CS-6, ATP1A3 activation critically depends on the hydrogen bonding of Thr794 with CS-6. The combination of CS-6 and TMZ could significantly reduce the therapeutic doses and promote the anti-cancer efficacy of CS-6/TMZ monotherapy.