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Knockdown of the small conductance Ca 2+ ‐activated K + channels is potently cytotoxic in breast cancer cell lines
Author(s) -
Abdulkareem Zana Azeez,
Gee Julia MW,
Cox Charles D,
Wann Kenneth T
Publication year - 2016
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.13357
Subject(s) - gene knockdown , caspase 7 , cell culture , potassium channel , cytotoxic t cell , apoptosis , cell growth , chemistry , microbiology and biotechnology , biology , cancer research , caspase 3 , programmed cell death , in vitro , biochemistry , biophysics , genetics
Background and Purpose Small conductance calcium‐activated potassium (K Ca 2.x) channels have a widely accepted canonical function in regulating cellular excitability. In this study, we address a potential non‐canonical function of K Ca 2.x channels in breast cancer cell survival, using in vitro models. Experimental Approach The expression of all K Ca 2.x channel isoforms was initially probed using RT‐PCR, Western blotting and microarray analysis in five widely studied breast cancer cell lines. In order to assess the effect of pharmacological blockade and siRNA‐mediated knockdown of K Ca 2.x channels on these cell lines, we utilized MTS proliferation assays and also followed the corresponding expression of apoptotic markers. Key Results All of the breast cancer cell lines, regardless of their lineage or endocrine responsiveness, were highly sensitive to K Ca 2.x channel blockade. UCL1684 caused cytotoxicity, with LD 50 values in the low nanomolar range, in all cell lines. The role of K Ca 2.x channels was confirmed using pharmacological inhibition and siRNA‐mediated knockdown. This reduced cell viability and also reduced expression of Bcl‐2 but increased expression of active caspase‐7 and caspase‐9. Complementary to these results, a variety of cell lines can be protected from apoptosis induced by staurosporine using the K Ca 2.x channel activator CyPPA. Conclusions and Implications In addition to a well‐established role for K Ca 2.x channels in migration, blockade of these channels was potently cytotoxic in breast cancer cell lines, pointing to modulation of K Ca 2.x channels as a potential therapeutic approach to breast cancer.