Diphtheria toxin-epidermal growth factor fusion protein and Pseudomonas exotoxin-interleukin 13 fusion protein exert synergistic toxicity against human glioblastoma multiforme cells.
The cytotoxicity of combinations of a diphtheria toxin-human epidermal growth factor fusion protein (DAB(389)EGF) and a Pseudomonas exotoxin-human interleukin 13 fusion protein (IL13PE38QQR) was tested against 14 human glioma cell lines. After cells were cultured for 48 h with various concentrations of the fusion proteins, the percentage reductions in thymidine incorporation were determined. Seven of fourteen cell lines were highly sensitive to DAB(389)EGF alone, and six cell lines were highly sensitive to IL13PE38QQR alone with IC(90)'s < 100 pM. When combined, synergistic cell killing was observed for seven of the cell lines based upon concave isobolograms and combination indices (CI's) of 0.2 to 0.7. Supraadditive cytotoxicity was confirmed by measurements of induction of apoptosis. Receptor expression was assessed by flow cytometry and confocal microscopy. Marked heterogeneity of expression of EGFR and IL13Ralpha2 was seen on all the glioma cell lines. This heterogeneity may contribute to incomplete cell killing with the individual fusion proteins and synergistic cell kill with the combination. These results suggest that both fusion proteins may yield antitumor effects in patients with recurrent gliomas and that combination fusion protein intracranial therapy of malignant gliomas may yield an improved therapeutic index.
Liu
Tie Fu
TF
Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Willingham
Mark C
MC
Tatter
Stephen B
SB
Cohen
Kimberley A
KA
Lowe
A Corinne
AC
Thorburn
Andrew
A
Frankel
Arthur E
AE
D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D004167:Diphtheria Toxin / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D004815:Epidermal Growth Factor / Q000235:genetics / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D005098:Exotoxins / Q000235:genetics / Q000494:pharmacology*; D005434:Flow Cytometry; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D018793:Interleukin-13 / Q000235:genetics / Q000494:pharmacology*; D018613:Microscopy, Confocal; D018123:Receptors, Interleukin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000494:pharmacology*; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000494:pharmacology*
D000970:Antineoplastic Agents; D004167:Diphtheria Toxin; D005098:Exotoxins; D018793:Interleukin-13; D018123:Receptors, Interleukin; D011993:Recombinant Fusion Proteins; D016211:Transforming Growth Factor alpha; C062005:transforming growth factor type alpha-Pseudomonas exotoxin A; D004815:Epidermal Growth Factor; D066246:ErbB Receptors