Batimastat, a potent matrix mealloproteinase inhibitor, exhibits an unexpected mode of binding.

Matrix metalloproteinase enzymes have been implicated in degenerative processes like tumor cell invasion, metastasis, and arthritis. Specific metalloproteinase inhibitors have been used to block tumor cell proliferation. We have examined the interaction of batimastat (BB-94) with a metalloproteinase [atrolysin C (Ht-d), EC 3.4.24.42] active site at 2.0-angstroms resolution (R = 16.8%). The title structure exhibits an unexpected binding geometry, with the thiophene ring deeply inserted into the primary specificity site. This unprecedented binding geometry dramatizes the significance of the cavernous primary specificity site, pointing the way for the design of a new generation of potential antitumor drugs.

The mode of action of aspirin-like drugs: effect on inducible nitric oxide synthase.

Nitric oxide synthesized by inducible nitric oxide synthase (iNOS) has been implicated as a mediator of inflammation in rheumatic and autoimmune diseases. We report that exposure of lipopolysaccharide-stimulated murine macrophages to therapeutic concentrations of aspirin (IC50 = 3 mM) and hydrocortisone (IC50 = 5 microM) inhibited the expression of iNOS and production of nitrite. In contrast, sodium salicylate (1-3 mM), indomethacin (5-20 microM), and acetaminophen (60-120 microM) had no significant effect on the production of nitrite at pharmacological concentrations. At suprapharmacological concentrations, sodium salicylate (IC50 = 20 mM) significantly inhibited nitrite production. Immunoblot analysis of iNOS expression in the presence of aspirin showed inhibition of iNOS expression (IC50 = 3 mM). Sodium salicylate variably inhibited iNOS expression (0-35%), whereas indomethacin had no effect. Furthermore, there was no significant effect of these nonsteroidal anti-inflammatory drugs on iNOS mRNA expression at pharmacological concentrations. The effect of aspirin was not due to inhibition of cyclooxygenase 2 because both aspirin and indomethacin inhibited prostaglandin E2 synthesis by > 75%. Aspirin and N-acetylimidazole (an effective acetylating agent), but not sodium salicylate or indomethacin, also directly interfered with the catalytic activity of iNOS in cell-free extracts. These studies indicate that the inhibition of iNOS expression and function represents another mechanism of action for aspirin, if not for all aspirin-like drugs. The effects are exerted at the level of translational/posttranslational modification and directly on the catalytic activity of iNOS.