Figure 1.

ERBB2 and EGFR expression pattern in BCSCs and during differentiation. (a) Immunohistochemistry of three different paraffin-embedded primary tumor tissues (left), CSCs lines derived from tumors (centre) and SDACs (right) stained with anti-HER2 antibodies (pink-brown) (Scale bar: 20 μM). ERBB2 is expressed in primary tumors but not in CSCs lines and starts to be re-expressed under differentiating condition (SDAC). (b) Western blot analysis of BCSC lines (BCSC#1, BCSC#2 and BCSC#3) and stem cells under differentiating condition (SDAC) for 3.5 and 7 days using antibodies against ERBB2, EGFR and Actin as a loading control. The corresponding molecular weights are indicated on the left (KDa). ERBB2 and EGFR expression increases during differentiating condition. (c) qRT-PCR of ERBB2 and EGFR levels of BCSC lines (BCSC#1, BCSC#2 and BCSC#3) and SDAC of the same lines differentiated for 3.5 and 7 days. Data represent mean±S.D. of three different experiments analyzed in triplicate. Statistical significance was analyzed using Student's T test (*P<0.05). (d) BCSCs are resistant to Lapatinib treatment. Cell proliferation assay of BCSCs and SDAC untreated (ctr) or treated with 0.5 μM of Lapatinib at the indicated time points (days). SDAC were differentiated for 3.5 days and then plated for growth curve analysis. BCSCs express low receptors levels and are more resistant to treatment than SDAC. Data represent mean±S.D. of three different experiments and P values are shown in the graphs