Expression of cytoplasmic-domain substituted epidermal growth factor receptor inhibits tumorigenicity of EGFR-overexpressed human glioblastoma multiforme.
The accumulated results of recent clinical studies have indicated that aberrant epidermal growth factor receptor (EGFR) activation due to gene amplification and/or rearrangement contributes to increased malignancy and poor prognosis in many human cancers, especially in human glioblastoma multiforme (GBM). The elevated EGFR signaling in GBM has been correlated with shorter interval to relapse and lower survival rates, even in patients treated with surgery, radiation therapy, and/or chemotherapy. Therefore, the blockade of EGFR signaling in GBM may provide an ideal alternative therapeutic strategy. In this study, two EGFR-overexpressing human GBM cell lines (i.e., DBTRG and GBM 8901) were used as a model system. We demonstrated that expression of a human EGFR (EGFRt-EGFP) chimera protein in which the cytoplasmic domain is substituted by EGFP significantly reduced the EGF-induced endogenous EGFR autophosphorylation, EGF-induced downstream extra-cellular signal-regulated kinase (ERK) and Akt signaling, and the proportion of internalized receptors in EGF stimulated cells. Furthermore, these cells' anchorage-independent growth in vitro was decreased and their tumorigenicity in vivo abrogated or strongly suppressed. Our data suggest that EGFRt-EGFP abrogates tumor growth by disrupting receptor activation via competing for EGF-like ligands, forming non-activated heterodimers with endogenous EGFR, and inhibiting the EGFR endosomal signaling by substantially diminishing receptor internalization. This treatment modality (termed 'dominant-negative EGFR therapy') and its efficacy for gliomas or other tumors are under scrutiny.
Liu
Ko-Jiunn
KJ
Division of Cancer Research, NHRI, Taipei 100, Taiwan, ROC.
Chen
Chun-Ting
CT
Hu
Wensi S
WS
Hung
Yi-Mei
YM
Hsu
Chiung-Yueh
CY
Chuang
Bin-Fay
BF
Juang
Shin-Hun
SH
D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D045744:Cell Line, Tumor; D016543:Central Nervous System Neoplasms / Q000378:metabolism* / Q000628:therapy; D003593:Cytoplasm / Q000378:metabolism*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D005799:Genes, Dominant; D005822:Genetic Vectors; D005909:Glioblastoma / Q000378:metabolism* / Q000628:therapy; D049452:Green Fluorescent Proteins; D006801:Humans; D008024:Ligands; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D012685:Sepharose / Q000737:chemistry; D015398:Signal Transduction; D013997:Time Factors
D008024:Ligands; D008164:Luminescent Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D012685:Sepharose; D066246:ErbB Receptors; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases