Fig. 1. HPIMBD significantly inhibits the proliferation of breast cancer cell lines and shows a dose- and time-dependent cytotoxicity.

a) Non-neoplastic breast epithelial cell line MCF-10A and breast cancer cell lines MCF-7, T47D, MDA-MB-231, vector-transfected and ERβ1-transfected MDA-MB-231 were treated with vehicle (DMSO), 50 μM Res or HPIMBD for 72 hours and MTT assays were performed. Percentage proliferation was determined by dividing the absorbance in the HPIMBD- or Res-treated cells by that in vehicle-treated cells X 100. Each experiment was performed in quadruplicate and data are expressed as percentage proliferation + SEM relative to respective vehicle-treated controls.

b) LDH release assays were performed on non-neoplastic breast epithelial and breast cancer cell lines as described above. Percentage increase in LDH release was determined by dividing the difference of absorbances between HPIMBD- or Res-treated and vehicle-treated cells to the difference of absorbances between total intracellular LDH and vehicle-treated cells X 100. Each experiment was performed in triplicate and data are expressed as percentage LDH release + SEM relative to respective vehicle-treated controls (taken as 0%).

c–h) Non-tumorigenic breast epithelial cell line and breast cancer cell lines were treated with vehicle (DMSO) or graded doses of HPIMBD for up to 72 hours and LDH release assays were performed. Percentage increase in LDH release was determined as described above.

i) Non-neoplastic breast epithelial cell line and breast cancer cell lines were treated with vehicle (DMSO), 50 μM Res or HPIMBD for 48 hours and BrdU incorporation assays were performed. Each experiment was performed in triplicate and the data are expressed as percentage BrdU incorporation + SEM.

(*) indicates a P value <0.05 compared to controls.