Plasma membrane-associated
adenosine triphosphatase (
ATPase) samples partially purified from the
tumor dissections of 15
gastric cancer patients were examined for sensitivity to the synthetic
lignan,
2,3-dibenzylbutane-1,4-diol (
hattalin), and
ouabain in the presence of Mg2+, Na+, and K+.
Hattalin was the strongest
Na+, K(+)-ATPase inhibitor among the
lignans previously examined. The
enzyme from normal gastric tissue of the same patient was used as control. The specific activity of
ATPase from
cancer tissue (C-
ATPase) was inhibited by more than 50% by 2.0 mM
hattalin, whereas only 33.1% of the specific activity of
ATPase from normal gastric mucosa (N-
ATPase) was inhibited by 2.0 mM
hattalin. There was statistical significance of
lignan sensitivity between C- and N-
ATPase (p less than 0.02).
Ouabain also inhibited C-
ATPase in preference to N-
ATPase, though not significantly.
Hattalin inhibited both C- and N-
ATPase more strongly than did
ouabain (p less than 0.05). Moreover, the
lignan inhibited both C- and N-
ATPase in the absence of Na+ and K+. From these data, it is evident that the sensitivity of plasma membrane-associated to
lignan increased by gastric canceration. The target
ATPase of
hattalin is likely to be one other than
sodium- and
potassium-dependent,
ouabain-sensitive
ATPase.