FIGURE 1

Herceptin treatment induced growth suppression in breast cancer cell lines. Breast cancer cell lines obtained from ATCC (Manassas, VA, USA) were grown under recommended culture conditions. Exponentially growing cells were harvested and plated on 96-well plates at a defined density, ranging from 2.5 10⁴–6.5 10⁴ cells/ml depending on cell line. After 48 h, Herceptin (Genentech, Inc., South San Francisco, CA, USA) was added to the cell cultures at concentrations of 1, 10, 100, and 500 g/ml. Fresh medium lacking Herceptin was added to control wells of each cell line. After 72 h incubation, the medium was replaced with a fresh drug-free medium and the cells were allowed to recover for additional 18 h. The suppression of cell growth was determined using the alamarBlue Assay (Alamar Biosciences, Sacramento, CA, USA). AlamarBlue was added to the wells in an amount equal to 10% of the total culture medium volume. AlamarBlue was incubated for 4–10 h, and absorbance at 540 and 620 nm wavelengths was measured with a spectrophotometer. The growth suppression of Herceptin-treated vs untreated control cells were calculated according to the manufacturer's instructions (Alamar Biosciences, Sacramento, CA, USA). Mean+1 s.d. of triplicate experiments are shown