Table 1

Comparison of protein expression levels of EGFR and ErbB2 and ZD1839- and C225-induced growth inhibition and clonogenic survival

Cell lineRelative EGFR expressionaRelative ErbB2 expressionaGrowth inhibitionClonogenic survival
IC50b% (SD)c% (SD)c% (SD)d% (SD)d
A431154.00.177 (±3)62 (±8)55 (±7)60 (±15)
A5492.03.02.446 (±7)49 (±11)97 (±4)97 (±15)
H17034.16.97.629 (±3)35 (±11)n.d.en.d.
SW15731.84.51520 (±8)19 (±10)95 (±10)108 (±14)
H4601.53.12425 (±5)29 (±5)105 (±5)103 (±8)
  • a Protein expression levels were analyzed by flow cytometry (see “Materials and Methods”).

  • b Drug concentrations (μm) responsible for 50% growth inhibition in MTT assay at 72 h, calculated with data of at least three independent experiments.

  • c Growth inhibition induced by ZD1839 (1 μm) or C225 (5 μg/ml) represented as a percentage of untreated cells, analyzed by MTT assay at 72 h. Mean and SD of at least three independent experiments are shown.

  • d Colony-forming units are expressed as a percentage of the respective untreated control. Mean and SD of one representative experiment done in triplicate are shown.

  • e n.d., not determined.