Tyrosine kinase activity may be necessary but is not sufficient for c-erbB1-mediated tissue-specific tumorigenicity.
Expression of mutant avian c-erbB1 genes results in tissue-specific transformation in chickens. Site-directed mutagenesis was used to generate kinase-defective mutants of several tissue-specific v-erbB transforming mutants by replacement of the ATP-binding lysine residue in the kinase domain with an arginine residue. These kinase-defective v-erbB mutants were analyzed for their in vitro and in vivo transforming potentials. Specifically, kinase-defective mutants of erythroleukemogenic, hemangioma-inducing, and sarcomagenic v-erbB genes were assessed for their oncogenic potential. In vitro transformation potential was assessed by soft-agar colony formation in primary cultures of chick embryo fibroblasts (CEF). In vivo transformation potential was determined by infection of 1-day-old line 0 chicks with concentrated recombinant retrovirus and then monitoring of birds for tumor formation. These transformation assays demonstrate that kinase activity is absolutely essential for transformation by tissue-specific transforming mutants of the avian c-erbB1 gene. Since all of the tissue-specific v-erbB mutants characterized to date exhibit tyrosine kinase activity in vitro but do not transform all tissues in which they are expressed, we conclude that v-erbB-associated tyrosine kinase activity may be necessary but is not sufficient to induce tumor formation.
Connolly
D C
DC
Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905.
Toutenhoofd
S L
SL
Maihle
N J
NJ
D001355:Alpharetrovirus / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D003062:Codon / Q000235:genetics; D017931:DNA Primers; D066246:ErbB Receptors / Q000096:biosynthesis* / Q000302:isolation & purification; D005347:Fibroblasts; D017353:Gene Deletion; D008969:Molecular Sequence Data; D016296:Mutagenesis; D018739:Oncogene Proteins v-erbB; D009857:Oncogenes; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D011519:Proto-Oncogenes; D015183:Restriction Mapping; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis* / Q000302:isolation & purification
D003062:Codon; D017931:DNA Primers; D018739:Oncogene Proteins v-erbB; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases