Effect of Three Calmodulin Antagonists on Subpopulations of CD44/CD24 Immunophenotypes in Breast Cancer Cell Lines

Purpose: To determine the effect of three calmodulin antagonists (A-7, W-7 and W-13) on the subpopulations of CD44/CD24 immunophenotypes in MDA-MB-231 and MDA-MB-468 breast cancer cell lines.
Methods: Flow cytometry analysis was used to determine the proportion of the various subpopulations of the immunophenotypes, viz, CD44+CD24−, CD44−CD24+ and CD44+CD24+, when MDA-MB-231 and MDA-MB-468 cells were subjected to calmodulin antagonists. The effect of W-13 on the invasion properties of MDA-MB-231 and MDA-MB-468 was investigated using Matrigel invasion assay.
Results: A-7, W-7 and W-13 caused alterations in the subpopulation of CD44+CD24− in MDA-MB-231 cells. The most potent antagonist was W-13 as it reduced the proportion of tumorigenic CD44+CD24− to 0.64 ± 0.05 at a concentration of 80 μM. In contrast, the subpopulation of MDA-MB-468 cells, which had a low fraction of CD44+CD24−, was not altered when administered with W-7 but showed variations when incubated with W-13. Specifically, when the concentration of W-13 increased from 20 – 100 μM, the proportion of CD44+CD24+ was reduced from 92.93 ± 3.2 to 60.96 ± 2.4. The effect of W-13 on the subpopulations of CD44+CD24− and CD44+CD24+ in MDA-MB-231 and MDA-MB-468, respectively, reduced the invasion properties of the cells.
Conclusion: The calmodulin antagonist, W-13, has a significant antitumor effect on MDA-MB-231 and MDA-MB-468 breast cancer cells.

Keywords
Calmodulin antagonists; Flow cytometry; Invasion assay; Immunophenotypes