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Published on: September 19, 2014
High-Affinity NIR-Fluorescent Inhibitors for Tumor Imaging via Carbonic Anhydrase IX
Gediminas Žvinys1, Agne Petrosiute1, Audrius Zakšauskas1
1Department of Biothermodynamics and Drug Design, Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio 7, Vilnius LT-10257, Lithuania.
Abstract:
Tumor imaging and delivery of therapeutic agents may be achieved by designing high-affinity and high-selectivity compounds recognizing a tumor cell-expressing biomarker, such as carbonic anhydrase IX (CA IX). The CAIX, overexpressed in many hypoxic solid tumors, helps adjust to the energy requirements of the hypoxic environment, reduces intracellular acidification, and participates in the metastatic invasion of adjacent tissues. Here, we designed a series of sulfonamide compounds bearing CAIX-recognizing, high-affinity, and high-selectivity groups conjugated via a PEG linker to near-infrared (NIR) fluorescent probes used in the clinic for optically guided cancer surgery. We determined compound affinities for CAIX and other 11 catalytically active CA isozymes by the thermal shift assay and showed that the affinity Kd value of CAIX was in the subnanomolar range, hundred to thousand-fold higher than those of other CA isozymes. Similar affinities were also observed for CAIX expressed on the cancer cell surface in live HeLa cell cultures, as determined by the competition assay. The NIR-fluorescent compounds showed excellent properties in visualizing CAIX-positive tumors but not CAIX-negative knockout tumors in a nude mice xenograft model. These compounds would therefore be helpful in optically guided cancer surgery and could potentially be developed for anticancer treatment by radiotherapy.
Insights
Researchers developed novel near-infrared fluorescent probes that target carbonic anhydrase IX (CA IX), a biomarker overexpressed in hypoxic tumors. These probes enable precise tumor visualization for surgical guidance and hold potential for cancer therapy.
Area of Science:
- Biomedical Engineering
- Oncology
- Chemical Biology
Background:
- Carbonic anhydrase IX (CA IX) is a biomarker overexpressed in many hypoxic solid tumors.
- CA IX plays a role in tumor adaptation to hypoxia, intracellular pH regulation, and metastasis.
- Targeting CA IX is a promising strategy for tumor imaging and therapeutic agent delivery.
Purpose of the Study:
- To design and synthesize high-affinity, high-selectivity sulfonamide compounds targeting CA IX.
- To conjugate these compounds to near-infrared (NIR) fluorescent probes for optical imaging.
- To evaluate the efficacy of these probes in visualizing CA IX-expressing tumors.
Main Methods:
- Design and synthesis of sulfonamide compounds linked to NIR fluorescent probes via a PEG linker.
- Determination of compound affinity for CA IX and other carbonic anhydrase (CA) isozymes using thermal shift assays.
- Assessment of CA IX binding on live cancer cells using competition assays.
- In vivo tumor imaging in a nude mice xenograft model using NIR fluorescence.
Main Results:
- The designed compounds exhibited subnanomolar affinity for CA IX, with affinities 100-1000 fold higher than for other CA isozymes.
- High affinity for cell-surface CA IX was confirmed in live cancer cell cultures.
- NIR-fluorescent compounds successfully visualized CA IX-positive tumors but not CA IX-negative tumors in vivo.
Conclusions:
- The developed NIR-fluorescent probes demonstrate high affinity and selectivity for CA IX.
- These probes are effective for optically guided cancer surgery by visualizing CA IX-positive tumors.
- The compounds show potential for development into anticancer therapeutics, including radiotherapy enhancement.
