Identification and analysis of the ret proto-oncogene promoter region in neuroblastoma cell lines and medullary thyroid carcinomas from MEN2A patients.
The human ret proto-oncogene (proto-ret), encoding a receptor tyrosine kinase, is highly expressed in neuroblastomas, medullary thyroid carcinomas (MTCs) and pheochromocytomas, which are all tumors of cells originating from the neural crest. In studies on the transcription mechanism of proto-ret, we identified the transcription start site and the promoter region by chloramphenicol acetyl transferase (CAT) assay. A sequence upstream from the transcription start site (-167 to +98 bp) showed definite promoter activity in both proto-ret mRNA-positive neuroblastoma NB39-nu cells and proto-ret mRNA-negative HeLa cells. The promoter sequence had a high GC content and contained four tandemly repeated GC boxes without a TATA box. Putative binding sequences for SP-1, AP-2 and epidermal growth factor receptor-specific transcription factor (ETF) and also the transcription-suppressing factor, GC factor (GCF), were found in the repeated GC box region. Southern blot analysis of DNAs of neuroblastoma cell lines and primary MTCs showed that the high proto-ret expression in these tumors is not caused by gross genetic changes in the promoter region, suggesting the possible involvement of a region(s) other than the sequence from -167 to +98 bp or a minor genetic change(s) in the promoter region.
Itoh
F
F
Carcinogenesis Division, National Cancer Center Research Institute, Tokyo, Japan.
Ishizaka
Y
Y
Tahira
T
T
Yamamoto
M
M
Miya
A
A
Imai
K
K
Yachi
A
A
Takai
S
S
Sugimura
T
T
Nagao
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004273:DNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D029721:Drosophila Proteins; D006801:Humans; D008214:Lymphocytes / Q000502:physiology; D008969:Molecular Sequence Data; D009377:Multiple Endocrine Neoplasia / Q000235:genetics*; D009447:Neuroblastoma / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051096:Proto-Oncogene Proteins c-ret; D011519:Proto-Oncogenes; D020794:Receptor Protein-Tyrosine Kinases; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping; D013964:Thyroid Neoplasms / Q000235:genetics*
D004273:DNA, Neoplasm; D029721:Drosophila Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase; D011505:Protein-Tyrosine Kinases; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila