Hypoxia-Targeting Carbonic Anhydrase IX Inhibitors by a New Series of Nitroimidazole-Sulfonamides/Sulfamides/Sulfamates

Abstract

A series of nitroimidazoles incorporating sulfonamide/sulfamide/sulfamate moieties were designed and synthesized as radio/chemosensitizing agent targeting the tumor-associated carbonic anhydrase (CA) isoforms IX and XII. Most of the new compounds were nanomolar inhibitors of these isoforms. Crystallographic studies on the complex of hCA II with the lead sulfamide derivative of this series clarified the binding mode of this type of inhibitors in the enzyme active site cavity. Some of the best nitroimidazole CA IX inhibitors showed significant activity in vitro by reducing hypoxia-induced extracellular acidosis in HT-29 and HeLa cell lines. In vivo testing of the lead molecule in the sulfamide series, in cotreatment with doxorubicin, demonstrated a chemosensitization of CA IX containing tumors. Such CA inhibitors, specifically targeting the tumor-associated isoforms, are candidates for novel treatment strategies against hypoxic tumors overexpressing extracellular CA isozymes.

Insights into the binding mode of sulphamates and sulphamides to hCA II: crystallographic studies and binding free energy calculations

“…To understand if the different position assumed by N2 and O3 atoms in the enzyme active site was associated to a peculiarity of the two complexes under investigation, or to a more general behaviour of sulphamate and sulphamide derivatives, a comparative analysis of all hCA II/sulphamate and hCA II/sulphamide structures available in the PDB was undertaken 25,26,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][67][68][69][70][71] . Surprisingly, the analysis of all these structures revealed that, independently of the nature of the moiety attached to the ZBG, the distance between the Thr200OG1 atom and the sulphamide nitrogen N2 in hCA II/sulphamide complexes was generally shorter than the corresponding distance between the sulphamate oxygen O3 and the same enzyme atom in hCA II/sulphamate complexes (see Tables 3 and 4).…”

“…As an example, compound JNJ-26990990 (2) (see Figure 1), which presents excellent anticonvulsant activity and can be potentially used in the treatment of multiple forms of epilepsy, is also a nanomolar inhibitor of several CA isoforms 24,25 . We recently reported the synthesis of a series of sulphonamide/sulphamide/sulphamate derivatives incorporating nitroimidazole moieties 26 . Inhibition studies against isoforms I, II, IX, and XII showed that these compounds, in particular, the sulphamate/ sulphamide derivatives 3 and 4 ( Figure 1), are good CAIs, with K I values in the nanomolar range.…”

“…Inhibition studies against isoforms I, II, IX, and XII showed that these compounds, in particular, the sulphamate/ sulphamide derivatives 3 and 4 ( Figure 1), are good CAIs, with K I values in the nanomolar range. Moreover, compound 4 was demonstrated to inhibit in vitro the hypoxia-induced extracellular acidosis in two cell lines overexpressing CA IX and to enhance in vivo, in co-treatment with doxorubicin, sensitisation towards radiotherapy and chemotherapy of CA IX containing tumours 26 . The X-ray crystal structure of the hCA II/4 adduct was also reported, highlighting the principal interactions responsible for the binding of the inhibitor to the enzyme active site 26 .…”

“…Moreover, compound 4 was demonstrated to inhibit in vitro the hypoxia-induced extracellular acidosis in two cell lines overexpressing CA IX and to enhance in vivo, in co-treatment with doxorubicin, sensitisation towards radiotherapy and chemotherapy of CA IX containing tumours 26 . The X-ray crystal structure of the hCA II/4 adduct was also reported, highlighting the principal interactions responsible for the binding of the inhibitor to the enzyme active site 26 . Within a research project aimed at understanding at the atomic level, the inhibition properties of sulphamate/sulphamide CAIs, here we report the X-ray crystal structure of the hCA II/3 adduct and compare it with the previously obtained hCA II/4 structure.…”

Trimeric Radiofluorinated Sulfonamide Derivatives to Achieve In Vivo Selectivity for Carbonic Anhydrase IX–Targeted PET Imaging

“…With the exception of the testes, stomach, kidney, and bone, uptake in nontarget tissues was higher for 18 F-AmBF 3 -(AEBS) 3 . On the basis of this observation, it appears that image contrast may be improved by selecting more hydrophilic CA-IX-targeting pharmacophores (38). Because 18 F-AmBF 3 -(ABS) 3 yielded the most promising results of the evaluated tracers, additional biodistribution studies were performed at 2 h after injection to determine whether tumor uptake or contrast would improve over time.…”