Harnessing Nitric Oxide-Donating Benzofuroxans for Targeted Inhibition of Carbonic Anhydrase IX in Cancer

We
describe here the design and antitumor evaluation of benzofuroxan-based
nitric oxide (NO)-donor hybrid derivatives targeting human carbonic
anhydrases (hCAs) IX and XII. The most effective compounds, 27 and 28, demonstrated potent dual action, exhibiting
low nanomolar inhibition constants against hCA IX and significant
NO release. Notably, compound 27 showed significant antiproliferative
effects against various cancer cell lines, particularly renal carcinoma
A-498 cells. In these cells, it significantly reduced the expression
of CA IX and iron-regulatory proteins, inducing apoptosis via mitochondrial
caspase activity and ferroptosis pathways, as evidenced by increases
in ROS, nitrite, and down-regulated expression of ferritin-encoding
genes. In three-dimensional tumor models, compound 27 effectively reduced spheroid size and viability. In vivo toxicity studies in mice indicated that the compounds were well-tolerated,
with no significant alterations in kidney function. These findings
underscore the potential of benzofuroxan-based CA inhibitors for further
preclinical evaluations as therapeutic agents targeting renal cell
carcinoma.