The three-tails approach as a new strategy to improve selectivity of action of sulphonamide inhibitors against tumour-associated carbonic anhydrase IX and XII

J Enzyme Inhib Med Chem. 2022 Dec;37(1):930-939. doi: 10.1080/14756366.2022.2053526.


Human (h) carbonic anhydrase (CAs, EC isoforms IX and XII were recently confirmed as anticancer targets against solid hypoxic tumours. The "three-tails approach" has been proposed as an extension of the forerunner "tail" and "dual-tail approach" to fully exploit the amino acid differences at the medium/outer active site rims among different hCAs and to obtain more isoform-selective inhibitors. Many three-tailed inhibitors (TTIs) showed higher selectivity against the tumour-associated isoforms hCA IX and XII with respect to the off-targets hCA I and II. X-ray crystallography studies were performed to investigate the binding mode of four TTIs in complex with a hCA IX mimic. The ability of the most potent and selective TTIs to reduce in vitro the viability of colon cancer (HT29), prostate adenocarcinoma (PC3), and breast cancer (ZR75-1) cell lines was evaluated in normoxic (21% O2) and hypoxic (3% O2) conditions demonstrating relevant anti-proliferative effects.

Keywords: Tail approach; X-ray crystallography; carbonic anhydrase; hypoxic tumour; inhibitor.

MeSH terms

  • Antigens, Neoplasm / metabolism
  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology*
  • Carbonic Anhydrase IX / antagonists & inhibitors*
  • Carbonic Anhydrase IX / metabolism
  • Carbonic Anhydrase Inhibitors / chemical synthesis
  • Carbonic Anhydrase Inhibitors / chemistry
  • Carbonic Anhydrase Inhibitors / pharmacology*
  • Carbonic Anhydrases / metabolism*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Humans
  • Molecular Structure
  • Structure-Activity Relationship
  • Sulfonamides / chemical synthesis
  • Sulfonamides / chemistry
  • Sulfonamides / pharmacology*


  • Antigens, Neoplasm
  • Antineoplastic Agents
  • Carbonic Anhydrase Inhibitors
  • Sulfonamides
  • CA9 protein, human
  • Carbonic Anhydrase IX
  • Carbonic Anhydrases
  • carbonic anhydrase XII

Grants and funding

This project was funded by the Researchers Supporting Project number [RSP-2021/405], King Saud University, Riyadh, Saudi Arabia (SMO) and by the Italian Ministry for University and Research (Ministero dell'Istruzione, dell'Università e della Ricerca [MIUR]), grant PRIN: prot. 2017XYBP2R (CTS).