Specific short transmembrane sequences can inhibit transformation by the mutant neu growth factor receptor in vitro and in vivo.
The neu oncogene is activated by a point mutation within its transmembrane domain that results in the substitution of glutamic acid for valine at position 664, and is associated with constitutive activation of the tyrosine kinase. It has been proposed that the mutation allows for stabilization of homodimers of the receptor that are necessary for transduction of the mitogenic signal. To investigate the role of the alpha-helical transmembrane sequence in the function of neu, we constructed an expression vector to produce a variety of short transmembrane neu proteins, lacking ligand binding or intracellular kinase domains. Such sequences should interact with full-length receptors and prevent receptor dimerization and thus act as specific inhibitors of function. These small proteins all included a pentapeptide from position 661-665, which has been proposed to be necessary for packing. We show that the short transmembrane molecules are expressed at the cell surface and can retard the growth of neu-transformed cells in monolayers, as colonies in soft agar and as tumours in animals. As predicted by molecular modelling, the magnitude of inhibition depended on the nature of the packing surface, suggesting that the neu transmembrane domain is directly involved in neu protein dimerization.
Lofts
F J
FJ
Molecular Oncology Laboratory, Hammersmith Hospital, London, UK.
Hurst
H C
HC
Sternberg
M J
MJ
Gullick
W J
WJ
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D002455:Cell Division; D002462:Cell Membrane / Q000737:chemistry; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D015536:Down-Regulation; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology*; D009368:Neoplasm Transplantation; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000737:chemistry* / Q000502:physiology; D018719:Erb-b2 Receptor Tyrosine Kinases; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D011518:Proto-Oncogene Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases