Figure 7

A. Exogenous supplementation with oleuropein aglycone down-regulates HER2 expression and synergistically enhances trastuzumab-induced depletion of HER2 in trastuzumab-resistant SKBR3/Tzb100 cells. Overnight serum-starved SKBR3/Tzb100 cells were cultured in DMEM-0.1% FBS supplemented with increasing concentrations of oleuropein aglycone in the absence or presence of trastuzumab for 72 h. The Oncogene Science HER2 microtiter ELISA was used according to the manufacturer's instructions to compare HER2 concentrations in cell pellets. B. Oleuropein aglycone treatment does not affect EGFR (HER1) expression in trastuzumab-sensitive SKBR3 parental cell line (SKBR3/Wild Type) and in its derivative trastuzumab-resistant SKBR3/Tzb100 pool. Overnight serum-starved SKBR3/Tzb100 cells were cultured in DMEM-0.1% FBS supplemented with increasing concentrations of oleuropein aglycone in the absence or presence of trastuzumab for 72 h. The Oncogene Science HER1 (EGFR) microtiter ELISA was used according to the manufacturer's instructions to compare HER1 concentrations in cell pellets. Results in Aand Bare means (columns) and 95% confidence intervals (bars) of three independent experiments made in triplicate. Statistically significant differences (one-factor ANOVA analysis) between experimental conditions and unsupplemented control cells are shown by asterisks (* P < .01, ** P < .001). All statistical tests were two-sided.