An SAR study of hydroxy-trifluoromethylpyrazolines as inhibitors of Orai1-mediated store operated Ca2+ entry in MDA-MB-231 breast cancer cells using a convenient Fluorescence Imaging Plate Reader assay

Bioorg Med Chem. 2018 Jul 23;26(12):3406-3413. doi: 10.1016/j.bmc.2018.05.012. Epub 2018 May 9.


The proteins Orai1 and STIM1 control store-operated Ca2+ entry (SOCE) into cells. SOCE is important for migration, invasion and metastasis of MDA-MB-231 human triple negative breast cancer (TNBC) cells and has been proposed as a target for cancer drug discovery. Two hit compounds from a medium throughput screen, displayed encouraging inhibition of SOCE in MDA-MB-231 cells, as measured by a Fluorescence Imaging Plate Reader (FLIPR) Ca2+ assay. Following NMR spectroscopic analysis of these hits and reassignment of their structures as 5-hydroxy-5-trifluoromethylpyrazolines, a series of analogues was prepared via thermal condensation reactions between substituted acylhydrazones and trifluoromethyl 1,3-dicarbonyl arenes. Structure-activity relationship (SAR) studies showed that small lipophilic substituents at the 2- and 3-positions of the RHS and 2-, 3- and 4-postions of the LHS terminal benzene rings improved activity, resulting in a novel class of potent and selective inhibitors of SOCE.

Keywords: Ca(2+) release-activated Ca(2+) (CRAC) channel; Hydroxy-trifluoromethylpyrazoline; Inhibitor; Orai1; Store-operated Ca(2+)entry (SOCE); Structure-activity relationship (SAR); Triple negative breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Calcium / metabolism
  • Calcium Channel Blockers / chemistry*
  • Calcium Channel Blockers / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Signaling / drug effects
  • Cell Line, Tumor
  • Female
  • Humans
  • ORAI1 Protein / antagonists & inhibitors*
  • ORAI1 Protein / metabolism
  • Protein Array Analysis
  • Pyrazoles / chemistry*
  • Pyrazoles / metabolism
  • Pyrazoles / pharmacology
  • Spectrometry, Fluorescence
  • Structure-Activity Relationship


  • Calcium Channel Blockers
  • ORAI1 Protein
  • ORAI1 protein, human
  • Pyrazoles
  • Calcium