Disruption of the ER-α36-EGFR/HER2 positive regulatory loops sensitizes ER-positive breast cancer stem/progenitor cells to TAM.

<p>A. Tumorsphere formation assay was used to assess the effects of TAM alone or together with Lapatinib (LAP) or Broussoflavonol B (BB) on ER-positive breast cancer stem/progenitor cells derived from parental MCF7 (MCF7/P) and tamoxifen resistant MCF7 cells (MCF7/TAM). The representative results are shown. B. The numbers of tumorspheres formed by MCF7/P and MCF7/TAM cells in the presence or absence of LAP and BB for 1^st and 2^nd generations. C. The number of cells from dissociated tumorspheres formed by MCF7/P and MCF7/TAM cells in the presence or absence of LAP and BB for 1^st and 2^nd generations. The columns represent the means of three experiments; bars, SE. * & #, P<0.05 for MCF/TAM cells treated with vehicle vs cells treated with tamoxifen and LAP or BB, respectively.