Figure 3

HER2 signal after BerEP4 selection in normal donors, patient samples and SKBR3 spiked normal blood samples. Blood samples from 36 metastatic breast cancer patients, 23 normal donors and three normal donor samples spiked with 10 SKBR3 human breast cancer cells were subjected to BerEP4 immunomagnetic enrichment for epithelial cells. After RNA extraction from the positively selected cellular fraction, HER2 and B2M expression were quantitated by real time qRT-PCR. The standard curve was obtained by serial dilution of DNA from a HER2 positive breast cancer cell line (BT474). HER2 relative expression per sample was calculated by obtaining the HER2 value/B2M value ratio for each sample and then normalizing against the HER2/B2M ratio of Normal Control Sample N4, as it represented the median value for HER2 in normal samples. Error bars represent the standard deviation of triplicate reactions. Normal controls are depicted by cross hatched mark. Samples from breast cancer patients are depicted in grey bars (HER2 negative tumors) and black bars (HER2 positive tumors).