Abstract B16: Potassium channel activators inhibit migration of breast cancer cells by hijacking the WNT signaling pathway

Abstract

Abstract Potassium ion channels are transmembrane associated proteins that play fundamental role in several biological processes including cell proliferation by controlling potassium ion flow across the membrane. Interestingly, the Kv11.1 potassium channel has been found expressed in a large variety of cancers of different histogenesis including breast cancers. However, very little is known about the role of this channels in cancer biology. We recently demonstrated that stimulation of Kv11.1 activity with the pharmacological Kv11.1 activators (e.g. NS1643) induces irreversible growth arrest in several breast cancer cell types, and this G1 cell cycle arrest was maintained after the chemical activator was removed. Kv11.1 activator-induced growth arrest was associated with increased expression of tumor suppressor including p21Waf and p16INK4A, reduced protein level of breast tumor markers such as cyclin E2, and augmented beta galactosidase activity. These outcomes are hallmarks of senescent cells that exist in an irreversible non-proliferative state. In the current work we have further studied the role of KV11.1 stimulation on migration of breast cancer cells. In the current study we report that activation of Kv11.1 by small molecule NS1643 inhibits migration of various cancer cells irrespective of their biomarker status. Using a wound healing and chamber migration assay we observed that NS1643 inhibits migration of triple negative (MDA-MB-231), Her2+ (SKBR3) and as well as ER+ (MCF7) cell lines. Following the molecular mechanisms of NS1643 dependent inhibition of migration, we observed that, the nuclear translocation of β-catenin and subsequently Wnt-3a mediated β-catenin/TCF promoter reporter activity was inhibited when treated with NS1643, suggesting that, activation of Kv11.1 with NS 1643 inhibited the Wnt3a/β-catenin pathway. Consistent with the β-catenin nuclear activity it was observed that phosphorylation of β-catenin (ser 552/656) was significantly decreased following treatment with NS1643. Interestingly however it was observed that the total β-cateninin levels were differentially regulated in breast cancer cell subtypes. We observed that β-catenin levels were increase in Her2+ and triple negative cell lines while decreased in ER+ cell lines following KV11.1 stimulation by NS 1643. Furthermore using immunoprecipitation and confocal microscopy we observed that, in E-cadherin expressing breast cancer cell lines, NS1643 was able confer a mesenchymal to epithelial transformation by promoting the sequestration of β-catenin and E-cadherin complex at the plasma membrane. These results indicate that, activation of Kv11.1 in breast cancer cell lines could be a novel therapeutic approach for inhibition of breast cancer cell migration. Note: This abstract was not presented at the conference. Citation Format: Gentile Saverio, Vidhya Rao, Mathew Perez-Neut. Potassium channel activators inhibit migration of breast cancer cells by hijacking the WNT signaling pathway. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B16.