Differential effects of cyanohydroxybutene and selenium on normal and neoplastic canine mammary cells in vitro

The in vitro responses of canine mammary tumor (CMT-13) cells and normal canine mammary (NCM) cells to 1-cyano-2-hydroxy-3-butene (CHB), a naturally occurring nitrile in cruciferous plants, and selenium (Se) were investigated. CHB at 10 and 20 mM inhibited growth and viability of CMT-13 and NCM cells, respectively. This differential sensitivity was associated with a decreased ability of CMT-13 cells to increase intracellular glutathione (GSH) in comparison to NCM cells. Exposure of both cell types to 3.2 microM Se as sodium selenite alone had no effects, but addition of 3.2 microM Se 24 h after exposure to non-toxic doses of CHB resulted in a substantial decrease in growth of CMT cells, while NCM cells remained unaffected. The synergy noted between CHB and Se in inhibiting growth and viability of neoplastic mammary cells at levels not toxic to normal mammary cells is promising initial evidence that CHB could have a role in chemoprotection or chemotherapy.