title: Knockdown of the small conductance Ca(2+) -activated K(+) channels is potently cytotoxic in breast cancer cell lines.
abstract: OBJECTIVE
  Small conductance calcium-activated potassium (KCa 2.x) channels have a widely accepted canonical function in regulating cellular excitability. In this study, we address a potential non-canonical function of KCa 2.x channels in breast cancer cell survival, using in vitro models.
  
  
  METHODS
  The expression of all KCa 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 KCa 2.x channels on these cell lines, we utilized MTS proliferation assays and also followed the corresponding expression of apoptotic markers.
  
  
  RESULTS
  All of the breast cancer cell lines, regardless of their lineage or endocrine responsiveness, were highly sensitive to KCa 2.x channel blockade. UCL1684 caused cytotoxicity, with LD50 values in the low nanomolar range, in all cell lines. The role of KCa 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 KCa 2.x channel activator CyPPA.
  
  
  CONCLUSIONS
  In addition to a well-established role for KCa 2.x channels in migration, blockade of these channels was potently cytotoxic in breast cancer cell lines, pointing to modulation of KCa 2.x channels as a potential therapeutic approach to breast cancer.
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, CF10 3NB, UK.
authors.forename: Zana Azeez
authors.initials: ZA
authors.lastname: Abdulkareem
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, CF10 3NB, UK.
authors.forename: Julia Mw
authors.initials: JM
authors.lastname: Gee
authors.affiliation: Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Cox
authors.affiliation: School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, CF10 3NB, UK.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Wann
mesh_terms: D000473:Alkanes / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D055785:Gene Knockdown Techniques; D006801:Humans; D007928:Lethal Dose 50; D020033:Protein Isoforms / Q000096:biosynthesis / Q000172:deficiency; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D011806:Quinolinium Compounds / Q000633:toxicity; D034741:RNA, Small Interfering / Q000494:pharmacology; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000096:biosynthesis / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D019311:Staurosporine / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: C110349:6,10-diaza-3(1,3),8(1,4)dibenzena-1,5(1,4)diquinolinacyclodecaphane; D000473:Alkanes; D051017:Apoptosis Regulatory Proteins; D020033:Protein Isoforms; D011720:Pyrazoles; D011743:Pyrimidines; D011806:Quinolinium Compounds; D034741:RNA, Small Interfering; D051640:Small-Conductance Calcium-Activated Potassium Channels; C552889:cyclohexyl-(2-(3,5-dimethylpyrazol-1-yl)-6-methylpyrimidin-4-yl)amine; D019311:Staurosporine