diba-1 and Neoplasms

Topics: Antigens, Neoplasm; Antineoplastic Agents; Binding Sites; Biomarkers, Tumor; Carbonic Anhydrase Inhibitors; Carbonic Anhydrase IX; Carbonic Anhydrases; Cell Hypoxia; Humans; Isoenzymes; Neoplasms

2-Substituted-5-nitro-benzenesulfonamides incorporating a large variety of secondary/tertiary amines were explored as inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), with the aim of designing bioreductive inhibitors targeting the hypoxia overexpressed, tumor-associated isozymes. The compounds were ineffective inhibitors of the cytosolic isoform I, showed a better inhibition of the physiologically relevant CA II (KIs of 8.8-4975 nM), and strongly inhibited the tumor-associated CA IX and XII (KIs of 5.4-653 nM). Some of these compounds showed excellent selectivity ratios for the inhibition of the tumor-associated isozymes over the cytosolic ones (in the range of 10-1395). The X-ray crystal structure of the adduct of hCA II with the lead molecule 2-chloro-5-nitro-benzenesulfonamide as well as molecular modeling studies for interaction with hCA IX afforded a better understanding of factors governing the discrimination of the two isoforms for this type of bioreductive compound targeting specifically hypoxic tumors.

Topics: Amino Acid Sequence; Antigens, Neoplasm; Carbonic Anhydrase I; Carbonic Anhydrase II; Carbonic Anhydrase Inhibitors; Carbonic Anhydrase IX; Carbonic Anhydrases; Conserved Sequence; Crystallography, X-Ray; Humans; Isoenzymes; Models, Molecular; Molecular Sequence Data; Neoplasms; Nitro Compounds; Structure-Activity Relationship; Sulfonamides

An approach for designing bioreductive, hypoxia-activatable carbonic anhydrase (CA, EC 4.2.1.1) inhibitors targeting the tumor-associated isoforms is reported. Sulfonamides incorporating 3,3'-dithiodipropionamide/2,2'-dithiodibenzamido moieties were prepared and reduced enzymatically/chemically in conditions present in hypoxic tumors, leading to thiols. The X-ray crystal structure of the most promising compound, 4-(2-mercaptophenylcarboxamido)benzenesulfonamide, which as disulfide showed a K(I) against hCA IX of 653 nM (in reduced form of 9.1 nM), in adduct with hCA II showed the inhibitor making favorable interactions with Gln92, Val121, Phe131, Leu198, Thr199, Thr200, Pro201, and Pro202, whereas the sulfamoyl moiety was coordinated to the Zn2+ ion. The same interactions were preserved in the adduct with hCA IX, but in addition, a hydrogen bond between the SH moiety of the inhibitor and the amide nitrogen of Gln67 was evidenced, which may explain the almost 2 times more effective inhibition of the tumor-associated isozyme over the cytosolic isoform.

Topics: Antigens, Neoplasm; Carbonic Anhydrase II; Carbonic Anhydrase Inhibitors; Carbonic Anhydrase IX; Carbonic Anhydrases; Crystallography, X-Ray; Disulfides; Enzyme Activation; Humans; Hydrogen Bonding; Hypoxia; Isoenzymes; Models, Molecular; Molecular Structure; Neoplasms; Prodrugs; Protein Binding; Structure-Activity Relationship; Sulfhydryl Compounds; Sulfonamides