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Table 1 Mean half-maximal inhibitory concentrations for lapatinib inhibition of HER2 and signaling proteins in PIK3CA mutant cells a

From: Direct inhibition of PI3K in combination with dual HER2 inhibitors is required for optimal antitumor activity in HER2+ breast cancer cells

  HER2 Akt Increase over WT S6 Increase over WT
BT474 0.0411 0.0300   0.0347  
BT474 LR 0.0204 0.3925 13.1 0.7863 22.7
BT474 wt 0.0798 0.0387   0.0506  
BT474 E545K 0.0852 0.1098 2.8 0.1251 2.5
BT474 H1047R 0.0978 0.1336 3.4 0.1829 3.6
SKBR3 0.0254 0.0077   0.0106  
SKBR3 wt 0.0297 0.0293   0.0593  
SKBR3 E545K 0.0211 0.0936 3.2 0.1563 2.6
SKBR3 H1047R 0.0241 0.0770 2.6 0.2028 3.4
MDA361 0.0160 0.0092 0.5 0.0354 1.6
HCC1954 0.0681 0.2527 13.4 0.1678 7.4
SUM190 0.0465 0.0464 2.5 0.1461 6.5
UACC893 0.0444 0.2920 15.5 4.0040 177.0
  1. aWT, Wild type. Half-maximal inhibitory concentration (IC50) values for inhibition of HER2, Akt and S6 phosphorylation by lapatinib treatment were determined by enzyme-linked immunosorbent assay (dose–response curves are shown in Additional file 6: Figure S2, Additional file 7: Figure S3 and Additional file 8: Figure S4). Mean IC50 values derived from at least three separate experiments are shown. For phosphoinositide 3-kinase signaling proteins Akt and S6, IC50 values from cells with PIK3CA mutations were compared to average values for cells without hotspot mutations (BT474 and SKBR3).