Colorectal cancer (CRC) and non-small cell lung cancer (NSCLC) continue to be major contributors to cancer mortality worldwide. While targeted therapies like EGFR inhibitors have helped some patients, they often stop working over time because cancer cells become resistant. In many cases, the side effects also limit how much of the drug can be safely used.

In a recent study, researchers identified vitexicarpin, a flavonoid isolated from Vitex trifolia, as a potent and selective inhibitor of the calcium-activated chloride channel ANO1 (also known as TMEM16A), which plays a critical role in tumor progression, migration, and drug resistance.

The team used a YFP-based high-throughput screening assay to identify natural compounds that block ANO1-mediated chloride conductance. Vitexicarpin emerged as a top candidate, effectively inhibiting ANO1 function without affecting CFTR channel activity or ATP-induced intracellular calcium release, indicating strong target selectivity.

The study demonstrated that vitexicarpin:

• Inhibits ANO1 channel function in epithelial models (short-circuit current assays)
• Reduces ANO1 protein levels in CRC (HT29) and NSCLC (PC9) cells, without affecting ANO1 mRNA, suggesting proteasomal degradation
• Induces apoptosis, evidenced by increased caspase-3 activity, PARP-1 cleavage, and accumulation of sub-G1 population
• Suppresses cell viability in HT29 and gefitinib-resistant PC9-GR cells
• Exhibits minimal hepatotoxicity (HepG2 assay)
• Has low cardiotoxic potential, as measured by hERG channel inhibition

To evaluate cardiotoxicity, the team used the Patchliner system to measure hERG tail currents in HEK293 cells.

• Vitexicarpin showed low hERG inhibition, with an IC₅₀ of 35.4 µM
• In contrast, 10 µM quinidine completely blocked hERG currents

This result supports a low risk of QT prolongation, a common concern in preclinical safety pharmacology

Molecular insights and resistance relevance

Molecular docking and MD simulations revealed that vitexicarpin binds stably to the known ANO1 inhibitor site, forming key interactions with Arg515, Glu633, and Val599, residues previously implicated in channel function. Binding stability was further supported by low RMSD values across simulations.

Importantly, the study also addressed EGFR-TKI resistance, a major hurdle in NSCLC treatment. Vitexicarpin retained its anticancer activity in gefitinib-resistant PC9-GR cells, reducing viability with an IC₅₀ of ~1 µM, compared to an ~987-fold higher IC₅₀ for gefitinib in the same model.

Vitexicarpin stands out among ANO1 inhibitors for its dual mechanism: channel blockade and protein downregulation, along with selectivity and safety. This combination positions it as both a pharmacological probe for ANO1 function and a potential lead compound for CRC and NSCLC therapy, including drug-resistant cases.

—

📖 Read the full article: Vitexicarpin suppresses colorectal and non-small cell lung cancer via selective inhibition of Anoctamin 1

Working on ion channels in cancer? Learn about our automated patch clamp solutions Automated patch clamp – Nanion Technologies