**3.6. Calcium-activated potassium channels as pharmacological targets in breast cancer**

The hIKCa1 blockers, TRAM-34, and clotrimazole, or siRNA-hIKCa1 inhibit the prolactininduced proliferation of the MCF7 breast cancer cells [98].

Iberiotoxin inhibits large conductance of Ca2+-activated K<sup>+</sup> channels (BKCa) in three types of breast cancer cell lines (e.g., UACC893, SK-BR-3, and MDA-MB-231), eliciting cellular depolarization, attenuating the anchorage-independent growth [99]. Oppositely, HER-2/neuoverexpressing SK-BR-3 cells were insensitive to iberiotoxin [99].

#### **3.7. Calcium-activated chloride channels as pharmacological targets in breast cancer**

CaCCinh-A01, an inhibitor of calcium-activated chloride channels ANO1, diminishes breast cancer cell viability and colony formation [102]. Recent clinical studies showed that ANO1 is upregulated in breast cancer in comparison with fibroadenoma [103]. Moreover, patients with progesterone receptor-positive or HER2-negative breast cancer, or breast cancer patients treated with tamoxifen, have an upregulation of ANO1, which can be considered as a predictive factor for longer overall survival [103].
