Figure 7. Combined inhibition of EGFRvIII and PDGFRβ in EGFRvIII-expressing GBM cells.
A. and B. U87MG/EGFRvIII cells (in A, 3.6 × 103 cells/well on 96-well plates; in B, 105 cells/3.5-cm plate) were mock-treated or treated for 24 hours with 5 μmol/l gefitinib or 200 nmol/l CL4. Then the incubation was prolonged for further 72 hours with the above treatments alone or in combination with 200 nmol/l Gint4.T, by renewing the treatment each 24 hours. As a negative control, cells were treated with 400 nmol/l CL4Sc for 96 hours. In A, cell viability was analyzed and expressed as percent of viable treated cells with respect to mock-treated cells. In B, cells were counted through the Bürker chamber and cell number with respect to mock-treated cells, was reported. C. Lysates from VS-GB/ctr or VS-GB/EGFRvIII cells were immunoblotted with anti-EGFR and anti-PDGFRβ antibodies. Equal loading was confirmed by immunoblot with anti-vinculin antibody. Values below the blots indicate signal levels relative to VS-GB/ctr, arbitrarily set to 1 (labeled with asterisk). D. and E. VS-GB/EGFRvIII cells were treated as in A, B and cell viability D. and cell number E. were reported as for U87MG/EGFRvIII cells. Bars depict means ± SD of three independent experiments. **P < 0.01; *P < 0.05 relative to controls (mock-treated and CL4Sc). ### P < 0.001; ## P < 0.01.