Inhibition of cancerous properties of triple-negative MDA-MB-436 cells by targeting the K+ voltage-dependent Kv2.1 channel

: We have investigated the involvement of K+ channels in generating the membrane current in MDA-MB-436 cells, a model of triple-negative breast cancer (TNBC). The membrane current is strongly influenced by the opening of voltage-dependent channels insensitive to the nonspecific K+ channel inhibitor 4-aminopyridine (4-AP). Using the cell patch clamp technique, we observed a significant decrease in membrane current after exposure to the generic K+ channel inhibitor tetraethylammonium chloride (TEA-Cl), indicating that K+ ions contribute to the overall membrane current through K+ channels that are insensitive to 4-AP but TEA-Cl-sensitive. RNA-sequencing analysis identified the Big Potassium (BK or Maxi-K or KCa1.1, encoded by KCNMA1) and the Kv2.1 (encoded by KCNB1) channels as putative candidates, both of which are involved in cancer cell proliferation and migration. Iberiotoxin, a specific inhibitor of BK channels, did not affect the total membrane current, just as CdCl₂ did, a potent inhibitor of Ca2⁺ channels involved in BK activation. Using selective inhibitors, stromatoxin and drofenine, we demonstrated that the Kv2.1 channel contributes to the membrane current in MDA-MB-436 cells. Furthermore, drofenine inhibited cell migration as measured by the xCELLigence Real-Time Cell Analyzer System and induced apoptosis. Single-cell analysis revealed that the Kv2.1 channel is expressed in both normal and cancerous tissues, with significant upregulation in brain metastases. This raises the possibility that Kv2.1 could be explored as a potential therapeutic target for controlling advanced stages of the neoplasia.