Nitroimidazole-based inhibitors DTP338 and DTP348 are safe for zebrafish embryos and efficiently inhibit the activity of human CA IX in Xenopus oocytes

Abstract

Carbonic anhydrase (CA) IX is a hypoxia inducible enzyme that is highly expressed in solid tumours. Therefore, it has been considered as an anticancer target using specific chemical inhibitors. The nitroimidazoles DTP338 and DTP348 have been shown to inhibit CA IX in nanomolar range in vitro and reduce extracellular acidification in hypoxia, and impair tumour growth. We screened these compounds for toxicity using zebrafish embryos and measured their in vivo effects on human CA IX in Xenopus oocytes. In the toxicity screening, the LD₅₀ for both compounds was 3.5 mM. Neither compound showed apparent toxicity below 300 µM concentration. Above this concentration, both compounds altered the movement of zebrafish larvae. The IC₅₀ was 0.14 ± 0.02 µM for DTP338 and 19.26 ± 1.97 µM for DTP348, suggesting that these compounds efficiently inhibit CA IX in vivo. Our results suggest that these compounds can be developed as drugs for cancer therapy.

Keywords:

• Nitroimidazoles
• carbonic anhydrase IX
• zebrafish
• Xenopus oocytes
• in vivo inhibition

Acknowledgements

We thank Aulikki Lehmus and Marianne Kuuslahti for the histochemical analyses of the zebrafish samples. We also thank Leena Mäkinen and Hannaleena Piippo for the assistance with zebrafish embryos for the experiments.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The work was supported by grants from Sigrid Jusélius Foundation (SP, MP), Finnish Cultural Foundation (HB, AA, MH), Academy of Finland (SP), Orion-Farmos Foundation (MH) and Tampere Tuberculosis Foundation (SP, MH, and MP).