Subject(s)
Cell Transformation, Neoplastic , Gene Expression Regulation , Neuroblastoma/genetics , Oncogenes , Tumor Cells, Cultured/metabolism , Azacitidine/pharmacology , Cell Line , Cell Transformation, Neoplastic/drug effects , Gene Amplification , Gene Expression Regulation/drug effects , Humans , Methylation , Neuroblastoma/metabolism , Oncogenes/drug effects , Phenotype , Time Factors , Tumor Cells, Cultured/drug effectsABSTRACT
We have analyzed a 3.8 kb Eco RI fragment of genomic DNA obtained from the amplified N-myc gene of human neuroblastoma cell line BE(2)-C. This fragment contains an exon with an open reading frame encoding approximately 170 amino acids of the carboxy-terminal end of the putative N-myc protein. Comparison of the inferred amino acid sequence of this peptide with that of the 3' domain of the human c-myc protein shows that locally conserved but dispersed regions of homology exist throughout the lengths of these peptides, while hydropathy plots indicate that the physical properties implied by their primary sequences are strikingly similar. Based upon these and other considerations, it is suggested that the 3' domains of c-myc and N-myc may potentially share related functions.
Subject(s)
Oncogenes , Amino Acid Sequence , Base Sequence , Cell Line , Computers , DNA Restriction Enzymes/metabolism , Deoxyribonuclease EcoRI , Humans , Neoplasm Proteins/genetics , Neuroblastoma/geneticsSubject(s)
DNA, Neoplasm/genetics , Gene Amplification , Neuroblastoma/genetics , Base Sequence , Cell Line , Humans , OncogenesABSTRACT
Screening of a partial cDNA library prepared from the human neuroblastoma cell line BE(2)-C with genomic DNA probes containing sequences representative of the amplified domain of that cell line allowed us to identify cloned transcripts from an active gene within the domain. The gene BE(2)-C-59 is amplified ca. 150-fold and encodes a 3.0- and a 1.5-kilobase RNA transcript, both of which are overproduced in BE(2)-C cells. A survey of a large variety of human tumor cell types indicated that this gene is amplified to varying degrees in all neuroblastoma cell lines and a retinoblastoma cell line that exhibit obvious cytological manifestations of DNA sequence amplification, i.e., homogeneously staining regions and double-minute chromosomes. The BE(2)-C-59 gene is not amplified, however, in other nonrelated tumor types, even those containing amplified DNA. Although the functional significance of this specific gene amplification in neuroblastoma cells remains unknown, an indication that it may relate to the malignant phenotype of these cells follows from the remainder of our data which show that the amplified BE(2)-C-59 gene shares partial homology with both the second and third exons, but not the first exon, of the human c-myc oncogene.
