title: cph, a novel oncogene which cooperates with H-ras in the transformation of NIH3T3 fibroblasts.
abstract: We have performed the molecular cloning of the non-ras transforming sequences previously detected in neoplastic Syrian hamster embryo fibroblasts initiated in vitro with 3-methylcholanthrene (MCA) (Notario et al., 1990). These sequences were isolated using cosmid-rescue techniques from a third-cycle NIH3T3 transformant obtained by sequential transfections of genomic DNA from MCA-initiated hamster fetal cells. Rescued (C-5) clones encompassed about 42.5 kbp of Syrian hamster genomic DNA containing hamster-specific repetitive elements (HRS). An internal 19 kbp BamHI fragment (B-1) was the only C-5 fragment which recognized specific transcripts in poly(A)+ RNA from hamster embryo cells. The same mRNA species were present in both normal and MCA-initiated neoplastic cells: a major transcript of about 2.5 kb, and other less abundant ones, ranging from approximately 2.0 kb to 5.0 kb. These mRNA species were detected consistently by each of several B-1 DNA subfragments located at positions spanning almost the entire B-1 length. The nucleotide sequence of some transcript-positive (S5P2 and S6) genomic B-1 fragments was determined. No significant homology exists between the nucleotide sequences of these B-1 subfragments and established DNA databases. Therefore, the C-5 cosmid clone contains novel genomic sequences. Transfection of C-5 DNA into mouse NIH3T3 cells resulted in the appearance of transformed foci (about five foci per microgram of DNA) within 25 days post-transfection, thus demonstrating the transforming activity of the C-5 clone, which was consequently renamed as the cph oncogene. Co-transfection of the cph oncogene with the human H-ras oncogene (T24), demonstrated a synergistic action between the two oncogenes in the transformation of murine fibroblasts.
authors.affiliation: Department of Radiation Medicine, Georgetown University Medical Center, Washington, DC 20007.
authors.forename: J A
authors.initials: JA
authors.lastname: Velasco
authors.forename: R
authors.initials: R
authors.lastname: Castro
authors.forename: M A
authors.initials: MA
authors.lastname: Avila
authors.forename: J
authors.initials: J
authors.lastname: Laborda
authors.forename: J A
authors.initials: JA
authors.lastname: DiPaolo
authors.forename: J
authors.initials: J
authors.lastname: Cansado
authors.forename: V
authors.initials: V
authors.lastname: Notario
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D003001:Cloning, Molecular; D006224:Cricetinae; D011905:Genes, ras; D008647:Mesocricetus; D051379:Mice; D009857:Oncogenes