Gossypol stimulates opening of a Ca 2+ - and Na + -permeable but Ni 2+ - and Co 2+ -impermeable pore in bEND.3 endothelial cells.

Gossypol, a polyphenolic dialdehyde toxin isolated from cotton seed, has anti-cancer properties and has recently shown some success in the treatment of glioma. Its effects on brain neurons and blood vessels are poorly understood. In this work we examined the effects of gossypol on cytosolic Ca ²⁺ concentration ([Ca ²⁺ ] _i ) of mouse brain bEND.3 endothelial cells. Cell viability tests revealed that after 3 hour and 18 hour exposures, 10 µmol/L gossypol caused 23% and 65% cell death, respectively; 3 µmol/L gossypol caused no and 21% cell death, respectively. [Ca ²⁺ ] _i was raised concentration-dependently by 1-10 µmol/L gossypol. We then explored the Ca ²⁺ signalling triggered by 3 µmol/L gossypol, which inflicted minimal toxicity: the Ca ²⁺ signal was composed largely of Ca ²⁺ influx and to a small extent, intracellular Ca ²⁺ release. Such Ca ²⁺ influx was much larger than store-operated Ca ²⁺ influx triggered by maximal Ca ²⁺ pool depletion. The Ca ²⁺ influx triggered by 3 and 10 µmol/L gossypol caused NO release and cell death, respectively. Gossypol also triggered influx of Mn ²⁺ and Na ⁺ , but not Ni ²⁺ and Co ²⁺ . Gossypol-triggered Ca ²⁺ signal was inhibited only by 14% and 37% by 100 µmol/L La ³⁺ and 10 µmol/L nimodipine, respectively; and not suppressed at all by 5 mmol/L Ni ²⁺ . Gossypol-triggered Ca ²⁺ signal was suppressed by 78% by 30 µmol/L ruthenium red, suggesting gossypol may act on TRPV channels. Our results suggest gossypol triggered opening of a non-selective cation pore, possibly a member of the TRPV family.
(© 2018 John Wiley & Sons Australia, Ltd.)